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The Southeast Anatolian ophiolites outcropping in the Southeast Anatolian Orogenic Belt (Southeast of Turkey) mark the closure of the southern branch of the Neotethys Ocean associated with the collision between the Arabian Plate and Anatolian microplate. We present new geochemical, zircon U–Pb age, zircon Lu–Hf, and Sr-Nd isotopic data on the Southeast Anatolian Ophiolites to understand their formation ages, magma genesis, and geotectonic implications. The ophiolites, which are related to island arc igneous rocks, consist of mantle peridotites and crustal rocks (less dunite, gabbros, sheeted dykes, massive, and pillow basalts). The flat rare-earth element (REE) patterns, depletion in Nb and Ta, and enrichment in LILEs (Ba, Rb, Th, Sr, Pb) of gabbros suggest close similarities with very low Ti (boninitic) lavas found in the forearc regions. Using laser ablation inductively coupled plasma–mass spectrometry, zircon separated from leucogabbros, diabase dykes, and plagiogranites yield U-Pb ages of 92 and 83 Ma, which are interpreted to represent the formation ages of the ophiolites. The zircons in the gabbros and plagiogranites are dominated by positive εHf(t) values (between +3.1 and +?17.45) with a few negative εHf(t) values. High εHf(t) features are consistent with derivation from Mid-oceanic Ridge Basalt (MORB)-source mantle. The negative εHf(t) values of the zircons suggest the involvement of subducted sedimentary rocks. The southeast Anatolian ophiolites represent an SSZ-type ophiolite and are part of the Late Cretaceous oceanic lithosphere of the southern branch of the Neotethys Ocean that opened during the Late Triassic and closed during the Late Cretaceous.  相似文献   
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The Guleman ophiolite,one of the most important ophiolitic massifs of the Southeast Anatolian Ophiolitic Belt,consists of a core of serpentinized mantle rocks overlain by an ultramafic sequence,layered and isotropic gabbro,and sheeted dykes.The ophiolite structurally overlies the Lower Miocene Lice Formation and is overlain by young sandstones and shales of the Upper Maashtrichtian-Lower Eocene Hazar Complex and Middle Eocene Maden Complex.The Guleman ophiolite tectonically overlain by Precambrian to Upper Triassic Bitlis metamorphic massif.The mantle peridotites compose mainly of fresh and in place serpentinized harzburgite tectonite with local bands and lenses of dunites with large-sized chromitite pods.The Guleman peridotites commonly show porphyroclastic texture,high-temperature fabrics such as kink-bands in olivines.According to microprobe analyses,the harzburgite and dunite have low Ca O and Al2O3 abundance similar to Mariana forearc,and their average Cr-(=Cr/(Cr+Al)atomic)ratio of Cr-spinelsis surprisingly high(0.63)besides Fo content of olivine is between 90.9 to 92.3 in peridotites.According to Mg#(Mg/(Mg+Fe2+))versus Cr#in spinel diagram,the degree of partial melting is higher than 35%and spinel values plot in the forearc peridotites field.The Gulemanharzburgites have low Ca O,Al2O3 and Ti O2 contents in orthopyroxene and clinopyroxene lammelles,resembling those of depleted harzburgites from modern forearcs and different from moderately depleted abyssal peridotites.Consequently,we propose that the Guleman peridotites form in a forearc setting during the subduction initiation that developed as a result of northward subduction of the southern branch of the Neo-Tethys in response to the convergence between Arabian and Anatolian plates.  相似文献   
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