Carboniferous-Permian tectonic and stratigraphic framework of eastern Inner Mongolia as well as adjacent areas and its formation environment

Stratigraphic formation and its distribution are controlled by both tectonic background and palaeo-geographical conditions. By adopting several stratigraphic methods, mainly the tectono-stratigraphy method, and combining the study of major sections with the review of data available, this paper has divided eastern Inner Mongolia and its adjacent areas into Carboniferous-Permian stratigraphic regions and established a tectono-stratigraphic framework. The study area is divided into three stratigraphic regions by two tectonic lines. The southern side of the Xilamulun fault, i.e., the Huabei stratigraphic region, is named Kangbao-Chifeng district characterized by outcropped strata of continental margin depressions and an intracontinental rift. The northern side of the Chaganaobao-Arongqi-Heihe line, i.e., the Xing'an stratigraphic region, belongs to the Siberia Plate. The Dongwu-Longjiang district contains strata of continental margin depressions and an intracontinental rift, and strata of the Ergun district show features of continental margin depressions and rifts. Lying between the two lines, the accreted zone can be naturally divided into three stratigraphic districts, namely Xilin Gol district, Horqin district and Song-Liao district, which are characterized by the development of complex environments composed of multi-island oceans, marine troughs and residual troughs. Moreover, through discussing ages and facies of lithologic formations, the tectono-stratigraphic framework can reflect both the tectonic pattern and environment changes.