Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault

Highly detailed, very accurate ground magnetic investigations were jointly conducted by Romanian and Ukrainian researchers on a segment of the Peceneaga-Camenas Fault (PCF) in order to reveal the potential of geomagnetic method for active faults investigating. The survey succeeded to outline the PCF...

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Datum:	2014
Hauptverfasser:	Besutiu, L., Orlyuk, M., Zlagnean, L., Roments, A., Atanasiu, L., Makarenko, I.
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Veröffentlicht:	Інститут геофізики ім. С.I. Субботіна НАН України 2014
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spelling	irk-123456789-1001972016-05-18T03:02:12Z Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault Besutiu, L. Orlyuk, M. Zlagnean, L. Roments, A. Atanasiu, L. Makarenko, I. Highly detailed, very accurate ground magnetic investigations were jointly conducted by Romanian and Ukrainian researchers on a segment of the Peceneaga-Camenas Fault (PCF) in order to reveal the potential of geomagnetic method for active faults investigating. The survey succeeded to outline the PCF track in the area covered by recent sediments, and provide insights on the fault structure and in-depth development. 2D numerical modeling has been employed for interpreting the obtained geomagnetic anomaly. Lateral variations in magnetization, as suggested by the model, reveal the complex geological architecture in the area, hidden by recent deposits. The zero magnetization outlined in the central part of the survey lines has been interpreted in geodynamic terms, as a breccias zone created along PCF track by its active dynamics. С целью оценки возможностей геомагнитного метода при изучении активных разломов совместно с румынскими и украинскими учеными были выполнены высокоточные наземные исследования Печенежско-Каменского разлома (ПКР). Съемка позволила проследить положение ПКР под современными осадочными образованиями и получить представление о его глубинной структуре. Интерпретация выделенных вдоль профилей магнитных аномалий была выполнена с помощью двумерного численного моделирования. В соответствии с моделью, латеральные вариации намагниченности исследуемой зоны свидетельствуют о сложном геологическом строении, скрытом под молодыми осадками. Область коры с нулевой намагниченностью, которая выделена в центральной части геомагнитных профилей, проинтерпретирована с геодинамичеких позиций как пояс брекчированных пород, образованных вдоль ПКР вследствие активных перемещений по нему. 2014 Article Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault / L. Besutiu, M. Orlyuk, L. Zlagnean, A. Roments, L. Atanasiu, I. Makarenko // Геофизический журнал. — 2014. — Т. 36, № 1. — С. 133-144. — Бібліогр.: 30 назв. — англ. 0203-3100 http://dspace.nbuv.gov.ua/handle/123456789/100197 550.389:550.838 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	Highly detailed, very accurate ground magnetic investigations were jointly conducted by Romanian and Ukrainian researchers on a segment of the Peceneaga-Camenas Fault (PCF) in order to reveal the potential of geomagnetic method for active faults investigating. The survey succeeded to outline the PCF track in the area covered by recent sediments, and provide insights on the fault structure and in-depth development. 2D numerical modeling has been employed for interpreting the obtained geomagnetic anomaly. Lateral variations in magnetization, as suggested by the model, reveal the complex geological architecture in the area, hidden by recent deposits. The zero magnetization outlined in the central part of the survey lines has been interpreted in geodynamic terms, as a breccias zone created along PCF track by its active dynamics.
format	Article
author	Besutiu, L. Orlyuk, M. Zlagnean, L. Roments, A. Atanasiu, L. Makarenko, I.
spellingShingle	Besutiu, L. Orlyuk, M. Zlagnean, L. Roments, A. Atanasiu, L. Makarenko, I. Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault Геофизический журнал
author_facet	Besutiu, L. Orlyuk, M. Zlagnean, L. Roments, A. Atanasiu, L. Makarenko, I.
author_sort	Besutiu, L.
title	Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault
title_short	Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault
title_full	Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault
title_fullStr	Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault
title_full_unstemmed	Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault
title_sort	geomagnetic insights on an active tectonic contact: peceneaga-camena fault
publisher	Інститут геофізики ім. С.I. Субботіна НАН України
publishDate	2014
url	http://dspace.nbuv.gov.ua/handle/123456789/100197
citation_txt	Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault / L. Besutiu, M. Orlyuk, L. Zlagnean, A. Roments, L. Atanasiu, I. Makarenko // Геофизический журнал. — 2014. — Т. 36, № 1. — С. 133-144. — Бібліогр.: 30 назв. — англ.
