气候变化领域集成服务门户(CCPortal): Diachronous subduction, closure of the Proto-Tethys Ocean, and collisional accretion of microcontinents: Insights from the early Paleozoic intermediate-mafic rocks in the Amdo microcontinent of the Tibetan Plateau

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DOI	10.1130/B36689.1
	Diachronous subduction, closure of the Proto-Tethys Ocean, and collisional accretion of microcontinents: Insights from the early Paleozoic intermediate-mafic rocks in the Amdo microcontinent of the Tibetan Plateau
	Peng, Yinbiao; Yu, Shengyao; Li, Sanzhong; Liu, Yongjiang; Lv, Pei; Li, Chuanzhi; Dai, Liming; Li, Yunshuai; Gao, Xiangyu; Jiang, Xingzhou; Ji, Wentao
发表日期	2023
ISSN	0016-7606
EISSN	1943-2674
起始页码	2987
结束页码	3004
卷号	135 期号:11-12
英文摘要	The Proto-Tethys Ocean played an important role in the formation and evolution of the East Asian continental blocks, and the final closure of the Proto-Tethys Ocean may have led to the first assembly of nearly all East Asian blocks at the northern margin of Gondwana. However, controversy remains about the reconstruction of East Asian blocks at the northern margin of Gondwana. The Tibetan Plateau is located in the northern margin of Gondwana and recorded the entire tectonic evolution from continental rift and drift to subduction and collision during the early Paleozoic. Therefore, it is an important region in which to address tectonic evolution processes of the Proto-Tethys Ocean and Gondwana. Here, we present petrology, zircon U-Pb, Sr-Nd-Hf isotope, and whole-rock geochemical data from newly recognized intermediate-mafic magmatic rocks from the Amdo microcontinent of central Tibet, with a view to gain insights into the nature and geotectonic evolution of the northern margin of Gondwana. Zircon grains from meta-andesites and metabasites in Amdo yielded magmatic crystallization ages of 490 Ma and 455-450 Ma, respectively. The meta- andesites are characterized by enrichment in large ion lithophile elements (e.g., Rb, Th, U, and K) and depletion in high field strength elements (e.g., Nb, Ta, and Ti) with positive zircon epsilon Hf(t) values (+3.4 to +6.4), which were probably derived from partial melting of a depleted mantle source enriched by minor fluids from subducted sediments in a continental arc setting. The metabasites are tholeiitic and exhibit both mid-ocean-ridge basalt (e.g., flat rare earth element patterns) and arc-like (e.g., elevated Th/Yb ratios) geo-chemical affinities, in combination with negative zircon epsilon Hf(t) (-4.6 to -0.3) and whole -rock epsilon Nd(t) (-0.21 to -0.45) values, suggesting that they were probably generated by vary-ing degrees of partial melting of a spinel peridotite source with similar to 5%-10% crustal assimilation in a back-arc setting. In this regard, we favor the interpretation that the Amdo microcontinent experienced long-lasting (ca. 530-450 Ma) subduction of the Proto-Tethys Ocean slab before the subsequent collisional accretion of microcontinents. Integrating results from previous studies, we propose that the Amdo microcontinent, South Qiangtang terrane, Qilian-Qaidam terrane, and other East Asian blocks were all located at the northern margin of East Gondwana, which recorded the arc-related magmatism along the proto-Tethyan margin in the early Paleo-zoic. The closure of the Proto-Tethys Ocean and initial collision along the East GondwanaProto-Tethyan margin may have been diachronous between ca. 455 and 430 Ma.
英文关键词	U-PB GEOCHRONOLOGY; HF ISOTOPIC COMPOSITIONS; NORTH LHASA TERRANE; ISLAND BASALTS OIB; GEOCHEMICAL EVIDENCE; TECTONIC EVOLUTION; CENTRAL QIANGTANG; ARC MAGMATISM; BAOSHAN BLOCK; NORTHEASTERN MARGIN
WOS研究方向	Geosciences, Multidisciplinary
WOS记录号	WOS:001133129700001
来源期刊	GEOLOGICAL SOCIETY OF AMERICA BULLETIN
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283781
作者单位	Ocean University of China; Ocean University of China; Laoshan Laboratory; Jilin University; Ministry of Natural Resources of the People's Republic of China; Hebei GEO University; Tianjin University
推荐引用方式 GB/T 7714	Peng, Yinbiao,Yu, Shengyao,Li, Sanzhong,et al. Diachronous subduction, closure of the Proto-Tethys Ocean, and collisional accretion of microcontinents: Insights from the early Paleozoic intermediate-mafic rocks in the Amdo microcontinent of the Tibetan Plateau[J],2023,135(11-12).
APA	Peng, Yinbiao.,Yu, Shengyao.,Li, Sanzhong.,Liu, Yongjiang.,Lv, Pei.,...&Ji, Wentao.(2023).Diachronous subduction, closure of the Proto-Tethys Ocean, and collisional accretion of microcontinents: Insights from the early Paleozoic intermediate-mafic rocks in the Amdo microcontinent of the Tibetan Plateau.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,135(11-12).
MLA	Peng, Yinbiao,et al."Diachronous subduction, closure of the Proto-Tethys Ocean, and collisional accretion of microcontinents: Insights from the early Paleozoic intermediate-mafic rocks in the Amdo microcontinent of the Tibetan Plateau".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 135.11-12(2023).