The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)

The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)

The paper presents the results of reinterpretation of the materials obtained as a result of studies using the DSS method along the IV geotraverse at the site PK 295—400.

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Дата:2019
Автори: Trypolsky, O.A., Topoliuk, O.V., Gintov, O.B.
Формат: Стаття
Мова:English
Опубліковано: Інститут геофізики ім. С.I. Субботіна НАН України 2019
Назва видання:Геофизический журнал
Онлайн доступ:http://dspace.nbuv.gov.ua/handle/123456789/158493
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Цитувати:The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400) / O.A. Trypolsky, O.V. Topoliuk, O.B. Gintov // Геофизический журнал. — 2019. — Т. 41, № 1. — С. 172-179. — Бібліогр.: 12 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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spelling irk-123456789-1584932019-09-04T01:25:21Z The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400) Trypolsky, O.A. Topoliuk, O.V. Gintov, O.B. The paper presents the results of reinterpretation of the materials obtained as a result of studies using the DSS method along the IV geotraverse at the site PK 295—400. Представлены результаты переинтерпретации материалов, полученных при исследованиях методом ГСЗ по IV геотраверсу на участке ПК295―ПК400. Представлені результати переінтерпретації матеріалів, отриманих при дослідженнях методом ГСЗ по IV геотраверсу на ділянці ПК295-ПК400. 2019 Article The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400) / O.A. Trypolsky, O.V. Topoliuk, O.B. Gintov // Геофизический журнал. — 2019. — Т. 41, № 1. — С. 172-179. — Бібліогр.: 12 назв. — англ. 0203-3100 DOI: 10.24028/gzh.0203-3100.v41i1.2019.158870 http://dspace.nbuv.gov.ua/handle/123456789/158493 550.834:553 en Геофизический журнал Інститут геофізики ім. С.I. Субботіна НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
language English
description The paper presents the results of reinterpretation of the materials obtained as a result of studies using the DSS method along the IV geotraverse at the site PK 295—400.
format Article
author Trypolsky, O.A.
Topoliuk, O.V.
Gintov, O.B.
spellingShingle Trypolsky, O.A.
Topoliuk, O.V.
Gintov, O.B.
The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)
Геофизический журнал
author_facet Trypolsky, O.A.
Topoliuk, O.V.
Gintov, O.B.
author_sort Trypolsky, O.A.
title The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)
title_short The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)
title_full The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)
title_fullStr The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)
title_full_unstemmed The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400)
title_sort structure of the earth’s crust of the central part of the holovanivsk suture zone according to the reinterpretation of materials of iv geotraverse of dss (pk 295—400)
publisher Інститут геофізики ім. С.I. Субботіна НАН України
publishDate 2019
url http://dspace.nbuv.gov.ua/handle/123456789/158493
citation_txt The structure of the Earth’s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295—400) / O.A. Trypolsky, O.V. Topoliuk, O.B. Gintov // Геофизический журнал. — 2019. — Т. 41, № 1. — С. 172-179. — Бібліогр.: 12 назв. — англ.
