Relationships between basic and silicic magmatism in continental rift;settings: A petrogeochemical study of carboniferous post-collisional;rift silicic volcanics in Tianshan, NW China

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	Relationships between basic and silicic magmatism in continental rift;settings: A petrogeochemical study of carboniferous post-collisional;rift silicic volcanics in Tianshan, NW China
	Xia, LQ; Xia, ZC; Xu, XY; Li, XM; Ma, ZP; Wang, LS
刊名	ACTA GEOLOGICA SINICA-ENGLISH EDITION
	2005
卷号	79 期号:5 页码:633-653
关键词	Carboniferous rift-related silicic volcanic rocks geochemistry bimodal volcanism Tianshan NW China
ISSN号	1000-9515
英文摘要	Petrogeochemical data are reported for silicic volcanic rocks from the Tianshan Carboniferous rift, with the aim of discussing the petrogenesis of silicic magmas. Incompatible element vs. incompatible element diagrams display smooth positive trends for the Tianshan Carboniferous rift-related volcanic rocks; the isotope ratios of the silicic lavas [Sr-87/Sr-86((t))=0.69988-0.70532; epsilon(Nd(t))=4.76-8.00; Pb-206/Pb-204((t))=17.435-18.017; Pb-207/Pb-204((t))=15.438-15.509; Pb-208/Pb-204((t))=37.075-37.723] encompass those of the basic lavas. These data suggest a genetic link between rhyolites and basalts, but are not definitive in establishing whether silicic rocks are related to basalts through fractional crystallization or partial melting. Geochemical modeling of incompatible vs. compatible elements excludes the possibility that silicic melts are generated by the melting of basaltic rocks, and indicates a derivation by fractional crystallization plus moderate assimilation of wall rocks (AFC) starting from intermediate rocks to silicic rocks. Continuous AFC from basalt to rhyolite, with small rates of crustal assimilation, best explains the geochemical data. The presence or absence of bimodal volcanism (the "Daly Gap") might be related to cooling rates of magma chambers. In central and eastern Tianshan, the crust was thinner and the cooling rates of the magma chamber within the crust were greater. These conditions resulted in a rapid fall in temperature within the magma reservoir and caused a narrow temperature interval over which intermediate melts formed, effectively reducing the volume of the intermediate melts.
学科主题	火成岩岩石学
WOS研究方向	Geology
语种	英语
出版者	GEOLOGICAL SOC CHINA
WOS记录号	WOS:000232988300006
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/37878]
专题	中国地质调查局西安地质调查中心
作者单位	Xian Inst Geol & Mineral Resources, China Geol Survey, Xian 710054, Shaanxi, Peoples R China.
推荐引用方式 GB/T 7714	Xia, LQ,Xia, ZC,Xu, XY,et al. Relationships between basic and silicic magmatism in continental rift;settings: A petrogeochemical study of carboniferous post-collisional;rift silicic volcanics in Tianshan, NW China[J]. ACTA GEOLOGICA SINICA-ENGLISH EDITION,2005,79(5):633-653.
APA	Xia, LQ,Xia, ZC,Xu, XY,Li, XM,Ma, ZP,&Wang, LS.(2005).Relationships between basic and silicic magmatism in continental rift;settings: A petrogeochemical study of carboniferous post-collisional;rift silicic volcanics in Tianshan, NW China.ACTA GEOLOGICA SINICA-ENGLISH EDITION,79(5),633-653.
MLA	Xia, LQ,et al."Relationships between basic and silicic magmatism in continental rift;settings: A petrogeochemical study of carboniferous post-collisional;rift silicic volcanics in Tianshan, NW China".ACTA GEOLOGICA SINICA-ENGLISH EDITION 79.5(2005):633-653.