Provenance Analysis of the Yan'an Formation in Mid-Jurassic at the Southeast Area of Ordos Basin

The Yan'an Formation in the southeast area of the Ordos basin is an important oil-bearing series of middle Jurassic.Features of parent rocks,provenance and relevant tectonic setting of sediments of the Yan'an Formation in the southeast area of the Ordos basin have been studied by many methods,such as the analyses of clastic rock components,heavy minerals contents,cathodoluminescence of quartz,REE characteristics of mudstone,and field paleocurrent survey.The study shows that the dominant paleocurrent and sediment source during the deposition of Yan'an Formation came from the directions of northeast and northwest.The mother rock is mainly granitoids,gneiss system and epi-metamorphic rocks in the Achaean and early proterozoic from northern Yinshan,northeastern Lvliang mountain and northwestern Alashan areas,where had been inferred as a stable provenance for the basin deposition since Late Paleozoic.This provenance study of Yan'an Formation is of great significance for further oil-gas exploration in the basin and tectonic research in the peripheral of Ordos Basin.