The depositional systems and palaeogeography of the Lower Jurassic Fuxian Formation in the Ordos Basin

The Ordos Basin is one of the largest Mesozoic coal bearing basins and continental petroleum basins in China. The Fuxian Formation represents the earliest Jurassic sedimentary strata in the basin developed upon the denudational surface generated during the Indosinian orogeny, and is overlain unconformably upon the underlying Triassic Yanchang Formation. The sediment thickness and lithology are highly variable. The deposition here is manifested in filling, and the depositional systems consist of the alluvial fan and fluvial sediments, where the channel facies has more potential as oil and gas reservoirs if the cover of the channel sediments in the formation are favourable.