Abstract:

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 divi-ded 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.

Key words: Upper Carboniferous Benxi Formation, Upper Carboniferous-Lower Permian Taiyuan Formation, Daniudi gasfield, Ordos Basin