| In this paper,according to the current research of the western region Ordos Majiagou Formation carbonate rocks,four division of sedimentary microfacies and sedimentary facies distribution and other aspects and problems,writer constructs the carbonate geology,stratigraphy and sedimentology theory,uses the methods of field and indoor,the combination of macro and micro,description, outcrops and cores observation of the conventional micro fine thin section observation and identification based on analysis of data,combines with the carbon and oxygen isotope,studies the stratigraphic framework,sedimentary facies,sedimentary facies marks,vertical combination sequence,plane distribution.Based on the regional geological background, geological tectonic history, the characteristics of lithology paleontology, log curves is analyzed.lt is concluded that in horizontally, the middle of the research region layer is thick and the sides of the research region layer is thin,from the south to north the layer becomes thick gradually. In the flat, regarding the QiTanl E19YuTanl as the boundary, the thickness of the layer in the west can be found apparently law, from the east to west, the thinkness of the layer becomes thick., the higher roots of the layer thickness in the east of Masi section is the Dingbian region, and it becomes thin to the neighboring regions gradually.Summarizing the sedimentary features of Majiagou Formation in the study area, it will be divided into carbonate platform facies and carbonate gentle slope of two kinds of sedimentary facies, and can be further divided into6subfacies and some microfacies. In horizontally, from the west to east the carbonate gentle slope composed by the deep sea basin the deep slope and the gentle slope transits to the carbonate platform facies composed by the shoal and shoal platform-flat. With the further expansion of transgression process, seawater intrusion direction with early invasion of the same direction, the restricted platform inside the cloud Ping area has the trend of significantly reduced, sediment types in a grey dolomite and mud containing local cloud of mud limestone. It is mainly open platform deposition, sediment types in dark gray thick bedded and massive micritic limestone, grain limestone and fine crystal powder dolomite. The study area four section plane sedimentary facies variation regularity is obvious, from west to East, are developed in deep sea basin slope, deep slope, gentle slope and shoal tidal-flat platform sedimentary facies, this view has an important guiding significance for the exploration and development of oil and gas. |
