Ankara Orogenic Phase, Its Age and Transition from Thrusting-Dominated Palaeotectonic Period to the Strike-Slip Neotectonic Period, Ankara (Turkey)

Ankara Orogenic Phase, Its Age and Transition From Thrusting-dominated Palaeotectonic Period to the Strike-slip Neotectonic Period, Ankara (Turkey)

AL‹ KOÇY‹⁄‹T & ﬁULE DEVEC‹

Middle East Technical University, Engineering Faculty, Department of Geological Engineering, Active Tectonics and Earthquake Research Laboratory, TR–06531 Ankara, Turkey (E-mail: [email protected])

Abstract: The Ankara section of the ‹zmir-Ankara-Erzincan Suture Zone (IAESZ) is characterized by two major groups of contractional structures, namely the Ankara forced folds-monoclines and the southward-verging foreland fold-imbricate thrust to reverse fault zone (AFITFZ). In the Ankara region, one of the areas where the various phases of deformation and related structures are particularly well-preserved and exposed is the Edige (Elmada¤) area, 48 km east-southeast of the city of Ankara. The youngest palaeotectonic unit in the AFITFZ, and deformed in the last phase of the palaeotectonic period (the Ankara orogenic phase) is the Edige formation. It consists of a fluvio-lacustrine sedimentary sequence mainly comprising basal conglomerate, shale, marl and a clayey limestone alternation dated as Turolian (MN 11) (Late Tortonian–Early Pliocene), based on its rich mammalian fossil content. The Edige formation was deposited within an extensional tectonic regime characterized by an oblique-slip normal faulting, in which the localized extension prevailed in approximately WNW–ESE direction. This first phase of extension was later replaced by a contractional tectonic regime and related successive and short-term phases of deformation such as folding, thrust to reverse faulting and finally strike-slip faulting which interrupted sedimentation of the Edige formation and deformed it. Both the stereographic plots of poles to bedding planes and the palaeostress analyses of slip-plane data recorded in the Edige formation and along its margin-boundary faults indicate that maximum horizontal stress operated in NW–SE direction during the phase of contraction. Finally, this last contractional tectonic regime (Ankara Orogenic Phase) was replaced by a strike-slip neotectonic regime. This is evidenced by an angular unconformity, which separates the underlying intensely deformed older rock assemblages including also the Turolian Edige formation from the overlying undeformed (nearly flat-lying) Edigekoru formation of Plio–Quaternary age. The strike-slip neotectonic regime in the Edige area initiated in Late Pliocene, has continued since that time under the control of active strike-slip faulting caused by a horizontal approximately N–S compression. This is indicated by three sets of approximately N–S strike-slip faults, namely the Elmada¤, K›l›çlar and Hisarköy fault sets in the study area, which comprise northeastern continuations of the Elmada¤, Balaban and Küreda¤ strike-slip fault zones, their activity proved recently by both the 2005.07.31, Mw = 5.2 Bala earthquake, and local concentration of numerous small earthquakes epicentres along their northeastern extensions, i.e., along the Elmada¤, K›l›çlar and Hisarköy fault sets.

Key Words: fold, imbricate reverse fault, strike-slip fault, suture zone, Ankara orogenic phase, Turkey

Ankara Da¤oluflum Evresi’nin Yafl› ve Bindirme Faylanmas›n›n Egemen Oldu¤u Eski Tektonik Dönemden Do¤rultu At›ml› Yeni Tektonik Döneme Geçifl, Ankara (Türkiye)

Özet: ‹zmir-Ankara-Erzincan kenet kufla¤›n›n (‹AEKK) Ankara kesimi, iki grup s›k›flma yap›s› ile karakterize edilir. Bunlar yükselmeye ba¤l› k›vr›mlar-tek kanatl› k›vr›mlar ile güneye bakan yay-önü k›vr›ml›-bindirimli ters fay kufla¤›d›r (AKBTFK). Ankara bölgesinde çeflitli deformasyon evrelerinin ve ilgili yap›lar›n en iyi korundu¤u ve yüzeyledi¤i yerlerden birisi Edige (Elmada¤) ve çevresidir. Edige, Ankara ‹lin’in 48 km do¤u-güneydo¤usunda yeral›r. Ankara yayönü k›vr›ml›-bindirimli ters fay kufla¤› içinde yer alan ve eski tektonik dönemin en son faz› ile (Ankara da¤ oluflum evresi) deformasyon geçirmifl olan engenç eski tektonik dönem birimi Edige formasyonudur. Edige formasyonu akarsu-göl ortam ürünü sedimanter bir istifle karakterize edilir. Zengin memeli fosil içeri¤ine göre Turoliyen (MN 11) (Geç Tortoniyen–Erken Pliyosen) yafll› olan formasyon taban çak›ltafl›, fleyil, marn ve killi kireçtafl› ardafl›m›yla temsil edilir. Edige formasyonu, normal faylanma ile karakterize edilen geniflleme türü tektonik rejimin denetiminde çökelmifltir ve çökelim s›ras›ndaki yerel geniflleme yönü yaklafl›k BKB–DGD dur. Daha sonra, bu ilk evre geniflleme rejimi, s›k›flma-daralma türü tektonik bir rejim ve bu rejim ile ilgili k›sa süreli deformasyon evreleriyle (örne¤in: k›vr›mlanma, küçük ve büyük aç›l› ters faylanma, do¤rultu at›ml› faylanma gibi) yer de¤ifltirmifltir. Bu deformasyon evreleri, bir taraftan Edige formasyonunun sedimantasyonunu kesintiye u¤ratm›fl, di¤er taraftan da formasyonu deforme etmifltir. Gerek katman kutuplar›n›n stereografik izdüflümleri, gerekse formasyon içinde ve formasyon kenar faylar› boyunca kay›d edilmifl olan fay aynas› verilerinin eskigerilim analizi, bu s›k›flma-daralma evresi s›ras›nda, en büyük s›k›flman›n KB–GD yönünde etkin oldu¤unu göstermifltir. Bu

433 NEOTECTONICS OF ANKARA REGION

enson s›k›flma-daralma türü eski tektonik rejim, daha sonra do¤rultu at›ml› yeni bir tektonik rejim ile yer de¤ifltirmifltir. Bu de¤iflim, altta yeralan ve ayn› zamanda Edige formasyonunu da içeren ye¤ince deformasyon geçirmifl daha yafll› kaya topluluklar› ile üstte yer alan ve deformasyon geçirmemifl (hemen hemen yatay konumlu) Pliyo–Kuvaterner yafll› Edigekoru formasyonunu birbirinden ay›ran aç›l› uyumsuzluk ile kan›tlan›r. Do¤rultu at›ml› yeni tektonik rejim Geç Pliyosen’de bafllam›fl olup, yaklafl›k K–G yönde etkin olan bir s›k›flman›n neden oldu¤u aktif do¤rultu at›ml› faylanma denetiminde Geç Pliyosen’den günümüze sürmektedir. Bu durum, Balaban, Elmada¤ ve Küreda¤ fay zonlar›n›n kuzeydo¤u uzant›lar›n› oluflturan ve inceleme alan› içinde yer alan Elmada¤, K›l›çlar ve Hisarköy fay tak›mlar›yla belirginlik kazan›r. Çünkü, enson oluflan 5.2 (Mw) büyüklü¤ündeki 31 Temmuz 2005 Bala depremi Balaban fay zonundan kaynaklanm›fl olup, ayr›ca küçük deprem episant›rlar› Elmada¤, K›l›çlar ve Hisarköy fay tak›mlar› üzerinde yo¤unlaflarak, bu fay tak›mlar›n› oluflturan do¤rultu at›ml› fay segmentlerinden baz›lar›n›n etkin (aktif) oldu¤unu kan›tlam›flt›r.

Anahtar Sözcükler: k›vr›m, bindirimli ters fay, do¤rultu at›ml› fay, kenet kuﬂa¤›, Ankara da¤oluﬂum evresi, Türkiye

Introduction (Figure 1B). However, most previous work carried out in Subduction, collision and suturing are progressive the Ankara section of ‹AESZ dealt only with the pre- and tectonic events occurring at active convergent plate syn-collisional characteristics of the suture zone (Erol boundaries and lasting for a long period of time. Based on 1954; fiengör & Y›lmaz 1981; Akyürek et al. 1984; Say›n 1985; Koçyi¤it 1987, 1991a; Gökten et al. 1988; Tüysüz their ages, these events can be classified as pre-collisional, et al. 1994; Toprak et al. 1996; Rojay & Süzen 1997; syn-collisional or post-collisional events. They determine Kaymakc› 2000; Koçyi¤it et al. 2003). In contrast, site, size and nature of the suture zones on the dynamic detailed and field-based previous studies of both the post- earth. One of the major compressional palaeotectonic collisional and neotectonic characteristics of the Ankara structures in northern Turkey is the ‹zmir-Ankara- section of ‹AESZ are very limited, and hence there are Erzincan suture zone (‹AESZ) (fiengör & Y›lmaz 1981) many geological problems which are still disputed by extending from ‹zmir in the west and trending eastwards authors (Nebert 1958; Erol 1980; Koçyi¤it 1991b, past Ankara, Erzincan towards the Caucasus Mountains 1992, 2003; Koçyi¤it et al. 1995; Gökten et al. 1996; further to the east (Figure 1A). The ‹AESZ is dominated Seyito¤lu et al. 1997; Demirci 2000; Kaplan 2004). by a polygenetic assortment of stacked and imbricate Some significant unresolved geological problems include: thrust fault-bounded zones made up of accreted and (1) what is the number, nature and duration(s) of the obducted components accumulated in both trench and tectonic regimes dominating the post-collisional fore-arc settings, which evolved during northerly oblique palaeotectonic period?; (2) how long have these regimes subduction and diachronous closure of the northern prevailed?; (3) what are the post-collisional geological Neotethyan Ocean (Görür et al. 1984; Koçyi¤it 1991a). structures?; and (4) when were the strike-slip Collision and suturing in the ‹AESZ is diachronous, i.e., neotectonic regime initiated in the Ankara region? The they started in the Maastrichtian and continued till the present paper aims to bring plausible solutions for these Early Miocene at different locations along the suture zone geological problems in the light of recent field data and (Seymen 1975; Saner 1980; fiengör & Y›lmaz 1981; related literature. Görür et al. 1984; Say›n 1985; Koçyi¤it 1987, 1991a; Tüysüz et al. 1994; Bozkurt et al. 1999; Okay et al. 2001; Koçyi¤it et al. 2003; Dokuz & Tanyolu 2006). Regional Tectono-stratigraphical Setting In general, sutures are geologically very complicated Allochthonous, para-autochthonous and autochthonous tectonic domains, due to superimposition of pre-, syn- rock assemblages are generally well-exposed in the and post-collisional tectonic events and related structures. Ankara region. Based on their occurrence ages, they are, Therefore, observing well-preserved structures and rock from oldest to youngest, classified into eight categories: sequences within the sutures is of great importance in (1) pre-Triassic Lalahan nappe, (2) Triassic Karakaya better understanding their tectonic settings and Nappe, (3) Upper Hettangian–Lower Campanian Ankara evolutionary histories. One of the type localities where Group, (4), Lower Campanian Anatolian Nappe, (5) the post-collisional structures are particularly well- Middle Campanian–Middle Eocene Memlik Group, (6) preserved and exposed is the Ankara section of the ‹AESZ Upper Campanian–Lower Pliocene K›z›lcahamam

