The G?ksun(Kahramanmaras)ophiolite(GKO),cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south,is located in the EW-trending lower nappe zone of the southeast Anatolian o...The G?ksun(Kahramanmaras)ophiolite(GKO),cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south,is located in the EW-trending lower nappe zone of the southeast Anatolian orogenic belt(Turkey).It exhibits a complete oceanic lithospheric section and overlies the Middle Eocene Maden Group/Complex with a tectonic contact at its base.The ophiolitic rocks and the tectonically overlying Malatya metamorphic(continental)unit were intruded by I-type calc-alkaline Late Cretaceous granitoid(~81-84 Ma).The ultramafic to cumulates in the GKO are represented by wehrlite,plagioclase wehrlite,olivine gabbro and gabbro.The crystallization order for the cumulate rocks is as follows:olivine±chromian spinel→clinopyroxene→plagioclase.The major and trace element geochemistry as well as the mineral chemistry of the ultramafic to mafic cumulate rocks suggest that the primary magma generating the GKO is compositionally similar to that observed in the modern island-arc tholeiitic sequences.The mineral chemistry of the ultramafic to mafic cumulates indicates that they were derived from a mantle source that was previously depleted by earlier partial melting events.The highly magnesian olivine(Fo77-83),clinopyroxene(Mg#of 82-90)and the highly Ca-plagioclase(An81-89)exhibit a close similarity to those,which formed in a supra-subduction zone(SSZ)setting.The field and the geochemical evidence suggest that the GKO formed as part of a much larger sheet of oceanic lithosphere,which accreted to the base of the Tauride active continental margin,including the ispendere,K?mürhan and the Guleman ophiolites.The latter were contemporaneous and genetically/tectonically related within the same SSZ setting during the closure of the Neotethyan oceanic basin(Berit Ocean)between the Taurides to the north and the Bitlis-Pütürge massif to the south during the Late Cretaceous.展开更多
The southeastern Anatolia comprises numbers of tectono-magmatic]stratJgraphic units such as the metamorphic massifs, the ophiolites, the volcanic arc units and the granitoid rocks. All of them play important role for ...The southeastern Anatolia comprises numbers of tectono-magmatic]stratJgraphic units such as the metamorphic massifs, the ophiolites, the volcanic arc units and the granitoid rocks. All of them play important role for the late Cretaceous evolution of the southern Neotethys. The spatial and temporal relations of these units suggest the progressive development of coeval magmatism and thrusting during the late Cretaceous northward subduction/accretion. Our new U-Pb zircon data from the rhyolitic rocks of the wide-spread volcanic arc unit show ages of （83.1 ± 2.2）-（74.6 ± 4.4） Ma. Comparison of the ophiolites, the volcanic arc units and the granitoids suggest following late Cretaceous geological evolution. The ophiolites formed in a suprasubduction zone （SSZ） setting as a result of northward intra-oceanic subduction. A wide-spread island-arc tholeiitic volcanic unit developed on the top of the SSZ-type crust during 83 75 Ma. Related to regional plate convergence, northward under-thrusting of SSZ-type ophiolites and volcanic arc units was initiated beneath the Tauride platform （Malatya-Keban） and followed by the intrusion of I-type calc-alkaline volcanic arc granitoids during 84 82 Ma. New U-Pb ages from the arc-related volcanic-sedimentary unit and granitoids indicate that under-thrusting of ophiolites together with the arc-related units beneath the Malatya-Keban platform took place soon after the initiation of the volcanic arc on the top of the SSZ- type crust. Then the arc-related volcanic-sedimentary unit continued its development and lasted at - 75 Ma until the deposition of the late Campanian-Maastrichtian shallow marine limestone. The subduction trench eventually collided with the Bitlis-Pfitfirge massif giving rise to HP-LT meta- morphism of the Bitlis massif. Although the development of the volcanic arc units and the granitoids were coeval at the initial stage of the subduction/accretion both tectono-magmatic units were genetically different from each other.展开更多
