LITHOFACIES PALEOGEOGRAPHY OF THE CRETACEOUS IN THE JUNGGAR BASIN

Based on the outcrop, drilling, logging and seismic data, the lithofacies paleogeographical cha racteristics of the Cretaceous in the Junggar Basin were analysed. The basin developed alluvial fan, braided stream, alluvial plain, delta, shore shallow lake and semideep lake sedimentary facies. Lithologically, the alluvial fan was dominated by sand conglomerate, the braided stream by gravelly sandstone and moderate fine sandstone, the delta by microsandstone and siltstone, and the allluvial plain, the shore shallow lake and the semideep lake by mudstone. Alluvial fan, braided stream and alluvial plain deposits were developed in basal conglomerate layers. During the sedimentary periods of the Qingshuihe Group, the Hutubihe Group and the Shengjinkou Lianmuqin Group, delta, shore shallow lake and semideep lake deposits were developed, And braided stream and flood plain deposits were developed in the sedimentary period of the Donggou Group. The delta sandbodies of the Qingshuihe Group and the Hutubihe Group were the favorable reservoirs and exploration targets of the Gretaceous in the basin.