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Northern Anatolia has been the subject of many studies due to its complex tectonic structure. Here we report on a paleomagnetic study sampled from upper Cretaceous to middle Miocene sedimentary and volcanic rocks at 54 sites running along the traces of the North Anatolian Fault in the Pontides, Northern Türkiye, to define the post-late Cretaceous tectonic evolution of the area. The results were evaluated together with previously published paleomagnetic data around the Kırşehir Block and the Pontides. The rotational pattern showed distinct phases in the Pontides after the late Cretaceous. A predominant late Cretaceous-middle Eocene clockwise rotation up to 38.1° ± 17.4° probably occurred due to the progressive collision between the Pontides and the Kırşehir Block from west to east. The ongoing deformation continued along the İzmir-Ankara-Erzincan Suture Belt during the middle Eocene-middle Miocene time as evidenced by the paleomagnetic rotation pattern, while no significant rotations were observed further north of the suture zone at this time period. On the other hand, middle Miocene paleomagnetic sites showed a counterclockwise rotation, reflecting the westward escape of the Anatolian microplate, while local fault-bounded vertical block rotations were apparent in places. [ABSTRACT FROM AUTHOR]

The Eastern Pontides are the northeasternmost component of the Anatolian orogen. Its geological development is closely associated with the evolution of the Ankara-Erzincan Suture. It exhibits records of the events from the opening to the elimination of the surrounding oceans. During the Late Palaeozoic, the Pontides were located in north of Gondwana, facing the Palaeo-Tethys Ocean. The southward subduction of the Palaeo Tethyan oceanic lithosphere generated an active continental margin and opening of the Neo-Tethys Ocean as a back-arc basin during the Early Mesozoic. Throughout the Jurassic-Early Cretaceous, the Pontides remained a passive continental margin facing the Neo-Tethys in the south. Arc reversal occurred as the Neo-Tethys began subducting under the Pontides during the late Early Cretaceous (?)-Late Cretaceous. The Pontides experienced four collisional events throughout the development of the Ankara-Erzincan Suture; (1)- a forearc-arc collision occurred when the accretionary complex, which formed along the southern edge of the Pontides was backthrust over its leading edge during the Late Campanian. (2)- This was followed by a continent-arc collision when the Kırşehir Massif and the underlying NeoTethyan ophiolite nappe collided with and thrust over the Pontides at the end of the Early Eocene. (3)- Following the oceanic lithosphere's total demise, the remnant basin survived above the remaining part of the accretionary complex located between the Pontides, and the Taurus was closed under the northerly advancing Taurus nappes during the Late Eocene. The latest collision (4) is the collision of the Arabian Plate with the Anatolian plates. The Arabian Plate's continuing northward advance after the demise of the NeoTethyan Ocean squeezed and shortened Eastern Anatolia. From this time onward, the Eastern Pontides were thrust to the north and the south over the surrounding tectonic belts and started to rise as a coherent block. [ABSTRACT FROM AUTHOR]

During the Late Cretaceous, a magmatic arc extended from the Lesser Caucasus through the northern margin of the Pontides into Srednogorie, Timok, Banat, and Apuseni (ABTS) in the Balkans for a distance of 2700 km. We studied the arc volcanic rocks in three regions in the Western Pontides and reviewed the geological data on the Lesser Caucasus-Pontide-ABTS magmatic arc, which shows several common features. Prior to the start of the arc magmatism, the region underwent uplift and erosion. New and published geochronologic and biostratigraphic data show that magmatism in the Lesser Caucasus-Pontide-ABTS arc started in the Turonian (ca. 93 Ma) peaked in the middle Campanian (80–78 Ma) and became rare and sporadic after the late Campanian (ca. 75 Ma). Magmatism was dominantly calc-alkaline to high-K calc-alkaline and shows typical subduction geochemical signatures. Late Cretaceous volcanism took place in a submarine and extensional environment. In the Lesser Caucasus-Pontide-ABTS belt, the arc volcanic rocks are overlain by Maastrichtian to Palaeocene marine limestones and sandstones, marking the end of the main phase of arc magmatism. However, in the Kefken region in the Western Pontides, Maastrichtian limestone sequence includes a volcanic horizon with a U-Pb zircon age of ca. 71 Ma. The Maastrichtian volcanic rocks show a more varied geochemistry than the older arc volcanic rocks, and include alkaline basalts, calc-alkaline basalts, and adakites. The coeval start of arc magmatism in the 2700-km-long Lesser Caucasus-Pontide-ABTS belt is related to the inception of the Africa-Eurasia convergence at ca. 96 Ma, which is also independently indicated by the beginning of intra-oceanic subduction, inferred from the ages of sub-ophiolite metamorphic rocks in Anatolia. The end of magmatism is linked to a marked decrease in the convergence rate during the Campanian, which was also partitioned between the northern and southern Tethyan subduction zones. [ABSTRACT FROM AUTHOR]

Several models exist concerning the deformation history of the Pontides in North Anatolia during the Cretaceous period, which vary depending on the positions of the Istanbul and Sakarya zones, the consumption of the northern branches of the Neotethys ocean and the rifting of several sub-basins. Notably, the early Cretaceous tectonic history of the Pontides involved the closure of the northern Neotethys ocean (Intra-Pontide ocean), and the collision between the Istanbul and Sakarya zones, producing thrust structures along the collisional front. The lack of palaeomagnetic data providing evidence for this deformation pattern demonstrates that further investigation is required, particularly focusing on the Lower Cretaceous strata in the Pontides. Thus, this study aimed to examine samples from a total of 78 sites from the Lower–Upper Cretaceous sedimentary rocks, and Middle Eocene to Middle Miocene sedimentary and volcanic rocks. Results of this study indicated large counterclockwise rotations up to R ±Δ R = −73.9°±9.1°, and small clockwise rotations of R ±Δ R  = 14.2°±12.2° in the Istanbul and Sakarya zones, during the Early Cretaceous and Late Cretaceous periods. These rotation patterns are accompanied by the closure of the Intra-Pontide ocean, and the collision between the Istanbul and Sakarya zones during the Early and Late Cretaceous periods. On the other hand, in the Middle Eocene, small counterclockwise rotations of R ±Δ R = −6.4°±13.9° and 4.6°±12.9° along the western coastline of the Pontides indicated that the northern margin of the Pontides was stable during this period. [ABSTRACT FROM AUTHOR]

We report detrital zircon ages from the Upper Cretaceous (Campanian–Maastrichtian) turbiditic sandstones from the Pontides and the Anatolide–Tauride Block, which were located on opposite margins of the Tethys ocean during most of the Paleozoic and Mesozoic. The large data set includes both published and new detrital zircon ages from the Upper Cretaceous Pontide sandstones (2730 zircon ages from 26 samples) and new detrital zircon ages from the uppermost Cretaceous Bornova Flysch of the Anatolide–Tauride Block (378 ages from five samples). Phanerozoic detrital zircons from the Upper Cretaceous sandstones of the Pontides are predominantly Late Cretaceous (56%) followed by Carboniferous (7.9%), Devonian (5.3%), Jurassic (3.1%) and Triassic (2.9%). In contrast, there are no Cretaceous and Jurassic detrital zircons in the uppermost Cretaceous Bornova Flysch, and the Phanerozoic detrital zircon populations are mainly Carboniferous (41.3%), Triassic (7.1%), Permian (6.9%) and Devonian (5.3%). The absence of Cretaceous and Jurassic zircons in the Bornova Flysch shows that there was no sediment transport between the Pontides and the Anatolide–Tauride Block during the latest Cretaceous (75–70 Ma); it also shows that the latest Cretaceous – Paleocene deformation of the Bornova Flysch Zone predates the collision between the Pontides and the Anatolide–Tauride Block, and is associated with ophiolite obduction. The dominance of Carboniferous detrital zircons in the Bornova Flysch Zone underlines that Carboniferous magmatic activity in the Anatolide–Tauride Block, and hence on the northern margin of Gondwana, was more significant than hitherto recognized. [ABSTRACT FROM AUTHOR]

