Browsing by Author "Gulyuz, Erhan"

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Age and Kinematics of the Burdur Basin: Inferences for the Existence of the Fethiye Burdur Fault Zone in Sw Anatolia (Turkey)
(Elsevier, 2018) Ozkaptan, Murat; Kaymakci, Nuretdin; Langereis, Cor G.; Gulyuz, Erhan; Ozacar, A. Arda; Uzel, Bora; Sozbilir, Hasan
The Burdur Basin is a late Miocene to Pliocene fluvio-lacustrine basin in SW Anatolia. It is developed within the postulated Fethiye-Burdur Fault Zone, which was argued to be a sinistral strike-slip fault zone developed in response to propagation of the Pliny-Strabo STEP fault into SW Anatolia (Turkey). In order to assess the presence and tectonic characteristics of the fault zone, we conducted a paleomagnetic study in the Burdur basin that involved rock magnetic experiments, Anisotropy of Magnetic Susceptibility (AMS) measurements and developing a magnetostratigraphy for dating purposes. The obtained age model constrains most part of the tectonic evolution of the basin. The well exposed (similar to 270 m thick) Burdur section revealed 3 normal and 2 reverse polarity magnetozones. We propose that the Burdur Formation spans most of the Gauss Chron (similar to 3.4-2.5 Ma) which implies a sedimentation rate of > 18 cm/kyr. The AMS results in the section indicate NW-SE directed extension. In addition, we have also conducted kinematic analyses from 1790 fault slip data collected at 44 sites distributed within the supposed Fethiye Burdur Fault Zone in the region. The results indicate that the region has been developed under a NW-SE directed extensional deformation regime and was dominated by NE-SW striking normal faults from late Miocene to recent. Few NW-SE striking normal faults with strike-slip components are categorized as transfer faults, which accommodated differential stretching between the Burdur and Cameli basins. Stretching amounts increase southwards demonstrating a dextral transtensional character of the transfer faults. We have not observed any significant strike-slip motion along the NE-SW striking faults, which challenges the presence and sinistral transcurrent nature of the supposed Fethiye Burdur Fault Zone.
Apatite Fission Track Dating of the Beypazari Granitoid: Insight for the Inception of Collision Along the Northern Neotethys, Turkey
(Taylor & Francis Ltd, 2020) Gulyuz, Erhan
The Beypazari Granitoid is an arc-related intrusion in the Central Pontides, Turkey. This study presents apatite fission track (AFT) ages of the intrusion to shed some light on collision-related cooling/exhumation history of the central Pontides. The AFT ages from different altitudes (506-805-1110 metres above sea level) of the Beypazari Granitoid yield around 65 +/- 3 Ma. This indicates a rapid cooling/exhumation for the intrusion around 65 Ma, which is attributed to the commencement of the collision event in the region. Integration of these ages and low-temperature thermochronology literature suggests a progressive collision propagation towards the margins of the collision system.
Deformation in Sw Anatolia (Turkey) Documented by Anisotropy of Magnetic Susceptibility Data
(Amer Geophysical Union, 2021) Ozkaptan, Murat; Gulyuz, Erhan; Uzel, Bora; Langereis, Cor G.; Ozacar, A. Arda; Kaymakci, Nuretdin
Convergence between the Eurasian and the African plates in the West Anatolian-Aegean region results in a trench retreat due to slab roll-back and tearing of the subducted African lithosphere. The upper plate response of this process gave way to back-arc extension in the region. We have conducted a very detailed anisotropy of magnetic susceptibility (AMS) study on the Neogene rocks in SW Anatolia to unravel the style and magnitudes of deformation. For this purpose, from 83 sites in 11 structurally homogeneous domains, 1,680 paleomagnetic samples were analyzed. The results show that AMS fabrics are related to the tectonic deformation and that the magnetic lineation (maximum susceptibility axis, k(1)) is parallel to inferred maximum extension, while minimum susceptibility (k(3)) is typically normal to the bedding plane, corresponding to a preserved compaction associated with deposition fabric. The intermediate axis (k(2)) is parallel to a second extension direction and indicates that the region has been under the control of multi-directional extension during the Neogene. Two main magnetic lineation directions are identified and represent Oligocene to middle Miocene E-W, and late Miocene to Pliocene NW-SE oriented extension. The magnetic lineation directions are dominantly parallel or perpendicular to the general strikes of the normal faults. The results show that the deformation in the region resembles two differentially stretched rubber sheets under the influence of SW oriented extension, exerted by the southward retreating Eastern Mediterranean subduction system.
