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

IOCAS-IR

	Paleozoic post-collisional magmatism and high-temperature granulite-facies metamorphism coupling with lithospheric delamination of the East Kunlun Orogenic Belt, NW China
	Qian Wang; Jiao Zhao ; Chuanlin Zhang ; Shengyao Yu ; Xiantao Ye ; Xiaoqiang Liu
发表期刊	Geoscience Frontiers
ISSN	1674-9871
	2022-01-12
出版年	2022
卷号	v.13 期号:01 页码:102-119
文献类型	CNKI期刊论文
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 °C 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 eHf(t) values of 0.1–4.9 and whole-rock eNd(t) values of 3.9–4.7 but relatively high(87 Sr/86 Sr)ivalues 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 eHf(t) values(à4.3 to 2.5) and variable whole-rock eNd(t) values(à4.9 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 yield a large range of eHf(t) values ranging from à30.8 to à5.1, while the whole-rock samples yield consistent(87 Sr/86 Sr)ivalues(0.7301 to 0.7342) and negative eNd(t) values(à10.1 to à12.4). These features indicate that the S-type granites could be generated by reworking of an ancient crust. Taken together, the penecontemporaneous magmatism and metamorphic event, demonstrated the early-middle Devonian transition from crustal thickening to extensional collapse. The post-collisional mantle-derived magmas serve as an essential driving force for the high-temperature granulite-facies metamorphism and anataxis of the crust associated with formation of S-type granite. This study not only constructs a more detail Proto-Tethys evolution process of the eastern Kunlun, but also sheds new light on better understanding the intimate relationship between magmatism and metamorphism during post-collisional extensional collapse.
关键词	East Kunlun orogenic belt Post-collisional extensional collapse Magmatism High-temperature metamorphism Crust-mantle interaction
CNKI专辑号	A;
CNKI专辑名称	基础科学;
CNKI专题号	A011;
CNKI专题名称	地质学;
分类号	P534.4;P588.3;P597.3
收录类别	中科院核心 ; 中科院扩展
语种	英文;
资助项目(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)
文献类型	CNKI期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/187543
专题	中国科学院海洋研究所
作者单位	1.CollegeofEarthScienceandEngineering,ShandongUniversityofScienceandTechnology 2.KeyLaboratoryofMarineGeologyandEnvironment,InstituteofOceanology,ChineseAcademyofSciences 3.StateKeyLaboratoryofNuclearResourcesandEnvironment,EastChinaUniversityofTechnology 4.CollegeofOceanography,HohaiUniversity 5.KeyLabofSubmarineGeosciencesandProspectingTechniques,MOE,InstituteforAdvancedOceanStudy,CollegeofMarineGeosciences,OceanUniversityofChina
推荐引用方式 GB/T 7714	Qian Wang,Jiao Zhao,Chuanlin Zhang,et al. Paleozoic post-collisional magmatism and high-temperature granulite-facies metamorphism coupling with lithospheric delamination of the East Kunlun Orogenic Belt, NW China. 2022.