434 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

f KIZLCAHAMAM MAGMATIC ARC e N COMPLEX d 25 km 18 c

b 17 ÇANKIRI T a E N 14 I N Kýzýlcahamam N T Peçenek C O HL S A K A R Y A 3 Pýnaryaka H Ç 19 5 8 9 Haydarköy AFiTFZ P 1 Nallýhan 7 Kazan 15 Gelbulasýn 2 Beypazarý 11 4 Çayýrhan BB HO 16 Yuvaköy 12 E 6 Ayaþ AFFZ ANKARA Edige Oran KIRIKKALE 10 13 Bedesten Beynam STUDY AREAS Dereköy ANKARA SECTION Bala

Haymana OF IAESZ

MENDERES - TAURIDE PLATFORM

ITSZ Black Sea IPSZ

SC A Kýrþehir E ÝAESZ Cihanbeyli Block ÝAESZ LAKE SALT I ITSZ Ar Menderes - Tauride Figure 1B BSZ A KO Platform Ý Arabian Platform A C B

Figure 1. (A) Simplified map showing major suture zones in Turkey and its neighborhood (modified from Koçyi¤it et al. 1995). BSZ– Bitlis Suture Zone, ‹AESZ– ‹zmir-Ankara-Erzincan Suture Zone, IPSZ– Intra-Pontide Suture Zone, ITSZ– Inner Tauride Suture Zone, A– Ankara; E– Erzincan, I– ‹zmir, SC– Sakarya Continent; (B) simplified map showing major compressional structures characterizing the Ankara section of the ‹AESZ. AFFZ– Ankara forced fold zone, AF‹TFZ– Ankara foreland fold-imbricate thrust fault zone, 1– Nall›han thrust fault, 2– P›narbafl› (P) thrust fault, 3– Peçenek reverse fault and overturned contact, 4– Çay›rhan-Beypazar› monocline-reverse fault and overturned contact, 5– Çeltikçi (Ç) monocline and reverse fault, 6– Ayafl monocline and reverse fault, 7– P›naryaka folds, 8– Baflbereket (BB) monocline and reverse fault, 9– Kazan monocline and reverse fault, 10– Dereköy thrust fault, 11– Yuvaköy thrust fault, 12– Oran thrust fault, 13– Hasano¤lan (HO) thrust fault, 14– Hac›lar (HL) thrust fault, 15– Haydarköy thrust fault, 16– Gelbulas›n thrust fault, 17– Hanc›l› (H) thrust fault, 18– Elmada¤ (E) thrust to reverse fault, 19– Bedesten thrust fault, 20– Elmada¤ strike-slip fault zone, 21– Balaban strike-slip fault zone, 21– Küreda¤ strike-slip fault zone; a– K›rflehir block, b– Menderes-Tauride platform, c– K›z›lcahamam magmatic arc complex, d– granite- granodiorite, e– reverse-thrust faults, f– folds; (C) very simplified map showing approximate outline of the Karakaya orogenic belt (KO), Ar– Artvin.

435 NEOTECTONICS OF ANKARA REGION

magmatic arc complex, (7) Oligo–Miocene fluvio- mélange or subduction complex accreted at the south- lacustrine and volcano-sedimentary sequences, and (8) facing northern active margin of the northern Neotethyan Plio–Quaternary neotectonic units (Erol 1951, 1954, Ocean (Koçyi¤it 1991a). It displays both normal 1955; Norman 1972; Batman 1978; Akyürek et al. stratigraphical and tectonic contact relationships with 1984; Koçyi¤it 1987, 1991a; Koçyi¤it & Lünel 1987; rock assemblages in age ranging from Triassic to Early Koçyi¤it et al. 1988; Kazanc› & Gökten 1988; Gökten et Pliocene (Koçyi¤it 1987, 1991a; Koçyi¤it et al. 1995). al. 1988; Koçyi¤it et al. 2003). The Memlik Group is an approximately 1.5 km thick The Lalahan Nappe, a product of the Hercynian sedimentary infill deposited in the north-northwestern orogeny, occurs in two NE-trending belts 2–15 km wide part of the Haymana-Polatl› accretionary fore-arc basin, characterized by polyphase metamorphic rocks intruded which was one of diagnostic structures of the northern by metadiabase and serpentinized basaltic dykes. They Neotethyan Ocean. It consists of a coarsening-upward consist mostly of metabasic rocks (albite-diabase, spilitic sequence of Middle Campanian–Middle Eocene age basalt, basalt, volcanic breccia and tuff), amphibolite, (Koçyi¤it 1991a). At the bottom, the Memlik Group greenschist, meta-ultramafic rocks, phyllite, calc-schist, displays a stratigraphically conformable boundary graphite schist, marble, quartzite and metaclastic rocks. relationship with the ophiolitic mélange of the Anatolian It is thrust southeastwards on to the younger Karakaya Nappe, although it is overlain with an angular Nappe. The Karakaya Nappe occurs in a NE-trending belt unconformity by the post-collisional fluvio-lacustrine 3–18 km wide, and 60 km long in the Ankara region. It sedimentary and volcano-sedimentary sequences of ≥ is a tectono-sedimentary chaotic mixture of blocks of Oligocene–Early Pliocene age at the top. This 1-km- high- to low-grade metamorphic rocks, mafic to thick continental sequence consists mostly of fluvial red ultramafic rocks, deep- and shallow-water carbonates of beds, coal seam-bearing lacustrine shales, carbonates to Carboniferous–Triassic age, litharenites and radiolarian evaporates, and andesitic-basaltic volcanics and cherts set in a slightly metamorphosed but intensely volcaniclastics (Erol 1951, 1954, 1955; Koçyi¤it et al. sheared litharenitic to shaly matrix. The Karakaya Nappe 2003; Kaymakc› 2000). One of the most widespread and is a product of the Karakaya orogeny and it is Middle to diagnostic rock assemblages, recording northerly Late Triassic in age based on fossils identified in its matrix subduction of the northern Neotethyan Ocean floor in the (Okan 1982; Koçyi¤it 1987; Alt›ner & Koçyi¤it 1993). Ankara region, is the K›z›lcahamam magmatic arc The Karakaya Nappe is also thrust southeastwards onto complex (Figure 1B). Previously and erroneously named the younger Anatolian Nappe (Koçyi¤it 1987; Koçyi¤it et the ‘Galatean Arc Complex’ using the national name of an al. 1995). The Ankara Group occurs in various-sized and ancient civilization (Galatia) by Koçyi¤it et al. (2003), in discontinuous outcrops in Ankara region. In a normal this paper, it is renamed the K›z›lcahamam magmatic arc stratigraphical position, it overlies with an angular complex, using the geographical name (K›z›lcahamam unconformity the Lalahan and the Karakaya nappes, and County) of the type locality where it is well-exposed. The consists, from bottom to top, of six different lithofacies K›z›lcahamam magmatic arc complex evolved in three such as fluvial basal conglomerate, shallow-marine clastics stages, namely the pre-, syn- and post-collisional stages, with the intercalation of widespread Rosso-Ammonitico to be an intra- and back-arc settings comprising the facies, open shelf to slope carbonates, fine-grained deep- south-facing northern active margin of the northerly marine sedimentary facies, sedimentary mélange and subducting northern Neotethyan Ocean (Koçyi¤it 1991a; again deep-marine shale and mudstone (Koçyi¤it 1991a). Koçyi¤it et al. 2003). It consists mainly of calc-alkaline Based on its very rich fossil content, the Ankara Group is and alkaline volcanic rock assemblages (trachyte, dacite, late Hettangian–early Campanian in age (Koçyi¤it 1987, andesite, basalt and their pyroclasts up to 2.5 km total 1991a). At the top, the Ankara Group is overthrust by thickness) ranging in age from Middle Campanian to Early the Anatolian Nappe (Koçyi¤it 1991a). The Anatolian Pliocene (Ach 1982; Koçyi¤it & Lünel 1987; Tokay et al. Nappe, a product of the Alpine orogeny, occurs in 1987; Keller et al. 1992; Wilson et al. 1997; Bozkurt et widespread but variably-sized and discontinuous outcrops al. 1999; Koçyi¤it et al. 2003). The K›z›lcahamam along the ‹AESZ. It is dominated by the magmatic arc complex accompanies Late Cenomanian–Lower Campanian coloured ophiolitic Cretaceous–Early Tertiary fore-arc marine sedimentation and Oligo–Miocene continental sedimentation recording

