湖北巴东栖霞组缺氧沉积环境的地球化学特征

Geochemistry of the dysaerobic sedimentary environments of the Qixia Formation in Badong,Hubei

关键词:  栖霞组  缺氧沉积  地球化学

Key words:  Qixia Formation  anoxic sediments  geochemistry

摘要:

地层的岩石地球化学特征是判断其形成环境氧化还原条件的重要手段之一。对湖北巴东水布垭剖面栖霞组中层纹状灰岩和含泥质灰岩的地球化学分析,结合鄂湘桂地区栖霞期区域沉积古地理背景及栖霞组沉积学、古生态学特征,表明该区栖霞组沉积于一贫氧的沉积背景。同时该研究表明大部分适用于判别泥质岩古氧相的痕量元素和稀土元素地球化学比值,如U/Th、Ni/Co、V/(V+Ni)和Ce/La也可适用于该组以钙质沉积为主的沉积物。但部分指示,如V/Cr在碳酸盐岩中的应用值得今后研究注意。

Abstract:

The geochemistry of sediments and/or rocks in the oxygen-deficient environments is commonly an important indicator for the interpretation of palaeoredox conditions. The analyses of twelve moderately laminated limestone and argillaceous limestone samples col-lected from the Lower Permian Qixia Formation of the Shuibuya section in Badong,Hubei, integrated with their sedimentary and palaeoecological characteristics,have confirmed that the carbonate successions in the study area were accumulated in a dysaerobic environment. In addition,it is suggested that most geochemical indices for the interpretation of palaeore-dox conditions inferred from ancient mudstones, for example, U/Th, Ni/Co, V/(V + Ni) and Ce/La except V/Cr,are also valid for the imterpretation of argillaceous limestones.