气候变化领域集成服务门户(CCPortal): Identification of recycled oceanic crust in the mantle source of sulfide-bearing lower crust of the Gangdese magmatic arc, Southern Tibet: Constraints from Sr-Nd-Li isotopes

CCPortal

DOI	10.1016/j.oregeorev.2023.105684
	Identification of recycled oceanic crust in the mantle source of sulfide-bearing lower crust of the Gangdese magmatic arc, Southern Tibet: Constraints from Sr-Nd-Li isotopes
	Wang, Ling; Tian, Shihong; Hou, Zengqian; Yang, Zhiming; Zhong, Fujun; Yang, Zhusen; Li, Xianfang
发表日期	2023
ISSN	0169-1368
EISSN	1872-7360
卷号	162
英文摘要	Post-collisional porphyry copper deposit (PCD) is a new genetic type of PCDs discovered in the Himalayan-Tibetan orogenic belt. It is believed that the formation of ore-forming magmas results from the re-melting of a sulfide-bearing, thickened, juvenile mafic lower crust in a magmatic arc associated with the oceanic plate subduction. However, the material contribution of subduction processes to the formation of this particular arc magma remains unclear. In this paper, we attempted to present a study that includes petrology, mineral geochemistry, whole rock Sr-Nd-Li isotopes, of Late Cretaceous Lilong ultramafic igneous rocks, south Lhasa sub-terrane, Tibet. The target ultramafic igneous rocks are sulfide-bearing cumulates. They show relative depletion in whole rock Nd isotopic compositions, slightly elevated (87Sr/86Sr)i ratios (0.7043-0.7059), and variable 87Li values (2.8-9.0 parts per thousand). Simulation results showed that trace element of melts in equilibrium with cumulus hornblende grains exhibit typical arc-like trace element distribution patterns, indicating that these ultramafic igneous rocks crystallized from arc magma. Additionally, the modeled melts showed enrichment in melt-mobile elements such as Ba, Pb, Sr, Th, and light rare earth elements (LREE), and higher Th/Yb ratios, as compared with normal mid-ocean ridge basalt (MORB). These geochemical properties can be explained by the metasomatism of depleted MORB mantle peridotites by hydrous melts derived from subducted seafloor sediments. Whole rock Sr isotopes show correlations with Ba/Nb and Th/La ratios for the modeled melts, showing that fluids from the basaltic igneous crust, in addition to hydrous melts from the seafloor sediments, contribute to their mantle source. In addition, the heterogeneity of whole rock 87Li values for ultramafic igneous rocks also indicates that their mantle sources have been metasomatized by terrigenous sediment-and altered oceanic crust-derived fluids. Depleted MORB mantle peridotites react with the mixed fluids at sub-arc depths to produce ultramafic metasomatites, and model calculations for trace element contents and Sr-Nd-Li isotopic compositions further validate that the geochemical compositions of the Lilong ultramafic rocks can be clarified by this process. The results show that the deeply subducted oceanic crust may have played an important role in the formation of sulfide-bearing juvenile mafic lower crust of this magmatic arc.
关键词	Arc magma Sulfide-bearing cumulates Li isotopes Fluid metasomatism Porphyry copper deposit
英文关键词	ZIRCON U-PB; PORPHYRY CU DEPOSITS; SLAB ROLL-BACK; ADAKITIC AFFINITIES; OROGENIC ECLOGITES; SEDIMENTARY INPUT; CONTINENTAL-CRUST; VOLCANIC-ROCKS; MILIN AREA; LITHIUM
WOS研究方向	Geology ; Mineralogy ; Mining & Mineral Processing
WOS记录号	WOS:001084775600001
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/283411
作者单位	East China University of Technology; China Geological Survey; Chinese Academy of Geological Sciences; China Geological Survey; Chinese Academy of Geological Sciences; Institute of Geology, Chinese Academy of Geological Sciences
推荐引用方式 GB/T 7714	Wang, Ling,Tian, Shihong,Hou, Zengqian,et al. Identification of recycled oceanic crust in the mantle source of sulfide-bearing lower crust of the Gangdese magmatic arc, Southern Tibet: Constraints from Sr-Nd-Li isotopes[J],2023,162.
APA	Wang, Ling.,Tian, Shihong.,Hou, Zengqian.,Yang, Zhiming.,Zhong, Fujun.,...&Li, Xianfang.(2023).Identification of recycled oceanic crust in the mantle source of sulfide-bearing lower crust of the Gangdese magmatic arc, Southern Tibet: Constraints from Sr-Nd-Li isotopes.ORE GEOLOGY REVIEWS,162.
MLA	Wang, Ling,et al."Identification of recycled oceanic crust in the mantle source of sulfide-bearing lower crust of the Gangdese magmatic arc, Southern Tibet: Constraints from Sr-Nd-Li isotopes".ORE GEOLOGY REVIEWS 162(2023).