Search

The Late Palaeozoic-Early Mesozoic Tethyan development of the Eastern Mediterranean region remains debatable, especially in Turkey, where alternative northward and southward subduction hypotheses are proposed. Relevant to this debate, new whole-rock geochemical data are provided here for early Carboniferous (Late Tournaisian-Late Visean; c. 340-350 Ma) tuffaceous sedimentary rocks within the cataloturan thrust sheet (Aladag nappe), eastern Taurides. The tuffs accumulated from evolved alkaline volcanism, variably mixed with terrigenous and radiolarian-rich sediments. In addition, Late Palaeozoic meta-volcanic rocks, c. 150 km farther NE, within the Binboga (= Malatya) metamorphics (a low-grade high-pressure unit), are indicative of a within-plate setting. An impersistent geochemical subduction signature in these volcanics may represent an inherited, rather than contemporaneous, subduction influence, mainly because of the absence of a continental margin arc or of arc-derived tuff. Both the Binboga metamorphics and the cataloturan thrust sheet (Aladag nappe) restore generally to the north of the relatively autochthonous Tauride carbonate platform (Geyik Dag), within the carbonate platform bordering north-Gondwana. The cataloturan thrust sheet is interpreted, specifically, as a c. E-W, deep-water, volcanically active rift that progressively infilled. Regional geological evidence suggests that melange units (Konya Complex, Afyon zone), Teke Dere unit, Lycian nappes), and Chios-Karaburun melange, E Aegean) accreted to the north-Gondwana continental margin during the late Carboniferous; this was coupled with localised calc-alkaline granitic magmatism (Afyon zone of Anatolide crustal block). We propose an interpretation in which Late Devonian-Carboniferous alkaline intra-plate volcanism relates to extension/rifting along the north-Gondwana margin. In contrast, the melange accretion and granitic magmatism could relate to short-lived late Carboniferous southward subduction that accompanied the diachronous closure of Palaeotethys. DARIUS project; John Dixon memorial fund; State Key Lab for GPMR Open fund at CUG [GPMR201702]; NSFCNational Natural Science Foundation of China (NSFC) [91755213]; TUBITAK research grantsTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [111R015, 115Y213] We thank the DARIUS project for financial support to carry out the fieldwork in the eastern Taurides (2012-2013) and for covering the cost of the chemical analysis. Yaz Demirtay kindly assisted with diagram preparation. The first author's research (AHFR) on the Carboniferous melange and turbidites was assisted by the John Dixon memorial fund. The second author's research (OP) benefitted from on-going support from the State Key Lab for GPMR Open fund (GPMR201702) at CUG, and NSFC 91755213. The third author's research on the Carboniferous and Triassic units of the central Taurides and the Karaburun Peninsula (TU) was aided by TuBTAK research grants (Nos. 111R015 and 115Y213). The manuscript benefitted from constructive reviews by Prof. Dov Avigad and Prof. O. Candan.

Cadomian realms have recently received much attention in the Alpine–Mediterranean orogenic belts, with discontinuous outcrops extending from the Alps to the İstanbul Zone, Menderes Massif, Taurides in Turkey and Iran as well. However, they have not been identified in the Sakarya Zone, northern Turkey to date. Here, we present, for the first time, zircon Usingle bondPb geochronology, zircon Hf-isotopes and trace elements as well as whole-rock geochemistry and Nd-isotopes from the Karameşe metagranitoid in the Yusufeli (Artvin) area, NE Turkey. The zircon Usingle bondPb age data demonstrate that the Karameşe metagranitoid intruded into the Precambrian basement units in the Early Cambrian (ca. 534–530 Ma). Zircon overgrowths in the Karameşe metagranitoid interpreted as a result of metamorphic overprint yielded ages of 328 Ma. This age indicates that the Sakarya Zone experienced the Variscan metamorphic events at 328 Ma. The Early Cambrian metagranitoid shows that some rocks in the basement of the Sakarya Zone date back to Precambrian in age. The Karameşe metagranitoid is an S-type granite, with high modal content of muscovite (~10%). The samples show highly peraluminous [A/CNK = molar Al2O3/(CaO + K2O + Na2O) = 1.34–1.58] and medium-K calc-alkaline geochemical affinities. The Karameşe metagranitoid displays low REE concentrations and a slight positive Eu anomaly and show slightly light REEs and LILEs enrichments, and HFSEs depletions. The samples have negative εNd(t) of −4.76 to −2.90 and εHf (t) of −4.75 to −1.08 values. These geochemical-isotopic characteristics reveal that the Karamaşe metagranitoid originated through fluid-absent muscovite dehydration melting of heterogeneous metasedimentary source rocks (mostly greywacke), with a minor input of juvenile mafic melt. We argue that the Early Paleozoic metagranitoids along the eastern Sakarya Zone is an expression of crustal thinning in the Cadomian orogenic belt in northern Gondwana, with the tectonic turnover from convergent margin to crustal extension possibly induced by break-off of Tornquist oceanic lithosphere which is a branch of Iapetus Ocean during Early Cambrian. published

