Geologica Acta: an international earth science journal ISSN: 1695-6133 [email protected] Universitat de Barcelona España
DICLE, S.; ÜNER, S. New active faults on Eurasian-Arabian collision zone: Tectonic activity of Özyurt and Gülsünler faults (eastern Anatolian Plateau, Van-Turkey) Geologica Acta: an international earth science journal, vol. 15, núm. 2, junio, 2017, pp. 107-120 Universitat de Barcelona Barcelona, España
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S. Dúcle, S. Üner, 2017 CC BY-SA New active faults on Eurasian-Arabian collision zone: Tectonic activity of Özyurt and Gülsünler faults (eastern Anatolian Plateau, Van-Turkey)
S. DúCLE1 and S. ÜNER2*
1Yüzüncü Yıl University, Institute of Science Zeve Campus, 65080, Van-Turkey. E-mail: [email protected]
2Yüzüncü Yıl University, Department of Geological Engineering Zeve Campus, 65080, Van-Turkey. E-mail: [email protected]
*Corresponding author
ABSTRACT The Eastern Anatolian Plateau emerges from the continental collision between Arabian and Eurasian plates where intense seismicity related to the ongoing convergence characterizes the southern part of the plateau. Active deformation in this zone is shared by mainly thrust and strike-slip faults. The Özyurt thrust fault and the Gülsünler sinistral strike-slip fault are newly determined fault zones, located to the north of Van city centre. Different types of faults such as thrust, normal and strike-slip faults are observed on the quarry wall excavated in Quaternary ODFXVWULQHGHSRVLWVDWWKHLQWHUVHFWLRQ]RQHRIWKHVHWZRIDXOWV.LQHPDWLFDQDO\VLVRIIDXOWVOLSGDWDKDVUHYHDOHG coeval activities of transtensional and compressional structures for the Lake Van Basin. Seismological and geomorphological characteristics of these faults demonstrate the capability of devastating earthquakes for the area.
KEYWORDS Lake Van Basin. Eastern Anatolia Plateau. Compressional tectonics. Kinematic analysis. Quaternary faults.
INTRODUCTION Ongoing continental collision between the northward moving Arabian and quasi-stationary Eurasian plates gave Continental collision zones are sites of intense crustal rise to the formation of the Eastern Anatolian Plateau (EAP) deformation resulting in different geological processes VLQFH 0LGGOH 0LRFHQH ûHQJ|U DQG .LGG ûHQJ|U such as crustal thickening, regional contraction, and DQG<×OPD] 'HZH\ et al. .HVNLQ et al. , 1998) volcanic activity. These zones present a complex tectonism (Fig. 1A). The southern part of the EAP is a key region for commonly including thrusts and folds, and other structural understanding the tectonic activity and related deformation elements such as strike-slip faults (Sylvester, 1988; Mann, pattern of this collision zone where numerous researchers 2007; Dooley and Schreurs, 2012). Studies of the later have focused since the 1980’s. These studies indicate that are much less common in those contexts. The Himalayan major structures related to this tectonic activity are NE- collision zones are well-known examples of this tectonism striking sinistral, NW-striking dextral strike-slip faults and (Zhao et al. , 2010). coeval E–W-trending reverse and N–S-trending normal
107 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults
25 35 43 00 43 50 Çaldiran Fault Black Sea EURASIAN PLATE Eastern Anatolia Plateau NAFZ study 40 ANATOLIA area EAFZ Bitlis-Zagros Suture Erciş Fault
Erciş 39 00 35 ARABIAN Cyprean Arc DSFZ PLATE Aegean Arc Muradiye Mediterranean Sea
0 200 400 km 30 AFRICAN PLATE A
Karasu R. Özyurt Fault Ahlat Karasu Fault Ağarti Fault Nemrut Alaköy Fault Lake Volcano Alaköy Fault Erçek LAKE VAN Gülsünler Fault Çarpanak Fault Everek Fault
Alabayir Fault
Tatvan Figure 3 38 50 VAN
NAFZ North Anatolian Fault Zone EAFZ East Anatolian Fault Zone DSFZ Dead Sea Fault Zone
Strike slip fault Gürpinar Fault Thrust fault Gevaş Gürpınar City centre / town N 0 10 20 30 km B
FIGURE 1. A) Major neotectonic features of Turkey and adjacent areas (white arrows indicate the motion of the plates), B) location map showing active faults on eastern part of Lake Van Basin.
