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 Available in: http://www.redalyc.org/articulo.oa?id=50551303003 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Geologica Acta, Vol.15, Nº 2, June 2017, 107-120 DOI: 10.1344/GeologicaActa2017.15.2.3 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\LùLW2NXOGDü 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