Detrital Zircon U-Pb Geochronology and Lu-Hf Isotopic Compositions of the Wuliangshan Metasediment Rocks in SW Yunnan(China)and Its Provenance Implications  

作　　者：Xiaowan Xing Yuejun Wang Yuzhi Zhang 

机构地区：[1]State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China [2]School of Earth Science and Geological Engineering,Sun Yat-sen University,Guangzhou 510275,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]CAS Center for Excellence in Tibetan Plateau Earth Sciences,Beijing 100101,China

出　　处：《Journal of Earth Science》2016年第3期412-424,共13页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundationof China(No.41190073);the National Basic Research Program of China(No.2014CB440901);the Fundamental Research Funds for the Central Universities to SYSU

摘　　要：The Wuliangshan Group occurs to the east of the Lancang giant igneous zone in SW Yunnan, and is mainly composed of low-grade metamorphosed sedimentary rocks. The group has been considered as the syn-orogenic product of the Baoshan with Simao-Indochina blocks. However, its depositional time and provenance remain to be poorly constrained. This paper presents zircon U-Pb dating and Lu-Hf-isotopic data for five representative sandstone samples from the Wuliangshan Group. The detrital grains yield a major age-peak at ~259 Ma, and four subordinary age-peaks at ~1 859, ~941, ~788, and ~447 Ma, respectively. Our results suggest that the Wuliangshan metasedimentary sequence was deposited after Middle Triassic rather than previously-thought Cambrian. The detrital zircon age spectrum, along with in-situ Lu-Hf isotopic data suggest that the Wuliangshan Group might be a syncollisional sedimentary product related to the collision of Baoshan with Simao-Indochina blocks. It is inferred that the provenance of the Wuliangshan Group is mainly from the Simao/Yangtze blocks to the east rather than the Baoshan Block or Lancang igneous zone to the west.The Wuliangshan Group occurs to the east of the Lancang giant igneous zone in SW Yunnan, and is mainly composed of low-grade metamorphosed sedimentary rocks. The group has been considered as the syn-orogenic product of the Baoshan with Simao-Indochina blocks. However, its depositional time and provenance remain to be poorly constrained. This paper presents zircon U-Pb dating and Lu-Hf-isotopic data for five representative sandstone samples from the Wuliangshan Group. The detrital grains yield a major age-peak at ~259 Ma, and four subordinary age-peaks at ~1 859, ~941, ~788, and ~447 Ma, respectively. Our results suggest that the Wuliangshan metasedimentary sequence was deposited after Middle Triassic rather than previously-thought Cambrian. The detrital zircon age spectrum, along with in-situ Lu-Hf isotopic data suggest that the Wuliangshan Group might be a syncollisional sedimentary product related to the collision of Baoshan with Simao-Indochina blocks. It is inferred that the provenance of the Wuliangshan Group is mainly from the Simao/Yangtze blocks to the east rather than the Baoshan Block or Lancang igneous zone to the west.

关 键 词：detrital zircon U-Pb dating Lu-Hf isotopic composition Wuliangshan sandstone sequence Middle Triassic Simao-Indochina 

分 类 号：P588.3[天文地球—岩石学] P588.21[天文地球—地质学]