faults. (Dewey et al. ûDURùOX DQG <×OPD] et al. , 2001; Özkaymak et al. .Ro\LùLW <×OPD] et al. .Ro\LùLW et al. , 2001; Özkaymak et al. , Mackenzie et al. , 2016). 'RùDQDQG.DUDNDü .Ro\LùLW 2NXOGDü DQGhQHU The Özyurt fault and Gülsünler fault are two active IDXOWVORFDWHGHDVWRIWKH/DNH9DQ%DVLQWKDWDUHGHÀQHG Numerous basins appear related to this compressional IRUWKHÀUVWWLPHLQWKLVSDSHU7KH\H[WHQGIURPQRUWKRI WHFWRQLVP VXFK DV WKH 3DVLQOHU 0Xü DQG /DNH 9DQ the Van metropolis to the centre of the basin (Fig. 1B). EDVLQV ûDURùOXDQG*QHU 7KH/DNH9DQ%DVLQ The aims of this paper are to analyse these two faults is located at the southern part of the EAP. It formed in and to discuss their interaction with morphological and the Late Pliocene and was shaped by the volcanism that palaeoseismological data. was active during the Quaternary (Degens et al. , 1984). The basin contains the largest sodic lake in the world (Lake Van) which was formed approximately 600kyr REGIONAL GEOLOGY ago (Stockhecke et al. , 2014). East of this depression there are several active faults ( e.g. (YHUHN $ODN|\ The northward motion of the Arabian plate with respect dDOG×UDQDQG*US×QDUIDXOWV )LJ% WKDWJHQHUDWH to the Eurasian plate caused crustal shortening, thickening, GHQVHVHLVPLFLW\ ûDURùOXDQG<×OPD] .Ro\LùLW DQGXSOLIWRIWKH($3VLQFH0LGGOH0LRFHQHWLPHV ûHQJ|U
Geologica Acta, 15(2), 107-120 (2017) 108 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults
DQG .LGG <×OPD] et al. , 2010). Deformation was Basin sediments dominated by approximately E–W-trending thrust faults ûDURùOXDQG<×OPD] .Ro\LùLW ,QWKLVSHULRG Basement units are unconformably overlain by Pliocene WKHSODWHDXZDVUDLVHGDERXWNP .Ro\LùLW et al. , 2001) ÁXYLDO GHSRVLWV 4XDWHUQDU\ YROFDQLFV DQG ODFXVWULQH and the compressional basins, such as the Lake Van Basin sediments younger than 600kyr (Stockhecke et al. , 2014). ZHUH IRUPHG ûDURùOX DQG *QHU 3URJUHVVLYH 7KHEDVLQLQÀOOHQGVZLWK/DWH4XDWHUQDU\WUDYHUWLQHDQG contraction caused the westward escape of the Anatolian UHFHQW XQFRQVROLGDWHG ÁXYLDO VHGLPHQWV $FDUODU et al. , plate along the North and East Anatolian fault Systems ûHQHO )LJ GXULQJWKH/DWH3OLRFHQH ûHQJ|U et al. , 1985) (Fig. 1A). The strike-slip faulting dominated neotectonic deformation The Pliocene fluvial deposits include red LQ WKH ($3 .Ro\LùLW et al. , 2001). NW-trending dextral conglomerates-sandstones and mudstones. These units IDXOWV dDOG×UDQ(UFLüDQG$ODED\×UIDXOWV 1(WUHQGLQJ are unconformably overlain by Quaternary lacustrine VLQLVWUDOVWULNHVOLSIDXOW .DUDVXIDXOW DQG(²:WUHQGLQJ deposits which are thin- to medium-bedded semi- WKUXVW IDXOWV $ùDUW× $ODN|\ (YHUHN dDUSDQDN DQG consolidated gravel-sand-mud alternations. Thin- *US×QDU IDXOWV DUH WKH PDMRU VWUXFWXUHV RI WKH UHJLRQ bedded, clayey deep water lacustrine deposits and sand- ûDURùOX DQG <×OPD] .Ro\LùLW et al. , 2001; gravel rich shallow water and lake shore deposits are Özkaymak et al. .Ro\LùLW )LJ% 7KHVH frequently observed along the eastern side of the Lake very close thrust faults are interpreted as splays from the Van. Pelecipoda (Dreissena sp.) rich, shore deposits are main detachment surface (Özkaymak et al. , 2011). N–S- eroded by deltaic or fluvial sediments in many places trending normal faults are rarely observed in the area. due to water level oscillations. Alternation of lacustrine deposits with fluvial sediments suggests large scale The volcanic centers Nemrut, Süphan, Tendürek, and fluctuations in the shoreline of the Lake Van. $ùU× $UDUDW ZHUH GHYHORSHG RQ WKH SODWHDX GXULQJ WKH neotectonic period in Quaternary. Most of the plateau is Volcanic rocks are commonly observed at the northern FRYHUHGE\WKHSURGXFWVRIWKLVYROFDQLVP <×OPD] et al. , DQGQRUWKZHVWHUQSDUWVRIWKH/DNH9DQ%DVLQ )LJ 7KH\ .HVNLQ et al. , 1998; Aydar et al. .DUDRùOX et include basalts and pyroclastics, derived from Nemrut al. , 2005; Özdemir et al. ZKLOHRWKHUDUHDVDUHÀOOHG and Süphan volcanoes. Pyroclastic layers alternate with ZLWKODFXVWULQHDQGÁXYLDOGHSRVLWV lacustrine deposits due to the activities of these volcanoes.