A new genus and species of omomyid primate is described from the middle Eocene (Lutetian) Lülük Member of the Uzunçarşidere Formation, Orhaniye Basin, north-central Anatolia, Turkey. This is the first Eocene primate to be reported from the vast area between Switzerland and Pakistan. The new taxon is currently represented by a single dentary fragment, limiting the scope of morphological comparisons that can be made with related taxa. Nevertheless, its dentition differs fundamentally from that of contemporary European microchoerids. The new taxon most closely resembles North American middle Eocene omomyines such as Mytonius hopsoni , and it is therefore interpreted as a member of the Asian/North American omomyine radiation. Its occurrence on the Pontide microcontinent must have resulted from sweepstakes dispersal across the intervening Tethyan barrier that separated the Pontides from adjacent parts of Eurasia during the Lutetian. Sweepstakes dispersal by various terrestrial mammal clades, especially rodents and primates, was facilitated by Eocene greenhouse climatic conditions, which promoted extreme precipitation events and frequent flooding of major river drainages. [ABSTRACT FROM AUTHOR]

U–Pb dating, Hf-isotope, and trace-element studies on two detrital zircon samples from sandstone interlayers in the Upper Jurassic conglomerates of the Southern coast of the Mountainous Crimea provide new information on the primary crystalline complexes from which those conglomerates were sourced. The U–Pb age spectra of studied zircons suggest that they were most likely sourced from the (meta)sedimentary complexes of the Eastern and Western Pontides blocks and the Dobrogea platform. In particular, a close similarity of the Precambrian age spectra with the detrital zircons from Late Neoproterozoic–Late Paleozoic (meta)sedimentary complexes of the Dobrogea block provides strong supporting evidence for the affinity between the Pre-Mesozoic basement of the Crimea and the Dobrogea platform. The zircons in the first sample were recycled through Dobrogea sedimentary complexes and originated from terranes with Amazonia affinities, while zircons in the second sample were recycled through the Taurides and originated from terranes related to northeastern Africa and Arabia. The strong similarity of the Precambrian parts of the age spectra of the Dobrogea complexes and the sample K15-007 suggests a resemblance of the Crimea's Pre-Mesozoic foundation and the Dobrogea platform. Initial analytical data are provided in Electronic Supplementary Materials A (ESM A). Descriptions of measurement parameters, methodologies, and constants used to process primary analytical data and some processing results are reported in ESM B (Figs. B1–B8). Schemes of locations within Balkans–Anatolia–Black Sea–Caucasus region the crystalline complexes with Jurassic, Triassic, Permian–Carboniferous, as well as Late Neoproterozoic–Cambrian and Ordovician–Devonian ages are in ESM C (Figs. C1, C3–C5). [ABSTRACT FROM AUTHOR]

The Hazinemağara (Gümüşhane) Pb-Zn deposit is located in the southern part of the Eastern Pontides Orogenic Belt in northeastern Turkey. It occurs as irregularly shaped ore bodies with breccia fill structure within the intraformational breccia or brecciated horizons of limestone in the Upper Jurassic-Lower Cretaceous Berdiga Formation. The dominant ore minerals are pyrite, sphalerite, galena, and tetrahedrite, and the major gangue minerals are calcite, quartz, and barite. Microthermometric investigations of the fluid inclusions show that the ore-forming fluids contain CaCl2 and MgCl2 in addition to NaCl. The salinity of the fluid ranges from 1.7% to 9.2% with an average of 5.7% (wt.% NaCl equivalent) (n = 93). The homogenization temperature of the fluid ranges from 160.0 to 386.0 °C with an average of 263.5 °C (n = 98). The plots of the dD values of water trapped in fluid inclusions hosted by barite and quartz (in the range of 92 to 81) and the d18O values calculated for water in equilibrium with these minerals (4.1 to 18.5) are closer to the magmatic range than any other water sources and suggest the presence of magmatic water in hydrothermal fluid with some modifications by interaction with fluid from surrounding sedimentary rocks. The sulfur isotope composition of sulfide minerals (in the range of -7.8VCDT to +5.4VCDT, avg.: -2.0; n = 13) indicates a magmatic source for sulfur. It is concluded that the magmatic water derived from deep-seated Eocene plutonic rocks (Kaçkar Granitoids-I and -II) possibly carried metals and the sulfur derived from the source magma or leached from magmatic rocks on the pathway along the fault zones and precipitated mainly within voids between limestone fragments in intraformational breccia horizons of the Berdiga Formation. The Berdiga Formation is observed in large areas within the Eastern Pontide region and the intraformational breccia horizons could provide large stratabound ore potential. [ABSTRACT FROM AUTHOR]

The newly recognized Upper Cretaceous (~87 Ma) olistostrome belt in central Turkey west of Ankara extends for more than 112 km subparallel to the Izmir‐Ankara suture with a width of 10 km. The Alacaatlı Olistostromes are stratigraphically underlain by a Triassic basement, and are up to 2 km thick. Over 80% of the blocks in the olistostromes consist of pelagic limestones, which reach up to 300 m in size; other blocks include basalt, chert, serpentinite, tuff, and sandstone. The limestone blocks are Jurassic and Cretaceous in age with micropaleontology documenting the presence of Callovian‐Oxfordian, Tithonian, Berriasian, Aptian, Albian, Cenomanian, and Turonian stages. The flows are separated by intrabasinal sediments of shale, siltstone, and volcaniclastic sandstone with Albian (108–101 Ma) detrital zircons. The olistostromes show minor tectonic deformation, and are unconformably overlain by Santonian pelagic limestones. The deposition of the Alacaatlı Olistostromes was followed by arc magmatism, which started in the Campanian (~78 Ma) after a period of shortening and uplift, and the region became a fore‐arc basin with deposition of shale and volcaniclastic sandstone with Campanian (78–72 Ma) detrital zircons. A number of peculiar features of these olistostromes including rapid uplift and erosion before the creation of a deep, short‐lived (89–86 Ma) ephemeral basin, dominance of deep marine limestone blocks, and inception of arc magmatism approximately 9 Myr after their deposition indicate a major tectonic event involving the disruption of the continental margin prior to the onset of arc magmatism. This event is interpreted as a change from transform margin to subduction. Key Points: A belt of Upper Cretaceous (approximately 87 Ma) olistostromes, >112 km‐long and 2 km in stratigraphic thickness, crops out in central TurkeyThe olistostromes contain Jurassic and Cretaceous pelagic limestone and ophiolite blocks and rest stratigraphically on a Triassic basementDisruption of the continental margin during a change from transform to subduction was responsible for the formation of the mass flows [ABSTRACT FROM AUTHOR]

Amasya dolaylarında Geç Kretase yaşlı birimler arasında Pontid yayönü havza çökelleri ve buna eşlik eden volkanik kayalar ile temsil edilen volkanoklastik bir istif yer alır. Bu birim içerisindeki volkanik kayalar, Pontid kuşağı aktif kıta kenarı volkanik kuşağının ürünleri olan kalkalkalin kayalar ve bunlara eşlik eden alkalin-potasik/ultrapotasik kayalardan olu- şur. Bu çalışmada, benzer jeokimyasal özellikler sergileyen alkali nitelikli kayalar arasın- da meydana gelmiş olan farklılaşma süreçleri petrolojik modeller bazında ele alınmaktadır. Petrografik olarak lösitit, minet ve trakit olarak tanımlanan alkali ultrapotasik kayalar vol- kanoklastik istif içerisinde stok, dayk ve lav akıntıları şeklinde gözlenirler. Çarpışmalı tek- tonizmanın kontrolüyle gelişen orojenik kuşaklarda gözlenen ultrapotasik ve yüksek potas- yumlu kayaların farklılaşmasında düşük basınç kristallenme süreçlerine eşlik eden asimi- lasyon ve kabuk kirlenmesi (AFC) olayları etkindir. Amasya yöresi Geç Kretase ultrapota- sik magmatizmasının en genç volkanik ürünleri trakitik kayalarla temsil edilir ve bunlar jeokimyasal özellikleri bakımından ultrapotasik kayaların en evrimleşmiş olanlarıdır. Bu- radan hareketle, volkanoklastik istif içerisindeki en ilksel örnek başlangıç bileşimi, Orta Pontidler’in Triyas yaşlı metapelitik kayaları da kirletici kabul edilerek, kristallenmeye eş- lik eden kabuk katkısı süreçlerinin (AFC) ultrapotasik ergiyiklerden lösitit, minet ve traki- tik litolojilerin farklılaşmasında etkin olup olmadığı belirlenmeye çalışılmıştır. AFC mo- delleme sonuçları trakitik kayaların ilksel ultrapotasik ergiyiklerin kristallenmeleri sürecin- de, en fazla % 5 civarında Orta Pontid temel kayalarına ait birimleri özümsemesiyle oluş- tuğunu ortaya koymuştur. Bununla birlikte lösitit ve minet farklılaşması fraksiyonel kris- tallenme ya da eşlik eden kabuk kirlenmesi süreçleri ile mümkün görünmemektedir.

