Rockfall avalanche deposits associated with normal faulting in the NW of Çanklrl basin: implications for the postcollisional tectonic evolution of the Neo-Tethyan suture zone

The NNE-trending Neo-Tethyan suture zone between Ankara and Çanklrl, thrusts eastward onto different stratigraphic levels of the Neogene succession; however, its western side shows a normal fault relationship. This E-vergent tectonic sliver was inactive during the accumulation of the Miocene–Lower Pliocene sedimentary succession and was created by the movement of the North Anatolian Fault Zone and its splay after the late Pliocene, indicating internal deformation of the Anatolian plate. These results are inconsistent with the previous suggestion that intracontinental convergence related to Neo-Tethyan orogeny continued until the Pliocene (Ankara Orogenic Phase).     

Evolution of an early Eocene pull‐apart basin in the Central Pontides (Northern Turkey): New insights into the origin of the North Anatolian Shear Zone

Although the North Anatolian Shear Zone is one of the main lithospheric‐scale strike‐slip deformation zone in the world, playing a prominent role in the complex geodynamic interaction among the Eurasian, Anatolian and Arabian plates, the onset time of its activity remains highly controversial. Here, we tackle this issue by utilizing nannofossil biostratigraphy on deposits from the Ta?cilar basin, a pull‐apart basin that we have identified inside the North Anatolian Shear Zone overprinting the Intra‐Pontide suture zone. The syn‐tectonic sedimentary succession of the Ta?cilar basin developed completely during the early Eocene (Ypresian; CNE4–CNE5 Zones). The strike‐slip faulting related to the initial onset of the North Anatolian Shear Zone can likely be constrained within the Ypresian, suggesting that the westward escape of the Anatolian plate along the North Anatolian Shear Zone started in the early Eocene.     

Fault kinematic and Plio-Quaternary paleostress evolution of the Bakırçay Basin,Western Turkey

ABSTRACT

At the end of the Cenozoic, western Turkey was fragmented by intense intra-continental tectonic deformation resulting in the formation of two extensional areas: a transtensional pull-apart basin systems in the northwest, and graben systems in the central and southwest areas. The question of the connection of this Late Cenozoic extensional tectonics to plate kinematics has long been an issue of discussion. This study presents the results of the fault slip data collected in Bak?rçay Basin in the west of Turkey and addresses changes in the direction of extensional stresses over the Plio-Quaternary. Field observations and quantitative analysis show that Bak?rçay Basin is not a simple graben basin that has evolved during a single phase. It started as a graben basin with extensional regime in the Pliocene and was transformed into a pull-apart basin under the influence of transtensional forces during the Quaternary. A chronology of two successive extensional episodes has been established and provides reasoning to constrain the timing and location of subduction-related back-arc tectonics along the Aegean region and collision-related extrusion tectonics in Turkey. The first NW–SE trending extension occurred during the Pliocene extensional phase, characterized by slab rollback and progressive steepening of the northward subduction of the African plate under the Anatolian Plate. Western Turkey has been affected, during the Middle Quaternary, by regional subsidence, and the direction of extension changed to N–S, probably in relation with the propagation of the North Anatolian Fault System. Since the Late Quaternary, NE–SW extension dominates northwest Turkey and results in the formation and development of elongated transtensional basin systems. Counterclockwise rotation of Anatolian block which is bounded to the north by the right-lateral strike-slip North Anatolian Fault System, accompanies to this extensional phase.     

