摘要
通过对恩施地区二叠系-三叠系界线附近含凝灰质黏土岩的野外地质学特征调查,采用锆石U-Pb同位素测试分析,取得其206Pb/238 U加权平均年龄为251.6±1.2Ma,该年龄值为二叠系-三叠系界线附近的火山喷发事件的年龄。结合碳和氧同位素分析,二叠系-三叠系界线附近黏土层之上碳同位素明显负偏,这与该时期生物绝灭事件关系密切。通过区域对比,发现该套黏土岩在区域上可进行连续追踪,不同地区界线附近岩石组合差异性明显,二叠系顶部自西向东总体表现为碳酸盐岩比例逐渐减少、碳硅质岩逐渐增加的特征。
We carried out a regional geological survey focusing on the tuffaceous claystone at the Permian Triassic boundary in the Enshi area of Hubei Province. Here we report a zircon U-Pb age of 251. 6 ± 1.2 Ma（weighted mean ^206Pb/^238U age） from this boundary clay layer. This represents the age of volcanic eruptions near the Permian-Triassic boundary. Carbonate carbon isotope data show a negative excursion just above the boundary clay layer. This excursion is closely related to the Permian-Triassic extinction e- vent. According to regional correlation, this claystone has a wide distribution in the studied region. How- ever, there are recognizable regional lithostratigraphic variations below the claystone, uppermost carbonate strata thin from west to east in the studied region, whereas carbonaceous siliceous roc Permian ks thicken.
作者
石先滨
邓杰
段先锋
罗红
翁茂芝
SHI Xian-bin DENG Jie DUAN Xian-feng LUO Hong WONG Mao-zhi(Hubei Geological Survey, Wuhan 43003)
出处
《地层学杂志》
CSCD
北大核心
2017年第3期327-334,共8页
Journal of Stratigraphy
基金
中国地质调查局大调查项目(No.12120113061800)
中国地质调查局扬子工程湘西-鄂西成矿带神农架-花垣地区地质矿产调查二级项目(No.DD20160029)
关键词
岩石地层
化学地层
二叠系-三叠系界线
U—Pb年龄
碳和氧同位素
恩施
湖北
lithostratigraphy, chemistratigraphy, Permian-Triassic boundary, U-Pb age, carbon and oxy-gen isotope, Enshi, Hubei Province
