Ankara Orogenic Phase, Its Age and Transition From ......Gerek katman kutuplar›n›n stereografik izdüﬂümleri, gerekse formasyon içinde ve formasyon kenar faylar› boyunca

Ankara Orogenic Phase, Its Age and Transition FromThrusting-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 Tectonicsand 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 majorgroups of contractional structures, namely the Ankara forced folds-monoclines and the southward-verging forelandfold-imbricate thrust to reverse fault zone (AFITFZ). In the Ankara region, one of the areas where the variousphases 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 deformedin the last phase of the palaeotectonic period (the Ankara orogenic phase) is the Edige formation. It consists of afluvio-lacustrine sedimentary sequence mainly comprising basal conglomerate, shale, marl and a clayey limestonealternation 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 normalfaulting, in which the localized extension prevailed in approximately WNW–ESE direction. This first phase ofextension was later replaced by a contractional tectonic regime and related successive and short-term phases ofdeformation such as folding, thrust to reverse faulting and finally strike-slip faulting which interruptedsedimentation of the Edige formation and deformed it. Both the stereographic plots of poles to bedding planes andthe palaeostress analyses of slip-plane data recorded in the Edige formation and along its margin-boundary faultsindicate that maximum horizontal stress operated in NW–SE direction during the phase of contraction. Finally, thislast contractional tectonic regime (Ankara Orogenic Phase) was replaced by a strike-slip neotectonic regime. Thisis evidenced by an angular unconformity, which separates the underlying intensely deformed older rockassemblages 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 LatePliocene, has continued since that time under the control of active strike-slip faulting caused by a horizontalapproximately N–S compression. This is indicated by three sets of approximately N–S strike-slip faults, namely theElmada¤, K›l›çlar and Hisarköy fault sets in the study area, which comprise northeastern continuations of theElmada¤, 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 northeasternextensions, 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›nEgemen 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 faykufla¤›d›r (AKBTFK). Ankara bölgesinde çeflitli deformasyon evrelerinin ve ilgili yap›lar›n en iyi korundu¤u veyüzeyledi¤i yerlerden birisi Edige (Elmada¤) ve çevresidir. Edige, Ankara ‹lin’in 48 km do¤u-güneydo¤usundayeral›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¤inegöre Turoliyen (MN 11) (Geç Tortoniyen–Erken Pliyosen) yafll› olan formasyon taban çak›ltafl›, fleyil, marn ve killikireçtafl› ardafl›m›yla temsil edilir. Edige formasyonu, normal faylanma ile karakterize edilen geniflleme türütektonik rejimin denetiminde çökelmifltir ve çökelim s›ras›ndaki yerel geniflleme yönü yaklafl›k BKB–DGD dur. Dahasonra, bu ilk evre geniflleme rejimi, s›k›flma-daralma türü tektonik bir rejim ve bu rejim ile ilgili k›sa sürelideformasyon 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 kesintiyeu¤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 eskigerilimanalizi, bu s›k›flma-daralma evresi s›ras›nda, en büyük s›k›flman›n KB–GD yönünde etkin oldu¤unu göstermifltir. Bu

Turkish Journal of Earth Sciences (Turkish J. Earth Sci.), Vol. 17, 2008, pp. 433–459. Copyright ©TÜB‹TAKFirst published online 22 February 2008

433

NEOTECTONICS OF ANKARA REGION

434

Introduction

Subduction, collision and suturing are progressivetectonic events occurring at active convergent plateboundaries and lasting for a long period of time. Based ontheir ages, these events can be classified as pre-collisional,syn-collisional or post-collisional events. They determinesite, size and nature of the suture zones on the dynamicearth. One of the major compressional palaeotectonicstructures in northern Turkey is the ‹zmir-Ankara-Erzincan suture zone (‹AESZ) (fiengör & Y›lmaz 1981)extending from ‹zmir in the west and trending eastwardspast Ankara, Erzincan towards the Caucasus Mountainsfurther to the east (Figure 1A). The ‹AESZ is dominatedby a polygenetic assortment of stacked and imbricatethrust fault-bounded zones made up of accreted andobducted components accumulated in both trench andfore-arc settings, which evolved during northerly obliquesubduction and diachronous closure of the northernNeotethyan Ocean (Görür et al. 1984; Koçyi¤it 1991a).Collision and suturing in the ‹AESZ is diachronous, i.e.,they started in the Maastrichtian and continued till theEarly Miocene at different locations along the suture zone(Seymen 1975; Saner 1980; fiengör & Y›lmaz 1981;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).

In general, sutures are geologically very complicatedtectonic domains, due to superimposition of pre-, syn-and post-collisional tectonic events and related structures.Therefore, observing well-preserved structures and rocksequences within the sutures is of great importance inbetter understanding their tectonic settings andevolutionary histories. One of the type localities wherethe post-collisional structures are particularly well-preserved and exposed is the Ankara section of the ‹AESZ

(Figure 1B). However, most previous work carried out inthe Ankara section of ‹AESZ dealt only with the pre- andsyn-collisional characteristics of the suture zone (Erol1954; fiengör & Y›lmaz 1981; Akyürek et al. 1984; Say›n1985; Koçyi¤it 1987, 1991a; Gökten et al. 1988; Tüysüzet al. 1994; Toprak et al. 1996; Rojay & Süzen 1997;Kaymakc› 2000; Koçyi¤it et al. 2003). In contrast,detailed and field-based previous studies of both the post-collisional and neotectonic characteristics of the Ankarasection of ‹AESZ are very limited, and hence there aremany geological problems which are still disputed byauthors (Nebert 1958; Erol 1980; Koçyi¤it 1991b,1992, 2003; Koçyi¤it et al. 1995; Gökten et al. 1996;Seyito¤lu et al. 1997; Demirci 2000; Kaplan 2004).Some significant unresolved geological problems include:(1) what is the number, nature and duration(s) of thetectonic regimes dominating the post-collisionalpalaeotectonic period?; (2) how long have these regimesprevailed?; (3) what are the post-collisional geologicalstructures?; and (4) when were the strike-slipneotectonic regime initiated in the Ankara region? Thepresent paper aims to bring plausible solutions for thesegeological problems in the light of recent field data andrelated literature.

Regional Tectono-stratigraphical Setting

Allochthonous, para-autochthonous and autochthonousrock assemblages are generally well-exposed in theAnkara region. Based on their occurrence ages, they are,from oldest to youngest, classified into eight categories:(1) pre-Triassic Lalahan nappe, (2) Triassic KarakayaNappe, (3) Upper Hettangian–Lower Campanian AnkaraGroup, (4), Lower Campanian Anatolian Nappe, (5)Middle Campanian–Middle Eocene Memlik Group, (6)Upper Campanian–Lower Pliocene K›z›lcahamam

enson s›k›flma-daralma türü eski tektonik rejim, daha sonra do¤rultu at›ml› yeni bir tektonik rejim ile yerde¤ifltirmifltir. Bu de¤iflim, altta yeralan ve ayn› zamanda Edige formasyonunu da içeren ye¤ince deformasyongeçirmifl 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 aktifdo¤rultu at›ml› faylanma denetiminde Geç Pliyosen’den günümüze sürmektedir. Bu durum, Balaban, Elmada¤ veKüreda¤ fay zonlar›n›n kuzeydo¤u uzant›lar›n› oluflturan ve inceleme alan› içinde yer alan Elmada¤, K›l›çlar veHisarköy fay tak›mlar›yla belirginlik kazan›r. Çünkü, enson oluflan 5.2 (Mw) büyüklü¤ündeki 31 Temmuz 2005Bala depremi Balaban fay zonundan kaynaklanm›fl olup, ayr›ca küçük deprem episant›rlar› Elmada¤, K›l›çlar veHisarköy fay tak›mlar› üzerinde yo¤unlaflarak, bu fay tak›mlar›n› oluflturan do¤rultu at›ml› fay segmentlerindenbaz›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

A. KOÇY‹⁄‹T & fi. DEVEC‹

435

� � � � � � � � � � �

��

��

��

�

�

�!��"#

��

��

#��

��$��

��%�&�'��#��()

��

#

�

��

�

��

��

��

��

*�+��

,��)-+

��'��$�+��

.��.

�/,��

��.�#��

��!�

0��$��%�*�+��)-+

"1

�

*� "2

"3

"4

"5

*.

6��

5

"7

13

""##

��8��

46

9

#�+:�8��%�

6�+%�'��

2

��%'��

7

"

��.��*� � �� 0 �� .�;

�+�&

"< "9

��)-+��

��

"=

�%��+�)�

=

*

��>��)�%8%�(�'��

� ��

��

=1�)�

�

$

(

�

�

�

��

��

#�+��

#��

�,��/��,��.� ��

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 SutureZone, 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– Ayaflmonocline and reverse fault, 7– P›naryaka folds, 8– Baflbereket (BB) monocline and reverse fault, 9– Kazanmonocline 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 thrustfault, 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 theKarakaya orogenic belt (KO), Ar– Artvin.

magmatic arc complex, (7) Oligo–Miocene fluvio-lacustrine and volcano-sedimentary sequences, and (8)Plio–Quaternary neotectonic units (Erol 1951, 1954,1955; Norman 1972; Batman 1978; Akyürek et al.1984; Koçyi¤it 1987, 1991a; Koçyi¤it & Lünel 1987;Koçyi¤it et al. 1988; Kazanc› & Gökten 1988; Gökten etal. 1988; Koçyi¤it et al. 2003).

