中文摘要：

在岩石学分析基础上，结合碳氧同位素分析方法对柴达木盆地大红沟和鄂博梁剖面上、下干柴沟组湖相碳酸盐岩样品进行系统研究，试图阐述不同类型湖相碳酸盐岩的古气候特征，研究该时期柴达木盆地古气候演化历史。结果显示：该地区湖相碳酸盐岩可以分为生屑灰岩、砂屑灰岩、藻灰岩、鲕粒灰岩、泥晶灰岩5大类。不同类型的碳酸盐岩样品的碳、氧同位素组成特征存在明显区别，且都为正值，形成于炎热干燥的古气候和咸水沉积环境中；藻灰岩类明显富集13C的特。点与藻类等水生生物活动密切相关，反映沉积于温暖干燥气候背景下的一个水体盐度偏高的稳定水体之中；生屑灰岩和砂屑灰岩类都比较集中，且表现出明显的低值，反映形成于温暖湿润气候条件下且具淡水补给的开放性湖泊环境；泥晶灰岩类样品的伊。之间具有一定的正相关性，反映发育在水体停滞、蒸发作用明显的咸水型湖泊体系。

英文摘要：

Systematic petrology and carbon-oxygen isotope analysis has been made on the lacustrine carbon ate rocks in the upper Ganchaigou Formation and lower Ganchaigou Formation from Dahonggou and Ebo liang strata section in the Qaidam Basin. This study attempts to elaborate the paleoclimatie characteristics and environmental evolution of the Cenozoic in this basin represented by different types of the lacustrine carbonate rocks. Five types of lacustrine carbonate rocks in the study area are identified and classified as bioclast limestone, calcarenite, algal limestone, oolitic limestone and micrite limestone. Each type of carbonate rocks have obvious different characteristics of carbon-oxygen isotopes. and in the bioclas-tic limestone and calcarenite samples have the lowest values in all the samples in this area, reflecting an open freshwater lacustrine environment deposition with cold climate condition. Obvious enriching of in algal limestone maybe related to low-grade hydrophyte and phytoplankton activities, reflecting a high salinity steady water lacustrine deposition environment with the warm and dry climate condition. The and in the oolitic limestone samples have the highest and positive values, reflecting a saline water 1a custrine deposition environment with hot and dry circumstances. There is a positive relation between the and in the micritic limestone samples, indicating an obvious closed saline water lacustrine deposi- tion environment.