Sedimentary characteristics and model for the sandstones and conglomerates in the 4th member of the Palaeogene Shahejie Formation, northern Dongying depression, Shandong

Sedimentary characteristics, genetic types and sedimentary model are treated in detail for the sandstones and conglomerates in the 4th member of the Palaeogene Shahejie Formation, northern Dongying depression. Sedimentary structures in the sandstones and conglomerates are common, including massive bedding, graded bedding, parallel bedding, superimposed scour structure, cross bedding, deformational structure, rip-up clasts, load cast and flame structure. The clastic grains are primarily derived from promixal sources, and non-sorted to moderately sorted and angular-subangular to sub-rounded. The lithofacies consist of the massive-bedded conglomerate facies, graded-bedded conglomerate facies, graded-bedded sandy conglomerate facies, cross-bedded gravelly sandstone facies, parallel-bedded gravelly sandstone facies, massive-bedded gravelly sandstone facies, massive sandstone facies, parallel-bedded sandstone facies, massive-bedded sandstone facies, deformationalbedded sandstone facies, rip-up deformational sandstone facies, and thin-bedded lenticular or flaser bedded sandstone facies. During the deposition of the 4th member of the Palaeogene Shahejie Formation, the nearshore submarine fan, sublacustrine fan and fan delta sandstones and conglomerates are accentuated in northern Dongying depression. The examination of the sedimentary characteristics and model for the 4th member of the Palaeogene Shahejie Formation, northern Dongying depression in this paper is important to the understanding of the sandstone distribution and future exploration of hydrocarbons in the study area.