Age Litology Explanation STRATIGRAPHY Alluvial deposits Hol . Unconformity Travertines In this study, Miocene and older units that are Unconformity Lacustrine deposits unconformable onto Mesozoic and older rock units are Unconsolidated sand, silt considered as basement while younger sedimentary and clay with tu" layers
Quaternary Basalt, dacite and andesite
VHTXHQFHV FRUUHVSRQG WR WKH EDVLQ ÀOO UHODWHG WR WKH Pleistocene from Nemrut and Süphan evolution of Lake Van Basin (Fig. 2). volcanoes
Unconformity
Basement units BASIN INFILL Fluvial deposits (conglomerates and sandstones) The oldest basement units are the Bitlis metamorphic Pliocene Unconformity rocks, at the southern part of the basin, outside of the Turbidite deposits (sandstone study area. They mainly consist of Palaeozoic–Mesozoic Tertiary and mudstone alternation with
Miocene JQHLVVHVPHWDEDVLFURFNVDQGVFKLVWV 2EHUKlQVO× et al. , gravel layers)
<×OPD] et al. , 2010). Jurassic limestones, Upper Oligocene - Cretaceous ophiolitic rocks (Yüksekova mélange) and Unconformity Oligocene-Miocene turbidites are found to the east of the Upper Ophiolitic Mélange Cretaceous Serpentinite, radiolarite and basin (Acarlar et al. ûHQHO )LJ 2SKLROLWLF gabbro URFNVLQFOXGLQJPDÀFXOWUDPDÀFWHFWRQLWHVDQGFXPXODWHV are related to the evolution of the Neotethian Ocean during Crystallized dolomitic limestones
Jurassic WKH &UHWDFHRXV <×OPD] DQG <×OPD] 6KDOORZ WR Unconformity BASEMENT UNITS deep marine turbidites formed by sandstone-mudstone pre- Metamorphic rocks (Gneisses, Jurassic meta-basic rocks, schists) alternation with gravelly layers deposited during the Not to scale closure period of this ocean from Oligocene to Miocene FIGURE 2. Tectono-stratigraphic chart of the study area (modified times (Acarlar et al. , 1991). from Acarlar et al., 1991; ûenel, 2008).
Geologica Acta, 15(2), 107-120 (2017) 109 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults
N 43.10 43.20 43.30 43.40 43.50 Yeşilsu Pirgarip Tabanlı Dağönü
Özyurt
Güvençli Karasu Fault
Karasu River Pirgarip segment Ö z y u r t T h r u s t F a u lt Hıdırköy
LAKE Göllü 38.70 Adıgüzel Ağarti Ağartı Foult VA N Otluca LAKE Yumrutepe Alaköy Alaköy Fault Kasımoğlu ERÇEK
Alaköy Fault Gülsünler
Karasu River Gülsünler Fault Alluvium
Yeşilköy
Quaternary units Çarpanak Fault Yeşilköy segment 38.60 Çitören lacustrine deposits
Neotectonic Çarpanak island Alabayır Fault Pliocene 'uvial deposits
Everek Fault Alabayır Oligocene - Miocene turbidite deposits Settlement Quarry site Upper Createcous
units Morali River ophiolites Strike-slip fault
Palaeotectonic Thrust fault 0 2 4 6 km Jurassic limestones VAN
FIGURE 3. Geological map of the study area (modified from Acarlar et al., 1991; ûenel, 2008).