The Lalahan Nappe, a product of the Hercynianorogeny, occurs in two NE-trending belts 2–15 km widecharacterized by polyphase metamorphic rocks intrudedby metadiabase and serpentinized basaltic dykes. Theyconsist mostly of metabasic rocks (albite-diabase, spiliticbasalt, basalt, volcanic breccia and tuff), amphibolite,greenschist, meta-ultramafic rocks, phyllite, calc-schist,graphite schist, marble, quartzite and metaclastic rocks.It is thrust southeastwards on to the younger KarakayaNappe. The Karakaya Nappe occurs in a NE-trending belt3–18 km wide, and 60 km long in the Ankara region. Itis a tectono-sedimentary chaotic mixture of blocks ofhigh- to low-grade metamorphic rocks, mafic toultramafic rocks, deep- and shallow-water carbonates ofCarboniferous–Triassic age, litharenites and radiolariancherts set in a slightly metamorphosed but intenselysheared litharenitic to shaly matrix. The Karakaya Nappeis a product of the Karakaya orogeny and it is Middle toLate Triassic in age based on fossils identified in its matrix(Okan 1982; Koçyi¤it 1987; Alt›ner & Koçyi¤it 1993).The Karakaya Nappe is also thrust southeastwards ontothe younger Anatolian Nappe (Koçyi¤it 1987; Koçyi¤it etal. 1995). The Ankara Group occurs in various-sized anddiscontinuous outcrops in Ankara region. In a normalstratigraphical position, it overlies with an angularunconformity the Lalahan and the Karakaya nappes, andconsists, from bottom to top, of six different lithofaciessuch as fluvial basal conglomerate, shallow-marine clasticswith the intercalation of widespread Rosso-Ammoniticofacies, open shelf to slope carbonates, fine-grained deep-marine sedimentary facies, sedimentary mélange andagain deep-marine shale and mudstone (Koçyi¤it 1991a).Based on its very rich fossil content, the Ankara Group islate Hettangian–early Campanian in age (Koçyi¤it 1987,1991a). At the top, the Ankara Group is overthrust bythe Anatolian Nappe (Koçyi¤it 1991a). The AnatolianNappe, a product of the Alpine orogeny, occurs inwidespread but variably-sized and discontinuous outcropsalong the ‹AESZ. It is dominated by theCenomanian–Lower Campanian coloured ophiolitic

mélange or subduction complex accreted at the south-facing northern active margin of the northern NeotethyanOcean (Koçyi¤it 1991a). It displays both normalstratigraphical and tectonic contact relationships withrock assemblages in age ranging from Triassic to EarlyPliocene (Koçyi¤it 1987, 1991a; Koçyi¤it et al. 1995).The Memlik Group is an approximately 1.5 km thicksedimentary infill deposited in the north-northwesternpart of the Haymana-Polatl› accretionary fore-arc basin,which was one of diagnostic structures of the northernNeotethyan Ocean. It consists of a coarsening-upwardsequence of Middle Campanian–Middle Eocene age(Koçyi¤it 1991a). At the bottom, the Memlik Groupdisplays a stratigraphically conformable boundaryrelationship with the ophiolitic mélange of the AnatolianNappe, although it is overlain with an angularunconformity by the post-collisional fluvio-lacustrinesedimentary and volcano-sedimentary sequences ofOligocene–Early Pliocene age at the top. This ≥ 1-km-thick continental sequence consists mostly of fluvial redbeds, coal seam-bearing lacustrine shales, carbonates toevaporates, and andesitic-basaltic volcanics andvolcaniclastics (Erol 1951, 1954, 1955; Koçyi¤it et al.2003; Kaymakc› 2000). One of the most widespread anddiagnostic rock assemblages, recording northerlysubduction of the northern Neotethyan Ocean floor in theAnkara region, is the K›z›lcahamam magmatic arccomplex (Figure 1B). Previously and erroneously namedthe ‘Galatean Arc Complex’ using the national name of anancient civilization (Galatia) by Koçyi¤it et al. (2003), inthis paper, it is renamed the K›z›lcahamam magmatic arccomplex, using the geographical name (K›z›lcahamamCounty) of the type locality where it is well-exposed. TheK›z›lcahamam magmatic arc complex evolved in threestages, namely the pre-, syn- and post-collisional stages,to be an intra- and back-arc settings comprising thesouth-facing northern active margin of the northerlysubducting northern Neotethyan Ocean (Koçyi¤it 1991a;Koçyi¤it et al. 2003). It consists mainly of calc-alkalineand alkaline volcanic rock assemblages (trachyte, dacite,andesite, basalt and their pyroclasts up to 2.5 km totalthickness) ranging in age from Middle Campanian to EarlyPliocene (Ach 1982; Koçyi¤it & Lünel 1987; Tokay et al.1987; Keller et al. 1992; Wilson et al. 1997; Bozkurt etal. 1999; Koçyi¤it et al. 2003). The K›z›lcahamammagmatic arc complex accompanies LateCretaceous–Early Tertiary fore-arc marine sedimentationand Oligo–Miocene continental sedimentation recording


436

the subductional-, collisional- and post-collisionalevolutionary history of the northern Neotethyan Oceanfloor. The youngest and undeformed unit, which recordsthe neotectonic regime in the Ankara region, consists ofuplifted and dissected terrace conglomerates ofPlio–Quaternary age, and weakly consolidated to looseconglomeratic sandstones to fine-grained alluvialsediments of Quaternary age.

The Ankara section of the ‹AESZ is geologically verycomplicated (Figure 1). This is because (a) remnants ofthe Sakarya Continent, K›rflehir block, the Menderes-Tauride platform and the intervening sutures (‹zmir-Ankara-Erzincan and the ‹nner Tauride sutures) arejuxtaposed tectonically (Figure 1B), and (b), except forthe Plio–Quaternary neotectonic unit, all the above-mentioned rock assemblages (metamorphosedHercynides, unmetamorphosed Alpides and their volcanicand molassic cover), ranging in age from pre-Triassic toEarly Pliocene, have been superimposed, and eventectonically stacked up by two groups of contractionalstructures, namely the Ankara foreland fold-imbricatethrust to reverse fault zone (AF‹TFZ) and the Ankaraforced fold zone (AFFZ) as a result of both thesubduction-to collisional- and long term post-collisonalevents (Figure 1B). The AFFZ controls the north-northwestern half of the ‹AESZ and is composed mainlyof a number of NE–SW-trending and southeast-vergingmonoclinal to overturned folds and high-angle thrustfaults (reverse faults) such as the Çay›rhan-Beypazar› andthe Ayafl-Pazar monoclinal to overturned folds and theNall›han thrust fault (Koçyi¤it 1991b; Demirci 2000)(Figure 1B). The AF‹TFZ shapes the south-southeasternhalf of the ‹AESZ, and consists of a series of NNE–SSW-trending and SSE-vergent imbricate thrust faults, such asthe Haydarköy, Gelbulas›n, Hanc›l›, Elmada¤, andBedesten thrust faults, along which both the Hercynides(Lalahan Nappe) and the Alpides (the Karakaya andAnatolian nappes) are emplaced onto the UpperMiocene–Lower Pliocene fluvio-lacustrine sedimentaryand volcano-sedimentary sequences (Koçyi¤it 1992;Koçyi¤it et al. 1995). One of the type localities, where thestructures recording the last phase of the palaeotectonicperiod and related contractional features are well-preserved, is the Edige (Elmada¤) area, located ~48 kmeast-southeast of city of Ankara (Figure 1B). One of themain aims of the present paper is to discuss and presentstructural analysis of contractional features representing

the last phase of the contractional palaeotectonic periodrecorded within the rocks and their tectonic contacts inthe Edige area (Figure 1B).

Stratigraphy of the Edige Area

Based on both the age and style of deformation, the rocksin the Edige area are subdivided into two categories: (1)pre-Late Pliocene allochthonous to para-autochthonousrock assemblages that represent the palaeotectonicperiod, and (2) Plio–Quaternary autochthonous rocks(Edigekoru formation) and sediments representing theneotectonic period which are nearly flat-lying and overliewith angular unconformity the erosional surface of theintensely deformed and tectonically transportedpaleotectonic rock assemblages. Based on theiroccurrence ages, palaeotectonic units exposed in theEdige area are, from oldest to youngest, the KarakayaNappe, the Eskiköy nappe, the Anatolian Nappe and thepara-autochthonous Edige formation. They will bedescribed in more detail below.

Palaeotectonic Rocks

Karakaya Nappe

Discontinuous outcrops of a widespread Triassic rockassemblage are best exposed in an approximately E–W-trending belt running from the Biga Peninsula in thewest-southwest and extending throughout the southernpart of Black Sea region in northern Turkey as far asArtvin in the east-northeast (Figure 1C). In this belt, thepre-Triassic Hercynian, Late Triassic Karakaya and theLate Cretaceous Alpine orogenies, and their structures aresuperimposed on each other in a thick imbricate stack;therefore the geology of this belt is very complicated.This rock assemblage was first recognized and named byBingöl et al. (1973) as the so-called ‘Karakaya Formation’in the Biga Peninsula, comprising the western part of thebelt. fiengör & Y›lmaz (1981) and Tüysüz & Yi¤itbafl(1994) had previously interpreted the same rockassemblage to be a marginal basin succession of thesoutherly subducting Palaeo-Tethys. This rockassemblage, together with its basement composed ofpolyphase low-grade metamorphics, was termed theUpper Permian–Triassic ‘Karakaya Complex’ by Okay(1984), who also incorporated the ‘Karakaya Complex’within the the ‘Sakarya Zone’. Koçyi¤it (1987, 1991c)


437

extended the belt of Triassic rock assemblage eastwardsto the Artvin area and named it the Karakaya orogen(Figure 1C).

In the western part of the Karakaya Orogen (BigaPeninsula and Bursa-Bilecik areas), Triassic rocks arepara-autochthonous, and were therefore named theKarakaya group, composed of three subunits (Koçyi¤it etal. 1991b). These are from bottom to top, arkosic clasticrocks approximately 1 km thick (Kendirli Formation), analternation of spilitic pillow basalt flows, pyroclastic rocksand shallow-water carbonates (Bahçecik Formation), anda sedimentary mélange of wildflysch type (OlukmanFormation). The latter is a chaotic mixture of variousblocks of differing origin, age, texture, structure andfacies set in an intensely sheared litharenitic to peliticmatrix. It also contains diverse-sized low-grademetamorphic blocks derived from its basement (LalahanNappe in the Ankara region). The age of carbonate blocksin the matrix of the Karakaya Group ranges fromCarboniferous to Norian (Okan 1982; Koçyi¤it 1987;Koçyi¤it et al. 1991a; Alt›ner & Koçyi¤it 1993; Okay &Mostler 1994; Alt›ner et al. 2000).

