Determination of the early Paleozoic accretionary complex in Southwestern Yunnan, China: Implications for the tectonic evolution of the Proto-Tethys Ocean  

作　　者：Guo-chuan Yan Bao-di Wang Han Liu Juan He Zhi-min Peng 

机构地区：[1]Graduate School of Chinese Academy of Geological Sciences,China Geological Survey,Ministry of Natural Resources,Beijing 100037,China [2]Chinese Academy of Geological Sciences,China University of Geosciences,Beijing 100083,China [3]China Aero Geophysical Survey and Remote Sensing Center for Natural Resources,China Geological Survey,Ministry of Natural Resources,Beijing 100083,China [4]Chengdu Center of Geological Survey,China Geological Survey,Ministry of Natural Resources,Chengdu 610081,China [5]West Yunnan University of Applied Sciences,Dali 671006,Yunnan China

出　　处：《China Geology》2023年第2期322-337,I0016-I0041,共42页中国地质（英文）

基　　金：supported by the Second Comprehensive Scientific Investigation and Research Program on the Qinghai-Tibet Plateau(2019QZKK0702);the China Geological Survey Program(DD20221715,DD20190053).

摘　　要：Accretionary complex study provides important knowledge on the subduction and the geodynamic processes of the oceanic plate,which represents the ancient ocean basin extinction location.Nevertheless,there exist many disputes on the age,material source,and tectonic attribute of the Lancang Group,located in Southwest Yunnan,China.In this paper,the LA-ICP-MS detrital zircon U‒Pb chronology of nine metamorphic rocks in the Lancang Group was carried out.The U‒Pb ages of the three detrital zircons mainly range from 590-550 Ma,980-910 Ma,and 1150-1490 Ma,with the youngest detrital zircons having a peak age of about 560 Ma.The U‒Pb ages of the six detrital zircons mainly range from 440-460 Ma and 980-910 Ma,and the youngest detrital zircon has a peak age of about 445 Ma.In the Lancang Group,metamorphic acidic volcanic rocks,basic volcanic rocks,intermediate-acid intrusive rocks,and high-pressure metamorphic rocks are exposed in the form of tectonic lens in schist,rendering typical melange structural characteristics of“block+matrix”.Considering regional deformation and chronology,material composition characteristics,and the previous data,this study thinks the Lancang Group may be an early Paleozoic tectonic accretionary complex formed by the eastward subduction of the Changning-Menglian Proto-Tethys Ocean,which provides an important constraint for the Tethys evolution.

关 键 词：Early Paleozoic Accretionary complex Langcang Group Block+matrix Proto-Tethys Ocean Geological survey engineering Eastern margin of Qinghai-Tibet Plateau 

分 类 号：P542[天文地球—构造地质学] P534.4[天文地球—地质学]