series	Геофизический журнал
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first_indexed	2025-07-07T08:31:37Z
last_indexed	2025-07-07T08:31:37Z
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fulltext	�� !"#$ % &' () +' ,-&. &* �� 550.389:550.838 Peceneaga-Camena Fault: Geomagnetic insights into active tectonic contact ©©©©© L. Besutiu 1, M. Orlyuk 2, L. Zlagnean 1, A. Romenets 2, L. Atanasiu 1, I. Makarenko 2, 2014 1Institute of Geodynamics of the Romanian Academy (IGAR), Bucharest, Romania 2 Institute of Geophysics National Academy of Sciences of Ukraine, Kiev, Ukraine Received 18 July 2013 Presented by Editorial Board Member V. I. Starostenko Highly detailed, very accurate ground magnetic investigations were jointly conducted by Ro- manian and Ukrainian researchers on a segment of the Peceneaga-Camenas Fault (PCF) in order to reveal the potential of geomagnetic method for active faults investigating. The survey succeeded to outline the PCF track in the area covered by recent sediments, and provide in- sights on the fault structure and in-depth development. 2� numerical modeling has been em- ployed for interpreting the obtained geomagnetic anomaly. Lateral variations in magnetization, as suggested by the model, reveal the complex geological architecture in the area, hidden by recent deposits. The zero magnetization outlined in the central part of the survey lines has been interpreted in geodynamic terms, as a breccias zone created along PCF track by its active dy- namics. Key words: magnetic survey, magnetization, residual geomagnetic anomaly, modeling, faults, geodynamics. �� ©©©©©�� ! �� "�#�� !�� $#�%&'��(�� ! �� #�%�� "�� ! �� '�) ��"�� � �� ! �� + �� "'�,��! �� -� �� ! �� -�� '�. ! �� -��"�� ! �� � ��-�� "�� ! �� -�� #�%�� +� �� ' � �� /�� "��(��-� �� -�� "�� "�� ! �� "-�� -�� -�� ' ) /��' ) �0 1�2' ) 3 ��' �) 0� ��' ) ��' �) �2�0��2� &. �� !"#$ % &' () +' ,-&. General consideration. The Peceneaga-Ca- mena Fault (PCF) represents one of the most studi- ed tectonic features in the Romanian territory, even from the beginning of the 20th century [Mrazec, 1912; Macovei, 1912]. It generally appears (Fig. 1) as the boundary between the Moesian Platform (MP), re- presented in the area by Central Dobrogea (CD), and North Dobrogea (ND) geological units. During the time, PCF has been alternately con- sidered as a simple reverse fault [Macovei, 1912], or the over thrusting plan of the hypothetic Green Schists Nappe [Preda, 1964]. More recent research pointed out its strike-slip nature [Sandulescu, 1980; Gradinaru, 1984; Hippolyte et al.,1996; Besutiu, 1997; Banks, Robinson, 1997]. Geophysics brought significant evidence on the PCF in-depth extent. The international deep seis- mic soundings (DSS) line 0 2 [Radulescu et al., 1976] has revealed its crustal nature , showing a step of about 10 km at the both Conrad and Moho discontinuities. Later on, seismic tomography ima- ges based on CALIXTO experiment [Martin et al., 2006], have revealed PCF as a major lithospheric contact between East European Plate (EEP) and Moesian Micro-plate (MoP) reactivated during the W Black Sea opening [Besutiu, Zugravescu, 2004; Besutiu, 2009]. Geological evidence shows a PCF geodynamic evolution during the time with both right-lateral and left-lateral slip episodes [Pavelescu, Nitu, 1977; San- dulescu, 1980; Gradinaru, 1984; 1988; Seghedi, Oaie, 1995; Banks, Robinson, 1997; Cosma et al., 2010]. The Baspunar Geodynamic Observatory (BGD) was especially designed and run by the Solid Earth Dynamics Department at the Institute of Geody- namics of the Romanian Academy in order to moni- Fig. 1. Simplified tectonic setting of PCF and location of the study area: 1 — North Dobrogea boundaries (a — cropping out, b — covered); 2 — strike—slip faults; 3 — structural axes (a — syncline, b — anticline); 4 — boundaries between North Dobrogea main units (a — cropping out; b — buried); 5 — Cirjelari-Camena Outcrop Belt (a — cropping out, b — covered); 6 — episutural post-tectonic cover; 7 — river; 8 — settlements (a — major cities; b — villages); 9 — Baspunar Geodynamic Observatory (BGD) location; PDD — Predobro- gean Depression; ND — North Dobrogea; CD — Central Dobrogea; BB — Babadag Basin. �� !"