Genetic mineralogy and metamorphic evolution of Al-rich gneisses in the;Shiguai area, Daqingshan-Wulashan metamorphic complex belt

	Genetic mineralogy and metamorphic evolution of Al-rich gneisses in the;Shiguai area, Daqingshan-Wulashan metamorphic complex belt
	Cai Jia 2; Liu PingHua ; Liu FuLai ; Liu JianHui ; Wang Fang ; Shi JianRong
刊名	ACTA PETROLOGICA SINICA
	2013
卷号	29 期号:2 页码:437-461
关键词	Al-rich gneisses Metamorphic P-T path Khondalite belt Shiguai area Daqingshan
ISSN号	1000-0569
英文摘要	Al-rich gneisses as interlayers within mafic granulites are widespread in the Shiguai area, Daqingshan-Wulashan metamorphic complex belt which is belong to the central part of the Khondalite Belt of the North China Craton. Shiguai Al-rich gneisses consist mainly of sillimanite-garnet-cordierite gneiss, hypersthene-garnet gneiss and sillimanite-garnet gneiss. Based on integrated structural, petrographic, mineral compositional features, geothermobarometric estimations and P-T pseudosection modelling in the system NCKFMASHTO, the metamorphic evolution for the Shiguai Al-rich gneisses could be subdivided into four metamorphic stages. Thereinto, early prograde metamorphic stage (M-1) is characterized by garnet cores and the mineral inclusions of biotite + quartz + plagioclase +/- sillimanite +/- K-feldspar +/- spinel. In contrast, mineral assemblage at the peak metamorphic stage (M-2) is interpreted to be matrix garnet and coarse-grained sillimanite + biotite + quartz + plagioclase + K-feldspar +/- magnetite +/- ilmenite, which formed at P-T conditions of 840 similar to 860 degrees C and 10.0 similar to 10.5kbar. Typical decompressional reactions, such as Grt + Sil + Qz -> Crd,Grt + Melt -> Crd + Bt + Pl and Grt + Melt -> Crd + Qz +/- Pl have been identified at the post-peak metamorphic stage (M-3), and new mineral assemblage of garnet + cordierite + biotite + plagioclase + quartz sillimanite +/- hypersthene was formed at this stage with P-T conditions of 720 similar to 800 degrees C and 5.6 similar to 6.1 kbar. The late cooling stage (M-4) is characterized by a retrogressive mineral assemblage of garnet + biotite + plagioclase + quartz + magnetite +/- K-feldspar +/- ilmenite, which formed at P - T conditions of 616 similar to 661 degrees C and 3.4 similar to 5.2kbar. This indicates that the Shiguai Al-rich gneisses recorded a clockwise near-isothermal decompression (ITD) P-T path following by a near-isobaric cooling (IBC) stage. It can be concluded that the Shiguai Al-rich gneisses within the Daqingshan-Wulashan metamorphic complex belt was indeed involved in the subduction-collision orogenic event between Yinshan block and Ordos block at Pakoproterozoic.
学科主题	变质岩岩石学
WOS关键词	NORTH CHINA CRATON ; ULTRAHIGH-TEMPERATURE METAMORPHISM ; ROCK-FORMING ; MINERALS ; PB ZIRCON AGES ; KHONDALITE BELT ; U-PB ; GRANULITE-FACIES ; INNER-MONGOLIA ; ORTHO-PYROXENE ; WESTERN BLOCK
WOS研究方向	Geology
语种	中文
出版者	SCIENCE PRESS
WOS记录号	WOS:000317531300008
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/40064]
专题	中国地质科学院地质研究所
作者单位	1.Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China. 2.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Cai Jia,Liu PingHua,Liu FuLai,et al. Genetic mineralogy and metamorphic evolution of Al-rich gneisses in the;Shiguai area, Daqingshan-Wulashan metamorphic complex belt[J]. ACTA PETROLOGICA SINICA,2013,29(2):437-461.
APA	Cai Jia,Liu PingHua,Liu FuLai,Liu JianHui,Wang Fang,&Shi JianRong.(2013).Genetic mineralogy and metamorphic evolution of Al-rich gneisses in the;Shiguai area, Daqingshan-Wulashan metamorphic complex belt.ACTA PETROLOGICA SINICA,29(2),437-461.
MLA	Cai Jia,et al."Genetic mineralogy and metamorphic evolution of Al-rich gneisses in the;Shiguai area, Daqingshan-Wulashan metamorphic complex belt".ACTA PETROLOGICA SINICA 29.2(2013):437-461.