In the Biga Peninsula and the Bursa-Bilecik areas, theKarakaya group rests unconformably on the erosionalsurface of the pre-Triassic and polyphase metamorphicrocks, and it is overlain with angular unconformity by awell-defined basal conglomerate, a few metres to ≥1 kmthick, which is the lowest unit of the UpperHettangian–Lower Campanian Ankara Group (Koçyi¤it1987, 1991a; Koçyi¤it et al. 1991a, b; Alt›ner et al.1991; Koçyi¤it & Alt›ner 2002). Exceptionally, in theHal›lar area of the Biga Peninsula, the Karakaya Groupgrades upward into the Jurassic unit indicating thepresence of a remnant Karakaya basin and thediachronous nature of the Karakaya Orogeny (Koçyi¤it &Alt›ner 1990; Alt›ner & Koçyi¤it 1992). In contrast to thesituation in the western Karakaya Orogen, in the Ankararegion one of the sub-units (Kendirli Formation) of theKarakaya group is missing, and the remaining two sub-units (Bahçeli and Olukman formations) togethercomprise an undifferentiated chaotic allochthonoustectono-sedimentary mixture. Therefore, this chaoticmixture of Triassic age was renamed the Karakaya Nappein the Ankara region (Koçyi¤it 1987, 1991c). TheKarakaya Nappe displays widespread but discontinuousoutcrops in an approximately NE–SW-trending belt, and

is thrust from NW to SE on to various tectono-stratigraphic rock units, such as the Anatolian Nappe, theEskiköy nappe and the Edige formation, ranging in agefrom Early Cretaceous to Early Pliocene (Figure 3). Allthese allochthonous and para-autochthonous units andtheir normal stratigraphic or faulted contacts are overlainwith angular unconformity by the Plio-QuaternaryEdigekoru formation (Figures 2 & 3). Therefore theemplacement age of the Karakaya Nappe into its presentposition is bracketed between Early Pliocene at bottomand Late Pliocene at the top.

Eskiköy Nappe

This unit, previously named the ‘Edige ultramafic body’(Say›n 1985), was renamed the Eskiköy nappe due to itsallochthonous nature, as it has been transported tens ofkilometres from its place of origin to its present position.The Eskiköy nappe is another widespread allochthonousunit exposed and mapped at a scale of 1/25.000 in theEdige area (Figure 3). It occurs in more than onesoutheastward facing tectonic slice within a NE–SW-trending belt 0.6–2.6 km wide, 10 km long, located inthe Karacahasan, Edige and Hisarköy areas (Figures 3 &4). The Eskiköy nappe originally represents a deeper andlayered structure of the northern Neotethyan ocean floorand consists of both ultramafic (harzburgite, dunite,pyroxenite and chromatite) and mafic rocks(serpentinized dunite, pyroxenite and massive to layeredgabbro occurred in podiforms). Both these rockassemblages are also accompanied by closely-spaced andirregular magnesite and jel-silica veins (up to 20 cm inthickness), and in places cut across by 1–20-m-long,0.2–15-m-thick and NE–SW-trending doleritic to dioritedykes (Figure 5). Both the top and the bottom tectoniccontacts of the Eskiköy nappe are represented bynorthwesterly dipping imbricate reverse faults with theTriassic Karakaya Nappe, the Cenomanian–LowerCampanian Anatolian Nappe and the UpperMiocene–Lower Pliocene (Turolian) Edige formation(Figures 2 & 3). The emplacement age of the Eskiköynappe into its present-day position is a time slice betweenEarly Pliocene and Late Pliocene, based on its contactrelationship (Sivritepe and Edige imbricate reverse faults)with the youngest palaeotectonic unit, the UpperMiocene–Lower Pliocene Edige formation (Figures 2 &3).


438


439

� � � � � � � � � � � � � � � � ��

��

!��

"��#

��

$%&#

��''��

(��

&��))�

*+,-&�#

*&$%%&#

��

��#

)��,

��

��))�

*&.%%&#

&$%&#

&/%&#

��

&&&�

��

��'

'��0 &&�

�))�

&1%&#

&-&#

!��&&&&&&&&&"�

�#��

��

�&2��&��

��

��&�&�� & ��

��3

&4%&#

&.%&#

&1%&#

%,-&�&+

,-&�#

�� &��#

)��

��!&�)��&#��

��

�

�

5

!

"

��'��!6&7�� &��'��!��!6&)�� 8��9��&��#��

��

��'�!�#�� &��&#�:��&�8&9��'&5��'7��&��&��'�� &'��!&��&��&)��&#��:

��

��!&�)��&#��

��!&��#�8��&��'&2��;5��6&!��6&) ��:��3��&5 &#��'��&9��'

��&��5��&#�8��&��'&2'��)��;�!&!��6) ��:��&��!&��55��3

)��&5��7�6&)��'6&�� &��!2'��8��!&��!&��;�!3&'��)��

8��&5��

8��&��&��!&��&'��'��

!<&��'��!6&)�� 6&)�� &5�!!�!&��!&��#��<&5��7��5��7��&��'��&'��#��'��'��&��5<&��!&'��!'��'��'��#�!'��&��&7��&&&&��'��!��&��&��#��&��<&��'��!6&)�� &5�'��&��#��

�� !�� !��

"�� #�� "�� $��

%�� !�� $��!�� &��!��'��

(�� !��$�� )�� '��

$�� *�+��*�� ,�� '�� -��!�� !��

&�� .�� '��/�� 0��

� ��(��!�� 1��

/�2��!��/�2��/�2��,��!�!��!��

��

��

�3��

��

& ��

��,

��

�

��, ��

2��&��&'��3��&��))�

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


440

�,�0��

#��

�*�/� �/.

?�+��@)

�.

�,�A

��+%�(�)�*B

"=22

��)�%)

*B

""41

C�D��+@8$�E��%

��?��

�� #��

�*�/�

�/.

��*B

"""=

"<75

��)�)-+

�@>@)��!�

,�+��%��%

@�

$�)�*B

F #�� #

��

*�/� �/.

��*��

��:�

�.

�,�A

� #��

*�/�

�

/.

*@+@)

�*B

"=37

��)�&%�*

B

"9=4

��.��

� #��

�*�/�

�/.

"��

�

�

�

�

1<

9<

9=94

=2

94

9597

=1

=="4

=7

9=9=92

93

=<

=2

9<91

94

7=9<

=41<

7=

=="2

"4

"1

"=

"2

1<

1<

7<

91

=7

=42

922

"4

92

92

=4

94

7<

4<71

=2

=29<

5<

741= "2<

"3<

91

"1

=<

5<

92<

71<

42<

4<

2<72

1=

�,�0�

9=

"

5<

74

7

.

��!�)��*B

�. �,�A�� /.

��

��

��

��!�)��

��!��(��+

��)�+��::�

��(��(�(��(�

��(��(�(��(�

��)�)-+��::�

��::�

��(��(�(��(�

��!��

��

��)��:��$��!

��)�

��(��C��

�+�(��C��

�'��

�$��G��:��

��)��:��H

��'��:�(��

:��

��'��'�(��(�

�#

�,��!��!�(��(��(��

��H'��:�:��H��

��

Figu

re 3

. G

eolo

gica

l map

of

the

Edig

e ar

ea.

Anatolian Nappe

This tectonic unit was previously named the ‘AnatolianComplex’ by Koçyi¤it (1991a). However, it was renamedthe Anatolian Nappe by Koçyi¤it et al. (1995) as it hadbeen tectonically transported a long distance. In general,the Anatolian Nappe is an undifferentiated colouredophiolitic mélange or subduction complex accreted at thesouth-facing northern active margin of the northerlysubducting northern Neo-Tethyan ocean floor (fiengör &Y›lmaz 1981; Koçyi¤it 1991a; Koçyi¤it et al. 2003).

In general, the Anatolian Nappe is a chaotic tectono-sedimentary mixture of various blocks of dissimilar age,origin, facies and size set in a pervasively sheared, semi-schistose and/or mylonitized fine-grained matrixcomposed of sandstone, which contains mostly detritalophiolitic material, shale, turbidite and pelagic mudstone.Blocks in it range from a few centimetres to tens ofkilometres in size. They are generally lensoidal andirregular in shape, and rootless. Secondarymineralization, such as calcitization and silicification, ismost common on polished and striated block surfaces.Based on their origins, blocks fall into four majorcategories: (1) passive continental margin-derived blocks,which are dominated by carbonate blocks of dissimilarage and facies (blocks of the Ankara Group of Koçyi¤it1991a); (2) active continental margin-derived blocks,which are mostly volcanic to ophiolitic material-richolistostromes, turbidites and broken formations (Figure6); (3) ocean floor-derived blocks, mostly ultramafic tomafic rocks and their sedimentary cover comprising theoceanic lithosphere such as harzburgite, pyroxenite,dunite, serpentinized dunite, gabbro, chromitite, pillowedbasalt, diabase, manganese-bearing radiolarian chert,tuff-tuffite, other pyroclastic rocks, radiolarite,radiolarian-rich wackestone, pelagic cherty limestoneinterbedded with red radiolarian chert bands and volcanicbreccias (Figures 4 & 6), and (4) older basement-derivedblocks, such as marble, recrystallized limestone,greywacke, fossiliferous limestone blocks ofCarboniferous, Permian and Triassic ages, and low-grademetamorphics such as green schist and metabasic rocksof the Lalahan Nappe. The active margin- and ocean floor-derived blocks display mostly a more regular tectono-stratigraphical sequence within a thick tectonic slice orimbricate stack bounded by imbricate thrusts to reversefaults (Figures 3, 4 & 6). One of the type localities wherethe Anatolian Nappe, its various lithological components

and their internal structures are well-exposed is theK›z›lda¤ (Hisarköy-Elmada¤) area (Figure 4 & 6).

Imbricates or tectonic slices are mostly in fault contactwith each other. Some of these imbricate reverse fault-bounded slices of dissimilar age, lithofacies and originoccur in fault-parallel strips of contrasting colours, whichcommonly correspond to the internal smaller imbricatestructures characterizing the Anatolian Nappe. Pinch- andswells, bedding pull-aparts, dispersed phacoids ofsandstones and limestones, disrupted beds, hinges andfolds (closed, upright, overturned, recumbent, isoclinaland disharmonic folds), quartz- and/or calcite-filled shearplanes, spaced to axial-plane cleavages, local thrust toreverse and normal faults and discrete thrust nappes arecommon mesoscopic-scale features observed within thetrench fill turbidites, Rotalipora-bearing mudstone ofCenomanian age, radiolarian-rich wackestone, radiolariancherts and the volcaniclastic sedimentary pile. All thesefeatures seem to have resulted from a single progressivedeformation changing from an early stage ductile flow toadvanced stage brittle failure, due to simple shearingwhich prevailed at the base of the inner trench slopeduring rapid subduction of a relatively thin trench floorsequence (Moore & Wheeler 1978; Moore 1979; Moore& Karig 1980; Nelson 1982).