The Tauride ophiolites lie on the northern and southern flanks of an E-W-trending Tanride carbonate platform. They mainly consist of three tectonic units namely in ascending order, ophiolitic melange, sub-ophiolitic m...The Tauride ophiolites lie on the northern and southern flanks of an E-W-trending Tanride carbonate platform. They mainly consist of three tectonic units namely in ascending order, ophiolitic melange, sub-ophiolitic metamorphic sole and oceanic lithospheric remnants. They were generated above intra-oceanic subduction zones and emplaced over the Tauride carbonate platform from different Neotethyan oceanic basins in the Late Cretaceous. Tauride ophiolites from west to east are described and reviewed. All are underlain by well-preserved dynamothermal metamorphic soles of varied structural thicknesses up to 500 m that have a constant structural position between ophiolitic melange below and harzburgitic mantle tectonites above and display typical inverted metamorphic sequences from amphibolite facies above to greenschist facies below. The metamorphic soles are shown to have evolved during the initiation of subduction and emplacement processes. In the PozantlKarsantl area the contact between the metamorphic sole and the overlying serpentinized harzburgites is characterized by a 1.5-2-m-thick zone of sheared serpentinized harzburgitic mantle intercalated with amphibolites and cut by thick mafic dykes （7-8 m） which postdate intraoceanic metamorphism and high-temperature ductile deformation. This contact is interpreted as an intra-oceanic decoupling surface along which volcanics from the upper levels of the down-going plate were metamorphosed to amphibolite facies and accreted to the base of the hanging wall plate. The metamorphic soles and overlying ophiolitic rocks were intruded by numerous isolated post-metamorphic diabase dykes filled by island arc tholeiitic magma. Subduction initiation and roll-back processes best explain the structural and petrological relationships of Late Cretaceous ophiolite genesis, metamorphic sole formation and subsequent dyke emplacement of the Tauride ophiolites.展开更多
基金supported by TüBITAK (YDABCAG199Y011) and the Cukurova University Scientific Research Projects (MMF2002BAP41)the Open Fund (GPMR201702) of State Key Lab of Geological Processes and Mineral Resources,China University of Geosciences,Wuhansubsidy by the Russian Government to support the Program of competitive growth of Kazan Federal University
文摘The G?ksun(Kahramanmaras)ophiolite(GKO),cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south,is located in the EW-trending lower nappe zone of the southeast Anatolian orogenic belt(Turkey).It exhibits a complete oceanic lithospheric section and overlies the Middle Eocene Maden Group/Complex with a tectonic contact at its base.The ophiolitic rocks and the tectonically overlying Malatya metamorphic(continental)unit were intruded by I-type calc-alkaline Late Cretaceous granitoid(~81-84 Ma).The ultramafic to cumulates in the GKO are represented by wehrlite,plagioclase wehrlite,olivine gabbro and gabbro.The crystallization order for the cumulate rocks is as follows:olivine±chromian spinel→clinopyroxene→plagioclase.The major and trace element geochemistry as well as the mineral chemistry of the ultramafic to mafic cumulate rocks suggest that the primary magma generating the GKO is compositionally similar to that observed in the modern island-arc tholeiitic sequences.The mineral chemistry of the ultramafic to mafic cumulates indicates that they were derived from a mantle source that was previously depleted by earlier partial melting events.The highly magnesian olivine(Fo77-83),clinopyroxene(Mg#of 82-90)and the highly Ca-plagioclase(An81-89)exhibit a close similarity to those,which formed in a supra-subduction zone(SSZ)setting.The field and the geochemical evidence suggest that the GKO formed as part of a much larger sheet of oceanic lithosphere,which accreted to the base of the Tauride active continental margin,including the ispendere,K?mürhan and the Guleman ophiolites.The latter were contemporaneous and genetically/tectonically related within the same SSZ setting during the closure of the Neotethyan oceanic basin(Berit Ocean)between the Taurides to the north and the Bitlis-Pütürge massif to the south during the Late Cretaceous.