#$ % &' () +' ,-&. &4 tor slip along PCF. This paper mainly deals with results of the high accuracy detailed magnetic in- vestigations carried out on the PCF segment loca- ted in the neighborhood of the BGD, aimed at re- vealing the path and in-depth structure of the PCF in the monitoring area. Research has been carried out in the frame of the bi-lateral project INRAF (“In- tegrated research of some active faults located in the NW inland of the Black Sea on the Romanian and Ukrainian territories”), jointly developed by the Institute of Geodynamics of the Romanian Acade- my and the Institute of Geophysics of the National Academy of Sciences of Ukraine. The local geological background. North Dobrogea. The area subject to geophysical inves- tigation mainly belongs to the so called Cirjelari-Ca- mena Outcrop Belt (CCOB). A thorough descripti- on of the structure and lithostratigraphy of this unit was provided by Gradinaru [Gradinaru 1980, 1984, 1988], and a simplified geological sketch for the stu- dy area is shown in Fig. 2, along with the location of the magnetically surveyed panels. On the overall, the study area is dominated by the presence of the Jurassic sedimentary and volcanic rocks, unconformable overlying older Palaeozoic de- posits of the Macin Unit and largely covered by the post-tectonic sedimentary cover of the Cretaceous Babadag Basin and shallow Quaternary formations. The Quaternary rocks are mainly represented by shallow layers of loess deposits. The Babadag Basin comprises two main Upper Cretaceous formations: Iancina and Dolosman se- Fig. 2. Simplified geologic sketch of the study area (modified after [Gradinaru, 1988]): 1 — Quaternary; 2 — Babadag basin, Episutural sedimentary cover; 3—9 — CCOB (3 — Baspunar Melange; 4 — Formation Sfanta (a), Amara Formation (b), 5 — Amara Breccia; 6 — Baspunar Spilite; 7 — Baspunar Formation; 8 — Camena Rhyolite; 9 — Aiorman Formation); 10—13 — Magin unit (10 — Uspenia Formation, 11 — Cirjelari Rhyolite, 12 — Camena Formation, 13 — Lower Paleozoic (marbles, quartzites and argillites)); 14—16 — Central Dobrogea (14 — Infragrauwacke, 15 — Lower Grauwacke, 16 — Upper Grauwacke), 17 — settlement; 18 — quarry; 19 — cross-section location; 20 — BGD; 21 — magnetic survey panel; 22 — PCF track (a — exposed, b — covered). ) /��' ) �0 1�2' ) 3 ��' �) 0� ��' ) ��' �) �2�0��2� &+ �� !"#$ % &' () +' ,-&. ries mainly consist of limestone and sandstone, with transient facia (between sandy limestone and limy sandstones). Overall, the Upper Cretaceous do- es not contain any source of geomagnetic anoma- lies, except for some residual red shale deposits, locally developed within confined volumes, but able to provide slight geomagnetic effects at the surfa- ce [Besutiu, Nicolescu, 1999]). Jurassic rocks of CCOB (Gradinaru, herein) may be grouped into several main sedimentary formati- ons (��): – Cirjelari �� (� 3 ox-km ) is composed of: 1) gaizes, spongolites, tuffittes, 2) polimictic conglomera- tes, 3) (marly and silty) shales, 4) bioclastic cal- carenites and calcirudites, 5) oolitic calcareni- tes. Also in the Cirjelari �� mixtites with Green Schist clasts, Cirjelari Rhyolite clasts, and oli- gomictic conglomerates may occur; – Baspunar �� (� 3 ox ) consists of: 1) gaizes, spon- golites, tuffittes, 2) crinoidal calcarenites, marl- stones, marly shales, 3) rhyolitic tuffs at the bottom; – Aiorman �� (� 2 ) is composed of terrigenous tur- bidites; – Movila Goala �� (� 2 ) consists of: 1) terrigeneous turbidites, 2) black oolitic calcarenites, 3) crino- idal calcarenites, bottomed by calcitized rhyo- lite lava flows. Another two special tectono-stra- tigraphic units should be also mentioned: the Amara breccia (� 3 ) and Baspunar Melange, with metabasic rocks, probably shared remnants of an incipiently developing oceanic crust in the fi- nal stage of CCOB [Gradinaru, 1984]; – the Amara Breccia (� 