The Geo/Thermochronology of Dismal Island (Marguerite Bay, Antarctic Peninsula)
(Tubitak Scientific & Technological Research Council Turkey, 2023) Karaoglan, Fatih; Karatas, Burcu; Ozdemir, Yavuz; Gulyuz, Erhan; Vassilev, Oleg; Selbesoglu, Mahmut Oguz; Gildir, Semih
Dismal Island is located at the entrance of Marguerite Bay between Adelaide Island to the northeast and Alexander Island to the southwest within the Antarctic Peninsula (AP). Its unique position between Alexander and Adelaide islands provides the opportunity to perform testing and link these regions through Cenozoic magmatism and tectonics due to the subduction of the Pacific plate beneath the AP along the northern margin. Dismal Island was visited in February 2021 within the framework of the sixth Turkish Antarctic Expedition (TAE-VI). Thirteen samples were collected for petrography, geochronology, and low-temperature thermochronology (LTT). Of the samples, 3 were dated using laser ablation-inductively coupled plasma-mass spectrometer zircon U-Pb geochronology, 2 were dated using apatite fission-track (AFT) analysis, and 1 was dated using apatite uranium-thorium-helium (U-Th/He) (AHe) thermochronology. The island comprises massif quartz-diorite, tonalite, mafic, and felsic dikes, indicating a hybrid magma source. The 3 zircon U-Pb ages yielded a crystallization age of 47-48 for the magmatic body. The AFT ages yielded a cooling age of 41 Ma, suggesting either a shallow emplacement at a depth of similar to 4 km or an uplift/exhumation during middle-late Eocene boundary. In contrast, the AHe age of 1 sample was 20.1 +/- 1.1 Ma, together with a fast-cooling profile during the same period, which indicated an early Miocene uplift in the region. Similar early-middle Eocene crystallization ages within similar rock outcrops were determined on Adelaide and Alexander islands, Adelaide Island Intrusive Suite. The AFT ages obtained in this study (similar to 41 Ma), close to formation age, were also found on Adelaide and Alexander islands. The (LTT) literature of the region shows that the LTT ages get younger to the north along the AP, reflecting the northward migration of the ridge-trench collision and opening of the slab window along the western coast of the AP. The AHe age and the fast-cooling profile suggested that the ridge-subduction between the Tula and Adelaide fracture zones to the north of Dismal Island reached the region during Aquitanian-Burdigalian.
Geological and Mineralization Characteristics of the Kestanelik Epithermal Au-Ag Deposit in the Tethyan Metallogenic Belt, Nw Turkey
(Geological Society Korea, 2020) Gulyuz, Nilay; Gulyuz, Erhan; Shipton, Zoe K.; Kuscu, Ilkay; Lord, Richard A.
