Analysis on source and depositional systems of Yanchang Formation of Upper Triassic of Fuxian exploration area in Ordos Basin

Light,heavy minerals combination and REE characteristics were used to analyze source rock and source direction of Yanchang formation of upper Triassic at Fuxian exploration area in Ordos basin. It is suggested that sediments in this exploration area originate from the northeastern Ordos basin in the period of Yanchang Formation.In addition,it is indicated the source rocks are metamorphic rocks and magmatic rocks of Archean era,Proterozoic era in Yinshan mountain and Daqingshan mountain at the northeast side of Ordos basin.Based on source direction,depositional characteristics and study in the fields,the depositional system of Yanchang Formation of the Upper Triassic in Fuxian exploration area can be divided into two systems.One is delta depositional system and the other is lake depositional system. The evolvement process of delta and lake depositional system are expatiated,respectively.At the same time,it is pointed that the two depositional systems constitute an favorable resource-reservoir-cap rock combination at the space time.