Mineral chemistry and crystallization conditions of the Late Cretaceous   Mamba pluton from the eastern Gangdese, Southern Tibetan Plateau

doi:10.1007/s12583-016-0713-5

CORC > 北京大学 > 地球与空间科学学院

	Mineral chemistry and crystallization conditions of the Late Cretaceous Mamba pluton from the eastern Gangdese, Southern Tibetan Plateau
	Li, Xiaowei ; Mo, Xuanxue ; Scheltens, Mark ; Guan, Qi
刊名	JOURNAL OF EARTH SCIENCE
	2016
关键词	Mamba pluton Gangdese terrane MMEs K-feldspar megacrysts magma mixing P-T conditions oxygen fugacity in-situ trace element MAFIC MICROGRANULAR ENCLAVES K-FELDSPAR MEGACRYSTS ZIRCON U-PB TECTONIC EVOLUTION ALKALI FELDSPAR TRACE-ELEMENT HORNBLENDE THERMOBAROMETRY SUBVOLCANIC ROCKS RIDGE SUBDUCTION GRANITIC-ROCKS
DOI	10.1007/s12583-016-0713-5
英文摘要	The Late Cretaceous Mamba granodiorite belongs to a part of the Mesozoic Gangdese continental magmatic belt. No quantitative mineralogical study has been made hitherto, and hence the depth at which it formed is poorly constrained. Here we present mineralogical data for the Mamba pluton, including host rocks and their mafic microgranular enclaves (MMEs), to provide insights into their overall crystallization conditions and information about magma mixing. All amphiboles in the Mamba pluton are calcic, with (B)(Ca+Na)> 1.5, and Si=6.81-7.42 apfu for the host rocks and Si=6.77-7.35 apfu for the MMEs. The paramount cation substitutions in amphibole include edenite type and tschermakite type. Biotites both in the host rocks and the MMEs collectively have high MgO (13.19 wt.%-13.03 wt.%) contents, but define a narrow range of Al apfu (atoms per formula unit) variations (2.44-2.57). The oxygen fugacity estimates are based on the biotite compositions cluster around the NNO buffer. The calculated pressure ranges from 1.2 to 2.1 kbar according to the aluminum-in-hornblende barometer. The computed pressure varies from 0.9 to 1.3 kbar based on the aluminum-in-biotite barometer which corresponds to an average depth of ca. 3.9 km. Besides, the estimates of crystallization pressures vary from 0.8 to 1.4 kbar based on the amphibole barometer proposed by Ridolfi et al. (2010), which can be equivalent to the depths ranging from 3.1 to 5.2 km. The MMEs have plagioclase oscillatory zonings and quartz aggregates, probably indicating the presence of magma mixing. Besides, core-to-rim element variations (Rb, Sr, Ba, and P) for the K-feldspar megacrysts serve as robust evidence to support magma mixing and crystal fractionation. This indicates the significance of the magma mixing that contributes to the formation of K-feldspar megacryst zonings in the Mamba pluton.; We greatly appreciate comments provided by reviewers of the early versions of this manuscript, as well as the kind help of the editors. This study was jointly funded by the National Natural Science Foundation of China; the China Postdoctoral Science Foundation; China University of Geosciences; the Fundamental Research Funds for the Central Universities of China (No.2652015018). We appreciate Guiming Shu, Tingting Shen, Yi Sun and Xiangkun Ge for their kind assistance with elemental analyses. We also thank Zhidan Zhao, Dicheng Zhu, Feng Yu, Min Liu, Wenting Zhao, Liangliang Zhang and Yu Hu; SCI(E); 中国科学引文数据库(CSCD); ARTICLE; vividlixiaowei@163.com; moxx@cugb.edu.cn; 4; 545-570; 27
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/491747]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Li, Xiaowei,Mo, Xuanxue,Scheltens, Mark,et al. Mineral chemistry and crystallization conditions of the Late Cretaceous Mamba pluton from the eastern Gangdese, Southern Tibetan Plateau[J]. JOURNAL OF EARTH SCIENCE,2016.
APA	Li, Xiaowei,Mo, Xuanxue,Scheltens, Mark,&Guan, Qi.(2016).Mineral chemistry and crystallization conditions of the Late Cretaceous Mamba pluton from the eastern Gangdese, Southern Tibetan Plateau.JOURNAL OF EARTH SCIENCE.
MLA	Li, Xiaowei,et al."Mineral chemistry and crystallization conditions of the Late Cretaceous Mamba pluton from the eastern Gangdese, Southern Tibetan Plateau".JOURNAL OF EARTH SCIENCE (2016).