Quaternary travertines and recent alluvial deposits are the extension (0.25 Structural data, such as strike, dip, and slip-lineation Özyurt thrust fault measurements were collected from fault planes for determination of different deformation phases. Most Özyurt fault is a 19km long, E-W trending reverse fault of the data were obtained from gravel, sand, and silt- WKDWUXQVEHWZHHQg]\XUWYLOODJHWRWKHZHVWDQG+×G×UN|\ sized, semi-consolidated lacustrine deposits. Timing of YLOODJHWRWKHHDVW )LJ 7KHVRXWKHUO\GLSSLQJHDVWHUQ faulting and deformation are distinguished by the age VHFWLRQRIWKHIDXOWQRUWKRI+×G×UN|\LVWKHERXQGDU\ of the stratigraphic units and cross-cutting relationships. between the Oligocene-Miocene turbidites and the Upper Cretaceous ophiolitic mélange units (Fig. 4A). Damian Delvaux’s Tensor software (Win-Tensor 4.0.4) was used to analyze fault-slip data (Delvaux and The western part of the Özyurt fault bifurcates into 6SHUQHU )RU WKH GHÀQLWLRQ RI WKH SDOHRVWUHVV QRUWKDQGVRXWKEUDQFKHVWRWKHZHVWRI*YHQoOLYLOODJH ÀHOGWKHQDWXUHRIWKHYHUWLFDOVXEYHUWLFDOVWUHVV D[LV Southerly-dipping northern branch is 5km long which and the value of ratio R were taken into calculations. juxtaposes the Upper Cretaceous ophiolitic mélange 6WUHVV ÀHOGV PD\ YDU\ IURP UDGLDO H[WHQVLRQ Ʊ units and Jurassic limestones (Fig. 4B-C). Northerly- YHUWLFDO 5 H[WHQVLRQ ƱYHUWLFDO ZLWKSXUH dipping southern branch is 6km long which separates Geologica Acta, 15(2), 107-120 (2017) 110 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults N Upper Cretaceous Ophiolitic Mélange Oligocene-Miocene Turbidites ÖZYURT FAULT A N serpentinites Jurassic Limestones C Upper Cretaceous BB Ophiolitic Mélange CC N LAKE VAN Springs Upper Cretaceous Ophiolitic Mélange D Jurassic D ÖZYURT FAULTLimestones FIGURE 4. Field photographs showing the Özyurt thrust fault; A) eastern part of the fault between Oligocene-Miocene turbidites and Upper Cretaceous ophiolitic mélange, B) northern branch of the western part of the fault, C) close-up view of the serpentinites from ophiolitic mélange and D) springs on southern branch of western part of the fault. Geologica Acta, 15(2), 107-120 (2017) 111 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults WKHVDPHXQLWV )LJ 6RXWKHUQEUDQFKFDQFOHDUO\EH regional neotectonic activity is analysed. Only at one followed by lithological borders and the alignment of location the fault plane, cutting the Quaternary shore water springs (Fig. 4D). The connection of the southern deposits of Lake Van, was evaluated (Fig. 6). branch with eastern part of the Özyurt thrust fault is a NE–SW trending sinistral strike-slip fault near the The result of the analysis indicates a N–S compressional *YHQoOLYLOODJH )LJ 7KHVRXWKHUQEUDQFKGHIRUPV VWUHVVUHJLPH )LJ& $WWKLVORFDWLRQWKHƱLVYHUWLFDO the semi-consolidated, gravelly shore deposits of the and according to value of ratio (R= 0.5), the type of Lake Van (Fig. 6A). Movement of the fault blocks deformation is pure compression (Delvaux et al. , 1997). caused re-orientation of pebbles along longitudinal axes in the fault zone (Fig. 6B). Prolongation of the branches Gülsünler fault cannot be observed to the west as the faults