Kestanelik epithermal gold deposit is situated in the Biga Peninsula, which hosts numerous metallic deposits belonging to the Tethyan Metallogenic Belt. In the Biga peninsula the Tethyan Metallogenic Belt is represented by a Neo-Tethyan suture zone. Discovered deposits along the belt are commonly associated with Cenozoic magmatism ranging between 52 and 18 Ma in age, formed due syn- to post-collisional tectonics. In this study, we focus on the deposit-scale geological and mineralization characteristics of Kestanelik in order to determine the formation and evolution of the deposit within the tectono-magmatic history of the Biga Peninsula. We (1) mapped the geology of the deposit area (2) conducted paleostress analyses, (3) observed and examined the macroscopic and petrographical textural, mineralogical and alteration characteristics of the mineralization and (4) interpreted geophysical resistivity survey and geochemical assay data. The stratigraphic age of the Kestanelik deposit, bracketed by cross cutting relations and supported by the geophysical data, is middle Lutetian-early Priabonian which also implies that the deposit has a genetic link with the Cenozoic post-collisional calc-alkaline magmatism. A NE-SW oriented compressional regime determined from the paleostress analyses is consistent with the kinematics of the vein system and is attributed to the collision and further convergence after the closure of the northern branch of the Neo-Tethys Ocean. The fracture system provided structural pathways for the transport of the hydrothermal fluids. The common presence of pseudo-bladed quartz and hydrothermal breccias, and the low total sulphide and base metal contents in the mineralized veins indicate that the Kestanelik is a low sulphidation epithermal-type gold deposit. Boiling, mixing (hypogene oxidation) and supergene enrichment are the likely gold deposition and enrichment processes respectively.
Geomorphological and Geo/Thermo-chronological Responses of Indian Plate's Deformation During Neogene- Quaternary Time Along the Eastern Himalayan Syntaxis: Formation of Manabhum Anticline
(Pergamon-elsevier Science Ltd, 2024) Goswami Chakrabarti, Chandreyee; Gulyuz, Erhan; Gulyuz, Nilay; Narzary, Belligraham; Jaiswal, Manoj K.; Karaoglan, Fatih
India-Eurasia and India-Burma collision systems encircle Eastern Himalayan Syntaxis (EHS) in the north and the southeast. The main active structure responsible for the uplift of the Quaternary and Neogene rocks in the easternmost part of the EHS is the NW-SE trending Mishmi Thrust (MT). The spectacular antiformal Manabhum Hill developed during the Quaternary as a ramp antiform over a splay of Mishmi Thrust in its foreland region. The current work presents the deformation scenario, uplift rate, and landform development along the Mishmi Thrust from the Neogene to the Recent for the first time. The surface deformation and the rock and sediment deformation histories have been interpreted from the geomorphology, structure and petrology of the rocks and sediments. We use new (U + Th + Sm)/He low-temperature thermochronology (LTT) of zircon and apatite and Optically Stimulated Luminescence (OSL) dates to calculate the uplift rate for the Neogene to early Quaternary and late Quaternary time intervals, respectively. The Neogene uplift rate varies between 0.91 and 2.3 mm/yr, whereas the early Quaternary uplift rate is similar to 3.1 mm/yr. The increased uplift rate during the Quaternary period with significant deformation of sediments indicates the non-rigid character of the Indian plate in this sector, which experienced compression and clockwise rotation.
Giant Tufas of Lake Van Record Lake-Level Fluctuations and Climatic Changes in Eastern Anatolia,turkey
(Elsevier, 2019) Yesilova, Cetin; Gulyuz, Erhan; Huang, Ci-Rong; Shen, Chuan-Chou
Lake Van, the largest soda lake in the world, is a key area where climatic changes are recorded by well-preserved sedimentary successions. In spite of the existence of such sequences, the ancient lake levels are still under debate. Here, we present U/Th ages of tufa layers exposed along the northern margin of the lake near the town of Adilcevaz. Tufa are interpreted to form during humid and temperate climate conditions in the contact zone between the highly alkaline lake water - rich in bicarbonate and carbonate ions - and calcium-rich groundwater. These contact zones most likely appear near shore. Thus, U/Th ages and altitude of the tufa present minimum ancient lakestands. The tufas obtained in our study are dated between 112.7 and 19.3 ka. They are interpreted to record two transgressional intervals, the first starting at 1701 meters above sea level (masl) altitude at 112.7 ka reaching 1706 masl at 72.5 ka (based on three U/Th ages). The second transgression starts at the present Lake Van level of 1646 masl at 30.1 ka, reaching 1725 masl at 19.3 ka (based on 15 U/Th ages). Comparison with climate proxies reveals that the first transgression was caused by intensified precipitation accompanied by warming, while the second transgression was triggered mainly by warming that initiated melting of glaciers. The lake-level fluctuations described here are almost in line with the ones gathered from dated lake terraces but contradict lake-level reconstruction based on pore water salinity.