series Геофизический журнал
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AT topoliukov thestructureoftheearthscrustofthecentralpartoftheholovanivsksuturezoneaccordingtothereinterpretationofmaterialsofivgeotraverseofdsspk295400
AT gintovob thestructureoftheearthscrustofthecentralpartoftheholovanivsksuturezoneaccordingtothereinterpretationofmaterialsofivgeotraverseofdsspk295400
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fulltext O. A. TRYPOLSKY, O. V. TOPOLIUK, O. B. GINTOV 172 Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 ÓÄÊ 550.834:553 The structure of the Earth�s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295�400) O. A. Trypolsky, O. V. Topoliuk, O. B. Gintov, 2019 Subbotin Institute of Geophysics of the National Academy of Sciences of Ukraine, Kyiv, Ukraine Received 21 Desember 2018 Íàâåäåíî ðåçóëüòàòè ïåðå³íòåðïðåòàö³¿ ìàòåð³àë³â, îòðèìàíèõ ï³ä ÷àñ äîñë³äæåíü ìåòîäîì ÃÑÇ ïî IV ãåîòðàâåðñó íà ä³ëÿíö³ ÏÊ 295�400. Ïåðå³íòåðïðåòàö³þ âèêî- íàíî ö³ëåñïðÿìîâàíî äëÿ óòî÷íåííÿ ñåéñì³÷íîãî ðîçð³çó â ðàéîí³ Ãîëîâàí³âñüêîãî ìàêñèìóìó ñèëè òÿæ³ííÿ (ÏÊ 320�360). Ó çåìí³é êîð³ íà ãëèáèíàõ 2�60 êì äîäàò- êîâî âèä³ëåíî ñåéñì³÷í³ ïëîùàäêè ³ òî÷êè äèôðàêö³¿, ùî äàëî çìîãó ñêëàñòè îá�ºê- òèâíå óÿâëåííÿ ïðî ãëèáèííó áóäîâó ðîçãëÿíóòî¿ ÷àñòèíè ãåîòðàâåðñó. Ïîð³âíÿíî ç ïîïåðåäí³ìè ³íòåðïðåòàö³ÿìè ðîçð³ç çåìíî¿ êîðè çíà÷íî óòî÷íåíî. Âíàñë³äîê âèä³- ëåííÿ äîäàòêîâèõ òî÷îê äèôðàêö³¿ òà âåëèêî¿ ê³ëüêîñò³ êîðîòêèõ â³äáèâíèõ åëåìåí- ò³â íà ãëèáèíàõ 2�8 êì óòî÷íåíî ïîëîæåííÿ â ðîçð³ç³ Òàëüí³âñüêî¿ çîíè ðîçëîì³â. Ó öåíòðàëüí³é ÷àñòèí³ ðîçð³çó (ÏÊ 338�ÏÊ 355) íà ãëèáèíàõ 8�26 êì óñòàíîâëå- íî ñåð³þ êîðîòêèõ êðóòîíàõèëåíèõ â³äáèâíèõ åëåìåíò³â. Ó ñóêóïíîñò³ ç åëåìåíòà- ìè, ùî ìàþòü ãîðèçîíòàëüíå ³ ïîõèëå çàëÿãàííÿ (ãëèáèíè 2�9 ³ 24�44 êì), âîíè ôîðìóþòü çîíó ñåðåäîâèùà, ÿêà íà ãëèáèíàõ 2�44 êì çà õàðàêòåðèñòèêàìè â³äð³ç- íÿºòüñÿ â³ä âì³ñíèõ ïîð³ä. Ó ðåçóëüòàò³ ïðîñòåæåíî ë³ñòðè÷íó çîíó ñêîëþâàííÿ, ÿêà áåçïåðåðâíî ïðîñòÿãàºòüñÿ ç ãëèáèíè 8 êì íà ÏÊ 355 äî 44 êì íà ÏÊ 304. Ç óðà- õóâàííÿì ñåéñìîòîìîãðàô³÷íèõ äàíèõ ïðèïóùåíî, ùî Òàëüí³âñüêà çîíà ðîçëîì³â ïðîñòåæóºòüñÿ äî ãëèáèí 100�600 êì ó âèãëÿä³ ìåæ³ ì³æ áëîêàìè ç ð³çíèìè øâèä- êîñòÿìè VP, óñòóïàìè ³ ðîçðèâàìè â øàð³ Ãîëèöèíà�Ãåéêà. Ïîáëèçó çåìíî¿ ïî- âåðõí³ ë³ñòðè÷íà çîíà ñêîëþâàííÿ ç�ºäíóºòüñÿ ç îñíîâíîþ ÷àñòèíîþ Òàëüí³âñüêî¿ çîíè ðîçëîì³â. Çã³äíî ç îñòàíí³ì âàð³àíòîì ïåðå³íòåðïðåòàö³¿ äàíèõ ÃÑÇ, ï³äâ³äíèé êàíàë ³íòðóçèâíîãî ò³ëà ãèïåðáàçèò³â íà ãëèáèíàõ 60�33 êì äîñèòü âóçüêèé ³ ò³ëüêè ïî÷èíàþ÷è ç ãëèáèíè 30 êì ³ ìàéæå äî ïîâåðõí³ ò³ëî ðîçøèðþºòüñÿ äî òîâùèíè áëèçüêî 15 êì. Ñàìå òàêîþ º øèðèíà âèõîä³â ã³ïåðáàçèò³â íà ïîâåðõíþ êðèñòàë³÷- íîãî ôóíäàìåíòó íà ä³ëÿíö³ ó ï³âäåííîìó íàïðÿìêó â³ä ãåîòðàâåðñó IV . Îð³ºíòóþ- ÷èñü íà çîíó ï³äâèùåíèõ øâèäêîñòåé VP íà ãëèáèíàõ 2�33 êì, ìîæíà ïðèïóñòèòè, ùî ñàìå íà öèõ ãëèáèíàõ óçäîâæ îñ³ öåíòðàëüíî¿ ÷àñòèíè Ãîëîâàí³âñüêî¿ øîâíî¿ çîíè ðîçì³ùóºòüñÿ îñíîâíå ò³ëî ³íòðó糿 ã³ïåðáàçèò³â ³ áàçèò-äóí³ò³â, ïåðèäîòèò³â, ï³ðîêñåí³ò³â, ãàáðî, àìô³áîë³ò³â, ãóñòèíà ÿêèõ ïåðåâèùóº ãóñòèíó âì³ñíèõ ïîð³ä íà 0,1�0,22 ã/ñì3. Êëþ÷îâ³ ñëîâà: Ãîëîâàí³âñüêà øîâíà çîíà, Ãîëîâàí³âñüêèé ìàêñèìóì ñèëè òÿæ³í- íÿ, ÃÑÇ, IV ãåîòðàâåðñ, øâèäê³ñòü ïîøèðåííÿ ñåéñì³÷íèõ õâèëü. Introduction. In terms of studying the deep structure of the lithosphere of the Uk- rainian Shield geotraverse IV is the key one because of its location in the territory of al- most all megablocks of the shield and the cross section across the stretch of such deep fault zones, as Talnivska, Kryvorizsko-Kre- menchutska and Orihovo-Pavlogradska, which define the tectonic zoning of the Ukrainian Shield, and, accordingly, suture zones � Ho- lovanivsk, Inguletsko-Kryvorizka and Oriho- vo-Pavlogradska. doi: 10.24028/gzh.0203-3100.v41i1.2019.158870 THE STRUCTURE OF THE EARTH�S CRUST ... OF IV GEOTRAVERSE OF DSS ... Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 173 Within Pobuzkyi ore area the geotraverse crosses the Holovanivsk high gravity in the latitudinal direction (Fig. 1) and passes near the well-known basic massifs � Troianskyi and Tarasivskyi and slightly to the north of the region of the surface of the crystalline basement of abnormally large amounts (mo- re than 100) areas of serpentine and peri- dots, which are associated with the develo- pment of deposits of silicate nickel and chromites. This has given the interpretati- on of the seismic data obtained here a lot of weight. The re-interpretation of the results of the research with the method DSS geotraverse IV was made in early 2000-ies [Trypolsky, Sharov, 2004], and more recently the re- sults of the research method DSS on the part of geotraverse IV the authors delibe- rately revised in order to clarify the seis- mic section in the Holovanivsk area of high gravity (PK 320�360). This was provided by a detailed system of observations. In the earth�s crust at depths of 2�60 km from a number of seismic sites and points of dif- fraction can be obtained that gives the op- portunity to build an objective picture of the deep structure of the study of geotra- verse. To the west of PK 360 for the lack of a detailed system of observations it was impossible. In previous interpretations, the seismic section approximately at the depth of the Moho boundary was extended westward to PK 410 [Sollogub, Trypolsky, 1969; Sollogub et al., 1972; Subbotin et al., 1976; Sollogub, 1986; Trypolsky et al., 1984, 1988]. Later, du- ring the reanalysis of seismic materials, this part of the section was partially removed or reviewed [Trypolsky, Sharov, 2004]. The re- ason for this removal was as follows. First, in this segment of the seismic pro- Fig. 1. Schematic map of the gravitational field and the location of the ge- otraverse IV . The oval contour outlines the area of the exit to the surface of the crystalline basement of the bulk of the bodies of hyperbasites. O. A. TRYPOLSKY, O. V. TOPOLIUK, O. B. GINTOV 174 Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 file, work was done under the condition of the lack of a detailed system of observati- ons. Second, a significant part of the deep constructions was carried out due to the partial absence of reverse hodographs, agreed upon at mutual points. This led to the poor quality of the results, which forced to abandon them almost completely. Observations on geo-traverse IV were carried out by the method of continuous Fig. 3. Seismic section of the Earth�s crust along geotraverse IV (PK 295�400): 1 � velocity conto- urs, km/s; 2 � conditional boundary separating geotraverse areas with different initial velocities; 3 � reflecting elements in the Earth�s crust; 4 � diffraction points; 5 � seismic boundary K2; 6 � seismic boundary Moho; 7 � deep fault. Fig. 2. Seismogram PK 320, PK 326.8�331.5. The rectangle highlights the area where the axes with negative apparent velocities are fixed. THE STRUCTURE OF THE EARTH�S CRUST ... OF IV GEOTRAVERSE OF DSS ... Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 175 profiling provided for the registration of the system of direct and reverse hodographs of the main waves agreed upon at mutual points. The distance between the explosion points was 20�35 km, the length of conti- nuous hodographs � up to 250�350 km, the distance between the recorders � 100 m. Under frequency registration are 7�20 Hz and velocity of propagation of seismic waves in the range 5.7�8.3 km/s wavelengths changed in the range of 200�1200 m (most- ly 400�700 m). The distance between the recorders was significantly less than half the wavelength that provided a reliable cor- relation of all waves recorded during field observations. In general, the section has features that are typical for the most of the DSS profiles in the territory of the Ukrainian Shield. In the upper part of the section at depths of 0�14 km refracted waves ê 0P can be seen everywhere in the distance of 0�80�120 km from the point of excitation (Fig. 2). At depths of 5�13 km on a segment of PK 295�350 the layer with the lowered velocity below which the seismic boundary K2 that represents a sole of this layer lies is observed. With the exception of this layer, the velocities in the Earth�s crust gradually and continuously increase to the depth of the Moho boundary (Fig. 3). In comparison with previous interpreta- tions of the considered part of geotraverse [Sollogub, 1986, p. 85, Fig. 31; Trypolsky, Sharov, 2004, p. 26, Fig. 9] the section of the Earth�s crust is considerably refined. In the upper part of the Earth�s crust (depth 0�5 km) velocity compared to their normal values increased (the difference is 0.1�0.2 km/s). With depth, the measure