气候变化领域集成服务门户(CCPortal): Mineralogical and Re-Os isotope constraints on fluid- and melt-rock interactions and the origin of mantle peridotites from the Amdo ophiolite, northern Tibet

CCPortal

DOI	10.1016/j.lithos.2021.106543
	Mineralogical and Re-Os isotope constraints on fluid- and melt-rock interactions and the origin of mantle peridotites from the Amdo ophiolite, northern Tibet
	Wu, Kang; Shi, Ren-Deng; Huang, Qi-Shuai; Gong, Xiao-Han; Chen, Sheng-Sheng; Yang, Jing-Sui
通讯作者	Shi, RD (通讯作者)
发表日期	2021
ISSN	0024-4937
EISSN	1872-6143
卷号	406
英文摘要	Ophiolites from the Bangong-Nujiang Suture Zone in the central part of the Tibetan Plateau represent relics of Neo-Tethyan oceanic lithosphere. Here we present the results of a detailed mineralogical and Os isotopic study of mantle peridotites of the Amdo ophiolite, which provide new insights into the origin of the peridotites and their diverse melt/fluid-peridotite reactions. The Amdo ophiolite comprises mantle peridotites, mafic-ultramafic cumulates, massive gabbros, diabases, and pillow basalts. The mantle peridotites are mainly refractory harzburgites, composed of olivine (Ol, 65%-85%), orthopyroxene (Opx, 12%-35%), clinopyroxene (Cpx, <4%), and Cr-spinel (Cr-Spl, similar to 2%). Most olivine grains (Ol-I) are protogranular, locally enclosed in orthopyroxene and Cr-spinel, and have high Fo values (91.1-92.9) and NiO contents (0.29-0.44 wt%), typical of residual origin. In contrast, interstitial olivines (Ol-II) have low Fo values (67.2-84.7) and NiO contents (<0.05 wt%), but extremely high MnO contents (0.28-1.65 wt%), suggesting metasomatism by carbonate-bearing fluids. Hypidiomorphic-granular clinopymxene grains (Cpx-I) have high Mg# values (similar to 94.5) and low Al2O3 (average 1.26 wt%) and Na2O (<0.19 wt%) contents, typical of residual phases after melting. However, clinopyroxene coronas (Cpx-II) around orthopyroxene have higher Na2O contents (0.24-1.06 wt%), indicative of mantle metasomatism by melts. Osmium isotopic compositions in the harzburgites vary from subchondritic to suprachondritic (Os-187/Os-188 ratios: 0.11716-0.13284). The subchondritic Os isotopic compositions (0.11716-0.12367) correspond to TRD model ages of 0.76-1.56 Ga, suggesting Mesoproterozoic mantle depletion events. On the other hand, several harzburgites with low Os (0.29-0.86 ppb) and suprachondritic Os-187/Os-188 ratios (0.12823-0.13284) reflect the overprinting of original Os budgets and Os isotopic compositions by percolating melts or fluids. The combined mineralogical and Os isotopic compositions suggest that the Amdo peridotites represent a mixture of ancient subcontinental lithospheric mantle (SCLM) and Mesozoic oceanic lithosphere, which were subsequently infiltrated by carbonate-bearing fluids and silicate melts in a supra-subduction zone.
关键词	NUJIANG SUTURE ZONE OCEANIC UPPER-MANTLE MID-ATLANTIC RIDGE ABYSSAL PERIDOTITES TECTONIC EVOLUTION SUBDUCTION INITIATION PODIFORM CHROMITITES ELEMENT COMPOSITION LUOBUSA OPHIOLITE MORB MANTLE
英文关键词	Melt-rock reaction; Metasomatic clinopyroxene; Amdo ophiolite; Bangong-Nujiang Suture Zone (BNSZ); Tibet
语种	英语
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
WOS类目	Geochemistry & Geophysics ; Mineralogy
WOS记录号	WOS:000724782600001
来源期刊	LITHOS
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/260324
推荐引用方式 GB/T 7714	Wu, Kang,Shi, Ren-Deng,Huang, Qi-Shuai,et al. Mineralogical and Re-Os isotope constraints on fluid- and melt-rock interactions and the origin of mantle peridotites from the Amdo ophiolite, northern Tibet[J]. 中国科学院青藏高原研究所,2021,406.
APA	Wu, Kang,Shi, Ren-Deng,Huang, Qi-Shuai,Gong, Xiao-Han,Chen, Sheng-Sheng,&Yang, Jing-Sui.(2021).Mineralogical and Re-Os isotope constraints on fluid- and melt-rock interactions and the origin of mantle peridotites from the Amdo ophiolite, northern Tibet.LITHOS,406.
MLA	Wu, Kang,et al."Mineralogical and Re-Os isotope constraints on fluid- and melt-rock interactions and the origin of mantle peridotites from the Amdo ophiolite, northern Tibet".LITHOS 406(2021).