Kinematic and Thermal Evolution of the Haymana Basin, a Fore-Arc To Foreland Basin in Central Anatolia (Turkey)
(Elsevier, 2019) Gulyuz, Erhan; Ozkaptan, Murat; Kaymakci, Nuretdin; Persano, Cristina; Stuart, Finlay M.
Gondwana (Tauride/kirsehir blocks) and Eurasia (Pontides) derived continental blocks delimit the Haymana basin, central Turkey, to the south and the north, respectively. The boundaries of these blocks define the IzmirAnkara-Erzincan and Intra-Tauride Suture zones which are straddled by a number of Late Cretaceous to Oligocene marine to continental basins. The Haymana Basin is located at the junction of the IAESZ and ITSZ and comprises Upper Cretaceous to Middle Eocene basin infill deposited in response to the interaction of these blocks. The basin provides a unique opportunity to unravel spatio-temporal relationships related to the timing of late stage subduction history of Neo-Tethys Ocean and subsequent collision of the intervening continental blocks. We have conducted a multidisciplinary study in the region that includes mapping of major structures combined with fault kinematic analyses. E-W striking folds dominate the basin, cross-section balancing of these structures indicates around 25% roughly N-S shortening in the region. Paleostress studies indicate that the basin was initially subjected to N-S to NNE-SSW extension until the middle Paleocene (phase 1) and then N-S directed syn-depositional compression and coeval E-W directed extension until the middle Miocene (phase 2) implying strike-slip deformation and pure shear shortening in the basin. These different deformation phases are attributed to first fore-arc (subduction) basin development then foreland (collision) stages of the basin. Apatite (U-Th)/He dating of 5 samples indicate that exhumation of the SE segment of the basin started in early Oligocene, whereas the NW segment of the basin exhumed in the early Miocene. The differential uplift is possibly related to progressive north-westwards movement of Derekby basin bounding fault at the north. We propose that the Haymana basin evolved from extensional forearc basin during the late Cretaceous to early Paleocene and foreland basin after the terminal subduction and subsequent collision of Tauride and Pontide blocks.
Low Temperature Thermochronology Reveals Tilting of Crystalline Bodies, Halilaga Porphyry Cu-Au Deposit, Nw Anatolia: Implications for Exploration of Porphyry Copper Deposits and Interpretation of Low-Temperature Thermochronology Data for Regional Tectonics
(Elsevier, 2024) Gulyuz, Nilay; Gulyuz, Erhan; Karaoglan, Fatih; Kuscu, Ilkay
Because most crystalline bodies lack intrinsic paleo-horizontal information, their tilting cannot be measured directly. Their vertical movement, however, may be tracked by low-T thermochronology (LTT) tools. Because tilting is caused by differential vertical movements, it can be understood if the rate of differential movements is determined. In this regard, here we apply a new LTT-based approach to calculate the orientation of a tilted crystalline body, the Halilaga Cu-Au deposit, in NW Anatolia. Orientation is consistent with the one calculated from a drillhole-based 3D model of the deposit. This reveals the significance of tilting calculations for the exploration of porphyry Cu deposits. On the other hand, and more importantly, it emphasizes the importance of tilting calculations for geological applications such as LTT-based exhumation histories of samples taken from vertical profiles, and paleomagnetic studies. AHe data from the Halilaga deposit reveals the earliest response to the Aegean back-arc extension at similar to 24 Ma in the north of Western Anatolia. Lastly, thermal models, the new complementary datasets for the tectonic evolution of the region, show that the Halilaga deposit was exhumed to the surface by the coupling effects of Aegean extension and westward propagation of the North Anatolian Fault, which occurred not earlier than 2 Ma.
