FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)

FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)

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Zitieren:FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine) // Геофизический журнал. — 2017. — Т. 39, № 4. — С. 77-124. — англ.

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spelling irk-123456789-1276632017-12-25T03:03:56Z FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine) 2017 Article FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine) // Геофизический журнал. — 2017. — Т. 39, № 4. — С. 77-124. — англ. 0203-3100 http://dspace.nbuv.gov.ua/handle/123456789/127663 ru Геофизический журнал Інститут геофізики ім. С.I. Субботіна НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
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format Article
title FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)
spellingShingle FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)
Геофизический журнал
title_short FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)
title_full FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)
title_fullStr FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)
title_full_unstemmed FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine)
title_sort final workshop of international research group project "south caucasus geosciences" (october 25-27, 2017, kyiv, ukraine)
publisher Інститут геофізики ім. С.I. Субботіна НАН України
publishDate 2017
url http://dspace.nbuv.gov.ua/handle/123456789/127663
citation_txt FINAL WORKSHOP of International Research Group Project "SOUTH CAUCASUS GEOSCIENCES" (October 25-27, 2017, Kyiv, Ukraine) // Геофизический журнал. — 2017. — Т. 39, № 4. — С. 77-124. — англ.
series Геофизический журнал
first_indexed 2025-07-09T07:28:33Z
last_indexed 2025-07-09T07:28:33Z
_version_ 1837153508328996864
fulltext International Research Group Project SOUTH CAUCASUS GEOSCIENCES FINAL WORKSHOP O ctober 25-27, 2017 Kiev, U kraine The W orkshop is organized by: CNRS, U niversité Côte d 'A zur, UM R G eoazur UNS, O bservatoire de la Côte d 'A zur, IRD, Sophia A ntipo lis France S.I. S ubbo tin Institu te of G eophysics, N ational Academ y of Sciences of U kraine, Kiev U kraine INTERNATIONAL RESEARCH GROUP PROJECT Tethyan evolution and continental collision in SW Caucasus (Georgia and adjacent areas) © S. Adam ia, V. A lania, A . G ventsadze, O. Enukidze, N . Sadradze, N . Tsereteli, G. Zakariadze, 2017 Tbilisi State University, M. Nodia Institute of Geophysics, Tbilisi, Georgia Georgia, the westernmost part of the southern Caucasus located at the junction of European and Asiatic branches of the Al- pine-Himalayan orogenic belt represents an area where the Tethys Ocean was completely closed only in the late Cenozoic as a result of prolonged convergence between the Eurasian and Africa-Arabian plates. During the Neoproterozoic—early Ceno­ zoic, the territory of Georgia and the adja­ cent area of the Black Sea-Caspian Sea region were parts of the Tethys Ocean and its north­ ern and southern margins. The Prototethys- Paleotethys-Tethys was not a single continu­ ous oceanic plate, but rather developed in branches separating continental terranes of different sizes, which rifted and drifted away from the Gondwana margin and eventually collided with Laurasia. Prior to the final col­ lision in the late Cenozoic, the region hosted systems of island arc, intra-arc, and back-arc basins located between the East European (Baltica) continent and Gondwana. Integra­ tive geological and paleogeographical stud­ ies show a collage of several tectonic units (terranes) in Georgia and adjoining areas that have distinctive geological histories with Tethyan, Eurasian, or Gondwanian affinities. These include the Scythian platform, the Cav- casioni (Great Caucasus), the Transcaucasus- Pontides, and the Lesser Cavcasioni (Cauca­ sus)—Alborz—West Iran regions. Their posi­ tion between the Africa-Arabian and Eurasi- atic continents provides a reason for grouping them into the Northern Tethyan (Eurasian) and Southern Tethyan (Gondwanian) do­ mains. The Scythian platform, Caucasioni, and Transcaucasus-Pontian belts are of North Tethyan origin while Anatolia, Taurus, Iran, and the southern Lesser Caucasus belong to the South Tethys. The Arabia-Nubian Shield, at the end of the Proterozoic, experienced basement con­ solidation related to the final stages of the Pan-African cycle of tectogenesis. In contrast to the southern Lesser Caucasus (Daralagoz), the Transcaucasus did not undergo this pro­ cess because it broke away from the Arabia- Nubia Shield and, during Cambrian—Devo­ nian, drifted deep into the Prototethys toward the northern (Baltica) continent. During the early—middle Paleozoic in the wake of northward-migrating Gondwanian fragments, the Paleotethyan basin formed, and, in the Ordovician, along its border with the Transcaucasus, subduction of oceanic crust occurred, accompanied by suprasu- bduction volcanic eruptions. Northward mi­ gration of the Transcaucasus throughout the Paleozoic caused narrowing of the Protote­ thys and its transformation into an oceanic back-arc (Dizi) basin. Fragments of paleoce- anic crust are found along the southern bor­ der of the Transcaucasus, within accretionary complexes of the Lesser Caucasus ophiolite suture, and in the Pontides, also in Iranian Garadagh. During the late Paleozoic—early Mesozoic, the oceanic basin separating the Africa-Arabian continent from the Taurus- Anatolian-Iranian platformal domain gradu­ ally extended. During this phase, only the Central Iranian terrain separated from Gond­ wana, drifted northward, and collided with the Eurasian continent in the Late Triassic. 78 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES The Taurus-Anatolian terrane separated from Gondwana later, in the Early-Middle Jurassic. During the Mesozoic—Cenozoic, Daralagoz represented the northwestern most margin of the Central Iranian platform and was sepa­ rated from the North Anatolian platform by an oceanic or back-arc basin (Khoy basin), which within the modem structure is represented by Mesozoic — Cenozoic ophiolites of Urumieh- Khoy (Iran) and Van (Turkey). The Paleozoic-Eocene evolution of the North Tethyan domain was m arked by major magmatic events corresponding to the Pacif­ ic-type and M editerranean stages of Tethyan development. The precollisional magmatic assemblages reflect a variety of paleotectonic environments. They are indicative of a west Pacific-type oceanic setting in which a ma­ ture, Andean-type continental arc developed. There were several episodes of oceanic litho­ spheric obduction onto the continental ter- ranes of the region: the middle-late Paleozoic, during which basite-ultrabasite complexes were thrust over the island-arc system of the Transcaucasus and the Main Range zone of Caucasioni; pre-Late Triassic obduction in the Lesser Caucasus; and pre-Late Jurassic obduction during which ultrabasic rocks were thrust over the continental unit of the Artvin- Bolnisi Block of the Somkhet-Garabagh zone. The metabasites apparently represent Paleo- tethyan fragments. During the Oligocene, marine Tethyan ba­ sins were replaced by euxinic basins, which are considered to represent the beginning of syncollisional development between Ara­ bian and Eurasian plates in the region. On­ going collision during M iocene—Quater­ nary caused inversion of topography such that fold-and-thrust mountain belts of the Cavcasioni and Lesser Cavcasioni, and the intermontane foreland basins in between were formed. In the late Miocene, coeval with molasse deposition in the foreland basins, subaerial volcanic eruptions occurred, char­ acterized by intensively fractionated magma of suprasubduction-type calc-alkaline series from basalts to rhyolites. In addition to volcanism, earthquakes indi­ cate active tectonics in Georgia. Some of the 36°E 42°E 48°E 54°E 42°N 36°N ]Q mm/vr 95% confidence Fig. 1. Map showing global positioning system (GPS) velocities with respect to Eurasia and 95 % confidence ellipses for the eastern Black Sea—Caucasus—Caspian region [Vemant et al., 2013]. reo(pU3UHecxiiu xcypiiaA № 4, T. 39, 2017 79 INTERNATIONAL RESEARCH GROUP PROJECT major earthquakes have proven to be devas­ tating; i.e., the Racha earthquake of 29 April 1991, with Ms=6.9, was the strongest ever re­ corded in Georgia. The fault plane solution data for 130 earthquakes show that the terri­ tory of Georgia is currently under latitudinal compression, longitudinal extension, and an overall crustal thickening. A complex network of faults divides the region into a number of separate blocks. Three principal directions of active faults compatible with the dominant, near N-S compressional stress produced by northward displacement of the Arabian plate can be distinguished: one longitudinal, trend­ ing WNW-ESE or W-E, and two transversal, trending NE-SW and NW-SE. The first group (WNW-ESE), the so-called «Caucasian» strike, is composed of compressional struc­ tures, including reverse faults, thrusts, thrust slices, and strongly deformed fault-propa­ gation folds. The transversal faults are also mainly compressional structures, but they contain considerable strike-slip components as well. The tensional nature of submeridional faults is associated with intensive Neogene- Quaternary volcanism in the Transcaucasus. The NE-SW left-lateral strike-slip faults are the main seismoactive structures in the west­ ern Transcaucasus, while right-lateral strike- slip faults are developed in the southeastern Transcaucasus. Considerable shortening and References SmitJ. H. V., Cloetingh S. A. P. L., Burov E., Tesauro M., Sokoutis D., Kaban M., 2013. Interference of litho­ spheric folding in western Central Asia by simulta­ neous Indian and Arabian plate indentation. Tecto- nophysics 602(Spec. is. Topo-Europe III), 176—194. https://doi.Org/10.1016/j.tecto.2012.10.032. VemantP., KingR., ReilingerR., Floyd M„ McCluskyS., Hahubia C., Sokhadze G., Elashvili M„ Kadirov F., deformation of the crust and lithosphere of the region have taken place via compres­ sional structures, as well as lateral tectonic escape. The geometry of the topography and tectonic features is largely determined by the wedge-shaped rigid Arabian block (indentor) and by the configuration of the oceanic-sub- oceanic lithosphere (buttresse) of the eastern Black Sea and south Caspian Sea, all of which cause bending of the main morphological and tectonic structures of the region around the strong lithosphere (Fig. 1). Large-scale intraplate deformation of the lithosphere of the region as a result of the in­ dentation of Arabian and Indian plates result­ ed in Late Cenozoic shortening and uplift of the mountain belts of the region, subsidence acceleration of the Black Sea—South Caspian crust, formation of submeridional, transversal m egastructure of the Caspian Sea that evi­ dence for interference of lithospheric folding patterns induced by the Arabian and Indian collision with Eurasia [Smit et al., 2013]. Acknowledgements. This work was sup­ ported by Shota Rustaveli National Science Foundation (SRNSF), projects № 04-45 (GDRI — International Research Group: South Cau­ casus GeoScience (Georgia — Eastern Black Sea)) and № 217408 (Interactive Geological Map of Georgia, scale 1:200 000). KarakhanianA.,AvagyanA., ErgintavS., DjamourY., Doerflinger E., RitzJ.-F., 2013. GPS constraints on continental deformation in the Black Sea, Caucasus and Caspian region: Implications on geodynamics and seismic hazard. Darius Programme (24—25June, 2013), Eastern Black Sea and Caucasus, Abstracts Volume: Tbilisi, Georgia, I. Javakhishvili Tbilisi State University, P. 74—75. 80 Teo(pu3 UHecKuü xypnaA Ne 4, T. 39, 2017 https://doi.Org/10.1016/j.tecto.2012.10.032 SOUTH CAUCASUS GEOSCIENCES Structural architecture of the eastern Achara-Trialeti fold and thrust belt, Georgia: Implications for kinematic evolution © V. A lania1, M . Sosson2, O. E nukidze1, N . A sa tia n f, T. Beridze4, Z. Candaux2, A. Chabukiani1, A. Giorgadze3, A . G ventsadze1, N . K vavadze1, G. K vintradze3, N . Tsereteli1, 2017 1Tbilisi State University, M. Nodia Institute of Geophysics, Tbilisi, Georgia 2Université Côte d'Azur, UMR Géoazur, CNRS, Observatoire de la Côte d ’Azur, IRD, Sophia Antipolis, France 3Tbilisi State University, Faculty of Exact and Natural Sciences, Tbilisi, Georgia 4Tbilisi State University, A. Janelidze Institute of Geology, Tbilisi, Georgia We introduce a tectonic model of the east­ ern Achara-Trialeti fold and thrust belt (AT- FTB) based on the recent field data, inter­ preted seismic reflection profiles and regional balanced cross section from northern part of Lesser Caucasus orogene. Like other collision- induced Alpine-type fold-thrust belts (e.g. [Naylor, Sinclair, 2008]), the Lesser Caucasus is a typical doubly-vergent orogenic wedge represented by pro and retro wedges and ATFTB is a constituent part of retro wedge [Alania et al., 2017]. The seismic interpretation presented here is further constrained by surface geology and subsurface geology revealed by several well penetrations. Fault-related folding theories were used to constrain the seismic interpre­ tation and of the regional balanced cross-sec­ tion [Suppe, 1983; Shaw etal., 2005]. Seismic reflection data reveals presence of basement structural wedge, south-vergent backthrust, north-vergent forethrust and some structural wedges. Stratigraphy in the ATFTB records the evolution from the extensional Achara- Trialeti Basin to Kura foreland basin of the Arabia-Eurasia collision zone. The rocks in­ volved in the deformation range from Paleo­ zoic basement rocks to Mesozoic-Neogene References Alania V., Chabukiani A., Enukidze O., Razmadze A., Sosson M., Tsereteli N., Varazanashvili O., 2017. strata. The growth of eastern Achara-Trialeti thick-skinned structures at northern part of the Lesser Caucasus, formed by basement wedge that propagated along detachm ent horizons within the cover generating thin- skinned structures. The kinematic evolution of south-vergent backthrust zone is related to northward propagating thrust wedge. The main style of deformation within the backthrust zone is a series of fault-propa­ gation folds and are developed in Cretace- ous-Paleogene strata. Frontal part of the eastern ATFTB is represented by triangle zone [Alania et al., 2016; Sosson et al., 2013, 2016]. On base of published information about his­ torical and recent earthquake data [Tsereteli et al., 2016; Varazanashvili et al., 2011], absolute ages of deformed volcanic rocks (Pliocene- Quaternary) from southern part of study area [Lebedev et al., 2007] and syntectonic units from frontal part of eastern ATFTB [Alania et al., 2016] we conclude that compressive deformation started in Middle Miocene and continues today. Acknowledgments. This work was funded by GDRI-IRG (Project #04-45) and Shota Rustaveli National Science Foundation (SRN- SF) (grants YS15_2.1.5_78 and 217942). Structural model of the eastern Achara-Trialeti fold and thrust belt using seismic reflection profiles. Teo(pu3UHecKuü xypnaA Ns 4, T. 39, 2017 81 INTERNATIONAL RESEARCH GROUP PROJECT 19th EGU General Assembly, EGU2017, proceed­ ings from the conference held 23—28 April, 2017 in Vienna, Austria, p. 5064. Alania V., ChabukianiA., ChagelishviliR., Enukidze O., Gogrichiani K., Razmadze A., Tsereteli N., 2016. Growth structures, piggyback basins and growth strata of Georgian part of Kura foreland fold and thrust belt: implication for Late Alpine kinematic evolution. In: M. Sosson, R. Stephenson, Sh. Adamia (eds.). Tectonic Evolution of the Eastern Black Sea and Caucasus. Geol. Soc. London Spec. Publ. 428. doi: 10.1144/SP428.5. Lebedev V A., Bubnov S. N., Dudauri O. Z., Vashakid- ze G. T., 2008. Geochronology of Pliocene Volcanism in the Dzhavakheti Highland (the Lesser Caucasus). Part 2: Eastern Part of the Dzhavakheti Highland. Re­ gional Geological Correlation. Stratigr. Geol. Correl. 16(is. 5), 553—574. doi: 10.1134/S0869593808050080. Naylor M., Sinclair H. D., 2008. Pro- vs. retro-foreland basins. Basin Research 20(is. 3), 285—303. doi: 10.1111/j. 1365-2117.2008.00366.x. ShawJ., Connors C., SuppeJ. (eds.), 2005. Seismic inter­ pretation of contractional fault-related folds. AAPG Studies in Geology 53, 156 p. Sosson M., Adamia Sh., Muller C., Rolland Y., Alania V, Enukidze O., Sadradze N., Hassig M., 2013. From Greater to Lesser Caucasus: new insights from sur­ face and subsurface data along a N-S trending tran­ sect (Georgia): Thick-skin versus thin-skin tecton­ ics. Darius News (3), 5—7. Sosson M., Stephenson R., Sheremet Y., Rolland Y., Ada­ mia Sh., Melkonian R., Kangarli I , Yegorova T., Avagyan A., Galoyan Gh., Danelian T., Hassig M., Meijers M., Muller C., Sahakyan L., Sadradze N., Alania V., Enukidze O., MosarJ., 2015. The Eastern Black Sea—Caucasus region during Cretaceous: new evidence to constrain its tectonic evolution. Comptes Rendu Geoscience 348,23—32. https://doi. org/10. 