TY - JOUR A1 - Oberhänsli, Roland A1 - Koralay, E. A1 - Candan, Osman A1 - Pourteau, Amaury A1 - Bousquet, Romain T1 - Late cretaceous eclogitic high-pressure relics in the Bitlis Massif JF - Geodinamica acta : revue de géologie dynamique et de géographie physique N2 - A new occurrence of eclogites was found in the Kesandere valley in the eastern most part of the Bitlis complex, SE Anatolia. These high-pressure (HP) relics were preserved in calc-arenitic metasediments within the high-grade metamorphic basement of the Bitlis complex. The eclogitic parageneses were strongly overprinted during decompression and heating. These new eclogites locality complements the evidence of blueschist-facies metamorphism documented recently in the meta-sedimentary cover sequence of this part of the Bitlis complex. Thermodynamic calculations suggest peak conditions of ca. 480-540 degrees C/1.9-2.4GPa. New U/Pb dates of 84.4 +/-.9 and 82.4 +/-.9Ma were obtained on zircons from two Kesandere eclogite samples. On the basis of geochemical criteria, these dates are interpreted to represent zircon crystallization during the eclogitic peak stage. Kesandere eclogites differ from those previously described in the western Bitlis complex (Mt. Gablor locality) in terms of lithologic association, protolithic origin, and peak P-T conditions (600-650 degrees C/1.0-2.0GPa, respectively). On the other hand, eclogitic metamorphism of Kesandere metasediments occurred shortly before blueschist-facies metamorphism of the sedimentary cover (79-74Ma Ar-40/Ar-39 white mica). Therefore, the exhumation of Kesandere eclogites started between ca. 82 and 79Ma, while the meta-sedimentary cover was being buried. During this short time span, Kesandere eclogite were likely uplifted from similar to 65 to 35km depth, indicating a syn-subduction exhumation rate of similar to 4.3mm/a. Subsequently, eclogite- and blueschist-facies rocks were likely retrogressed contemporarily during collision-type metamorphism (around 72-69Ma). The Bitlis HP rocks thus sample a subduction zone that separated the Bitlis-Puturge (Bistun?) block from the South-Armenian block, further north. To the south, Eocene metasediments of the Urse formation are imbricated below the Bitlis complex. They contain (post Eocene) blueschists, testifying separation from the Arabian plate and southward migration of the subduction zone. The HT overprint of Kesandere eclogites can be related to the asthenospheric flow provoked by subducting slab retreat or break off. KW - eclogites KW - zircon KW - U KW - Pb ages KW - E Anatolia KW - subduction-collision Y1 - 2013 U6 - https://doi.org/10.1080/09853111.2013.858951 SN - 0985-3111 SN - 1778-3593 VL - 26 IS - 3-4 SP - 175 EP - 190 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Koralay, O. E. A1 - Candan, Osman A1 - Chen, F. A1 - Akal, Cemal B. A1 - Oberhänsli, Roland A1 - Satir, M. A1 - Dora, O. O. T1 - Pan-African magmatism in the Menderes Massif - geochronological data from leucocratic tourmaline orthogneisses in western Turkey JF - International journal of earth sciences N2 - The Menderes Massif, exposed in western Anatolia, is a metamorphic complex cropping out in the Alpine orogenic belt. The metamorphic rock succession of the Massif is made up of a Precambrian basement and overlying Paleozoic-early Tertiary cover series. The Pan-African basement is composed of late Proterozoic metasedimentary rocks consisting of partially migmatized paragneisses and conformably overlying medium- to high-grade mica schists, intruded by orthogneisses and metagabbros. Along the southern flank of the southern submassif, we recognized well-preserved primary contact relationship between biotite and leucocratic tourmaline orthogneisses and country rocks as the orthogneisses represent numerous large plutons, stocks and vein rocks intruded into a