Low-Temperature Thermochronology Records the Convergence Between the Anatolide-Tauride Block and the Arabian Platform Along the Southeast Anatolian Orogenic Belt
(Mdpi, 2024) Gildir, Semih; Karaoglan, Fatih; Gulyuz, Erhan
SE Anatolia is witnessing the final stage of the Wilson Cycle, where a continental collision between the Tauride-Anatolide block and Arabian platform occurred, and a 1.5 km Eastern Tauride mountain chain formed. We present new low-temperature thermochronology (LTT) ages, including eight apatite fission track (AFT) and seven apatite and zircon U-Th-Sm/He (AHe, ZHe) ages, for the metamorphic rocks from the Nappe Zone of the Southeast Anatolian Orogenic Belt. The ZHe ages vary from 51.2 +/- 0.7 Ma to 30.4 +/- 0.6 Ma, the AFT ages range from 33.1 +/- 1.6 Ma to 18.1 +/- 0.9 Ma, and the AHe ages range from 23.6 +/- 2.5 Ma to 6 +/- 1.9 Ma. The LTT data show a continuous slow uplift of the region. However, the thermal modeling results suggest an Eocene and middle-late Miocene fast uplift of the region. Similar to our results, the LTT studies along the SAOB show that the vertical movements initiated during the Eocene period have continued in a steady-state regime to recent times. The Eocene epoch is identified by arc-back-arc setting in the region, whereas the Miocene epoch is marked by the continental collision. Within this tectonic framework, vertical movements on the overriding plate are controlled by both extensional and compressional tectonics. The LTT data obtained along the SAOB show fingerprints of thrust propagation from north to south.
Neogene Kinematics of the Potwar Plateau and the Salt Range, Nw Himalayan Front: a Paleostress Inversion and Ams Study
(Taylor & Francis inc, 2022) Qayyum, Abdul; Poesse, Jorik Willem; Kaymakci, Nuretdin; Langereis, Cornelis G.; Gulyuz, Erhan; Ahsan, Naveed
We provide new kinematic data from the Potwar Plateau (Pakistan) to evaluate the tectonic evolution of the region during the Neogene. The plateau is bound by two major strike-slip faults in the west and the east, accommodating its southwards translation. We have recognized two Neogene deformation phases in the plateau, based on paleostress inversion and Anisotropy of Magnetic Susceptibility (AMS) tensors. The first phase lasted until the early Pliocene and was characterized by vertical minor stress and N-S compression, implying thrust tectonics. The second deformation phase is characterized by a near-vertical intermediate principal stress and near-horizontal major and minor stresses, interpreted to be associated with strike-slip tectonics since the late Pliocene. K-int vectors from 21 sites are relatively compatible with the major principal stress orientations (sigma(1)) and indicate two distinct domains. This is possibly because K-min orientations are related to compaction, whereas K-int orientations were always parallel to tectonic shortening and hence compression direction during both strike-slip (post-late Pliocene) and thrusting (pre-late Pliocene) phases. These phases are characterized by swapping of (sigma(2)) and (sigma(3)) orientations while (sigma(1)) maintained its orientation. The most prominent change occurs at the western part of the Potwar Plateau, where major principal stress directions (sigma(1)) and K-int axes fan out south-westwards. The eastern domain is dominated by NE-SW trending folds and thrust faults, which are absent in the western domain. These structural features are interpreted to be the result of the distribution of deposits of the Neoproterozoic Salt Range Formation as a substratum below the Potwar Plateau. The Salt Range Formation is very thick and widespread in the west area and almost absent in the east. This factor led to unconstrained southwards gliding of the Potwar Plateau over the salt deposits in the west as opposed to frictional sliding and substantial internal deformation in the east.