1016/j.crte.2015.11.002. Suppe J., 1983. Geometry and kinematics of fault-bend folding. Amer. J. Sci. 283, 684—721. doi: 10.2475/ ajs.283.7.684. TsereteliN., Tibaldi A , Alania V., GventsadseA., Enukid­ ze O., Varazanashvili O., Muller B. I. R., 2016. Ac­ tive tectonics of central-western Caucasus, Geor­ gia. Tectonophysics 691, 328—344. doi: 10.1016/j. tecto.2016.10.025. Varazanashvili O., Tsereteli N., Tsereteli E., 2011. His­ torical earthquakes in Georgia (up to 1900): source analysis and catalogue compilation. Tbilisi: Publ. House. MVP, 77 p. 82 Teo(pu3 UHecKuü xypnaA Ne 4, T. 39, 2017 https://doi SOUTH CAUCASUS GEOSCIENCES Evidence of volcanic eruptions witnessed by prehistoric man in Armenia and Argentina © A. A vagyan1, J-F. R itz2, P-H. Blard3, Kh. M eliksetian1, Ph. M unch2, P. Valla4, K. Tokhatyan5, A . Caselli6, M . M krtchyan1, T. A ta lyan1, 2017 'institute of Geological Sciences, National Academy of Sciences of Republic of Armenia, Yerevan, Armenia 2Geosciences Montpellier, Montpellier, France 3NancyUniversite, Vandoeuvre-les-Nancy, France 4Institute of Geological Sciences, University of Bern, Bern, Switzerland in s titu te of History, National Academy of Sciences of Republic of Armenia, Yerevan, Armenia 6Instituto de Investigation en Paleobiologia y Geologia Universidad Nacional de Rio Negro, Rio Negro, Argentina Prehistoric petroglyphs (rock-carvings, rock engravings) are widely spread from Europe to the Far East, Central Asia, Africa, Australia and Americas. Tens of thousands of petroglyphs have been discovered in the Armenian Highland, at elevations ranging in from 600 to 3300 m a.s.l. Strikingly, two rock- art sites, although located thousands km away from each other (Armenia in Eurasia, and Argentina in South America) exhibit well pronounced similarities in content and style. Geological evidences indicate that both areas were affected by recent volcanic eruptions. In both sites, interpretation of the pictures, as well as historical and archaeological data, strongly suggest that the engraved images may depict volcanic eruptions. In the Armenian site, situated on the bank of a small river in Syunik volcanic upland, sev­ eral petroglyphs are engraved on ca. 1.5 m diameter basalt boulders. The ancient artists have represented splashing lava fountains with volcanic bombs similar to volcanic erup­ tion of Strombolian type. Depiction of such geological phenomenon found in Armenia, is unique for the entire region, including East­ ern Turkey, Transcaucasia and Iran. This fact can be an indication, that our prehistoric an­ cestors witnessed volcanic eruption in Trans­ caucasia. There are several direct and indirect tech­ niques to date petroglyphs. The relative- comparative methods based on the analysis of content, style and carving technique with related archaeological monuments give ap­ proximate age estimations. The precise dat­ ing of petroglyphs is quite difficult, since the nature of the material to be dated is rarely suited to apply the whole variety of traditional physical dating methods. In this contribution we focus on an in­ direct dating technique, by first dating the main lava-flow surrounding the petroglyphs site. Geochronological dating techniques: cos­ mic ray exposure dating with 3He and Ar/Ar were applied in parallel, along with the clas­ sical geological and geomorphological char­ acterization. About 35 samples were collected for cosmogenic 3He exposure dating, from different lava flows. The eruption of Porak vol­ cano, situated 11 km NNW from the rock-art site, indicates an age of 28±6 Ka (la). Another source of lava flow in the Karkar plateau situ­ ated about 25 km to the SSE yields younger ages of 9.4±1.2 Ka and 5.2±0.4 Ka. Cosmogen- Teo(pii3imecKiiu xcypHOA Ns 4, T. 39, 2017 83 INTERNATIONAL RESEARCH GROUP PROJECT ic 3He dating of boulders samples at the site where the Armenian petroglyph was discov­ ered yield exposure ages comprised between 15 and 30 Ka. A global analysis including the geological, geomorphological and glaciologi- cal data supports the reliability of these new geochronological data and makes possible to establish a first time frame for the age of these petroglyphs: they were probably carved between 30 and 5 Ka. In order to obtain more precise age of the engraving, we will carry out further cosmogenic 3He dating and OSL dating (surface age) of basaltic boulders at the petroglyph site. New data on the tectonic evolution of the Khoy region, NW Iran © A. A vagyan1, A. Shahid?', M. Sosson3, L. Sahakyan4, G. Galoyan1, C. M uller1, S. Vardanyan1,3, K. B. Firouz?, D. Bosch6, T. Danelian5, G. A satryan1,5, M. M krtchyan1,6, M . A. Shokr?, 2017 'institute of Geological Sciences, National Academy of Sciences of Republic of Armenia, Yerevan, Armenia 2Geological Survey of Iran, Tehran, Iran 3Université Côte d'Azur, UMR Géoazur, CNRS, Observatoire de la Côte d'Azur, IRD, So­ phia Antipolis, France 4Nannofossils Biostratigraphy Consulting, Santok, Poland 5Universite' de Lille — Sciences et Technologies, CNRS, UMR 8198 Evo-Eco-Pale'o, Lille, France 6Université de M ontpellier INSU-CNRS, Laboratoire Géosciences, Montpellier, France The Khoy region (NW Iran) is important in the clarification of the structural frame­ work of the Alpine Belt between the Tau- rides, the Lesser Caucasus and the NW Iran belt. This area is well known for its ophiolit- ic units. We present here new stratigraphic and structural data that can be used to reconstruct the tectonic evolution of this region and then to establish connections between these belts. According to new data from nannoplankton assemblages, the ob- ducted ophiolite of the Khoy complex was thrusted over a sheared Campanian olisto- strome and lenses of amphibolite included within the contact. The obduction event is also marked by erosion of the ophiolitic unit and the deposition of conglomerates, shales, sandstones and siltstones. Poorly extended Paleocene detrital deposits cover the Campanian-Maastrichtian rocks. The Eocene formations characterize a basin filled with volcanogenic and sedimentary layers. The Middle and Upper Eocene se­ ries unconformably overlie the ophiolites, their Campanian-Maastrichtian cover and Paleocene deposits. This corresponds to a syn-orogenic basin formed after the col­ lision between Eurasia and the Taurides- Anatolides-South Armenian microplate. The Oligocene-M iocene Qom Formation with basal conglomerates unconformably covers all the earlier formations, includ­ ing the Palaeozoic formations, indicating intense shortening before its deposition. Compression deformation is currently on­ going and is manifested by numerous folds, 84 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES m ain ly w est-d ipp ing th ru sts an d reverse fau lts cu ttin g th e Q om Form ation, an d by re c en t N W -SE dex tra l strike-slip faults. This illustra tes th e con tinuous shorten ing an d up lift (w ith in ten se erosion) resu lting from th e advanced s tag e of th e collision betw een Arabia and Eurasia. The structural location of th e tecton ic un its suggests th a t th e K hoy G ondw ana-rela ted b asem en t w as p a rt of th e South A rm enian B lock an d th a t the K hoy a lloch thonous oph io lites w ere ob- d u c ted on it from the A m asia-Stepanavan- Sevan-H akari su tu re zone. Reverse and thrust tectonic heritage in the south-east intermountain Ararat depression (Armenia) © A, A vagyan1 M. Sosson2, L. Sahakyan1, S. Vardanyan1,2, Y. Sherem et2, M. M artirosyan1, C. M u lle t1, 2017 in s titu te of Geological Sciences, National Academy of Sciences of Republic of Armenia, Yerevan, Armenia 2University Côte d'Azur, UNS, CNRS, OCA, IRD Geoazur, Valbonne, France 3Université Côte d'Azur, UMR Géoazur, CNRS, Observatoire de la Côte d'Azur, IRD, Sophia Antipolis, France 3Nannofossils Biostratigraphy Consulting, Santok, Poland The studies of the south-eastern part of the Ararat basin and neighboring mountain and intermountain depressions of the Republic of Armenia, allow reevaluating of previous researches and revealing tectonic processes developed since the Late Cretaceous conti­ nental collision according to recent geody­ namic concepts. The Ararat basin structural setting and tectonic evolution investigation is perspective for hydrocarbon traps identi­ fication. The thrust and reverse stress regime of the study area was dominant during long period from collision initiation, influencing farther tectonics, complicated by strike-slip faulting. The secondary normal faults, superimposed gravitational slopes processes and selective erosion complicate moreover the overall structure pattern. These processes continue up to date. The thrust and reverse tectonics form and develop asymmetric, oblique, fold structures, cuestas with structural slops in back-limb and intensive weathered foreland in fore-limb. The result of these faults activity is seen in the Paleozoic substratum, newly discovered volcanic rocks (OIB type, probably associated with the ophiolites) outcropping from Ararat depression alluvial and lacustrine Quaternary cover. Teo(pii3imecKiiü xcypHOA Ns 4, T. 39, 2017 85 INTERNATIONAL RESEARCH GROUP PROJECT Preliminary results of paleomagnetic study of flysch sequences in Eastern Crimea mountains © V. B akhm utov, Ye. Poliachenko, T. Yegorova, A. M urovskaya, 2017 Institute of Geophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine The new dating of the Tavric flysch com­ plex at the Eastern Crimean Mountains [Sherem etetal., 2016] requires independent age determination of Crimea flysch sequenc­ es. It has been proposed to use the paleomag­ netic method taking into account that recent paleomagnetic data from Crimea had been successfully applied both for tectonics [Qinku et al., 2013] and m agnetostratigraphy [Gu- zhikov et al., 2012; Bakhmutov et al., 2016]. The key task of our study is to distinguish the paleomagnetic zones of normal and reverse polarity and their binding to the geological time scale considering the paleontological and lithological markers. But the analysis of new data of micropaleontological complexes without additional geological information, taking into account the frequent changes in magnetic polarity in the Jurassic-Early Creta­ ceous time span, shows some difficulty of this approach for our study. We have proposed another approach — to distinguish the pri­ mary magnetization and calculate paleopoles that are compared with expected reference apparent polar wander path (APWP) of Eur­ asia. Thus, we consider the main purpose of our paleomagnetic studies is the definition of paleo-latitudes of flysch sequences in Crime­ an Mountains. The second objective of our research re­ lates with study of anisotropy of magnetic susceptibility (AMS). Due to the presence of ferromagnetic particles of non-isometric form, it is assumed that magnetic structure was formed under the influence of some fac­ tors, such as bottom currents-In structural ap­ plications, AMS have been used to examine patterns of strain. An oversimplified view is that elongate ferromagnetic grains are pas­ sively rotated during deformation of rocks. Palaeomagnetic measurements were car­ ried out in the laboratory of the Institute of Geophysics of the National Academy of Sci­ ences of Ukraine in Kiev. Specimens were stepwise thermally demagnetized using an MMTD80 oven up to 600 °C. The dem agne­ tization of specimens (thermal and alternating field (AF)) and all measurements were made inside magnetically shielded rooms to mini­ mize the acquisition of present-day viscous magnetization. After each heating step, the magnetic susceptibility (k) at room tem pera­ ture was measured by a MFK1 Kappabridge to estimate possible mineralogical changes. Duplicate specimens were subjected to AF demagnetization up to 100 mT using a LDA- 3Ademagnetizer. Demagnetization steps were adjusted during thermal or AF procedures from 10° to 50 °C and 10—20 mT, respec­ tively. The natural rem anent magnetization (NRM) of specimens was measured by JR-6 spin magnetometer. Demagnetization results were processed by multicomponent analysis of demagnetization path [Kirschvink, 1980] us­ ing Remasoft 3.0 software [Chadima, Hrouda, 2006]. AMS was measured by MFK-1 Kappa­ bridge, and magnetic anisotropy parameters were calculated with the Anisoft program. During 2015—2016 field expeditions in Crimean M ountains we have examined 15 sites, and from 10 of them have collected the sandstones and argillites from flysch se­ quence of Tavric(?) series for paleomagnetic analysis. Results from 7 sites (their location is shown in Fig. 1), mainly of 2015 collection, were taken for further interpretation. 86 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES In general, the samples from different sites have different magnetic parameters and sta­ bility to thermal and AF demagnetization After removal of this weak overprint, a second component with unblocking temperatures be­ tween 300 and 400— 480 °C was calculated Crimea [Geological map| i:iwa«a Demerji Black See 20 km Privetnoye Veseloye 3 Zelenogorie Lesnoye Meganom Feodosiya Fig. 1. Sites of sampling for paleomagnetic study in Eastern Crimea Mountains. showing no common regularities. So, during next data processing and selection of mag­ netization components, some samples were excluded from the data base and were taken not suitable for further interpretation due to: 1) weak NRM (<0.001 mA/m); 2) large MAD (>10°) of selection component; 3) unstable behavior during demagnetization; 4) strong inconsistency to the rest of samples in the group. Despite the num ber of samples from each site was enough, the Q index of [Van derVoo, 1990] could not be satisfied for most sites. M any samples show dramatic increase of susceptibility during thermal dem agneti­ zation in the range 300— 400 °C. Some of the samples are characterized by a peak of the NRM at different temperatures, which indi­ cates significant changes in magnetic miner­ als behavior during heating. Usually two NRM components could be distinguished during demagnetization. Alow unblocking tem perature component, record­ ing probably a minor viscous origin, is re­ moved between 100—200 °C. The directions of this component are scattered, but the mean close to the present Earth's magnetic field. from the vector that decays linearly close to the origin. Several samples have unblocking tem perature more than 500 °C. Taken into account the high increases of susceptibility above 400 °C we can't extract the more stable component decays linearly to the origin. So the ChRM (characteristic component of rema­ nent magnetization) direction was calculated from the vector that decays linearly to the ori­ gin of the orthogonal vector plots. Five sites (numbers 1—5 in the Fig. 1) show the ChRM direction corresponding to normal polarity; after correction for fold bedding ele­ ments it becomes more scattered. Palaeomag- netic fold test show that all palaeomagnetic groups carry a post-folding remanent magne­ tization. This result confirms the Early Cre­ taceous remagnetization of sediments from other sites in Crimean M ountains reported by [Qinku et al., 2013]. The ChRM-directions of samples from sites 6 and 7, obtained from both high un­ blocking temperature and high coercive com­ ponents, show normal and reversed polarities. The correction for folding suggests that the magnetization is primary. Site 7 was dated as Геофизический журнал № 4, T. 39,2017 87 INTERNATIONAL RESEARCH GROUP PROJECT Tithonian-Berriasian boundary, the ChRM- directions have normal and reverse polarities and confirmed the result of [Guzhikov et al., 2012] about primary magnetization of Titho- nian flysch near Feodosiya. The tectonics implication of our results is not clear because of the data shortage. Meijers et al. (2010) considered the ChRM magnetization is primary and reported the Upper Jurassic palaeolatitudes in Crimea, which is inconsistent with the paleolatitudes obtained in [£inku et al., 2013], which used age and refernece palaeolatitude curve de­ rived from the APWP paths of Eurasia and Gondwana. Comparison of the average mean palaeomagnetic poles in the Triassic— Upper Jurassic units of Crimea with that ex­ pected for the Eurasian APWP, suggests an age as post-Berriasian. For the most cases the mean remagnetization directions are de- References Guzhikov A. Y., Arkad 'ev V. V., Baraboshkin E. Y., Bagae­ va M. I., Piskunov V K., Rud 'kod S. V, Perminov V A., Manikin A. G., 2012. New sedimentological, bio-, and magnetostratigraphic data on the Jurassic- Cretaceous boundary interval of eastern Crimea (Feodosiya). Stratigi. Geol. Coirel. 20,261—294. doi: 10.1134/S0869593812030045. Qinku M. C„ Hisarli Z. M„ Orbay N., Ustadmer T., Hirt A. M., Kravchenko S., Rusakov O., Sayin N., 2013. Evidence of Early Cretaceous remagnetization in the Crimean Peninsula: a palaeomagnetic study from Mesozoic rocks in the Crimean and Western Pontides, conjugate margins of the Western Black Sea. Geophys. J. Int. 195(2), 821—843. https//doi. org/10.1093/gji/ggt260. Bakhmutov V., Casellato C. E., Halasova E., Ivanova D., Rehakova D., Wimbledon W. A. P.: 2016. Bio- and magnetostratigraphy of the upper Tithonian — lower Berriasian in southern Ukraine. Abstract JURASSICA XII Conference, 4th IGCP 632 meeting and Workshop of the ICS Berriasian Working Group, April 19th—23rd, P. 20—22. KirschvinkJ. L., 1980. The least-squars line and plane and the analysis of paleomagnetic data. Geophys. fined by a single stable component. To per­ form this procedure to our data we have to involve our new results on the collection of 2016 (mainly collected in western Crimean Mountains). Now this collection is labora­ tory measured. The AMS data show typical sedimentary structure of sediments after bedding correc­ tion. The minimum axis of the AMS ellipsoid is normal to bedding, while the direction of the maximum axis is NE-SW for sites 1-5, N-S for site 6 and NW-SE for site 7. The directions of maximum axis of AMS tensor will be compared with structural and tectonophysical data from the area to define their possible connection. In the case of the shape of the AMS tensor is related to tectonic deformation, the mea­ surement of AMS in rocks of different ages will allow us to define an upper age limit for deformations. J. Roy. Astron. Soc. 62(3), 699—718. d o h lO .llll/ j . 