Depositional Characteristic of Permo-Carboniferous System from Yingen-Ejinaqi and Their Surrounding Areas,Inner Mongolia,China and it Implications for Petroleum
ZHAO Xingmin, CHENG Dengchao, DENG Jian Institute of Mineral Resources, CAGS, Beijing, 100037
A study on depositional characteristics is very important for petroleum geology exploration. Relatively less research and exploration here, however, have been made due to their deeply-buried, geological-complicated and bad-natural conditions, and etc. Therefore, this study focused on the depositional characteristics of Permo-Carboniferous systems by taking full use of the outcrops in surrounding area and detailed investigation for nearly 30 profiles. The results show that Permo-Carboniferous formation comprises mudstones, sandstones, sandy conglomerates, carbonate rocks, volcanic rocks (or pyroclastic rocks), etc., accompanied by a large amount of marine organism. Dark mudstone dominates of the Permo-Carboniferous formation, and is a potential source for hydrocarbon and cap rocks. The main reservoirs of the Permo-Carboniferous consist of widely-developed volcanic rocks (or pyroclastic rocks), lenticular and silicated carbonate rocks, and minor sandstones and sandy conglomerates. The lithological compositions and distribution pattern also reveal that frequent faulting and strong volcanism concurring in the study area, along with deep water body are highly advantageous to generation of hydrocarbon. The main depositional types contain neritic shelf, open coast, carbonate platform, braided delta, fan delta and volcanic eruption etc, among which both neritic shelf and barrier coast form the source rocks and cap rocks, and other facies make up reservoirs for oil and gas respectively. This provides advantageous conditions of oil and gas for the Permo-Carboniferous systems.