基金a part of Ph.D study of Fatih KaraoglanFinancial support from the TBITAK(Project No.106Y231)+1 种基金Cukurova University Research Foundation(Project No.MMF2009D11)International Research Fellowship Programme supported by TUBITAK-BIDEB
文摘The southeastern Anatolia comprises numbers of tectono-magmatic]stratJgraphic units such as the metamorphic massifs, the ophiolites, the volcanic arc units and the granitoid rocks. All of them play important role for the late Cretaceous evolution of the southern Neotethys. The spatial and temporal relations of these units suggest the progressive development of coeval magmatism and thrusting during the late Cretaceous northward subduction/accretion. Our new U-Pb zircon data from the rhyolitic rocks of the wide-spread volcanic arc unit show ages of （83.1 ± 2.2）-（74.6 ± 4.4） Ma. Comparison of the ophiolites, the volcanic arc units and the granitoids suggest following late Cretaceous geological evolution. The ophiolites formed in a suprasubduction zone （SSZ） setting as a result of northward intra-oceanic subduction. A wide-spread island-arc tholeiitic volcanic unit developed on the top of the SSZ-type crust during 83 75 Ma. Related to regional plate convergence, northward under-thrusting of SSZ-type ophiolites and volcanic arc units was initiated beneath the Tauride platform （Malatya-Keban） and followed by the intrusion of I-type calc-alkaline volcanic arc granitoids during 84 82 Ma. New U-Pb ages from the arc-related volcanic-sedimentary unit and granitoids indicate that under-thrusting of ophiolites together with the arc-related units beneath the Malatya-Keban platform took place soon after the initiation of the volcanic arc on the top of the SSZ- type crust. Then the arc-related volcanic-sedimentary unit continued its development and lasted at - 75 Ma until the deposition of the late Campanian-Maastrichtian shallow marine limestone. The subduction trench eventually collided with the Bitlis-Pfitfirge massif giving rise to HP-LT meta- morphism of the Bitlis massif. Although the development of the volcanic arc units and the granitoids were coeval at the initial stage of the subduction/accretion both tectono-magmatic units were genetically different from each other.
基金Cukurova University Research Foundation (Nos.MMF99.22,MMF2000.22,MMF2001.13,MMF2001.33,MMF2002BAP41,MMF2003BAP16,MMF2011BAP13,and MMF2011BAP26)Turkish Academy of Sciences (No.TüBA-GEBIP/2003-111)TüBITAK (Nos.199Y011,102Y041,106Y231,and 113Y412)
文摘The Tauride ophiolites lie on the northern and southern flanks of an E-W-trending Tanride carbonate platform. They mainly consist of three tectonic units namely in ascending order, ophiolitic melange, sub-ophiolitic metamorphic sole and oceanic lithospheric remnants. They were generated above intra-oceanic subduction zones and emplaced over the Tauride carbonate platform from different Neotethyan oceanic basins in the Late Cretaceous. Tauride ophiolites from west to east are described and reviewed. All are underlain by well-preserved dynamothermal metamorphic soles of varied structural thicknesses up to 500 m that have a constant structural position between ophiolitic melange below and harzburgitic mantle tectonites above and display typical inverted metamorphic sequences from amphibolite facies above to greenschist facies below. The metamorphic soles are shown to have evolved during the initiation of subduction and emplacement processes. In the PozantlKarsantl area the contact between the metamorphic sole and the overlying serpentinized harzburgites is characterized by a 1.5-2-m-thick zone of sheared serpentinized harzburgitic mantle intercalated with amphibolites and cut by thick mafic dykes （7-8 m） which postdate intraoceanic metamorphism and high-temperature ductile deformation. This contact is interpreted as an intra-oceanic decoupling surface along which volcanics from the upper levels of the down-going plate were metamorphosed to amphibolite facies and accreted to the base of the hanging wall plate. The metamorphic soles and overlying ophiolitic rocks were intruded by numerous isolated post-metamorphic diabase dykes filled by island arc tholeiitic magma. Subduction initiation and roll-back processes best explain the structural and petrological relationships of Late Cretaceous ophiolite genesis, metamorphic sole formation and subsequent dyke emplacement of the Tauride ophiolites.