436 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

the subductional-, collisional- and post-collisional the last phase of the contractional palaeotectonic period evolutionary history of the northern Neotethyan Ocean recorded within the rocks and their tectonic contacts in floor. The youngest and undeformed unit, which records the Edige area (Figure 1B). the neotectonic regime in the Ankara region, consists of uplifted and dissected terrace conglomerates of Plio–Quaternary age, and weakly consolidated to loose Stratigraphy of the Edige Area conglomeratic sandstones to fine-grained alluvial Based on both the age and style of deformation, the rocks sediments of Quaternary age. in the Edige area are subdivided into two categories: (1) The Ankara section of the ‹AESZ is geologically very pre-Late Pliocene allochthonous to para-autochthonous complicated (Figure 1). This is because (a) remnants of rock assemblages that represent the palaeotectonic the Sakarya Continent, K›rflehir block, the Menderes- period, and (2) Plio–Quaternary autochthonous rocks Tauride platform and the intervening sutures (‹zmir- (Edigekoru formation) and sediments representing the Ankara-Erzincan and the ‹nner Tauride sutures) are neotectonic period which are nearly flat-lying and overlie juxtaposed tectonically (Figure 1B), and (b), except for with angular unconformity the erosional surface of the the Plio–Quaternary neotectonic unit, all the above- intensely deformed and tectonically transported mentioned rock assemblages (metamorphosed paleotectonic rock assemblages. Based on their Hercynides, unmetamorphosed Alpides and their volcanic occurrence ages, palaeotectonic units exposed in the and molassic cover), ranging in age from pre-Triassic to Edige area are, from oldest to youngest, the Karakaya Early Pliocene, have been superimposed, and even Nappe, the Eskiköy nappe, the Anatolian Nappe and the tectonically stacked up by two groups of contractional para-autochthonous Edige formation. They will be structures, namely the Ankara foreland fold-imbricate described in more detail below. thrust to reverse fault zone (AF‹TFZ) and the Ankara forced fold zone (AFFZ) as a result of both the Palaeotectonic Rocks subduction-to collisional- and long term post-collisonal events (Figure 1B). The AFFZ controls the north- Karakaya Nappe northwestern half of the ‹AESZ and is composed mainly Discontinuous outcrops of a widespread Triassic rock of a number of NE–SW-trending and southeast-verging assemblage are best exposed in an approximately E–W- monoclinal to overturned folds and high-angle thrust trending belt running from the Biga Peninsula in the faults (reverse faults) such as the Çay›rhan-Beypazar› and west-southwest and extending throughout the southern the Ayafl-Pazar monoclinal to overturned folds and the part of Black Sea region in northern Turkey as far as Nall›han thrust fault (Koçyi¤it 1991b; Demirci 2000) Artvin in the east-northeast (Figure 1C). In this belt, the (Figure 1B). The AF‹TFZ shapes the south-southeastern pre-Triassic Hercynian, Late Triassic Karakaya and the half of the ‹AESZ, and consists of a series of NNE–SSW- Late Cretaceous Alpine orogenies, and their structures are trending and SSE-vergent imbricate thrust faults, such as superimposed on each other in a thick imbricate stack; the Haydarköy, Gelbulas›n, Hanc›l›, Elmada¤, and therefore the geology of this belt is very complicated. Bedesten thrust faults, along which both the Hercynides This rock assemblage was first recognized and named by (Lalahan Nappe) and the Alpides (the Karakaya and Bingöl et al. (1973) as the so-called ‘Karakaya Formation’ Anatolian nappes) are emplaced onto the Upper in the Biga Peninsula, comprising the western part of the Miocene–Lower Pliocene fluvio-lacustrine sedimentary belt. fiengör & Y›lmaz (1981) and Tüysüz & Yi¤itbafl and volcano-sedimentary sequences (Koçyi¤it 1992; (1994) had previously interpreted the same rock Koçyi¤it et al. 1995). One of the type localities, where the assemblage to be a marginal basin succession of the structures recording the last phase of the palaeotectonic southerly subducting Palaeo-Tethys. This rock period and related contractional features are well- assemblage, together with its basement composed of preserved, is the Edige (Elmada¤) area, located ~48 km polyphase low-grade metamorphics, was termed the east-southeast of city of Ankara (Figure 1B). One of the Upper Permian–Triassic ‘Karakaya Complex’ by Okay main aims of the present paper is to discuss and present (1984), who also incorporated the ‘Karakaya Complex’ structural analysis of contractional features representing within the the ‘Sakarya Zone’. Koçyi¤it (1987, 1991c)

437 NEOTECTONICS OF ANKARA REGION

extended the belt of Triassic rock assemblage eastwards is thrust from NW to SE on to various tectono- to the Artvin area and named it the Karakaya orogen stratigraphic rock units, such as the Anatolian Nappe, the (Figure 1C). Eskiköy nappe and the Edige formation, ranging in age In the western part of the Karakaya Orogen (Biga from Early Cretaceous to Early Pliocene (Figure 3). All Peninsula and Bursa-Bilecik areas), Triassic rocks are these allochthonous and para-autochthonous units and para-autochthonous, and were therefore named the their normal stratigraphic or faulted contacts are overlain Karakaya group, composed of three subunits (Koçyi¤it et with angular unconformity by the Plio-Quaternary al. 1991b). These are from bottom to top, arkosic clastic Edigekoru formation (Figures 2 & 3). Therefore the rocks approximately 1 km thick (Kendirli Formation), an emplacement age of the Karakaya Nappe into its present alternation of spilitic pillow basalt flows, pyroclastic rocks position is bracketed between Early Pliocene at bottom and shallow-water carbonates (Bahçecik Formation), and and Late Pliocene at the top. a sedimentary mélange of wildflysch type (Olukman Formation). The latter is a chaotic mixture of various Eskiköy Nappe blocks of differing origin, age, texture, structure and facies set in an intensely sheared litharenitic to pelitic This unit, previously named the ‘Edige ultramafic body’ matrix. It also contains diverse-sized low-grade (Say›n 1985), was renamed the Eskiköy nappe due to its metamorphic blocks derived from its basement (Lalahan allochthonous nature, as it has been transported tens of Nappe in the Ankara region). The age of carbonate blocks kilometres from its place of origin to its present position. in the matrix of the Karakaya Group ranges from The Eskiköy nappe is another widespread allochthonous Carboniferous to Norian (Okan 1982; Koçyi¤it 1987; unit exposed and mapped at a scale of 1/25.000 in the Koçyi¤it et al. 1991a; Alt›ner & Koçyi¤it 1993; Okay & Edige area (Figure 3). It occurs in more than one Mostler 1994; Alt›ner et al. 2000). southeastward facing tectonic slice within a NE–SW- trending belt 0.6–2.6 km wide, 10 km long, located in In the Biga Peninsula and the Bursa-Bilecik areas, the the Karacahasan, Edige and Hisarköy areas (Figures 3 & Karakaya group rests unconformably on the erosional 4). The Eskiköy nappe originally represents a deeper and surface of the pre-Triassic and polyphase metamorphic layered structure of the northern Neotethyan ocean floor rocks, and it is overlain with angular unconformity by a and consists of both ultramafic (harzburgite, dunite, ≥ well-defined basal conglomerate, a few metres to 1 km pyroxenite and chromatite) and mafic rocks thick, which is the lowest unit of the Upper (serpentinized dunite, pyroxenite and massive to layered Hettangian–Lower Campanian Ankara Group (Koçyi¤it gabbro occurred in podiforms). Both these rock 1987, 1991a; Koçyi¤it et al. 1991a, b; Alt›ner et al. assemblages are also accompanied by closely-spaced and 1991; Koçyi¤it & Alt›ner 2002). Exceptionally, in the irregular magnesite and jel-silica veins (up to 20 cm in Hal›lar area of the Biga Peninsula, the Karakaya Group thickness), and in places cut across by 1–20-m-long, grades upward into the Jurassic unit indicating the 0.2–15-m-thick and NE–SW-trending doleritic to diorite presence of a remnant Karakaya basin and the dykes (Figure 5). Both the top and the bottom tectonic diachronous nature of the Karakaya Orogeny (Koçyi¤it & contacts of the Eskiköy nappe are represented by Alt›ner 1990; Alt›ner & Koçyi¤it 1992). In contrast to the northwesterly dipping imbricate reverse faults with the situation in the western Karakaya Orogen, in the Ankara Triassic Karakaya Nappe, the Cenomanian–Lower region one of the sub-units (Kendirli Formation) of the Campanian Anatolian Nappe and the Upper Karakaya group is missing, and the remaining two sub- Miocene–Lower Pliocene (Turolian) Edige formation units (Bahçeli and Olukman formations) together (Figures 2 & 3). The emplacement age of the Eskiköy comprise an undifferentiated chaotic allochthonous nappe into its present-day position is a time slice between tectono-sedimentary mixture. Therefore, this chaotic Early Pliocene and Late Pliocene, based on its contact mixture of Triassic age was renamed the Karakaya Nappe relationship (Sivritepe and Edige imbricate reverse faults) in the Ankara region (Koçyi¤it 1987, 1991c). The with the youngest palaeotectonic unit, the Upper Karakaya Nappe displays widespread but discontinuous Miocene–Lower Pliocene Edige formation (Figures 2 & outcrops in an approximately NE–SW-trending belt, and 3).

438 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

TECT. Age Unit Thick LITHOLOGY DESCRIPTION PERIOD

unsorted, weakly consolidated, polygenetic 30 m fluvial conglomerate Plio- PERIOD

NEOTECT.

Formation Edigekoru Quaternary U - angular unconformity

tectono-sedimentary chaotic mixture of various blocks within an intensely sheared litharenitic to pelitic matrix Nappe ~1.5 km Triassic Karakaya X3. tectonic contact (reverse fault)

coloured ophiolitic melange Early Nappe ~ 300 m Anatolian Campani. X2. tectonic contact (reverse fault)

altered ultramafic rocks (harzburgite, dunite, pyroxenite) cut by magnesite veins ~ 700 m

light green-blue mafic rocks (serpentinized dunite, pyroxenite and gabbro) 30 m

Eskiköy Nappe pale brown, porous, highly altered (silicified and calcitized) serpentinite 40 m Early Cretaceous Early fault breccia 20 m 5 m fault gouge and C-S structures X1. tectonic contact d d: unsorted, polygenetic, poorly bedded red conglomerate c: brown-blue-white lacustrine shale-marl-siltstone alternation b: red sandstone-siltstone-mudstone alternation with lensoidal channel conglomerate intercalation b a: unsorted, polygenetic basal conglomerate 80 m F: site of mammalian fossils Promephitis hootoni, Promephitis sp., Parataxidea maraghana, Parataxidea sp., Ictitherium robustum, Ictitherium h ipparianum, Cr ocuta eximia, Epimachairodus roemeri, Choerolophodon (Mastadon?) pentelici,

Formation Hipparion gdacile, Ceratotherium neumayri (Diceros pachygnathus?), F Chilotherium kowalevskii (Aceratherium sp. ?), Rhinocerotidae indet,

Microstonyx erymanthius (Sus erymanthius?), Giraffa sp., Tragoceros

c PERIOD PALAEOTECTONIC amaltheus, Helicotragus rotundicornis, Palaeoryx pallasi, Oioceros rothii,

Edige Gazefla gaudry, Gazella capricornis, Gazella eleanorae, Artiodadyla indet

70 m based on Rhinocerotidae, the age of the fossil

Turolian (Late Tortonian - Early Pliocene) Tortonian (Late Turolian 20 m a level is Early Tu rolian (MN11) U - angular unconformity

coloured ophiolitic melange 0.5 - 1.5 km 1.5 - 0.5

Anatolian Nappe (not to scale) Early Campanian Early

Figure 2. Generalized tectono-stratigraphical column of the Edige area.

