Sifangtai Fm
Type Locality and Naming
Songliao Basin. Horinchi (1937) erected the Sifangtai bed. The Songliao Petroleum Exploration Team (1959) renamed it as the Sifangtai Formation. The type locality for the designation is at Sifangtai of the Suihua City of Heilongjiang. The reference section is down the well No.ku-3 of the Mongolian Autonomous County of Dorbod of Heilongjiang. Upper formation (6 of 7) in the Songhuajiang Gr.
[Figure: Sifangtai Formation at Sifangtai section in Jujiatun Village, Suihua City]
Lithology and Thickness
The Sifangtai Formation is represented by a set of variegated sandy mudstone. Lower part is dominated by brown red massive sandstone and brown red and gray green massive mudstone with siltstone and boulder-clay. Upper part is brown red and grayish green massive sandy mudstone with calcareous nodules. It is 160 m thick.
Relationships and Distribution
Lower contact
Its base is a unconformable contact marked by variegated massive mudstone is distinguished from brown red mudstone of the underlying Nenjiang Fm.
Upper contact
Its top is a conformable contact marked by brown red sandy mudstone is distinguished from grayish green siltstone of the overlying Mingshui Fm.
Regional extent
The present formation mainly occurs in the central and western parts of the Heilongjiang basin, and has been disintegrated or even free of deposition in the eastern part of the basin. In the Heidimiao-Qianan area of Jilin, it is dominated by gray green and brown red mudstone and silty mudstone, forming cyclothems together with gray white and gray green siltstone and fine sandstone, locally with sandy conglomerate beds, ranging from 200 to 400 m in thickness, decreasing in thickness towards both sides. In the Baicheng area, it is generally 80-150 m thick and is thin in the east and thick in the west. In Heilongjiang, it is 0-283 m thick in the central depressed area, 30-60 m in the western part and is thick in the east and thin in the west, 40-89 m in the northern part, 0-125 m in the eastern part. It lies unconformably on the underlying Nenjiang Formation, except in some parts of the central depressed area.
GeoJSON
Fossils
The formation yields ostracods Talicypridea amoena, Cypridea cavernosa, C. apiculata, Candoniella suzini; in the Gulong and Changling areas bivalves Protelliptio (Plesielliptio) sungarianus; down the borehole No.nan-47 Pseudohyria arilica, P. aff. gobiensis; down the borehole No.qian-3 sporopollens represented by the Schizaeoisporites-Callistopollenites- Tricolporopollenites assemblage.
Age
Depositional setting
It belongs to shallow and shore facies deposition.
Additional Information