Identification and petrogenesis of potassic volcanic rocks with "ultrapotassic" characteristics from Maqiang area in Lhasa block.

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	Identification and petrogenesis of potassic volcanic rocks with "ultrapotassic" characteristics from Maqiang area in Lhasa block.
	Wang, BD (Wang BaoDi); Chen, LK (Chen LingKang); Xu, JF (Xu JiFeng); Liu, HF (Liu HongFei); Chen, JL (Chen JianLin); Kang, ZQ (Kang ZhiQiang)
刊名	ACTA PETROLOGICA SINICA
	2011
卷号	27 期号:6 页码:1662-1674
关键词	Potassic-ultrapotassic volcanic rocks Post-collisional magmatism Temporal distribution Maqiang area Lhasa block
ISSN号	1000-0569
英文摘要	It is generally accepted that the post-collisional potassic and ultrapotassic magmatism are erupted from western to eastern in temporal in Lhasa block of Tibetan Plateau. However, this study has identified the potassic volcanic rocks from the Maqiang area in central of Lhasa block, which formed at similar to 21.3Ma by (40)Ar-(39)Ar dating. These potassic rocks are geochemical similar to ultrapotassic rocks, e. g., high in MgO (> 3%) and K(2)O/Na(2)O (K(2)O/Na(2)O > 2). The high MgO contents of potassic rocks in studying area caused for late-altered dolomite and they are more similar to potassic volcanic rocks although they show some "ultrapotassic" characteristics. Geochemically and tectonically, these potassic rocks in studying area are similar to the potassic-ultrapotassic rocks occurring along N-S rifts in the western Lhasa block. The enrichment in light rare earth elements (LREE), large ion lithophile elements (LILE, e. g., Rb, Ba and Th) and depletion in HFSE (e. g., Nb, Ta and Ti), and high initial (87)Sr/(86)Sr and low epsilon(Nd)(t) values of the potassic rocks in studying area, indicated that they were probably generated by partial melting of a metasomatic enrichment mantle related to early subduction events. Recognition of the potassic rocks in the Maqiang area imply that post-collisional potassic-ultrapotassic magmtism did not migrate from west to east in the Lhasa block. In other words, the post-collisional potassic and ultrapotassic lava in the Lhasa block were might erupted at the same time. And we suggest that the formation of the Miocene potassic-ultrapotassic volcanic rocks and N-S rifts in the Lhasa block were probably triggered by slab break-off of the India continent lithosphere during northern intra-continent subduction in early Miocene.
学科主题	火成岩岩石学
WOS关键词	MANTLE SOURCE CHARACTERISTICS ; WESTERN TIBETAN PLATEAU ; SOUTHERN TIBET ; ISOTOPIC COMPOSITIONS ; SUBDUCTED SEDIMENTS ; SW TIBET ; CONSTRAINTS ; MAGMATISM ; PB ; EVOLUTION
WOS研究方向	Geology
语种	中文
出版者	SCIENCE PRESS
WOS记录号	WOS:000292995600008
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39271]
专题	中国地质调查局
作者单位	Inst Geol Survey Tibet Autonomous Reg, Lhasa 850000, Peoples R China
推荐引用方式 GB/T 7714	Wang, BD ,Chen, LK ,Xu, JF ,et al. Identification and petrogenesis of potassic volcanic rocks with "ultrapotassic" characteristics from Maqiang area in Lhasa block.[J]. ACTA PETROLOGICA SINICA,2011,27(6):1662-1674.
APA	Wang, BD ,Chen, LK ,Xu, JF ,Liu, HF ,Chen, JL ,&Kang, ZQ .(2011).Identification and petrogenesis of potassic volcanic rocks with "ultrapotassic" characteristics from Maqiang area in Lhasa block..ACTA PETROLOGICA SINICA,27(6),1662-1674.
MLA	Wang, BD ,et al."Identification and petrogenesis of potassic volcanic rocks with "ultrapotassic" characteristics from Maqiang area in Lhasa block.".ACTA PETROLOGICA SINICA 27.6(2011):1662-1674.