3 ox-km ) has been interpreted [Gradinaru, 1984] as a shared remnant of a for- mer more extensive talus breccias. It is a clast supported monomictic breccias consisting of ele- ments belonging to CD “Green Schist” series, and several levels of carbonates rocks from the Cirjelari ��, with a carbonate matrix; – the Baspunar Melange occurred later on (Late Jurassic), when the movement along PCF beca- me left-lateral. It contains blocks of Lower Pa- laeozoic marbles and quartzites of the Macin unit, but also blocks of Jurassic sedimentary and me- tabasic rocks. The Triassic deposits (Uspenia ��) mainly con- sist of gray limestone [Mirauta, Mirauta, 1961]. The Palaeozoic formations are practically hid- den by younger deposits, except for some confi- ned areas where they may crop out (Cirjelari valley, where Aiorman �� unconformable lies on Palaeo- zoic basement rocks). According to [Mirauta, Mirauta, 1961; Mirauta, 1966] the Palaeozoic deposits in the area mainly consist of Devonian (philite, limestone, serricite-chlo- rite schist), and Carboniferous, represented by Carape- lit �� (conglomerates, sandstones and schist series). The bimodal (acid and basic) CCOB volcanic rocks may be grouped into Camena Rhyolite (�� 3 ) and Baspunar spilite (� 3 ). The Camena Porphyries (� 3 ?) crop out between Cara Burun Hill (Camena) and Baspunar, and seem to be connected to the tectonic lineament Baspu- nar-Camena. They pierce the Proterozoic crystalli- ne series, but occur as remnants in the Liassic cong- lomerates. They have been described as micro-gra- nites accompanied by dykes [Mirauta, Mirauta, 1961], tuffs, ignimbrites and lava flows [Gradinaru, 1984]. The Baspunar spilite (�3) is mainly represented by pillow-lava flows interbeded in Jurassic limestone. Central Dobrogea (CD). South PCF, CD de- posits are mainly represented by the Upper Prote- rozoic Green Schist Series (GSS), largely descri- bed during the time by various authors [Mrazec, 1910, 1912; Macovei, 1912; Mirauta, Mirauta, 1961; Mirauta, 1964, 1965, 1969; Paraschiv, Paraschiv, 1978]. Mirauta describes several horizons of increas- ing (top to bottom) grade metamorphic rocks [Mira- uta, 1964]: 1) upper grauwacke (grauwacke , siliceous schists, micro-conglomerates); 2) lower grauwacke (grauwacke, schists); 3) infragrauwacke (green philites, green chlori- tic quartzites (meta-grauwacke). The infragrauwacke series are bottomed by so- me mezzo- to high-grade metamorphic rocks (mi- caschiste, quartzites, amphibolytes) occurring in the axis of the reverse mega-anticline structure Ceamu- rlia-Baspunar (Mirauta, herein). They are conside- red by various authors [Besutiu, 1997] as the source of the regional geomagnetic high overlying the axis of the Baspunar-Camena-Ceamurlia anticline. Since early times, it has been also noticed [Mo- tas, 1913] that CD deposits in the PCF contact zone are sometimes intercalated with, or intruded by mag- matic rocks of North Dobrogea (rhyolites), which might represent another source for geomagnetic anomalies. Data acquisition and processing. Field ob- servations were conducted by using two � 856 �� magnetometers (one for the record of diurnal geo- magnetic activity, and the second one for observa- tions along the survey lines). Basically, the survey lines were designed al- most perpendicular to the assumed PCF track. The lines are 4 m apart, and a step of 2 m between two consecutive stations along each line was used to survey the study area. Location of data points was set by using a Garmin 78 GPS receiver. The geo- graphic coordinates on WGS 1984 ellipsoid were then transferred into the rectangular coordinates PECENEAGA-CAMENA FAULT: GEOMAGNETIC INSIGHTS INTO ACTIVE TECTONIC CONTACT Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 36, 2014 137 Fig. 3. Residual geomagnetic anomaly along various PCF segments (a — micro-panel P1, b — micro-panels P3—P5) as obtained after removing a first order polynomial trend. Black dots mark data points. Brown solid lines show topography contours (in meters). Dashed zone marks the assumed PCF