1365246X. 1980.Ш02601 .x. Chadima M., Hrouda F., 2006. Remasoft 3.0 — a user friendly paleomagnetic data browser and analyzer. Travaux Geophysiques XXVII, 20—21. Van der Voo R., 1990. The reliability of paleomag­ netic data. Tectonophysics 184, 1—9. https://doi. org/10.1016/0040-1951(90)90116-P. Meijers M. J. M., Langereis C. G., van Hinsbergen D. J. J., Kaymakci N., Stephenson R. A., Altmer D., 2010. Jurassic-Cretaceous low paleolatitudes from the circum-Black Sea region (Crimea and Pontides) due to True Polar Wander. Earth Planet. Sei. Lett. 296, 210—226. doi: 10.1016/j.epsl.2010.04.052. Sheremet Y, SossonM., Müller C., Murovskaya A., Gin- tovO., Yegorova T, 2016. Key problems of stratigra­ phy in the Eastern Crimea Peninsula: some insights from new dating and structural data. In: M. Sosson, R. Stephenson, Sh. Adamia (Eds.). Tectonic Evolu­ tion of the Eastern Black Sea and Caucasus. Geol. Soc. London Spec. Publ., 428. http://doi.org/10.1144/ SP428.14. 88 Геофизический журнал Ne 4, T. 39, 2017 https://doi http://doi.org/10.1144/ SOUTH CAUCASUS GEOSCIENCES Mesozoic geodynamic and paleoenvironmental evolution of the Tethyan realm preserved in the Lesser Caucasus © T. D anelian1, M . S ey le t2, G . Galoyan3, M . Sossoh4, G, A satryan1,3f C. W itt2, L. Sahakyan3, A A vagyan3, A Grigoryan3, C. Cionier1, 2017 U niversité de Lille, CNRS, UMR8198 Evo-Eco-Paleo, Lille, France 2Universite' de Lille, CNRS, Université Littoral Côte d'Opale, Laboratoire d'Océanologie e t de Géosciences, Lille, France in s titu te of Geological Sciences, National Academy of Sciences of Republic of Armenia, Yerevan, Armenia 4Université Côte d'Azur, UMR Géoazur, CNRS, Sophia Antipolis, France In the Lesser Caucasus (Armenia and Karabagh; Fig. 1) can be found remnants of a Tethyan oceanic realm that existed dur­ ing the Mesozoic between Eurasia and the South-Armenian Block, a Gondwana-derived terrain considered as the eastern extension of the Tauride-Anatolide plate. The Tethyan remains in the Lesser Caucasus are part of E 44° E 45c N A 0 10 20 30 kmi N 41°- South Armenian Block !=□ Thrust Fault Normal Fault Strike slip Fault Volcanic cone □ □ Pliocene-Quaternary (volcanic and sedimentary rocks) □ □ Oligo-Miocene volcanogenic rocks □ Upper Jurassic, Cretaceous and Tertiary intrusions □ Paleocene-Eocene volcanogenic rocks □ Upper Cretaceous formations Eurasian (mainly sedimentary rocks) Margin □ Middle to Upper Jurassic volcanogenic series I Ophioiites Triassic and Jurassic series Paleozoic platform series (Devonian to Permian) Proterozoic series (gneisses-amphibolites) -N 40° N 39° E 46c Fig. 1. Geological map of the Lesser Caucasus (after [Sosson et al.( 2010], modified), including the location of the key studied areas: A — Old Sotk Pass; B — Amasia; C — Dali. reo(pu3UHecxiiu JKypHOA № 4, T. 39,2017 89 INTERNATIONAL RESEARCH GROUP PROJECT an over 2,000 km long suture zone, running through the northern part of Turkey towards Iran. As it is often the case, radiolaxites are here associated with submarine lavas that are considered to be part of an ophiolitic com­ plex. Radiolarian biochronology of radiola- rites, combined with petrographic observa­ tions and geochemical analyses of ophiolitic lavas, helps us to improve our understanding of the geodynamic and paleoenvironmental evolution of this geologically complex region. Fig. 2 synthesizes all available radio- metric and biochronological data from the Lesser Caucasus. It is likely that oceanic floor spreading was taking place during the Middle/Late Triassic between the South Ar- menian-Tauride-Anatolide plate and Eurasia. This is suggested by upper Triassic gabbros dated in Karabagh [Bogdanovski e t al., 1992] and an upper Triassic-Iiassic deep-sea sedi­ m entary sequence dated in the same area by radiolarians [Knipper e t al., 1997]. Based on 70- Maas 80- g o - La te Camp 3 oil “ Turon 100- 110- 120- Ce no m C re ta ce ou s >• Alb Apt 130- H3PU Bar Haut 140- Val Ber 150- 05«->(0 —1 160- Oxf "O 170- ■G Hath *35 § Aal 180- rckl 3 ' s Toar 190- 200- 1Z Pliens U Sinem Rhaet 210- 0> 220- Tr ia ss ii G J Nor 230- Carn 201,3 209,5 228,4 [ r r r r I Volcaniclastics i l Intrusive rocks I—-——I (gabbro, tonalité, plagiogranite) Ophiolitic breccia •••'1 Flysch F Shallow water limestone Fig. 2. Synthesis of all known ages (both biochronological and geochronological) for the ophiolitic rocks and their sedimentary cover in the Lesser Caucasus (after [Danelian et al., 2016], modified). 90 reo<pU3WiecKUÜ xcypHOA N* 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES our own investigations along the Old Sotk Pass (Fig. 1, A) radiolarian-rich cherts or sili­ ceous claystones occur as large blocks pre­ served in a mélange, together with basic ig­ neous lithologies and carbonate blocks with Triassic conodonts. Recent results point to the presence of Bajocian radiolarian cherts andAlbian siliceous claystones, both of which contain evidence of fine volcanoclastic input from subaerial volcanic activity. Based on all the radiolarian ages obtained on siliceous tuffs found in the sedimentary cover of the Amasia-Sevan-Hakari ophiolitic zone (Ama- sia, Sarinar, Old Sotk Pass) there is now good evidence that subaerial volcanic activity was underway for most of the Middle Jurassic to Lower Cretaceous (Bajocian/Bathonian to Albian). Radiolarites are in general the sedimen­ tary product of moderate levels of radiolarian productivity in a pelagic environment starved of any terrigenous or carbonate input; in the Lesser Caucasus radiolarites are either the sedimentary cover of ophiolitic lavas or inter­ calated in them. A synthesis of all currently available data suggests that radiolarian cherts accumulated more or less continuously dur­ ing the Bajocian to Cenomanian time interval in the Tethyan oceanic realm preserved in the Caucasus. Bajocian cherts are now discovered throug­ hout the Lesser Caucasus (Vedi, Sevan and Hakari ophiolites); on the contrary, Cenoma­ nian cherts are known for the moment only from Amasia (NW Armenia; Fig. 1, B). The Dali outcrop, situated east of Lake Sevan (Fig. 1, C), bears a particular geody­ namic significance. It exposes a thick basaltic sequence that overlies layered dioritic cumu­ lates intruded by a small plagiogranite body. Based on igneous mineral chemistry and bulk rock geochemistry three major basaltic groups were identified; it is likely that they are separated by thin thrust zones. The contact between the diorites and the overlying basalts is cataclastic and underlined by hydrothermal deposits of epidote and quartz; epidotization also affects the base of the basalts. Those are aphanitic tholeiites that display a clear is­ land arc signature. They are overlain in their turn by lavas transitional between tholeiitic and calk-alkaline, partly recrystallized into chlorite, albite, titanite and minor calcite and quartz. They show various textures and mineralogy (aphyric or with phenocrysts of plagioclase + augite ± amphibole or olivine + Cr-spinel ± augite) and coarse vesicles filled with calcite. The sequence ends with alkaline basalts, containing abundant phenocrysts of amphibole + diopside or diopside ± olivine and Cr-spinel, and rich in calcite replacing the mafic minerals and filling vesicles. The Dali volcanic sequence is characterized by a progressive enrichment in incompatible ele­ ments from the base to the top. In the tho- leiitic/calk-alkaline and alkaline basalts the Nb/La ratio is very variable (amphibole-rich alkali-basalts have negative Nb anomaly), and all units show evidence supporting hydrous magmas (amphibole, coarse and abundant vesicles). Overall a subduction-related envi­ ronment is suggested for the Dali magmatic rocks. The calk-alkaline lavas are overlain by radiolarites that are dated as late Tithonian- Berriasian in age [Asatryan et al., 2012]; blocks of oolitic grainstone with crinoid bioclasts in­ tegrated in the radiolarite sequence attest for the presence of shallow water carbonate sedi­ mentation in the neighboring realm. A sec­ ond interval of radiolarian cherts, intercalated between the alkaline lavas are Valanginian in age; the cherts do not contain the above mentioned limestones and are much darker in color (more Mn-rich?). Finally, the microfossil record preserved in both the uppermost part of the shallow wa­ ter carbonate sequence and overlying flysch that crop out in the Vedi area (SE of Yerevan; Fig. 1) establish that the initial stages of ob- duction of ophiolites onto the South-Arme- nian Block took place during the Cenoma­ nian (see [Danelian et al., 2014, 2016]). Teo(pii3imecKiiü xcypHOA Ns 4, T. 39, 2017 91 INTERNATIONAL RESEARCH GROUP PROJECT References Asatryan G., Danelian T., Seyler M., Sahakyan L„ Ga- loyan G., Sosson M., Avagyan A., Hubert B., Per­ son A., Vantalon S., 2012. Latest Jurassic — Early Cretaceous Radiolarian assemblages constrain epi­ sodes of submarine volcanic activity in the Tethyan oceanic realm of the Sevan ophiolites (Armenia). In: T. Danelian, S. Gorican (Eds.). Radiolarian biochro­ nology as a key to tectono-stratigraphic reconstruc­ tions. Bulletin de la Société Géologique de France 183, 319—330. doi: 10.2113/gssgfbull. 183.4.319. Bogdanovski O. G., Zakariadze G. S., Karpenko S. E, Zlo­ bin S. K., Pushhovskaya V. M., Amelin Y. V., 1992. Sm-Nd age of the gabbroids of a tholeiitic series of the ophiolites of the Sevan-Akera zone of the Lesser Caucasus. Rep. Acad. Sci. Russia 327, 566—569 (in Russian). Danelian T, Zambetakis-Lekkas A., Galoyan G„ Sos­ son M., Asatryan G., Hubert B., Grigoryan A., 2014. Reconstructing Upper Cretaceous (Cenomanian) paleoenvironments in Armenia based on Radiolaria and benthic Foraminifera; implications for the geo­ dynamic evolution of the Tethyan realm in the Lesser Caucasus. Palaeogeography, Palaeoclimatology, Pa- laeoecology413,123—132. https://doi.Org/10.1016/j. palaeo.2014.03.011. Danelian T., Asatryan G., Galoyan G., Sahakyan L„ Stepanyan J., 2016. Late Jurassic — Early Creta­ ceous radiolarian age constraints from the sedimen­ tary cover of the Amasia ophiolite (NW Armenia), at the junction between the Izmir-Ankara-Erzingan and Sevan-Hakari suture zones. Int. J. Earth Sci. (Geol Rundsch) 105(1), 67—80. doi:10.1007/s00531-015- 1228-5. KnipperA. L., Satian M. A., Bragin N. Yu., 1997. Upper Triassic-Lower Jurassic Volcanogenic and Sedimen­ tary Deposits of the Old Zod Pass (Transcaucasia). Stratigraphy, geological correlation 3, 58—65 (in Russian). Sosson M., Rolland Y., Muller C., Danelian T., Melkon- yan R., Kekelia S., Adamia S., Babazadeh V., Kan- garli T., Avagyan A., Galoyan G., Mosar J., 2010. Subductions, obduction and collision in the Lesser Caucasus (Armenia, Azerbaijan, Georgia), new in­ sights. In: M. Sosson, N. Kaymakci, R. Stephenson, F. Bergerat, V. Starostenko (eds). Sedimentary Basin Tectonics from the Black Sea and Caucasus to the Arabian Platform. Geol. Soc. London Spec. Publ. 340, 329—352. The obduction process: What extent? What timing? What cause(s)? The study of the northern branch of Neotethys in Anatolia and the Lesser Caucasus (Turkey and Armenia) © M . H âssig1, M. Sosson2, Y. Rolland2, 2017 d ep artm en t of Earth Sciences, University of Geneva, Geneva, Switzerland 2Université Côte d'Azur, Géoazur, UNS , CNRS, IRD, Observatoire de la Côte d'Azur, Sophia Antipolis, France Worldwide within mountain ranges the presence of slivers of preserved oceanic lith­ osphere known as ophiolites evidence a tec­ tonic process responsible for their emplace­ ment on top of the continental crust called obduction. The first order anomaly inherent to this phenomenon is that dense rocks (p>3) end up on top of less dense rocks (p«2.7). The driving forces responsible and consequent/ accompanying processes for such a tectonic oddity remain uncertain. The ophiolites of the Lesser Caucasus and NE Anatolia are prime examples of this phenomenon with tectonic transport (> 150 km) of fragments of oceanic lithosphere towards the south on top of the South Armenian Block-Tauride-Anatolide Platform along the entire continental marge (>1000 km) (Fig. 1). The multidisciplinary ap­ proach used throughout the study of these ophiolites yielded clues specifying the evolu­ tion of the Northern Neotethys Ocean before and around the time of ophiolite emplace- 92 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 https://doi.Org/10.1016/j SOUTH CAUCASUS GEOSCIENCES 40°E Ophiolite outcrops 42°E Former extent of obduction 44°E 46°E 48°E Suture zone 50°E Main thrust Cenozoic thrusts Araks Vedi Obduction contact Eurasian margin Sevan Lake Sevan-Akera suture basin и__ , , ^ Plio-quaternary basin an d ophiolites Crystalline basement 10 km 50 km Fig. 1. Tectonic map of the Middle East-Caucasus area, showing the main blocks and suture zones, and corre­ sponding crustal-scale section showing the obduction, after [Hassig et al.r 2013]: EAF — East Anatolian Fault; I AES — Izmir—Ankara—Erzincan Suture; KB — Kirshehir Block; MM — Menderes Massif; NALC — North-East Anatolia—Lesser Caucasus domain (zone of ophiolite obduction); SAB — South Armenian Block; V — volcanic arc of Eurasian margin of Pontides. * position of cross-section (below). Lower panel: Upper-crustal-scale geological section of the NALC showing the geometry of the obduction front propagated towards the south and its rooting into the Sevan Akera suture to the north, below the Eurasian margin (see [Rolland et al., 2012]). Геофизический журнал № 4, T. 39,2017 93 INTERNATIONAL RESEARCH GROUP PROJECT SAB-TAP N Lesser Caucasus-Pontides Northern ,̂ rc OlB-type magmatism neotethys E u ra s ia n / U iv la rg in v 1 Thrust faults Mantle upwelling Clastic sedimentation 'Amphibolites/ Gravity sliding (passive obduction) 90 Mac - _ __ Gravity sliding (passive obductiojiJ. Normal faults _85Ma __ _ Fig. 2. Conceptual model of the obduction process in the NALC: a — situation in the Early Cretaceous showing the convergence of SAB—TAP (South Armenian Block—Taurides Anatolides) with the Eurasian margin, the onset of mantle upwelling and heating of the oceanic lithosphere at 115 Ma, b — triggering of obduction, due to the blocking of the northern subduction zone and the increase in buoyancy of the oceanic lithosphere, c— thickening of the continental crust below the obduction, erosion and the onset of passive obduction [Lagabrielle et al., 2013] by gravity sliding of the ophiolites on the flexural basin, d — transition from a contractional to an extensional regime due to renewed subduction. Mantle thinning and withdrawal leads to the exhumation of the continental crust. m ent (90 Ma), consequently the obduction event. Our findings strongly suggest common emplacement of all the ophiolites of the study area as a thrust sheet of Middle Jurassic oce­ anic lithosphere, ~70—80 Ma old a t obduc­ tion onset. This would be one of the biggest preserved ophiolite nappe complexes in the world (outcropping in a mountain range). Numerical modelling validated, firstly; the hypothesis that emplacement of such an ophi- olitic nappe is due to particular thermal con­ ditions. For old oceanic lithosphere to obduct it needs to be in a thermal state close to that of young oceanic lithosphere (0—40 km thick). Secondly, numerical modelling showed that the progression of obduction over a great dis­ tance and current position of the ophiolites far over the continental margin could be ex­ plained by post-compression extension. This switch in tectonic regime is responsible for the thinning of the ophiolitic nappe, under­ plating of underthrusted continental litho­ sphere and exhumation of continental crust. Thermal rejuvenation is supposed for the ophiolites of the Caucasus s.l. argued by al­ kaline lavas emplaced on the sea floor prior to the obduction event during the Late Cre­ taceous (117 Ma). The resulting seamounts and/or oceanic plateaus of this magmatism would then have blocked the north-dipping subduction zone father north under Eurasia upon their entree and this until the end of the obduction event. The obduction event on the South Armenian Block—Tauride—Anatolide Platform is synchronous along the Eurasian margin from the Pontides to the Somkheto- Karabakh. Reactivation of the north-dipping subduction zone under Eurasia is compat­ ible with traction on the obducted oceanic lithosphere responsible for its mantle thin­ 94 reo<pU3imecKUÜ ÆypaaA A& 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES ning, continental lithospheric underplating and continental crust exhumation. Thus the propagation of thin obductions according to the «flake tectonics» concept over an eclog- References Hâssig M., Rolland Y, Sosson M., Galoyan G., Sahaky- an L, Topuz G., Çelik O. E, Avagyan A., Müller C., 2013. Linking the NE Anatolian and Lesser Cauca­ sus ophiolites: evidence for large scale obduction of oceanic crust and implications for the formation of the Lesser Caucasus-Pontides Arc. Geodin. Acta 26, 311—330. http://dx.doi.org/10.1080/0985311L2 013.877236. Lagabrielle Y, Chauvet A., Ulrich M., Guillot S., 2013. Passive obduction and gravity-driven emplacement ite-free underthrusted continental margin can result from a combination of reheating of the oceanic lithosphere and far-field plate kine­ matics (Fig. 2). of large ophiolitic sheets: the New Caledonia ophio- lite (SW Pacific) as a case study? Bull. Soc. Géol. Ft. 184, 545—556. doi: 10.2113/gssgfbull. 184.6.545. Rolland Y., Perincek D., Kaymakci N., Sosson M., Bar­ rier E., Avagyan A., 2012. Evidence for~80—75 Ma subduction jump during Anatolide—Tauride—Ar­ menian block accretion and ~48 Ma Arabia-Eur- asia collision in Lesser Caucasus-East Anatolia. J. Geodyn. 