Metamorphism of the Central Anatolian Crystalline Complex, Turkey: influence of orogen-normal collision vs. wrench-dominated tectonics on P–T–t paths

The Central Anatolian Crystalline Complex (CACC) is a microcontinent in the Alpine–Himalayan belt. It has previously been considered as a coherent structural entity, but, although the entire CACC is comprised of similar rocks (primarily metasedimentary rocks and granitoids), it consists of at least four tectonic blocks characterized by different P–T–t paths. These blocks are the K?r?ehir (north‐west), Akda? (north‐east), Ni?de (south) and Aksaray (west) massifs. The northern massifs experienced thrusting and folding during collision and were slowly exhumed by erosion; metamorphic rocks are characterized by clockwise P–T paths at moderate P–T and local low‐P–high‐T (LP–HT) overprinting in the highest grade rocks. Apatite fission track ages are Eocene to Oligocene (47–32 Ma). The Aksaray block represents the hot, shallow mid‐crust of a Late Cretaceous–early Tertiary arc. It is dominated by intrusions; rare metapelitic rocks record low‐P (< 4 kbar) regional metamorphism overprinted by LP–HT contact metamorphism. Apatite fission track ages are 50–45 Ma. The Ni?de massif is different from the other CACC blocks because it evolved as a core complex in a wrench‐dominated setting. It is characterized by clockwise P–T paths at moderate P–T followed by widespread LP–HT metamorphism. Apatite fission track ages are Miocene (12–9 Ma), significantly younger than those in the northern massifs. Ni?de rocks resided in the mid‐crust at a time when the rest of the CACC was at or near the Earth's surface. Variations in P–T–t and tectonic histories — especially timing of exhumation — between the northern and southern CACC reflect the difference between head‐on collision vs. mid‐crustal wrenching.     

Formation and emplacement ages of the SSZ‐type Neotethyan ophiolites in Central Anatolia,Turkey: palaeotectonic implications

Isolated outcrops of ophiolitic rocks, termed the Central Anatolian Ophiolites, are found as allochthonous bodies in the Central Anatolian Crystalline Complex, that represent the metamorphosed passive northern edge of the Tauride–Anatolide Platform, central Turkey. In terms of pseudostratigraphic relationships of the magmatic units and their chemical designation, the Central Anatolian Ophiolites exhibit a supra‐subduction zone (fore‐arc) setting within the Vardar–İzmir–Ankara–Erzincan segment of the Neotethys. The epi‐ophiolitic sedimentary cover of the Central Anatolian Ophiolites is generally characterized by epiclastic volcanogenic deep‐sea sediments and debris flows intercalated with pelagic units. The richest and most significant planktonic foraminiferal association recorded from the lowest pelagic members infer a formation age of early–middle Turonian to early Santonian. K/Ar ages of post‐collisional granitoids (81–65 Ma) intruding the basement rocks as well as the Central Anatolian Ophiolites suggest a post‐early Santonian to pre‐middle Campanian emplacement age. The marked high volume of epiclastic volcanogenic sediments intercalated with the pelagics of the Central Anatolian Ophiolite is suggestive of rifting in a marginal sea adjacent to a volcanic arc. Penecontemporaneous tectonism is reflected in repetitions in the stratigraphy and in debris flows, which result from major slides and mass‐gravity reworking of pre‐existing units and of arc‐derived volcanics and sediments. Correlating the rock units and formation/obduction ages of the Central Anatolian Ophiolites with further supra‐subduction zone type ophiolites in the eastern (Turkey) and western (Greece) parts of the Vardar–İzmir–Ankara–Erzincan segment of Neotethys we conclude that the intraoceanic subduction in the east is definitely younger and the closure history of this segment is more complex than previously suggested. Copyright © 2000 John Wiley & Sons, Ltd.     

Late Cretaceous blueschist facies metamorphism in southern Thrace (Turkey) and its geodynamic implications