track. L. BESUTIU, M. ORLYUK, L. ZLAGNEAN, A. ROMENETS, L. ATANASIU, I. MAKARENKO 138 Ãåîôèçè÷åñêèé æóðíàë ¹ 1, Ò. 36, 2014 Fig. 5. Tentative interpretative model of the geomagnetic anomaly across PCF: 1 — residual geomagnetic anomaly, 2 — predicted field, 3 — body ID, 4 — magnetic susceptibility (in 10–6 CGSu); 5—13 — North Dobrogea (5 — loess, 6 — post-tectonic cover (K2), 7 — Upper Jurassic limestone, 8 — Lower Jurassic, 9 — Triassic limestone, 10 — Camena Fm (P2—T1), 11 — Baspunar spilite, 12 — Camena Porphyry, 13 — Cirjelari Rhyolite); 14—18 — Central Dobrogea (14 — diorite dykes, 15 — low-grade GSS, 16 — higher-grade GSS, 17 — secondary fault, 18 — breccias zone generated by fault dynamics). �� !"#$ % &' () +' ,-&. &5 of the Romanian national stereographic projection system [Avramiuc et al., 2001]. The geomagnetic sensor was placed at 3 m abo- ve the ground in order to avoid (or at least to miti- gate) shallow local effects. Diurnal geomagnetic activity was observed and recorded every minute during the survey in a local base-station, located close to the surveyed area. Routine processing has been applied to the raw observations in order to provide data consistency: removal of the effect of external sources and base reduction. As a result, a time-invariant Δ� as referred to the survey base-station was obtained. Finally, a residu- al geomagnetic anomaly was computed by remo- ving a first-order polynomial trend from the obser- vations, and Δ� a geomagnetic maps were plotted (Fig. 3). Modeling geomagnetic sources. Taking into consideration the pattern of the geomagnetic anomaly and some previous information on the stu- dy area, attempts for modeling the geomagnetic so- urces and their geological interpretation have been performed. The software. The professional GM-SYS® soft- ware run on the Geosoft OASIS® platform has been used for 2� modeling along the survey lines. It is based on the methods proposed by [Talwani et al., 1959; Talwani, Heirtzler, 1964], and employs algo- rithms published by [Won, Bevis, 1987]. Rocks magnetic properties. Magnetic pro- perties of the rocks in the area have been conside- red according to previous rock physics determina- tions [Besutiu, 1997; Besutiu, Nicolescu, 1999], to which additional determinations on outcrops samp- les were performed in the IG-NASU laboratory. Table 1 shows some magnetic properties of the main geological formations within North Dobrogea and the study area. Polarizing field. As Köenigsberger coefficient (�) of the geological formations known in the study area generally shows small values, the induced mag- netization model has been considered during the computation, with the following parameters for the polarising field: – total intensity field �� 48 500 nT, – geomagnetic inclination � �62° , – geomagnetic declination � �3° �. Physical model. Two main aspects of the mo- deling should be stressed: – to get a better fit between the observed and predicted anomaly, laterally extended geo- magnetic source models (exceeding the survey line) were taken into consideration; – due to the close vicinity of the survey lines, similar geomagnetic patterns, and, consequent- ly, except for small lateral changes in geomet- ry, rather similar models of the sources of the geomagnetic anomalies as showed in the follo- wings were outlined along various lines. Basically, following the trial & error process of 2� modeling along the survey lines the best fit has been obtained for the geometry and rock magnetic properties as illustrated in Fig. 4. Fig. 4. Physical model for the source of the residual geomagnetic anomaly along the line P: 1 — observed field, 2 — predicted effect, 3 — magnetic body ID (see Table 2). ) /��' ) �0 1�2' ) 3 ��' �) 0� ��' ) ��' �) �2�0��2� &.- �� !"#$ % &' () +' ,-&. �� ö �� Q� �� !�� "��#��$��%�#�� &�� '��' ��' (��)$��%�#�� &�� '� �� 67896:;9 <8=�8>6: ����+�� ,�� -!��-�� .�/��0�� -- %�� )�� .�/��12�.��%�� !��! �� 3��$��0�� -' �� /�3��$��%�� -�-' �� (��4� ��!' ��'� ��5�4�� '��-� ��' ��(�� '�� &�� 6�� '� �� &�� 1��,�� !�� 7��) ��)%�� '!