Paleozoic post-collisional magmatism and high-temperature granulite-facies metamorphism coupling with lithospheric delamination of the East Kunlun Orogenic Belt,NW China  

作　　者：Qian Wang Jiao Zhao Chuanlin Zhang Shengyao Yu Xiantao Ye Xiaoqiang Liu 

机构地区：[1]College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,China [2]Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China [3]State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China [4]College of Oceanography,Hohai University,Nanjing 210098,China [5]Key Lab of Submarine Geosciences and Prospecting Techniques,MOE,Institute for Advanced Ocean Study,College of Marine Geosciences,Ocean University of China,Qingdao 266100,China

出　　处：《Geoscience Frontiers》2022年第1期96-113,共18页地学前缘（英文版）

基　　金：supported by the Fundamental Research Funds for the Central Universities(No.2019B00414);Open Fund of the Key Laboratory of Marine Geology and Environment Chinese Academy of Sciences(No.MGE2020KG03);the PHD early development program of East China University of Technology(No.DHBK2018035)。

摘　　要：Lithosphere extension and upwelling of asthenosphere at post-collisional stage of an orogenic cycle generally induce diverse magmatism and/or associated high-temperature metamorphism. Nevertheless, the intimate coexistence of post-collisional magmatic activity and high-temperature metamorphism is rare.In this contribution, a lithological assemblage composing of diverse magmatic rocks deriving from distinct magma sources and coeval high-temperature metamorphism was identified in eastern Kunlun.Petrography, ages, mineral chemistry and whole-rock geochemistry demonstrated that those intimately coexistent diverse rocks were genetically related to post-collisional extension. The garnet-bearing mafic granulites in Jinshuikou area interior of the East Kunlun Orogenic Belt are mainly composed of garnet,orthopyroxene, and plagioclase, with peak metamorphic P–T conditions of ~ 701–756 ℃and 5.6–7.0 kbar,representing a granulite-facies metamorphism at 409.7 ± 1.7 Ma. The diverse contemporaneous magmatic rocks including hornblendites, gabbros and granites yield zircon U–Pb ages of 408.6 ± 2.5 Ma,413.4 ± 4.6 Ma, and 387–407 Ma, respectively. The hornblendites show N-MORB-like REE patterns with(La/Sm)Nvalues of 0.85–0.94. They have positive zircon εHf(t) values of 0.1–4.9 and whole-rock εNd(t) values of 3.9–4.7 but relatively high(^(87)Sr/^(86)Sr)_(i)values of 0.7081 to 0.7088. These features demonstrate that the hornblendites derived from a depleted asthenospheric mantle source with minor continental crustal materials in source. As for the gabbros, they exhibit arc-like elemental signatures, low zircon εHf(t) values(-4.3 to 2.5) and variable whole-rock εNd(t) values(-4.9 to 1.2) as well as high(^(87)Sr/86 Sr)ivalues(0.7068 to 0.7126), arguing for that they were originated from partial melting of heterogeneous lithospheric mantle anteriorly metasomatized by subducted-sediment released melts. Geochemistry of the granites defines their strongly peraluminous S-type signatures. Zircons from the granites yie

关 键 词：East Kunlun orogenic belt Post-collisional extensional collapse MAGMATISM High-temperature metamorphism Crust-mantle interaction 

分 类 号：P534.4[天文地球—古生物学与地层学] P588.3[天文地球—地质学] P597.3