56-57, 76—85. https://doi.Org/10.1016/j. jog.2011.08.006. Ore-forming processes in basite-ultrabasite complexes of ophiolites of the Lesser Caucasus © A. Ism ail-zade, T. Kangarli, 2017 Institute of Geology and Geophysics, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan The basite-ultrabasite complex of ophiol­ ites was formed in the result of many-stage m antle-crust evolution of mantle substance. All this was stipulated by different genesis processes forming deposits of chromite, gold and mercury Magmatic chromites are connected with mantle ultrabasite part of ophiolite profile formed in the process of oceanic crust forma­ tion accompanied with gabbro and tholeitic vol- canism. Mantle differentiation of ultrabasite substance in the process of its high-tempera­ ture viscous displacement was one of the fac­ tors of chromite isolation. Gold deposits in basite-ultrabasites of ophiolites are related to autometamorphic process and lay on hydro- thermal metasomatic processes. Combination of these processes caused extraction of gold out of ultrabasites at early mantle metamor­ phism and is reaccumulation under the hydro- thermal solutions of gabbro-plagiogranite intrusive. Mercury deposits in ultrabasites complex are of hydrothermal type. Deep faults of this belt activation in postcollision period serve as leading channels of Mio- Pliocene acid volcanism and mercury-con- tent hydrothermal solutions. Serpentinized peridotites in these processes played the role of a screen. However regeneration of early deeper deposits could also occur. Different types of ore-forming activity connected with forming of ophiolites reflect the complex spatial correlation between the processes of ore formation, evolu­ tion of ultrabasits and geodynamical regime of the region. reo(pu3unecKuü xypnoA Ns 4, T. 39, 2017 95 http://dx.doi.org/10.1080/0985311L2 https://doi.Org/10.1016/j INTERNATIONAL RESEARCH GROUP PROJECT Petrology and geochemistry of basaltic series in Cenozoic volcanic belts of Gaucasus © A Ism ail-zade, T. Kangarli, 2017 Institute of Geology and Geophysics, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan Alpine stage of tectonic-m agm atic d e ­ velopm ent of C aucasus is considered in sphere of com plete geodynam ic process caused by the correlation of Tethys oce­ anic crust w ith continental m argins of an- Fig. 1. Normalized multicomponent diagram of the volcanic rock complexes of the Middle Eocene (Yere- van-Ordubad zone): 1 — toleitic basalt (13); 2 — calc- alkaline basalt (14); 3 — Trakhibasalt (15). cien t lithospheric p la tes of Eurasia and Afroarabia. As M esozoic-Cenozoic p e ­ riod is characterized by th e manifestation Fig. 2. Normalized multicomponent diagram of the volcanic rock complexes of the Middle Eocene (Talish, Adjara-Trialety and Geychay-Akerin zones): 1 — tole­ itic basalt, middle (16); 2 — sub-alkalinetrekhibasalt, middle Eocene (17); 3 — alkaline melafonolite, Oligo­ cène—Miocene (18). 96 reo<pU3WiecKUÜ xcypHOA N* 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES of riftogenic and island arc volcanism, so Cenozoic one is noted by the regim e com­ bination of active continental margins com­ pleted by continental rift with activation re­ gime for area of com pleted folding. Three active phases can be d istingu ished for Cenozoic volcanism fully m anifestated in Lesser C aucasus: 1) Eocene; 2) Miocene— Early Pliocene; 3) Late Pliocene—Quater­ nary (Fig. 1—4). At Paleogene stage there was formation of two symmetrically situated volcanic belts on both continental margins which are close according to their content and consist of sep­ arated by Zangazur geosuture zone. Basalts of these belts with low content of Kr Rb, at La/Yb = 3 and not so high of Ni, Cr corre­ spond to tholeitic basalts of island arcs. This stage includes two regions of alkaline basal- HRb K La Nd Hf Ti Yb Co Crh—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—h Ba Sr Ce Sm Eu Tb Lu Ni H Fig. 3. Normalized multicomponent diagram of the volcanic rock complexes of the Neogene (Yerevan-Or- dubadzone): 1— andesidasite (19); 2 — andesite (20). toid volcanism corresponding to inside arc riftogenesis with basalt with La/Yb = 11-5-15 and high content of Kr Rb, Ni, Cr. At Neogene stage volcanism is manifestat­ ed in two series: calcalcali, andesite-dacite- rhyolite developed in Paleogene depression of both continental margins and trachybasalt- phonolite developed within rises. M iddle members of the first series (La/Yb = 30-S-40) are characterized by high K, Rb, Ba, Sr, light REE, lowNi, Co, Cr and correspond to residual melting in Paleogene chambers, are subjected to differentiation in the crust. In subalkaline series the middle differentiation on high K, Rb, Ba, Sr, light REE, Co, Ni, Cr correspond to basalts of riftogenic zones. Rb K La Nd Hf Ti Yb Co Cr i— t— i— i— i— i— i— i— i— i— i— i— i— i— i— i— i— i— i Ba Sr Ce Sm Eu Tb Lu Ni Fig. 4. Normalized multicomponent diagram of the vol­ canic rock complexes of the Late Pliocene - Holocene: 1 — low potassium dolente, Trans-Caucasus rise (21); 2 — trakhiandesibasal, Gegam (22); 3 — trakhiandesi- basal, Kelbajar (23); 4 — basanite, Kafan, Zangezur su­ ture zone (24). reo(pu3UHecxiiu JKypHOA № 4, T. 39,2017 97 INTERNATIONAL RESEARCH GROUP PROJECT Fig. 5. Correlation of rare elements in Mz (a) and KZ (b, c) in basites of the Lesser Caucasus. At Late Pliocene—Q uarternary stage volcanism is p resen ted by tholeitic (La/Yb=7.5), subalkaline (La/Yb=40,5) and alkaline (La/Yb=66-j-70) basalts which are characterized by the increazing accu­ mulation of Kr Rbr Bar Srr light REEr Ni, Co, Cr. In formation of them one can observe the change of fusion level of magmatic melt from mantle for the first (tholeitic basalt, ol­ ivine basanites) to the mantle crustal, inter­ mediate — trachyandesite-basalts (Fig. 5). Change of low-potassic low-Ti, deplited by light REE of Early Cenozoic volcanites by rather enriched light REE and elements with large ionium radii of Late Cenozoic volcanites can be connected with the change of geodin- amics of the region from the active continental margins to activized area of completed old- ing, accompanied by the rise of fusion front, transported from depleted abnormal mantle in the sphere of metasomatically overdone up­ per mantle in the base of lithospheric plates. Active geodynamics of the Caucasus © F. Kadirov, S. M am m adov, R. Safarov, 2017 Institute of Geology and Geophysics, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan We present GPS observations of crustal deformation in the Africa-Arabia-Eurasia zone of plate interaction, and use these observations to constrain broad-scale tec­ tonic processes within the collision zone of the Arabian and Eurasian plates. Within this plate tectonics context, we exam­ ine deformation of the Caucasus system (Lesser and Greater Caucasus and inter­ vening Caucasian Isthmus) and show that most crustal shortening in the collision zone is accommodated by the Greater Caucasus Fold-and-Thrust Belt (GCFTB) along the southern edge of the Greater Caucasus M ountains (Fig. 1). The eastern GCFTB appears to bifur­ cate west of Baku, with one branch follow­ ing the accurate geometry of the Greater Caucasus, turning towards the south and traversing the Neftchala Peninsula. Asec- ond branch (or branches) may extend di­ rectly into the Caspian Sea south of Baku, 98 reo<pU3WiecKUÜ xcypHOA N* 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES 44°N 42°N 40°N 38°N 36°N 40°E 42°E 44°E 46°E 48°E 50°E Fig. 1. GPS velocities and 95 % confidence ellipses w.r.t. (with respect to) Eurasia for the eastern AR-EU collision zone. likely connecting to the Central Caspian Seismic Zone (CCSZ). We model defor­ mation in terms of a locked thrust fault that coincides in general with the main surface trace of the GCFTB. We consider two end-member models, each of which tests the likelihood of one or other of the branches being the dominant cause of ob­ served deformation (Fig. 2). Our models indicate that strain is ac­ tively accumulating on the fault along the ~200 km segm ent of the fault west of Baku (approximately between longitudes 47—49°E). Parts of this segm ent of the fault broke in major earthquakes histori­ cally (1191, 1859, 1902) suggesting that significant future earthquakes (M~6-s-7) are likely on the central and western seg­ m ent of the fault. We observe a similar deformation pattern across the eastern end of the GCFTB along a profile cross­ ing the Kur Depression and Greater Cau­ casus M ountains in the vicinity of Baku. Along this eastern segment, a branch of the fault changes from a NW-SE striking thrust to an N-S oriented strike-slip fault reo(pu3UHecxiiu JKypHOA № 4, T. 39,2017 99 INTERNATIONAL RESEARCH GROUP PROJECT 0 El ® 0 © 1 12 10 - 8A l 6 : a ^ 2 0 -2 -60 -40 -20 0 20 40 60 80 100 Distance along profi e / kn [D] (d) Fig. 2. Plots of transverse (A) and parallel (B-E) components of velocities versus distance along the profilesshown in Fig. 1. (or in multiple splays). Similar deforma­ tion pattern along the eastern and central GCFTB segments raises the possibility that major earthquakes may also occur in eastern Azerbaijan. However, the eastern segment of the GCFTB has no record of wo reo<pU3WiecKUÜ xcypHOA N* 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES large historic earthquakes, and is char­ acterized by thick, highly saturated and over-pressured sediments within the Kur Depression and adjacent Caspian Basin that may inhibit elastic strain accumula­ tion in favour of fault creep, and/or dis­ tributed faulting and folding. Thus, while our analyses suggest that large earthquakes are likely in central and western Azerbaijan, it is still uncer­ tain whether significant earthquakes are also likely along the eastern segment, and on which structure. Ongoing and future focused studies of active deforma­ tion promise to shed further light on the tectonics and earthquake hazards in this highly populated and developed part of Azerbaijan. Active tectonics and focal mechanisms of earthquakes in the pseudosubduction active zone of the North- and South-Caucasus microplates (within Azerbaijan) © T. Kangarli, F. A liyev, A . A liyev, U. Vahabov, 2017 Institute of Geology and Geophysics, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan The Greater Caucasus was formed dur­ ing the last stage of tectogenesis in a geo­ dynamic environment of the lateral com­ pression, peculiar to the zone of pseudo­ subduction between Northern and South­ ern Caucasian continental microplates. Its present structure was formed as a result of horizontal movements during different phases and sub-phases of Alpine tecto­ genesis (from late Cimmerian to Walakh- ian). The Greater Caucasus is generally considered as a zone where (along Zangi deformation) the insular arc formations of the Northern edge of the South Caucasian microplate thrust under thick Mesozoic- Cenozoic complex composed of marginal sea deposits of Greater Caucasus. The last, in its turn, has been pushed beneath the North-Caucasus continental margin of the Scythian plate (Epihersinian plat­ form) along the Main Caucasus Thrust. As a result of the underthrusting, the ac­ cretion prism compressed between the indicated faults, was formed. Within the territory of Azerbaijan the tectonic stratification of the Greater Cau­ casus marginal sea alpine complex is dis­ tinguished in the structure of the South­ ern Slope zone (megazone). W ithin the megazone different-scale and different- age cover-thrust complexes — Tufan, Sa- rybash, Talachay-Duruja, Zagatala-Dibrar and Govdagh-Sumgayit— were identified and described. Allocated beneath accre­ tionary prism of the Southern Slope, the autochthonous bedding is presented by Mesozoic-Cenozoic complex of the north­ ern Vandam-Gobustan margin (mega­ zone) of the South-Caucasus microplate, which is in its' turn crushed and lensed into southward shifted tectonic micro­ plates gently overlapping the northern flank of Kura flexure along Ganykh-Ay- richay-Alat thrust. Formation of folded-cover structure of the Greater Caucasus accretionary prism is studied within the geodynamic model of intracontinental C-subduction Teo(pii3imecKiiü xcypHOA Ns 4, T. 39, 2017 101 INTERNATIONAL RESEARCH GROUP PROJECT (pseudo-subduction) under pressure of the advancing northward Arabian plate. This concept for the Caspian-Caucasian- Black Sea region is justified by a number of researches of the region. The described process continues up at the present stage of alpine tectogenesis as demonstrated by real-time GPS survey. Monitoring of the distribution of horizontal shift velocity vectors, produced during 1998—2016 by GPS geodesic stations in Azerbaijan, in­ dicates considerable (up to 29 mm/year) north-northwestward shifting velocity of the southwestern and central parts of South-Caucasus microplate, including territories of the southeastern part of Less­ er Caucasus, Kura depression and Talysh. At the same time, within the microplate's northeastern flange confined to Vandam- Gobustan megazone of Greater Caucasus, velocity vectors reduce by 6—13 mm/year, while further to the north, on a hanging wall of Kbaad-Zangi deep underthrust, e.g. directly within the boundaries of ac­ cretionary prism the velocity becomes as low as 0—6 mm/year (2010—2016 data). In general, the belt's earth crust reduc­ tion is estimated as 4— 10 mm/year. This phenomenon reflects consecutive accu­ mulation of elastic deformations within pseudo-subduction interaction zones between structures of the northern flank of South-Caucasus microplate (Vandam- Gobustan megazone) and the accretion­ ary prism of Greater Caucasus. The ongoing pseudo-subduction is in­ dicated by unevenly distributed seismici­ ty by depths (seismic levels of 2—6,8—12, 17—22 and 25—45 km): distribution anal­ ysis of the earthquake cores evidences the existence of structural-dynamic interre­ lation between them and the subvertical and subhorizontal contacts in the earth crust. Horizontal and vertical seismic zon­ ality is explained from the viewpoint of block divisibility and tectonic stratifica­ tion of the earth crust, within the structure of which the earthquake cores are con­ fined mainly to an intersection knots of the ruptures with various strike, or to the platitudes of deep tectonic failures and lateral shifts along unstable contacts of the substantial complexes with different competency. Types of focal mechanisms in general correspond to the understanding of geo­ dynamics of the microplates convergent borders, where the entire range of focal mechanisms, from normal-fault to up­ thrust, is observed. At the contemporary stage of tectogenesis the maximum seis­ mic activity is indicated in structures of the northern flank of South-Caucasus mi­ croplate controlled by Ganykh-Ayrichay- Alat deep overthrust of the «general Cau­ casus strike» in the west, and submeridi­ onal right-slip zone of the West-Caspian fault in the east of the Azerbaijani part of Greater Caucasus. Under lateral compression the small- scale blocks that constitute the earth crust in this region become reason for the cre­ ation of transpressive deformations, which combine shift movements along limiting transversal deformations with compres­ sion structures to include general Cau­ casus strike ruptures. Such regime leads to the generation of multiple concentra­ tion areas of the elastic deformations con­ fined to mentioned dislocations and their articulation knots. It is just the exceeded ultimate strength of the rocks that causes energy discharge and brittle destructions (according to stick-slip mechanism) in such tectonically weakened regions of the southern slope of Azerbaijani part of Greater Caucasus. At the contemporary stage of tecto­ genesis the maximum seismic activity is indicated within northern flank of South- Caucasus microplate controlled by Gan- ykh-Ayrichay-Alat deep overthrust of the 102 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES Balakan Q ; Legend Guton ^ 3 6 4 & • kf I l f rulin' faillis seen on surface ........... buried anti-Caucasian direction __ _ buried Caucasian direction Lagodckhi E arth q m ik rs M > 5.0 Y 15 Suhmeridianal faults: 1 - Khimrikh - Khalatala 2 - Tinovroso - Kadak siHMatmids faults: 3 -Bufanygchay- Verkbiyan ^-M azym garyshan -Katekh Faults of North - East trend: 4 - Balakan 5 - Katekhchay 6 - Zagatala 7 - Meshlesh & -T alachay- Lalali 9 - Kish 1 0 - Shaki 11 - Gohmud - Salyakhan Longitudinal faults: 13 — Zangi 14 - Shambul - Ismayilli 15 - Dashuz - Amirvan Earthquake clusters: I - Balakan II -Zagatala III - Shaki Fig. 1. Allocation of earthquake foci zones of the North-Western Azerbaijan. «general Caucasus strike» in the west, and submeridional right-slip zone of the West- Caspian fault in the east of the Azerbai­ jani part of Greater Caucasus. This fact is particularly proved by earthquakes which took place in M ay and December, 2012 in Zagatala, Shaki and Balakan (Fig. 1). Zagatala earthquake. Focal zone of the earthquake is confined to a complex intersection knot of different strike faults, and is located in Pre-Jurassic basement. The main shock is related with activity of Zagatala fault with northwestern strike which caused activation of connected dis­ locations. Balakan earthquake. Focal zone of the earthquake is confined to a complex in­ tersection knot of the faults with various strikes, and is located in the upper part of Pre-Jurassic basement. Seismic event is mainly related to activity of Khimrikh- Khalatala