Zhougongshan Fm
Type Locality and Naming
It was named by the Petroleum Prospecting Party of Anhui Province as the “Zhougongshan Group” in 1960. The naming section is located at the Zhougong Mts of Feixi County, Anhui Province, with its reference section being situated in the vicinity of Juxin Village of Feixi County.
Synonym: （周公山组）
Lithology and Thickness
The lower part of the lower member is composed of purple siltstones and yellow-green arkosic quartz-sandstones, intercalated with pebble-bearing gritstones, siltstones, mudstones and sandy limestones, with a thickness of 762 m; the upper part of the lower member is composed of variegated siltstones and sandstones, with a thickness of 576 m. The lower part of the upper member is composed of alternating layers with different thickness of purple siltstones, sandstones and sandy conglomerates, with a thickness of about 284 m; the middle part of the upper member, of an alternating layer of red thick-bedded sandy conglomerates, arkosic quartz-sandstones in association with siltstones, with an increase in the amount of coarser clastics downwards, and with a thickness of about 245 m; and the upper part of the upper member, of an alternating layer of light-purple sandstones, intercalated with siltstones, with a thickness of 234 m. The total thickness of the formation is of 2100 m.
Relationships and Distribution
Lower contact
Its basal part is in a disconformable contact with the underlying Fanghushan Fm
Upper contact
No directly covering strata above the formation. Regionally, the schematic strat columns and Cretaceous Lexicon indicates the next younger unit is the Fenghuangtai Fm of earliest Cretaceous, implying absence of the Late Jurassic.
Regional extent
It is distributed mainly in the Lu’an and Hoshan Mts areas of Huinan City, as well as in Feixi County. On the surface in the vicinity of the Lu’an region, and in the drilling wells in the Wuji and Cidun areas of Hoqiu County there is found only the upper member of the formation, with a thickness of about 294 m.
GeoJSON
Fossils
At a quarry in the Lianggang area of the western suburb of Hefei City there are found plants as represented by Cupressinocladus sp. in the formation.
Age
Depositional setting
The formation belongs to fluvial-lacustrine deposits.
Additional Information