Abstract We analysed the interplay between coastal uplift, sea level change in the Black Sea, and incision of the Kızılırmak River in northern Turkey. These processes have created multiple co-genetic fluvial and marine terrace sequences that serve as excellent strain markers to assess the ongoing evolution of the Pontide orogenic wedge and the growth of the northern margin of the Central Anatolian Plateau. We used high-resolution topographic data, OSL ages, and published information on past sea levels to analyse the spatiotemporal evolution of these terraces; we derived a regional uplift model for the northward-advancing orogenic wedge that supports the notion of laterally variable uplift rates along the flanks of the Pontides. The best-fit uplift model defines a constant long-term uplift rate of 0.28 ± 0.07 m/ka for the last 545 ka. This model explains the evolution of the terrace sequence in light of active tectonic processes and superposed cycles of climate-controlled sea-level change. Our new data reveal regional uplift characteristics that are comparable to the inner sectors of the Central Pontides; accordingly, the rate of uplift diminishes with increasing distance from the main strand of the restraining bend of the North Anatolian Fault Zone (NAFZ). This spatial relationship between the regional impact of the restraining bend of the NAFZ and uplift of the Pontide wedge thus suggests a strong link between the activity of the NAFZ, deformation and uplift in the Pontide orogenic wedge, and the sustained lateral growth of the Central Anatolian Plateau flank. Highlights • Multiple fluvial, deltaic and coastal terraces along the Black Sea coast of Turkey. • New terrace chronology that spans the last 545 ka (MIS 14). • The uplift of the Central Pontides sustained at a rate of 0.28 ± 0.07 m/ka. • A northward-growing orogenic wedge that spatially coincides with a restraining bend. • The lateral growth of the northern flanks of the Central Anatolian Plateau. [ABSTRACT FROM AUTHOR]

Abstract During Late Jurassic–Early Cretaceous the Pontides were the site of a wide carbonate platform facing the Tethys ocean in the south. In the western Pontides the Upper Jurassic–Lower Cretaceous shallow marine carbonates abut the Tethyan İzmir-Ankara suture with no evidence for platform margin deposits. The Sivrihisar klippe 50 km south of the İzmir-Ankara suture preserves a record of the missing platform margin. In the Upper Jurassic–Lower Cretaceous carbonates exposed in this Sivrihisar klippe, two coeval but dissimilar rock packages, separated by a thrust fault, have been detected. The lower succession is composed of Kimmeridgian–Valanginian slope to basin deposits. Within these carbonates the following biozones are defined: Globuligerina oxfordiana – Mohlerina basiliensis Zone (Kimmeridgian), Saccocoma Zone (lower Tithonian), Protopeneroplis ultragranulata Zone (upper Tithonian), Crassicollaria Zone (massutiana Subzone – uppermost Tithonian), Calpionella Zone (alpina , Remaniella , elliptica Subzones – lower Berriasian), Calpionellopsis Zone (simplex , oblonga Subzones – upper Berriasian) and Calpionellites Zone (darderi Subzone – lower Valanginian). These slope to basin deposits are overthrust from north to south by Kimmeridgian shallow marine carbonates. Within this unit Labyrinthina mirabilis – Protopeneroplis striata Zone (Kimmeridgian) is recognized. Based on the distribution of microfacies types and fossil assemblages, a Kimmeridgian–Valanginian depositional model is proposed for the western Sakarya Zone Carbonate Platform (SCP). The position of the studied sections with respect to the SCP, biofacies and microfacies associations suggest that the studied basin and slope deposits represent the remnants of the southern margin and slope of this carbonate platform largely truncated by erosion. The slope and basinal carbonates overthrusted by the coeval shallow marine deposits in a region situated to the south of the main İzmir-Ankara suture indicates an important imbrication and shortening related to the closure of the Tethys ocean. [ABSTRACT FROM AUTHOR]

Upper Jurassic-lowermost Cretaceous carbonate build-ups are imaged on seismic data in the Black Sea. They form important, untested, hydrocarbon reservoirs that are the focus of active exploration. Outcrop analogues to these build-ups around the Black Sea contain a series of subaerial exposure surfaces. The hiatuses associated with a number of these subaerial exposure surfaces have been dated in a well exposed Callovian or Upper Oxfordian to Barremian shallow-water inner platform carbonate succession (the Berdiga Formation) in the Eastern Pontides using strontium isotope stratigraphy and foraminiferal biostratigraphy. They span the latest Kimmeridgian to Tithonian or Berriasian, and the Hauterivian to Barremian. Less well constrained, but broadly contemporaneous stratigraphic gaps in multiple successions around the Black Sea provide additional insights and point to a regional driving mechanism. The timing of hiatus formation does not correspond to periods of eustatic lowstand. It does coincide, however, with Late Tithonian to Berriasian and Hauterivian to Early Aptian episodes of rifting in the Greater Caucasus Basin, located farther to the north. Thus, it is possible that subaerial exposure was caused by rift flank uplift during periods of regional extension. Uplift due to slab break off is discounted as a control because it post-dates (rather than pre-dates) locally developed Kimmeridgian magmatism. Rift-flank uplift is likely to have also affected carbonate build-ups on the intervening rift shoulders of the eastern Black Sea, the Shatskiy Ridge and the Mid Black Sea High. At outcrop, subaerial exposure is often associated with karstification and secondary porosity development. Similar processes may have occurred in the offshore helping to enhance the reservoir quality of these exploration targets. [ABSTRACT FROM AUTHOR]

The Karadere area to the east of Safranbolu in NW Anatolia is one of the very few localities in Turkey where the contact between the Cadomian basement and the Lower Palaeozoic transgressive succession is well exposed. The Ordovician graptolite Rhabdinopora flabelliformis (Eichwald) ssp. was found in the basal part of the Bakacak Formation, indicating an Early to early Late Tremadocian age for the beginning of the Palaeozoic transgression in the Zonguldak terrane. A few metres above this occurrence, another horizon contains Paradelograptus cf. antiquus (T. S. Hall), which mainly ranges into the Late Tremadocian. Higher up in the Ordovician succession, a new graptolite bed confirms an early Darriwilian (Dw1) age for the middle part of the Karadere Formation with the occurrence of the biozonal index Levisograptus austrodentatus (Harris & Keble) and the first record of Tetragraptus cor (Strandmark) in the area. The palaeobiogeographic distribution of these Karadere fossils is in agreement with a peri-Gondwanan affinity of the Zonguldak Terrane of the Pontides, NW Anatolia, during the Early–Middle Ordovician.