A blueschist facies tectonic sliver, 9 km long and 1 km wide, crops out within the Miocene clastic rocks bounded by the strands of the North Anatolian Fault zone in southern Thrace, NW Turkey. Two types of blueschist facies rock assemblages occur in the sliver: (i) A serpentinite body with numerous dykes of incipient blueschist facies metadiabase (ii) a well‐foliated and thoroughly recrystallized rock assemblage consisting of blueschist, marble and metachert. Both are partially enveloped by an Upper Eocene wildflysch, which includes olistoliths of serpentinite–metadiabase, Upper Cretaceous and Palaeogene pelagic limestone, Upper Eocene reefal limestone, radiolarian chert, quartzite and minor greenschist. Field relations in combination with the bore core data suggest that the tectonic sliver forms a positive flower structure within the Miocene clastic rocks in a transpressional strike–slip setting, and represents an uplifted part of the pre‐Eocene basement. The blueschists are represented by lawsonite–glaucophane‐bearing assemblages equilibrated at 270–310 °C and ～0.8 GPa. The metadiabase dykes in the serpentinite, on the other hand, are represented by pumpellyite–glaucophane–lawsonite‐assemblages that most probably equilibrated below 290 °C and at 0.75 GPa. One metadiabase olistolith in the Upper Eocene flysch sequence contains the mineral assemblage epidote + pumpellyite + glaucophane, recording P–T conditions of 290–350 °C and 0.65–0.78 GPa, indicative of slightly lower depths and different thermal setting. Timing of the blueschist facies metamorphism is constrained to c. 86 Ma (Coniacian/Santonian) by Rb–Sr phengite–whole rock and incremental ⁴⁰Ar–³⁹Ar phengite dating on blueschists. The activity of the strike–slip fault post‐dates the blueschist facies metamorphism and exhumation, and is only responsible for the present outcrop pattern and post‐Miocene exhumation (～2 km). The high‐P/T metamorphic rocks of southern Thrace and the Biga Peninsula are located to the southeast of the Circum Rhodope Belt and indicate Late Cretaceous subduction and accretion under the northern continent, i.e. the Rhodope Massif, enveloped by the Circum Rhodope Belt. The Late Cretaceous is therefore a time of continued accretionary growth of this continental domain.     

Palaeozoic suturing of eastern and western Tasmania in the west Tamar region: Implications for the tectonic evolution of southeast Australia

A new tectonic model for Tasmania incorporates subduction at the boundary between eastern and western Tasmania. This model integrates thin‐ and thick‐skinned tectonics, providing a mechanism for emplacement of allochthonous elements on to both eastern and western Tasmania as well as rapid burial, metamorphism and exhumation of high‐pressure metamorphic rocks. The west Tamar region in northern Tasmania lies at the boundary between eastern and western Tasmania. Here, rocks in the Port Sorell Formation were metamorphosed at high pressures (700–1400 MPa) and temperatures (400–500°C), indicating subduction to depths of up to 30 km. The eastern boundary of the Port Sorell Formation with mafic‐ultramafic rocks of the Andersons Creek Ultramafic Complex is hidden beneath allochthonous ?Mesoproterozoic turbidites of the Badger Head Group. At depth, this boundary coincides with the inferred boundary between eastern and western Tasmania, imaged in seismic data as a series of east‐dipping reflections. The Andersons Creek Ultramafic Complex was previously thought of as allochthonous, based mainly on associations with other mafic‐ultramafic complexes in western Tasmania. However, the base of the Andersons Creek Ultramafic Complex is not exposed and, given its position east of the boundary with western Tasmania, it is equally likely that it represents the exposed western edge of autochthonous eastern Tasmanian basement. A thin sliver of faulted and metamorphosed rock, including amphibolites, partially separates the Badger Head Group from the Andersons Creek Ultramafic Complex. Mafic rocks in this package match geochemically mafic rocks in the Port Sorell Formation. This match is consistent with two structural events in the Badger Head Group showing tectonic transport of the group from the west during Cambrian Delamerian orogenesis. Rather than being subducted, emplacement of the Badger Head Group onto the Andersons Creek Ultramafic Complex indicates accretion of the Badger Head Group onto eastern Tasmania. Subsequent folding and thrusting in the west Tamar region also accompanied Devonian Tabberabberan orogenesis. Reversal from northeast to southwest tectonic vergence saw imbricate thrusting of Proterozoic and Palaeozoic strata, possibly coinciding with reactivation of the suture separating eastern and western Tasmania.     

