Origin of the Gangdise (Transhimalaya) Permian arc in southern Tibet: Stratigraphic and volcanic geochemical constraints

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	Origin of the Gangdise (Transhimalaya) Permian arc in southern Tibet: Stratigraphic and volcanic geochemical constraints
	Geng, QR (Geng, Quan-Ru)6; Sun, ZM (Sun, Zhi-Ming); Pan, GT (Pan, Gui-Tang); Zhu, DC (Zhu, Di-Cheng); Wang, LQ (Wang, Li-Quan)
刊名	ISLAND ARC
	2009
卷号	18 期号:3 页码:467-487
关键词	Gangdise geochemistry island arc Paleotethys Permian stratigraphy Tibet volcanic rocks
ISSN号	1038-4871
英文摘要	The well-studied Mesozoic and Cenozoic volcanic rocks of the Gangdise Terrane, southern Tibet, are widely interpreted to have resulted from subduction of the Neotethys; however, Late Paleozoic volcanic rocks and their tectonic setting remain poorly studied. Based on new geological data, we carried out stratigraphical and geochemical analyses of Permian volcano-stratigraphic sequences within an east-west-trending, fault-bounded zone of uplift in the central Gangdise Terrane. Sedimentary rocks in this area consist of platform carbonates and terrigenous clastic rocks that represent widespread shallow-marine sedimentary basins developed around northern Gondwana. A regression or tectonic uplift event is recorded in Permian sedimentary rocks that show the local development of fluvial environments. The sedimentary succession contains evidence of two volcanic stages a period of basaltic extrusions and younger explosive felsic magmatism. The first volcanic stage is Early and Middle Permian in age. Tholeiitic basaltic lavas are exposed around Maizhokunggar (Tangjia) and Lhunzhub in central Gangdise. The Lower Permian basalts are relatively enriched in MgO (4.58-12.19%), whereas the Middle Permian basalts are characterized by high Al(2)O(3) contents (11.75-21.22%). Rocks of both ages are enriched in large-ion lithophile elements (LILE) and light rare earth elements (LREE), and show pronounced negative Nb and Ta anomalies. Total REE contents and light (LREE)/heavy (HREE) ratios increased from the Early to Middle Permian. Observed variations in initial Sr, Nd, and Pb isotopes ((87)Sr/(86)Sr(i) = 0.7013-0.7066, (207)Pb/(204)Pb(i) = 15.53-15.63, and (208)Pb/(204)Pb(i) = 38.04-38.64 for a given (206)Pb/(204)Pb(i); epsilon Nd = +0.69 to -11.55) can be explained by crustal interaction with mantle sources, as is characteristic of metasomatism by slab-derived fluids or assimilation and fractional crystallization (AFC) processes during magmatic evolution. The observed geochemical signatures, coupled with stratigraphic constraints, support the hypothesis that an initial arc formed during the Permian due to southward subduction of the Paleotethys, predating the well-known Mesozoic arc preserved in the Gangdise Terrane.
学科主题	火成岩岩石学
WOS关键词	OCEAN MANTLE DOMAIN ; INDIAN-OCEAN ; ISLAND-ARC ; BREAK-UP ; BASALTS ; MAGMATISM ; EVOLUTION ; CRUST ; PRODUCTS ; GANGDESE
WOS研究方向	Geology
语种	英语
出版者	WILEY-BLACKWELL PUBLISHING, INC
WOS记录号	WOS:000269057400005
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38843]
专题	中国地质调查局
作者单位	1.[Geng, Quan-Ru 2.Sun, Zhi-Ming 3.Pan, Gui-Tang 4.Zhu, Di-Cheng 5.Chengdu Inst Geol & Mineral Resources, Chengdu 610082, Peoples R China 6.中国地质调查局成都地质调查中心
推荐引用方式 GB/T 7714	Geng, QR ,Sun, ZM ,Pan, GT ,et al. Origin of the Gangdise (Transhimalaya) Permian arc in southern Tibet: Stratigraphic and volcanic geochemical constraints[J]. ISLAND ARC,2009,18(3):467-487.
APA	Geng, QR ,Sun, ZM ,Pan, GT ,Zhu, DC ,&Wang, LQ .(2009).Origin of the Gangdise (Transhimalaya) Permian arc in southern Tibet: Stratigraphic and volcanic geochemical constraints.ISLAND ARC,18(3),467-487.
MLA	Geng, QR ,et al."Origin of the Gangdise (Transhimalaya) Permian arc in southern Tibet: Stratigraphic and volcanic geochemical constraints".ISLAND ARC 18.3(2009):467-487.