Confirmation of pelitic granulite in the Altai orogen and its geological significance  

作　　者：WANG Wei WEI ChunJing WANG Tao LOU YuXing CHU Hang 

机构地区：[1]MOE Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China [2]School of Geosciences, University of Sydney, Sydney 2006, AustraLia [3]Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China

出　　处：《Chinese Science Bulletin》2009年第14期2543-2548,共6页

基　　金：Supported by the National Natural Science Foundation of China (Grant No. 40525006);Ministry of Education of China (Grant No. 20060001062);China Survey of Geology

摘　　要：The existence of pelitic granulite in the Altai orogen was confirmed for the first time by detailed petrographic research and P-T pseudosection modeling. The pelitic granulite has the assemblage of garnet + cordierite + K-feldspar + biotite + sillimanite + plagioclase + quartz with some samples containing the paragenesis of cordierite + spinel. Peak conditions of the pelitic granulite determined from the P-T pseudosection involved P = 0.5―0.6 GPa, T = 780―800℃, belonging to medium-to low-pressure type. SHRIMP U-Pb dating of zircon presented a metamorphic age of 292.8 ± 2.3 Ma. The discovery of pelitic granulite reflects an extensional environment with high heat flow in the southern margin of the Altai orogen during the Early Permian, which provides an important petrological constraint on the evolution of the Altai orogen.The existence of pelitic granulite in the Altai orogen was confirmed for the first time by detailed petrographic research and P-Tpseudosection modeling. The pelitic granulite has the assemblage of garnet ＋ cordierite ＋ K-feldspar ＋ biotite ＋ sillimanite ＋ plagioclase ＋ quartz with some samples containing the paragenesis of cordierite ＋ spinel. Peak conditions of the pelitic granuUte determined from the P-T pseudosection involved P = 0.5-0.6 GPa, T= 780-800℃ belonging to medium- to low-pressure type. SHRIMP U-Pb dating of zircon presented a metamorphic age of 292.8 ± 2.3 Ma. The discovery of pelitic granulite reflects an extensional environment with high heat flow in the southern margin of the Altai orogen during the Early Permian, which provides an important petrological constraint on the evolution of the Altai orogen.

关 键 词：阿尔泰造山带 麻粒岩 泥质 地质意义 SHRIMP 锆石年龄 早二叠世 堇青石 

分 类 号：P542.2[天文地球—构造地质学] P588.346[天文地球—地质学]