Neotectonic evolution of the northwestward arched segment of the Central Anatolian Fault Zone,Central Anatolia,Turkey

Central Anatolia has undergone complex Neotectonic deformation since Late Miocene–Pliocene times. Many faults and intracontinental basins in this region were either formed, or have been reactivated, during this period. The eastern part of central Anatolia is dominated by a NE–SW-trending, left lateral transcurrent structure named the Central Anatolian fault zone located between Sivas in the northeast and west of Mersin in the southwest. Around the central part, it is characterized by transtensional depressions formed by left stepping and southward bending of the fault zone.Pre-Upper Miocene basement rocks of the region consist of the central Anatolian crystalline complex and a sedimentary cover of Tertiary age. These rock units were strongly deformed by N–S convergence. The entire area emerged to become the site of erosion and formed a vast plateau before the Late Miocene. A NE–SW-trending extensional basin developed on this plateau in Late Miocene–Early Pliocene times. Rock units of this basin are characterized by a thick succession of pyroclastic rocks intercalated with calcalkaline–alkaline volcanics. The volcanic sequence is unconformably overlain by Pliocene lacustrine–fluviatile deposits intercalated with ignimbrites and tuffs. Thick, coarse grained alluvial/colluvial fan deposits of marginal facies and fine grained clastics and carbonates of central facies display characteristic synsedimentary structures with volcanic intercalations. These are the main lines of evidence for development of a new transtensional Hırka–Kızılırmak basin in Pliocene times. Reactivation of the main segment of the Central Anatolian fault zone has triggered development of depressions around the left stepping and southward bending of the central part of this sinistral fault zone in the ignimbritic plateau during Late Pliocene–Quaternary time. These transtensional basins are named the Tuzla Gölü and Sultansazlığı pull-apart basins. The Sultansazlığı basin has a lazy S to rhomboidal shape and displays characteristic morphologic features including a steep and stepped western margin, large alluvial and colluvial fans, and a huge composite volcano (the Erciyes Dağı).The geometry of faulting and formation of pull-apart basins can be explained within the framework of tectonic escape of the wedge-like Anatolian block, bounded by sinistral East Anatolian fault zone and dextral North Anatolian transform fault zone. This escape may have been accomplished as lateral continental extrusion of the Anatolian Plate caused by final collision of the Arabian Plate with the Eurasian Plate.     

Late Cenozoic tectonics and stratigraphy of northwestern Anatolia: the effects of the North Anatolian Fault to the region

In northwest Anatolia, there is a mosaic of different morpho-tectonic fragments within the western part of the right-lateral strike-slip North Anatolian Fault (NAF) Zone. These were developed from compressional and extensional tectonic regimes during the paleo- and neo-tectonic periods of Turkish orogenic history. A NE-SW-trending left-lateral strike-slip fault system (Adapazari-Karasu Fault) extends through the northern part of the Sakarya River Valley and began to develop within a N–S compressional tectonic regime which involved all of northern Anatolia during Middle Eocene to early Middle Miocene times. Since the end of Middle Miocene times, this fault system forms a border between a compressional tectonic regime in the eastern area eastwards from the northern part of the Sakarya River Valley, and an extensional tectonic regime in the Marmara region to the west. The extension caused the development of basins and ridges, and the incursions of the Mediterranean Sea into the site of the future Sea of Marmara since Late Miocene times. Following the initiation in late Middle Miocene times and the eastward propagation of extension along the western part of the NAF, a block (North Anatolian Block) began to form in the northern Anatolia region since the end of Pliocene times. The Adapazari-Karasu Fault constitutes the western boundary of this block which is bounded by the NAF in the south, the Northeast Anatolian Fault in the east, and the South Black Sea Thrust Fault in the north. The northeastward movement of the North Anatolian Block caused the formation of a marine connection between the Black Sea and the Aegean/Mediterranean Sea during the Pleistocene.     

