扬子板块西南部古元古代岩浆及变质事件——兼论扬子板块对Nuna超大陆事件的响应  

Paleoproterozoic magmatic and metamorphic events in southwestern Yangtze Block: The position and evolution of the Yangtze Block within the Nuna supercontinent

作　　者：张恒[1] 高林志[1] 张传恒[2] 丁孝忠[1] 李廷栋[1] 宋彪[1] 刘昊岗 龚成强 张继彪 ZHANG Heng;GAO Linzhi;ZHANG Chuanheng;DING Xiaozhong;LI Tingdong;SONG Biao;LIU Haogang;GONG Chengqiang;ZHANG Jibiao(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质大学(北京),北京100083

出　　处：《地质通报》2019年第11期1777-1789,共13页Geological Bulletin of China

基　　金：中国地质调查局项目《全国地质构造区划与区域地质调查综合集成》（编号：DD20160345）和《中国及邻区海陆大地构造研究和相关图件编制》（编号：DD20160343）

摘　　要：寻找扬子板块西南地区古老结晶基底一直是众多地质学者追寻的目标,其涉及扬子板块在Nuna超大陆重建中的位置和演化过程,也是前寒武纪研究的重要课题。继在扬子板块西南部中国云南石屏撮科村首次报道2.35Ga花岗片麻岩结晶基底后,又在撮科村-高家坡一带3个花岗岩样品中分别获得了2347.3±4.9Ma、2324.3±8.6Ma和2329.4±5.9Ma的SHRIMP锆石U-Pb年龄,进一步确认扬子板块西南部中国境内存在2.32~2.35Ga的岩浆事件,其应为Nuna超大陆汇聚期Arrowsmith造山事件在扬子板块的响应。另在1件糜棱岩化花岗闪长岩样品中获得了1909.8±5.7Ma和1843.1±7.6Ma两组年龄,在扬子板块西南部中国境内首次发现1.90Ga和1.84Ga的构造或变质事件。结合前人研究成果,确定扬子板块西南部存在2.91~2.84Ga,2.36~2.32Ga,2.28~2.19Ga的岩浆事件,以及1.97~1.95Ga,1.90Ga,1.84~1.83Ga的变质事件,为确定扬子板块在Nuna超大陆重建中的位置提供了更多证据。The search for crystalline basement outcrops in the southwestern portion of the Yangtze Block has been the study object of many geologists, and the position and the evolution of the Yangtze Block within the Precambrian supercontinent of Nuna have also been an important research subject. In this study, SHRIMP zircon U-Pb dating was conducted for three granite samples underlying the Kunyang Group and, as a result, the weighted mean207 Pb/206 Pb ages of 2347.3±4.9 Ma, 2324.3±8.6 Ma, and 2329.4±5.9 Ma were obtained respectively. These data further confirm that there were 2.32~2.35 Ga magmatic events in the southwest Yangtze plate,which were the response of the Yangtze Block to the Arrowsmith orogenic event with the assembly of the Nuna supercontinent.Especially a sample yielded weighted mean207 Pb/206 Pb ages of 1909.8±5.7 Ma and 1843.1±7.6 Ma, which indicate for the first time the existence of two periods of metamorphism respectively at 1.90 Ga and 1.84 Ga in the southwestern portion of the Yangtze Block.Along with previous researches, the authors have reached the conclusion that there were 2.91~2.84 Ga, 2.36~2.32 Ga and 2.28~2.19 Ga magmatic events and 1.97~1.95 Ga, 1.90 Ga and 1.84~1.83 Ga metamorphic events in the southwest Yangtze Block. These data provide important evidence for ascertaining the position and the evolution of the Yangtze Block within the supercontinent of Nuna.

关 键 词：扬子板块 Nuna超大陆 滇中地区 结晶基底 

分 类 号：P534.3[天文地球—古生物学与地层学] P588.11[天文地球—地质学]