YuquanNeogene Fm
Type Locality and Naming
Basins offshore NE Zhejiang. The type section is in the 1542–2130 m interval of Longjing No. 1 well located at the continental shelf of East China Sea. It was named and surveyed by Shanghai Comprehensive Marine Geological Party, Ministry of Geology and Mineral Resources in 1981. Geographical coordinates of the type section: 30°10′10″N, 126°05′07″E (GPS).
NOTE: The formation name is a duplication of Permian Yuquan Fm in Heilongjiang Province. Therefore, for this web-based database, "Neogene" is appended to its name.
Lithology and Thickness
It is characterized by the interbedded strata of dark grey mudstones and greyish-white sandstones, intercalated with shales and brown coal beds. The formation has two distinct sedimentary cycles and is divided into two lithological members. For the Lower member, the base is greyish-white pebbly sandstones, the lower part is light grey, fine and very fine sandstones with dark grey or greyish-black shales and carbonaceous shales, bituminous shales, thin coal beds and bituminous coals, and the upper part is dark grey or greyish-green mudstones, shales, carbonaceous shales and bituminous shales with thin-bedded, light grey sandstones and coal beds. The Upper member is alternating beds of dark grey, greenish-grey and brownish-grey mudstones and light grey fine and very fine sandstones, with black carbonaceous shales, bituminous shales and coals, the base of which is greyish-white pebbly sandstones. The coal measures are mainly in this member. The thickness is 588 m.
Relationships and Distribution
Lower contact
The Yuquan Fm is in conformable or partly unconformable contact with the underlying Hailongjing Fm or in unconformable contact with the underlying Eocene Oujiang Fm in Taibei depression.
Upper contact
The Yuquan Fm is in conformable contact with the overlying Liulang Fm.
Regional extent
The Yuquan Fm is widespread in the eastern Zhejiang depression and Taipei depression. In the Changyuan area in their eastern part and the Longjing area in their northern part coal beds are well-developed; in the Yuquan area in their southern part there occur alternating beds of massive sandstone and mudstone with some coal beds; in the Pinghu area in the west the lithology becomes coarse, represented by a large sequence of sandstone with mudstone, coal beds being not developed.
GeoJSON
Fossils
Sporopollen assemblages Rutaceoipollis- Tricolporate and Liquidambarpollenites- Magnastiatites. Foraminifera Spinosigmoilinella compressa and Amomonia sp.. Calcareous nannofossils Sphenolithus heteromorphus. Flagellates Operculodinium wallii, Polysphaeridium zoharyi. Ostracodes are also found in this formation.
Age
Depositional setting
Lacustrine and swampy deposits.
Additional Information