of velocity increase gradually decreases from + 0.18 km/s at a depth of 15 km to + 0.04 km/s at a depth of 40 km. Velocity in the horizontal direction chan- ges mostly insignificantly. The exception is the area of PK 340�335, where at depths of 18�30 km there are local maxima of velocities (the area of the deep fault), which corresponds to the maximum of the gravi- tational curve and may indicate the con- centration at these depths of rocks of more basic composition. In the time interval between the soles of the layer with reduced velocity and reflect- ed waves from the Moho boundary, super- critical reflected waves from the bounda- ries lying slightly below the sole of this lay- er (depths of 13�18 km) are recorded. As a rule, the reflected waves from these bo- undaries are traced parallel to each other in the absence of interference between them (see Fig. 3). In the Earth�s crust in the area of PK 340�355 at depths of 16�26 km and 30� 40 as a result of registration of diffracted waves, a number of diffraction points are additionally identified. The projection of the diffraction point on the day surface is the minimum of the hodograph. The depth of the diffraction point was determined using a ray diagram. Diffracted waves are often recorded in deep fault zones of different ranks. Genera- lization and analysis of DSS materials show that the presence of diffracted waves in the recorded wave pattern is one of the re- liable criteria for identifying deep faults in the Earth�s crust. Defining of additional diffraction points, as well as a dense series of short seismic boundaries at depths of 2�8 km allowed clarify the position of the Talnivska fault zone in the section. On the surface of the crust geotravers crosses it in the area of PK 350�360. A dense series of short seis- mic boundaries at depths of 2�8 km can be traced to the east of PK 353. It is impos- sible to trace it to the west because of the change in the system of observations to a less detailed one. Therefore, considering the position of Talnivska area on the surface [Gintov et al., 2016], in the cut (see Fig. 3) the western limit of the depicted level PK 357. The eastern limit of the zone within the upper part of the crust is not determi- ned through a continuous tectonics destro- yed Golovanivsk Suture Zone and the pre- sence of several fault zones, in particular Yemylivska. And in the lower crust, the zone is traced by diffraction points to a depth of O. A. TRYPOLSKY, O. V. TOPOLIUK, O. B. GINTOV 176 Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 60 km (the zone of rupture in the Moho surface) within the limits of PK 345�355. It should be noted that the Talnivska fault zone marks the border between the Buzkyi and Rosynskyi megablocks on the one hand and the Ingulskyi [Gintov et al., 2018a], block on the on the other. Accord- ing to seismotomographic data [Geyko et al., 2005, p. 935, Fig. 6], this border can be traced at the intersection of 47�50° of north latitude and at the longitudes 30� 31° east longitude at depths of 100�600km in a boundary between blocks with diffe- rent velocities VP and degrees and gaps in the layer of the Golitsyn�Geyko. Therefo- re, we can assume that Talnivska area is al- so seen at these depths. On the surface it is established by brittle-plastic deformati- on of rocks, and at considerable depths, for example, it is expressed by the structure of the subvertical flow of mantle matter. Most of the section of the Earth�s crust of the considered area of geotraverse IV is characterized, as usual, by horizontal and subhorizontal occurrence of individual seis- mic boundaries and mainly by a gradual increase in velocity with depth. The excep- tion is the central part of the section (PK 328�355), where at depths of 8�26 km a series of sharply inclined reflective elements are distinguished. The method of construction of steeply inclined reflecting elements was as follows. Initially, the beam of the descending wave was reproduced by means of the beam dia- gram. For this purpose, the zero of the radi- ation diagram was located at the excitation point (in our case, this is the point of explo- sion). Next, the beam of the downward wa- ve is reproduced with the start of the refer- ence time on the beam from zero to seve- ral seconds. The