The apparent thickness of the Anatolian Nappe in thestudy area is about ≥ 1 km, and the youngest blockidentified within its clastic matrix is a thin bedded, pinkishto red pelagic biomicrite of Santonian–Early Campanianage (Koçyi¤it 1991a). Further north, outside the studyarea, the Anatolian Complex comprising the AnatolianNappe, is overlain depositionally by Middle Campanianolistostromal levels of the K›z›lkaya Formation, at thebase of a well-preserved and defined accretionaryperipheral fore-arc sequence (Koçyi¤it 1991a). Thus, theyoungest growth age of the Anatolian Complex as anaccretionary prism at the base of south-facing inner slopeof the northern Neotethyan oceanic trench is MiddleCampanian. However, the emplacement age of theAnatolian Complex as the Anatolian Nappe into its presentposition is a time slice between Early Pliocene and LatePliocene (Figures 2 & 3).

Unfortunately, all these allochthonous units (TheLalahan Nappe, the Karakaya Nappe, the Eskiköy nappeand the Anatolian Nappe), described briefly in previoussections were formerly and erroneously combined into asingle tectonic unit named the so-called ‘Ankara Mélange’


441


442

��%%%

+++

�#�#�#

�=��(>�

�=��(>�

�=��(>�

141414

-1-1-1

/-/-/-$/$/$/

4/4/4/

?-?-?-

-%-%-%

/4/4/4

,�=��(>�

,�=��(>�

,�=��(>�

(��

&"��

(��

&"��

(��

&"��

(��)�&'

��,(��

��)�&'��,

(��)�&'

��,

(��5�@A&�,

(��5�@A&�,

(��5�@A&�,

B��5��&�,

B��5��&�,

B��5��&�,/%/%/%

(A�AC��&�,

(A�AC��&�,

(A�AC��&�,

"""

��A�@��

��A�@��

��A�@��

1%1%1%

�� !"#

�� !"#

�� !"#

��$%

��$%

��$%

��DDD��

��EEEBBB��

��

��

"""��

BBB��(((��

��(((

��EEEBBB��

��

��

��

"""��

��

(((��FFF��DDD

�� EEEBBB��

��

��

��"""��

��

+++111

$$$///

-�-�-�-5-5-5

-�-�-�-!-!-!

-�-�-��

��

��

???...

444GGG

+%+%+%++++++

+1+1+1+$+$+$

Figu

re 4

. G

eolo

gica

l m

ap o

f th

e K

›z›ld

a¤ (

His

arkö

y-Ed

ige)

are

a. 1

– Tu

rolia

n Ed

ige

form

atio

n, 2

– Te

cton

ic c

onta

ct (

TC),

3–

Low

er c

reta

ceou

s Es

kikö

y na

ppe,

4–

Dol

erite

-dio

rite

dik

e, 5

a– u

ndiff

eren

tiate

d co

lour

ed o

phio

litic

mél

ange

(m

ostly

mat

rix

of b

lock

s co

mpr

isin

g th

e An

atol

ian

Nap

pe),

5b–

pill

owed

bas

alt,

5c–

bedd

ed-m

assi

ve r

adio

lari

te t

o pe

lagi

c lim

esto

ne a

ltern

atio

n, 5

d– U

pper

Cre

tace

ous

a fly

scho

idal

se

quen

ce,

5e–

Perm

ian–

Jura

ssic

Lim

esto

ne b

lock

s 6–

Plio

–Qua

tern

ary

fluvi

al c

last

ics

(Edi

geko

ru f

orm

atio

n),

7– Q

uate

rnar

y al

luvi

al s

edim

ents

, 8–

str

ike

and

dip

of b

eddi

ng,

9– t

hrus

t to

rev

erse

fau

lts,

10–

stri

ke-s

lip f

ault

with

nor

mal

com

pone

nt, 1

1– O

bliq

ue-s

lip n

orm

al f

ault

with

str

ike-

slip

com

pone

nt, 1

2– li

ne o

f m

easu

red

sect

ion,

and

13–

line

of

geol

ogic

alcr

oss-

sec

tions

.

by Bailey & McCallian (1953). Instead, regionalunconformities, rift and passive to active marginsequences separating them at well-preserved outcropsshowing normal stratigraphical relationships indicate thatthey are separately mappable products of differentorogenies (the Hercynian, the Karakaya and the Alpineorogenies, respectively) in the ‹AESZ (Koçyi¤it 1987,1991a, c; Koçyi¤it et al. 1991a; Alt›ner & Koçyi¤it 1993;Alt›ner et al. 2000; Koçyi¤it & Alt›ner 2002).

Edige Formation

The type locality of this formation is Edige and adjacentareas, where it is well-exposed and displays well-beddedinternal structure. The Edige formation crops out withinseveral 0.2–3 km wide and approximately NE–SW-trending belts around Karacahasan and Edige villages. It

has an erosional stratigraphical bottom contact with boththe Eskiköy and Anatolian nappes, but a faulted topcontact with the same units (Figure 3). The Edigeformation, from bottom to top, consists of four majorlithofacies: (a) basal conglomerate, (b) fluvial sandstone-mudstone alternation, (c) lacustrine shale-marl andlimestone alternation, and (d) unsorted conglomerate(Figure 3). The basal conglomerate is green-yellow-redand variegated in colour, and polygenetic to unsorted innature. It consists of well-rounded pebbles, cobbles andboulders derived from allochthonous rock assemblagesmentioned above. Clasts up to 30 cm in diameter aremostly radiolarite, marble, recrystallized limestone,greywacke, spilitic basalt, gabbro, serpentinite, turbiditicsandstone, chert, cherty limestone, dunite and andesiteclasts. The conglomerates are debris-flow to braided riverdeposits with an iron-rich matrix and calcite cement. They


443

Figure 5. Close-up view of a doleritic dyke cutting across calcitized and silicified serpentinite (~150 m NW of Edige village).

are a few meters to 20 m thick, and overlie the olderrocks with angular unconformity. They grade upwardinto the red conglomeratic sandstone, sandstone,

siltstone and mudstone alternation with the intercalationof various sized and lensoidal channel conglomerates orscour-and-fill structures, which indicate a flood plaindepositional setting. This 130-m-thick flood plain depositdisplays a lateral facies change into a lacustrine blue-green-white and light brown shale-marl and limestonealternation up to 70 m in thickness. Both the flood plainand the lacustrine deposits are overlain conformably by aweakly lithified to loose red conglomerate ranging from afew metres to 50 m in thickness (Figure 3).

The Edige formation contains rich mammalian fossilsin places, particularly along the transitional zone betweenits flood plain and lacustrine facies. One of these fossillocalities and its rich fossil assemblage, plotted and listedon the tectono-stratigraphical column (F in Figure 3), waspreviously detected and identified by Saraç (1994). Basedon this fossil assemblage, the key horizon labelled byletter F, that indicates the fossil location within the Edigeformation, is Early Turolian (MN 11) (Upper Tortonian)in age. However, the sequence including the fossillocation continues upwards for about 100 m in thickness,therefore, the remaining upper part of the sequence maycontinue up to uppermost Turolian (Early Pliocene) inage. Thus, the age of whole continental sequence wasaccepted to be Turolian (Upper Tortonian–Early Pliocene)in the present paper.

Neotectonic Rocks

These rocks and sediments accumulated during theneotectonic regime in the Ankara region. Neotectonicunits are characterized by mostly uplifted and dissectedriver to fault terrace conglomerates of Plio–Quaternaryage suspended at different elevations along the margin-boundary faults, and the depocentral Quaternarysediments accumulated inside the active basins (Koçyi¤it1991b). One of the neotectonic units is well-exposed atlimited and isolated outcrops in the Edige area, where itis named as the Edigekoru formation (Figures 2 & 3).This unit is described below.

Edigekoru Formation

This fluvial terrace conglomerate is exposed at threeoutcrops north and south of Edige village (Figures 3 & 4).The type locality of the formation is the Edigekorudistrict, where the internal structure and its basal contact


444

.�*�.�0� , � � � � � � � �

'�()��

I�J

=2

54

"<<

91

"92

=3

4"<432"7

"4

=7

"1

7<

97

=1

=<

��!��(��

$��

:��H��$��

�:��(��(��(�$��((��

:��H��$��

:��H��$��

��K��(��H��'��!��$��!��(��:��(��:��(��

��

��!��(��(��$��

��

�:��(��

��:��

�:��(��I�7��J��:��I�9��J(��(��I=��J

��:��

��!�$$��

�

�

�

I�L��(��(�(��(�J

�

Figure 6. K›z›lda¤ measured tectono-stratigraphical measured sectionof the lithologies comprising a tectonic slice within theAnatolian Nappe.

with the youngest palaeotectonic unit, the UpperMiocene–Lower Pliocene Edige formation, are well-exposed (Figure 7). At this locality, in a road cut, theEdigekoru formation overlies with angular unconformitythe steeply dipping and folded Edige formation. A 20–50-

cm-thick, unsorted and weakly consolidated polygeneticbasal conglomerate rests on the erosional surface of theEdige formation, and is overlain by an alternation ofhorizontal beds of conglomeratic sandstone, siltstone,mudstone with the intercalation of lensoidal channelconglomerates (Figure 7). The top of the unit is a freeerosional surface, represented by loose boulder-blockconglomerate. The lower coarse-grained horizonsinterfinger with the fine-grained lacustrine shale andmarls, in places (Saraç 1994). At the type locality, thethickness of the formation is 2 m, but it ranges up to 30m maximum at other localities.

In the Edige area, no fossils were found within theformation, but it is also exposed at a number of outcropselsewhere within the ‹AESZ. It is especially well-preservedin the Sar›larbey (Kazan-Ankara) area, outside thepresent study area, where a mammalian fossil from theArvicolinae family and Rodentia Class was identified

within horizontal lacustrine beds, and a Plio–Pleistoceneage (MN 14-17) was assigned to them by Saraç (2003).The fine-grained horizontal beds of the Edigekoruformation can be correlated with those of Saraç (2003),and may also be Plio–Quaternary in age. The age of theEdigekoru formation has a critical significance in Ankararegion, because, it is undeformed (nearly flat-lying) andseals all the intensely deformed palaeotectonic units andtheir tectonic contacts, i.e. it is a key for the end of thecontractional palaeotectonic period (Ankara OrogenicPhase) and the initiation of the strike-slip neotectonicperiod in Ankara region.