439 NEOTECTONICS OF ANKARA REGION 0 0 52 48 16 19 70 30 26 38 TF

dike strike and dip of bedding anticline axis syncline axis tear fault thrust fault oblique-slip normal fault strike-slip fault with normal-slip component olistholith contact lines of geological cross-sections stations where slip-plane data were measured T

F D

U B

R 40 H

80 C I

B 28

M I A

C TF

70 E

36 P

45 T 36 E

L 3 x Öteyüzbaðlarý A

T S F

L T

L Kaletepe

U 46

A I

T E

52 S

80 U Ý

28 R 6

H 35

60 T 18 E

E 40 T

C I

B 36

alluvium Edigekoru formation angular unconformity Karakaya Nappe tectonic contact Eskiköy nappe tectonic contact Anatolian Nappe tectonic contact Edige formation

M 6 I

Ý EDÝGE

2 R

Ý H. S Kaklýk 1185 0 5 Sivri H. 1047 Edigekoru H. 1112 1 16 0 86 12 Küçükedige 0 1266 0 36 45 TF Kayýncak H. 15

Eskiköy

A F

T S

C U R H T B 20

T 30

C I 22 16

R 24

M 22 I 32 32 ELMADAÐ

Ð 25 A 35 18

D A

28 M 1328

38 L

30 E FL T 39 Korukaþý H. L 50 20

F 42 26 4

T 37

S 32

R H

H. T 38

Hüyük Tümbek H. Viyadük E

15 1294 T

30 A

R Doyransýrtý B

K E M B Ü T 42 TF 50 Geological map of the Edige area. N A KARACAHASAN 1 Km

35 ELMADAÐ FAULT ELMADAÐ Figure 3.

440 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

Anatolian Nappe and their internal structures are well-exposed is the This tectonic unit was previously named the ‘Anatolian K›z›lda¤ (Hisarköy-Elmada¤) area (Figure 4 & 6). Complex’ by Koçyi¤it (1991a). However, it was renamed Imbricates or tectonic slices are mostly in fault contact the Anatolian Nappe by Koçyi¤it et al. (1995) as it had with each other. Some of these imbricate reverse fault- been tectonically transported a long distance. In general, bounded slices of dissimilar age, lithofacies and origin the Anatolian Nappe is an undifferentiated coloured occur in fault-parallel strips of contrasting colours, which ophiolitic mélange or subduction complex accreted at the commonly correspond to the internal smaller imbricate south-facing northern active margin of the northerly structures characterizing the Anatolian Nappe. Pinch- and subducting northern Neo-Tethyan ocean floor (ﬁengör & swells, bedding pull-aparts, dispersed phacoids of Y›lmaz 1981; Koçyi¤it 1991a; Koçyi¤it et al. 2003). sandstones and limestones, disrupted beds, hinges and In general, the Anatolian Nappe is a chaotic tectono- folds (closed, upright, overturned, recumbent, isoclinal sedimentary mixture of various blocks of dissimilar age, and disharmonic folds), quartz- and/or calcite-filled shear origin, facies and size set in a pervasively sheared, semi- planes, spaced to axial-plane cleavages, local thrust to schistose and/or mylonitized fine-grained matrix reverse and normal faults and discrete thrust nappes are composed of sandstone, which contains mostly detrital common mesoscopic-scale features observed within the ophiolitic material, shale, turbidite and pelagic mudstone. trench fill turbidites, Rotalipora-bearing mudstone of Blocks in it range from a few centimetres to tens of Cenomanian age, radiolarian-rich wackestone, radiolarian kilometres in size. They are generally lensoidal and cherts and the volcaniclastic sedimentary pile. All these irregular in shape, and rootless. Secondary features seem to have resulted from a single progressive mineralization, such as calcitization and silicification, is deformation changing from an early stage ductile flow to most common on polished and striated block surfaces. advanced stage brittle failure, due to simple shearing Based on their origins, blocks fall into four major which prevailed at the base of the inner trench slope categories: (1) passive continental margin-derived blocks, during rapid subduction of a relatively thin trench floor which are dominated by carbonate blocks of dissimilar sequence (Moore & Wheeler 1978; Moore 1979; Moore age and facies (blocks of the Ankara Group of Koçyi¤it & Karig 1980; Nelson 1982). 1991a); (2) active continental margin-derived blocks, The apparent thickness of the Anatolian Nappe in the which are mostly volcanic to ophiolitic material-rich study area is about ≥ 1 km, and the youngest block olistostromes, turbidites and broken formations (Figure identified within its clastic matrix is a thin bedded, pinkish 6); (3) ocean floor-derived blocks, mostly ultramafic to to red pelagic biomicrite of Santonian–Early Campanian mafic rocks and their sedimentary cover comprising the age (Koçyi¤it 1991a). Further north, outside the study oceanic lithosphere such as harzburgite, pyroxenite, area, the Anatolian Complex comprising the Anatolian dunite, serpentinized dunite, gabbro, chromitite, pillowed Nappe, is overlain depositionally by Middle Campanian basalt, diabase, manganese-bearing radiolarian chert, olistostromal levels of the K›z›lkaya Formation, at the tuff-tuffite, other pyroclastic rocks, radiolarite, base of a well-preserved and defined accretionary radiolarian-rich wackestone, pelagic cherty limestone peripheral fore-arc sequence (Koçyi¤it 1991a). Thus, the interbedded with red radiolarian chert bands and volcanic youngest growth age of the Anatolian Complex as an breccias (Figures 4 & 6), and (4) older basement-derived accretionary prism at the base of south-facing inner slope blocks, such as marble, recrystallized limestone, of the northern Neotethyan oceanic trench is Middle greywacke, fossiliferous limestone blocks of Campanian. However, the emplacement age of the Carboniferous, Permian and Triassic ages, and low-grade Anatolian Complex as the Anatolian Nappe into its present metamorphics such as green schist and metabasic rocks position is a time slice between Early Pliocene and Late of the Lalahan Nappe. The active margin- and ocean floor- Pliocene (Figures 2 & 3). derived blocks display mostly a more regular tectono- Unfortunately, all these allochthonous units (The stratigraphical sequence within a thick tectonic slice or Lalahan Nappe, the Karakaya Nappe, the Eskiköy nappe imbricate stack bounded by imbricate thrusts to reverse and the Anatolian Nappe), described briefly in previous faults (Figures 3, 4 & 6). One of the type localities where sections were formerly and erroneously combined into a the Anatolian Nappe, its various lithological components single tectonic unit named the so-called ‘Ankara Mélange’

441

NEOTECTONICS OF ANKARA REGION

T T T

L L L

U U U

A A A

F F F

T T T

S S Kýlýçlar R. S

U U U

R R R

H H H

T T T

E E E

T T T

A A A

s Eskiköy nappe, 4– C C C

I I

I Limestone blocks 6–

R R R

B B B

st to reverse faults, 10– M M M

I I I

), 5b– pillowed basalt, 5c–

, and 13– line of geological of line 13– and ,

K K K

I I

I F L L L

R R R

I I I

K K K

0 A A A

B B B

T T T

L L L

U U

U 12

A A A

F F F

T T T

S S S

U U U

R R R

H H H

T T T

11 E E E

T T T

A A A

C C C

I I I

R R R 10

B B B

M M M 50

I 9 48

A 8 D

I 1123 Z I 65 KIZILDAÐ

T T T

L 7

U 6 E.HÝSARKÖY

C 5e

Hacýoðlu

R R R

B B B

M M M

I I I

U U U

L L L 5d

Ð Ð 45 Ð

O O O

I I I

C C C

A A A

H H H 5c 52 40 5b

Korubaðý R.

Balaban R. R. R. Balaban Balaban Balaban 34 5a HÝSARKÖY 84

KOCATEPE FAULT FAULT FAULT KOCATEPE KOCATEPE KOCATEPE 28 E

Kocatepe str. str. str. Kocatepe Kocatepe Kocatepe 2 cross- sections. Dolerite-diorite dike, 5a– undifferentiated coloured ophiolitic mélange (mostly matrix of blocks comprising the Anatolian Nappe bedded-massive radiolarite to pelagic limestone alternation, 5d– Upper Cretaceous a flyschoidal sequence, Plio–Quaternary 5e– fluvial clastics Permian–Jurassic (Edigekoru formation), 7– Quaternary alluvial sediments, 8– strike and dip section measured of of line 12– bedding, component, strike-slip with 9– fault normal Oblique-slip thru 11– component, normal with fault strike-slip Geological map of the K›z›lda¤ (Hisarköy-Edige) area. 1– Turolian Edige formation, 2– Tectonic contact (TC), 3– Lower cretaceou TC 1 20 Figure 4.

442 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

Figure 5. Close-up view of a doleritic dyke cutting across calcitized and silicified serpentinite (~150 m NW of Edige village). by Bailey & McCallian (1953). Instead, regional has an erosional stratigraphical bottom contact with both unconformities, rift and passive to active margin the Eskiköy and Anatolian nappes, but a faulted top sequences separating them at well-preserved outcrops contact with the same units (Figure 3). The Edige showing normal stratigraphical relationships indicate that formation, from bottom to top, consists of four major they are separately mappable products of different lithofacies: (a) basal conglomerate, (b) fluvial sandstone- orogenies (the Hercynian, the Karakaya and the Alpine mudstone alternation, (c) lacustrine shale-marl and orogenies, respectively) in the ‹AESZ (Koçyi¤it 1987, limestone alternation, and (d) unsorted conglomerate 1991a, c; Koçyi¤it et al. 1991a; Alt›ner & Koçyi¤it 1993; (Figure 3). The basal conglomerate is green-yellow-red Alt›ner et al. 2000; Koçyi¤it & Alt›ner 2002). and variegated in colour, and polygenetic to unsorted in nature. It consists of well-rounded pebbles, cobbles and boulders derived from allochthonous rock assemblages Edige Formation mentioned above. Clasts up to 30 cm in diameter are The type locality of this formation is Edige and adjacent mostly radiolarite, marble, recrystallized limestone, areas, where it is well-exposed and displays well-bedded greywacke, spilitic basalt, gabbro, serpentinite, turbiditic internal structure. The Edige formation crops out within sandstone, chert, cherty limestone, dunite and andesite several 0.2–3 km wide and approximately NE–SW- clasts. The conglomerates are debris-flow to braided river trending belts around Karacahasan and Edige villages. It deposits with an iron-rich matrix and calcite cement. They

443 NEOTECTONICS OF ANKARA REGION

siltstone and mudstone alternation with the intercalation LITHOLOGY DESCRIPTION of various sized and lensoidal channel conglomerates or (m)

Thickness scour-and-fill structures, which indicate a flood plain 26 radiolarite-argillaceous limestone alternation depositional setting. This 130-m-thick flood plain deposit displays a lateral facies change into a lacustrine blue- green-white and light brown shale-marl and limestone 78 basalt alternation up to 70 m in thickness. Both the flood plain and the lacustrine deposits are overlain conformably by a weakly lithified to loose red conglomerate ranging from a few metres to 50 m in thickness (Figure 3).

pillowed basalt The Edige formation contains rich mammalian fossils 100 in places, particularly along the transitional zone between its flood plain and lacustrine facies. One of these fossil localities and its rich fossil assemblage, plotted and listed on the tectono-stratigraphical column (F in Figure 3), was 35 spilitic volcanic breccia previously detected and identified by Saraç (1994). Based 13 pillowed basalt on this fossil assemblage, the key horizon labelled by 6 radiolarian limestone letter F, that indicates the fossil location within the Edige 29 pillowed basalt formation, is Early Turolian (MN 11) (Upper Tortonian) 8 nodular, siliceous limestone with radiolaria in age. However, the sequence including the fossil 10 manganese-bearing radiolarite 8 siliceous mudstone location continues upwards for about 100 m in thickness, 9 spilitic olistostrome 6 radiolarite therefore, the remaining upper part of the sequence may 14 spilitic olistostrome continue up to uppermost Turolian (Early Pliocene) in 18 radiolarite-tuffite alternation age. Thus, the age of whole continental sequence was 24 radiolarite-argillaceous carbonate alternation accepted to be Turolian (Upper Tortonian–Early Pliocene) 15 laminated tuff-tuffite in the present paper.

