渝东南下寒武统黑色岩系稀土元素地球化学特征与沉积环境

REE geochemical signatures and sedimentary environments of the Lower Cambrian black rock series in southeastern Chongqing and its adjacent areas

渝东南及周边地区下寒武统黑色岩系稀土总量略低于北美页岩,∑LREE/∑HREE值为1.99～9.01,平均6.86,轻稀土相对富集;δEu值为0.69～7.33,平均2.79;δCe值为0.70～1.01,平均0.85。区内下寒武统黑色岩系为正常海水与热水沉积作用的混合产物,形成于缺氧还原环境逐渐向弱氧化环境过渡的外陆架。

The Lower Cambrian black rock series in southeastern Chongqing and its adjacent areas are characterized by less-enriched ΣREE,ΣLREE/ΣHREE ratios ranging between 1.99 and 9.01 with an average of 6.86,relatively Enriched LREE,δEu values ranging between 0.69 and 7.33 with an average of 2.79,and δCe values ranging between 0.70 and 1.01 with an average of 0.85.The results of research in the present paper show that the Lower Cambrian black rock series in the study area resulted from the mixing of the normal seawater and hot seawater deposition in the transitional conditions from the anoxic reducing environments to the weakly oxidized environments on the outer continental shelves.