Yuelong Fm
Type Locality and Naming
It was named by the Regional Survey Party of Hunan Province in 1976. The naming section is located in the vicinity of the Yuelong Automobile Station of Liuyang County, Hunan Province.
Synonym: （跃龙组）; The Yuelong Formation defined in the section at the Fengjiachong area of Liling County is correspondent to the Shixijiang Fm created by the Hunan No. 3 Coal Prospecting Party and Chen Jinhua (1976). So, in the eastern Hunan the former term has been used, while in southwestern Hunan the latter term is advisable to be used.
Lithology and Thickness
Lower part is composed largely of yellow-green silty mudstones, intercalated with siltstones and a small amount of arkosic quartz-sandstone. Upper part is alternating layers of purple silty mudstones and yellow-green silty mudstones, intercalated with arkosic quartz-sandstones and marl lenses, with a total thickness of the strata being of 564 m.
Relationships and Distribution
Lower contact
Its basal part is in a conformable contact with the underlying Gaojiatian Fm
Upper contact
No top has been found.
Regional extent
It is distributed mainly in the Yaolong area of Liuyang County, Zhetangpu area of Hengshan County, Hengyangzhou City, Huangnitang, Shajing and Guanyintan areas of Qiyang County, and Huangyangsi and Fengjiachong areas of Liling County. In the Fengjiachong area of Liling County the formation represents essentially an alternating layer of arkosic quartz-sandstones and siltstones in association with mudstones, yielding a small amount of bivalve and plant fossils, with a thickness of 295 m. There are no great variations in its lithology. Except for the above-mentioned two localities where there is a greater thickness of the formation, in the rest regions the thickness of the formation varies commonly in a range from 100 m to 200 m.
GeoJSON
Fossils
It yields bivalve fossils as represented by the Cuneopsis-Pseudocardinia assemblage important members of which comprise Cuneopsis johannisboehmi, C. cf. sichuanensis and Pseudocardinia kweichouensis; “conchostracan” fossils as represented by Eosolimnadiopsis fuanensis; Ostracod fossils as represented by Darwinula giganimpudica, D. lufengensis, D. aff. sarytirmenensis, D. cf. oblonga and Metacypris parva; and plant fossils as represented by Equisetum sp., Neocalamites sp. and Brachyphyllum sp.
Age
Depositional setting
The formation is interpreted as lacustrine deposits.
Additional Information