Paleomagnetic Evidence for Upper Plate Response To a Step Fault, Sw Anatolia
(Elsevier Science Bv, 2018) Kaymakci, Nuretdin; Langereis, Cor; Ozkaptan, Murat; Ozacar, A. Arda; Gulyuz, Erhan; Uzel, Bora; Sozbilir, Hasan
Pliny-Strabo Trench is a Subduction Transform-Edge Propagator (STEP) Fault developed on the northern edge of the subducted African Oceanic Lithosphere. It connects the Aegean and Cyprian trenches in the Eastern Mediterranean convergent system. Although, deep geometry of the STEP fault and associated slab tear in mantle are imaged, its shallow vertical and lateral continuation in the crust and impact on the over-riding plate are still unknown. Thus, we have studied SW Anatolia, the candidate site where this structure could propagate laterally and vertically, for its vertical axis rotations using paleomagnetic tools. In this study, more than 2000 paleomagnetic samples were collected and analysed from 86 different sites which were later classified into 11 separate geographic domains displaying similar tectonic characteristics. Moreover, available paleomagnetic data in the literature were parametrically resampled, analysed and combined with our data. In the region, there is a positive correlation between rotation amounts and sample ages supporting continuous deformation throughout the Neogene period. The spatial variations of results indicated that the study area can be divided into three main domains based on vertical axis rotations. From the south to the north these domains include SW Anatolian domain with similar to 20 degrees counter-clockwise rotation, Burdur-Dinar-Ulubey domain with similar to 4 degrees counter-clockwise rotation and northern areas characterized by clockwise rotations. The identified domains of counter-clockwise rotation are separated by a well-defined NW-SE striking Acipayam Transfer Zone and there is no differential rotation in agreement with the presence of NE-SW striking shear zone in the region. Therefore, we concluded that the Pliny-Strabo STEP Fault have not propagated into the over-riding plate as a shear zone. This implies that there is no evidence to support the presence of alleged Fethiye-Burdur Fault Zone as suggested, and its existence is dubious. (C) 2018 Elsevier B.V. All rights reserved.
Paleomanyetik (Manyetostratigrafi) Yöntemler ile Van Bölgesi En Genç Denizel Biriminin (Van Formasyonu) Yüksek Çözünürlükte Yaşlandırılması: Arap-anadolu Plakaları Arası Gerçekleşen Kıtasal Çarpışmanın Zamanlaması Hakkında Çıkarımlar
(2019) Gulyuz, Erhan; Yeşilova, Çetin; Özkaptan, Murat
Avrasya ? Arap plakaları arasındaki yakınsama Neotetis Okyanusunun dereceli olarak kapanmasına ve Hint Okyanusu ile Akdeniz arasındaki açık deniz baglantısının erkan Miyosende kesilmesine neden olmustur. Neotetis havzalarının kalıntıları Dogu Anadolu?da dagılmıs halde bulunmaktadır. Van bölgesi bu kalıntı havzalardan birine dogal olarak ilgili deniz koridorunu son derece iyi temsil eden bir stratigrafik sekansa sahiptir (Van formasyonu). Bu formasyon deniz deniz, karasal ve sıgı deniz çökelleri arasındaki geçisleri temsil eden üç üye ile temsil edilir. Bu formasyon Neotetisin geç dönem kapanımının aydınlatılması anlamında ahantar bir seviye olarak düsünülmüstür çünkü bu formasyon Dogu Anadoludaki en genç denizel birimlerden biridir. Proje kapsamında Van bölgesindeki deniz-ara geçisini yaslandırmak ve bölgedeki deformasyon davranıslarını daha iyi belirlemek için yeni manyetostratigrafik ve manyetik duyarlılık anizotropisi (AMS) verileri sunulmustur. Van formasyonu statigrafik sırada yüksek çözünürlükte ~350 yönlü paleomanyetik sondajla örneklenmistir. Bu örnekler termal (TH) ve alternative alan (AF) demanyetizasyonuna maruz bırakılıp örneklerdeki manyetik polariteler belirlenmistir. Elde edilen manyetik polariteler Jeomanyetik Polarite Zaman Abagıyla (GPTS) ile korele edilerek birimin tabanının ~19.5 My?da, birimdeki denizel-karasal ortam geçisinin 18.8 My?da ve birimin gözlemlenen tavanının ~16.8 My?da çökeldigi belirlenmistir. AMS verilerinin sundugu genislemeli-sıkısmalı rejim geçisinin yası ise ~19 My olarak belirlenmistir. Bu yas bölgedelki derin denizel ortamının sonlanmasıyla neredeyse aynı zamana denk gelmektedir. Proje kapsamında iddia edilen bölgede derin denizel çökelimin bitmesinin ve stress rejiminin ani degisiminin bölgede meydana geldigi düsünülen Avrasya-Arap plakaları arasındaki çarpısmanın baslangıcını ve Neotetis okyanusal kabugunun tamamen tükenmesini zamansal anlamda sınırlayacagıdır