angle of incidence (α) was calculated according to the formula α = arc- sin (V0 /V*), where V0 is the initial velocity, V* is the apparent velocity measured along the line of sight to the element of the hodo- graph, which corresponds to the site, the depth of which has to be determined. Then the reflected wave beam is reproduced. At the point of exit of the beam to the day sur- face zero beam diagram is placed, from which the time of arrival of the wave along the beam in the direction of decreasing ti- me. The angle of the beam is calculated by the same formula as in the case of a down- ward wave. At the intersection of these rays there is a reflective element that is normal to the bisector of the angle between them. The length of the reflecting element is 0.5 of the section of the profile on which this element is registered. In our case, due to the registration of waves with negative ve- locities, the beam of the downward wave is reproduced not in the direction of the regi- stration point of the reflected beam, and in the opposite direction, which corresponds to the negative velocity. It should be emphasized that the positi- on of sharply inclined reflective elements in the plan is shifted by 10�15 km in the west direction from the place where they should lie at their horizontal position. This deviation is accompanied by a significant increase in the intensity of reflections from these elements. All these reflecting elements together with horizontally lying elements (depths of 2�9 km) form the area of the medium, which at depths of 2�30 km dif- fers in its characteristics from the host rocks. The series has one characteristic feature � most of the axes are parallel to each other. This means that the associated re- flective elements are likely to be parallel to each other as well. It follows from this con- clusion that in the crystalline thickness of the Earth�s crust revealed a structure com- posed of a large number of reflective ele- ments that fall steeply to the east and in general lie quite comfortable. The physical nature of these reflections can be explained as follows. Reflections are formed only, when the wave on its way me- ets the change in the acoustic impedance of the medium γ (γ = ρν, where ρ is the densi- ty, ν is the velocity, km/s). In this case, the reflection occurs from the boundary, which characterizes the change in the acoustic im- pedance of the medium. In our case, it can be the surface of some individual layers that divide the medium into separate lay- THE STRUCTURE OF THE EARTH�S CRUST ... OF IV GEOTRAVERSE OF DSS ... Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 177 ers, the velocity of which differs from the velocity on their surface. Under this assump- tion, there are physical prerequisites for the formation of reflections from the surfaces of the layers. It can be assumed that this series is composed of partially parallel bo- dies with reduced and increased velocities with a predominance of the latter. A series of inclined reflective elements continues to the west and to the mountains at the level of 8�9 km under PK 352, as well as to the east and to a depth of 37 km under PK 315. This gives one the ability to track the listric zone of shear which con- tinuously extends from a depth of 8 km on a PK 355 to 44 km on a PK 304. The zone characterized by width (up to 10 km) at depths of 20�24 km, where it coincides with a series of steeply inclined reflective elements and several diffraction points. Near the surface area the highlighted listric spallation is combined with the main part of the Talnivska fault zone. Tectono- physical studies [Gintov et al., 2016] within the Talnivska zone mapped one several sub- parallel zones of cleavage of southeast stri- ke, one of which is likely to be this listric zone, while others can be traced to a depth of the subvertical ones. Developing the mag- netic model of the Earth�s crust GSZ, I. K. Pashkevich and M. I. Bakarzhieva [Gintov et al., 2018b, p. 398, Fig. 2.183] already sug- gested the presence here of the listric zone, which has megablock bug slips under GSZ, or the latter prolonged to Buzkyi megablock. In the area of PK 335�340, a deep fault along the Moho boundary is known to be recorded, along which it vertically shifts from a depth of 43 km to