SHRIMP zircon U-Pb geochronology of Indosinian granites in Hunan Province and its petrogenetic implications  

作　　者：WANGYuejun FANWeiming LIANGXinquan PENGTouping SHIYuruo 

机构地区：[1]KeyLaboratoryofIsotopeGeochronologyandGeochemistry,GuangzhouInstituteofGeochemistry,ChineseAcademyofSciences,Guangzhou510640,China [2]SHRIMPIsotopeLaboratory,ChineseAcademyofGeologicalSciences.Beijing100037,China

出　　处：《Chinese Science Bulletin》2005年第13期1395-1403,共9页

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.40334039,40421303 and 40473019);the Chinese Academy of Sciences(Grant No.KZCX2-102)

摘　　要：The SHRIMP zircon U-Pb geochronology ofthree typically Indosinian granitic plutons with peralumi-nous and potassium-rich affinities (Tangshi ultraunit forWeishan and Baimashan, and Longtan ultraunit forGuandimiao) is presented in Hunan Province, South China.The analyses of zircons from biotite monozonite granites forWeishan, Baimashan and Guandimiao plutons show the sin-gle and tight clusters on the concordia, and yield theweighted mean 206Pb/238U ages of 244±4, 243±3 and 239±3Ma, respectively, representing the crystallized ages of theseIndosinian granites. These data suggest that the Indosiniangranitic plutons as previously thought formed at a narrowage span. In combination with other data, it is inferred thatthe Indosinian granites within the South China Block proba-bly distributed in Hunan, Jiangxi, Guangxi and Guangdongprovinces as planar shape, and were the derivation of thecrustal materials in the intracontinental thickening setting.These precisely geochronological data provide importantconstraints for better understanding the spatiotemporal pat-tern of the Indosinian peraluminous granites and earlyMesozoic tectonic evolution of the South China Block.The SHRIMP zircon U-Pb geochronology of three typically Indosinian graniticpinions with peraluminous and potassium-rich affinities (Tangshi ultraunit for Weishan andBaimashan, and Longtan ultraunit for Guandimlao) is presented in Hunan Province, South China. Theanalyses of zircons from biotite monozonite granites for Weishan, Baimashan and Guandimlao platensshow the single and tight clusters on the concordia, and yield the t weighted mean Pb/23SU ages of244 + - 4, 243+ - 3 and 239+3 Ma, respectively, representing the crystallized ages of theseIndosinian granites. These data suggest that the ladosiniaa granitic plntons as previously thoughtformed at a narrow age span. In combination with other data, it is inferred that the Indosiniangranites within the South China Block probably distributed in Hunan, Jiangxi, Guangxi and Guangdongprovinces as planar shape, and were the derivation of the crustal materials in the intracontinentalthickening setting. These precisely geochronological data provide important constraints for betterunderstanding the spatiotemporal pattern of the Indosinian peralaminous granites and early Mesozoictectonic evolution of the South China Block.

关 键 词：锆石 地球年代学 花岗岩 岩石学 

分 类 号：P58[天文地球—岩石学]