Relationship Between the Anisotropy of Magnetic Susceptibility and Development of the Haymana Anticline, Central Anatolia (Turkey)
(Tubitak Scientific & Technological Research Council Turkey, 2019) Ozkaptan, Murat; Gulyuz, Erhan
Integrated structural and anisotropy of magnetic susceptibility (AMS) analyses were carried out on the Campanian-Maastrichtian shale-mudstone dominated sedimentary sequences (Haymana Formation) cropping out within the doubly plunging Haymana Anticline in Central Anatolia (Turkey). In order to understand the relationship between the development of magnetofabrics and the tectonic processes, six sites from different parts of the anticline were sampled and analyzed. AMS lineations from 634 cylindrical samples and structural data were collected in the field. The results show very high correlation with the structural trend of the region and indicate that the maximum susceptibility vector (k(1)) is almost parallel to the Haymana Anticline fold axis (similar to E-W) and the trace of the Derekoy Thrust Fault, which is the basin-bounding fault at the northern margin of the Haymana Basin. In order to assess the relationship between shortening ratios and obtained AMS vectors, a number of balanced cross-sections are constructed along five traverses almost perpendicular to the axis of the anticline. Results from both the AMS and the balanced cross-sections yielded similar shortening ratios (similar to 18%-32%) that decrease towards the eastern closure of the anticline from its culmination. In a regional sense, we related these results to compressional/transpressional deformation that formed during the Eocene to Early Miocene period. Differential shortening ratios calculated from AMS and restored balanced cross-sections indicate that the shortening is associated with the transcurrent tectonics, possibly in relation with rotational convergence of the Pontides and the Taurides and/or the oblique indentation of the Kirsehir Block into the Pontides during or subsequent to the collision.
Repeated Reactivation of Clogged Permeable Pathways in Epithermal Gold Deposits: Kestanelik Epithermal Vein System, Nw Turkey
(Geological Soc Publ House, 2018) Gulyuz, Nilay; Shipton, Zoe K.; Kuscu, Ilkay; Lord, Richard A.; Kaymakci, Nuretdin; Gulyuz, Erhan; Gladwell, David R.
This study presents a detailed study of the dimensions, geometry, textures and breccias of a well-exposed epithermal vein system, the Kestanelik gold deposit in the Biga Peninsula, NW Turkey, and investigates the permeability enhancement mechanisms in epithermal gold deposits. Here mineralization is associated with quartz veins up to 13.6 m thick. Vein textures and breccia components indicate repeated sealing and subsequent brecciation of wall rock and pre-existing vein infill. Field and petrographic analyses characterize east-west-trending veins as left lateral faults, whereas NE-SW-trending veins are extensional (Mode I) fractures. Cataclasite and tectonic breccia of wall rocks and early quartz, hydrothermal crackle breccias, and matrix-supported chaotic breccias of pre-existing vein infill, all of which are cemented by late iron-oxide-bearing quartz, indicate that co-seismic rupturing and hydraulic fracturing are two major permeability enhancement mechanisms. In addition, transient variations in local stress direction, caused by syn-mineralization dyke intrusion, may have enhanced permeability on misoriented surfaces and at locations where the dip changes. This study emphasizes the importance of understanding structural geology and kinematics as controls on the location of boiling and mineralization mechanisms in epithermal gold deposits.