a depth of 53 km (PK 335�340). In addition, a number of dif- fraction points are allocated in the Earth�s crust at the same place (see Fig. 3). In the context of this section geotraverse, V. B. Sollogub [Sollogub, 1986, p. 85, Fig. 31] allocated intrusive body with high den- sity in the depth interval of 10�50 km and horizontal dimensions of the body � 3�14 km at depths of 10�20 km and 6�14 km at depths of 20�50 km at the surface (at a depth of 4�10 km) and intrusion deviates to the east and narrows to 3 to 4 km from the intrusive body, according to the inter- pretation of V .B. Sollogub, spatially coin- cides with a vertical deep fracture and gra- dually narrowing with depth. The fault can be traced to a depth of 50 km. According to three-dimensional gravity modeling [Starostenko et al., 2018] the de- gree of section of the Moho depth and the corresponding fault can be traced in N-G direction through the central part of the GSZ. In the field of Bouguer anomalies the degree of Moho amplitude up to 10 km is compensated with increased capacity of crust�mantle mixture in the closed west wing and the largest within the Ukrainian Shield gravitational anomaly (Golovanivsk maximum) due to the raising of the �ba- salt� and �diorite� of the layers of the plate which have a width of 40 km is raised with respect to adjacent to 4�10 km. The pres- ence of an intrusive body above the stage of the Moho, supposed by V. B. Sollogub, was not taken into account because of the expected nature of the body and its uncer- tain power. According to the latest version of the re-interpretation of DSS data (see Fig. 3) supply channel of intrusive bodies at depths of 60�33 km is quite narrow and only start- ing from 30 km almost to the surface of the body extends to power about 15 km away. It is the width of the of ultrabasites out- cropping at the surface of the crystalline basement in the area south of geotraverse IV (see Fg. 1). Focusing on the region of relatively high velocities VP at depths of 2� 33 km (see Fig. 3), it can be expected that at these depths along the axis of the cent- ral part of the GSZ there is the main body of the intrusion of hyperbasites and basites- dunite, peridotite, pyroxenite, Gabro, am- phibolite � density which exceeds the den- sity of host rocks is 0.1�0.2 g/cm3. At the surface at depths up to 2�3 km, the hy- perbasites are serpentinized, that is why the intensity of the gravitational field in the re- gion of their cropping out to the surface (see Fig. 3) is slightly reduced. And in pla- ces of the outcrops of crystalline basement O. A. TRYPOLSKY, O. V. TOPOLIUK, O. B. GINTOV 178 Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 rocks � in Troianskyi and Tarasivakyi are- as � there is a maximum intensity of the Holovanivsk anomaly. Thus, the reinterpretation section of the Holovanivsk section of geotraverse IV sig- nificantly clarifies the previous sections, which should be taken into account in the analysis of other geophysical data. Conclusions. 1. The result of re-inter- pretation of the data of geotraverse IV in the interval PK 300�400 a new series of reflection and diffraction points was defined, which gave the possibility to clarify the situ- ation in the context of the Talnivska of the rift and its internal structure, as well as to confirm and clarify the form of the intru- sions of basic and ultrabasic rocks predict- ed by V. B. Sollogub. The structure of the Earth�s crust of the central part of the Holovanivsk suture zone according to the reinterpretation of materials of IV geotraverse of DSS (PK 295�400) O. A. Trypolsky, O. V. Topoliuk, O. B. Gintov, 2019 The paper presents the results of reinterpretation of the materials obtained as a re- sult of studies using the DSS method along the IV geotraverse at the site PK 295�400. The reinterpretation was carried out purposefully to clarify the seismic cross section in the area of the Holovanivsk gravity maximum (PK 320�360). A number of seismic sites and diffraction points were additionally identified in the crust at the depths of 2�60km, which made it possible to form an objective idea of the deep structure of the conside- red part of geotraverse. The observations were carried out according to the method of continuous profiling, which provided for the