The Hellenic subduction system governs the entire Aegean region through the creation of a migrating magmatic arc that has existed since the beginning of the Early Cenozoic. The Karadag Pluton is situated in the NW part of Turkey and represents one of the distinct snapshots of this subduction system during the Late Oligocene-Early Miocene Period.iod. It consists of 2 major lithological units, based on their petrographic and geochemical features, comprising: 1) main plutonic facies (SiO2 < 70 wt.%) that are dominated by hornblende- and biotite-bearing monzogranite, quartz monzonite, and granodiorite, and 2) late-stage more felsic facies (SiO2 > 70 wt.%) that are represented by cordierite-free and cordierite-bearing leucogranites. Zircon U-Pb laser ablation inductively-coupled plasma mass spectrometry and K-Ar dating revealed crystallization and cooling ages of 23.9 +/- 0.5 Ma and 20.2 +/- 0.9 Ma for the main plutonic bodies, and 22.0 +/- 1.1 Ma for the leucogranite facies, respectively. The pluton had a high-K calc-alkaline affinity and exhibited a metaluminous to peraluminous (aluminum saturation index of

This study presents the Pb isotope values of the galenas and the wall rocks related to the Pb–Zn mineralizations in the Biga Peninsula which include two different continental crusts; Sakarya Zone and Rhodope Massif. Pb–Zn mineralizations in the Sakarya fragment in Biga Peninsula have higher 207Pb/204Pb (15.677–15.710, avg: 15.688) and 208Pb/204Pb (38.895–39.000, avg: 38.935) ratios compared to the Rhodope fragment in Biga Peninsula ratios (15.650–15.709, avg: 15.668 for 207Pb/204Pb, 38.771–38.947, avg: 38.814 for 208Pb/204Pb), though the 206Pb/204Pb ratios of both crusts (Sakarya fragment in Biga Peninsula: 18.749–18.782, avg: 18.763; Rhodope fragment in Biga Peninsula: 18.750–18.839, avg: 18.802) are similar. Also, both crusts have radiogenic 207Pb/204Pb ratios indicating an orogenic source of lead. The Pb isotope ratios of the wall rocks related to the mineralizations in the Sakarya fragment were plotted in close, though different areas on uranogenic and thorogenic diagrams. Only the areas of Oligo-Miocene plutonics and Miocene volcanics, considered to be the main sources of mineralization, coincide with each other. The Pb isotope ratios of galena samples from the Sakarya fragment overlap the Permo-Triassic metamorphic rock (Karakaya Complex) area and seem to be related to the Cenozoic magmatism, both in proximity and trend, in uranogenic-thorogenic diagrams. The intense calc-alkaline magmatism occurrence that followed the closure of the Neo-Tethys Ocean appears to have played an essential role in forming the Pb–Zn mineralizations of the Sakarya fragment by leaching lead from the wall rocks. This study has utilized the Pb isotope ratios of the wall rocks related to mineralizations in the Rhodope fragment from a previous study (one sample for each reservoir). With this data, the magmatic effect on the Pb–Zn mineralizations in the Rhodope fragment is shown to be more dominant compared to those of the Sakarya fragment. In addition, through this study, it was determined that the Pb isotope ratios of two different continental crusts (Sakarya and Rhodope fragments) which came together with the Intra-Pontide suture zone followed two different trends. The Pb isotope compositions of Pb–Zn deposits in Rhodope Massif (both in the fragments of the Balkans and Biga Peninsula) were also compared in this study. According to the Pb isotope ratios, crustal thickness, and amount of the acidic rocks, the crustal materials are dominant in the western part of the massif. These findings also indicate that the western part of the massif is typical for Pb–Zn deposits whereas the eastern part of the massif is typical for the Cu–Au deposits.

