鄂尔多斯盆地大牛地气田晚石炭—早二叠世地层划分

Stratigraphic division of the Upper Carboniferous-Lower Permian in Daniudi gasfield,the Ordos Basin

根据本溪组和太原组的岩性组合、沉积旋回、标志层和沉积演化史,结合区域地质研究认为,本溪组时代属晚石炭世本溪期,下段为铝土质岩,相当于区域上的铁铝岩段;上段为砂泥岩夹薄煤层,局部夹1～3层灰岩,相当于区域上的半沟段。太原组分为3段,下段为砂泥岩夹薄煤层,相当于区域上的晋祠段,时代属晚石炭世;中段为主煤层、灰岩及与其相当层位的泥岩,相当于区域上的毛儿沟段;上段为砂岩与暗色泥岩互层夹煤层和0～2层灰岩,组成两个旋回,相当于区域上的东大窑段;中、上段时代属早二叠世。

A research into the lithologic assemblage, sedimentary cycle, marker beds, and sedimentary evolution of the Benxi and Taiyuan formations as well as the regional geology reveals that the Benxi Formation was formed during the Late Carboniferous Benxi age. Its lower member consists of bauxitite and is equivalent to the ferrallite interval regionally and its upper member composes of sandstone and mudstone interbeded with thin coal and 1 - 3 local limestone layers and regionally corresponds to the Bangou member. The Taiyuan Formation can be divided into three members. Its lower member is sandstone and mudstone with thin coal interbeds, regionally corresponds to the Jinci member,and its age is the Late Carboniferous. The middle member consists of coalbed,limestone and equivalent mudstone and regionally corresponds to the Maoergou member. The upper member consists of interlayering sandstone and dark mudstones with coal and 0 - 2 limestone interbeds and regionally corresponds to the Dayao member. The age of the upper and middle members is the early Permian.