The Sedimentary Features Of Zhuozishan Area In The West Margin Of Odros Basin And The Significance To Oil And Gas Accumulation

West margin of Ordos Basin in Zhuozi Mountain region, located in the tectonic massif of the east part and west part of China north south tectonic belt of the northern section of the important tectonic position, on the west side of North for Alashan block, Eastern Ordos massif, South Qinling Qilian orogenic belt, through the complex tectonic evolution.The study of lithofacies and paleo geography is the basis of oil and gas exploration. To the west margin of the Ordos Basin, Upper Ordovician as the object of study by analysis of measured and observed profile, the sedimentology theory as guidance combined with a variety of means analysis, in-depth analysis of the characteristics of rock type and causes, and analysis of sedimentary environment.There are two different types of sedimentary assemblages in the Ordovician of the western margin of the Ordos Basin. One kind of sedimentary facies is a set of carbonate rocks, and the other is not obvious,Zhuozi Mountain Region in the Austrian Ordovician kelimoli Fm from the bottom to the top can be divided into three sections, under section for shallow grey dark grey thin mud crystal-crystal powder limestone clip very dark gray thin bedded mudstone, limestone boundary roughness was nodular, beaded; the middle section is dark gray medium-thin limestone clip very dark gray thin bedded mudstone in combination with black mudstone interbed; upper black stripe shaped calcareous mudstone, top with dark gray massive calcirudite and Ulla Lectra Fm boundaries. The Fm located in carbonate rock platform to deep-water basin transition zone, especially in the thin layer of limestone kelimoli Fm is stage of the transformation of sedimentary environment. The sedimentary features of the black shale are mainly black shale, and the bottom is a layer of gravel. Composition of unequal thickness lashizhong consists of sandy, silty turbidite and shale interbedded.Table mountain region in the short end Cambrian sedimentary fractured in the early Ordovician-Austrian Ordovician early basically is a set of carbonate deposits. In the Austrian Ordovician to the middle and late Ordovician early, due to intense tectonic activity in the study area, because of tectonic movement and rapid depression depression, Ordos Basin on the western margin of the regions of the developing of the Helanshan crack subsidence basin on the eastern side of the slope, sediment were significantly different, phase transformation was accelerated. And the strengthening of the regional tectonic activities, for the deep water gravity flow formation provides the basic trigger mechanism and gradient conditions. Kelimoli Fm under thin micritic-powder limestone clip very dark gray thin bedded mudstone and deep flow transformation of the role of the formation of nodular limestone; on the eastern side of the continental tectonic movement dramatically decreasing, a large number of detrital material continuously through Canyon transported to the basin edge, the formation of the late Ordovician early unique characteristics of the terrigenous clastic submarine fan sedimentary system. Ukraine Lalique Fm formed a water slide and debris flow deposits, lashizhong development turbite channel levee deposits. Early Ordovician carbonate facies carbonate deposition mainly, in the late Ordovician Shize of thick terrigenous clastic rocks especially turbidites occupies the main status, composed a complete source, reservoir and cap rocks, has a great potential for oil and gas.