气候变化领域集成服务门户(CCPortal): Shallow subduction of Indian slab and tectono-magmatic control on post-collisional porphyry mineralization in southeastern Tibet

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DOI	10.1016/j.oregeorev.2023.105360
	Shallow subduction of Indian slab and tectono-magmatic control on post-collisional porphyry mineralization in southeastern Tibet
	Zhou, Qiushi; Wang, Rui
发表日期	2023
ISSN	0169-1368
EISSN	1872-7360
卷号	155
英文摘要	The 1500-km long Gangdese belt in southern Tibet shows uneven distribution of giant to large porphyry deposits over 45 Mt Cu mainly in the middle-east segment between longitude 87-92 degrees E. However, the western (80-86 degrees E) and eastern end (92-96 degrees E) is generally barren. The recent discovery of Demingding, Cuibaizi and Tangbula porphyry deposits in the east of 92 degrees E has attracted great attention on their origin. Recent high-resolution seismic imaging shows the torn Indian lithosphere subducts with diverse angle. In contrast to the middle-east segment with moderate angle Indian plate subduction, the southeastern Tibet is characterized with a shallow dip of subduction (eastern of Comei rift), where Demingding, Cuibaizi and Tangbula deposits are located. To reveal the formation mechanism of these deposits as well as the Indian slab motion pattern beneath them, we compiled reported whole rock major and trace elements, Sr and Nd isotope signature, zircon trace element, U-Pb ages and Hf isotope data of Miocene ore-related adakitic rocks from Demingding and Tangbula to the north, and Oligocene ore-barren adakitic rocks from Linchi to the south. There is a clear negative correlation between zircon U-Pb ages of rocks and their distance to Indus-Yarlung Zangbo suture: Linchi is around 20 km away from the suture, with an average U-Pb age of 27.1 Ma, while Demingding and Tangbula rocks are 50 and 90 km away from the suture, with ages of 20.3 and 19.7 Ma respectively. Granitoids from Linchi have less compatible element Ni and Cr contents of 4.07 and 5.84 ppm on average respectively, while those of Demingding (20.1 and 43.4 ppm) and Tangbula (5.52 and 7.90 ppm) are much higher. Ni and Cr as compatible elements are concentrated in mafic minerals, and are thus proper indicators for mantle imprint indicators. In addition, as shown by Sr-Nd isotopes, Linchi granitoids have features of ancient crust [(87Sr/86Sr)i = 0.7059 to 0.7085, epsilon Nd(t) = -6.20 to-2.90], while Demingding and Tangbula granitoids show less radiogenic features [(87Sr/86Sr)i = 0.7059 to 0.7068, epsilon Nd(t) = -3.27 to-1.70], which are more similar to coexisting juvenile arc. Demingding and Tangbula gran-itoids also show signature of high fO2 and hydrous melt condition, as indicated by calculated fO2 of Delta FMQ + and amphibole fractionation indicated by decreasing Dy/Yb with SiO2, since amphibole favors MREE (Dy) rather than HREE (Yb). Combining above, our work shows that the Indian slab constantly subducted shallowly beneath these deposits, given no mantle-like signature of near-suture Oligocene adakitic rocks. We suggest the cause to the formation of Demingding, Tangbula and Cuibaizi deposits is the reactivation of pre-enriched arc root ma-terials, triggered by constant northward migration of Indian slab. This is supported by similar isotope signature between Miocene Demingding and Tangbula ore-related porphyries and coexisting arc, and absence of coeval pre-collisional porphyry deposits. The essential components for these porphyry deposits, high fO2 and water content, were also likely contributed from the pre-enriched juvenile arc root.
关键词	Gangdese Indian slab Geodynamic process Porphyry mineralization Adakitic rock
英文关键词	CONTINENTAL COLLISION ZONES; MAGMATIC WATER-CONTENT; EASTERN GANGDESE BELT; ZIRCON U-PB; CU-AU; SOUTHERN TIBET; LHASA TERRANE; ADAKITIC INTRUSIVES; STEEP SUBDUCTION; CRUST GROWTH
WOS研究方向	Geology ; Mineralogy ; Mining & Mineral Processing
WOS记录号	WOS:000953856500001
来源期刊	ORE GEOLOGY REVIEWS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283094
作者单位	China University of Geosciences - Beijing; China University of Geosciences - Beijing; China Geological Survey; Chinese Academy of Geological Sciences
推荐引用方式 GB/T 7714	Zhou, Qiushi,Wang, Rui. Shallow subduction of Indian slab and tectono-magmatic control on post-collisional porphyry mineralization in southeastern Tibet[J],2023,155.
APA	Zhou, Qiushi,&Wang, Rui.(2023).Shallow subduction of Indian slab and tectono-magmatic control on post-collisional porphyry mineralization in southeastern Tibet.ORE GEOLOGY REVIEWS,155.
MLA	Zhou, Qiushi,et al."Shallow subduction of Indian slab and tectono-magmatic control on post-collisional porphyry mineralization in southeastern Tibet".ORE GEOLOGY REVIEWS 155(2023).