fault with submeridional strike, which in turn led to activation of connect­ ed northeastern Balakan and sublatitudi- nal Mazymgaryshan-Katekh dislocations. Discharge of seismic energy occurred in most granulated zones confined to the in­ tersection knots of these dislocations with faults of the general Caucasus strike. Shaki earthquake. The focal zone of the earthquake located in the upper part of Pre-Jurassic basement. Seismic event is connected with activity of subvertical faults with northeastern strike. Discharge Teo(pu3UHecKiiu JKypHOA № 4, T. 39,2017 103 INTERNATIONAL RESEARCH GROUP PROJECT of seismic energy occurred in most granu­ lated zones confined to the intersection knots of these dislocations with faults of the general Caucasus trace. On the basis of the spatial-temporal analysis of the earthquake foci distribu­ tion with M > 3 for the instrumental pe­ riod of observations (1902—2013), we es­ tablished the dynamics of seismic activity on the southern slope zone of the Greater Caucasus the following are defined: - the epicenters spatial distribution demonstrates that the above mentioned events are confined to the transverse (northwestern, northeastern, and sub­ meridional strike) disjunctive disloca­ tions. However, epicentral zones are of a General Caucasus strike, dislocated along and to the north of the deep upthrust. Both transverse and longitudinal dislocations are mapped by a complex of seismic and electrical reconnaissance methods. They are characterized as a natural southern ex­ tension of the fault-slip type disjunctive zones that outcrop in the mountainous area where structural-substantial complexes of an accretionary zone come to the surface; - focal mechanisms of events in the separate groups reveal different, mainly close-to-vertical, planes of fault and fault- slip type movements in the earthquake foci. Only in four cases were strictly up­ thrust and upthrust-overthrust type move­ ments established; - hypocenters of major seismic impacts (M=4.5h-5.7) and the absolute majority of aftershocks are confined to the surface of the pre-Jurassic basem ent or its depths (up to 20 km); - most of hypocenters are confined to a sloping strip which subsides in the north­ ern azimuths, identified with the zone of Ganykh-Ayrichay-Alat deep overthrust and its flakes; - in general, the seismic activity of a mentioned period is explained by accu­ mulation of lateral compression stresses and their later discharge in an under­ thrust articulation line from the Middle Kur and Vandam tectonic zones along the Ganykh-Ayrichay-Alat deep overthrust; - lateral compression first contributed to the creation of transpressional failures along the displacement planes of vari­ ous-strike transverse dislocations, and the energy discharge in most granulated and weakened areas was confined to the intersection knots of these dislocations between each other and with the deep overthrust with its northern rear flakes. Active tectonics and focal mechanisms of earthquakes in the pseudosubduction active zone of the North and South Caucasus microplates (within Azerbaijan) © T. Kangarli, F. A liyev, A . A liyev, Z. M urtuzov, 2017 Institute of Geology and Geophysics, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan The Greater Caucasus was formed during the last stage of the tectogenesis in a geody­ namic environment of the lateral compression, peculiar to the zone of pseudo-subduction be­ tween the Northern and Southern Caucasian continental microplates. Its present structure 104 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES was formed as a result of horizontal move­ ments during different phases and sub-phases of Alpine tectogenesis (from late Cimmerian to Valakhian). The Greater Caucasus is gen­ erally considered as a zone (along Zangi de­ formation) where the insular arc formations of the Northern edge of the South Caucasian microplate thrust under thick Meso-Cenozoic complex composed of marginal sea deposits of Greater Caucasus. The latter in its turn, has been pushed beneath the North-Cauca- sus continental margin of the Scythian plate along the Main Caucasus Thrust. As a result of the underthrusting, the accretion prism compressed between the indicated faults, was formed. W ithin the territory of Azerbaijan the tec­ tonic stratification of the Greater Caucasus marginal sea alpine complex is distinguished in the structure of the Southern Slope zone (megazone). W ithin the megazone different- scale and different-age cover thrust com­ plexes — Tfanskiy, Sarybashsky, Talachay- Durudzhinskiy, Zagatala-Dibrar and Govdag- Sumgayit — were identified and described. Allocated beneath the accretionary prism of the Southern Slope, the autochthonous bed­ ding is presented by Meso-Cenozoic complex of the northern Vandam-Gobustan margin (megazone) of the South-Caucasian micro­ plate, which, in its turn, crushed and lensed into southward shifted tectonic microplates gently overlapping the northern flank of Kura flexure along the Ganykh-Ayrichay-Alyat thrust. Formation of the folded-cover structure of the Greater Caucasus accretionary prism is studied within the geodynamic model of intracontinental S-subduction (pseudo-sub- duction) under pressure of the advancing northward Arabian Plate. This concept for the South-Caspian-Caucasian-Black Sea region is justified by a number of researches of the study region. The proposed process continues up to the present stage of Alpine tectogenesis as it follows from real-time GPS survey [Kad- irov et al., 2008]. Monitoring of distribution of horizontal shift velocity vectors, produced during 1998—2012 by GPS geodetic stations in Azerbaijan, indicates considerable (up to 17— 18 mm/year) north-northwestward shift­ ing velocity of the southwestern and central portions of the South Caucasus microplate, including the areas of the southeastern part of the Lesser Caucasus, Kura depression and Talysh. At the same time, within the micro­ plate northeastern flange confined to Van­ dam-Gobustan megazone of Greater Cau­ casus, velocity vectors reduce by 8— 12 mm/ year, while further north, on a hanging wall of the Kbaad-Zangi deep underthrust, e.g. directly within the boundaries of the accre­ tionary prism, the velocity becomes as low as 0—4 mm/year (2010—2012 data). As a whole the Earth's crust contraction within this belt is estimated equal to 4— 10 mm/year. This phenomenon reflects consecutive accumulation of elastic deformations within pseudo-subduction interaction zones be­ tween structures of the northern flank of the South Caucasus microplate (Vandam-Gobust­ an megazone) and the accretion prism of the Greater Caucasus. The ongoing pseudo-subduction is indi­ cated by unevenly distributed seismicity by depths (at 2—6, 8— 12,17—22 and 25—45 km depth): distribution analysis of the earth­ quake foci evidences the existence of struc­ tural-dynamic relation between them and the subvertical and subhorizontal contacts in the Earth's crust. Horizontal and vertical seismic zoning is explained from the viewpoint of block structure and tectonic stratification of the crust, where the earthquake foci are con­ fined mainly to intersection nodes of faults of different strike, or to the planes of deep tec­ tonic faults and lateral displacements along unstable contacts of substantial complexes with different competency. Types of focal mechanisms in general cor­ respond to the understanding of geodynam­ ics at the convergent margins of microplates, where the whole range of focal mechanisms, from normal faults to overthrusts, is observed. Under lateral compression the small-scale blocks that constitute the crust in this region become a reason for creation of transpres- sive deformations, which combine strike-slip movements along transversal faults limiting the blocks with compression structures to Teo(pii3imecKiiü xcypHOA Ns 4, T. 39, 2017 105 INTERNATIONAL RESEARCH GROUP PROJECT include general Caucasus strike faults. Such a regime leads to generation of multiple places of localization of elastic deformations confined to mentioned dislocations and their articulation nodes. It is just the exceeded ulti­ mate strength of the rocks that causes energy discharge and brittle deformations (according to strike-slip mechanism) in such tectonically weakened regions of the southern slope of Azerbaijan part of the Greater Caucasus. At the contemporary stage of tectogene- sis the maximum seismic activity is released within the structures at the northern flank of South Caucasus microplate controlled by Ganikh-Ayrichay-Alyat deep overthrust of «general Caucasus strike» in the west, and by ~N-S right-slip zone of the West-Caspian fault in the east of the Azerbaijan part of the Greater Caucasus. This fact is particularly proved by the earthquakes which occurred in May and De­ cember, 2012 in Zagatala, Sheki and Balakan. Zagatala earthquake. Focal zone of the earthquake is confined to a complex inter­ section knot of different strike faults, and is located in the Pre-Jurassic basement. The main seismic event is related with activity of Zagatala fault of northwestern strike which caused activation of connected dislocations. Balakan earthquake. Focal zone of the earthquake is confined to a complex intersec­ tion knot of the faults with various strikes, and is located in the upper part of the Pre-Jurassic basement. Seismic event is mainly related to activity of Khimrikh-Khalatala fault of ~N-S, strike, which, in turn led to activation of re­ lated N-E Balakan and ~ E-W Mazimgarishan- Katekh faults. Release of seismic energy oc­ curred in most granulated zones confined to the intersection nodes of these dislocations with faults of general Caucasus strike. Sheki earthquake. The focal zone of the earthquake is located in the upper part of the Pre-Jurassic basement. Seismic event relates with activity of subvertical faults of NE strike. Discharge of seismic energy occurred in most granulated zones confined to the intersection knots of these dislocations with faults of the general Caucasus trace. Study of the space-time sequence of the earthquakes of different magnitudes in each seismic zone allows us to draw the following conclusions: - the spatial distribution of foci demon­ strates that the earthquakes are confined to the transverse (NW, NE and ~NS strike) faults. However, the epicentral zones have a general strike similar to that of Greater Cau­ casus, dislocated along and to the north of the deep overthrust. Both transverse and longitu­ dinal dislocations are mapped by seismic and electrical surveys. They represent the south­ ern extension of the fault zones that outcrop in the mountain area where accretion zone rock complexes come to the surface; - focal mechanisms of events of separate groups reveal different, mainly near vertical, planes of fault in the earthquake foci. Only in four cases there were determined the over­ thrusts strictly directed upwards; - the foci of major strong earthquakes (M=4.5-h5.7) and the majority of the after­ shocks are confined to the surface of the pre-Jurassic basem ent at the depths down to 20 km; - most of foci are confined to a sloping strip which subsides in the northern direction, identified with the zone of Ganikh-Ayrichay- Alyat deep overthrust and its flakes; - in general, the seismic activity of the men­ tioned period is explained by accumulation of lateral compression stresses and their later discharge in the junction zone of the Middle Kura and Vandam tectonic zones along the Ganikh-Ayrichay-Alyat deep overthrust; - lateral compression first contributed to the creation of transpressional failures along the displacement planes of various strike transverse dislocations, and the energy dis­ charge in most granulated and weakened areas was confined to the intersection nodes of these dislocations between each other and with the deep overthrust with its' northern flakes. 106 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES References Kadirov E, Mammadov S., Reilinger R., McCIusky S., 2008. Some new data on modem tectonic deforma­ tion and active faulting in Azerbaijan (according to Global Positioning System Measurements). Proceed­ ings Azerbaijan National Academy of Sciences. The Sciences of Earth (1), 82—88. Philip H., Cistemas A., Gvisiani A., Gorshkov A., 1989. The Caucasus: An actual example of the initial stag­ es of continental collision. Tectonophysics 161(1-2), 1—21. doi: 10.1016/0040-1951(89)90297-7. Paleo- and recent stress regimes of the Crimea Mountains based on micro- and macroscale tectonic analysis and earthquakes focal mechanisms © A. M urovskaya1, Ye. Sherem et2, M. Sosson2, J.-C. H ippolyte3, O. G intov1, T. Yegorova1, 2017 in s titu te of Geophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine 2Université Côte d'Azur, UMR Géoazur, CNRS, Sophia Antipolis, France 3Aix-Marseille Université, Aix-en-Provence, France The Crimea M ountains (CM) belongs to the northern branch of the Alpine Belt. Being the northwestern continuation of the Great­ er Caucasus (GC) and a part of the inverted northern margin of the Black Sea (BS), the CM region shows the similarities in structural development of both the domains, implying the common tectonic evolution of the GC — Eastern BS area. In the current study, we focus on the Meso- Cenozoic time-span of tectonic evolution of the CM and the adjacent BS margin in order to define paleo- and recent stress regimes alternated during its tectonic history, based on the recent geological field observations, the results of structural analysis, the micro- tectonic data and the analysis of focal mecha­ nisms of the earthquakes. Thus, the main pur­ pose of our study is to find and investigate the correlation between the stress field and the large-scale deformation structures with subsequent determination of major tectonic events. The Cenozoic compression. The major direction of the shortening during the Ce­ nozoic was defined in regards of main ori­ entation (trends) of the thrusts and fold axis developed in the Eastern CM and its nearest offshore area [Sheremet et al., 2016a, b]. Thus, the westernmost part of the Eastern CM is characterized by the NW-oriented compres­ sion, while its eastern part is characterized by NNW-SSE direction of the shortening. Two stages of the shortening during the Cenozo­ ic were defined based on the major Middle Eocene unconformity: the age-frames of the earliest compression stage is defined as the Paleocene—Middle Eocene time, whereas the youngest compression is suggested in the Oli- gocene—Middle Pliocene. Reverse regime. For the majority of sites in the CM we obtained the large display of reverse regimes with trending N-S, NNW- SSE and NW-SE. According to orientation of the thrust front defined offshore, the NW-SE orientation of the Oj compressional axis pre­ vails in the CM during the formation of the main compressional structures. It also has a point for the NE-SW oriented structures of the southwestern part of the Kerch Peninsula (KP). In the area of Sudak the N-S shortening was defined. This N-S and NNE-SSW trend of Teo(pii3imecKiiü xypnoA Ns 4, T. 39, 2017 107 INTERNATIONAL RESEARCH GROUP PROJECT shortening can be traced in KP where the cor­ responding structures overthrust those, which were formed under the NW-SE compression. Moreover, the reverse regimes with Oj trend­ ing NNE-SSW characterize the structures of the Western CM. Thus, the first compression, which follows the Cretaceous extension stage, was the one of, mainly, NW-SE orientation. Strike-slip regime. The analysis of the structural patterns in the Eastern CM re­ veals several faults of NE-SW and NNE-SSW trends with left-lateral strike-slip movements along them. These strike-slip faults cut sev­ eral thrusts and displaced laterally the thrust front in several places. In other cases, there is a right-lateral displacement along NW-SE strike-slip faults. These strike-slip faults also expressed in the youngest deposits of the Miocene-Pliocene age. For the westernmost part of CM the strike- slip regimes with NE-SW orientation of CTj axis were obtained. We consider their relation with the activity along the W estern Crimea dex- tral strike-slip fault. This is confirmed by focal mechanisms of the earthquakes occurred at recent tectonic stage in the Western Crimean Seismic Zone [Gobarenko et al., 2016]. A strike-slip regime with N-S orientation of the ctj axis was also detected in the east­ ernmost part of the Eastern CM. We relate some NNE-SSW-oriented left-lateral strike- slip faults during the Miocene-Pliocene, in agreem ent with [Saintot et al., 1999], to the latest transtensional regime with E-W orien­ tation of ct3 axis. Thus, the N-S trend of the compression characterizes the youngest tec­ tonic stage of the CM evolution resulting in a numerous strike-slip faults in the Eastern CM and folding of E-W trend in KP. Normal regime. A large variety of data re­ lated to the normal faulting type regimes were obtained in the CM. Based on the structural analysis and field observations two types of normal regimes have been defined in the area. 1. Extensional deformations in regards to the rifting stage of the BS during the Cre­ taceous. These normal faults, containing the relict slickensides, tectonic breccias and trac­ es of attached marine organisms, confine the Early Cretaceous depressions within the CM. The corresponding stress fields are character­ ized by N-S and NNE-SSW trend of the a 3 extensional axis in the W estern Crimea and by the NE-SW orientation of the ct3 axis in the Eastern CM. New stratigraphy dating and structural analysis in the W estern CM indi­ cate a later extensional stage for the W estern BS (Valanginian-Barremian) [Murovskaya et al., 2014] than for its Eastern part when the latter experienced the loading of the GC ba­ sin since the Middle Jurassic. 