Quantou Fm

The base of the formation is an unconformable contact marked by purple red and variegated and gray green sandy conglomerate is distinguished from the underlying Jurassic variegated conglomerate.

The top is a conformable contact marked by gray green fine sandstone and sandy mudstone is distinguished from black mudstone of the overlying Qingshankou Fm.

The present formation is widespread but overlain by the Quaternary. Around Dashanzuizi of the Dehui County, Jilin, its outcrops are built up by break red, purple and gray purple sandy conglomerate, gravel-bearing grit and siltstone, measuring 610 m in thickness, lying unconformably on the Jurassic. In Daan-Heidimiao-Huazijing-Sikeji of the Changling area, the Quantou Formation is fine in lithology and ranges from 100 to 120 m in thickness. From Heiyupao of Zhenlai to east of Taobaoxi of the Baicheng area, only the lower part of the formation developed, with a thickness of 60 m, and lies unconformably on the older strata. In the Nongan area, it is generally 700-800 m thick, and more than 2198.5 m down the well No. song-2. In the Yufu County, and Denglouku and Wanjinta of Qian Gorlos there appear conglomerate beds at the base of the formation, and it overlaps the old strata of different ages. On the southeast margin of the basin and in Jiutai and the Jilin small area, it is also exposed where it is relatively coarse in lithology and is less than 1000 m in thickness. In Heilongjiang, it is mainly distributed in the area south of the line linking Suiling, Beian, Dedu and Nahe. In the Lindian-Mingshui area of north Heilongjiang, the first member of the Quanshui Formation is dominated by variegated sandy conglomerate with sandstone and mudstone and overlaps the base of the basin, ranging from 78 to 440 m in thickness, locally in excess of 191.5 m. In the Daqing and Putaohua central depressions, the Quanshui Formation is in conformable contact with the Denglouku Formation, ranging from 78 to 440 m in thickness. In the depression of the uplift zone, it is seen to contain gypsum lumps and is in conformable or disconformable contact with the Denglouku Formation. The second member of the Quantou Formation extends slightly to the northern part of the basin. In the Keshan, Lindian and Mingshui area, it is generally 80-140 m thick and thins out towards the eastern and western sides and overlaps the base of the basin in the Keshan area; it is 119-284 m in Daqing and Putaohua, more than 320 m in Chaoyanggou-Fuguangtun of east Heilongjiang and less than 100 m in Chaoyanggou. The third and fourth members covered a larger area when deposited; more than 450 m at maximum in the Keshan County, decreasing in thickness towards both the eastern and western sides and mostly overlapping the strata prior to the Mesozoic towards the margins of the basin; in Hulan Ergi-Tailai in the western part of the basin, their lower parts are mostly intercalated with massive breccia and mudstone, with small amounts of conglomerate, ranging from 68.5 to 200 m in thickness; becoming thinner from east to west, 400-700 m thick in the central part, 529 m at maximum in the Putaohua area, quite thin in Renminzhen, only 282.5 m; in the eastern part of the basin, the third member is generally 340-450 m thick; the fourth member in the northern part is mainly built up by purple red and small amounts of gray green sandy mudstone, generally 60-80 m in thickness; in the western part the two members are represented by variegated mudstone and sandy mudstone interbedded with fine sandstone and grit, and thin out from east to west, 80-122 m thick in the central part; and in the eastern part, the two members are about 100 m thick.