成果归属作者：

莫宣学 ; 董国臣 ; 罗照华 ; 赵志丹 ; 周肃 ; 朱弟成

成果归属机构：

地球科学与资源学院

作者：

Zhao, Zhidan ; Mo, Xuanxue ; Dilek, Yildirim ; Niu, Yaoling ; DePaolo, Don J. ; Robinson, Paul ; Zhu, Dicheng ; Sun, Chenguang ; Dong, Guochen ; Zhou, Su ; Luo, Zhaohua ; Hou, Zengqian

单位：

China Univ Geosci, Sch Earth Sci & Mineral Resources, Div Petrol & Mineral, Beijing 100083, Peoples R China;China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China;Miami Univ, Dept Geol, Oxford, OH 45056 USA;Univ Durham, Dept Earth Sci, Durham DH1 3LE, England;Univ Calif Berkeley, Ctr Isotope Geochem, Berkeley, CA 94720 USA;Dalhousie Univ, Dept Earth Sci, Halifax, NS B3H 4J1, Canada;Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China

关键词：

Tibetan plateau; Sr-Nd-Pb-O isotopes; Ultrapotassic rocks; India continental subduction

摘要：

Ultrapotassic lavas having distinct geochemical compositions (K2O/Na2O >2, K2O >3%, and MgO >3%) are common and widespread on the Tibet Plateau, where they are closely linked to N-S-trending normal faults. The Tibetan ultrapotassic rocks range in age from -8 to 24 Ma, slightly older than the spatially associated potassic rocks (10-22 Ma). These lavas consist mainly of trachyte, trachyandesite, basaltic trachyandesite, phonolite and tephriphonolite. They have high light rare earth element (LREE) and large ion lithophile element (LILE) concentrations, but are low in high field strength elements (HFSE). They are characterized by having extremely radiogenic Sr (Sr-87/Sr-86((i))=0.710719 to 0.736451) and Pb isotopes (Pb-206/Pb-204 = 18.449-19.345, Pb-207/Pb-204 = 15.717-15.803, Pb-208/Pb-204=39.443-40.168) with unradiogenic Nd isotopes (epsilon(Nd(O)) = -7.6 to -15) and old Nd model ages (T-DM = 1.3-2.1 Ga), similar in character to the Himalaya crystalline basement. Their isotopic character is interpreted to reflect subduction of the Indian plate beneath the Lhasa terrane, leading to a highly contaminated mantle source. Delamination of the subducted oceanic/continental materials may have played an essential role in the genesis of the ultrapotassic rocks in the Lhasa terrane. The available geological, geochemical and geophysical data favor a model in which the Indian plate was subducted under southern Tibet. (C) 2009 Elsevier B.V. All rights reserved.

基金：

National Key Project for Basic Research [2009CB421002, 2002CB412600]; NSF of China [40873023, 40830317, 40473020, 40672044, 40503005, 40572048]; 111 project [B07011]; China Geological Survey and China Scholarship Council; NSERC

语种：

英文

DOI：

10.1016/j.lithos.2009.02.004

来源：

LITHOS,2009(1-2):190-212.

出版日期：

2009-11

提交日期：

2017-12-14

引用参考：

Zhao, Zhidan; Mo, Xuanxue; Dilek, Yildirim; Niu, Yaoling; DePaolo, Don J.; Robinson, Paul; Zhu, Dicheng; Sun, Chenguang; Dong, Guochen; Zhou, Su; Luo, Zhaohua; Hou, Zengqian. Geochemical and Sr-Nd-Pb-O isotopic compositions of the post-collisional ultrapotassic magmatism in SW Tibet: Petrogenesis and implications for India intra-continental subduction beneath southern Tibet[J]. LITHOS,2009(1-2):190-212.