New field and seismic data about the intraplate strike-slip deformation in Van region,East Anatolian plateau,E. Turkey

The study area is the Van earthquake region. It is located in the western section of the East Anatolian–Iranian plateau outside and to the east of the Karlıova triple junction. Based on the tectonic periods, the rock units exposed in the study area are classified into two common categories. These are the Pre-Late Pliocene paleotectonic units and the Plio-Quaternary neotectonic units. The Paleotectonic units are composed of the Yüksekova Complex of Campanian–Maastrichtian age and the Kırkgeçit Formation of Oligo-Miocene age. The paleotectonic units are intensely deformed (folded, thrust to reverse faulted and converted into an imbricate stack). The neotectonic units are composed of fluvio-lacustrine sedimentary facies with volcanic interclations. It is full of soft-sedimentary structures such as deltaic structure, slump fold, sand dikes to sills and normal to reverse types of growth faults which imply to a sedimentation accompanied by both a volcanic activity and active tectonics. Originally the Paleotectonic units are overlain with an angular unconformity by the nearly flat-lying neotectonic units. This angular unconformity and the big difference in the deformational patterns of both categories of rock units indicate an inversion in tectonic regime in Late Pliocene. The new tectonic regime is the strike-slip faulting-dominated neotectonic regime. It is governed by an approximately N–S-directed compression, and composed of NW- to NE-trending strike-slip faults, N–S trending oblique-slip normal faults to fissures and the E–W trending thrust to reverse faults. Most of thrust to reverse faults are inherited from the Pre-Late Pliocene paleotectonic regime. Some of them have reactivated and led to the occurrence of large and devastative earthquakes. The last devastative seismic event is the 23 October 2011 Tabanlı (Van) earthquake of Mw = 7.2 that caused 644 deaths and moderate to heavy damage of ¼ of structures (28,532) in Van earthquake region. The source of the Tabanlı earthquake is the Everek erosional reverse fault. In addition the Tabanlı earthquake is the largest seismic event occurred till now in Turkey. It was followed by a series (over 6000) of small-sized aftershocks and severeal moderate-sized indepentent earthquakes of reverse, normal and strike-slip faulting origin. Both the field and new seismic data strongly reveal that the prominent tectonic regime in the East Anatolian plateau is the strike-slip neotectonic regime, not the tensional tectonic regime as has been reported in some previous works. The strike-slip faulting and related deformation are confined into the upper shallowing part (up to 40 km) of the crust, whilst the extensional deformations are the subcrustal processes and being taking place in a squashy zone at the depths of approximately 40–60 km.     

The termination of the North Anatolian Fault System (NAFS) in Eastern Turkey

ABSTRACT

The present-day tectonic framework of Turkey comprises mainly two strike-slip fault systems, namely dextral North Anatolian and sinistral East Anatolian faults. They are considered as the main cause of deformation patterns in Anatolia. These two mega shear systems meet at Kargapazar? village of Karl?ova county. The area to the east of the junction has a transpressional tectonic regime between the Eurasian and Arabian plates and is characterized, based on field observation, by a network of faults defining a typical horsetail splay structure. The horsetail splay is interpreted as marking the termination of the North Anatolian Fault System (NAFS), which continues eastward into the Varto Fault Zone (VFZ) and then dies out. The present study reveals that the VFZ is made up of two main parts, namely the principal displacement zone (PDZ) and the transpressional splay zone (TPSZ), both characterized by the right-lateral strike-slip with reverse motion. However, the area to the east of Varto is characterized dominantly by reverse-thrust faults and E–W-trending faults as shown by focal mechanism solutions. The generation of the VFZ as a transpressional termination to the NAFS can be related directly to the block movements of the Eurasian, Anatolian, and Arabian plates.     