Neotectonic Rocks These rocks and sediments accumulated during the 40 spilitic olistostrome neotectonic regime in the Ankara region. Neotectonic units are characterized by mostly uplifted and dissected river to fault terrace conglomerates of Plio–Quaternary age suspended at different elevations along the margin- TC 34 foliated serpentinite boundary faults, and the depocentral Quaternary TC spilitic olistostrome ( 4 m) sediments accumulated inside the active basins (Koçyi¤it foliated serpentinite ( 3 m) 1991b). One of the neotectonic units is well-exposed at TC calcareous radiolarite (2 m) 25 foliated serpentinite limited and isolated outcrops in the Edige area, where it TC is named as the Edigekoru formation (Figures 2 & 3). 20 dolerite-gabbro (TC: tectonic contact) This unit is described below.

Figure 6. K›z›lda¤ measured tectono-stratigraphical measured section of the lithologies comprising a tectonic slice within the Edigekoru Formation Anatolian Nappe. This fluvial terrace conglomerate is exposed at three outcrops north and south of Edige village (Figures 3 & 4). are a few meters to 20 m thick, and overlie the older The type locality of the formation is the Edigekoru rocks with angular unconformity. They grade upward district, where the internal structure and its basal contact into the red conglomeratic sandstone, sandstone,

444 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

with the youngest palaeotectonic unit, the Upper within horizontal lacustrine beds, and a Plio–Pleistocene Miocene–Lower Pliocene Edige formation, are well- age (MN 14-17) was assigned to them by Saraç (2003). exposed (Figure 7). At this locality, in a road cut, the The fine-grained horizontal beds of the Edigekoru Edigekoru formation overlies with angular unconformity formation can be correlated with those of Saraç (2003), the steeply dipping and folded Edige formation. A 20–50- and may also be Plio–Quaternary in age. The age of the cm-thick, unsorted and weakly consolidated polygenetic Edigekoru formation has a critical significance in Ankara basal conglomerate rests on the erosional surface of the region, because, it is undeformed (nearly flat-lying) and Edige formation, and is overlain by an alternation of seals all the intensely deformed palaeotectonic units and horizontal beds of conglomeratic sandstone, siltstone, their tectonic contacts, i.e. it is a key for the end of the mudstone with the intercalation of lensoidal channel contractional palaeotectonic period (Ankara Orogenic conglomerates (Figure 7). The top of the unit is a free Phase) and the initiation of the strike-slip neotectonic erosional surface, represented by loose boulder-block period in Ankara region. conglomerate. The lower coarse-grained horizons interfinger with the fine-grained lacustrine shale and marls, in places (Saraç 1994). At the type locality, the Geological Structures in the Edige Area thickness of the formation is 2 m, but it ranges up to 30 Based on their ages and styles, the geological structures m maximum at other localities. exposed in the Edige area and its neighborhood are In the Edige area, no fossils were found within the classified into two major categories: (a) palaeotectonic formation, but it is also exposed at a number of outcrops structures such as the normal faults, folds and imbricate elsewhere within the ‹AESZ. It is especially well-preserved reverse faults, and (b) neotectonic structures such as in the Sar›larbey (Kazan-Ankara) area, outside the strike-slip faults. They will be analysed and described present study area, where a mammalian fossil from the separately below. Arvicolinae family and Rodentia Class was identified Palaeotectonic Structures Normal Faults These structures occur in two patterns: (1) the mappable and isolated margin-boundary faults between the Turolian Edige formation and older rocks, and (2) mesoscopic fault arrays within the Edige formation. Particularly the Sivritepe imbricate reverse fault was an originally SSE-dipping oblique-slip normal fault (margin- AU boundary fault), which controlled sedimentation of the Edige formation during the Turolian. The Sivritepe imbricate reverse fault is well-exposed on the SSE side of Sivritepe, approximately 1 km northwest of Edige village (Figure 8), and it exposes well-preserved superimposed slickensides indicating three phases of deformation, firstly SE-dipping oblique-slip normal faulting, secondly NNW- dipping reverse faulting, and finally NE–SW-trending sinistral strike-slip faulting. This is precisely proved by the well-preserved slickensides (Figure 9a). Kinematic analysis of the slip-plane data measured on the slickensides at Station 1 (Figure 3) reveals the first phase Figure 7. Close-up view of the angular unconformity (AU) between the overlying nearly flat-lying Plio–Quaternary Edigekoru of deformation to be an oblique-slip normal faulting with formation and the steeply dipping Turolian (Upper WNW–ESE extension (Figure 9b) during the Tortonian–Lower Pliocene) Edige formation (~1.2 km sedimentation of the Turolian Edige formation. This first WNW of Edige village).

445 NEOTECTONICS OF ANKARA REGION

Sivritepe

Sivritepe Imbricate Reverse Fault

Eskiköy Nappe

Edige formation

Figure 8. Field photograph showing general view of the Sivritepe imbricate reverse fault (view to NE, 1.2 km NW of Edige village). phase of extension is also strongly evidenced by the very Pliocene times following its sedimentation. This first widespread normal fault arrays recorded and preserved phase of contractional deformation is also evidenced by a within the Edige formation (Figure 9c). Kinematic series of SSE-verging imbricate reverse faults (Figure 3). analyses of slip-plane data measured on slickensides at Stations 2 and 3 (Figure 3) reveals again the same phase of deformation by the oblique-slip normal faulting and Imbricate Reverse Faults NW–SE extension (Figure 9d & e). The Edige area is a type locality for the foreland fold- imbricate reverse fault zone characterizing the ‹AESZ. This area is shaped by a series of closely-spaced, SSE- Folds verging and NE–SW-trending imbricate reverse faults. The Turolian Edige formation is the youngest unit of the Some of them, from northwest to southeast, are the palaeotectonic period. It displays well-developed Elmada¤, Tümbek, Sivritepe, Edige, Kaletepe, K›z›lda¤, moderately (20–40°) and steeply (40–80°) dipping Hac›o¤lu and the Bak›rl›k imbricate reverse faults, along bedding planes (Figure 10). In general, tilting increases which various nappes of dissimilar origin, age and near the faulted contacts but decreases by up to 15° away composition are emplaced on each other, and also on the from them (Figure 3). The Edige formation has been youngest palaeotectonic unit, the Turolian Edige deformed into a series of anticlines and synclines, well- formation (Figures 3, 4 & 12). The records and analyses exposed near Edige and Karacahasan villages (Figure 3). of the imbricate reverse faults which redeformed the Stereographic plots of poles to bedding planes clearly Edige formation will be documented separately below. indicate that the Edige formation experienced a phase of Elmada¤ Imbricate Reverse Fault. At a regional scale, NW–SE compression (Figure 11), and was folded at a it is an about 150-km-long, ESE-verging and NNE–SSW- time bracketed by both the Early Pliocene and Late

446 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

b a Station 1

N N

d Station 2 e Station 3 c

Figure 9. (a) Field photograph showing close-up view of the slickensides with slip-lines indicating oblique-slip normal faulting; (b) stereographic plots of slip-plane data measured at station 1 on the Schmidt lower hemisphere net; (c) close-up view of a mesoscopic fault with well- developed and preserved slickenside indicating an oblique-slip normal faulting during sedimentation of the Turolian Edige formation (at station 2 in Figure 3); (d, e) stereographic plots of slip-plane data on the Schmidt lower hemisphere net (data were measured on slickenside of fault arrays within the red beds of the Turolian Edige formation at stations 2 and 3, respectively: Large arrows show localized extension direction). trending contractional structure located between Çank›r› addition, The Elmada¤ imbricate reverse fault is overlain in the northeast and Elmada¤ in the southwest (Figure with angular unconformity by the Plio–Quaternary 1B). It displays a curved to curvilinear trace pattern and neotectonic rocks and sediments outside the study area. dips at an angle of 25° to 80° to the WNW. Only the 10- Therefore, its age must be between the Early Pliocene km-long and NE–SW-trending limited part of the and Late Pliocene. Elmada¤ imbricate reverse fault is included in the study Sivritepe Imbricate Reverse Fault. This approximately area (Figure 3). The Triassic Karakaya Nappe has been 10-km-long, NE–SW-trending and NW-dipping imbricate thrust southeastwards over the Lower Cretaceous reverse fault has a curved to curvilinear trace pattern. Eskiköy nappe, the Cenomanian–Lower Campanian The Sivritepe imbricate reverse fault extends from Anatolian Nappe and the Turolian Edige formation along Sivritepe in the northeast to Karacakaya village in the the Elmada¤ imbricate reverse fault (Figures 3, 12a & southwest and displays a fault plane with well-preserved 13). The youngest rocks disturbed by the reverse faulting and exposed slickensides in places (Figure 8). As are Turolian (Late Miocene–Early Pliocene) in age. In previously explained the Sivritepe imbricate reverse fault

447 NEOTECTONICS OF ANKARA REGION

Figure 10. Field photograph showing general view of moderately dipping red beds comprising the Edige formation (station 4 in Figure 3). was an originally oblique-slip SE-dipping normal fault. Kaletepe Imbricate Reverse Fault. This approximately However, it was reactivated as a reverse fault dipping at 16-km-long, NNE–SSW-trending and WNW steeply 70–85° to the northwest after both the sedimentation (50–80°) dipping high-angle thrust fault with a curved- and folding of the Turolian Edige formation. Ultramafic curvilinear trace extends from Kayadibi village (outside and mafic rocks of the Lower Cretaceous Eskiköy nappe the study area) in the northeast to Kaletepe in the are thrust southeastwards onto the Turolian Edige southwest. Only 6 km of its length is included in the study formation (Figures 8 & 12): the amount of tectonic area (Figure 3). Various undifferentiated lithologies transportation of the Eskiköy nappe on the Edige comprising the Anatolian Nappe are thrust formation is about 0.3-0.8 km, based on the offset along southeastwards on to the red beds of the Edige the tear faults (TF in Figure 3). In the north of the formation, i.e., the red beds dip at 35° northwest Edigekoru district, the Eskiköy nappe, the Edige beneath the Anatolian Nappe (Figures 12b & 14). formation, and the Sivritepe imbricate reverse fault Strike-Slip Faults. Not one isolated strike-slip fault superposing them, are all also overlain with angular inherited from the palaeotectonic period could be mapped unconformity by the Plio–Quaternary Edigekoru in the study area. However, a very widespread formation (Figure 3). Therefore, the timing of the slickenside, indicating a sinistral strike-slip motion with a reverse faulting must be between the Early and Late considerable thrust component, is well-exposed at Station Pliocene. 1 (Figure 3). The strike-slip faulting-induced slickensides

448 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

N (N45o W)

(60 measurements)

