用碳氧同位素对沱沱河盆地古近纪及新近纪早期气候变化的研究

Study of the climate change in the Tuotuo River basin by carbon and oxygen isotopes

鉴于目前对位于青藏高原上的沱沱河盆地研究不多,作者试用碳氧同位素比值的方法研究该地区新生代的始新世到中中新世这一时段内的气候环境变化情况。经过数据计算、图解和分析表明,沱沱河盆地从始新世到中中新世的气候环境变化可划分为两个阶段,即始新世—渐新世的炎热干燥气候期和中中新世的温暖湿润气候期。此研究结果将为进一步研究该地区的古环境变化提供依据。

The Tuotuo River basin lies in the Qinghai-Tibet Plateau. In fact, the Tuotuo River basin has been researched little, so the authors try to study its climate change from Eocene to Miocene by carbon and oxygen isotopes. The strata of the Tuotuo River basin can be divided into 3 parts, that is, Tuotuo River group, Yaxieuo group and Wudaoliang group. The geological age of the Tuotuo River group is the Paleoeene epoch-Eocene epoch. It is a set of coarse elastic rocks. The geological age of the Yaxicuo group is the Eocene epoch-Oligoeene epoch. It is a set of middle-fine elastic rocks. The geological age of the Wudaoliang group is the Miocene epoch. It is a set of carbonate rocks. The authors have got carbon and oxygen isotopes from the Yaxicuo group and Wudaoliang group. But they have not got carbon and oxygen isotopes from the Toutou River group. By carbon and oxygen isotopes analysis they conclude finally that the climate environment changes of the Tuotuo River from Eocene to Miocene ought to be divided into two phases. One phase is the hot and dry climate from Eocene to Oligocene, and the other phase is the warm and wet climate from Oligoeene to Miocene. Besides, they conclude that the climate from Paleoeene to Oligocene is a kind climate of hot and wet by sediment analysis and sporopollen analysis. This researched result will provide a scientific basis for further researching the ancient environment of this area.