enter the Lake Van. The 20km long Gülsünler fault is exposed between WKH 3LUJDULS DQG N B A C B FIGURE 5. Field photograph of the eastern connection of the Özyurt thrust fault that has strike-slip character; A) vertical fault plane on Jurassic limestones, B) close-up view of fault plane and striations and C) plot of the fault plane (modified from Van der Pluijm and Marshak, 2004). Geologica Acta, 15(2), 107-120 (2017) 112 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults 075º/68º NW B B 1 22/357 N 2 14/26 1 3 64/141 R : 0,5 thrust fault A C FIGURE 6. A) Field photograph showing the Özyurt fault in gravelly shore deposits of Lake Van, B) close-up view of fault zone (gravel orientations showing the direction of movement) and C) result of the palaeostress analysis on Schmidt lower hemisphere. Alignment of the water springs and shifted drainage pattern Horizontally bedded deposits consist of semi-consolidated, are the morphological features of this zone (Fig. 7B-C). VWUDWLÀHGVDQGVDQGWKLQEHGGHGFOD\DOWHUQDWLRQV2QHSDUW %HQGLQJ]RQHVRIWKH.DUDVXULYHUFKDQQHODQGWKH$ODN|\ of the quarry has 8 faults in the same wall (Fig. 8A). All WKUXVWIDXOWLVORFDWHGRQWKH Geologica Acta, 15(2), 107-120 (2017) 113 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults W E 050º/74ºNW (rake: 14ºS) Sinistral strike-slip fault with apparent normal component A N S B Yeşilköy segment C FIGURE 7. A) Field photograph showing the Quaternary fluvial and lacustrine deposits deformed by Ye üilköy segment of the Gülsünler fault. B) Photograph and C) line drawing of shifted drainage patterns on Yeüilköy segment (northeast of Yeüilköy village). Geologica Acta, 15(2), 107-120 (2017) 114 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults S N 9 8 7 6 2 3 4 5 AA E W W E tilted delta-front deposits 13 12 10 11 B CC FIGURE 8. Photo showing the structural elements of Otluca quarry; A) faults on north wall of the quarry, B) a normal and three reverse faults on west wall of the quarry and C) tilted delta front deposits. Fault-slip analysis of Gülsünler fault the type of deformation is transtensional (Delvaux et al. , )LJ & 7KLUGGDWDVHW )LJ $ Results of the analysis indicate three different from Otluca quarry refers to NE–SW compressional stress deformation mechanisms. First data measured from UHJLPH$W WKLV ORFDWLRQWKHƱ LV YHUWLFDODQG DFFRUGLQJ 6HFRQGGDWDVHW )LJ $ SLFNHG The Lake Van Basin is located on one of the most from Otluca quarry is characterized by NE-SW tensional seismically active regions of Turkey. It experienced several stress regime. At the same location, none of the principle destructive earthquakes in the historical and instrumental stress axes are vertical. According to R values (R=0.78), SHULRG 3×QDUDQG/DKQ (UJLQ et al. , 1967; Soysal et Geologica Acta, 15(2), 107-120 (2017) 115 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults principle stress value of location nº strike & dip rake sense axis ratio (R) UHJLRQZHUHdDOG×UDQ(DUWKTXDNH 0Z DQG9DQ7DEDQ 1 = 20/203 (DUWKTXDNH 0Z dDOG×UDQ (DUWKTXDNH 1RYHPEHU Yeşilköy 1 050/74N 14S Sinistral 2 = 69/002 0,5 24th, 1976) was caused by the NW trending, dextral strike- segment 3 = 07/111 VOLS IDXOW ZLWK ODUJH DPRXQW RI FDVXDOWLHV SHRSOH 2 125/89N 01W Sinistral 4 150/85E 01W Sinistral DQGGDPDJHLQdDOG×UDQWRZQDQGFORVHUDUHD (\LGRùDQ 5 135/59S 89S Normal 1 = 23/293 6 124/89N 01W Sinistral et al. , 1991). 