A paleomagnetic study of Cretaceous arc type rocks in the Central-Eastern Pontides and in the Southeastern Taurides investigates the tectonic and paleolatitudinal evolution of three volcanic belts in Anatolia, namely the Northern and Southern Volcanic Belts in the Pontides and the SE Taurides volcanic belt. The paleomagnetic data indicate that magnetizations were acquired prior to folding at most sampling localities/sites, except for those in the Erzincan area in the Eastern Pontides. The Southern Volcanic Belt was magnetized at a paleolatitude between $$23.8_{-3.8}^{+4.2}$$ °N and $$20.2_{-1.2}^{+1.3}$$ °N. Hisarlı (J Geodyn 52:114-128, 2011) reported a more northerly paleolatitude ( $$26.6_{-4.6}^{+5.1}$$ °N) for the Northern Volcanic Belt. The comparison of the new paleomagnetic results with previous ones in Anatolia allows to conclude that the Southern Volcanic Belt in the Central-Eastern Pontides was emplaced after the Northern Volcanic Belt as a result of slab-roll back of the Northern Neotethys ocean in the Late Cretaceous. In the Southeast Taurides, Upper Cretaceous arc-related sandstones were at a paleolatitude of $$16.8_{-3.8}^{+4.2}~$$ . The Late Cretaceous paleomagnetic rotations in the Central Pontides exhibit a counterclockwise rotation of $$R\pm \Delta R=-37.1{}^\circ \pm 5.8{}^\circ$$ (Group 1; Çankırı, Yaylaçayı Formation) while Maastrichtian arc type rocks in the Yozgat area (Group 2) show clockwise rotations R + Δ R = 33.7° ± 8.4° and R + Δ R = 29.3° ± 6.0°. In the SE Taurides counterclockwise and clockwise rotations of $$R\pm \Delta R=-48.6\text{ }\!\!{}^\circ\!\!\text{ }\pm 5.2\text{ }\!\!{}^\circ\!\!\text{ }$$ and $$R\pm \Delta R=+34.1\text{ }\!\!{}^\circ\!\!\text{ }\pm 15.1\text{ }\!\!{}^\circ\!\!\text{ }$$ are obtained (Group 4; Elazığ Magmatic Complex). The Late Cretaceous paleomagnetic rotations in the Pontides follow a general trend in concordance with the shape of the suture zone after the collision between the Pontides and the Kırşehir block. The affect of the westwards excursion of the Anatolian plate and the associated fault bounded block rotations in Miocene are observed in the east of the study area and the SE Taurides. [ABSTRACT FROM AUTHOR]

Two Gondwana-derived Paleozoic belts rim the Archean/Paleoproterozoic nucleus of the East European Platform in the Black Sea region. In the north is a belt of Paleozoic passive-margin-type sedimentary rocks, which extends from Moesia to the Istanbul Zone and to parts of the Scythian Platform (the MOIS Block). This belt constituted the south-facing continental margin of the Laurussia during the Late Paleozoic. This margin was deformed during the Carboniferous by folding and thrusting and forms the Variscan foreland. In the south is a belt of metamorphic and granitic rocks, which extends from the Balkanides through Strandja, Sakarya to the Caucasus (BASSAC Block). The protoliths of the metamorphic rocks are predominantly late Neoproterozoic granites and Paleozoic sedimentary and igneous rocks, which were deformed and metamorphosed during the Early Carboniferous. There are also minor eclogites and serpentinites, mostly confined to the northern margin of the BASSAC Block. Typical metamorphism is of low pressure-high temperature type and occurred during the Early Carboniferous (Visean, 340-330 Ma) coevally with that observed in the Central Europe. Volumetrically, more than half of the crystalline belt is made up of Carboniferous-earliest Permian (335-294 Ma) granites. The type of metamorphism, its concurrent nature over 1800 km length of the BASSAC Block and voluminous acidic magmatism suggest that the thermal event probably occurred in the deep levels of a continental magmatic arc. The BASSAC arc collided with Laurussia in the mid-Carboniferous leading to the foreland deformation. The ensuing uplift in the Permian resulted in the deposition of continental red beds, which are associated with acidic magmatic rocks observed over the foreland as well as over the BASSAC Block. In the Black Sea region, there was no terminal collision of Laurussia with Gondwana during the Late Paleozoic and the Laurussia margin continued to face the Paleo-Tethyan ocean in the south. [ABSTRACT FROM AUTHOR]

Doğu Karadeniz Bölgesi volkanojenik masif sülfid (VMS) yataklarının cevherleri yapı-doku, bileşen ve konum olarak incelendiğinde “cevher fasiyesleri” ve “cevherli sedimanter fasiyesler” olarak sınıflandırılabilir. Cevher fasiyesleri hidrotermal-metasomatik, deniz tabanı hidrotermal ve biyolojik fasiyeslerden oluşur. Hidrotermal-metasomatik fasiyesler deniz tabanının altındaki (sub-sea floor) ornatma süreçlerini kapsar ve ağsal-saçınımlı, masif damar ve masif merceklerle temsil edilir. Deniz tabanının hemen altındaki volkano-sedimanter kayaçlar içerisinde oluşmuş kırık ve çatlaklar içerisinde sülfit minerallerinin yığışımı ile oluşur ve bazı yatakların önemli bileşenleridir. Deniz tabanı hidrotermal fasiyesler deniz tabanındaki sülfit yığışımlarıdır ve hidrotermal çıkış bacaları ile kırıntılı sülfit cevherlerle karakterizedir. Kırıntılı sülfit cevherler yakın (proximal) ve uzak (distal) fasiyeslerine ayrılır. Cevherli sedimanter fasiyesler, cevherli seviyenin hemen üzerinde oluşmuş fazla kalın olmayan yanal uzanımlı demirli çörtler (exhalite?) ile ayırt edilir. Biyolojik fasiyesler ise deniz tabanı yığışımı için karakteristik olan çıkış kanalı (vent) fosil faunası ile temsil edilir.Doğu Karadeniz Bölgesi masif sülfid yataklarının cevherleri yapı-doku ve bileşenler açısından iyi korunmuş özelliklere sahiptir. Bu iyi korunmuş özelliklerden yola çıkarak bazı masif sülfid yatakların deniz tabanında (sea floor) moloz/kütle akmaları şeklinde, bazı yatakların ise deniz tabanının hemen altındaki ornatma süreçleriyle oluştuğu söylenebilir. Cevherin kırıntılı (klastik) doğası ve bazı sinsedimanter yapılar bu yatakların oldukça hareketli bir ortamda çökelmiş olduklarına işaret eder. Doğu Karadeniz Bölgesi VMS yataklarında gözlenen kırıntılı sülfit cevher, sülfit çıkış bacaları, demirli çörtler ve fosil fauna varlığı deniz tabanında çökelime işaret eden önemli verilerin başında gelir. Cevher fasiyeslerinin belirlenmesi VMS yataklarının bölgesel ve küresel ölçekte sınıflandırılması için belirleyici bir yöntemdir

The Haymana region in Central Anatolia is located in the southern part of the Pontides close to the İzmir-Ankara suture. During the Cretaceous, the region formed part of the south-facing active margin of the Eurasia. The area preserves a nearly complete record of the Cretaceous system. Shallow marine carbonates of earliest Cretaceous age are overlain by a 700-m-thick Cretaceous sequence, dominated by deep marine limestones. Three unconformity-bounded pelagic carbonate sequences of Berriasian, Albian-Cenomanian and Turonian-Santonian ages are recognized: Each depositional sequence is preceded by a period of tilting and submarine erosion during the Berriasian, early Albian and late Cenomanian, which corresponds to phases of local extension in the active continental margin. Carbonate breccias mark the base of the sequences and each carbonate sequence steps down on older units. The deep marine carbonate deposition ended in the late Santonian followed by tilting, erosion and folding during the Campanian. Deposition of thick siliciclastic turbidites started in the late Campanian and continued into the Tertiary. Unlike most forearc basins, the Haymana region was a site of deep marine carbonate deposition until the Campanian. This was because the Pontide arc was extensional and the volcanic detritus was trapped in the intra-arc basins and did not reach the forearc or the trench. The extensional nature of the arc is also shown by the opening of the Black Sea as a backarc basin in the Turonian-Santonian. The carbonate sedimentation in an active margin is characterized by synsedimentary vertical displacements, which results in submarine erosion, carbonate breccias and in the lateral discontinuity of the sequences, and differs from blanket like carbonate deposition in the passive margins. [ABSTRACT FROM AUTHOR]

The Hallstatt-type limestones in the Central Pontides yield abundant conodonts of the genus Gladigondolella ranging throughout the entire studied sequence and indicating Anisian to Early Carnian ages. Gladigondolella okayi n. sp. is described. [ABSTRACT FROM AUTHOR]

