气候变化领域集成服务门户(CCPortal): Middle Triassic ultrapotassic rhyolites from the Tanggula Pass, southern Qiangtang, China: A previously unrecognized stage of silicic magmatism

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DOI	10.1016/j.lithos.2016.08.040
	Middle Triassic ultrapotassic rhyolites from the Tanggula Pass, southern Qiangtang, China: A previously unrecognized stage of silicic magmatism
	Chen, Sheng-Sheng; Shi, Ren-Deng; Fan, Wei-Ming; Zou, Hai-Bo; Liu, De-Liang; Huang, Qi-Shuai; Gong, Xiao-Han; Yi, Guo-Ding; Wu, Kang
通讯作者	Chen, SS (通讯作者)
发表日期	2016
ISSN	0024-4937
EISSN	1872-6143
起始页码	258
结束页码	276
卷号	264
英文摘要	There is a Mid-Late Mesozoic (Jurassic-Cretaceous) arc magmatic belt in southern Qiangtang subterrane associated with the north-dipping subduction of the Bangong-Nujiang Tethyan Ocean. Early Mesozoic (Triassic) magmatism, tectonic evolution of the southern Qjangtang subterrane, and the mechanism of its crustal growth, however, remain unclear. This paper reports zircon U-Pb age, whole-rock major, trace elemental, and Sr-Nd-Hf isotopic components for the Mesozoic Tanggula Pass rhyolites in southern Qiangtang subterrane. Our new data reveal a significant, previously unrecognized stage of magmatism in southern Qiangtang subterrane. The Tanggula Pass rhyolites are moderately-strongly peraluminous (A/CNK = 1.09-1.54), highly fractionated (SiO2 > 73%) and ultrapotassic (K2O/Na2O > 44%). Zircon U-Pb dating by LA-ICP-MS yields a concordant age with a weighted mean Pb-206/U-238 age of 235.9 +/- 0.86 Ma (n = 18, MSWD = 0.25). The large variations of major and trace element concentrations are mainly attributed to fractional crystallization of plagioclase, hornblende, Fe-Ti oxides, and accessory minerals such as apatite, allanite, monazite, and zircon in the shallow level. K-feldspar mainly occurs as cumulated mineral, resulting in high K2O contents and K2O/Na2O ratios. The rhyolites were derived by partial melting of mixed source rocks including older sedimentary rocks in the upper crust and juvenile materials, triggered by north-dipping subduction of the Bangong-Nujiang Tethyan oceanic lithosphere. The eruption age of Middle Triassic suggests that the initiation of northward subduction of the Bangong-Nujiang Tethyan ocean took place earlier than is currently assumed. Whole-rock Nd (ca. 155 to 234 Ga) and zircon Hf (ca. 1.77 to 2.33 Ga) data reflect the presence of the Proterozoic basement in the southern Qiangtang subterrane. Basaltic magma underplating and accretion of intra-oceanic arc complexes and oceanic plateau contributed to vertical crustal growth and lateral crustal growth, respectively. (C) 2016 Elsevier B.V. All rights reserved.
关键词	U-PB GEOCHRONOLOGY TRACE-ELEMENT COMPOSITION HF ISOTOPIC COMPOSITIONS NUJIANG SUTURE ZONE I-TYPE PLUTONISM VOLCANIC-ROCKS CALC-ALKALINE CENTRAL TIBET GRANITIC MAGMAS HIGH-POTASSIUM
英文关键词	Tibet; Bangong-Nujiang Tethys; Triassic; Ultrapotassic rhyolite; Crustal growth
语种	英语
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
WOS类目	Geochemistry & Geophysics ; Mineralogy
WOS记录号	WOS:000387191600019
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/258733
推荐引用方式 GB/T 7714	Chen, Sheng-Sheng,Shi, Ren-Deng,Fan, Wei-Ming,et al. Middle Triassic ultrapotassic rhyolites from the Tanggula Pass, southern Qiangtang, China: A previously unrecognized stage of silicic magmatism[J]. 中国科学院青藏高原研究所,2016,264.
APA	Chen, Sheng-Sheng.,Shi, Ren-Deng.,Fan, Wei-Ming.,Zou, Hai-Bo.,Liu, De-Liang.,...&Wu, Kang.(2016).Middle Triassic ultrapotassic rhyolites from the Tanggula Pass, southern Qiangtang, China: A previously unrecognized stage of silicic magmatism.LITHOS,264.
MLA	Chen, Sheng-Sheng,et al."Middle Triassic ultrapotassic rhyolites from the Tanggula Pass, southern Qiangtang, China: A previously unrecognized stage of silicic magmatism".LITHOS 264(2016).