2 = 67/117 0,78 7 130/86N 01W Sinistral Otluca 8 146/87E 01W Sinistral 3 = 01/024 quarry 9 140/43W 89W Normal 13 160/26W 89W Normal 9DQ7DEDQO× (DUWKTXDNH 2FWREHU UG LV WKH largest seismic event originated from a thrust fault in 3 137/71W 89S Reverse 1 = 30/227 10 140/48W 89S Reverse 7XUNH\ .Ro\LùLW 7KHHSLFHQWUHRIWKHHDUWKTXDNH 11 130/62S 89S Reverse 2 = 01/317 0,5 12 142/59W 89S Reverse 3 = 60/048 was located about 25km northeast of Van city centre. It 23/293 N N 1 20/203 N 1 1 30/227 caused 604 death and damage. Thousands of aftershocks 2 67/117 2 69/002 2 01/317 occurred within a closer area. 3 07/111 3 01/024 3 60/048 R : 0,5 R : 0,78 R : 0,5 Nr : 1 Nr : 8 Nr : 4 Recent activities of new detected Özyurt and Gülsünler faults are determined by the seismological records of FIGURE 9. A) Fault-plane measurements on Ye ilköy segment and the WKH 1DWLRQDO (DUWKTXDNH 0RQLWRULQJ &HQWHU RI .DQGLOOL north and west walls of the Otluca quarry. Results of the palaeostress 2EVHUYDWRU\ DQG (DUWKTXDNH 5HVHDUFK ,QVWLWXWH.2(5, analysis of striated fault planes with indications on Schmidt lower hemisphere; B) pure strike-slip stress regime, C) NE-SW tensional .2(5, (SLFHQWUHVRIHDUWKTXDNHVUDQJLQJIURP stress regime and D) NE-SW compressional stress regime. to 6 magnitudes (in 2011-2015 period) that match with the faults evidence the seismic activity of these faults in recent times (Figs. 10; 11). al. , 1981; Ambraseys, 1988; Ambraseys and Finkel, 1995; Tan et al. 6HOoXN et al. , 2010; Utkucu et al. 7KH HSLFHQWUHV RI GLYHUVHVL]HG HDUWKTXDNHV DUH The most destructive earthquakes occurred in Lake Van ORFDWHGRQWKHg]\XUWWKUXVWIDXOW .2(5, )LJ 43.20 N 43.30 43.40 LAKE Şahgeldi Yeşilsu VAN Tabanlı Pirgarip Dağönü 38.75 Özyurt Güvençli Hıdırköy Karakeçe Hill Göllü Ağarti Otluca Epicentre 3.0 M 4.0 Settlement 38.70 Epicentre 4.0 M 5.0 Earthquake focal mechanism Epicentre 5.0 M 6.0 solution 1 2 3km FIGURE 10. Earthquake records (M ≥3.0) in instrumental period near the Özyurt fault (yellow circles showing earthquakes on the fault while white ones showing others) (KOERI, 2016). Geologica Acta, 15(2), 107-120 (2017) 116 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults LAKE VAN 43.30 43.35 43.40 N Yeşilsu Pirgarip Tabanlı 38.75 Ocaklı Pirgarip Segment Güvençli Karakeçe Hıdırköy Hill Göllü Otluca quarry 38.70 Otluca Kasımoğlu Gülsünler Yumrutepe Özkaynak Yeniköşk 0 1 2 3km 38.65 Settlement Quarry site Earthquake focal Yeşilköy Segment mechanismsolution Epicentre 3.0 M 4 Yeşilköy Epicentre 4.0 M 5 FIGURE 11. Earthquake records (M ≥3.0) in instrumental period near the Gülsünler fault (yellow circles showing earthquakes on the fault while white ones showing others) (KOERI, 2016). The distribution of these epicentres is compatible with the 2FWREHU UG 9DQ7DEDQO× (DUWKTXDNH WKH VWXGLHV branched structure of the Özyurt thrust fault in the west. about seismicity of the region increased (Özkaymak et al. , Earthquake focal mechanism solutions on Özyurt thrust $OW×QHU et al. 