basement of garnet mica schists. Based on the radiometric data, the primary deposition age of the precursors of the country rocks, garnet mica schist, can be constrained between 600 and 550 Ma (latest Neoproterozoic). The North Africa-Arabian-Nubian Shield in the Mozambique Belt can be suggested as the possible provenance of these metaclastics. The intrusion ages of the leucocratic tourmaline orthogneisses and biotite orthogneisses were dated at 550-540 Ma (latest Neoproterozoic-earliest Cambrian) by zircon U/Pb and Pb/Pb geochronology. These granitoids represent the products of the widespread Pan-African acidic magmatic activity, which can be attributed to the closure of the Mozambique Ocean during the final collision of East and West Gondwana. Detrital zircon ages at about 550 Ma in the Paleozoic muscovite-quartz schists show that these Pan-African granitoids in the basement form the source rocks of the cover series of the Menderes Massif. KW - Menderes Massif KW - Leucocratic tourmaline orthogneisses KW - Pan-African magmatism KW - Zircon U/Pb and Pb-Pb ages KW - Mozambique Ocean KW - Gondwanaoberh Y1 - 2012 U6 - https://doi.org/10.1007/s00531-012-0775-2 SN - 1437-3254 VL - 101 IS - 8 SP - 2055 EP - 2081 PB - Springer CY - New York ER - TY - JOUR A1 - Candan, Osman A1 - Koralay, O. E. A1 - Akal, Cemal B. A1 - Kaya, O. A1 - Oberhänsli, Roland A1 - Dora, O. O. A1 - Konak, N. A1 - Chen, F. T1 - Supra-Pan-African unconformity between core and cover series of the Menderes Massif/Turkey and its geological implications JF - Precambrian research N2 - Well-preserved primary contact relationships between a Late Proterozoic metasedimentary and the metagranitic core and Palaeozoic cover series of the Menderes Massif have been recognized in the eastern part of the Cine submassif on a regional-scale. Metaconglomerates occur as laterally discontinuous channel-fill bodies close the base of the metaquartzarenite directly above the basement. The pebbles in the metaconglomerates consist mainly of different types of tourmaline-rich leucocratic granitoids, tourmalinite and schist in a sandy matrix. Petrographic features, geochemical compositions and zircon radiometric ages (549.6 +/- 3.7-552.3 +/- 3.1 Ma) of the diagnostic clasts of the metaconglomerates (e.g. leucocratic granitoids and tourmalinites) show excellent agreement with their in situ equivalents (549.0 +/- 5.4 Ma) occurring in the Pan-African basement as stocks and veins. The correlation between clasts in the metaconglomerates and granitoids of the basement suggests that the primary contact between the basement and cover series is a regional unconformity (supra-Pan-African Unconformity) representing deep erosion of the Pan-African basement followed by the deposition of the cover series. Hence the usage of 'core-cover' terminology in the Menderes Massif is valid. Consequently, these new data preclude the views that the granitic precursors of the leucocratic orthogneisses are Tertiary intrusions. KW - Menderes Massif KW - Pan-African KW - Zircon age KW - Core complex KW - Turkey Y1 - 2011 U6 - https://doi.org/10.1016/j.precamres.2010.09.010 SN - 0301-9268 VL - 184 IS - 1-4 SP - 1 EP - 23 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Candan, O. A1 - Akal, C. A1 - Koralay, O. E. A1 - Okay, A. I. A1 - Oberhänsli, Roland A1 - Prelevic, D. A1 - Mertz-Kraus, R. T1 - Carboniferous granites on the northern margin of Gondwana, Anatolide-Tauride Block, Turkey - Evidence for southward subduction of Paleotethys JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - Carboniferous metagranites with U-Pb zircon crystallization ages of 331-315 Ma crop out in the Afyon zone in the northern margin of the Anatolide-Tauride Block, which is commonly regarded as part of Gondwana during the Late Palaeozoic. They are peraluminous, calc-alkaline and are