registration of a system of direct and in- verse hodographs of the main waves, linked at the inter-points. Compared to previous interpretations, the cross-section of the crust was significantly specified. The identifica- tion of additional diffraction points and a large number of short reflecting elements at the depths of 2�8 km made it possible to clarify the position of snaps in the cross sec- tion of the Talnivska zone. A series of short steeply inclined reflecting elements was iden- tified in the central part of the cross-section (PK 338�355) at the depth of 8�26 km. Together with horizontally and obliquely lying elements (at the depth of 2�9 km and 24�44 km), they form an environ area that differs according to its features from the host rocks at the depth of 2�44 km, which made it possible to retrace the listric shear zone that continuously extends from the depth of 8 km at PK 355 to 44 km at PK 304. Taking into account the seismic tomographic data, it was suggested that the Talnivska zone of snaps can be retraced to the depth of 100�600 km as a boundary between blocks with different velocities VP and steps and breaks in the Golitsyn�Geyko layer. Close by the daylight surface, the listric shear zone is connected to the main part of the Tal- nivska fault zone. According to the latest version of the reinterpretation of the DSS data, the feeder of the intrusive body of hyperbasites is quite narrow at the depth of 60�33 km 2. The considered part of geotraverse IV is characterized by the feature that dis- tinguishes it from other parts � it is a se- ries of steep reflective elements occurring at depths of 8�26 km. Taking into account other inclined and horizontal reflective ele- ments it is possible to trace listric spallation zone of Talnivska fault zone that was as- sumed here on other geological and geo- physical data. 3. It is shown that intrusion of basic and ultrabasic rocks within the Holovanivsk su- ture zone forms a body with size of about 15 km width and 30 km in the vertical part, not taking into account the supply chan- nel. Such a body should be considered in the following quantitative geophysical cal- culations. THE STRUCTURE OF THE EARTH�S CRUST ... OF IV GEOTRAVERSE OF DSS ... Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 41, 2019 179 References Geyko, V. S., Tsvetkova, T. A., Shumlyanska- ya, L. A., Bugaenko, I. V., & Zaets, L. N. (2005). Regional model 3D P speed mantle of Sarma- tia (south-west of the East-European platform). Geofizicheskiy zhurnal, 27(6), 927�939 (in Russian). Gintov, O. B., Entin, V. A., Mychak, S. V., Pav- lyuk, V. N., & Zultsle, V. V. (2016). Structu- ral-petrophysical and tectonophysical base of geological map of crystalline basement of the central part of Golovanevsk suture zone of the Ukrainian Shield. 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Geofizicheskiy sbornik AN USSR, (31), 5�24 (in Russian). and expands to a thickness of about 15 km only starting from 30 km and almost to the body surface. This is precisely the width of the hyperbasites outbreaks onto the surface of the crystalline basement in the area to the south of the IV geotraverse. Focusing on the area of relatively high velocities VP at the depth of 2�33 km, it can be assumed that the main body of the intrusion of hyperbasites and basit-dunites, peridotites, pyro- xenites, gabbro and amphibolites, the density of which exceeds the density of the host rocks by 0.1�0.22 g/cm3, is located particularly at these depths along the axis of the central part of the Holovanivsk suture zone. Key words: Holovanivsk suture zone, Holovanivsk gravity maximum, DSS, IV geo- traverse, the velocity of seismic waves. Sollogub, V. B., Chekunov, A. V., & Tripolsky, O. A. (1972). Tectonic zoning of the Ukrainian Shield in the light of data of deep geophysical in- vestigations. 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Features of seismic stratification of the Earth�s crust of the Kirovograd block. Geofizicheskiy zhurnal, 6(3), 88�94 (in Rus- sian). Tripolsky, A. A., & Sharov, N. V. (2004). Litho- sphere of the Precambrian Shields of the northern hemisphere of the Earth according to seismic data. Petrozavodsk: Karelian Re- search Centre RAS, 159 p. (in Russian).

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