湖南桃源郝坪奥陶系五峰组顶部斑脱岩LA-ICP-MS锆石U-Pb年龄  

LA-ICP-MS zircon U-Pb dating of the bentonites from the uppermost part of the Ordovician Wufeng Formation in the Haoping section,Taoyuan,Hunan

作　　者：谢尚克[1] 汪正江[1] 王剑[1] 卓皆文[1] 

机构地区：[1]成都地质矿产研究所,四川成都610081

出　　处：《沉积与特提斯地质》2012年第4期65-69,共5页Sedimentary Geology and Tethyan Geology

基　　金：青藏高原非常规油气调查(编号:1212011221106);国家自然科学基金项目(编号:40972087;41072088)

摘　　要：为了认识奥陶纪-志留纪之交的火山活动及事件年龄,对湖南桃源郝坪剖面的斑脱岩进行了LA-ICP-MS锆石U-Pb定年。结果表明,五峰组顶部斑脱岩LA-ICP-MS锆石U-Pb年龄为442.2±8.1 Ma,该年龄反映了扬子地区奥陶纪-志留纪之交火山活动的时代,与国际地层委员会公布的奥陶系-志留系界线年龄(443.7±1.5Ma)相一致,同属晚奥陶世。奥陶纪-志留纪之交的火山活动对于探讨晚奥陶世生物绝灭、沉积环境变化与年代地层对比具有重要的意义。The LA-ICP-MS zircon U-Pb age of 442.2± 8.1 Ma is obtained for the bentonite from the uppermost part of the Ordovician Wufeng Formation in the Haoping section, Taoyuan, Hunan. This age represents that of the volcanic activities in the Yangtze area during the Ordovician - Silurian boundary, and coincides with the age of 443.7 ±1.5 Ma for the Ordovician - Silurian boundary published by the International Commission on Stratigraphy. The Ordovician - Silurian volcanic activities may have important implications for the insights into the Late Ordovician biotic extinction, sedimentary environmental changes and chronostratigraphic correlation in the study area.

关 键 词：郝坪 LA—ICP—MS锆石U—Pb年龄 晚奥陶世 火山活动 生物灭绝 

分 类 号：P588.211[天文地球—岩石学]