Figure 11. Stereographic plots of poles to bedding planes on the Schmidt lower hemisphere net (large arrows indicate localized compression prevailed during the deformation of the Edige formation). occur in a superimposed pattern on both the first phase Neotectonic Structures of oblique-slip normal faulting- and oblique-slip reverse Two major groups of structures characterizing the faulting-induced slickensides on the plane of the Sivritepe neotectonic period in the present study area are: (1) imbricate reverse fault (Figures 15a–c). Kinematic reactivated older faults, and (2) younger faults. The first analyses of slip-plane data obtained from slickensides at group of structures, inherited from the palaeotectonic station 1 precisely revealed a sinistral-strike-slip faulting period, still retain their earlier nature as dextral strike- and a horizontal compression operated in NW–SE slip faults. Older faults occur on both sides of the K›l›çlar direction (Figure 15d). This first phase of contraction river valley around Eski Hisar village and are represented accompanied by the sinistral strike-slip faulting is also by a series of randomly distributed short (0.5–1 km) and strongly evidenced by folding, reverse faulting and minor WNW–ESE-trending fault segments (Figure 4). Older sinistral shear zone dominated by the C-S structures faults cut various lithological components of both the (Figures 11 & 15e). Eskiköy and Anatolian nappes and juxtapose them into Consequently, tight to overturned folds with fault contacts. approximately NE–SW-trending axes, a series of WNW- The second group of structures, represented by dipping imbricate reverse faults and sinistral-strike-slip younger faults formed during the Plio–Quaternary faulting, that accompanied oblique-slip thrust to reverse neotectonic period, are in three categories: (a) NW–SE- faulting, strongly reveal a NW–SE phase of contraction in trending dextral strike-slip faults, (b) NE–SW-trending the Edige area (the Ankara orogenic phase) (Figures 11 & sinistral strike-slip faults, and (c) NNE–SSW to 15d), which appeared after the first phase of extension NNW–SSE-trending oblique-slip normal faults with a (Figure 15f). Finally, this last contractional phase of the considerable amount of strike-slip components based on palaeotectonic regime was replaced by a strike-slip the local distribution pattern of the stress system, in neotectonic regime in the Late Pliocene. σ which the principal stress axis ( 1) is horizontal and

449 NEOTECTONICS OF ANKARA REGION D F(SE) IMBRICATE REVERSE FAULT KALETEPE REVERSE FAULT BAKIRLIK IMBRICATE IMBRICATE REVERSE FAULT EDÝGE -Early Pliocene), ortonian KILIÇLAR RIVER IMBRICATE REVERSE FAULT REVERSE FAULT SÝVRÝTEPE Recent alluvial sediments. i. HACIOÐLU IMBRICATE undifferentiated coloured ophiolitic melange recrystalizied limestone (Jurassic-Early Cretaceous), f. c. fluvio-lacustrine sedimentary sequence (Late T fluvio-lacustrine sedimentary sequence (Late g. red radiolarite block, e. IMBRICATE peridotite-harzburgite-serpentinite, KIZILDAÐ b. REVERSE FAULT ELMADAÐ (b) C m 800 1200 1000 dolerite-gabbro (intrusion), weakly consolidated to loose conglomerate-sandstone (Plio-Quaternary), Triassic Karakaya Nappe, Triassic REVERSE FAULT a. (mostly Cenomanian-Early Campanian matrix), d. h. KIZILDAÐ IMBRICATE B i ? Doyran Str. REVERSE FAULT SÝVRÝTEPE IMBRICATE SET KOCATEPE FAULT KOCATEPE Tümbek Hill Geological cross-sections along the lines A-B, C-D and E-F (see Figures 3 & 4 for locations of sections). REVERSE FAULT abcdef gh ELMADAÐ IMBRICATE Kocatepe str. (c) (a) E(NW) A 900 700 m 1200 1000 Figure 12. (* horizontal and vertical scale are the same)

450 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

Figure 13. Field photograph showing a general view of the Elmada¤ imbricate reverse fault along which the Triassic Karakaya Nappe is emplaced from NW to SE on to the Lower Cretaceous Eskiköy nappe (view to NE).

Figure 14. Field photograph showing general view of the Kaletepe imbricate reverse fault along which the Cenomanian–Lower Campanian Anatolian Nappe is emplaced from NW to SE onto the Turolian Edige formation (view to NW).

451 NEOTECTONICS OF ANKARA REGION 3 s 2 2 s 1 1 f s field photograph showing C-S structure indicating structure C-S showing photograph field the Edige formation). (e) c field photographs showing superimposed slickensides (1. older (b, c) 2 stereographic plots of slip-plane data on the Schmidt lower hemisphere net (f) C 1 S stereographic plots of slip-plane data on the Schmidt lower hemisphere net (data were measured on S S (d) b C e Field photograph showing close-up view of slickensides of sinistral strike-slip fault (Station 1 in Figure 3); a mesoscopic sinistral shear zone along the Sivritepe imbricate reverse fault at station 1 in Figure 3; oblique-slip normal faulting, and 2. younger sinistral strike-slip faulting); formation); Edige the of deformation during prevailed compression localized the indicate arrows large 1; station at 15a Figure (data were measured on Figure 15c2 at station 1; large arrows indicate a localized extension prevailed during sedimentation of d a Figure 15. (a)

452 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

operating in approximately N–S direction, and the σ intermediate axis ( 2) is vertical. This distribution of the stress axes overprinted the Edige formation (Figure 16), and was recently proved once more by the focal mechanism solution of the 2005.07.31, Mw= 5.2 Bala earthquake (HARWARD), sourced from a segment within NE–SW-trending sinistral strike-slip fault zones such as the Balaban and the Küreda¤ fault zones. The Balaban fault zone is a 1–6-km-wide, 60-km-long and NE–SW- trending sinistral simple shear zone located between Tolköy village (11 Km NW of Bala County) in the southwest and the Dutlua¤›l plateau (6 km north of Irmak Town) in the northeast (Koçyi¤it & Deveci, in preparation). The present study area is located approximately 42 km northeast of Bala, and faults exposed in the study area comprise the northeastern extension of both the Balaban and Küreda¤ fault zones. In s1 s3 s2 general, neotectonic faults occur in three fault sets at three localities in the study area. These are the Karagöl Figure 16. Stereographic plots of slip-plane data on the Schmidt fault set, the K›l›çlar fault set and the Hisarköy fault set lower hemisphere net (data were measured at station 4 in (Figures 4, 17 & 18). Figure 3; large arrows indicate a localized N–S compression which has been prevailing since Late Pliocene and governing the strike-slip neotectonic period in the Edige area). Karagöl Fault Set On a regional scale, this structure comprises the north- development of a very young depression, the ‘Balaban easternmost extension of the 3–9-km-wide, 39-km-long plain’. The K›l›çlar fault set is a 0.1–2-km-wide, 5–15- and NE–SW-trending sinistral strike-slip Elmada¤ fault km-long and NNE–SSW-trending simple shear zone zone (Number 20 in Figure 1), which controls the characterized by a few oblique-slip normal faults located southeastern mountain front of the Elmada¤ highlands between K›l›çlar Town in the south and Dutlua¤›l plateau and is located between Beynam Town in the southwest in the north (Figure 18). The K›l›çlar fault set consists of and Elmada¤ County in the northeast. The Karagöl fault closely-spaced, parallel fault segments 5–15 km long. The set is a 1-9-km-long, 3-km-wide and NE–SW-trending longest segment, which was dextrally offset by a short sinistral strike-slip fault set located between Elmada¤ NE–SW-trending dextral strike-slip fault, is the 15-km- County in the northeast and Yerliyurt hill in the southwest long K›l›çlar fault, which displays a steeply sloping and (Figure 17). It consists of closely-spaced, 1–9 km long westward facing fault scarp as a natural response to the and parallel fault segments. Fault-controlled drainage oblique-slip normal motion on it. It tectonically juxtaposes systems such as the Karagöl, Tekke and Otamar streams, the Upper Cretaceous pillowed basalts with Quaternary Plio–Quaternary depressions bounded by faults, linear alluvial sediments. Fault-controlled offset drainage fault traces are common morphotectonic expressions of systems such as the K›l›çlar, Kurba¤al› and Kuﬂçal› rivers, the Karagöl fault set. The longest segment of this set is uplifted and dissected Plio–Quaternary terrace the Elmada¤ fault, which controls southeastern slope of conglomerate, tectonic juxtaposition of both Quaternary the Karagöl stream valley and passes beneath the sediments and pre-Upper Pliocene basement rocks are overpass over the Ankara-Elmada¤-K›r›kkale highway common morphotectonic and geological expressions of (Figure 17). the K›l›çlar fault set (Figure 18).

K›l›çlar Fault Set Hisarköy Fault Set This structure comprises the north-easternmost extension of the Balaban fault zone, which controls This structure is a 1–3-km-wide, 14-km-long and

453 NEOTECTONICS OF ANKARA REGION

N 0 1 Otamar str. km ELMADAÐ STR.

Elmadað overpass

Karagöl str. Elmadað official district

Tekke str.

ELMADAÐ FAULT Tanrý Hill Quaternary sediments 1485 alluvial fan

nonconformity

Yerliyurt Hill Triassic Karakaya Nappe 1454 streams sinistral strike-slip faults with minor normal component

Figure 17. Geological map of the Karagöl fault set.

NNE–SSW-trending oblique-slip normal fault set. It shown by the local (around Elmada¤ County and the comprises the Hisarköy-Edige section of the Balaban fault Balaban depression) concentration of small earthquakes zone and is located between Kuﬂçuali village in the south with magnitudes Ml= 1–4 recorded and analyzed by (outside of the study area) and Edige in the north. The Ergin et al. (2003). Thus, it can be concluded that the northern half of the fault set is within the present study neotectonic regime in the Ankara section of the ‹AESZ is area, and consists of six parallel to sub-parallel, closely- predominantly characterized by strike-slip faulting which spaced, various-sized and steeply dipping oblique-slip commenced in Late Pliocene time. normal fault segments with a considerable sinistral strike- slip component (Figure 4). Fault-controlled offset Discussion and Conclusion drainage systems such as the Kocatepe and Balaban rivers, and tectonic juxtaposition of various lithological The intra-continental convergence and the development components of both the Anatolian and Eskiköy nappes history of the ‹AESZ lasted throughout the Oligocene–Miocene and Early Pliocene time intervals after and the Turolian Edige formation with each other and the Late Eocene final collision and total subduction of the with the Quaternary alluvial sediments are common intervening oceanic lithosphere between the Sakarya morphotectonic and geological expressions of the Continent in the north and the Menderes-Tauride Hisarköy fault set (Figure 4). platform to K›rﬂehir block in the south in the Ankara Most fault segments comprising the fault sets region (Koçyi¤it 1991a; Koçyi¤it et al. 1995, 2003). As described briefly above are also seismically active, as a result of the Late Eocene–Early Pliocene intra-

454

A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

PERIOD

ONIC NEOTECT PERIOD ONIC ALEOTECT P PERIOD TECTONIC regime REGIME TECTONIC strike-slip to contractional ctonic period in the Edige area. compressional- extensional regime GEOLOGICAL STRUCTURES normal faults ANGULAR UNCONFORMITY strike-slip fault strike-slip regime strike-slip faults thrust to reverse faults folds ANGULAR UNCONFORMITY strike-slip faulting thrust to reverse faulting folding by

* sedimentation of Edige formation under the control of normal faulting

* deformation and * uplift of Edige formation * sedimentation of Edigekoru formation under the control of strike-slip faulting

Summary of major processes, events, geological structures, tectonic regimes, and transition from palaeotectonic period to neote PLIOCENE EARLY QUATERNARY

LATE MIOCENE - MIOCENE LATE

LATE PLIOCENE - PLIOCENE LATE (TUROLIAN) PRE - TIME EVENTS AND TECTONIC PROCESSES MIOCENE Table 1.