2. The second type of extensional deforma­ tions corresponds to the NW-SE orientation of ct3 axis perpendicular to the NE strike of the compressional structures, which is mani­ fested in the main scarp of the slope offshore the Eastern CM. We relate it with a gravita­ tional effect (sliding) that occurred during the uplifting of the Crimea due to the short­ ening, thus, some structures, formed under the compression, underwent the extension. It also finds the support in the orientation of the Eocene extensional syndepositional faults. Possibly, they relate with the formation of the piggy back basin on top of the highest allochtonous unit northwards. Recent regime. Along the northern margin of the BS (the Crimea-Caucasus coast), the main structures of shortening are marked by an active Crimea Seismic Zone (CSZ). The analyses of the focal mechanisms of 31 strong earthquakes during 1927—2013 reveals the recent transpression regime in the western part of the CSZ whereas in its eastern part, according to seismicity, gravity field, modes of deformation and the velocity model, it is possible to suggest the present day compres­ sional regime. The latter demonstrates: 1) the reactivation of basem ent faults that, accord­ ing to [Sydorenko et al., 2016], related to the formation of the Triassic basin, and 2) indi­ cates the underthusting of the East BS highly extended crust under the Scythian Plate con­ tinental crust. 108 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES References Gobarenko V. S., Murovskaya A. V, Yegorova T. P, She- remet Y., 2016. Collisional processes at the northern margin of the Black Sea. Geotectonics 50(4), 07—24. doi: 10.1134/S0016852116040026. Murovskaya A., Hippolite J.-C., Sheremet Ye., Yegoro­ va T, Volfman Yu., Kolesnikova Ye., 2014. Deforma­ tion structures and stress field of the south-western Crimeain the context of the evolution of western Black Sea Basin. Geodinamika (2), 53—68 (in Rus­ sian). Saintot A., Angelier J., Chorowicz J., 1999. Mechani­ cal significance of structural patterns identified by remote sensing studies: a multiscale analysis of tectonic structures in Crimea. Tectonophysics 313, 187—218. doi: 10.1016/S0040-1951(99)00196-1. Sheremet Y, Sosson M., Müller C., Murovskaya A., Gin- tov O., Yegorova T, 2016a. Key problems of stra­ tigraphy in the Eastern Crimea Peninsula: some insights from new dating and structural data. In: M. Sosson, R. Stephenson, Sh. Adamia (Eds.). Tec­ tonic Evolution of the Eastern Black Sea and Cauca­ sus. Geol. Soc. London Spec. Publ., 428. http://doi. org/10.1144/SP428.14. Sheremet Y., Sosson M., Ratzov G., Sidorenko G., Ye­ gorova T., Gintov O., Murovskaya A. V., 2016b. An offshore-onland transect across the north-east­ ern Black Sea basin (Crimean margin): evidence of Paleocene to Pliocene two-stage compres­ sion. Tectonophysics 688, 84—100. doi: 10.1016/j. tecto.2016.09.015. Sydorenko G., Stephenson R., Yegorova T., Starosten- ko V., Tolkunov A., Janik T., Majdanski M., Voit- sitskiy Z., Rusakov O., Omelchenko V., 2016. Geo­ logical structure of the northern part of the Eastern Black Sea from regional seismic reflection data in­ cluding the DOBRE-2 CDP profile. Geol. Soc. Lon­ don, Spec. Publ. 428. doi: 10.1144/SP428.15. Paleo- and recent stress regimes of the Crimea Mountains based on micro- and macroscale tectonic analysis and earthquakes focal mechanisms © A . M urovskaya1, Ye. Sheremet2, M. Sosson2, O. Gintov1, T. Yegorova1, 2017 in s titu te of Geophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine 2Universite Cote d'Azur, UMR Geoazur, CNRS, Sophia Antipolis, France The Crimea M ountains (CM) belongs to the northern branch of the Alpine Belt. Being the northwestern continuation of the Great­ er Caucasus (GC) and a part of the inverted northern margin of the Black Sea (BS), the CM region shows the similarities in structural development of both the domains, implying the common tectonic evolution of the GC — Eastern BS area. In the current study, we focus on the Meso- Cenozoic time-span of tectonic evolution of the CM and the adjacent BS margin in order to define paleo- and recent stress regimes alternated during its tectonic history, based on the recent geological field observations, the results of structural analysis, the micro- tectonic data and the analysis of focal mecha­ nisms of the earthquakes. Thus, the main pur­ pose of our study is to find and investigate the correlation between the stress field and the large-scale deformation structures with subsequent determination of major tectonic events. The Cenozoic compression. The major direction of the shortening during the Ce­ nozoic was defined in regards of main ori­ entation (trends) of the thrusts and fold axis developed in the Eastern CM and its nearest offshore area [Sheremet et al., 2016a, b]. Thus, the westernmost part of the Eastern CM is characterized by the NW-oriented compres­ sion, while its eastern part is characterized by NNW-SSE direction of the shortening. Two stages of the shortening during the Cenozo- Teo(pu3unecKuü xypnoA Ns 4, T. 39, 2017 109 http://doi INTERNATIONAL RESEARCH GROUP PROJECT ic were defined based on the major Middle Eocene unconformity: the age-frames of the earliest compression stage is defined as the Paleocene—Middle Eocene time, whereas the youngest compression is suggested in the Oli- gocene—Middle Pliocene. Reverse regime. For the majority of sites in the CM we obtained the large display of reverse regimes with Oj trending N-S, NNW- SSE and NW-SE. According to orientation of the thrust front defined offshore, the NW-SE orientation of the CTj compressional axis pre­ vails in the CM during the formation of the main compressional structures. It also has a point for the NE-SW oriented structures of the southwestern part of the Kerch Peninsula (KP). In the area of Sudak the N-S shortening was defined. This N-S and NNE-SSW trend of shortening can be traced in KP where the cor­ responding structures overthrust those, which were formed under the NW-SE compression. Moreover, the reverse regimes with Oj trend­ ing NNE-SSW characterize the structures of the Western CM. Thus, the first compression, which follows the Cretaceous extension stage, was the one of, mainly, NW-SE orientation. Strike-slip regime. The analysis of the structural patterns in the Eastern CM re­ veals several faults of NE-SW and NNE-SSW trends with left-lateral strike-slip movements along them. These strike-slip faults cut sev­ eral thrusts and displaced laterally the thrust front in several places. In other cases, there is a right-lateral displacement along NW-SE strike-slip faults. These strike-slip faults also expressed in the youngest deposits of the Miocene-Pliocene age. For the westernmost part of CM the strike- slip regimes with NE-SW orientation of Oj axis were obtained. We consider their relation with the activity along the W estern Crimea dextral strike-slip fault. This is confirmed by focal mechanisms of the earthguakes oc­ curred at recent tectonic stage in the W est­ ern Crimean Seismic Zone [Gobarenko et al., 2016]. A strike-slip regime with N-S orientation of the <7j axis was also detected in the east­ ernmost part of the Eastern CM. We relate some NNE-SSW-oriented left-lateral strike- slip faults during the Miocene-Pliocene, in agreem ent with [Saintot et al., 1999], to the latest transtensional regime with E-W orien­ tation of ct3 axis. Thus, the N-S trend of the compression characterizes the youngest tec­ tonic stage of the CM evolution resulting in a numerous strike-slip faults in the Eastern CM and folding of E-W trend in KP. Normal regime. A large variety of data re­ lated to the normal faulting type regimes were obtained in the CM. Based on the structural analysis and field observations two types of normal regimes have been defined in the area. 1. Extensional deformations in regards to the rifting stage of the BS during the Cre­ taceous. These normal faults, containing the relict slickensides, tectonic breccias and trac­ es of attached marine organisms, confine the Early Cretaceous depressions within the CM. The corresponding stress fields are character­ ized by N-S and NNE-SSW trend of the cr3 extensional axis in the W estern Crimea and by the NE-SW orientation of the o3 axis in the Eastern CM. New stratigraphy dating and structural analysis in the W estern CM indi­ cate a later extensional stage for the W estern BS (Valanginian-Barremian) [Murovskaya et al., 2014] than for its Eastern part when the latter experienced the loading of the GC ba­ sin since the Middle Jurassic. 2. The second type of extensional deforma­ tions corresponds to the NW-SE orientation of ct3 axis perpendicular to the NE strike of the compressional structures, which is mani­ fested in the main scarp of the slope offshore the Eastern CM. We relate it with a gravita­ tional effect (sliding) that occurred during the uplifting of the Crimea due to the short­ ening, thus, some structures, formed under the compression, underwent the extension. It also finds the support in the orientation of the Eocene extensional syndepositional faults. Possibly, they relate with the formation of the piggy back basin on top of the highest allochtonous unit northwards. Recent regime. Along the northern margin of the BS (the Crimea-Caucasus coast), the main structures of shortening are marked by an active Crimea Seismic Zone (CSZ). The n o Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES analyses of the focal mechanisms of 31 strong earthquakes during 1927—2013 reveals the recent transpression regime in the western part of the CSZ whereas in its eastern part, according to seismicity, gravity field, modes of deformation and the velocity model, it is possible to suggest the present day compres- References Gobarenko V. S„ Murovskaya A. V, Yegorova T. P, She- remet Y., 2016. Collisional processes at the northern margin of the Black Sea. Geotectonics 50(4), 07—24. doi: 10.1134/S0016852116040026. Murovskaya A., Hippolite J.-C., Sheremet Ye., Yegoro­ va T, Volfman Yu., Kolesnikova Ye., 2014. Deforma­ tion structures and stress field of the south-western Crimeain the context of the evolution of western Black Sea Basin. Geodinamika (2), 53—68 (in Rus­ sian). Saintot A., Angelier J., Chorowicz J., 1999. Mechanical significance of structural patterns identified by re­ mote sensing studies: a multiscale analysis of tectonic structures in Crimea. Tectonophysics 313,187—218. doi: 10.1016/S0040-1951(99)00196-1. Sheremet Y, Sosson M., Müller C., Murovskaya A., Gin- tovO., Yegorova T, 2016a. Key problems of stratigra­ phy in the Eastern Crimea Peninsula: some insights sional regime. The latter demonstrates: 1) the reactivation of basem ent faults that, accord­ ing to [Sydorenko et al., 2016], related to the formation of the Triassic basin, and 2) indi­ cates the underthusting of the East BS highly extended crust under the Scythian Plate con­ tinental crust. from new dating and structural data. In: M. Sosson, R. Stephenson, Sh. Adamia (Eds.). Tectonic Evolu­ tion of the Eastern Black Sea and Caucasus. Geol. Soc. London Spec. Publ., 428. http://doi.org/10.1144/ SP428.14. Sheremet Y, Sosson M., Ratzov G., Sidorenko G., Yego­ rova T, Gintov O., Murovskaya A. V., 2016b. An off- shore-onland transect across the north-eastern Black Sea basin (Crimean margin): evidence of Paleocene to Pliocene two-stage compression. Tectonophy­ sics 688, 84—100. doi: 10.1016/j.tecto.2016.09.015. Sydorenko G., Stephenson R„ Yegorova T, Starostenko V, Tolkunov A., Janik T, Majdanski M„ Voitsitskiy Z„ RusakovO., Omelchenko V., 2016. Geological struc­ ture of the northern part of the Eastern Black Sea from regional seismic reflection data including the DOBRE-2 CDP profile. Geol. Soc. London, Spec. Publ. 428. doi: 10.1144/SP428.15. Magmatism and ore formation on the example of Upper Cretaceous Bertakari and Bneli Khevi Ore deposits, Bolnisi ore district, Georgia © N. Sadradze1, Sh. Adam ia1, T. Beridze2, T. Gavtadze2, R. M igineishvili2, 2017 1Tbilisi State University, M. Nodia Institute of Geophysics, Tbilisi, Georgia 2Tbilisi State University, A. Janelidze Institute of Geology, Tbilisi, Georgia Magmatic evolution is an important event in the formation and development of the geo­ logical structure of Southern Georgia, where several reliably dated volcanogenic and volcanogenic-sedimentary formations are established. The region represents a m odem analogue of continental collision zone, where subduction-related volcanic activity lasted from Paleozoic to the end of Paleogene. After the period of dormancy in the Early-Middle Miocene, starting from the Late Miocene and up to the end of the Pleistocene, syn-postcol- lisional primarily subaerial volcanic eruptions followed by formation of volcanic highlands and plateaus occurred in the region. The Artvin-Bolnisi unit forms the north­ western part of the Lesser Caucasus and represents an island arc domain of so-called the Somkheto-Karabakh Island Arc or Bai- burt-Garabagh-Kapan belt. It was formed mainly during the Jurassic-Eocene time in­ terval on the southern margin of the Eurasian plate by north-dipping subduction of the Neotethys Ocean and subsequent collision Teo(pu3unecKuü xypnoA Ns 4, T. 39, 2017 111 http://doi.org/10.1144/ INTERNATIONAL RESEARCH GROUP PROJECT Ma 72,1 Age Formation Thickness Tetritscaro 200-300 m K2t Shorsholeti 150-350 m K2sh Gasandami 150-600 m K2gs Lithology \ A l \ A A A A A A A A A A A A A A A A V V V V V V V V V V V V V V V V V V V ?î A • A • A . A . A • A - A • A • A A A V V V V A A A. A. A A A A A A • A • A • A • A . A ■ A • A - A V V V V A A A A A A A A A A • A • A • A • A • A ■ A • A - A / A A A V \ A A A A A A A A A A • A • A A ■ A ■ A • A • A • A A A A A A A A A A A A A A A A A A A v v v v v v v v v v v v v v v v v v v Description Limestones, maris, interlayers of epiclastic deposits Extrusive, coarse-grained, medium-grained and fine-grained volcanoclastic rocks of calc-alkanne and sub-alkaline andesite- basaltic composition; interlayers of limestones, marls and epiclastic deposits Extrusive, coarse-grained, medium-grained and fine-qrained volcanoclastic rocks of calc-alkaltne dacite-rhyolitic composition; interlayers of limestones, marls and epiclastic deposits 89,8 100,5 A A A A A A A A A A A A A A A A A A v v v v v v v v v v v v v v v v v v v c .2'30aVÎ/5 T a n d z i a K2tn 150-700 m Mashavera K2ms 250-1000 m Didgverdi K2dg 250-750 m A A A À A A A A A A A Â A A A A A A v v v v v v v v v v v v v v v v v v - ► . . . . . . . A A A A A A A A A . A A A A A A A . A A v v v v v v v v v v v v v v v v v v v l U U U U U i i i n A U A A A A A A A A A A A A A A A A A A V V V V V V V V V V V V V V V V V V V i i m u i A U i i i i U i i A A A A A A A A A A A A A A A A A V V V V V V V V V V V V V V V V V V Extrusive, coarse-grained, medium-grained and fine-grained volcanoclastic rocks of calc-alkaline andesite-basaltic composition^ rare interlayers of limestones, marls and epiclastic deposits Extrusive, coarse-grained, medium-grained and fine-grained volcanoclastic rocks of calc-alkanne dacite-rhyolitic composition; interlayers of carbonate and epiclastic deposits Extrusive, coarse-grained and fine-grained volcanoclastic rocks of andesite-basaltic composition; interlayers of limestones, marls and epiclastic deposits Extrusive, medium-grained and fine-grained volcanoclastic rocks of dacite-rhyolitic composition; interlayers of limestones and epiclastic deposits Conglomerates, gritstones, sandstones, limestones and fine-grained volcanoclastic rocks Fig. 1. Lithostratigraphic column of the Upper Cretaceous deposits of the Bolnisi ore district, modified by [Adamia etal., 2016]. of the Anatolia-Iranian continental plate. The Artvin-Bolnisi tectonic unit, includ­ ing the Bolnisi ore district, was developing as a relatively uplifted island-arc type unit with suprasubduction magmatic events. Vol- canogenic complexes are characterized by variable lateral and vertical regional strati­ graphic relationships and are subdivided into several formations due to their composition. Volcanics are attributed to calc-alkaline-sub- alkaline series. Depositional environment of the Upper Cretaceous volcanic formations varies from shallow-marine to subaerial set­ tings. Mafic to intermediate volcanic rocks 112 reo<pU3WiecKUÜ xcypHOA N* 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES Fig. 2. Types of hydrothermal breccias: a — hydrothermal breccia, Bneli Khevi outcrop; b — pseudobreccia, Bneli Khevi outcrop; c — hydrothermal breccia, Bertakari, Kldovani Ubani, core image BK 822,228—231 m; d — pseu­ dobreccia, Bertakari, Kldovani Ubani, core image BK 875,260—263 m. are in subordinate amount. Felsic formations (Mashavera and Gasandami) are the major hosts of numerous ore deposits (Madneuli, Sakdrisi, Bertakari, Bneli Khevi etc.) within the ore field (Fig. 1). The common consent of the researchers exists about the genetic link of the Bolnisi ore field gold-polymetallic ore-forming proces­ ses with the late Cretaceous suprasubduc- tion magmatism. The latter is related to the north-dipping subduction zone of the Lesser Caucasus which conditioned island-arc type volcanic activity and mineralization of the late Cretaceous Tethys and its northern ac­ tive margin. Campanian nannoplankton fossils have been discovered in hydrothermally slightly altered rocks (pelitic tuffs, tuff-argillites, tuff- sandstones) of Bertakari area. The peculiarities of magmatic activity and geodynamic development of the region stipulated synchronous formation of signifi­ cant base and precious metals deposits of the Bolnisi ore district. W ithin the Bolnisi ore district, Bertakari and Bneli Khevi deposits host lithofacies and spatial distribution of associated mineraliza­ tion that has been studied. The outcrops and drill cores visual observations as well as thin section microscopy has revealed the link of the mineralization to various types of breccias Геофизический журнал Ns 4, T. 39,2017 (phreatic, phreatomagmatic and hydrother­ mal) within Bertakari and Bneli Khevi. It is noteworthy the recognition of hydro- thermal breccias with jigsaw-fit clast textures (Fig. 2, a, b) and pseudobreccias (Fig. 2, c, d) in the m entioned above deposits [Gelashvili et al., 2015; Lavoie, 2015]. Pseudobreccias are resulted from diffusive/selective alteration of intrusive, subvolcanic or volcaniclastic rocks. Development of jigsaw-fit clast textures in breccias is induced by hydraulic brecciation [Casetal.,2011]. The deposits are hosted by Gasandami for­ mation that is represented by following lithofac- es types: felsic volcanic lapilli tuffs, ignimbrites, pumice tuffs and reccias and rhyodacitic dome. The existence of epigenetic hydrothermal breccia bodies is the common feature of ma­ ny geodynamic setting types, especially of island-arcs, and is the substantial part of the long-lasting history of magmatic-hydrother­ mal activity [Howard et al., 2015]. Acknowledgements. This work was suppor­ ted by Rustaveli National Science Foundation (SRNSF), projects № 04-45 (GDRI — Interna­ tional Research Group: South Caucasus Geo- Science (Georgia — Eastern Black Sea)) and YS-2016-14 (Late Mezosoic — Ealy Cenozoic Suprasubduction Magmatism Evolution and Geodynamics: Constraints from Southern Georgia). 