Origin of the Lower Cretaceous lacustrine dolostones in Baiyinchagan Sag of Erlian Basin，Inner Mongolia
Guo Qiang1, Zhong Dakang1, Zhang Fangdong2, Liu Xingang2, Fan Lingxiao2, Li Junjun1
1 College of Geosciences，China University of Petroleum(Beijing)，Beijing 102249 2 Research Institute of Exploration and Development，Zhongyuan Petroleum Exploration Bureau，Puyang 457001，Henan
Abstract：In the Early Cretaceous，there was a set of lacustrine dolostones in the Baiyinchagan Sag with the strong rift extension and high geothermal anomaly.The dolostones were rich in special minerals including ankerite，natrolite，clay sized feldspar (albite,potash feldspar) etc.，and were only developed in semi-deep-deep lacustrine facies.The dolostone is controlled by NE-trending synsedimentary faults and distributed mainly in downthrown side of fault zone in northern steep slope zone and southern ramp zone adjacent to the central part in this sag.The lacustrine dolostone is mainly composed of ankerite and paragenetic minerals(natrolite，feldspar，barite，sjogrenite，etc.). Its texture can be divided into three types: micrite，microcrystalline and fine-medium grained porphyritic texture（multivariate mineral assemblage).The dolostone also has obvious rock fabric characteristics of hydrothermal sedimentation，including lamellar structure，hydrothermal clastic texture，starrily structure，contemporaneous plastic deformation and net vein structure.Based on the above preliminary analyses, we think that the formation of the lacustrine dolostone is the sedimentation with deep hydrothermal fluids participation，namely hydrothermal sedimentary dolostone.
Guo Qiang,Zhong Dakang,Zhang Fangdong et al. Origin of the Lower Cretaceous lacustrine dolostones in Baiyinchagan Sag of Erlian Basin，Inner Mongolia[J]. JOPC, 2012, 14(1): 59-68.