Upper Cretaceous volcano-sedimentary successions in the Central Pontides of Turkey, related to the closure of the Tethys Ocean, include a variety of alkaline ultrapotassic igneous rocks that have been classified as leucititic, lamprophyric and trachytic based on their mineral paragenesis. Although the ultrapotassic rocks display a range of K2O contents (0.9-8.4 wt %) that may partly reflect alteration processes, they display subduction-related trace element signatures characterized by significant enrichment of large ion lithophile elements and light rare earth elements relative to high field strength elements and heavy rare earth elements and depletion of Nb and Ta. However, their initial Nd-Sr isotope compositions plot within the mantle array. The nature of the mantle source of their parental magmas is inferred to be highly complex, involving contributions from several different components based on contrasting geochemical and isotopic features: (1) a depleted mantle source, which is indicated by unradiogenic 87Sr/86Sri (0.70449-0.70609) and radiogenic 143Nd/144Ndi (0.51252-0.51269); (2) an obvious requirement of mantle phlogopite to explain the high potassium contents; (3) slabderived fluids, which are indicated by ultra-low δ18Ocpx ratios regardless of the ultrapotassic rock type (2.4-5‰), with high Ba/La and Nb/Ta, low Th/La and the most radiogenic 143Nd/144Ndi; (4) a contribution from subducted sediments giving rise to low Ce/Pb ratios and high Th contents; (5) the introduction of convective mantle into the source region with an asthenospheric Pb isotope signature. Whereas the differentiation of silica-undersaturated leucititic and lamprophyric magmas was driven by heteromorphic reactions, owing to the absence of major and trace element variations between the resultant rock types, the formation of silica-saturated trachytic rocks was the result of assimilation- fractional crystallization processes. We propose that a complex sequence of subduction events, starting from at least the Middle Triassic, caused metasomatism of the depleted mantle source and the generation of the Late Cretaceous ultrapotassic parental magmas, facilitated by slab roll-back followed by slab tearing. [ABSTRACT FROM AUTHOR]

Geophysical data allowed the construction of a ~250-km-long lithospheric-scale balanced cross section of the southern Black Sea margin (Espurt et al. in Lithosphere 6:26-34, ). In this paper, we combine structural field data, stratigraphic data, and fault kinematics analyses with the 70-km-long onshore part of the section to reconstruct the geodynamic evolution of the Central Pontide orogen. These data reveal new aspects of the structural evolution of the Pontides since the Early Cretaceous. The Central Pontides is a doubly vergent orogenic wedge that results from the inversion of normal faults. Extensional subsidence occurred with an ENE-trend from Aptian to Paleocene. We infer that the Black Sea back-arc basin also opened during this period, which was also the period of subduction of the Tethys Ocean below the Pontides. As in the Western Pontides, the Cretaceous-Paleocene subsidence was interrupted from Latest Albian to Coniacian time by uplift and erosion that was probably related to a block collision and accretion in the subduction zone. The restoration of the section to its pre-shortening state (Paleocene) shows that fault-related subsidence locally reached 3600 m within the forearc basin. Structural inversion occurred from Early Eocene to Mid-Miocene as a result of collision and indentation of the Pontides by the Kırşehir continental block to the south, with 27.5 km (~28 %) shortening along the section studied. The inversion was characterized by NNE-trending shortening that predated the Late Neogene dextral escape of Anatolia along the North Anatolian Fault and the modern stress field characterized by NW-trending compression within the Eocene Boyabat basin. [ABSTRACT FROM AUTHOR]

A detailed taxonomical study was carried out for the identification of encrusting micro-organisms. Among these microencrusters, Perturbatacrusta leini, Iberopora bodeuri, Calcistella jachenhausenensis, and Pseudorothpletzella schmidi have been taxonomically revealed for the first time in Turkey. Within the biostratigraphic frame of the İnaltı Formation consisting of Mesoendothyra izjumiana zone (Kimmeridgian), Calcistella jachenhausenensis zone (Lower Tithonian-Upper Tithonian) and Protopeneroplis ultragranulata zone (Upper Tithonian-Berriasian), carbonate sedimentation occurred in five depositional environments comprising slope, fore-reef, reef, back-reef and lagoonal environments. The majority of the reefal deposits of the İnaltı carbonates can be classified as coral-microbial-microencruster boundstones, which frequently occur in association with back-reef and fore-reef deposits within the Kimmeridgian-Berriasian interval. A shallowing and a subsequent deepening of water depth in the Berriasian have been revealed by the examination of stacking patterns and vertical evolution of the microfacies. Based on the observed microfacies and general features of micro-encrusting organisms, it is concluded that İnaltı carbonates share many similarities with the reefal carbonate deposits of Intra-Tethyan domain in terms of microfacies types and microencruster content. [ABSTRACT FROM AUTHOR]

Albian-Turonian subduction-accretionary complexes are exposed widely in the Central Pontides. A major portion of the accretionary complexes is made up of a metaflysch sequence consisting of slate/phyllite and metasandstone intercalation with blocks of marble, Na-amphibole bearing metabasite, and serpentinite. The metaflysch sequence represents distal parts of a large Lower Cretaceous submarine turbidite fan deposited on the Laurasian active continental margin that was subsequently accreted and metamorphosed during the Albian. Raman spectra of carbonaceous material of the metapelitic rocks revealed that the metaflysch consists of metamorphic packets with distinct peak metamorphic temperatures. The majority of the metapelites are low-temperature (ca. 330°C) slates characterized by lack of differentiation of the graphite (G) and D2 defect bands. They possibly represent offscraped distal turbidites along the toe of the Albian accretionary wedge. Other phyllites are characterized by a slightly pronounced G band with a D2 defect band occurring on its shoulder. Peak metamorphic temperatures of these phyllites are constrained to 370-385 °C. The phyllites are associated with a strip of incipient blueschist facies metabasites and are found as a sliver within the offscraped distal turbidites. We interpret the phyllites as underplated continental sediments together with oceanic crustal basalt along the basal décollement. Tectonic emplacement of the underplated rocks into the offscraped distal turbidites was possibly achieved by out-of-sequence thrusting causing tectonic thickening and uplift of the wedge. [ABSTRACT FROM AUTHOR]

The basement of the Central Pontides, and by implication that of Crimea, consists of pre-Permian low-grade metaclastic rocks intruded by latest Permian – Early Carboniferous (305–290 Ma) granitoids. Further up in the stratigraphic sequence are Triassic limestones, which are now preserved as olistoliths in the deformed Upper Triassic turbidites. New conodont and foraminifera data indicate an Anisian to Carnian (Middle to Late Triassic) age for these hemi-pelagic Hallstatt-type limestones. The siliciclastic turbidites surrounding the Triassic limestone contain the Norian (Late Triassic) bivalve Monotis salinaria; the same species is also found in the Tauric series in Crimea. The Upper Triassic flysch in the Central Pontides is locally underlain by basaltic pillow lavas and includes kilometre-size tectonic slices of serpentinite. Both the flysch and the serpentinite are cut by an undeformed acidic intrusion with an Ar–Ar biotite age of 162 ± 4 Ma (Callovian–Oxfordian). This indicates that the serpentinite was emplaced into the turbidites before Middle Jurassic time, most probably during latest Triassic or Early Jurassic time, and that the deformation of the Triassic sequence pre-dates the Middle Jurassic. Regional geological data from the circum-Black Sea region, including widespread Upper Triassic flysch, Upper Triassic eclogites and blueschists of oceanic crustal affinity, and apparent absence of a ‘Cimmerian continent’ between the Cretaceous and Triassic accretionary complexes indicate that the latest Triassic Cimmeride orogeny was accretionary rather than collisional and is probably related to the collision and accretion of an oceanic plateau to the southern active margin of Laurasia. [ABSTRACT FROM AUTHOR]

The Black Sea region comprises Gondwana-derived continental blocks and oceanic subduction complexes accreted to Laurasia. The core of Laurasia is made up of an Archaean–Palaeoproterozoic shield, whereas the Gondwana-derived blocks are characterized by a Neoproterozoic basement. In the early Palaeozoic, a Pontide terrane collided and amalgamated to the core of Laurasia, as part of the Avalonia–Laurasia collision. From the Silurian to Carboniferous, the southern margin of Laurasia was a passive margin. In the late Carboniferous, a magmatic arc, represented by part of the Pontides and the Caucasus, collided with this passive margin with the Carboniferous eclogites marking the zone of collision. This Variscan orogeny was followed by uplift and erosion during the Permian and subsequently by Early Triassic rifting. Northward subduction under Laurussia during the Late Triassic resulted in the accretion of an oceanic plateau, whose remnants are preserved in the Pontides and include Upper Triassic eclogites. The Cimmeride orogeny ended in the Early Jurassic, and in the Middle Jurassic the subduction jumped south of the accreted complexes, and a magmatic arc was established along the southern margin of Laurasia. There is little evidence for subduction during the latest Jurassic–Early Cretaceous in the eastern part of the Black Sea region, which was an area of carbonate sedimentation. In contrast, in the Balkans there was continental collision during this period. Subduction erosion in the Early Cretaceous removed a large crustal slice south of the Jurassic magmatic arc. Subduction in the second half of the Early Cretaceous is evidenced by eclogites and blueschists in the Central Pontides and by a now buried magmatic arc. A continuous extensional arc was established only in the Late Cretaceous, coeval with the opening of the Black Sea as a back-arc basin. [ABSTRACT FROM AUTHOR]