'L 6DUQR et al. 'RùDQ fault taken from previous studies (AFAD, 2011; Irmak et DQG.DUDNDü )LHOGLQJ et al. .Ro\LùLW al. , 2012) show the approximately E–W trending reverse Utkucu et al. dXNXUet al. , 2016). IDXOWDFWLYLW\ )LJ 7KHHSLFHQWUHVRI HDUWKTXDNHV FRLQFLGHRQWKH*OVQOHUIDXOW .2(5, )LJ Newly mapped Özyurt and Gülsünler faults provide The distribution of these epicentres is coherent with the important clues for understanding the neotectonic regime step-over morphology of Gülsünler fault. Earthquake in the east of Lake Van and the northern part of Arabian focal mechanism solutions on Gülsünler fault taken from and Eurasian collision zone. Geological properties and previous studies (AFAD, 2011; Irmak et al. , 2012) show recent activities of these faults are determined on the basis the approximately NE–SW trending sinistral strike-slip RIÀHOGVWXGLHVDQGVHLVPLFUHFRUGV7KHWUDFHVRIIDXOWV fault activity (Fig. 11). observed in Quaternary semi-consolidated lacustrine and shore deposits of Lake Van are the main indication of this activity. DISCUSSION AND CONCLUSIONS The eastern segment of the Özyurt thrust fault, north of The southern part of the Eastern Anatolian Plateau is +×G×UN|\LQFOXGHVVRXWKHUO\GLSSLQJIDXOWSODQHVXQOLNHWR less studied area than the other regions of Turkey. After WKH,O×ND\QDNWKUXVWIDXOW .Ro\LùLW $QGZHIRXQG Geologica Acta, 15(2), 107-120 (2017) 117 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults QRÀHOGRUVHLVPLFHYLGHQFHRIDGLUHFWFRQQHFWLRQEHWZHHQ REFERENCES the two thrust faults. $FDUODU0%LOJLQ$=(OLERO((UNDQ7*HGLNú*QHU Gülsünler fault is another structure introduced for (+DN\HPH]<ûHQ$08ùX]0)8PXW0 WKHÀUVWWLPHLQWKLVSDSHU1(WUHQGLQJVLQLVWUDOVWULNH Geology of the eastern and northern part of Lake Van. The slip fault is determined with the help of lineaments, Mineral Research and Exploration Institute of Turkey (MTA) displacement of lithologies, and shifting of stream Technical Report Nr. 9469. channels. The fault is divided in two segments, Pirgarip AFAD, 2011. Prime Ministry Disaster and Emergency DQG Geologica Acta, 15(2), 107-120 (2017) 118 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults 'RùDQ%.DUDNDü$*HRPHWU\RIFRVHLVPLFVXUIDFH of the eastern Bitlis complex, SE Turkey. In: Sosson, UXSWXUHVDQGWHFWRQLFPHDQLQJRIWKH2FWREHU0Z 0 .D\PDNFL 1 6WHSKHQVRQ 5$ %HUJHUDW ) 7.1 Van earthquake (East Anatolian Region, Turkey). Journal Starostenko, V. (eds). Sedimentary Basin Tectonics from of Structural Geology, 46, 99-114. the Black Sea and Caucasus to the Arabian Platform. Dooley, T.P., Schreurs, G., 2012. Analogue modelling of intraplate /RQGRQ*HRORJLFDO6RFLHW\ 6SHFLDO3XEOLFDWLRQV strike-slip tectonics: A review and new experimental results. Tectonophysics, 574-575, 1-71. 2NXOGDü & hQHU 6 *HRPRUSKRORJLFDO 3URSHUWLHV DQG (UJLQ.*oO88]= (DUWKTXDNH&DWDORJIRU7XUNH\ 7HFWRQLF$FWLYLW\RI$ODN|\)DXOW /DNH9DQ%DVLQ²(DVWHUQ DQG VXUURXQGLQJ DUHD $' úVWDQEXO 7HFKQLFDO $QDWROLD %XOOHWLQIRU(DUWK6FLHQFHV University, Geophysical Institute Publications, 28, 169pp. g]GHPLU < .DUDRùOX g 7ROOXRùOX $h *OHoÞ 1 (\LGRùDQ+8WNX=*oO8'HùLUPHQFL( 6HLVPLF Volcanostratigraphy and petrogenesis of the Nemrut *XLGHRI0DMRU(DUWKTXDNHVRI7XUNH\ úVWDQEXO stratovolcano (East Anatolian High Plateau): The most recent 8QLYHUVLW\úVWDQEXO'HSDUWPHQWRI*HRSK\VLFDO(QJLQHHULQJ post-collisional volcanism in Turkey. Chemical Geology, Publications, 198pp. 226, 189-211. Fielding, E.J., Lundgren, P.R., Taymaz, T., Yolsal-Çevikbilen, g]ND\PDN d 6|]ELOLU + %R]NXUW ( 'LULN . 