Depositional system of Aershan formation in Tanan Sag of Erlian Basin

摘要

Erlian Basin was composed of many small faulted lacustrine basins in early Cretaceous period. Delta systems were developed and were the most important sandstone reservoir in the gentle slope of faulted lacustrine basins. The paper took an example of Tanan sag, which was one of the most representative faulted sags in Erlian Basin. This paper analyzed the depositional characteristics of ncarshore subaqueous fan systems and fan deltas systems, based on core data, logging data and grain size probability curve. Fan delta-lacustrine deposition system and near shore turbidite fan-lacustrine deposition system were the most developed deposition system in the study area. The lake basin belonged to "narrow basin deep water" type. Mud stone of Deep lake fades and sand stone of fan delta facies in Aershan formation are the best lithology association which would be explored oil and gas in Tanan sag.