Geological Structures in the Edige Area

Based on their ages and styles, the geological structuresexposed in the Edige area and its neighborhood areclassified into two major categories: (a) palaeotectonicstructures such as the normal faults, folds and imbricatereverse faults, and (b) neotectonic structures such asstrike-slip faults. They will be analysed and describedseparately below.

Palaeotectonic Structures

Normal Faults

These structures occur in two patterns: (1) the mappableand isolated margin-boundary faults between theTurolian Edige formation and older rocks, and (2)mesoscopic fault arrays within the Edige formation.Particularly the Sivritepe imbricate reverse fault was anoriginally SSE-dipping oblique-slip normal fault (margin-boundary fault), which controlled sedimentation of theEdige formation during the Turolian. The Sivritepeimbricate reverse fault is well-exposed on the SSE side ofSivritepe, approximately 1 km northwest of Edige village(Figure 8), and it exposes well-preserved superimposedslickensides indicating three phases of deformation, firstlySE-dipping oblique-slip normal faulting, secondly NNW-dipping reverse faulting, and finally NE–SW-trendingsinistral strike-slip faulting. This is precisely proved by thewell-preserved slickensides (Figure 9a). Kinematicanalysis of the slip-plane data measured on theslickensides at Station 1 (Figure 3) reveals the first phaseof deformation to be an oblique-slip normal faulting withWNW–ESE extension (Figure 9b) during thesedimentation of the Turolian Edige formation. This first


445

��

Figure 7. Close-up view of the angular unconformity (AU) betweenthe overlying nearly flat-lying Plio–Quaternary Edigekoruformation and the steeply dipping Turolian (UpperTortonian–Lower Pliocene) Edige formation (~1.2 kmWNW of Edige village).

phase of extension is also strongly evidenced by the verywidespread normal fault arrays recorded and preservedwithin the Edige formation (Figure 9c). Kinematicanalyses of slip-plane data measured on slickensides atStations 2 and 3 (Figure 3) reveals again the same phaseof deformation by the oblique-slip normal faulting andNW–SE extension (Figure 9d & e).

Folds

The Turolian Edige formation is the youngest unit of thepalaeotectonic period. It displays well-developedmoderately (20–40°) and steeply (40–80°) dippingbedding planes (Figure 10). In general, tilting increasesnear the faulted contacts but decreases by up to 15° awayfrom them (Figure 3). The Edige formation has beendeformed into a series of anticlines and synclines, well-exposed near Edige and Karacahasan villages (Figure 3).Stereographic plots of poles to bedding planes clearlyindicate that the Edige formation experienced a phase ofNW–SE compression (Figure 11), and was folded at atime bracketed by both the Early Pliocene and Late

Pliocene times following its sedimentation. This firstphase of contractional deformation is also evidenced by aseries of SSE-verging imbricate reverse faults (Figure 3).

Imbricate Reverse Faults

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-verging and NE–SW-trending imbricate reverse faults.Some of them, from northwest to southeast, are theElmada¤, Tümbek, Sivritepe, Edige, Kaletepe, K›z›lda¤,Hac›o¤lu and the Bak›rl›k imbricate reverse faults, alongwhich various nappes of dissimilar origin, age andcomposition are emplaced on each other, and also on theyoungest palaeotectonic unit, the Turolian Edigeformation (Figures 3, 4 & 12). The records and analysesof the imbricate reverse faults which redeformed theEdige formation will be documented separately below.

Elmada¤ Imbricate Reverse Fault. At a regional scale,it is an about 150-km-long, ESE-verging and NNE–SSW-


446

��

��

�� !

�� "��#��$%�

Figure 8. Field photograph showing general view of the Sivritepe imbricate reverse fault (view to NE, 1.2 km NW of Edige village).

trending contractional structure located between Çank›r›in the northeast and Elmada¤ in the southwest (Figure1B). It displays a curved to curvilinear trace pattern anddips at an angle of 25° to 80° to the WNW. Only the 10-km-long and NE–SW-trending limited part of theElmada¤ imbricate reverse fault is included in the studyarea (Figure 3). The Triassic Karakaya Nappe has beenthrust southeastwards over the Lower CretaceousEskiköy nappe, the Cenomanian–Lower CampanianAnatolian Nappe and the Turolian Edige formation alongthe Elmada¤ imbricate reverse fault (Figures 3, 12a &13). The youngest rocks disturbed by the reverse faultingare Turolian (Late Miocene–Early Pliocene) in age. In

addition, The Elmada¤ imbricate reverse fault is overlainwith angular unconformity by the Plio–Quaternaryneotectonic rocks and sediments outside the study area.Therefore, its age must be between the Early Plioceneand Late Pliocene.

Sivritepe Imbricate Reverse Fault. This approximately10-km-long, NE–SW-trending and NW-dipping imbricatereverse fault has a curved to curvilinear trace pattern.The Sivritepe imbricate reverse fault extends fromSivritepe in the northeast to Karacakaya village in thesouthwest and displays a fault plane with well-preservedand exposed slickensides in places (Figure 8). Aspreviously explained the Sivritepe imbricate reverse fault


447

��

��

��

��"

��= ��9

��

��

Figure 9. (a) Field photograph showing close-up view of the slickensides with slip-lines indicating oblique-slip normal faulting; (b) stereographicplots 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 (atstation 2 in Figure 3); (d, e) stereographic plots of slip-plane data on the Schmidt lower hemisphere net (data were measured onslickenside of fault arrays within the red beds of the Turolian Edige formation at stations 2 and 3, respectively: Large arrows showlocalized extension direction).

was an originally oblique-slip SE-dipping normal fault.However, it was reactivated as a reverse fault dipping at70–85° to the northwest after both the sedimentationand folding of the Turolian Edige formation. Ultramaficand mafic rocks of the Lower Cretaceous Eskiköy nappeare thrust southeastwards onto the Turolian Edigeformation (Figures 8 & 12): the amount of tectonictransportation of the Eskiköy nappe on the Edigeformation is about 0.3-0.8 km, based on the offset alongthe tear faults (TF in Figure 3). In the north of theEdigekoru district, the Eskiköy nappe, the Edigeformation, and the Sivritepe imbricate reverse faultsuperposing them, are all also overlain with angularunconformity by the Plio–Quaternary Edigekoruformation (Figure 3). Therefore, the timing of thereverse faulting must be between the Early and LatePliocene.

Kaletepe Imbricate Reverse Fault. This approximately16-km-long, NNE–SSW-trending and WNW steeply(50–80°) dipping high-angle thrust fault with a curved-curvilinear trace extends from Kayadibi village (outsidethe study area) in the northeast to Kaletepe in thesouthwest. Only 6 km of its length is included in the studyarea (Figure 3). Various undifferentiated lithologiescomprising the Anatolian Nappe are thrustsoutheastwards on to the red beds of the Edigeformation, i.e., the red beds dip at 35° northwestbeneath the Anatolian Nappe (Figures 12b & 14).

Strike-Slip Faults. Not one isolated strike-slip faultinherited from the palaeotectonic period could be mappedin the study area. However, a very widespreadslickenside, indicating a sinistral strike-slip motion with aconsiderable thrust component, is well-exposed at Station1 (Figure 3). The strike-slip faulting-induced slickensides


448

Figure 10. Field photograph showing general view of moderately dipping red beds comprising the Edige formation (station 4 in Figure 3).

occur in a superimposed pattern on both the first phaseof oblique-slip normal faulting- and oblique-slip reversefaulting-induced slickensides on the plane of the Sivritepeimbricate reverse fault (Figures 15a–c). Kinematicanalyses of slip-plane data obtained from slickensides atstation 1 precisely revealed a sinistral-strike-slip faultingand a horizontal compression operated in NW–SEdirection (Figure 15d). This first phase of contractionaccompanied by the sinistral strike-slip faulting is alsostrongly evidenced by folding, reverse faulting and minorsinistral shear zone dominated by the C-S structures(Figures 11 & 15e).

Consequently, tight to overturned folds withapproximately NE–SW-trending axes, a series of WNW-dipping imbricate reverse faults and sinistral-strike-slipfaulting, that accompanied oblique-slip thrust to reversefaulting, strongly reveal a NW–SE phase of contraction inthe Edige area (the Ankara orogenic phase) (Figures 11 &15d), which appeared after the first phase of extension(Figure 15f). Finally, this last contractional phase of thepalaeotectonic regime was replaced by a strike-slipneotectonic regime in the Late Pliocene.

Neotectonic Structures

Two major groups of structures characterizing theneotectonic period in the present study area are: (1)reactivated older faults, and (2) younger faults. The firstgroup of structures, inherited from the palaeotectonicperiod, still retain their earlier nature as dextral strike-slip faults. Older faults occur on both sides of the K›l›çlarriver valley around Eski Hisar village and are representedby a series of randomly distributed short (0.5–1 km) andWNW–ESE-trending fault segments (Figure 4). Olderfaults cut various lithological components of both theEskiköy and Anatolian nappes and juxtapose them intofault contacts.

The second group of structures, represented byyounger faults formed during the Plio–Quaternaryneotectonic period, are in three categories: (a) NW–SE-trending dextral strike-slip faults, (b) NE–SW-trendingsinistral strike-slip faults, and (c) NNE–SSW toNNW–SSE-trending oblique-slip normal faults with aconsiderable amount of strike-slip components based onthe local distribution pattern of the stress system, inwhich the principal stress axis (σ1) is horizontal and


449

I71��MJ

I2<��J

Figure 11. Stereographic plots of poles to bedding planes on the Schmidt lower hemispherenet (large arrows indicate localized compression prevailed during the deformationof the Edige formation).


450

�E��D&�E

B��

��

�H�

&"��

I

=H�=�

&�EB��

��

�H�

&"��

��

��&��,

�J#

5��&��

�

B

+1%%

+%%% #

4%%

+%%%

+1%%

�E��D&�E

B��

��

�H�

&"��

=H�=�

&&�EB��

��

�H�

&"��

�=�

&�E

B��

��

�H�

&"��

(��

&�EB��

��

�H�

&"��

#

�

�

2�3

253

"2

3

B�(��

��(

&�EB��

��

�H�

&"��

(��K

��&��H

�

��

D��&�E

B��

��

�H�

&"��

(�F��D

(�F��D&�E

B��

��

�H�

&"��

(��

&"��

�

(��)�&'��,

2�

L3

G%%

.%%

�5

�!

