Liqiuwan Fm
Type Locality and Naming
The type section of the Liqiuwan Formation is located at Gaojiawan Village, about 2 km northwest of Guchengfan Town, or about 11 km south of the Liulin Town, Suixian County, Suizhou City (113°13’42”E, 31°25’32”N). It was measured by Northeast Hubei Geological Team in 1986. The Liqiuwan Formation was first published by Du and Yang (1989). The name is derived from Liqiuwan in Guchengfan Village in Liulin Township, Suixian County, Suizhou City, northern Hubei Province. The name was originally appeared in a 1986 manuscript by the Northeast Hubei Geological Team.
Synonym: （立秋湾组）
Lithology and Thickness
The Liqiuwan Formation is an epi-metamorphic clastic sequence, dominated by yellowish green and greyish yellow, silty and phyllitic argillaceous slate, light grey argillaceous slate and greyish black calcareous slate, intercalated with meta-basalt and meta-augitophyre. In the type section, the Liqiuwan Formation is 349 m thick.
Relationships and Distribution
Lower contact
The Liqiuwan Fm is in conformable contact with the underlying Shuangjianshan Fm. The lower boundary of the Liqiuwan Fm is marked by appearance of slate intercalated with meta-basalt and meta-augitophyre at its base.
Upper contact
The Liqiuwan Fm is in conformable contact with the overlying Gaojiawan Fm of Lower Ordovician. The upper boundary is marked by lithological change from slate to limestone at the base of Gaojiawan Fm. The boundary between the Liqiuwan Fm and the Gaojiawan Fm as defined originally by the Northeast Hubei Geological Team lacks evident lithological marker. Chen and Jin (1996) moved the boundary up slightly at the base of striped crystalline limestone in basal part of the Gaojiawan Fm. This revision is followed here.
Regional extent
The Liqiuwan Formation is exposed in the Jiangbei Slope Area of South China Region, restricted to Suizhou City of northern Hubei Province. The thickness of the formation varies from 226 to 290 m.
GeoJSON
Fossils
Only unidentified non-calcifying ostracodomorph arthropod (=archaeocopid ostracoda) is known from the base of the formation.
Age
Depositional setting
Additional Information