113 INTERNATIONAL RESEARCH GROUP PROJECT References Adamia S., Moritz R., Shubitidze J., Natsvlishvili M., Tchokhonelidze M., 2015. Epithermal and porphyry deposits of the Lessser Caucasus (Georgia and Ar­ menia). Unpublished fieldguide book for the 13th SGA Biennial meeting, Nancy, 53 p. Cas R., Giordano G., Balsamo E, Esposito A., Lo Mastro S., 2011. Hydrothermal Breccia Textures and Processes: Lisca Bianca Islet, Panarea Vol­ cano, Aeolian Islands, Italy. 2011. Economic Geol­ ogy 106(3), 437—450. http://dx.doi.org/10.2113/ econgeo. 106.3.437. Gelashvili N„ Tsertsvadze B„ Kvantaliani G„ Gelas- hvili A., 2015. The first information about gold- polymetallic ore composition material in Bektakari deposit. Bolnisi ore district: Proc. of Sci. Conf. on Recent Geological Problems of Georgia, publisher «Technical University», 23—24 April, 2015. P. 35—39 (in Georgian). Howard N., Andrew F., Brookes D., 2015. Genetic clas­ sification of breccias, http://www.academia.edu/ 9593848/GENETIC_CLASSIFICATION_OF_BREC- CIAS. Lavoie J., 2015. Genetic constraints of the Late-Creta- ceous Epithermal Beqtakari prospect, Bolnisi Min­ ing District, Lesser Caucasus, Georgia. University of Geneva, Department of Earth Sciences, Master of Geology Thesis, P. 1—82. Paleogene sedimentary development and tectonic conditions of shagap piggyback basin (Armenia) © L. Sahakyan1, M. Sosson2, A. Avagyan1, D. Bosch3, T. Grigoryan1, S. Vardanyan1, O. Bruguiei3, 2017 in s titu te of Geological Sciences, National Academy of Sciences of Republic of Armenia, Yerevan, Armenia 2Université Côte d'Azur, UMR Géoazur, CNRS, Sophia Antipolis, France 3 Université de M ontpellier II, UMR Géosciences, CNRS, Montpellier, France Shagap syncline is elongated asymmetric basin presented by Paleogene deposition of about 1.5 km thicknesses. Sedimentation took place after collision of Eurasian plate and South Armenian M icrocontinent (SAM). In Middle Eocene—Oligocene time piggyback basin by slope deposition and turbidite accu­ mulation, controlled by gravitational process­ es, was formed. Lithologically different type of deposition in this partly isolated basin is the result of constant input of terrigenous ma­ terial, volcanism and palaeoclimate changes. Discocyclina-Nummulitic limestones (packstone/grainstone) without micrite and cement evidence shallow marine slope en­ vironment where regular flow was available. Nummulite and red algae (Lithothamnion) limestones show relatively low light sea en­ vironment {oligophotic zone). Coralline built with nummulitides were formed in-situ indi­ cating accumulation in a shallow condition with intense light (photic zone). Trachyandesite dikes and sills (ALIO-14 — N 39° 57.296', E 44° 51.195') were injected into Lower Paleocene—Lower and Middle Eocene sedimentary rocks. Shoshonite series trachyandesites nor­ malised by chondrites have mobile elements enrichment (Rb, Ba and Th) with negative HFSE (Nb, Ta) anomalies. The (La/Sm)CN ratio yield 6.84 value but the (La/Yb)^ ratio is 38.17, suggesting the presence of residual material from the deep magmatic source. Neodymium and strontium isotopes yield low eNd(14 5Mâ and high 87Sr/86Sr(-14 5Mâ ratios, respectively -0.4 and 0.7054. Initial Pb/Pb isotopic ratios yield 207Pb/204Pb(i) — 15,67; 208Pb/204Pb(i) — 39.05, suggesting EM2, slab-component con­ tribution and crustal contamination. The obtained U-Pb zircon age for trachy­ andesites is 14.5+0.2 Ma, which is coincident with magmatism reactivation in the Middle- Upper Miocene, after Arabian-Eurasian plates collision in the Upper Eocene-Oligocene. 114 Геофизический журнал Ne 4, T. 39, 2017 http://dx.doi.org/10.2113/ http://www.academia.edu/ SOUTH CAUCASUS GEOSCIENCES Tectonic evolution of the Crimean Mountains since the Triassic: Insight from the new dating and on-and-offshore structural data (macro- and microscale), In general tectonic context of the Greater Caucasus-Black Sea domain © Ye. Sherem et1, M. Sosson1, A. M urovskaya2, O. Gintov2, T. Yegorovai2, 2017 ^n iv ers ite Cote d'Azur, UMR Geoazur, CNRS, Sophia Antipolis, France in s titu te of Geophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine The Crimea, being a part of the Black Sea-Greater Caucasus system (BS-GC), owes its origin to the subduction of the Neotethys beneath the Eurasian margin which is the main geodynamical process that had a significant influence on the de­ velopment of the Crimea and changed the tectonic conditions during its geological history. Two main tectonic stages were record­ ed in BS-GC region concerning the sub­ duction of the Neotethys and its closure: 1) the opening of the BS and the GC ba­ sins in a back-arc position, starting from the Early-Middle Jurassic and then after during the Early to mid-Cretaceous and in the Paleocene-Eocene times; 2) the con­ tinental collision between the Eurasian margin with the Taurides-Anatolides and the South Armenian Microplate (TASAM) and then with Arabian plate. This colli­ sion triggered the shortening of the BS Basins, thus, the inversion structures have been described all around the Black Sea (Pontides-Balkanides orogens, Romanian shelf and the area of Odessa Shelf— Crimea—Greater Caucasus). The presence of two flysch units of dif­ ferent ages (Tauric Gp and Cretaceous ba­ sin deposits) that are outcropping in the CM reveals a period of subsidence. That allows the conclusion about the formation of the Triassic Trough (Basin) within the southern margin of Laurasia in the fore/ back-arc position. The normal faults in the basement which have been formed during this period in consequence will be reacti­ vated during the following BS rifting stage and the Cenozoic shortening [Sydorenko etal., 2016[). The enigmatic Cimmerian deforma­ tions, in addition to other well-known stated versions, one can suggest a slab shallowing during the Early Jurassic that could result in compression (accretion) of basin sediments. The extensional stage, in the Crimea region, was followed by the development of the GC back-arc Basin in the Early- Middle Jurassic and capped by back-arc magmatism of the Middle Jurassic related to the subduction (40Ar/39Ar dating and the geochemical analysis of magmatic rocks, according to [Meijers et al., 2010]) in both future mountain systems. The Jurassic period is characterized by wide distribution of massive carbonated platforms and reef limestones on top of the deformed basinal deposits of the Triassic- Middle Jurassic age (the carbonate build­ up are known in the GC, and evidential from the seismic data on the Shatskiy Ridge). These carbonated facies, much of them are platform, continued through the Teo(pii3imecKiiu xcypHOA Ns 4, T. 39, 2017 115 INTERNATIONAL RESEARCH GROUP PROJECT entire Late Jurassic-Berriasian time span (till the Hauterivian) in the central CM. The olistoliths origin of large carbonated Plateaus in the Crimea is not confirmed during the field observations. During the Early Cretaceous the BS basin (a back-arc basin, north of the subduction zone of Neotethys beneath Eurasia) was initiated by rifting and then, a probable spreading center produced the oceanization of this basin [Sosson et al., 2016]. Subduction of the spreading center of the north branch of Neotethys formed an asthenospheric window. It could produce heating and, as the result, the weakening of the strong lithosphere of Eurasia. This process should initiate the rifting of the Eastern BS during the Early Cretaceous, and then, as mentioned by [Stephenson, Schellart, 2010]), the roll back of the slab should favor the opening of this small oceanic basin probably dur­ ing the time limit between Early and Late Cretaceous. The inversion of the North Eastern BS margin is also the result of the evolu­ tion of the Neotethys subduction zone. During the Latest Cretaceous—Middle Eocene period (74—40 Ma), collision be­ tween a continental microplate (TASAM) with the Eurasia initiated in the Lesser Caucasus and then continued westward during the Eocene. The inversion of the CM commenced during the Paleocene [Sheremet et al., 2016a, b]. Thus, we suggest that the collisional process to the south of the Eastern BS initiated the compression in the CM by reactivation of the Late Triassic-Early Jurassic normal faults in the basement. Then, after a pe- References Gobarenko V S., Murovskaya A. V., Yegorova T. P., Sheremet Y., 2016. Collisional processes at the north­ ern margin of the Black Sea. Geotectonics 50(4), 07—24. doi: 10.1134/S0016852116040026. riod of a low rate compression (Middle Eocene), the inversion since the Latest Eocene has been renewed. Probably, this second period of shortening in the Crimea could be explained by initial col­ lision of the Arabian plate with Eurasia since they coincide in time. The very ex­ tended (sub-oceanic) crust, created dur­ ing the Cretaceous by the latest period of shortening (latest Eocene-Miocene time span) have been already cold enough and, therefore, mechanically stronger in or­ der to affect the continental margins and produce the compressional deformations. The Shatskiy Ridge plays as indenter in the underthrusting of the Eastern BC mar­ gin. Thus, the CM have been occurred as a result of a thin skin tectonic offshore and both thick- and thin-skin tectonic on land [Sheremet et al., 2016a]. In the Latest Miocene the Messinian sea level drop, recorded in the significant erosion surface offshore, against the back­ ground of continuing shortening, most likely triggered the mud volcano activity that at present is the distinctive feature of the BS topography. The current stage of the CM is char­ acterized by the seismicity of magnitude 4—6 located in lower crust and upper mantle at depth between 30 and 38 km showing, mainly a north dipping plan of its distribution in the Eastern CM [Gobarenko et al., 2016]. The reverse faults in the basement, as well as strike slip faults, reactivated by the inversion of the BS (Alushta-Simferopol fault, Western Crimea dextral strike-slip fault), should be responsible for the main seismic activ­ ity in Crimea. Meijers M. J. M., Vrouwe B., Van Hinsbergen D. J. J., Kuiper K. F., Wijbrans J., Davies G. R., Stephenson R. A., Kaymakci N., Matenco L., Saintot A., 2010. Jurassic arc volcanism on Crimea (Ukraine): impli­ 116 Teo(pu3imecKiiü. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES cations for the paleo-subduction zone configuration of the Black Sea region. Lithos 119(3), 412—426. doi: 10.1016/j.lithos.2010.07.017. Sheremet Y, Sosson M., Müller C., MurovskayaA., Gin- tovO., Yegorova T, 2016a. Key problems of stratigra­ phy in the Eastern Crimea Peninsula: some insights from new dating and structural data. In: M. Sosson, R. Stephenson, Sh. Adamia (Eds.). Tectonic Evolution of the Eastern Black Sea and Caucasus. Geol. Soc. London Spec. Publ., 428. http://doi.org/10.1144/ SP428.14. Sheremet Y, Sosson M., Ratzov G., Sidorenko G., Yego­ rova T, GintovO., MurovskayaA. V, 2016b. An off- shore-onland transect across the north-eastern Black Sea basin (Crimean margin): evidence of Paleocene to Pliocene two-stage compression. Tectonophysics 688, 84— 100. doi: 10.1016/j.tecto.2016.09.015. Sosson M., Stephenson R., Sheremet Y, Rolland Y, Adamia S., Melkonian R., Kangarli T, Yegorova T, Avagyan A., Galoyan G., Danelian T, Hassig M., Müller C., Sahakyan L., Sadradze L., Sadradze N., Alania V, Enukidze O., MosarJ., 2016. The eastern Black Sea-Caucasus region during the Cretaceous: New evidence to constrain its tectonic evolution. C. R. Geosci. 348, 23—32. http://dx.doi.Org/10.1016/j. crte.2015.11.002. Stephenson R., Schellart W. P., 2010. The Black Sea back- arc basin: insights to its origin from geodynamic models of modem analogues. Geol. Soc. London Spec. Publ. 340(1), 11—21. Sydorenko G., Stephenson R., Yegorova T, Starostenko V, Tolkunov A., Janik T, Majdanski M., Voitsitskiy Z., Rusakov O., Omelchenko V., 2016. Geological struc­ ture of the northern part of the Eastern Black Sea from regional seismic reflection data including the DOBRE-2 CDP profile. Geol. Soc. London Spec. Publ. 428, doi: 10.1144/SP428.15. The highlights and the contribution of International Research Group (IRG) «South Caucasus Geosciences» (France, Armenia, Azerbaijan, Georgia and Ukraine) © M. Sosson1, S. Adamia2, T. Kangarli3, A. Karakanian4, V. Starostenko5, T. Danelian6, J. E R itz7, 2017 U niversité Côte d'Azur, UMR Géoazur, CNRS, Sophia Antipolis, France 2Javakhishvili Tbilisi State University, Tbilisi, Georgia in s titu te of Geology and Geophysics, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan in s titu te of Geological Sciences, National Academy of Sciences of Republic of Armenia, Yerevan, Armenia in s titu te of Geophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine 6Université de Lille, CNRS, UMR Evo-Eco-Paleo, Lille, France 7 Université de M ontpellier II, UMR Géosciences, CNRS, Montpellier, France Initiated in collaboration within the frame­ work of proj ects funded by the European prog­ rammes INTAS, Erasmus Mundus and PICs, LLA programmes of the CNRS/INSU, three French laboratories (Geosciences of M ont­ pellier, Geoazur of Nice Sophia Antipolis and Evo-Eco-Paleo of Lille), and Institutes of Aca­ demies of Sciences and Universities of Armenia, Azerbaijan, Georgia an International Research Group (IRG: GDRI de CNRS/INSU) «South Caucasus Geosciences» were founded in 2010. Ukraine, presented by Institute of Geophysics of the Academy of Science of Ukraine, became one of the partners of IRG in 2014. W ith a support of Middle East Basins Evolution and DARIUS programmes (con­ sortium of oil companies, Univ. Pierre et Marie Curie Paris VI, and CNRS/INSU) this IRG aimed at solving the Earth Sciences questions, mainly in resources and hazard fields, in the Caucasus-Eastern Black Sea Domain (CEBSD) that has a high potential in research since this part of the Alpine belt evolved during the long-lived subduction of Геофизический журнал Ns 4, T. 39, 2017 117 http://doi.org/10.1144/ http://dx.doi.Org/10.1016/j INTERNATIONAL RESEARCH GROUP PROJECT the Neotethys ocean due to its closure (see for a review e.g. [Sosson et al.r 2010, 2016]). The main issues to solve in the eastern Black Sea and Caucasus realm in this geo­ dynamic context are: 1) the time-space evo­ lution of geodynamic processes (subduction, oped in these tectonic settings; 3) the rela­ tion in time and the continuity of structures between the eastern Black Sea, the Greater Caucasus, the Lesser Caucasus and those of the Taurides-Anatolides, Pontides belt and of the NW Iran as well. Scythian Platform Arabian Platform A rabia 45°N 35°N km 300 Eurasia 30ÛE 35ÖE 40°E 45°E 50°E 45ÖN 35°N Crimea-Greater Caucasus mountain belt European margin (Pontides, Somkheto-Karabakh) with magmatic arc Lesser Caucasus units (including! ophiolites) Sakarya accreted terrane Taurides-Anatolides/South Armenian accreted terranes, with ophiolites (olive) Iran accreted terrane (Eo-Cimmerian) Melamorphic massifs Taurides-Anatolides including allochthonous nappes and obducted ophiolites Fig. 1. Tectonic map of the Black Sea-Caucasus domain and surrounding areas, modified from [Sosson et al., 2016,2017], showing the main field locations of IRG studies. obduction, collision) responsible for the clo­ sure of the northern and southern branches of Neotethys; 2) the timing of deformation and the evolution of the back-arc basins devel- An integral part of the project, exchange of scientists, apart from the important role of joint research, favored to the development of its international level, giving the birth to a 118 reo<pU3WiecKUÜ xcypHOA N* 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES new generation of scientists able to provide the research in the good tradition of French (European) geological school (Masters, PhDs, postdocs). A significant part of these valuable re­ sults constitute: two volumes of Special Publications of the Geological Society of London (Vol. 340 and 428), they have been published in the international and local edi­ tions, as well as presented in Ph.D Thesis. It is a multidisciplinary study covering topics in structural geology/tectonics, passive and active source seismology and seismic profil­ ing, deep Earth's structure (seismic images), geochemistry, palaeontology, petrography, paleomagnetism, geochronology, sedimen- tology and stratigraphy, reporting results ob­ tained during the DARIUS programme and related projects in the eastern Black Sea and Caucasus realm. During 2014—2017 our IRG group worked in the region north of the Eastern Black Sea Basin (Crimea), in the Greater Caucasus (Georgia and Azerbaijan), and in the Lesser Caucasus (Armenia, Azerbaijan and Georgia) aiming to precise the evolution of the Eastern Black Sea-Caucasus realm primarily during the Mesozoic-Cenozoic time span. References Sosson M., Rolland Y, Danelian T, Muller C., Melkonyan R., Adamia S., Kangarli T, Avagyan A., Galoyan G., 2010. Subductions, obduction and col­ lision in the Lesser Caucasus (Armenia Azerbaijan, Georgia), new insights. In: M. Sosson, N. Kaymakci, R. Stephenson, E Bergarat, V. Starostenko (Eds.). Sedimentary Basin Tectonics from the Black Sea and Caucasus to the Arabian Platform. Geol. Soc. London Spec. Publ. 340, 329—352. Sosson M„ Stephenson R., Adamia Sh., 2017. Tectonic Evolution of the Eastern Black Sea and Caucasus: an introduction. In: M. Sosson, R. A. Stephenson, During this time the tectonic setting of the area can be characterized as one of general plate convergence as the Neotethys Ocean (or branches of a Neotethys Ocean system) was subducted and eventually closed. The geo­ logical record is essentially one of sedimen­ tary basins being formed in an extensional back-arc setting and through to the compres- sional deformations (inversion) of these ba­ sins linked to the Neotethys closure and the consequences of the related deformations. The inversion of basins has roughly occurred in two main phases: 1) from Late Cretaceous to Early Eocene linked broadly to the closure of what is referred to as the northern branch of Neotethys, and 2) from Oligocene to recent, linked broadly to the closure of what is re­ ferred to as the southern branch of Neotethys, which corresponds to the eventual suturing of the Arabia with Eurasia. The main directions of our activity within the IRG project: 1) onshore geological studies from Georgia, Azerbaijan, Armenia and Iran; 2) onshore geological studies from the Black Sea margins of Crimea and Turkey as well as geophysical data and other subsurface data from the eastern Black Sea and its northern margin. S. A. Adamia (Eds.) Tectonic Evolution of the Eastern Black Sea and Caucasus. Geol. Soc. London Spec. Publ. 428, https://doi.org/10.1144/SP428.16. Sosson M„ Stephenson R., Sheremet Y, Rolland Y, Adamia Sh., Melkonian R„ Kangarli T, Yegorova T, Avagyan A., Galoyan Gh„ Danelian T, Hässig M„ Meijers M., Müller C„ Sahakyan L , Sadradze N., Alania V, Enukidze O., MosarJ., 2016. The Eastern Black Sea—Caucasus region during Cretaceous: new evidence to constrain its tectonic evolution. Comptes Rendu Géoscience 348,23—32. https://doi. org/10. 1016/j.crte.2015.11.002. Геофизический журнал Ns 4, T. 39, 2017 119 https://doi.org/10.1144/SP428.16 https://doi INTERNATIONAL RESEARCH GROUP PROJECT Deep crustal structure of the transition zone of the Scythian Plate and the East European Platform (DOBRE-5 profile): consequences of the Alpine Tectonic evolution ©V. S tarostenko1, M. Sosson 2, L. F arfulyak1, O. G in tov1, T. Yegorova 1, A M urovskaya 1, Ye. Sherem et2, O. Legostaeva 1, 2017 in s titu te of Geophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine 2Université Côte d'Azur, UMR Géoazur, CNRS, Sophia Antipolis, France In 2011 an international team carried out the DOBRE-5 WARR (wide-angle reflection and refraction) seismic profile [Starostenko et al., 2015]. Its major part runs in the W-E direction through the Scythian Plate in the northwestern shelf of the Black Sea (BS) and the plain Crimea. The velocity section on the profile indicates a seismic boundary inclined eastwards with a low angle. The boundary is traced at the depth of ~2 km near the Zmeinyj Island then it goes below the northwestern shelf (Karkinit Trough) and beneath the plain Crimea, and plunges to a depth of 47 km at the transition to the Kerch Peninsula. This zone is interpreted as a transition zone (TZ) between the Eastern European platform (EEP) and the SP, naimely on the seismic profile we the projection of this zone [Starostenko et al., 2015] . A geodynamic interpretation of this tec­ tonic zone, proposed by Farfulyak [2015], considers it as the Paleozoic North Crimean suture of Yudin [2008], formed as a result of the closure of the Paleotethys ocean during the Paleozoic-Triassic time span. New results, obtained in the framework of our IRG project in regards to the northern margin of the BS: 1) The new onshore struc­ tural data in the Crimean Mountains (CM) [Murovskaya et al., 2014; Sheremet et al., 2016b] and 2) the new structural offshore data (Sorokin Trough and Kertch Taman Trough) [Sheremet et al., 2016a; Sydorenko et al., 2016] allowed us to identify the structures developed in the CM and the northern mar­ gin of the BS in the context of two generalized phases of evolution: Mesozoic extension and Cenozoic compression. In the current presentation we propose an interpretation of the DOBRE-5 seismic model and show the development of the TZ between the EEP and SP during the Alpine orogenesis in the frames of the Crimean-BS evolution. Mesozoic extension. The red dashed line on Fig. 1 shows the projection of the transi­ tional zone (TZ) between EEP and SP on the DOBRE-5 profile; the zone itself is located to the north and has a ~W-E strike. According to the interpretation, the Paleozoic-Mesozoic basem ent of the SP is displaced by the gen­ tly dipping normal fault, reaching the Moho boundary: the thickness of the Paleozoic-Me­ sozoic deposits is twice thicker on the footwall than on the hanging wall of this fault. We suppose, that this listric fault (outlined by 1 in Fig. 1) plays an active role (also?) during the Cretaceous rifting. It is found the support in presence of a high-velocity body (HVLC in Fig. 1) detected in the lower crust in the area of Karkinit Trough. Such HVLC bodies are very typical for the rift zones. Cenozoic compression. The Paleozoic-Me­ sozoic basement of the SP (the Central Crime­ an uplift) includes the layers of increased velocities (FP=6.22^6.3 km/s) at the depth of 4— 15 km (See Fig. 1), which we interpret as the parts (blocks) of the pre-Riphean base­ ment, involved in the thrusting. The age of the compression postdates the Mesozoic, since the Mesozoic strata is affected by thrusts. Several detachments of gentle dipping at the depths of 15 and 7 km (denoted by 2 120 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017 SOUTH CAUCASUS GEOSCIENCES Fig. 1. Interpreted seismic model on the DOBRE-5 profile. and 3 in Fig. 1) we relate with the Cenozoic compression that most likely was released in two-stages: 1) during the Paleocene-Early Eocene, revealed by the recent structural and geological studies, onshore and offshore [Sheremet et al.r 2016a, b; Sydorenko et al.r 2016] and 2) in the latest Eocene — Pliocene which is also evident on many seismic profiles from the western and northwestern shelf of the BS [Khriachtchevskaia et al.r 2010; Mo- rosanu, 2012; Dinu et al.r 2005; M unteanu et al., 2013; Sheremet et al., 2016a; Sydorenko etal., 2016]. In the upper part of the interpreted cross­ References Gobarenko V. S., Murovskaya A. V, Yegorova T. R, Sheremet Y, 2016. Collisional processes at the north­ ern margin of the Black Sea. Geotectonics 50(4), 07—24. doi: 10.1134/S0016852116040026. Dinu C , Wong H. K., Tambrea D., Matenco L., 2005. Stratigraphic and structural characteristics of the Romanian Black Sea shelf. Tectonophysics 410, 417—435. doi: 10.1016/j.tecto.2005.04.012. Геофизический журнал Ns 4, T. 39,2017 section (See Fig. 1) we distinguished sev­ eral normal faults that affected the middle M iocene-Quaternary sediments, which we associate with the continuing loading of the western BS. In regards to the Eastern BS, here we observe the uplifting of the CM due to the collisional processes [Murovskaya et al., 2014; Gobarenko et al., 2016]. Detailed interpretation of the DOBRE-5 profile allowed clearing up the long tectonic evolution of the EEP with the formation of the TZ to the SP during the closure of the Pa- leotethys Ocean that imprints the Cretaceous extension and the Cenozoic compression. Farfulyak L. V., 2015. The nature of the inclined seis­ mic boundary in the Earth's crust of the Scythian microplate along the DOBRE-5 profile. Geophysical Journal 37(6), 23—39 (in Russian). Khriachtchevskaia O., Stovba S., Stephenson R., 2010. Cretaceous-Neogene tectonic evolution of the northen margin of the Black Sea from seismic re­ flection data and tectonic subsidence analysis. In: 121 INTERNATIONAL RESEARCH GROUP PROJECT M. Sosson, N. Kaymakci, R. A. Stephenson, F. Berger­ at, V Starostenko (Eds.). Sedimentary Basin Tecton­ ics from the Black Sea and Caucasus to the Arabian Platform. Geol. Soc. London Spec. Publ. Vol. 340, P. 37—157. Morosanu /., 2012. The hydrocarbon potential of the Romanian Black Sea continental plateau. Romanian Journal of Earth Sciences 86(is. 2), 91—109. Munteanu I., Willingshofer E., Sokoutis D., Matenco L., Dinu C., Cloetingh S., 2013. Transfer of deformation in back-arc basins with a laterally variable rheology: Constraints from analogue modelling of the Bal- kanides—Western Black Sea inversion. Tectonophys- ics 602, 223—236. doi: 10.1016/j.tecto.2013.03.009. Murovskaya A., Hippolite J.-C., Sheremet Ye., Yegoro- va T, Volfman Yu., Kolesnikova Ye., 2014. Deforma­ tion structures and stress field of the south-western Crimea in the context of the evolution of western Black Sea Basin. Geodinamika (2), 53—68 (in Rus­ sian). Sheremet Y, Sosson M„ Müller C„ Murovskaya A., Gintov O. B., Yegorova T., 2016a. Key problems of stratigraphy in the Eastern Crimea Peninsula: some insights from new dating and structural data. In: M. Sosson, R. Stephenson, Sh. Adamia (Eds.). Tec­ tonic Evolution of the Eastern Black Sea and Cauca­ sus. Geol. Soc. London Spec. Publ. 428. http://doi. org/10.1144/SP428.14. Sheremet Y, Sosson M., Ratzov G., Sydorenko G., Voits- itskiy Z., Yegorova T, Gintov O., Murovskaya A., 2016b. An offshore-onland transect across the north-eastern Black Sea basin (Crimean margin): ev­ idence of Paleocene to Pliocene two-stage compres­ sion. Tectonophysics 688, 84—100. doi: 10.1016/j. tecto.2016.09.015. Starostenko V. I., Janik T, Yegorova T, Farfuliak L., Czuba W, Sroda P, Thybo H„ Artemieva I., Sos­ son M., Volfman Yu., Kolomiyets K., Lysynchuk D., Omelchenko V, GrynD., GuterchA., KomminahoK., Legostaeva O., Tiira T, Tolkunov A., 2015. Seismic model of the crust and upper mantle in the Scythian Platform: the DOBRE-5 profile across the northwest­ ern Black Sea and the 676 Crimean Peninsula. Geo- phys. J. Int. 201, 406—428. doi:10.1093/gji/ggv018. Sydorenko G., Stephenson R., Yegorova T, Starosten­ ko V, Tolkunov A., Janik T, Majdanski M„ Voitsits- kiyZ., RusakovO., Omelchenko V., 2016. Geological structure of the northern part of the Eastern Black Sea from regional seismic reflection data including the DOBRE-2 CDP profile. Geol. Soc. London Spec. Publ. 428. doi: 10.1144/SP428.15. Yudin V. V., 2008. Geodynamics of the Black Sea—Cas­ pian Region. Kiev: UkrGGRI Publ., 117 p. (in Rus­ sian). Intraplate orogenesis © R. Stephenson, 2017 School of Geosciences, Geology and Petroleum Geology, Meston Building, King's College, University of Aberdeen, Aberdeen, UK Plate tectonics has it that major orogens form at plate boundaries, specifically in re­ sponse to collision of continental lithos­ pheric plates with other continental lithos­ pheric plates or island arc terranes and so on. A m ultitude of schematic diagrams have been published in the last 50 years showing black-coloured oceanic crust being sub­ ducted under white-coloured continents, continental fragments, other pieces of oce­ anic crust, often with subduction polarity flipped from one panel to another. Lately, abundant evidence, and a theoretical basis for it, has been published showing that many orogenic belts involve extreme shortening of previously severely thinned and often signif­ icantly intruded and infiltrated continental lithosphere but, nevertheless, continental lithosphere that was not breached or broken in a plate tectonic sense to produce a new lithospheric plate boundary at which new oceanic lithosphere is accreted. Although there are semantics involved, this cannot count as orogenesis at a plate boundary: it is, accordingly, «intraplate orogenesis». It seems likely to me that much of the large- scale compressional deformation recorded in the Alpine-Tethys belt might qualify as «intraplate orogenesis» in this regard and that many (if not all?) ophiolite complexes 122 Геофизический журнал Ne 4, T. 39, 2017 http://doi SOUTH CAUCASUS GEOSCIENCES ubiquitous in this belt do not represent ob- ducted crust of oceanic lithospheric affin­ ity but rather remnants of highly deformed, infiltrated and magmatised crust of conti­ nental lithospheric affinity. I'll review the lit­ erature published during the last years that supports this model and try to demonstrate some of the as yet not fully explored impli­ cations of such a model for the geodynamics of «intraplate orogenesis». Seismicity and crustal structure of the Southern Crimea and adjacent Northern Black Sea from local seismic tomography © T. Yegorova1, V. Gobarenko1, R. Stephenson2, M. Sosson3, 2017 'institute of Geophysics, National Academy of Sciences of Ukraine, Kiev, Ukraine 2School of Geosciences, Geology and Petroleum Geology, Meston Building, King's College, University of Aberdeen, Aberdeen, UK 3Université Côte d'Azur, UMR Géoazur, CNRS, Sophia Antipolis, France The Greater Caucasus and the Crimea M ountains constitute a fold-and-thrust belt that formed near the southern margin of Eur­ asia as a result of Cenozoic collision between Eurasia and the Africa—Arabian Plate. The Main Caucasus Thrust (MCT), which marks the southern boundary of the Greater Cauca­ sus orogen, can be traced westward along the northern margin of the Black Sea and coin­ cides at depth with a zone of seismicity called the Crimea Seismic Zone (CSZ). The CSZ is characterized by earthquakes of A4=3+5 with foci in the crust and uppermost mantle with abundant weak seismicity (M<3). The latter was used to recover the velocity structure of the crust of southern Crimea Peninsula and adjacent northern Black Sea employing local seismic tomographic tech­ niques. Events were recorded during 1970— 2013 by nine stations on the Crimea peninsula (Crimea Seismic Network; CSN) and by one station (Anapa) on the Caucasus coast of the eastern Black Sea. Data for the tomographic modelling, earthquake hypocentres, were relocated for the P- and S-wave arrivals at all perm anent stations of CSN. Earthquake relocation was done via error minimisation starting with a ID reference velocity model based on seismic surveys (active and passive) in the study area. The distribution of determined hypocen­ tres indicates three main seismicity subzones: 1) the Kerch-Taman subzone, which dips north­ ward at an angle of ~30° to a depth of 90 km; 2) the South Coast (or Yalta-Alushta) subzone, which dips to the southeast at an angle of ~18° with earthquake foci dominantly at depths of 10—25 km; 3) the Sevastopol subzone, which is orthogonal to the South Coast subzone and confines it from the west, characterised by dif­ fuse seismicity to a depth of ~40 km. The new local tomographic results docu­ ment significant P- and S-wave velocity het­ erogeneities in the depth range 10—30 km. Stable solutions have been obtained for depths of 15, 20 and 25 km. A distinctive fea­ ture of the crust of Crimea M ountains (west­ ern Crimea) is the presence of a high-velocity (6.7—6.8 km/s) domain of complex configura­ tion, comprising a number of separate bodies. It is separated from the more eastern Crimea and Kerch peninsula by a linear low-velocity zone of ~N-S strike (in the Sudak area) in­ terpreted as a manifestation of a weakened crustal zone, possibly associated with the Feodosiya Fault expressed at the surface, Геофизический журнал Ns 4, T. 39, 2017 123 INTERNATIONAL RESEARCH GROUP PROJECT which, in turn, could be linked to a collinear Proterozoic N-S trending fault zone in the Ukrainian Shield. From other side, it could be indication of a normal fault zone related to the Early Cretaceous rifting and opening of the East Black Sea Basin. To the east of this low-velocity zone the crustal structure lacks notable velocity anomalies. Preliminary interpretation of velocity anomalies suggests that complex 3D crustal geometries are involved. The relocated hy- pocentres in combination with the tomogra­ phy models show that there is a change of underthrusting polarity in the western Crimea Mountains crust compared to eastern Crimea. This may be a reflection of structural inheri­ tance and reactivation during compression of the same deeper structures that earlier con­ trolled formation of the mid-Black Sea Rise during Black Sea extension. 124 Teo(pu3UHecKuû. xypnoA Ne 4, T. 39, 2017

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