Zircon U–Pb Geochronology and Petrogenesis of Early–Midlle Permian Arc–Related Volcanic Rocks in Central Jilin: Implications for the Tectonic Evolution of the Eastern Segment of Central Asian Orogenic Belt

This paper presents age and geochemical data of a recently identified Late Paleozoic volcanic sequence in central Jilin Province, with aims to discuss the petrogenesis and to constrain the tectonic evolution of the Central Asian Orogenic Belt in this area. Firstly, the volcanic rocks have zircon U-Pb ages of 290–270 Ma. Secondly, they are characterized by(a) ranging in composition from the low-K tholeiite series to high-K calc-alkaline series;(b) enrichment in light rare earth elements and depletion of heavy rare earth elements, with negative Eu anomalies; and(c) negative Nb, Ta, and Ti anomalies. Finally, the volcanic rocks yield εHf(t) values of +7.1 to +17. These data suggest that the central Jilin volcanic rocks were possibly derived from predominant partial melting of a depleted lithospheric mantle that might have been modified by subducted slab–derived fluids. Combined with previous studies, the Late Paleozoic–Early Mesozoic magmatism in Central Jilin can be divided into two stages:(a) a volcanic arc stage(290–270 Ma) represented by low-K to high–K, tholeiite to calc–alkaline plutons and(b) a syn–collisional stage(260–240 Ma) represented by high-K calc–alkaline I-type granites. Furthermore, the timing and the tectonic setting of the above magmatic rocks show that the arc was probably produced by the northward subduction of the Paleo-Asian Ocean and that the final closure of the Paleo-Asian Ocean occurred prior to the Early Triassic.     

Stratigraphical correlation of the Late Jurassic Lourinhã Formation in the Consolação Sub‐basin (Lusitanian Basin), Portugal

The c. 700 m thick succession of continental–brackish‐marine deposits forming the Lourinhã Formation, cropping out along the coast of western Portugal between Baleal and Santa Cruz, has been correlated using laterally persistent shelly marker beds. Three shelly units record the episodic establishment of relatively short‐lived, brackish‐marine embayments, transgressing from the southwest, onto a low‐lying coastal plain. The succession displays systematic changes in facies types and stacking patterns reflecting differences in fluvial style, bedload character and palaeontological content. Based on these observations, four new members for the Lourinhã Formation are proposed: the Sáo Bernardino, Porto de Barças, Areia Branca and Ferrel members. New biostratigraphical data indicate that the Lourinhã Formation is Late Kimmeridgian to earliest Early Tithonian in age. This age has also been obtained from the underlying mixed carbonate and clastic deposits of the Abadia Formation at Consolação. As a result, these latter sediments are now re‐assigned to the Alcobaça Formation, a lithostratigraphical term currently in use in other areas of the Lusitanian Basin. Improved regional mapping of the Lourinhã Formation has established a new sub‐basin within the western parts of the Lusitanian Basin. This sub‐basin, now named the Consolação Sub‐basin, is bounded to the east by the Lourinhã–Caldas de Rainha (L–C) fault zone and to the west by the Berlengas Horst. Copyright © 2013 John Wiley & Sons, Ltd.     

Zircon U‐Pb age,Trace Element,and Hf Isotopic Compositions of Nordmarkite in the Lizhuang Rare Earth Element Deposit in the Western Margin of the Yangtze Block

The Mianning–Dechang(MD) rare earth element(REE) belt, located in the northern Kangdian axis(KDA) in the western margin of the Yangtze platform, is one of the most economically significant REE mineral belts in China. REE mineralization is associated with Himalayan carbonatite–alkaline complexes. The Lizhuang nordmarkite occurred in the northern part of the MD REE belt. The majority of zircons from the Lizhuang nordmarkite are characterized by pronounced positive Ce yet slightly negative Eu anomalies and high U/Yb. Moreover, all zircons have stable Hf isotopic compositions with initial ~(176) Hf/(~(177)Hf) ratios ranging from 0.282739 to 0.282808 and an average value of 0.282773. The negative Lu/Hf and positive ε_(Hf)(t) range from-0.98 to-0.94(average value of-0.96) and from-0.56 to 1.89(the majority is positive, with an average of 0.66), respectively. These characteristics indicate that the rock is derived from an enriched mantle and subducted material. LA-ICP-MS analysis of the zircons from the intrusion yields a weighted mean ~(206)Pb/(~(238)U) age of 28.57±0.61 Ma. During this period, the tectonic activity in the KDA is not plate subduction but an intraplate tectonic exhibiting fold–thrust and strike–slip behaviors in the western marginal zone of the Yangtze platform(WMYB). We suggest the possibility of an existing eastward old slab subduction under WMYB combined with a regional tectonic evolution. The Lizhuang nordmarkite may be derived from an enriched mantle beneath the western part of the Yangtze craton, which originated from the remelting of the Tethys subducting slab, because of the Himalayan strike–slip that formed a special type of REE deposit called strike–slip-type REE deposits.     

