【摘要】 青藏高原中部新生代湖泊发育普遍.对该时期形成的湖相白云岩特征的研究对于了解当时及此后青藏高原的环境演化进程具有重要意义.笔者主要利用XRD、SEM及薄片观察方法对沱沱河地区两个剖面的白云石特征进行了研究,分析了白云石有序度、晶形及白云石中碳酸钙摩尔浓度三者之间的关系,并根据白云石的矿物学和岩石学特征以及野外宏观岩层组合特征对白云岩的成因作出了判断,进而联系同一时期高原内部以及周边地区的构造运动导致的环境变化,对剖面所代表地区沉积时的环境变化作了解释.更多还原

【Abstract】 Lakes developed widely during Cenozoic era in central Tibetan Plateau. Researches on those lacustrine dolomite formed in that period is highly significaive to analyze the evolutionary process of Tibetan Plateau environment from then on. XRD, SEM and thin section analytical approaches were applied to analyze the relationship among Degree Order, crystal shape and the CaCO3 molal fraction of the dolomite samples took from Tuotuohe area. Based on the mineralogy and petrology features, investigation depends on the field work on the outcrops, and the origin mode of dolomite are diagnosed. Furthermore, the environmental changes recorded within the sedimentary sections are interpreted in connection with some tectonic movements which led environmental changes internal or external the Plateau.更多还原