青藏高原中生界白云岩特征研究及成因分析

通过对青藏高原羌塘盆地和措勤盆地的白云岩进行野外观察与描述,提出了研究区白云岩的纵、横向分布规律,总结了白云岩的岩石学特征。运用系统的室内分析、化验方法,应用结构标志、阴级发光标志、氧同位素标志有效地进行了白云岩成因判定。认为研究区的白云岩非原生成因,而均属于交代或白云化成因。根据白云岩中所含白云石的晶体大小、形态及内部结构划分了白云化阶段:准同生阶段、成岩阶段和后生阶段,并总结了各阶段白云岩的特征,认为成岩阶段形成的白云岩是油气最有利的储集层。通过选取典型剖面,归纳出研究区白云岩的两种成因模式:毛细管浓缩作用模式和混合水作用模式。

Character Study and Analysis of Dolomite of Mesozoic in Qingzang Plateau

After dolomites of Qiangtang Basin and Cuoqin Basin in Qingzang Plateau are observed and described in the field, vertical and horizontal distribution rules of dolomite in the study area are reduced. Applying structure index, cathode shining index and oxygen isotope index, genesis of dolomite are effectively judged by use of systematically indoor analysis and laboratory test method. Then it is concluded that dolomites of the study area are all produced by metasomatism or dolomitation, not originally. According to size and shape of crystals and inner structure of dolomites, dolomiting phase are divided into three phases: quasi-contemporaneous phase, diagenesis and catagenesis. Features of each phase are introduced . It is found that dolomites formed in diagenesis can be a good reservoir rock.Through selecting typical sections, two kinds of genetic models of dolomite in the study area are put forward, i.e. capillary concentration model and mixed water model.