In Northwestern Turkey, the Mississippian (Lower Carboniferous) Yılanlı Formation is composed of variegated shallow-water limestone containing rugose corals, tabulate corals and brachiopods. Six sections were sampled in the Zonguldak and Bartın areas, from east to west, there are Süzek, Topluca, Gökgöl, Kokaksu, Ulutam and Kisla sections. Among the rugose corals, a rich and diversified assemblage of Lithostrotionidae has been collected. The latter contains the species: Nemistium cf. affine, Siphonodendron ondulosum, S. martini, S. irregulare, S. pauciradiale, S. asiaticum, S. rallii sp. nov., S. scaleberense, S. kleffense, S. aff. kleffense, Lithostrotion araneum, L. vorticale, L. sp. and L.potii sp. nov. During the Moliniacian it is proposed that subcerioid colonies of S. ondulosum gave rise to cerioid colonies of Lithostrotion potii sp. nov., the latter constituting the oldest species of the genus previously considered to be Livian to Warnantian in age. This discovery led to an emendation of the phyletic lineage of the Lithostrotionidae. The biostratigraphy based on rugose corals indicates a Moliniacian (early Viséan) and Warnantian (late Viséan) age of the deposits with the absence of the intervening Livian (middle Viséan). [ABSTRACT FROM AUTHOR]

The Karadere area to the east of Safranbolu in NW Anatolia is one of the very few localities in Turkey where the contact between the Cadomian basement and the Lower Palaeozoic transgressive succession is well exposed. The Ordovician graptolite Rhabdinopora flabelliformis (Eichwald) ssp. was found in the basal part of the Bakacak Formation, indicating an Early to early Late Tremadocian age for the beginning of the Palaeozoic transgression in the Zonguldak terrane. A few metres above this occurrence, another horizon contains Paradelograptus cf. antiquus (T. S. Hall), which mainly ranges into the Late Tremadocian. Higher up in the Ordovician succession, a new graptolite bed confirms an early Darriwilian (Dw1) age for the middle part of the Karadere Formation with the occurrence of the biozonal index Levisograptus austrodentatus (Harris & Keble) and the first record of Tetragraptus cor (Strandmark) in the area. The palaeobiogeographic distribution of these Karadere fossils is in agreement with a peri-Gondwanan affinity of the Zonguldak Terrane of the Pontides, NW Anatolia, during the Early-Middle Ordovician. [ABSTRACT FROM AUTHOR]

Magmatic arcs are zones of high heat flow; however, examples of metamorphic belts formed under magmatic arcs are rare. In the Pontides in northern Turkey, along the southern active margin of Eurasia, high temperature-low pressure metamorphic rocks and associated magmatic rocks are interpreted to have formed under a Jurassic continental magmatic arc, which extends for 2800 km through the Crimea and Caucasus to Iran. The metamorphism and magmatism occurred in an extensional tectonic environment as shown by the absence of a regional Jurassic contractional deformation, and the presence of Jurassic extensional volcaniclastic marine basin in the Pontides, over 2 km in thickness, where deposition was coeval with the high- T metamorphism at depth. The heat flow was focused during the metamorphism, and unmetamorphosed Triassic sequences crop out within a few kilometres of the Jurassic metamorphic rocks. The heat for the high- T metamorphism was brought up to crustal levels by mantle melts, relicts of which are found as ultramafic, gabbroic and dioritic enclaves in the Jurassic granitoids. The metamorphic rocks are predominantly gneiss and migmatite with the characteristic mineral assemblage quartz + K-feldspar + plagioclase + biotite + cordierite ± sillimanite ± garnet. Mineral equilibria give peak metamorphic conditions of 4 ± 1 kbar and 720 ± 40 °C. Zircon U-Pb and biotite Ar-Ar ages show that the peak metamorphism took place during the Middle Jurassic at c. 172 Ma, and the rocks cooled to 300 °C at c. 162 Ma, when they were intruded by shallow-level dacitic and andesitic porphyries and granitoids. The geochemistry of the Jurassic porphyries and volcanic rocks has a distinct arc signature with a crustal melt component. A crustal melt component is also suggested by cordierite and garnet in the magmatic assemblage and the abundance of inherited zircons in the porphyries. [ABSTRACT FROM AUTHOR]

The Eocene volcano-sedimentary units in the southern part of the Eastern Pontides (NE Turkey) are confined within a narrow zone of east-west trending, semi-isolated basins in Bayburt, Gümüşhane, Şiran and Alucra areas. The volcanic rocks in these areas are mainly basalt and andesite through dacite, with a dominant calc-alkaline to rare tholeiitic tendency. Ar-Ar dating of these volcanic rocks places them between 37.7 ± 0.2 and 44.5 ± 0.2 Ma (Middle Eocene). Differences in the major and trace element variations can be explained by the fractionation of clinopyroxene ± magnetite in basaltic rocks and that of hornblende + plagioclase ± magnetite ± apatite in andesitic rocks. Primitive mantle-normalized multi-element variations exhibit enrichment of large-ion lithophile elements and to a lesser extent, of light rare earth elements, as well as depletion of high field strength elements, thus revealing that volcanic rocks evolved from a parental magma derived from an enriched mantle source. Chondrite-normalized rare earth element patterns of the aforementioned volcanic rocks resemble each other and are spoon-shaped with low-to-medium enrichment (La/Lu = 2-14), indicating similar spinel lherzolitic mantle source(s). Sr, Nd and Pb isotopic systematics imply that the volcanic rocks are derived from a subduction-modified subcontinental lithospheric mantle. Furthermore, post-collisional thickened continental crust, lithospheric delamination and a subduction-imposed thermal structure are very important in generating Tertiary magma(s). The predominantly calc-alkaline nature of Eocene volcanic rocks is associated with increasing geodynamic regime-extension, whereas tholeiitic volcanism results from local variations in the stress regime of the ongoing extension and the thermal structure, as well as the thickness of the crust and the mantle-crust source regions. Based on volcanic variety and distribution, as well as on petrological data, Tertiary magmatic activity in Eastern Pontides is closely related to post-collisional thinning of the young lithosphere, which, in turn, is caused by extension and lithospheric delamination after collisional events between the Tauride-Anatolide Platform and the Eurasian Plate. [ABSTRACT FROM AUTHOR]

Abstract: The Intra-Pontide suture is the boundary between the İstanbul and Sakarya terranes in northwest Turkey. We provide new isotopic and stratigraphical data from the Intra-Pontide suture zone, which indicate Early Cretaceous collision between the Sakarya and İstanbul terranes. These two terranes along with the Strandja Massif make up the Pontides. Metamorphic units of the Intra-Pontide suture zone are best exposed in the Armutlu Peninsula. In the eastern part of the Armutlu Peninsula, three metamorphic units crop out forming an eastward dipping thrust stack. At the base of the thrust stack there is a metaclastic-marble sequence, which is tectonically overlain by a Cretaceous subduction-accretion complex, farther up in the thrust stack there is a high-grade metamorphic unit, which represents the Proterozoic basement of the İstanbul Zone. New clastic zircon ages from the metaclastic-marble sequence indicate that deposition of the sandstones must be later than Permian (∼264Ma) possibly during Triassic. Similar Triassic metasediments are also reported in Strandja Massif. We interpret that these metasediments were deposited during Triassic along the rift flanks leading to the opening of the Intra-Pontide Ocean, which suggest a possible Early Triassic opening for the Intra-Pontide Ocean. Our new Rb–Sr mica and Sm–Nd garnet ages dates the regional metamorphism between Late Jurassic–Early Cretaceous (158–111Ma) along the Intra-Pontide suture zone, similar ages are also reported in the Strandja Massif. The metamorphic rocks of the Intra-Pontide suture are unconformably overlain by Campanian–Ypresian clastics. The collision between the İstanbul and Sakarya–Strandja terranes has occurred during Early Cretaceous and the Proterozoic basement of İstanbul terrane was reheated during this collision. [Copyright &y& Elsevier]