The study was performed in central-northern Anatolia (from Ankara to Amasya) to investigate the relationships of the Sakarya Zone units and the Izmir–Ankara–Erzincan suture (IAES) melange. It reveals that all the Sakarya Zone units are metamorphic and three main tectonostratigraphic units have been distinguished for the first time: the BAA (metasiliciclastic rocks capped by metacarbonates and varicoloured phyllite), the BKC (poly-metamorphic garnet-bearing micaschist and metabasite with a well-preserved relict HP–LT amphibole in a low-amphibolitic to greenschist-facies framework) and the AMC (meta-arkose passing vertically to carbonate–phyllitic alternations and, then, to a thick succession of prevailing acidic to intermediate–basic metavolcanites and volcanic-rich metasediments). The BAA and AMC, whose metamorphic frameworks are of Cimmerian age, underlie the Mesozoic carbonate cover sequences (e.g. t2-3, j3–k1) that often show tectonic detachments and slicing. The piling up of the BAA above the HP–LT BKC can be correlated to the tectonic superposition of two similar units (i.e. the Cimmerian Çangaldağ Complex and the Alpine Middle–Upper Cretaceous Domuzdağ Complex, respectively) defined by previous authors in other sectors of the Central Pontides front. The ophiolitic melange generally underlies the Sakarya Zone, but locally (e.g. SE of Amasya) tectonically rests above the latter, probably owing to back-thrusting that occurred during the Tertiary syn-collisional shortenings and the later strike-slip tectonics. We hypothesize that, also in these areas, the Sakarya Zone–IAES consists of a complex tectonic stack of different units, belonging to different palaeogeographic domains and orogenic events (Cimmerian versus Alpine orogenies), but originated within a single long-lived (since Late Triassic to Paleocene/Eocene times), prograding subduction–accretion system in front of the Laurasian continent.

The initiation of the break-off of the northern branch of the Neotethyan oceanic lithosphere is an important but poorly understood event in the geology of the Sakarya Zone (SZ) in northeastern Turkey. Although it is well-known that Latest Cretaceous intrusives (~70 Ma) and early Eocene adakitic magmatic rocks are present in the eastern SZ, the outcrops of the early Eocene non-adakitic rocks are very limited, and their tectono-magmatic evolution has not been studied. We describe a small outcrop of non-adakitic quartz diorite porphyry in the Kov area of the Gumushane region in northeastern Turkey. The genesis of these porphyries is significant in evaluating the syn- to post-collision-related magmatism. The LA-ICP-MS zircon U-Pb dating revealed that the Kov quartz diorite porphyries (KQDP) formed at ca. 50 Ma, coeval with adakitic rocks, and ~20 Myr later than the slab roll-back-related intrusive rocks. The KQDPs are calc-alkaline in composition and enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and depleted in high field strength elements (HFSEs; e.g., Nb, Ta, Ti), with significant negative anomalies of Nb, Ta, and Ti but positive anomalies of Th, U, and Pb. Isotopic compositions of the samples show limited range of variation and slight enrichment of 87Sr/86Sr(t) (0.70489 to 0.70555), eNd(t) (−1.4 to −1.2) with TDM of 1.11 to 1.61 Ga. Pb isotopic ratios of the samples point to an enriched mantle source. They were likely crystallized from the melt that originated from an EM2-type spinel-facies subcontinental lithospheric mantle (SCLM), followed by the fractionation with insignificant crustal assimilation. The SCLM was metasomatically enriched, and the metasomatic agent was likely H2O-rich fluids rather than sediments released from subducting oceanic crust during the Late Cretaceous closure of the Neotethyan oceanic lithosphere. In conjunction with the geological background and previous data, we propose that the generation of the KQDPs resulted from a slab break-off event that caused ascending or infiltration of hot asthenosphere, triggering mantle melting. Such sporadic occurrences of the KQDPs, with coeval adakitic rocks in the SZ, are likely associated with the onset of extensional tectonics due to the earlier stage of slab break-off along the region during the early Eocene period.

17th International Multidisciplinary Scientific Geoconference, SGEM 2017 -- 29 June 2017 through 5 July 2017 -- -- 130787, The Sakarya zone in Anatolia is a continental fragment >1500 km long and 120 km wide. This continent is divided into three zones: western, central and eastern. This volcanism is related to western Anatolia orogenic belt around Sakarya zone which produced Late Eocene-Late Miocene-aged mainly acidic and intermediate volcanic rocks. They are mainly composed of andesite, dacite, and latite lavas with associated pyroclastic rocks. The central Sakarya zone volcanic unit is mainly composed of Eocene-aged andesite and dacite lavas, agglomerates and lithic tuffs. In the eastern Sakarya zone, the volcanic complex consists of a plug dome and lava flows with compositions ranging from basic andesite to rhyolite. Two distinct episodes of volcanic activity in this zone occurred in western and central Sakarya zone around Early and Late Miocene. The Early Miocene volcanic sequence ranges in composition from K-rich basaltic trachyandesite to rhyolite, whereas the Late Miocene volcanic rocks are alkali basalt in composition.The Eocene-Miocene volcanic rocks of the Sakarya zone are mainly high-K calc-alkaline. They display enrichment in LILE and LREE relative to HFSE. These characteristics indicate an enriched mantle source region(s) carrying a subduction component inherited from pre-collision subduction events. The removal of subduction results in the progressive change of the chemistry of the volcanism from calc-alkaline to midly alkaline to alkaline through time was accompanied by crustal to lithosperic scale extension and decreasing amounts of subduction signature and crustal contamination. © SGEM2017. All Rights Reserved.