• 责任者：Zhang Cong (State Key Laboratory of Continental Tectonics and Dynamics ; Institute of Geology ; Chinese Academy of Geosciences ; Beijing 100037 ; China) ; Tian Zuolin
• 刊名：Geological Bulletin of China
• 出版年：2013
• 卷期：32(12)
• 关键词：榴辉岩 ; eclogite ; 柴达木盆地 ; Qaidam Basin
• 页码：p.2044-2054
• 图表：5 illus., 1 plate, 3 tables, 35 refs.
• 分类号：0802
• issnNo：ISSN1671-2552
• isbnNo：CN11-4648/P

     Eclogite, as an important rock type in the subduction zone, contains abundant geodynamic information of the earth. Studying the petrology of the eclogite and its retrogress equivalent helps building the p-T paths of the subduction zone and understanding the changes of the mineral facies and compositions of the subducted rocks and further constraining the exhumation mechanism in the subduction zone. This paper mainly focuses on the petrological studies of the bimineralic and phengite-bearing eclogite in the Xitieshan terrane, North Qaidam UHP metamorphic belt. We have calculated the p -T pseudosection of the eclgites under NC （K） FMASH system. It shows that the peak stage of the Bi-Ec preserved p-T conditions of 745-790℃, 〉2.8-3.0GPa （M1 stage） and experienced isothermal decompression to amphibole-eclogite facies p-T conditions （670-770℃, 1.6-2.2GPa,M2 stage）, which shows similar p-T path with the Phn-Ec. The Bi-Ec in the Xitieshan terrane has N-MORB geochemical characteristics, whereas the PhnEc shows E-MORB or OIB characters. It demonstrates that the protoliths of the Bim-Ec and Phn-Ec are different. Considering the p-T path and geochemical characters of the eclogite, it infers that the difference of the mineral assemblage between Bi-Ec and PhnEc are caused by the multiple origins of the eclogite protolith but not retrogression in the Xitieshan terrane.