Polymetamorphism of the ultrahigh-temperature granulites in the Rauer Group,East Antarctica:new evidence from zircon SHRIMP U-Pb ages  

作　　者：TONG Laixi LIU Zhao LI Chao LU Junsheng YANG Wenqiang WANG Yanbin 

机构地区：[1]State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an 710069,China [2]Institute of Geology,Chinese Academy of Geological Sciences,Bejing 100037,China

出　　处：《Advances in Polar Science》2024年第2期192-205,共14页极地科学进展（英文版）

基　　金：supported by the National Nature Science Foundation of China(Grant no.41972050).

摘　　要：The Rauer Group is located on the eastern margin of the early Paleozoic Prydz Belt in East Antarctica,and the typical ultrahigh-temperature(UHT,>900℃)granulites outcrop on Mather Peninsula.However,the timing of UHT metamorphism and P–T path of the UHT granulites have long been debated,which is critical to understanding the tectonic nature and evolution history of the Prydz Belt.Thus,both a sapphirine-bearing UHT metapelitic granulite and a garnet-bearing UHT mafic granulite are selected for zircon SHRIMP U-Pb age dating.The results show that metamorphic zircon mantles yield weighted mean^(206)Pb/^(238)U ages of 918±29 Ma and 901±29 Ma for the metapelitic and mafic granulites,respectively,while zircon rims and newly grown zircons yield weighted mean^(206)Pb/^(238)U ages of 523±9 Ma and 532±11 Ma,respectively.These new zircon age data suggest that the UHT granulites may have experienced polymetamorphism,in which pre-peak prograde stage occurred in the early Neoproterozoic Grenvillian orogenesis(1000–900 Ma),whereas the UHT metamorphism occurred in the late Neoproterozoic to early Paleozoic Pan-African orogenesis(580–460 Ma).This implies that P–T path of the UHT granulites should consist of two separate high-grade metamorphic events including the Grenvillian and Pan-African events,which are supposed to be related to assembly of Rodinia and Gondwana supercontinents respectively,and hence the overprinting UHT metamorphic event may actually reflect an important intracontinental reworking.

关 键 词：ultrahigh-temperature granulites zircon SHRIMP U-Pb ages POLYMETAMORPHISM Rauer Group East Antarctica 

分 类 号：P588.3[天文地球—岩石学]