�-�� 8�+��) �� !�� ! (��$��(�� '��!� �� (��96�� '�'� %��:�%��,��;49 �� ' �� &�� 9 �� ! �� /��: ��<�� )�� 4,�� '��'� �� =�� /�� '�! �� %%=& "��/)�� >,��$�4��/��<�� 4�� - %��?��Fm �� &��,��Fm ��- ��- 8��4��Fm �� %�4��/�� -�� &��,��,�� -�� %��?��/�� $/+�� %�� ,,��3) ��$� � ��3��+� ��-� �� 0��� ) ��$� � ��3��+� ��'-� �� !�� "��# � �� # �� $��"�%�� &��'( �� !"#$ % &' () +' ,-&. &.& (�&� ID � � �� )�� %�� &��,��,�� %�' �� &��,��,�� %�� &��,��,�� %�� &��,��,�� %�- �� &��,��,�� %�� &��,��,�� %�� &��,��,�� %�� %�4��/��@9&��,��,��@ %�! �� %�4��/��@9&��,��,��@ %�� A��$/��4��%��,��)�� <�� %�� %�4��Fm %�' ��-� %��?��/�� %�� 4��,��Fm %�� 9 ��&��,��4�� %�- �� ,��/�3��$ %�� ,��/�3��$ %�� �� %�� B��$�$��@9���� 3��+�@ %! �� B��$�$��@9���� 3��+�@ %� �� B��$�$��@9���� 3��+�@ %� �� 5� ��/�3��$�#����@9��@ %' ��'� B��$�$��@9���� 3��+�@ %� �� 0��� 3��+�� %� �� 0��� 3��+�� %- �� 0��� 3��+�� %� �� 7�3�� 3��+� %� �� 7�3�� 3��+� Overall, to predict the geomagnetic anomaly, several 2� magnetic bodies have been considered. Table 2 shows their magnetic susceptibilities along with the assumed geological significance. Geological interpretation. Based on previ- ously gathered tectonic knowledge and rock phy- sics of the main geological formations occurring in the study area and neighbouring region, an attempt for interpreting the geomagnetic sources outlined by modeling has been made. The results are syntheti- cally illustrated in Fig. 5. As previously mentioned, the interpretative geological cross-section lateral- ly extends over the magnetic line in order to miti- gate the effect of the signal truncation and side effects. Overall, the geological interpretation of the syn- thetic model has allowed outlining the PCF path by separating PCF flanks due to the general dis- tinct geomagnetic behaviour of their different em- bedded geological formations (basically magnetic CD Proterozoic GSS versus non-magnetic ND Pa- laeozoic sedimentary). But, the survey accuracy has also allowed dis- criminating some distinct layers with different mag- netization within GSS, as well as the presence of some intrusive rocks (diorite dykes?) penetrating the geological formations. On the other hand, basalt flows (Ba�punar spi- lite) embedded within the Ba�punar �� (Jurassic and/or Triassic limestone) significantly complicate � ��� !�� "�� #�&�� ) /��' ) �0 1�2' ) 3 ��' �) 0� ��' ) ��' �) �2�0��2� &., �� !"#$ % &' () +' ,-&. the interpretation by locally increasing the geomag- netic behaviour of the respective sedimentary pile. Revealing the PCF track. Taking into consi- deration the peculiarities of the geomagnetic field pattern over the two flanks of the PCF, and the re- sults of the quantitative interpretation of the 2� mo- deling along the survey lines, PCF track could be clearly outlined in the areas covered by recent depo- sits except for some confined areas due to the insuf- ficient westward extension of the survey lines Fig. 6. Geodynamic considerations. One interest- ing aspect pointed out by the geomagnetic mode- ling has been the apparent lack of magnetic proper- ties in the central compartment of the interpreta- tive cross-section, located along the assumed PCF track. This has been interpreted in terms of fragmen- tation of the PCF flanks, generating rock-debris thro- ugh the abrasion of the fault flanks as a consequ- ence of its active slip. Despite some initial indivi- dual magnetic properties, on the overall, elements of this compartment may not be reflected in the pat- tern of the geomagnetic anomaly due to the cur- rent of randomly distributed direction of magneti- zation of the breccias elements. Besides, water cir- culating within the contact zone accelerated the magnetic minerals weathering and, consequently, the loss/mitigation of original magnetic properties. Fig. 6. PCF imprint in the pattern of the residual geomagnetic anomaly along various survey lines. 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Geomagnetic insights on an active tectonic contact: Peceneaga-Camena Fault

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