�8

��

�&&��''��&(�� &��))�6&�&&)��!��;5��'��)��6&�&&�� '��;��!&��#

�'��&2M��''�� &��'36

�&&!

��

��55��&

2��'��

36&�&&��!&��!��

&5��6&��&&��

!�88��

��!&

��!&�

)��&#

��

2#�'�� &��#

�� &��#

)��&#��:36&�&&8��9��'��&'�!�#�� &'�N��&2�

��&��

��

�� & ��36

&&7�� &��'��!��!&��&��'�&��#��'��!'��

��&2

�� 36&�&&�

��&��9��&'�!�#��',

�

2�3

2O&��;��

��&��!

&9��

��&'��&��&��

�&'�#�3

Figu

re 1

2.G

eolo

gica

l cro

ss-s

ectio

ns a

long

the

line

s A-

B, C

-D a

nd E

-F (

see

Figu

res

3 &

4 f

or lo

catio

ns o

f se

ctio

ns).


451

Figure 13. Field photograph showing a general view of the Elmada¤ imbricate reverse fault along which the Triassic Karakaya Nappe is emplacedfrom 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 CampanianAnatolian Nappe is emplaced from NW to SE onto the Turolian Edige formation (view to NW).


452

��

"

=

"

=

� ��

� �

��

��

��

� ��

��

Figu

re 1

5.(a

)Fi

eld

phot

ogra

ph s

how

ing

clos

e-up

vie

w o

f sl

icke

nsid

es o

f si

nist

ral s

trik

e-sl

ip f

ault

(Sta

tion

1 in

Fig

ure

3);

(b, c

)fie

ld p

hoto

grap

hs s

how

ing

supe

rim

pose

d sl

icke

nsid

es (

1. o

lder

obliq

ue-s

lip n

orm

al f

aulti

ng,

and

2. y

oung

er s

inis

tral

str

ike-

slip

fau

lting

); (

d)st

ereo

grap

hic

plot

s of

slip

-pla

ne d

ata

on t

he S

chm

idt

low

er h

emis

pher

e ne

t (d

ata

wer

e m

easu

red

onFi

gure

15a

at

stat

ion

1; la

rge

arro

ws

indi

cate

the

loca

lized

com

pres

sion

pre

vaile

d du

ring

def

orm

atio

n of

the

Edi

ge f

orm

atio

n); (

e)fie

ld p

hoto

grap

h sh

owin

g C-

S st

ruct

ure

indi

catin

ga

mes

osco

pic

sini

stra

l she

ar z

one

alon

g th

e Si

vrite

pe im

bric

ate

reve

rse

faul

t at

sta

tion

1 in

Fig

ure

3; (

f)st

ereo

grap

hic

plot

s of

slip

-pla

ne d

ata

on t

he S

chm

idt

low

er h

emis

pher

e ne

t(d

ata

wer

e m

easu

red

on F

igur

e 15

c2 a

t st

atio

n 1;

larg

e ar

row

s in

dica

te a

loca

lized

ext

ensi

on p

reva

iled

duri

ng s

edim

enta

tion

of t

he E

dige

for

mat

ion)

.

operating in approximately N–S direction, and theintermediate axis (σ2) is vertical. This distribution of thestress axes overprinted the Edige formation (Figure 16),and was recently proved once more by the focalmechanism solution of the 2005.07.31, Mw= 5.2 Balaearthquake (HARWARD), sourced from a segment withinNE–SW-trending sinistral strike-slip fault zones such asthe Balaban and the Küreda¤ fault zones. The Balabanfault zone is a 1–6-km-wide, 60-km-long and NE–SW-trending sinistral simple shear zone located betweenTolköy village (11 Km NW of Bala County) in thesouthwest and the Dutlua¤›l plateau (6 km north of IrmakTown) in the northeast (Koçyi¤it & Deveci, inpreparation). The present study area is locatedapproximately 42 km northeast of Bala, and faultsexposed in the study area comprise the northeasternextension of both the Balaban and Küreda¤ fault zones. Ingeneral, neotectonic faults occur in three fault sets atthree localities in the study area. These are the Karagölfault set, the K›l›çlar fault set and the Hisarköy fault set(Figures 4, 17 & 18).

Karagöl Fault Set

On a regional scale, this structure comprises the north-easternmost extension of the 3–9-km-wide, 39-km-longand NE–SW-trending sinistral strike-slip Elmada¤ faultzone (Number 20 in Figure 1), which controls thesoutheastern mountain front of the Elmada¤ highlandsand is located between Beynam Town in the southwestand Elmada¤ County in the northeast. The Karagöl faultset is a 1-9-km-long, 3-km-wide and NE–SW-trendingsinistral strike-slip fault set located between Elmada¤County in the northeast and Yerliyurt hill in the southwest(Figure 17). It consists of closely-spaced, 1–9 km longand parallel fault segments. Fault-controlled drainagesystems such as the Karagöl, Tekke and Otamar streams,Plio–Quaternary depressions bounded by faults, linearfault traces are common morphotectonic expressions ofthe Karagöl fault set. The longest segment of this set isthe Elmada¤ fault, which controls southeastern slope ofthe Karagöl stream valley and passes beneath theoverpass over the Ankara-Elmada¤-K›r›kkale highway(Figure 17).

K›l›çlar Fault Set

This structure comprises the north-easternmostextension of the Balaban fault zone, which controls

development of a very young depression, the ‘Balabanplain’. The K›l›çlar fault set is a 0.1–2-km-wide, 5–15-km-long and NNE–SSW-trending simple shear zonecharacterized by a few oblique-slip normal faults locatedbetween K›l›çlar Town in the south and Dutlua¤›l plateauin the north (Figure 18). The K›l›çlar fault set consists ofclosely-spaced, parallel fault segments 5–15 km long. Thelongest segment, which was dextrally offset by a shortNE–SW-trending dextral strike-slip fault, is the 15-km-long K›l›çlar fault, which displays a steeply sloping andwestward facing fault scarp as a natural response to theoblique-slip normal motion on it. It tectonically juxtaposesthe Upper Cretaceous pillowed basalts with Quaternaryalluvial sediments. Fault-controlled offset drainagesystems such as the K›l›çlar, Kurba¤al› and Kuflçal› rivers,uplifted and dissected Plio–Quaternary terraceconglomerate, tectonic juxtaposition of both Quaternarysediments and pre-Upper Pliocene basement rocks arecommon morphotectonic and geological expressions ofthe K›l›çlar fault set (Figure 18).

Hisarköy Fault Set

This structure is a 1–3-km-wide, 14-km-long and


453

��

Figure 16. Stereographic plots of slip-plane data on the Schmidtlower hemisphere net (data were measured at station 4 inFigure 3; large arrows indicate a localized N–Scompression which has been prevailing since Late Plioceneand governing the strike-slip neotectonic period in theEdige area).

NNE–SSW-trending oblique-slip normal fault set. Itcomprises the Hisarköy-Edige section of the Balaban faultzone and is located between Kuflçuali village in the south(outside of the study area) and Edige in the north. Thenorthern half of the fault set is within the present studyarea, and consists of six parallel to sub-parallel, closely-spaced, various-sized and steeply dipping oblique-slipnormal fault segments with a considerable sinistral strike-slip component (Figure 4). Fault-controlled offsetdrainage systems such as the Kocatepe and Balabanrivers, and tectonic juxtaposition of various lithologicalcomponents of both the Anatolian and Eskiköy nappesand the Turolian Edige formation with each other andwith the Quaternary alluvial sediments are commonmorphotectonic and geological expressions of theHisarköy fault set (Figure 4).

Most fault segments comprising the fault setsdescribed briefly above are also seismically active, as

shown by the local (around Elmada¤ County and theBalaban depression) concentration of small earthquakeswith magnitudes Ml= 1–4 recorded and analyzed byErgin et al. (2003). Thus, it can be concluded that theneotectonic regime in the Ankara section of the ‹AESZ ispredominantly characterized by strike-slip faulting whichcommenced in Late Pliocene time.

Discussion and Conclusion

The intra-continental convergence and the developmenthistory of the ‹AESZ lasted throughout theOligocene–Miocene and Early Pliocene time intervals afterthe Late Eocene final collision and total subduction of theintervening oceanic lithosphere between the SakaryaContinent in the north and the Menderes-Taurideplatform to K›rflehir block in the south in the Ankararegion (Koçyi¤it 1991a; Koçyi¤it et al. 1995, 2003). Asa result of the Late Eocene–Early Pliocene intra-


454

�

+/4-

�� &��

+/-/

��&'��,

% +��#��&'��,

�E��

�D&�

�,

�#�!�@�9��)�''

�#�!�@�88��&!�'��

�E�

��D&"��

(��0�&'��,

�� &'�!�#��'

��9��&8��

��8��#��

��''��&(�� &��))�

'��#''��'��&'��'��)&8��'7��&#��&��#��#)��

�#

��A&��

Figure 17. Geological map of the Karagöl fault set.


455

� &�

'�� (��

)��*�) ��*

��

��

��) &�

��

'��

.��.��N/��

I/��.��J.�� .��.��

��

��

O��!�)��

��'��(��)��:��!

��)��:��

��)��:��!��

��)��:��

(��:��

(��(��

��!��

��)��:��

�'��

��

��

�0/.�

��/��

�C��!��

O��!��

��'��(��!

O��

��

O��:��

��!��

��)��:��!

�'��

��!

��!

$+

��.��,��,

�0/.�

��/��

Tabl

e 1.

Su

mm

ary

of m

ajor

pro

cess

es,

even

ts,

geol

ogic

al s

truc

ture

s, t

ecto

nic

regi

mes

, an

d tr

ansi

tion

from

pal

aeot

ecto

nic

peri

od t

o ne

otec

toni

c pe

riod

in t

he E

dige

are

a.

continental convergence, the Ankara section of the ‹AESZbecame emergent, while at the same time the whole ofthe pre-Upper Pliocene rock assemblages weretectonically stacked up in a broad foreland fold-imbricatethrust to reverse fault zone complex characterized byboth the Ankara forced folds and SSE-verging imbricatethrusts. This long-term convergence also led to crustalshortening, uplift and over-thickening, in which localfailure was evidenced by the intervening short-termphases of extension recorded in the fluvio-lacustrinesedimentary systems.

