【摘要】 研究了广西来宾铁桥剖面栖霞组的黏土矿物组合和地球化学特征的纵向变化特征。黏土矿物分析结果表明,栖霞组上部和下部地层中,黏土矿物含量较高,以伊利石、绿泥石为主,含少量的高岭石和蒙脱石;中部地层中黏土矿物含量较少。在电子显微镜下,有些黏土矿物,如伊利石,发育在草莓状黄铁矿晶体之间,形成于早期成岩作用阶段。整体上黏土矿物成因与陆源碎屑物质输入有关。配套的地球化学分析表明,Al、Fe和Ti质量分数等反映陆源物质的指标,在栖霞组下部和上部质量分数较高,中部明显较低。上述黏土矿物分析和地球化学测试结果意味着该地区二叠纪栖霞期呈现一个明显的陆源碎屑物质输入旋回变化,早期和晚期陆源物质供应较明显,而中期较贫乏,可为该区进一步古地理研究提供重要参考。更多还原

【Abstract】 It is still unsolved whether there were paleolands during the biggest middle Permian transgression in the South China region in the past two decades. It is even hard to know if those paleolands sheded terrigenous materials into th eir surrounding marine environments.In order to evaluate the variation of the t errigenous input during the Chihsian time,this research analyses the clay miner als and geochemistry of the Chihsia Formation of Tieqiao section in Guangxi.Min eralogical results indicate that illite,chlorite and a minor content of kaolini te and montmorillonite(without excluding the sepiolite),are the clay minerals recorded in the Chihsia Formation.The distribution of the phyllosilicate shows the high content of illite and chlorite in the lower and the upper parts of the formation,which decreases in the middle one.The clay minerals are considered t o be mainly detrital in origin and also authigenic where pyrite has grown on the illite.Geochemical analysis demonstrates that the contents of element Al,Fe, and Ti,common index of terrigenous input,are higher in the lower and the upper parts than those in the middle part of the succession.Both the mineralogical a nd geochemical results imply an evident cyclic variation of terrigenous input,f rom decrease to increase,during the Chihsian time,and should be of significanc e for further paleogeographic reconstruction.更多还原