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	Petrogenesis of miocene volcanic rocks in the sailipu area, western tibetan plateau: geochemical and sr-nd isotopic constraints
	Wang BaoDi1,2,3; Xu JiFeng1; Zhang XingGuo2; Chen JianLin1,3; Kang ZhiQiang1,3; Dong YanHui1,3
刊名	Acta petrologica sinica
	2008-02-01
卷号	24期号:2页码:265-278
关键词	Ultrapotassic and potassic rocks Adakitic rocks Lithospheric mantle Slab break-off Sailipu area Tibetan plateau
ISSN号	1000-0569
通讯作者	Wang baodi(baodiwang@gig.ac.cn)
英文摘要	Cenozoic volcanic rocks distributed in the sailipi area of the western lhasa block in the tibetan plateau are divided into ultrapotassic, potassic and calc-alkaline series according to the content of major element composition. the main rock types are trachyandesite and trachyte. ar-40-ar-39 dating results show these rocks were erupted at approximate to 17. 58ma, confirming that volcanism occurred in the miocene. ultrapotassic, potassic, and clay alikaline volcanic rocks are characterized by enrichment in lbee and large ion lithophile elements ( lile), such as rh, ba, th and depletion in high field strength elements ( hfse), such as nb, ta, ti. the ultrapotassic volcanic rocks show relatively high k2o (6.3% similar to 8.55%), mgo (6. 75% similar to 8. 96%), cr (270. 7 x 10(-6) similar to 460.4 x 10(-6)), ni (142. 3 x 10(-6) - 233. 9 x 10(-6)), high initial sr-87/sr-86 (0.71883 similar to 0.72732) and low epsilon(nd) (-14. 78 similar to - 15. 37). these geochemical and isotopic characteristics indicate that the ultrapotassic volcanic rocks were probably derived from a previously depleted harzburgite mantle source then potassium enrichment by metasomatism during early subduction events. potassic volcanic rocks have lower k2o, mgo, cr, ni and higher ba, sr content than the ultrapotassic volcanic rocks, they show high initial sr-87/sr-86 (0.71553 similar to 0.71628), nd-143/nd-144(0. 51197 similar to 0. 51198), and spatially coexist with ultrapotassic volcanic rocks. these rocks were most likely differentiation products of the ultraptassic magmas. similar to typical adakites in geochemistry, the clay alikaline volcanic rocks are characteristic of high sr contents( 881.7 x 10(-6) similar to 1309.2 x 10(-6)), sr/y ( 50 similar to 108) ratios, depletion of y and yb, no eu anomaly and positive sr anomalies, meanwhile these rocks show relatively higher k, 0, mgo, lower initial sr-87/sr-86(0.70928 similar to 0.71374) and higher, em, (-7. 90 similar to -10. 91) than the ultrapotassic volcanic rocks. based on the chemical features mentioned above, we suggest that adakitic clac-alikaline volcanic magmas were generated by partial melting of the relatively k-rich mafic lower crust beneath lhasa block. it is in this region that ultrapotassic and potassic volcanic rocks in the lhasa block coexist with the n-s rifts on both space and time, therefore we conclude that the formation of the miocene potassic-ultrapotassic volcanic rocks and n-s rift systems in the lhasa block were probably triggered by slab break-off of the india continent lithosphere.
WOS关键词	ULTRAPOTASSIC ROCKS ; SOUTHERN TIBET ; LHASA BLOCK ; POSTCOLLISIONAL MAGMATISM ; CONTINENTAL COLLISION ; POTASSIC ROCKS ; ORIGIN ; SUBDUCTION ; EXTENSION ; GENESIS
WOS研究方向	Geology
WOS类目	Geology
语种	英语
出版者	SCIENCE CHINA PRESS
WOS记录号	WOS:000259117600007
内容类型	期刊论文
URI标识	http://www.corc.org.cn/handle/1471x/2384966
专题	中国科学院大学
通讯作者	Wang BaoDi
作者单位	1.Chinese Acad Sci, Guanzhou Inst Geochem, Key Lab Geochronol & Geochem, Guangzhou 510640, Guangdong, Peoples R China 2.Reg Geol Surveying Party Tibet Bur Geol & Explora, Lhasa 851400, Peoples R China 3.Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China
推荐引用方式 GB/T 7714	Wang BaoDi,Xu JiFeng,Zhang XingGuo,et al. Petrogenesis of miocene volcanic rocks in the sailipu area, western tibetan plateau: geochemical and sr-nd isotopic constraints[J]. Acta petrologica sinica,2008,24(2):265-278.
APA	Wang BaoDi,Xu JiFeng,Zhang XingGuo,Chen JianLin,Kang ZhiQiang,&Dong YanHui.(2008).Petrogenesis of miocene volcanic rocks in the sailipu area, western tibetan plateau: geochemical and sr-nd isotopic constraints.Acta petrologica sinica,24(2),265-278.
MLA	Wang BaoDi,et al."Petrogenesis of miocene volcanic rocks in the sailipu area, western tibetan plateau: geochemical and sr-nd isotopic constraints".Acta petrologica sinica 24.2(2008):265-278.

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