气候变化领域集成服务门户(CCPortal): Subduction initiation-induced rapid emplacement of garnet-bearing peridotites at a nascent forearc: Petrological and Os-Li isotopic evidence from the Purang ophiolite, Tibet

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DOI	10.1130/B35960.1
	Subduction initiation-induced rapid emplacement of garnet-bearing peridotites at a nascent forearc: Petrological and Os-Li isotopic evidence from the Purang ophiolite, Tibet
	Gong, Xiao-Han; Xu, Ji-Feng; Shi, Ren-Deng; Su, Ben-Xun; Huang, Qi-Shuai; Huang, Xiao-Xiao
通讯作者	Xu, JF (通讯作者)
发表日期	2022
ISSN	0016-7606
EISSN	1943-2674
起始页码	722
结束页码	738
卷号	134 期号:3-4
英文摘要	Garnet-bearing peridotites commonly occur in the deeper parts of mature or thickened oceanic lithosphere, and are rarely exhumed and emplaced onto the seafloor. The Purang ophiolitic peridotites in south Tibet contain rare symplectite pseudomorphs after garnet, offering a unique window into the still poorly understood evolution of the deep oceanic lithosphere. Here, integrated petrologic and Os-Li isotopic data are used to constrain the evolution and dynamics of emplacement for these garnet peridotite protoliths. The Purang peridotites show wide variations of chemical compositions (spinel Cr#: 0.2-0.8) and Os model ages (up to 2.0 Ga), thus representing a piece of heterogeneous oceanic mantle lithosphere. Dunite channels show two distinctive groups of Cr# of spinels and Os-isotope compositions, with the low-to medium-Cr# (0.2-0.6) and high-Cr# (0.7-0.8) dunites reflecting the reaction of host lherzolites/harzburgites with percolating mid-ocean ridge basalt-like and boninitic melts, respectively. This confirms recent subduction initiation-related melt percolation in the Purang peridotites. Coexisting olivines and pyroxenes in the peridotites show systematic Li elemental and isotopic disequilibrium, suggesting fast cooling of the peridotites to Li closure temperature shortly after the melt percolations, likely during exhumation of the peridotites onto the seafloor. This supports a close link between subduction initiation and tectonic emplacement of the Purang peridotites. Combined with other geological evidence, we suggest the Purang peridotites may originate from the deep part of old, thick oceanic lithosphere of the NeoTethys. This thick oceanic lithosphere was progressively weakened and thinned likely during widespread plume-lithosphere interaction, triggering the transformation of garnet peridotite protoliths to spinel peridotites. Subsequently, initiation of a new subduction zone along the lithospheric weakness caused rapid ascent and emplacement of the Purang peridotites at a nascent forearc.
关键词	IZU-BONIN-MARIANA YARLUNG-ZANGBO SUTURE MELT-ROCK INTERACTION PLASMA-MASS SPECTROMETRY SUPRA-SUBDUCTION OCEANIC LITHOSPHERE MANTLE XENOLITHS SOUTHERN TIBET LUOBUSA OPHIOLITE XIGAZE OPHIOLITE
语种	英语
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:000764822800002
来源期刊	GEOLOGICAL SOCIETY OF AMERICA BULLETIN
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/260633
推荐引用方式 GB/T 7714	Gong, Xiao-Han,Xu, Ji-Feng,Shi, Ren-Deng,et al. Subduction initiation-induced rapid emplacement of garnet-bearing peridotites at a nascent forearc: Petrological and Os-Li isotopic evidence from the Purang ophiolite, Tibet[J]. 中国科学院青藏高原研究所,2022,134(3-4).
APA	Gong, Xiao-Han,Xu, Ji-Feng,Shi, Ren-Deng,Su, Ben-Xun,Huang, Qi-Shuai,&Huang, Xiao-Xiao.(2022).Subduction initiation-induced rapid emplacement of garnet-bearing peridotites at a nascent forearc: Petrological and Os-Li isotopic evidence from the Purang ophiolite, Tibet.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,134(3-4).
MLA	Gong, Xiao-Han,et al."Subduction initiation-induced rapid emplacement of garnet-bearing peridotites at a nascent forearc: Petrological and Os-Li isotopic evidence from the Purang ophiolite, Tibet".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 134.3-4(2022).