7RSDO 7 62ZHQ6()DXOW6OLS6RXUFH0RGHOVIRUWKH $ODQ + dDùODQ ' 6HLVPLF *HRPRUSKRORJ\ RI Mw 7.1 Van Earthquake in Turkey from SAR Interferometry, 2FWREHU 7DEDQO×9DQ(DUWKTXDNH DQG ,WV 5HODWLRQ Pixel Offset Tracking, GPS, and Seismic Waveform Analysis. to Active Tectonics of East Anatolia. Journal of Geological 6HLVPRORJLFDO5HVHDUFK/HWWHUV (QJLQHHULQJ ,UPDN76 'RùDQ % .DUDNDü$ 6RXUFH PHFKDQLVP 3×QDU 1 /DKQ ( 7XUNLVK (DUWKTXDNH &DWDORJ ZLWK RIWKH2FWREHU9DQ 7XUNH\ HDUWKTXDNH 0Z Discriptions. Technical Report, Turkey. The Ministry of and aftershocks with its tectonic implications. Earth Planets Public Works and Settlement. The General Directorate of 6SDFH &RQVWUXFWLRQ$IIDLUV6HULDOSS .DUDRùOX g g]GHPLU < 7ROOXRùOX $h .DUDE×\×NRùOX 6HOoXN / 6DùODP 6HOoXN $ %H\D] 7 3UREDELOLVWLF 0 .|VH 2 )URJHU -) 6WUDWLJUDSK\ RI WKH seismic hazard assessment for Lake Van basin, Turkey. volcanic products around Nemrut Caldera: implications for Natural Hazards, 54, 949-965. reconstruction of the caldera formation. Turkish Journal of 6R\VDO + 6LSDKLRùOX 6 .ROoDN ' $OW×QRN < (DUWK6FLHQFHV Earthquake Catalog for Turkey and surrounding area (2100 .HVNLQ 0 3HDUFH -$ 0LWFKHOO -* 9ROFDQR %&² $' 7KH6FLHQWLÀFDQG7HFKQRORJLFDO5HVHDUFK stratigraphy and geochemistry of collision-related volcanism &RXQFLORI7XUNH\5HSRUW1U 7%$*SS RQWKH(U]XUXP.DUV3ODWHDX1RUWK(DVWHUQ7XUNH\-RXUQDO 6WRFNKHFNH 0 .ZLHFLHQ 2 9LJOLRWWL / $QVHOPHWWL )6 RI9ROFDQRORJ\DQG*HRWKHUPDO5HVHDUFK %HHU-dDùDWD\01&KDQQHOO-(7.LSIHU5/DFKQHU .Ro\LùLW$1HZÀHOGDQGVHLVPLFGDWDDERXWWKHLQWUDSODWH J., Litt, T., Pickarski, N., Sturm, M., 2014. Chronostratigraphy strike-slip deformation in Van region, East Anatolian plateau, of the 600,000 year old continental record of Lake Van E. Turkey, Journal of Asian Earth Sciences, 62, 586-605. (Turkey). Quaternary Science Reviews, 104, 8-17. .Ro\LùLW $ <×OPD] $ $GDPLD 6 .XORVKYLOL 6 Sylvester, A.G., 1988. Strike-slip faults. Geological Society of Neotectonic of East Anatolian Plateau (Turkey) and Lesser $PHULFD%XOOHWLQ Caucasus: implication for transition from thrusting to strike- ûDURùOX ) *QHU < 7KH DFWLYH 7XWDN IDXOW LWV slip faulting. Geodinamica Acta, 14, 177-195. FKDUDFWHULVWLFVDQGUHODWLRQVWRWKHdDOG×UDQ)DXOW Geologica Acta, 15(2), 107-120 (2017) 119 DOI: 10.1344/GeologicaActa2017.15.2.3 S . D úcle and S. Üner Tectonic activity of Özyurt and Gülsünler faults ûHQJ|U$0&<×OPD]< 7HWK\DQHYROXWLRQRI7XUNH\ D <×OPD]$<×OPD]+.D\D&%R]WXù'1DWXUHRIWKH plate tectonic approach. Tectonophysics, 75(1981), 181-241. Crustal Structure of the Eastern Anatolian Plateau, Turkey. 7DQ 27DS×UGDPD] 0&<|UN$ 7KH (DUWKTXDNHV *HRGLQDPLFD$FWD Catalogues for Turkey. Turkish Journal of Earth Science, 17, <×OPD] < ûDURùOX ) *QHU < ,QLWLDWLRQ RI WKH 405-418. QHRPDJPDWLVP LQ (DVW $QDWROLD 7HFWRQRSKVLFV 8WNXFX 0 'XUPXüÞ + Geologica Acta, 15(2), 107-120 (2017) 120 DOI: 10.1344/GeologicaActa2017.15.2.3