西藏吉隆盆地沃马剖面元素地球化学特征及环境指示意义

Geochemical Characteristics of the Oma Section in the Tibetan Gyirong Basin and Its Implications on Environment Change

通过对西藏吉隆盆地沃马剖面上变价元素Fe、Mn的赋存形态分析,根据变价元素不同赋存形态含量与古气候的关系,探讨青藏高原隆升过程中的环境变迁历程.应用元素地球化学原理,参考常规常量元素指标和测年资料,确定了该剖面10.0～1.7Ma来地球化学元素的分布规律.研究结果表明:该剖面地层沉积时的地球化学环境历经强还原状态到弱氧化状态再到还原状态的变化过程,其对应古气候呈现由干冷转向暖湿再到干冷的变化.

Based on the study of the combining forms of the valence-variable elements such as Fe and Mn at the Oma section in the Gyirong basin, Tibet, and on the relation of the contents of the various forms of the valence-variable elements with climate conditions, the environmental change during the rising of the Qinghai-Tibet plateau is discussed. The distribution rules of the geochemical elements during 10. 0-1.7 Ma of the Oma section were ascertained with element geochemistry principles applied and dating data as well as indexes of the conventional and major elements analyzed. The results show that in the sedimentary period of the profile, while the geochemical environment changed from strong reduction state through weak oxidation state to reduction state, the paleoclimate varied from dry-cold through warm wet to dry-cold accordingly.