Magma contamination of acidic rocks in Linxi area in southern Da Hinggan Mountains, northeast China

	Magma contamination of acidic rocks in Linxi area in southern Da Hinggan Mountains, northeast China
	Zhang, YB ; Sun, SH ; Hongma, H ; Mao, Q
刊名	ACTA PETROLOGICA SINICA
	2003-07-01
卷号	19 期号:3 页码:369-384
关键词	Da Hinggan petrigenesis contamination assimilation enclaves
ISSN号	1000-0569
文献子类	Article
英文摘要	The late Paleozoic (Rb-Sr, 275Ma, (Sr-87/Sr-86)(i) = 0. 70463) volcanic and pyroclastic sedimentary rocks that are dominated by submarine basalt and andesite are widely outcreped in Linxi area in the southern part of Dahinggan mountains. In the same area, the Mesozoic intrusive rocks and volcanic rocks also widely distributed there. In the margin of granite pluton, the rocks commonly transfer into adamellite and granodiotite gradually, and include plentiful enclaves dominated by mafic and intermediate rocks. The contact zone with wall rocks is a transitional metasomatic reaction zone, the boundary like a gulf shape is actually formed by magma eroding the wall rocks on the contact zone. Dacite, rachydacite with the acidity. lower than rhyolite also includes plentiful mafic-intermediate enclaves and closely co-exist with rhyolite. The chilled margins with plentiful acicular apatites are frequently observed in the contact zone surrounding those enclaves in the rocks. Most of the enclaves have various metasomatic reaction boundaries, and low grade metasomatic enclaves are similar to wall rocks in the features of texture and structure, minerals. The HFSE ratios (Nb/Ta, Zr/Hf) of the enclaves are close to the ones of late-Paleozoic volcanic rocks, and Sr isotope ratios data are scattered along the isochron of late-Paleozoic volcanic rocks. The content of the enclaves is related to position in the margin of a granite pluton and related to composition variation of adamellite, granodiorite and dacite, trachydacite. These evidences suggest that the enclaves, are the xenoliths actually from late-Paleozoic volcanic rocks, which were cool before they were captured by hot magma, and the acid rocks with low acidity had been added in the materials of late-Paleozoic volcanic rocks. There are two kinds of the kernel of zoning plagioclase in adamellite, granodiorite and dacite, trachydacite: one was rich in Ca and the other was low in Ca. But the compositions of outer zone of the zoning plagioclase only change into the same. The composition of highly metasomated. enclaves and the margin of granite pluton including those enclaves also change the same. Those composition variation trends recorded the assimilation process of two kinds of different materials. The petro-chemical features in Harker diagram and Nb/Ta (and Zr/Hf) VS SiO2 and Zr/Hf vs Nb/Ta reveal that the compositions of the acid rocks with low acidity of granite pluton or rhyolite lava flow have the mixing features of granite or rhyolite with late-Paleozoic volcanic rocks. These facts suggest that the low acidity rocks were produced while an acid magma contaminated by the materials from late-Paleozoic volcanic rocks. The mafic and intermediate volcanic rocks have been assimilated by metasomation on the basis of greenschist phase metamorphism.
WOS关键词	CRUSTAL CONTAMINATION ; GRANITOIDS ; VOLCANISM ; ORIGIN ; LAVAS ; EVOLUTION ; ENCLAVES ; MANTLE
WOS研究方向	Geology
语种	英语
出版者	SCIENCE CHINA PRESS
WOS记录号	WOS:000187675100001
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/78205]
专题	中国科学院地质与地球物理研究所
通讯作者	Zhang, YB
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Minerals & Resource, Beijing 100029, Peoples R China 2.China Univ Geosci, Fac Earth Sci, Wuhan 430074, Peoples R China
推荐引用方式 GB/T 7714	Zhang, YB,Sun, SH,Hongma, H,et al. Magma contamination of acidic rocks in Linxi area in southern Da Hinggan Mountains, northeast China[J]. ACTA PETROLOGICA SINICA,2003,19(3):369-384.
APA	Zhang, YB,Sun, SH,Hongma, H,&Mao, Q.(2003).Magma contamination of acidic rocks in Linxi area in southern Da Hinggan Mountains, northeast China.ACTA PETROLOGICA SINICA,19(3),369-384.
MLA	Zhang, YB,et al."Magma contamination of acidic rocks in Linxi area in southern Da Hinggan Mountains, northeast China".ACTA PETROLOGICA SINICA 19.3(2003):369-384.