One type locality where these processes, events,short-term phases of both extension and contraction andrelated structures are well-recorded and preserved is theEdige area (Figure 3 & Table 1). The intra-continentalconvergence, dominated by the contractional tectonicregime, was locally interrupted by a short-term phase ofWNW–ESE extension in the Edige area, recorded by thedeposition of the Turolian Edige formation (Figures 9, 15f & Table 1). Towards the end of the Edige formationsedimentation, the phase of extension was replaced by ashort-term phase of NW–SE contraction (AnkaraOrogenic Phase), which deformed, uplifted andincorporated the Edige formation into the Ankaraforeland fold-imbricate thrust to reverse fault zone byfolding, thrust to reverse faulting and finally strike-slipfaulting during the Early Pliocene and/or a time slicebetween the Early and Late Pliocene (Figures 11, 12,15a–e & Table 1). The long-term and regional intra-continental convergence continued till the neotectonicperiod, dominated by an active strike-slip faulting. Theneotectonic period is evidenced by an angularunconformity, which underlies the undeformed (nearlyflat-lying) Edigekoru formation and seals the entireintensely deformed (tilted, folded, cleaved and faulted)rock assemblages and structures of the Ankara forelandfold-imbricate thrust to reverse fault zone. The activestrike-slip faulting caused by a new phase of compressionis evidenced by both the very young deformationalrecords in the Edige Formation (Figure 16) and the focalmechanism solutions of recent earthquakes (e.g.,2005.07.31, Mw= 5.2 Bala earthquake) sourced fromthe fault segments of the Elmada¤, Balaban and theKüreda¤ fault zones. The strike-slip neotectonic regimehas been extant under the control of the approximatelyN–S principal stress since the Late Pliocene (Figure 16 &Table 1). Thus, it can be concluded that the lastpalaeotectonic period, characterized by a contractionaltectonic regime, was replaced by the strike-slipneotectonic regime, i.e., the neotectonic period, whichwas initiated in the Ankara region in the Late Pliocene.

Acknowledgement

The authors would like to express their sincere thanks toanonymous reviewers whose comments have greatlyimproved an earlier version of the present text. John A.Winchester edited the English of the final text.


456

�%�%>��

��)

��)�+��$�

��)�)�+��$�

��.�6.��

/.

��.�6.�� /.

��,�#�� /.

�%�%>��B

��&>�

�%��B

��$�E��%��B

��:%��B

,��E%��

��(��(�(��!��:��/::��(��$��()�

��)��:��

�$��G��:��H��'��)��:�(��:��

)�

< =

Figure 18. Geological map of the K›l›çlar fault set.


457

ReferencesACH, JA. 1982. The Petrochemistry of the Ankara Volcanics, Central

Turkey. MSc Thesis, State University of New York at Albany, USA.

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. &HAKYEMEZ, Y. 1984. Ankara-Elmada¤-Kalecik dolayının jeolojiözellikleri [Geological characteristics of Ankara-Elmada¤-Kalecikregion]. Jeoloji Mühendisli¤i Dergisi 20, 21–46 [in Turkish withEnglish abstract].

ALTINER, D., KOÇY‹⁄‹T, A., FARANACCI, A., NICOSSIA, U. & CONTI, M.A. 1991.Kuzeybatı Anadolu güneyinin Jura-Erken Kretasede paleoco¤rafikevrimi [Jurassic–Early Cretaceous palaeogeographic evolution ofsouthern part of northwest Anatolia]. Do¤a Türk YerbilimleriDergisi, 1, 1–9.

ALTINER, D. & KOÇY‹⁄‹T, A. 1992. Kuzeybatı Anadolu güneyinin Jura-Erken Kretase’de paleoco¤rafik evrimi [Palaeogeographicevolution of south of NW Anatolia during Jurassic–EarlyCretaceous time]. Do¤a Türk Yerbilimleri Dergisi 1, 1–9 [inTurkish with English abstract].

ALTINER, D. & KOÇY‹⁄‹T, A. 1993. Third remark on the geology ofKarakaya Basin: an Anisian megablock in northern centralAnatolia: Micropaleontologic, stratigraphic and tectonicimplications for the rifting stage of Karakaya basin, Turkey.Revue de Paléogiologie 12, 1–17.

ALTINER, D., ÖZKAN-ALTINER, S. & KOÇY‹⁄‹T, A. 2000. Late Permianforaminiferal biofacies belts in Turkey: palaeogeographic andtectonic implications. In: BOZKURT, E., WINCHESTER, J.A. & PIPER,J.D.A. (eds), Tectonics and Magmatism in Turkey and theSurrounding Area. Geological Society, London, SpecialPublications 173, 83–96.

BAILEY, E.B. & MCCALLIAN, W.C. 1953. The Ankara mélange and theAnatolian thrust. Royal Society of London, PhilosophicalTransactions 62, 403–442.

BATMAN, B. 1978. Geological evolution of northern part of Haymanaregion and study of mélange in the area, I: Stratigraphic units.Hacettepe University Bulletin of Earth Sciences 4, 95–124.

B‹NGÖL, E., AKYÜREK, B. & KORKMAZER, B. 1973. Biga yarımadasınınjeolojisi ve Karakaya formasyonunun bazı özellikleri [Geology ofBiga Peninsula and characteristics of Karakaya formation].Cumhuriyet’in 50. yılı Yerbilimleri Kongresi Tebli¤leri,Proceedings, 70–77 [in Turkish with English abstract].

BOZKURT, E., KOÇY‹⁄‹T, A., WINCHESTER, J.A., HOLLAND, G. & BEYHAN, A.1999. Petrochemistry of the Oyaca-Kedikayası (Ankara) dacites:evidence for the post-collisional tectonic evolution of north-central Anatolia, Turkey. Geological Journal 34, 223–231

DEM‹RC‹, C. 2000. Structural Analysis in Beypazarı-Ayafl-Kazan-PeçenekArea, NW of Ankara (Turkey). PhD Thesis, Middle East TechnicalUniversity, Engineering Faculty, Department of GeologicalEngineering [unpublished].

DOKUZ, A. & TANYOLU, E. 2006. Geochemical constraints on theprovenance, mineral sorting and subaerial weathering of LowerJurassic and Upper Cretaceous clastic rocks of the EasternPontides, Yusufeli (Artvin), NE Turkey. Turkish Journal of EarthSciences 15, 181–209.

ERG‹N, M., ÖZALAYBEY, S., AKTAR, M., B‹ÇMEN, F., TAPIRDAMAZ, C., YÖRÜK,A., TARANCIO⁄LU, A., BELGEN, A., YÜCE, H., ERKAN, B. & YAKAN, H.2003. Kazan-Trona Yata¤ının Depremselli¤i Sonuç Raporu [FinalReport on the Seismicity of Kazan Trona Prospect]. TürkiyeBilimsel ve Teknik Arafltırma Kurumu, Marmara ArafltırmaMerkezi, Gebze-Kocaeli, Project no. 5037101 [in Turkish].

EROL, O. 1951. Ayafl Da¤ları ve Mürted Ovasının Kuzey BölümüHakkında Rapor [A report on the Ayafl Mountains and NorthernPart of Mürted Plain]. General Directorate for Mineral Researchand Exploration Institute (MTA) Report no. 2456 [in Turkish,unpublsihed].

EROL, O. 1954. Ankara ve Civarının Jeolojisi Hakkında Rapor [A Reporton the Geology of Ankara and Its Surrounings]. GeneralDirectorate for Mineral Research and Exploration Institute (MTA),Report no. 2491 [in Turkish, unpublished].

EROL, O. 1955. Köro¤lu-Iflıkda¤ları volkanik kütlesinin orta bölümleri ileBeypazarı-Ayafl arasındaki Neojen havzasının jeolojisi hakkındarapor [A Report on the Central Part of Köro¤lu-Iflıkda¤larıVolcanic Body and Neogene Basin between Beypazarı and Ayafl].General Directorate for Mineral Research and ExplorationInstitute (MTA) Report no. 2279 [in Turkish, unpublished].

EROL L, O. 1980. Türkiye’de Neojen ve Kuvaterner aflınım dönemleri, budönemlerin aflınım yüzeyleri ile yaflıt (korelan) tortullara görebelirlenmesi [Neogene and Quaternary erosional stages in Turkey,and identification of these stages with correlative sediments].Jeomorfoloji Dergisi C8, 1–40 [in Turkish with English abstract].

GÖKTEN, E., KAZANCI, N. & ACAR, fi. 1988. Stratigraphy and tectonics ofLate Cretaceous–Pliocene series in the north-west of Ankarabetween Ba¤lum and Kazan. Mineral Research and ExplorationInstitute of Turkey (MTA) Bulletin 108, 69–81 [in Turkish withEnglish abstract].

GÖKTEN, E., ÖZAKSOY, V. & KARAKUfi, V. 1996. Tertiary volcanics andtectonic evolution of the Ayafl-Güdül-Çeltikçi region. InternationalGeology Review 38, 926–934.

GÖRÜR, N., OKTAY, F., SEYMEN, ‹. & fiENGÖR, A.M.C. 1984. Paleotectonicevolution of the Tuzgölü basin complex: sedimentary record of aNeotethyan closure. In: DIXSON, J.E. & ROBERTSON, A.H.F. (eds),The Geological Evolution of the Eastern Mediterranean.Geological Society, London, Special Publications 17, 467–482.

KAPLAN, T. 2004. Neotectonics and Seismicity of the Ankara Region: ACase Study in the Urufl Area. MSc Thesis, Middle East TechnicalUniversity, Engineering Faculty, Department of GeologicalEngineering [Unpublished].

KAYMAKCI, N. 2000. Tectono-stratigraphical Evolution of the Çankırıbasin (central Anatolia, Turkey). PhD Thesis, GeologicaUltraiectina, No 190, Utrecht University Faculty of Earth Sciences,The Netherland, ISBN 90-5744-047-4.

KAZANCI, N. & GÖKTEN, E. 1988. Lithofacies features and tectonicenvironments of the continental Paleocene volcanoclastics inAnkara region. METU Journal of Pure and Applied Sciences 21,271–282.

KELLER, J., JUNG, D., ECKHARDT, F.J. & KREUZER, H. 1992. Radiometricages and Chemical characterization of Galatean andesite massif,Pontus, Turkey. Acta Vulcanologica 2, 267–276.