The Late Cretaceous--Eocene geological evolution of northwest Turkey between the Black Sea and Bursa was studied through detailed biostratigraphic characterization of eleven stratigraphic sections. The Upper Cretaceous sequence in the region starts with a major marine transgression and lies unconformably on a basement of Palaeozoic and Triassic rocks in the north (İstanbul-type basement) and on metamorphic rocks and Jurassic sedimentary rocks in the south (Sakarya-type basement). Four megasequences have been differentiated in the Late Cretaceous--Eocene interval. The first one, of Turonian to Late Campanian age, is represented by volcanic and volcanoclastic rocks in the north along the Black Sea coast, and by siliciclastic turbidites and intercalated calcarenites in the south, corresponding to magmatic arc basin and fore-arc basin, respectively. A major ridge along the present southern margin of the Kocaeli Peninsula separated these two realms. In the Late Campanian, volcanism and clastic sedimentation gave way to the widespread deposition of the pelagic limestone and marl of the Akveren Formation; only in the extreme south near Bursa are the pelagic micrites of the Akveren Formation replaced by calciturbidites and siliciclastic turbidites. The age of the Akveren Formation ranges from Late Campanian to Late Palaeocene. The third megasequence is a thick flysch wedge of Early Eocene age, which extends from north of Bursa to the Black Sea coast. The base of the Lower Eocene flysch is marked by a major unconformity. The flysch wedge marks the collision between the Pontides and the Anatolide-Tauride Block. The fourth megasequence is a thick volcanic and volcaniclastic series of late Early to Middle Eocene age, which extends from north of Bursa to the northern margin of the Armutlu Peninsula. The coherent Upper Cretaceous--Eocene stratigraphy, the laterally traceable facies belts, absence of ophiolitic slices and high pressure metamorphic rocks in the Upper Cretaceous--Tertiary series in the region between the Black Sea and Bursa indicate pre-Santonian juxtaposition of the İstanbul and Sakarya zones. [ABSTRACT FROM AUTHOR]

The Pontide magmatic belt in the Western Pontides, which developed in response to the northward subduction of the northern branches of the Tethys Ocean, consists of two different volcanic successions separated by an Upper Santonian pelagic limestone unit, the Unaz Formation. The first period of volcanism and associated sedimentation started during the Middle Turonian and lasted until the Early Santonian under the control of an extensional tectonic regime, which created horst-graben topography along the southern Black Sea region. The lower volcanic succession, the Dereköy Formation, was deposited mainly within these grabens. This extensional period probably represents the rifting of magmatic arc, giving rise to the opening of the Western Black Sea back--intra-arc basin. The Unaz Formation commonly covers horsts and grabens developed before its deposition. This formation implies sudden subsidence of the region and termination of the volcanism during the Late Santonian. This period was interpreted as the time of the beginning of the oceanic spreading in the Western Black Sea Basin. The second period of magmatism developed on the Unaz Formation was more voluminous and was active during the Campanian. Stratigraphy, contact relationships and regional correlations indicate that the deposition of the Unaz Formation and similar deep marine red pelagic sediments in the Black Sea and Eastern Mediterranean region were probably controlled by local and regional tectonic events and sea level and/or climate changes. [ABSTRACT FROM AUTHOR]

The Lower Carboniferous flysch of the Istanbul Zone in Turkey is an over 1500 m thick turbiditic sandstone–shale sequence marking the onset of the Variscan deformation in the Pontides. It overlies Lower Carboniferous black cherts and is unconformably overlain by Lower Triassic continental sandstones and conglomerates. The petrography of the Carboniferous sandstones and the geochronology and geochemistry of the detrital zircons and rutiles were studied to establish the provenance of the clastic rocks. The sandstones are feldspathic to lithic greywackes and subgreywackes with approximately equal amounts of quartz, feldspar and lithic clasts. The amount of quartz and lithic fragments decreases upwards in the sequence at the expense of feldspar. The lithic fragments are dominated by intermediate volcanic rocks, followed by metamorphic and sedimentary rock fragments. Coarse lithic fragments are generally granitoidic. In the discrimination diagrams, sandstone samples lie mainly in the field of dissected arc. A total of 218 detrital zircons and 35 detrital rutiles from four sandstone samples were analysed with laser ablation ICP-MS. The detrital zircons show a predominantly bimodal age distribution with Late Devonian to Early Carboniferous (390 to 335 Ma) and Cambrian–Neoproterozoic (640 to 520 Ma) ages. The remaining 9 % of the analysed zircons are in the 1700–2750 Ma range; zircons of the 700–1700 Ma age range are absent. The REE patterns and Th/U ratios of the zircons are consistent with a magmatic origin. With one exception (Neoproterozoic), the rutile ages are Late Devonian–Early Carboniferous and their geochemistry indicates that they were derived from amphibolite-facies metamorphic rocks. Sandstone petrography and detrital zircon–rutile ages suggest one dominant source for the Lower Carboniferous sandstones: a Late Devonian to Early Carboniferous magmatic and metamorphic province with overprinted Neoproterozoic basement. Late Devonian–Early Carboniferous magmatic and metamorphic rocks are unknown from the Eastern Mediterranean region. They are, however, widespread in central Europe. The Istanbul Zone is commonly correlated with the Avalonian terrranes in central Europe, which collided with the Armorican terranes during Carboniferous times, resulting in the Variscan orogeny. The Carboniferous flysch of the Istanbul Zone must have been derived from a colliding Armorican terrane, as indicated by the absence of 700–1700 Ma zircons and by Late Devonian–Early Carboniferous magmatism, typical features of the Armorican terranes. This suggests that during Carboniferous times the Istanbul terrane was located close to the Bohemian Massif and has been translated by strike-slip along the Trans-European Suture Zone to its Cretaceous position north of the Black Sea. [ABSTRACT FROM PUBLISHER]

Abstract: Devonian radiolarian ribbon cherts are found as olistoliths and as a thin (<100m) tectonic slice in pervasively deformed sandstone and shale in a Triassic subduction-accretion complex (Upper Karakaya Complex) in Northwest Turkey. The subduction-accretion complex also comprises exotic blocks of Lower Carboniferous and Upper Permian limestone. It lies tectonically over a thick metabasite series and is unconformably overlain by little deformed continental to shallow marine sedimentary rocks of Jurassic age. The Devonian radiolarian cherts, along with the earlier descriptions of Carboniferous and Permian radiolarian cherts from the Karakaya Complex suggest the subduction of a Late Paleozoic ocean, the Paleo-Tethys, along the southern margin of the Pontides. [Copyright &y& Elsevier]

The Turkish Pontide fold-and-thrust belt formed since the Paleozoic and is an important element in the Africa-Eurasia convergence and the resulting closure of the Neo-Tethys ocean. It has a peculiar arc-shaped geometry in its central part, along the Black Sea coast, which may have resulted from oroclinal bending. We have determined the vertical-axis rotation history of this area using paleomagnetism on Cretaceous to Eocene rocks from 47 sites and critically analyzed previously published data. We applied the same reliability criteria to all data. Our results show that late Cretaceous sites have clockwise and counterclockwise rotations perpendicular to the structural trend in the central Pontides. In the eastern Pontides, they show only local rotations. Paleocene to Eocene rocks in the central and eastern Pontides show no rotation. We conclude that the central Pontide northward arc-shaped geometry results from oroclinal bending in latest Cretaceous to earliest Paleocene times. The timing and scale of geological processes that occurred in the region make it likely that orocline formation resulted from Neo-Tethys closure between the Pontides and the metamorphic promontory of the Anatolide-Tauride Block. Earlier studies on the southerly located Çankırı Basin reveal that clockwise and counterclockwise rotations occurred in Eocene-Oligocene times. This implies that the entire region underwent continuous deformation from late Cretaceous to Eocene, caused by convergence of the Pontides and the Anatolide-Tauride Block, with a southward moving deformation front. Deformation was first localized in the northern part of the central Pontides until the Paleocene, resulting in oroclinal bending, and from at least Eocene times it shifted toward the Çankırı Basin region. [ABSTRACT FROM AUTHOR]

