The geochemistry of Tibetan lavas: Spatial and temporal relationships, tectonic links and geodynamic implications

doi:10.1016/j.epsl.2019.04.032

IEECAS OpenIR > 古环境研究室

	The geochemistry of Tibetan lavas: Spatial and temporal relationships, tectonic links and geodynamic implications
	Yakovlev, Petr V.1,4; Saal, Alberto 2; Clark, Marin K.1; Hong, Chang 3; Niemi, Nathan A.1; Mallick, Soumen 2
通讯作者	Clark, Marin K.(marinkc@umich.edu)
	2019-08-15
发表期刊	EARTH AND PLANETARY SCIENCE LETTERS
ISSN	0012-821X
卷号	520 页码:115-126
摘要	The continental lithosphere is created and modified at convergent plate boundaries through complex, and interdependent, tectonic and magmatic processes. Evolution of the continental lithosphere modifies conditions within the mantle wedge, and therefore, the generation and composition of magmas at subduction zones. One approach to unraveling interactions between the continental lithosphere and asthenosphere in subduction zones is through the evolution of pre-, syn- and post-collisional mafic volcanism (i.e., MgO >= 6 wt%). Such lavas are most likely to contain characteristic geochemical fingerprints of the composition and physical condition of the mantle source at the time of melting. Here, we combine new analyses of thirty-one samples from the Hoh Xil Basin of the northern Tibetan Plateau with a compilation of published geochemical and geochronological data for late Mesozoic and Cenozoic magmas from the Indo-Eurasian collisional orogen. Geochronology of the Hoh Xil lavas reveals unrecognized early (similar to 27 Ma) alkali basaltic magmatism in northern Tibet that likely triggered melting of the mafic lower and metasedimentary upper continental crust, generating trachyanadesites-trachydacites and rhyolites, respectively. Based on a combined analysis of new and published compositional, age and spatial patterns of mafic lavas (MgO >= 6 wt%), we delineate two distinct periods of Tibetan mafic magmatism, with a major compositional change occurring at roughly 46 Ma. Early (pre-46 Ma) mafic lavas erupted only in central and southern Tibet, and were generated by melting within the mantle wedge during the northward subduction of the Neo-Tethyan oceanic slab. Late (post-46 Ma) mafic lavas were produced by the partial melting of metasomatized subcontinental lithospheric mantle. The latter group is spatially restricted to central Tibet between 46-30 Ma. After 30 Ma, lavas derived from melting of the lithospheric mantle expanded both northward and southward, eventually encompassing the entire Tibetan Plateau by 20 Ma. These observations suggest that melting of the lithospheric mantle beneath Tibet initiated earlier, and was more widespread, than previously thought. Our results also suggest that widespread melting of the mantle lithosphere across Tibet post-dates the cessation of upper crustal shortening in northern Tibet at similar to 30 Ma, and precedes the initiation of crustal extension at similar to 15-10 Ma. Hence, we suggest that plateau-wide melting of metasomatized subcontinental mantle lithosphere initiated following the collision of India with Eurasia, at similar to 46 Ma. This melting was induced by detachment of the Neo-Tethyan slab concomitant with thinning of the continental mantle lithosphere. Such melting has continued until the present, with the exception of volcanic quiescence in south-central Tibet since similar to 10 Ma. This quiescence likely arose from the underthrusting of Indian lithosphere beneath Eurasia. Although melting of the mantle lithosphere beneath Asia has previously been interpreted as an abrupt event, we propose that mantle lithosphere thinning and removal has been part of a continuum melting process during the Indo-Asian orogen that reflects an evolution from mantle wedge to mantle lithosphere melting accompanying the transition from subduction to collision. (C) 2019 Elsevier B.V. All rights reserved.
关键词	Indo-Asian orogen tectonics volcanics geochemistry mantle lithosphere continental collision
DOI	10.1016/j.epsl.2019.04.032
关键词[WOS]	SONGPAN-GANZI COMPLEX ; PLATEAU IMPLICATIONS ; CENOZOIC VOLCANISM ; CONSTRAINTS ; EVOLUTION ; MANTLE ; COLLISION ; LITHOSPHERE ; SUBDUCTION ; EXTENSION
收录类别	SCI ; SCI
语种	英语
资助项目	National Science Foundation (NSF)[EAR1032156] ; National Science Foundation (NSF)[EAR0929777] ; National Natural Science Foundation of China (NSFC)[40921120406] ; National Natural Science Foundation of China (NSFC)[41420104008]
WOS研究方向	Geochemistry & Geophysics
项目资助者	National Science Foundation (NSF) ; National Natural Science Foundation of China (NSFC)
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000474502200013
出版者	ELSEVIER SCIENCE BV
引用统计	被引频次：25[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.ieecas.cn/handle/361006/13703
专题	古环境研究室
通讯作者	Clark, Marin K.
作者单位	1.Univ Michigan, Dept Earth & Environm Sci, Ann Arbor, MI 48109 USA 2.Brown Univ, Dept Earth Environm & Planetary Sci, Providence, RI 02912 USA 3.Chinese Acad Sci, Inst Earth Environm, State Key Lab Loess & Quaternary Geol, Xian 710075, Shaanxi, Peoples R China 4.Montana Bur Mines & Geol, Butte, MT 59701 USA
推荐引用方式 GB/T 7714	Yakovlev, Petr V.,Saal, Alberto,Clark, Marin K.,et al. The geochemistry of Tibetan lavas: Spatial and temporal relationships, tectonic links and geodynamic implications[J]. EARTH AND PLANETARY SCIENCE LETTERS,2019,520:115-126.
APA	Yakovlev, Petr V.,Saal, Alberto,Clark, Marin K.,Hong, Chang,Niemi, Nathan A.,&Mallick, Soumen.(2019).The geochemistry of Tibetan lavas: Spatial and temporal relationships, tectonic links and geodynamic implications.EARTH AND PLANETARY SCIENCE LETTERS,520,115-126.
MLA	Yakovlev, Petr V.,et al."The geochemistry of Tibetan lavas: Spatial and temporal relationships, tectonic links and geodynamic implications".EARTH AND PLANETARY SCIENCE LETTERS 520(2019):115-126.