A Miocene onset of the modern extensional regime in the Isparta Angle: constraints from the Yalvaç Basin (southwest Turkey)

The pre-Neogene Tauride fold-and-thrust belt, comprising Cretaceous ophiolites and metamorphic rocks and non-metamorphic carbonate thrust slices in southern Turkey, is flanked and overlain by Neogene sedimentary basins. These include poorly studied intra-montane basins including the Yalvaç Basin. In this paper, we study the stratigraphy, sedimentology and structure of the Yalvaç Basin, which has a Middle Miocene and younger stratigraphy. Our results show that the basin formed as a result of multi-directional extension, with NE–SW to E–W extension dominating over subordinate NW–SE to N–S extension. We show that faults bounding the modern basin also governed basin formation, with proximal facies close to the basin margins grading upwards and basinwards into lacustrine deposits representing the local depocentre. The Yalvac Basin was a local basin, but a similar, contemporaneous history recently reconstructed from the Alt?napa Basin, ~100 km to the south, shows that multi-directional extension dominated by E–W extension was a regional phenomenon. Extension is still active today, and we conclude that this tectonic regime in the study area has prevailed since Middle Miocene times. Previously documented E–W shortening in the Isparta Angle along the Aksu Thrust, ~100 km to the southwest of our study area, is synchronous with the extensional history documented here, and E–W extension to its east shows that Anatolian westwards push is likely not the cause. Synchronous E–W shortening in the heart and E–W extension in the east of the Isparta Angle may be explained by an eastwards-dipping subduction zone previously documented with seismic tomography and earthquake hypocentres. We suggest that this slab surfaces along the Aksu thrust and creates E–W overriding plate extension in the east of the Isparta Angle. Neogene and modern Anatolian geodynamics may thus have been driven by an Aegean, Antalya and Cyprus slab segment that each had their own specific evolution.     

Field evidence for normal fault linkage and relay ramp evolution: the Kırkağaç Fault Zone,western Anatolia (Turkey)

Linking of normal faults forms at all scales as a relay ramp during growth stages and represents the most efficient way for faults to lengthen during their progressive formation. Here, I study the linking of normal faulting along the active K?rka?aç Fault Zone within the west Anatolian extensional system to reconstruct fault interaction in time and space using both field- and computer-based data. I find that (i) connecting of the relay zone/ramp occurred with two breaching faults of different generations and that (ii) the propagation was facilitated by the presence of pre-existing structures, inherited from the ?zmir-Bal?kesir transfer zone. Hence, the linkage cannot be compared directly to a simple fault growth model. Therefore, I propose a combined scenario of both hangingwall and footwall fault propagation mechanisms that explain the present-day geometry of the composite fault line. The computer-based analyses show that the approximate slip rate is 0.38 mm/year during the Quaternary, and a NE–SW-directed extension is mainly responsible for the recent faulting along the K?rka?aç Fault Zone. The proposed structural scenario also highlights the active fault termination and should be considered in future seismic hazard assessments for the region that includes densely populated settlements.     