characterized by increase in Rb and Ba, decrease in Nb-Ta, and enrichment in Sr and high LILE/HFSE ratios compatible with a continental arc setting. The metagranites intrude a metasedimentary sequence of phyllite, metaquartzite and marble; both the Carboniferous metagranites and metasedimentary rocks are overlain unconformably by Lower Triassic metaconglomerates, metavolcanics and Upper Triassic to Cretaceous recrystallized limestones. The low-grade metamorphism and deformation occurred at the Cretaceous-Tertiary boundary. There is no evidence for Carboniferous deformation and metamorphism in the region. Carboniferous arc-type granites and previously described Carboniferous subduction-accretion complexes on the northern margin of the Anatolide-Tauride Block suggest southward subduction of Paleotethys under Gondwana during the Carboniferous. Considering the Variscan-related arc granites in Pelagonian and Sakarya zones on the active southern margin of Laurasia, a dual subduction of Paleotethys can be envisaged between Early Carboniferous and Late Permian. However, the southward subduction was short-lived and by the Late Permian the Gondwana margin became passive. (C) 2016 Elsevier B.V. All rights reserved. KW - Carboniferous magmatism KW - Paleotethys KW - Gondwana KW - Afyon zone KW - Anatolide-Tauride Block Y1 - 2016 U6 - https://doi.org/10.1016/j.tecto.2016.06.030 SN - 0040-1951 SN - 1879-3266 VL - 683 SP - 349 EP - 366 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Candan, O. A1 - Koralay, O. E. A1 - Topuz, G. A1 - Oberhänsli, Roland A1 - Fritz, H. A1 - Collins, A. S. A1 - Chen, F. T1 - Late Neoproterozoic gabbro emplacement followed by early Cambrian eclogite-facies metamorphism in the Menderes Massif (W. Turkey): Implications on the final assembly of Gondwana JF - Gondwana research : international geoscience journal ; official journal of the International Association for Gondwana Research N2 - Numerous (meta-)gabbroic dikes or stocks occur within the latest Neoproterozoic-early Cambrian series of the Menderes Massif (Anatolide-Tauride Block, western Turkey). These well-preserved rocks were locally converted into eclogitic metagabbros and garnet amphibolites along the contacts or shear zones. Both bulk-rock composition and compositions of igneous clinopyroxenes suggest continental tholeiitic affinity. U-Pb dating of igneous zircons from gabbroic rocks yielded a mean age of 563 +/- 1 Ma (2 sigma), indicating emplacement during the latest Neoproterozoic (Ediacaran). On the other hand, rims of zircons from eclogitic metagabbro gave 535 +/- 3 Ma (2 sigma) (early Cambrian), in addition to 558 +/- 3 Ma (2 sigma) obtained from the igneous core of zircons. These ages are interpreted as the time of high-P metamorphism and crystallization age of gabbroic protolith, respectively. Given the estimated paleogeographic position of the Anatolide-Tauride Block during the late Neoproterozoic and early Cambrian, this orogenic event can be spatially and temporally related to the northward continuity of 600-500 Ma orogenic event (Malagasy/Kuunga orogeny) extending from western margin of India, Madagascar, via Arabia up to northern margin of Gondwana beneath thick Phanerozoic cover series in Arabian Peninsula. Therefore, the high-P evolution of the basement of the Menderes Massif and associated basic intrusions can be interpreted to mark the latest stages of consumption of the basin/oceanic branches and final amalgamation of the Gondwana during the late Neoproterozoic-early Cambrian around the Arabian region. (C) 2015 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. KW - Gabbro KW - Eclogite KW - Malagasy/Kuunga orogeny KW - Menderes Massif KW - Turkey Y1 - 2016 U6 - https://doi.org/10.1016/j.gr.2015.02.015 SN - 1342-937X SN - 1878-0571 VL - 34 SP - 158 EP - 173 PB - Elsevier CY - Amsterdam ER -