Six individual tectonostratigraphic units are identified within the İzmir--Ankara--Erzincan Suture Zone in the critical Erzincan area of the Eastern Pontides. The Ayıkayası Formation of Campanian--Maastrichtian age is composed of bedded pelagic limestones intercalated with polymict, massive conglomerates. The Ayikayasi Formation conformably overlies the Tauride passive margin sequence in the Munzur Mountains to the south and is interpreted as an underfilled foredeep basin. The Refahiye Complex, of possible Late Cretaceous age, is a partial ophiolite composed of ~75 % (by volume) serpentinized peridotite (mainly harzburgite), ~20 % diabase and minor amounts of gabbro and plagiogranite. The complex is interpreted as oceanic lithosphere that formed by spreading above a subduction zone. Unusual screens of metamorphic rocks (e.g. marble and schist) locally occur between sheeted diabase dykes. The Upper Cretaceous Karayaprak Mélange exhibits two lithological associations: (1) the basalt + radiolarite + serpentinite association, including depleted arc-type basalts; (2) the massive neritic limestone + lava + volcaniclastic association that includes fractionated, intermediate-composition lavas, and is interpreted as accreted Neotethyan seamount(s). The several-kilometre-thick Karadağ Formation, of Campanian--Maastrichtian age, is composed of greenschist-facies volcanogenic rocks of mainly basaltic to andesitic composition, and is interpreted as an emplaced Upper Cretaceous volcanic arc. The Campanian--Early Eocene Sütpınar Formation (~1500 m thick) is a coarsening-upward succession of turbiditic calcarenite, sandstone, laminated mudrock, volcaniclastic sedimentary rocks that includes rare andesitic lava, and is interpreted as a regressive forearc basin. The Late Paleocene-Eocene Sipikör Formation is a laterally varied succession of shallow-marine carbonate and siliciclastic lithofacies that overlies deformed Upper Cretaceous units with an angular unconformity. Structural study indicates that the assembled accretionary prism, suprasubduction zone-type oceanic lithosphere and volcanic arc units were emplaced northwards onto the Eurasian margin and also southwards onto the Tauride (Gondwana-related) margin during Campanian-Maastrichtian time. Further, mainly southward thrusting took place during the Eocene in this area, related to final closure of Tethys. Our preferred tectonic model involves northward subduction, suprasubduction zone ophiolite genesis and arc magmatism near the northerly, Eurasian margin of the Mesozoic Tethys. [ABSTRACT FROM AUTHOR]

Abstract: We provide new isotopic data from the Pontides, which substantiate the presence of a Cadomian basement with latest Proterozoic granitoids but also show the existence of Ordovician intrusives. Before the opening of the Black Sea, the Pontides formed a Palaeozoic orogenic belt at the margin of the East European Platform (Baltica) in an analogous position to the Variscan terranes in the central Europe. The Pontides consist of three terranes: The Strandja terrane has a Variscan basement with Carboniferous and Permian granitoids and an epicontinental Triassic to Jurassic sedimentary cover. The I.stanbul terrane has a Cadomian basement overlain by a sedimentary sequence of Ordovician to Carboniferous age. It underwent contractional deformation during the Late Carboniferous. The Sakarya terrane is characterized by Carboniferous high temperature metamorphism and plutonism. The boundary between the I.stanbul and Sakarya terranes forms a complex tectonic zone several tens of kilometres wide. The new age data come from this boundary zone in the Armutlu peninsula in northwest Turkey. Metagranitoids, which intrude amphibolites in the Armutlu peninsula, give latest Proterozoic and Ordovician U–Pb zircon laser ablation MC–ICP–MS and Pb–Pb evaporation ages. The latest Proterozoic (ca. 570 Ma) granitoids are similar in age to those reported previously from the basement of the I.stanbul terrane; they all form part of the widespread Pan-African granitoid plutonism on the margins of Gondwana. The Mid to Late Ordovician granitoids (460 Ma), on the other hand, probably have formed during the rifting of the I.stanbul terrane away from Gondwana during the opening of the Rheic ocean. In terms of the tectonic position, stratigraphy and geological evolution, the I.stanbul and Sakarya terranes are comparable to the Avalonia and the Armorican terrane assemblage in central Europe, respectively. [Copyright &y& Elsevier]

Abstract: The gold metallogeny of Turkey constitutes a sector of the Tethyan Eurasian Metallogenic Belt (TEMB) within the Alpine–Himalayan orogenic system that formed from Jurassic–Cretaceous to the present. This orogenic system produced many different types of deposits related to subduction, collision, post-collision and rifting processes. Gold deposits, as well as other mineral deposits of Turkey, are mainly concentrated in Late Mesozoic and Tertiary rocks. Evaluation of the gold metallogeny of Turkey is based on a GIS database compilation of known gold deposits and prospects. Currently available data show that Turkey has a gold endowment, including reserves and resources, of approximately 31.5 M oz [979 tonnes] in 51 deposits, 21 of which contain more than 0.2 M oz gold. The other 30 deposits contain a total of approximately 1 M oz [31 tonnes] gold resources. Two recent discoveries, Kisladag and Copler, currently contain total resources of 17.6 M oz Au [549 tonnes], more than 50% of the total Turkish gold endowment. Turkey possesses a wide spectrum of gold deposits related to Mesozoic and Cenozoic volcanoplutonic arcs. However, porphyry gold (copper), epithermal gold (including both high- and low-sulfidation styles), and gold-rich volcanic-associated massive sulfide (including both Kuroko- and Cyprus-types) are the most economically important to date. Orogenic gold, including listwanite-hosted, placer gold and skarn-hosted gold are relatively less important or abundant deposit types. Other potential gold systems for exploration include Carlin-type gold, detachment-fault-related gold, iron oxide–copper–gold, and gold in carbonate-replacement and manganese deposits. [Copyright &y& Elsevier]

In the Pulur complex (Sakarya Zone, Eastern Pontides, Turkey) a low-grade tectonometamorphic unit (Doğankavak) is exposed in three tectonic windows beneath a complex medium-pressure high-temperature metamorphic unit of late Carboniferous age. The thrust plane between both units is transgressively covered by Liassic conglomerates. The Doğankavak unit comprises a sequence of metabasites with MORB-type chemical compositions and phyllites, with subordinate calcareous phyllites, marbles, quarzofeldspathic schists and metacherts. This sequence is interpreted as a former accretionary complex related to the consumption of the Palaeotethys. Mineral parageneses in the metabasites allow for the distinction of two domains with slightly different peak metamorphic conditions, i.e. 375–425 °C/0.5–0.8 GPa (greenschist facies) and 400–470 °C/0.6–1.1 GPa (albite-epidote amphibolite facies). The age of metamorphism is constrained at ~ 260 Ma (early Late Permian) by two Rb-Sr mineral-whole rock ages (hornblende, phengite) and one 40Ar/39Ar single step total fusion age (phengite). In conjunction with previous data on other accretionary complexes in the Sakarya zone in Northern Turkey, the data presented in this study suggest a continuous subduction of the Palaeotethys at least from Early/Late Permian to Late Triassic and a discontinuous preservation of accretion complexes in both space and time. [ABSTRACT FROM AUTHOR]

Granier (2019) questioned the identification of a number of foraminifer species within the study of Vincent et al. (2018). We dispute his findings and provide supporting evidence for our original identifications. Our biostratigraphic work was carried out to support the strontium isotope stratigraphy study of an Upper Jurassic – Lower Cretaceous carbonate succession in the eastern Pontides, northeast Turkey. This was undertaken to constrain the age and duration of a number of hiatal surfaces within the succession that we proposed have geodynamic significance for the Black Sea region. Even if Granier's identifications are correct, they do not impact upon the conclusions of our study. Thus, rather than being a 'disappointing application of [a] geochemical tool', our study illustrates the utility of the powerful strontium isotope stratigraphy approach. • We dispute Granier's revision of our foraminifer identifications from NE Turkey. • We support our original interpretations with additional annotated illustrations. • The major stratigraphic gap in the section does not correspond to the Berriasian. • A Hauterivian age for the top of the section is compatible with our SIS data. • Granier's intervention does not affect the regional implications of our study. [ABSTRACT FROM AUTHOR]