455 NEOTECTONICS OF ANKARA REGION

One type locality where these processes, events, N short-term phases of both extension and contraction and 0 2 Dutluaðýl Plateau related structures are well-recorded and preserved is the km Edige area (Figure 3 & Table 1). The intra-continental convergence, dominated by the contractional tectonic regime, was locally interrupted by a short-term phase of WNW–ESE extension in the Edige area, recorded by the deposition of the Turolian Edige formation (Figures 9, 15 Eskikayadibi f & Table 1). Towards the end of the Edige formation sedimentation, the phase of extension was replaced by a short-term phase of NW–SE contraction (Ankara Orogenic Phase), which deformed, uplifted and Yenikayadibi incorporated the Edige formation into the Ankara KILIÇLAR FAULT foreland fold-imbricate thrust to reverse fault zone by folding, thrust to reverse faulting and finally strike-slip Kurbaðalý R. Irmak KAYADÝBÝ FAULT faulting during the Early Pliocene and/or a time slice Alipýnar str. between the Early and Late Pliocene (Figures 11, 12,

Kuþçalý R. 15a–e & Table 1). The long-term and regional intra- continental convergence continued till the neotectonic period, dominated by an active strike-slip faulting. The neotectonic period is evidenced by an angular unconformity, which underlies the undeformed (nearly flat-lying) Edigekoru formation and seals the entire intensely deformed (tilted, folded, cleaved and faulted) Kýlýçlar R. rock assemblages and structures of the Ankara foreland fold-imbricate thrust to reverse fault zone. The active Recent alluvial strike-slip faulting caused by a new phase of compression KILIÇLAR FAULT sediments alluvial fan is evidenced by both the very young deformational terrace records in the Edige Formation (Figure 16) and the focal Kýlýçlar conglomerate mechanism solutions of recent earthquakes (e.g., pre-Upper Pliocene basement rocks 2005.07.31, Mw= 5.2 Bala earthquake) sourced from oblique-slip normal the fault segments of the Elmada¤, Balaban and the fault with strike-slip component Küreda¤ fault zones. The strike-slip neotectonic regime strike-slip fault has been extant under the control of the approximately N–S principal stress since the Late Pliocene (Figure 16 & Figure 18. Geological map of the K›l›çlar fault set. Table 1). Thus, it can be concluded that the last palaeotectonic period, characterized by a contractional continental convergence, the Ankara section of the ‹AESZ tectonic regime, was replaced by the strike-slip became emergent, while at the same time the whole of neotectonic regime, i.e., the neotectonic period, which the pre-Upper Pliocene rock assemblages were was initiated in the Ankara region in the Late Pliocene. tectonically stacked up in a broad foreland fold-imbricate thrust to reverse fault zone complex characterized by both the Ankara forced folds and SSE-verging imbricate Acknowledgement thrusts. This long-term convergence also led to crustal The authors would like to express their sincere thanks to shortening, uplift and over-thickening, in which local anonymous reviewers whose comments have greatly failure was evidenced by the intervening short-term improved an earlier version of the present text. John A. phases of extension recorded in the fluvio-lacustrine sedimentary systems. Winchester edited the English of the final text.

456 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

References

ACH,JA. 1982. The Petrochemistry of the Ankara Volcanics, Central ERG‹N, M., ÖZALAYBEY, S., AKTAR, M., B‹ÇMEN, F., TAPIRDAMAZ, C., YÖRÜK, Turkey. MSc Thesis, State University of New York at Albany, USA. A., TARANCIO⁄LU, A., BELGEN, A., YÜCE, H., ERKAN, B. & YAKAN, H. 2003. Kazan-Trona Yata¤ının Depremselli¤i Sonuç Raporu [Final AKYÜREK, B. B‹LG‹NER, B., AKBAfi, B., HEPfiEN, N., PEHL‹VAN, fi., SUNU, O., SOYSAL, Y., DA⁄ER, Z., ÇATAL, E., SÖZER‹, B., YILDIRIM, H. & Report on the Seismicity of Kazan Trona Prospect]. Türkiye HAKYEMEZ,Y. 1984. Ankara-Elmada¤-Kalecik dolayının jeoloji Bilimsel ve Teknik Arafltırma Kurumu, Marmara Arafltırma özellikleri [Geological characteristics of Ankara-Elmada¤-Kalecik Merkezi, Gebze-Kocaeli, Project no. 5037101 [in Turkish].

region]. Jeoloji Mühendisli¤i Dergisi 20, 21–46 [in Turkish with EROL, O. 1951. Ayafl Da¤ları ve Mürted Ovasının Kuzey Bölümü English abstract]. Hakkında Rapor [A report on the Ayafl Mountains and Northern ALTINER, D., KOÇY‹⁄‹T, A., FARANACCI, A., NICOSSIA, U. & CONTI, M.A. 1991. Part of Mürted Plain]. General Directorate for Mineral Research Kuzeybatı Anadolu güneyinin Jura-Erken Kretasede paleoco¤rafik and Exploration Institute (MTA) Report no. 2456 [in Turkish, evrimi [Jurassic–Early Cretaceous palaeogeographic evolution of unpublsihed]. southern part of northwest Anatolia]. Do¤a Türk Yerbilimleri EROL, O. 1954. Ankara ve Civarının Jeolojisi Hakkında Rapor [A Report Dergisi, 1, 1–9. on the Geology of Ankara and Its Surrounings]. General ALTINER, D. & KOÇY‹⁄‹T, A. 1992. Kuzeybatı Anadolu güneyinin Jura- Directorate for Mineral Research and Exploration Institute (MTA), Erken Kretase’de paleoco¤rafik evrimi [Palaeogeographic Report no. 2491 [in Turkish, unpublished]. evolution of south of NW Anatolia during Jurassic–Early Cretaceous time]. Do¤a Türk Yerbilimleri Dergisi 1, 1–9 [in EROL, O. 1955. Köro¤lu-Iflıkda¤ları volkanik kütlesinin orta bölümleri ile Turkish with English abstract]. Beypazarı-Ayafl arasındaki Neojen havzasının jeolojisi hakkında rapor [A Report on the Central Part of Köro¤lu-Iflıkda¤ları ALTINER, D. & KOÇY‹⁄‹T, A. 1993. Third remark on the geology of Volcanic Body and Neogene Basin between Beypazarı and Ayafl]. Karakaya Basin: an Anisian megablock in northern central General Directorate for Mineral Research and Exploration Anatolia: Micropaleontologic, stratigraphic and tectonic Institute (MTA) Report no. 2279 [in Turkish, unpublished]. implications for the rifting stage of Karakaya basin, Turkey. Revue de Paléogiologie 12, 1–17. EROL L, O. 1980. Türkiye’de Neojen ve Kuvaterner aflınım dönemleri, bu dönemlerin aflınım yüzeyleri ile yaflıt (korelan) tortullara göre ALTINER, D., ÖZKAN-ALTINER, S. & KOÇY‹⁄‹T, A. 2000. Late Permian foraminiferal biofacies belts in Turkey: palaeogeographic and belirlenmesi [Neogene and Quaternary erosional stages in Turkey, tectonic implications. In: BOZKURT, E., WINCHESTER, J.A. & PIPER, and identification of these stages with correlative sediments]. J.D.A. (eds), Tectonics and Magmatism in Turkey and the Jeomorfoloji Dergisi C8, 1–40 [in Turkish with English abstract].

Surrounding Area. Geological Society, London, Special GÖKTEN, E., KAZANCI, N. & ACAR, ﬁ. 1988. Stratigraphy and tectonics of Publications 173, 83–96. Late Cretaceous–Pliocene series in the north-west of Ankara BAILEY, E.B. & MCCALLIAN, W.C. 1953. The Ankara mélange and the between Ba¤lum and Kazan. Mineral Research and Exploration Anatolian thrust. Royal Society of London, Philosophical Institute of Turkey (MTA) Bulletin 108, 69–81 [in Turkish with Transactions 62, 403–442. English abstract].

BATMAN, B. 1978. Geological evolution of northern part of Haymana GÖKTEN, E., ÖZAKSOY, V. & KARAKUﬁ, V. 1996. Tertiary volcanics and region and study of mélange in the area, I: Stratigraphic units. tectonic evolution of the Ayaﬂ-Güdül-Çeltikçi region. International Hacettepe University Bulletin of Earth Sciences 4, 95–124. Geology Review 38, 926–934.

B‹NGÖL, E., AKYÜREK, B. & KORKMAZER, B. 1973. Biga yarımadasının GÖRÜR, N., OKTAY, F., SEYMEN, ‹. & fiENGÖR, A.M.C. 1984. Paleotectonic jeolojisi ve Karakaya formasyonunun bazı özellikleri [Geology of evolution of the Tuzgölü basin complex: sedimentary record of a Biga Peninsula and characteristics of Karakaya formation]. Neotethyan closure. In: DIXSON, J.E. & ROBERTSON, A.H.F. (eds), Cumhuriyet’in 50. yılı Yerbilimleri Kongresi Tebli¤leri, The Geological Evolution of the Eastern Mediterranean. Proceedings, 70–77 [in Turkish with English abstract]. Geological Society, London, Special Publications 17, 467–482. BOZKURT, E., KOÇY‹⁄‹T, A., WINCHESTER, J.A., HOLLAND, G. & BEYHAN,A. KAPLAN, T. 2004. Neotectonics and Seismicity of the Ankara Region: A 1999. Petrochemistry of the Oyaca-Kedikayası (Ankara) dacites: Case Study in the Urufl Area. MSc Thesis, Middle East Technical evidence for the post-collisional tectonic evolution of north- University, Engineering Faculty, Department of Geological central Anatolia, Turkey. Geological Journal 34, 223–231 Engineering [Unpublished]. DEM‹RC‹,C. 2000. Structural Analysis in Beypazarı-Ayafl-Kazan-Peçenek Area, NW of Ankara (Turkey). PhD Thesis, Middle East Technical KAYMAKCI,N. 2000. Tectono-stratigraphical Evolution of the Çankırı University, Engineering Faculty, Department of Geological basin (central Anatolia, Turkey). PhD Thesis, Geologica Engineering [unpublished]. Ultraiectina, No 190, Utrecht University Faculty of Earth Sciences, The Netherland, ISBN 90-5744-047-4. DOKUZ, A. & TANYOLU, E. 2006. Geochemical constraints on the provenance, mineral sorting and subaerial weathering of Lower KAZANCI, N. & GÖKTEN, E. 1988. Lithofacies features and tectonic Jurassic and Upper Cretaceous clastic rocks of the Eastern environments of the continental Paleocene volcanoclastics in Pontides, Yusufeli (Artvin), NE Turkey. Turkish Journal of Earth Ankara region. METU Journal of Pure and Applied Sciences 21, Sciences 15, 181–209. 271–282.