Petrogenesis of the ü?kap?l? Granitoid and its Mafic Enclaves in Elmal? Area (Ni?de, Central Anatolia, Turkey)

The Late Cretaceous ükapili Granitoid including mafic microgranular enclaves intruded into metapelitic and metabasic rocks, and overlain unconformably by Neogene ignimbrites in the Ni de area of Turkey. It is mostly granite and minor granodiorite in composition, whereas its enclaves are dominantly gabbro with a few diorites in composition. The ükapili Granitoid is composed mainly of quartz, K-feldspar, plagioclase, biotite, muscovite and minor amphibole while its enclaves contain mostly plagioclase, amphibole, minor pyroxene and biotite. The ükapili Granitoid has calcalkaline and peraluminous (A/CNK= 1.0-1.3) geochemical characteristics. It is characterized by high LILE/HFSE and LREE/HREE ratios ((La/Lu) N = 3-33), and has negative Ba, Ta, Nb and Eu anomalies, resembling those of collision granitoids. The ükapili Granitoid has relatively high 87Sr/86Sr (i) ratios (0.711189-0.716061) and low εNd (t) values (-5.13 to -7.13), confirming crustal melting. In contrast, the enclaves are tholeiitic and metaluminous, and slightly enriched in LILEs (K, Rb) and Th, and have negative Ta, Nb and Ti anomalies; propose that they were derived from a subduction-modified mantle source. Based on mineral and whole rock chemistry data, the ükapili granitoid is H-(hybrid) type, post-collision granitoid developed by mixing/mingling processes between crustal melts and mantle-derived mafic magmas.     

A case for a downwasting mountain glacier during Termination I,Verçenik valley,northeastern Turkey

Field evidence of palaeoglacial records in the Verçenik valley in the Eastern Black Sea Mountains was examined and 19 samples for surface exposure dating with cosmogenic ¹⁰Be were collected with the aim of increasing knowledge on the amplitude and frequency of palaeoglacier advances in Anatolia. Glacial erosional features were mapped and the flow directions of the palaeoglaciers were determined. The Verçenik palaeoglacier advanced before 26.1 k ± 1.2 k yr. The Last Glacial Maximum (LGM) advance continued until 18.8 k ±1.0 k yr. The Verçenik palaeoglacier collapsed during Termination I. After 17.7 k ± 0.8 k yr there was no more ice in the main valley. The Verçenik palaeoglacier most probably then separated into five small glaciers that were restricted to the tributary valleys. Among these, the Hem?in palaeoglacier completed its recession around 15.7 k ± 0.8 k yr. On the basis of glacial erosion features, a Lateglacial glacier advance can be identified. Evidence of the Little Ice Age advance appears to be absent. The results from this valley system seem to be consistent with the first results from the adjacent Kavron valley and with the Anatolian LGM palaeoclimate, the sea surface temperature minima in the western Mediterranean, the deposition of red clay layers in the Black Sea and deposition of the Heinrich‐1 layer in the North Atlantic. Copyright © 2007 John Wiley & Sons, Ltd.     

Assessment of water quality and pollution of the Lake Seyfe basin, Kırşehir, Turkey

Lake Seyfe is located in a closed basin near K?r?ehir in the central Anatolian region, Turkey. The aim of this study is to evaluate the groundwater quality and effects of lithogenic contamination carried out in the Lake Seyfe basin, which is represented by various lithologies and groundwater types. Seyfe, Horla and Akp?nar springs are recharged through marbles at the western and southwestern of the basin are ultimately and discharged into the K?z?l?rmak Formation and Lake Seyfe. The waters of deep wells drilled into the marbles are of bicarbonate type (type I) in the Ca²⁺–Mg²⁺–HCO₃ ^? and Ca²⁺–HCO₃ ^? facies. Özlühüyük spring and waters from most of trenches and shallow wells, which are fed by the K?z?l?rmak Formation, have a mixed (type II) composition in the Ca²⁺–Mg²⁺–HCO₃ ^?–Cl^? facies. Groundwater in the alluvium and K?z?l?rmak Formation along Lake Seyfe has a salty (type III) character in the Na⁺–Cl^? facies. The main reasons of formation and change of the groundwater salinity and hydrochemical facies in the Seyfe basin are causing the various (a) lithogenic pollution and heterogeneity of the K?z?l?rmak Formation, (b) salinity of the upper soil zones, and (c) evaporation of the trench and channel waters open to the atmosphere. Considering parameters such as sodium hazard, specific conductivity, bicarbonate and carbonate hazards, waters in the study area are generally suitable for agricultural usage.