Devonian to Permian evolution of the Paleo-Tethys Ocean:New evidence from U–Pb zircon dating and Sr–Nd–Pb isotopes of the Darrehanjir–Mashhad “ophiolites”,NE Iran
作者单位：State Key Laboratory of Lithospheric EvolutionInstitute of Geology and GeophysicsChinese Academy of Sciences School of Earth SciencesDamghan University Geosciences Dept.University of Texas at Dallas Department of Earth SciencesKanazawa University Department of GeologyFaculty of ScienceKafrelsheikh University Département de MinéralogieUniversité de Genève
会议名称：《中国科学院地质与地球物理研究所2015年度（第15届）学术年会》
会议日期：2016年
学科分类：070902[理学-地球化学] 070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学]
基 金：supported by the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences (Grant no.XDB03010800) to XHL the State Key Laboratory of Lithospheric Evolution,IGG-CAS to HSM IGCP#592 project “continental construction in Central Asia”
关 键 词：Paleozoic ophiolites U–Pb zircon dating Zircon εHf(t) Komatiite Supra-subduction zone-type magmatism
摘 要：Middle to Late Paleozoic ophiolites,which are remnants of the Paleo-Tethys Ocean,are aligned in two main zones in northern Iran:Darrehanjir-Fariman-Mashhad,and Rasht in the north and Jandagh-Anarak ophiolites to the *** new U-Pb zircon dating results show that the-200 km long Darrehanjir-Mashhad mafic-ultramafic body is not a single ophiolite but a composite igneous complex composed of Permian pillow lavas and pelagic sediments in fault contact with a small outcrop of Devonian intrusive and ultramafic *** intrusive rocks have U-Pb zircon ages of 380.6±3.7 Ma and 382.9±3.7 Ma respectively,-100 Ma older than published ages for gabbros and radiolarites intercalated with lavas near Mashhad and *** peridotites from the Devonian complex contain low Cr#spinel,similar to that in MORB-type *** Darrehanjir gabbros and Permian Mashhad sequences both have boninitic and calc-alkaline signatures,***δOvalues from the Devonian ferrodiorite(δO-4.6±0.3‰)are slightly lower than the 5.2 to5.4‰expected for MORB-type zircons whereas Devonian plagiogranitic zircons mostly haveδO103)and lowεNd(5.4)for both Permian and Devonian *** Darrehanjir-Mashhad rocks are characterized by radiogenicPb/Pb andPb/Pb,indicating the involvement of subducted terrigenous sediments in the *** Mashhad-Darrehanjir mafic-ultramafic complex demonstrates that this part of Paleo-Tethys evolved from oceanic crust formation above a subduction zone in Devonian time to accretionary convergence in Permian *** Paleozoic ophiolites and oceanic igneous complexes along with those of the Caucasus and Turkey in the west and Afghanistan,Turkmenistan