Qingshankou Fm

The base of the formation marked by 20 m gray black mudstone with black brown oil shale is bounded by the underlying Quantou Fm marked by gray green mudstone. The contact is conformable.

The top marked by gray mudstone is distinguished from the overlying Yaojia Fm marked by grayish brown calcareous siltstone and fine sandstone. The contact is conformable.

It is widespread in the Songliao basin. In the Baichengzi area of Jilin, it is bounded by the line linking Baicheng-Shuanggang-Shengli and gradually thins out westward. It is represented by grayish green siltstone, fine sandstone, gravel-bearing sandstone, and small amounts of granule conglomerate and brownish red mudstone, with a maximum thickness of 200 m. in the area south of the line linking the Liangjia railway station, Heidimiao and Fulongquan of Changling, there appear a lot of clastic rocks, and quite a lot of brownish red and grayish green mudstone are intercalated in the middle and upper parts of the formation. To the west of the line linking Yushu, Changchun and Gongzhuling , it is dominated by brownish red mudstone. In Huaide and Shuangchengbao, it becomes coarser in lithology, without oil shale, generally measuring 300 m in thickness. The formation outcrops in Wukeshu of the Yushu County, Qingshankou of the Nongan County, Denglouku of the Qian Gorlos, Erdaogou of the Jiutai County, and Shangendi of the Huaide County. The first member is basically the same in lithology throughout Heilongjiang and increases in the amount of sandstone, and becomes coarser in grain size, where appear red mudstone. The formation is generally 30-80 m thick towards the margin of the basin in the northern part. The second and third members vary considerably both in lithology and thickness, and are built up by gray and grayish green mudstone and sandy mudstone with siltstone and fine-grained calcareous sandstone. In Nangnangxi-Taikang in the western part, ostracod limestone is observed and there appear red mudstone in the northern and eastern parts. The formation is 400-500 m in the central depression, 130-170 m in the northern part, 240-323 m in the central depression near the northern part, 130-160 m in Keshan-Beian towards north, and generally 53-124 m in the western part.