KOÇY‹⁄‹T, A. 1987. Hasano¤lan (Ankara) yöresinin tektono-stratigrafisi:Karakaya Orojenik Kufla¤ı’nın evrimi [Tectono-stratigraphy ofHasano¤lan (Ankara) region: evolution of Karakaya OrogenicZone]. Hacettepe Üniversitesi Yerbilimleri Dergisi 14, 269–293.[in Turkish with English abstract].

KOÇY‹⁄‹T, A. 1991a. An example of an accretionary forearc basin fromnorthern Central Anatolia and its implications for the history ofsubduction of Neo-Tethys in Turkey. Geological Society ofAmerica Bulletin 103, 22–36.

KOÇY‹⁄‹T, A. 1991b. Changing stress orientation in progressiveintracontinental deformation as indicated by the Neotectonics ofthe Ankara Region (NW Central Anatolia). Turkish Association ofPetroleum Geologists Bulletin 3, 43–55.

KOÇY‹⁄‹T, A. 1991c. First Remarks on the Geology of the KarakayaBasin: Karakaya orogen and pre-Jurassic nappes in easternPontides, Turkey. Geologica Romana 27, 3–11.

KOÇY‹⁄‹T, A. 1992. Southward-vergent imbricate thrust fault zone inYuvaköy: a record of the latest compressional event related to thecollisional tectonic regime in Ankara-Erzincan Suture Zone. TABGBulletin 4, 11–118

KOÇY‹⁄‹T, A. 2003. Orta Anadolu’nun genel tektonik özellikleri vedepremselli¤i [General tectonic characteristics and seismicity ofAnkara region]. Turkish Association of Petroleum GeologistsBulletin, Special Publication 5, 1–26 [in Turkish with Englishabstract].

KOÇY‹⁄‹T, A. & ALTINER, D. 1990. Stratigraphy of the Halılar (Edremit-Balıkesir) area: implications for the remnant Karakaya Basin andits diachronic closure. In: SAVAfiÇıN, M.Y. & ERONAT, A.H. (eds),Proceedings of International Earth Sciences Congress on AegeanRegions, 1–6 October, 1990, ‹zmir, 339–352.

KOÇY‹⁄‹T, A. & ALTINER, D. 2002. Tectonostratigraphic evolution of theNorth Anatolian Paleorift (NAPR): Hettangian–Aptian passivecontinental margin of the northern Neotethys, Turkey. TurkishJournal of Earth Sciences 11, 169–191.

KOÇY‹⁄‹T, A., ALTINER, D., FARINACCI, A., NICOSIA, U. & CONTI, S. 1991b.Late Triassic–Aptian evolution of the Sakarya divergent margin:implications for the opening history of the northern Neo-Tethys,in northwestern Anatolia, Turkey. Geologica Romana, XXVII,81–99.

KOÇY‹⁄‹T, A., D‹R‹K, K., ROJAY, B.F., ÖZCAN, E., KAYMAKCı, N. & ÖZÇEL‹K, Y.1991a. ‹negöl-Bilecik-Bozüyük Arasında Kalan Alanın JeolojikEtüdü [Geology of ‹negöl-Bilecik-Bozüyük Region]. ODTÜ-TPAOUygulamalı Arafltırmalar Projesi no. 90-03-09-01-05 [in Turkish,unpublished].

KOÇY‹⁄‹T, A. & LÜNEL, T. 1987. Geology and tectonic setting of Alcıregion, Ankara. METU, Journal of Pure and Applied Sciences 20,35–57.

KOÇY‹⁄‹T, A. ÖZKAN, S. & ROJAY, B.F. 1988. Examples from the forearcbasin remnants at the active margin of northern Neo-Tethys:Development and emplacement ages of the Anatolian Nappe,Turkey. METU, Journal of Pure and Applied Sciences 21,183–210.

KOÇY‹⁄‹T, A., TÜRKMENO⁄LU, A., BEYHAN, A., KAYMAKCı, N. & AKYOL, E.1995. Post- Collisional tectonics of Eskiflehir-Ankara-Çankırısegment of ‹zmir-Ankara-Erzincan Suture Zone (IAESZ): Ankaraorogenic phase. Turkish Association of Petroleum GeologistsBulletin 6, 69–86.

KOÇY‹⁄‹T, A., WINCHESTER, J.A., BOZKURT, E., HOLLAND, G. & BEYHAN, A.2003. Saraçköy Volcanic suite: implications for the subductionalphase of arc evolution in the Galatean Arc Complex, Ankara,Turkey. Geological Journal 38, 1–14.

MOORE, J.C. 1979. Variation in strain and strain rate duringunderthrusting of trench deposits. Geology V, 193–223.

MOORE, J.C. & WHEELER, R.L. 1978. Structural fabric of a mélangeKodiak islands, Alaska. American Journal of Science 278,739–765.

MOORE, G.F. & KARIG, D.E. 1980. Structural Geology of Nias island,Indonesia: implications for subduction zone tectonics. AmericanJournal of Science 280, 193–223.

NEBERT, K. 1958. ‹ç Anadolu’nun en genç jeolojik-tektonik olayıhakkında bir etüd: Ankara vilayetinin (Kayı-Bucak) civarındakiWaallachien orojenez safhasının ispatı [Investigation of theyoungest geologic-tectonic event in central Anatolia: Proof ofWallachien orogenic phase around Ankara (Kayı-Bucak)]. MineralResearch and Exploration Institute of Turkey (MTA) Bulletin 50,16–29 [in Turkish with English abstract].

NELSON, K. 1982. A suggestion for origin of mesoscopic fabric inaccretionary mélange based on features observed in the ChrystallsBeach Complex, South Island, New Zealand. Geological Society ofAmerica Bulletin 93, 625–634.

NORMAN, T. 1972. Stratigraphy of the Upper Cretaceous–Lower Tetriarysequence in Ankara-Yahflihan region. Geological Society of TurkeyBulletin XV, 180–276.

OKAN, Y. 1982. Elmada¤ formasyonunun (Ankara) yaflı ve alt bölümleri[Age and subunits of Elmada¤ formation (Ankara)]. GeologicalSociety of Turkey Bulletin 25, 83–92 [in Turkish with Englishabstract].

OKAY, A. 1984. Kuzeybatı Anadolu’da yer alan metamorfik kuflaklar[Metamorphic belts of northwest Anatolia]. Ketin Simpozyumu,Proceedings, 83–92 [in Turkish with English abstract].

OKAY, A. & MOSTLER, H. 1994. Carboniferous and Permian radiolariteblocks from the Karakaya Complex in northwest Turkey. TurkishJournal of Earth Sciences 3, 23–28.

OKAY, A., TANSEL, ‹. & TÜYSÜZ, O. 2001. Obduction, subduction andcollision as reflected in the Upper Cretaceous–Lower Eocenesedimentary record of western Turkey. Geological Magazine 138,117–142.


458

ROJAY, B. & SÜZEN, L. 1997. Tectonostratigraphic evolution of thecretaceous dynamic basin on accretionary ophiolitic mélangeprism, SW of Ankara region. Turkish Association of PetroleumGeologists Bulletin 9, 1–12.

SANER, S. 1980. The Paleogeographical interpretation of the Mudurnu-Göynük basin based on the depositional features of the Jurassicand later ages. Geological Society of Turkey Bulletin 23, 39-52.

SARAÇ, G. 1994. Ankara Yöresindeki Karasal Neojen ÇökellerininRhinocerotidae (Mammalia-Perissodactyla) Biyostratigrafisi vePaleontolojisi [Rhinocerotidae (Mammalia-Perissodactyla)Biostratigraphy and Palaeontology of Neogene ContinentalSediments Around Ankara]. PhD Thesis, Ankara University,Department of Geological Engineering [in Turkish with Englishabstract, unpublished]

SARAÇ, G. 2003. Türkiye Omurgalı Fosil Yatakları [Mammalian FossilLocalities in Turkey]. General Directorate of Mineral Research andExploration Institute (MTA), Scientific Report no. 10609 [inTurkish, unpublished].

SAYIN, N. 1985. Geology and Petrography of the Northeast ofKaracahasan, Elmada¤ (Ankara-Turkey). MSc Thesis, Middle EastTechnical University, Department of Geological Engineering[unpublished].

SEY‹TO⁄LU, G., KAZANCI, N., KARAKUfi, K., FODOR, L., ARAZ, H. &KARADEN‹ZL‹, L., 1997. Does continuous Compressive Tectonicregime Exist During Late Paleogene to Late Neogene in NWCentral Anatolia, Turkey? Preliminary observations. TurkishJournal of Earth Sciences 6, 77–83.

SEYMEN, ‹. 1975. Kelkit Vadisi Kesiminde Kuzey Anadolu Fay ZonununTektonik Özelli¤i [Neotectonic Characteristics of the NorthAnatolian Fault Zone in Kelkit Valley]. PhD Thesis, ‹stanbulTechnical University, Mining Faculty [in Turkish with Englishabstract].

fiENGÖR, A.M.C. & YILMAZ, Y. 1981. Tethyan evolution of Turkey: a platetectonic approach. Tectonophysics 75, 181–224.

TOKAY, M., LÜNEL, A.T. & KOÇY‹⁄‹T, A. 1988. Geology and Petrology ofthe Gökdere stock of the Orhaniye Syenite, Ankara. METU,Journal of Pure and Applied Sciences 21, 1–37.

TOPRAK, V., SAVAfiÇIN, Y., GÜLEÇ, N. & TANKUT, A. 1996. Structure of theGalatean volcanic province. International Geology Review 38,747–758.

TÜYSÜZ, O. & Y‹⁄‹TBAfi, E. 1994. The Karakaya basin: a palaeotethyanmarginal basin and its age of opening. Acta Geologica Hungarica75, 181–241.

TÜYSÜZ, O., DELLALO⁄LU, A.A. & TERZ‹O⁄LU, N. 1994. A magmatic beltwithin the Neo-Tethyan suture zone and its role in the tectonicevolution of northern Turkey. Tectonophysics 243, 173–191.

WILSON, M., TANKUT, A. & GÜLEÇ, N., 1997. Tertiary volcanism of theGalatia province, North-west central Anatolia, Turkey. Lithos 42,105–121.


459

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

Documents

Ankara Orogenic Phase, Its Age and Transition From ......Gerek katman kutuplar›n›n stereografik izdüﬂümleri, gerekse formasyon içinde ve formasyon kenar faylar› boyunca