The fragment of Paleo-Tethys ophiolite from central Qiangtang, Tibet:Geochemical evidence of meta-basites in Guoganjianian  

作　　者：ZHAI QingGuo1,2, LI Cai2 & HUANG XiaoPeng2 1 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China 2 College of Earth Sciences, Jilin University, Changchun 130061, China 

出　　处：《Science China Earth Sciences》2007年第9期1302-1309,共8页中国科学（地球科学英文版）

基　　金：Supported by China Geological Survey (Grant Nos. 200313000054,20031300015 and 1212010561605)

摘　　要：N-MORB-type metabasites are discovered in the Guoganjianian area, central Qiangtang, Tibet, which are mainly metagabbro with cumulate structure and metabasalt. The rocks are distributed nearly from west to east unconformably underlying the Wanghuling Group of upper Triassic. On the basis of geo- chemical analysis, we find that the content of SiO2 is 43.03%―53.42%, and TiO2 1%―2.67%, Al2O3 16.75%―21.52%, CaO 7.03%―11.13%, K2O 0.05%―0.38%; the REE pattern is slight depletion or flat, and the trace spider diagram is like that of N-MORB, so we consider that the metabasite was formed under the setting of mid-ocean ridge or adult back-arc basin, and it is the fragment of Paleo-Tethys ophiolite.N-MORB-type metabasites are discovered in the Guoganjianian area, central Qiangtang, Tibet, which are mainly metagabbro with cumulate structure and metabasalt. The rocks are distributed nearly from west to east unconformably underlying the Wanghuling Group of upper Triassic. On the basis of geo- chemical analysis, we find that the content of SiO2 is 43.03%―53.42%, and TiO2 1%―2.67%, Al2O3 16.75%―21.52%, CaO 7.03%―11.13%, K2O 0.05%―0.38%; the REE pattern is slight depletion or flat, and the trace spider diagram is like that of N-MORB, so we consider that the metabasite was formed under the setting of mid-ocean ridge or adult back-arc basin, and it is the fragment of Paleo-Tethys ophiolite.

关 键 词：Qiangtang  metabasite  Paleo-Tethys  OPHIOLITE 

分 类 号：P588.1[天文地球—岩石学]