青藏高原沱沱河盆地中新统五道梁组沉积特征及古环境分析

通过对青藏高原沱沱河盆地五道梁组湖相沉积环境的分析，尝试通过湖相沉积地层记录提取气候变化信息，探索高原腹地中新世古环境变化特点。通过对五道梁组岩石类型及沉积特征研究，识别出了洪积平原、浅湖、滨湖、深湖及盐湖5个沉积相类型。参考现代湖泊特征与古代研究实例，探讨了研究区湖相碳酸盐岩的沉积机制。根据剖面岩相标志及地层叠置样式，证实五道梁组沉积期古湖泊经历了3次由低水位变为高水位的旋回性变化，湖泊最低水位期以石膏层的出现为标志，高水位期发育洪泛泥岩沉积；初步认为五道梁组沉积发育在一个干湿交替的气候期，湖水位变化和湖平面升降主要受气候控制，而构造沉降和湖缘断块隆升是次要控制因素。

Sedimentary characteristics of the Miocene Wudaoliang Formation in Tuotuohe Basin of Qinghai-Tibet Plateau and palaeoenvironment analysis

Analyses have been carried out on the lacustrine setting of the Wudaoliang Formation in the Tuotuohe Basin of Qinghai Tibet Plateau. The study focuses on information of  climate changes reflected by the sedimentary stratigraphic records and investigates the palaeoenvironmemt changes in the plateau in the Miocene. Rock types and sedimentary characteristics of the Wudaoliang Formation were analyzed and flood plain， shallow lacustrine， shore lacustrine and salt lake sedimentary facies were recognized. With reference to the present lacustrine features and the study examples of ancient lakes， the sedimentary origins of the lacustrine carbonates in the study area were discussed. The facies markers in the section and the stratigraphic stacking patterns indicate that the palaeolake experienced three cycles of low lake level to high lake level changes during the deposition of the Wudaoliang Formation. The minimum lake level is marked by the occurrence of the gypsum interval， while the high lake level period is characterized by the deposition of flooding mudstones. The results indicate that the depositional setting of the Wudaoliang Formation was dominated by a dry wet climate alternation， lake level change and the fluctuation is mainly influenced by climate with structural subsidence and fault block uplifting as the secondary controlling factors.
 Qinghai Tibet Plateau， Wudaoliang Formation， sedimentary facies， palaeoevironment