457 NEOTECTONICS OF ANKARA REGION

KELLER, J., JUNG, D., ECKHARDT, F.J. & KREUZER, H. 1992. Radiometric KOÇY‹⁄‹T, A. ÖZKAN, S. & ROJAY, B.F. 1988. Examples from the forearc ages and Chemical characterization of Galatean andesite massif, basin remnants at the active margin of northern Neo-Tethys: Pontus, Turkey. Acta Vulcanologica 2, 267–276. Development and emplacement ages of the Anatolian Nappe, Turkey. METU, Journal of Pure and Applied Sciences 21, KOÇY‹⁄‹T,A. 1987. Hasano¤lan (Ankara) yöresinin tektono-stratigrafisi: 183–210. Karakaya Orojenik Kuﬂa¤ı’nın evrimi [Tectono-stratigraphy of Hasano¤lan (Ankara) region: evolution of Karakaya Orogenic KOÇY‹⁄‹T, A., TÜRKMENO⁄LU, A., BEYHAN, A., KAYMAKCı, N. & AKYOL, E. Zone]. Hacettepe Üniversitesi Yerbilimleri Dergisi 14, 269–293. 1995. Post- Collisional tectonics of Eskiﬂehir-Ankara-Çankırı [in Turkish with English abstract]. segment of ‹zmir-Ankara-Erzincan Suture Zone (IAESZ): Ankara orogenic phase. Turkish Association of Petroleum Geologists KOÇY‹⁄‹T, A. 1991a. An example of an accretionary forearc basin from Bulletin 6, 69–86. northern Central Anatolia and its implications for the history of subduction of Neo-Tethys in Turkey. Geological Society of KOÇY‹⁄‹T, A., WINCHESTER, J.A., BOZKURT, E., HOLLAND, G. & BEYHAN,A. America Bulletin 103, 22–36. 2003. Saraçköy Volcanic suite: implications for the subductional phase of arc evolution in the Galatean Arc Complex, Ankara, KOÇY‹⁄‹T, A. 1991b. Changing stress orientation in progressive Turkey. Geological Journal 38, 1–14. intracontinental deformation as indicated by the Neotectonics of the Ankara Region (NW Central Anatolia). Turkish Association of MOORE,J.C. 1979. Variation in strain and strain rate during Petroleum Geologists Bulletin 3, 43–55. underthrusting of trench deposits. Geology V, 193–223.

KOÇY‹⁄‹T, A. 1991c. First Remarks on the Geology of the Karakaya MOORE, J.C. & WHEELER, R.L. 1978. Structural fabric of a mélange Basin: Karakaya orogen and pre-Jurassic nappes in eastern Kodiak islands, Alaska. American Journal of Science 278, Pontides, Turkey. Geologica Romana 27, 3–11. 739–765.

KOÇY‹⁄‹T,A. 1992. Southward-vergent imbricate thrust fault zone inMOORE, G.F. & KARIG, D.E. 1980. Structural Geology of Nias island, Yuvaköy: a record of the latest compressional event related to the Indonesia: implications for subduction zone tectonics. American collisional tectonic regime in Ankara-Erzincan Suture Zone. TABG Journal of Science 280, 193–223. Bulletin 4, 11–118 NEBERT,K. 1958. ‹ç Anadolu’nun en genç jeolojik-tektonik olayı KOÇY‹⁄‹T,A. 2003. Orta Anadolu’nun genel tektonik özellikleri ve hakkında bir etüd: Ankara vilayetinin (Kayı-Bucak) civarındaki depremselli¤i [General tectonic characteristics and seismicity of Waallachien orojenez safhasının ispatı [Investigation of the Ankara region]. Turkish Association of Petroleum Geologists youngest geologic-tectonic event in central Anatolia: Proof of Bulletin, Special Publication 5, 1–26 [in Turkish with English Wallachien orogenic phase around Ankara (Kayı-Bucak)]. Mineral abstract]. Research and Exploration Institute of Turkey (MTA) Bulletin 50, 16–29 [in Turkish with English abstract]. KOÇY‹⁄‹T, A. & ALTINER, D. 1990. Stratigraphy of the Halılar (Edremit- Balıkesir) area: implications for the remnant Karakaya Basin and NELSON, K. 1982. A suggestion for origin of mesoscopic fabric in its diachronic closure. In: SAVAﬁÇıN, M.Y. & ERONAT, A.H. (eds), accretionary mélange based on features observed in the Chrystalls Proceedings of International Earth Sciences Congress on Aegean Beach Complex, South Island, New Zealand. Geological Society of Regions, 1–6 October, 1990, ‹zmir, 339–352. America Bulletin 93, 625–634.

KOÇY‹⁄‹T, A. & ALTINER, D. 2002. Tectonostratigraphic evolution of the NORMAN, T. 1972. Stratigraphy of the Upper Cretaceous–Lower Tetriary North Anatolian Paleorift (NAPR): Hettangian–Aptian passive sequence in Ankara-Yahflihan region. Geological Society of Turkey continental margin of the northern Neotethys, Turkey. Turkish Bulletin XV, 180–276. Journal of Earth Sciences 11, 169–191. OKAN, Y. 1982. Elmada¤ formasyonunun (Ankara) yaflı ve alt bölümleri KOÇY‹⁄‹T, A., ALTINER, D., FARINACCI, A., NICOSIA, U. & CONTI,S. 1991b. [Age and subunits of Elmada¤ formation (Ankara)]. Geological Late Triassic–Aptian evolution of the Sakarya divergent margin: Society of Turkey Bulletin 25, 83–92 [in Turkish with English implications for the opening history of the northern Neo-Tethys, abstract]. in northwestern Anatolia, Turkey. Geologica Romana, XXVII, OKAY, A. 1984. Kuzeybatı Anadolu’da yer alan metamorfik kuflaklar 81–99. [Metamorphic belts of northwest Anatolia]. Ketin Simpozyumu, KOÇY‹⁄‹T, A., D‹R‹K, K., ROJAY, B.F., ÖZCAN, E., KAYMAKCı, N. & ÖZÇEL‹K,Y. Proceedings, 83–92 [in Turkish with English abstract]. 1991a. ‹negöl-Bilecik-Bozüyük Arasında Kalan Alanın Jeolojik OKAY, A. & MOSTLER,H. 1994. Carboniferous and Permian radiolarite Etüdü [Geology of ‹negöl-Bilecik-Bozüyük Region]. ODTÜ-TPAO blocks from the Karakaya Complex in northwest Turkey. Turkish Uygulamalı Arafltırmalar Projesi no. 90-03-09-01-05 [in Turkish, Journal of Earth Sciences 3, 23–28. unpublished]. OKAY, A., TANSEL, ‹. & TÜYSÜZ, O. 2001. Obduction, subduction and KOÇY‹⁄‹T, A. & LÜNEL,T. 1987. Geology and tectonic setting of Alcı collision as reflected in the Upper Cretaceous–Lower Eocene region, Ankara. METU, Journal of Pure and Applied Sciences 20, sedimentary record of western Turkey. Geological Magazine 138, 35–57. 117–142.

458 A. KOÇY‹⁄‹T & ﬁ. DEVEC‹

ROJAY, B. & SÜZEN, L. 1997. Tectonostratigraphic evolution of the SEYMEN, ‹. 1975. Kelkit Vadisi Kesiminde Kuzey Anadolu Fay Zonunun cretaceous dynamic basin on accretionary ophiolitic mélange Tektonik Özelli¤i [Neotectonic Characteristics of the North prism, SW of Ankara region. Turkish Association of Petroleum Anatolian Fault Zone in Kelkit Valley]. PhD Thesis, ‹stanbul Geologists Bulletin 9, 1–12. Technical University, Mining Faculty [in Turkish with English abstract]. SANER, S. 1980. The Paleogeographical interpretation of the Mudurnu- Göynük basin based on the depositional features of the Jurassic ﬁENGÖR, A.M.C. & YILMAZ, Y. 1981. Tethyan evolution of Turkey: a plate and later ages. Geological Society of Turkey Bulletin 23, 39-52. tectonic approach. Tectonophysics 75, 181–224.

SARAÇ, G. 1994. Ankara Yöresindeki Karasal Neojen Çökellerinin TOKAY, M., LÜNEL, A.T. & KOÇY‹⁄‹T, A. 1988. Geology and Petrology of Rhinocerotidae (Mammalia-Perissodactyla) Biyostratigrafisi ve the Gökdere stock of the Orhaniye Syenite, Ankara. METU, Paleontolojisi [Rhinocerotidae (Mammalia-Perissodactyla) Journal of Pure and Applied Sciences 21, 1–37. Biostratigraphy and Palaeontology of Neogene Continental TOPRAK, V., SAVAfiÇIN, Y., GÜLEÇ, N. & TANKUT, A. 1996. Structure of the Sediments Around Ankara]. PhD Thesis, Ankara University, Galatean volcanic province. International Geology Review 38, Department of Geological Engineering [in Turkish with English 747–758. abstract, unpublished] TÜYSÜZ, O. & Y‹⁄‹TBAfi,E. 1994. The Karakaya basin: a palaeotethyan SARAÇ,G. 2003. Türkiye Omurgalı Fosil Yatakları [Mammalian Fossil marginal basin and its age of opening. Acta Geologica Hungarica Localities in Turkey]. General Directorate of Mineral Research and 75,181–241. Exploration Institute (MTA), Scientific Report no. 10609 [in Turkish, unpublished]. TÜYSÜZ, O., DELLALO⁄LU, A.A. & TERZ‹O⁄LU, N. 1994. A magmatic belt within the Neo-Tethyan suture zone and its role in the tectonic SAYIN, N. 1985. Geology and Petrography of the Northeast of evolution of northern Turkey. Tectonophysics 243, 173–191. Karacahasan, Elmada¤ (Ankara-Turkey). MSc Thesis, Middle East Technical University, Department of Geological Engineering WILSON, M., TANKUT, A. & GÜLEÇ, N., 1997. Tertiary volcanism of the [unpublished]. Galatia province, North-west central Anatolia, Turkey. Lithos 42, 105–121. SEY‹TO⁄LU, G., KAZANCI, N., KARAKUfi, K., FODOR, L., ARAZ, H. & KARADEN‹ZL‹, L., 1997. Does continuous Compressive Tectonic regime Exist During Late Paleogene to Late Neogene in NW Central Anatolia, Turkey? Preliminary observations. Turkish Journal of Earth Sciences 6, 77–83.

Received 18 January 2007; revised typescript received 11 February 2008; accepted 19 February 2008

459