Niujiaohe Fm
Type Locality and Naming
The type section of the Niujiaohe Formation lies near the Niujiaohe Village is incomplete with the lower part, termed as Member of Huashan Siliceous rock, unexposed. This member is better exposed at adjacent Huashan-Tongzi section lying between Huashan and Tongzi villages in the Lingtang Township. Both the Niujiaohe and the Huashan-Tongzi sections are merged to form a composite auxiliary section, which is named the Niujiahe and Huashan-Tongzi section (114°17’E, 25°42’N). The composite section lies about 22 km west of the seat of Chongyi County and measured by Jiangxi Regional Geological Survey Team in 1966. The Niujiaohe Formation was first published by Compiling Group for Jiangxi Regional Stratigraphic Scale (1980). The name is derived from Niujiaohe Village in the west of Hengsui Town, the seat of Chongyi County, Ganzhou City, southwestern Jiangxi Province, and was originally appeared in a 1966 manuscript by Wei Xiuzhe from Jiangxi Regional Geological Survey Team. Originally the formation was called Niujiaohe Group, and was lowered in rank as Niujiaohe Formation in a 1988 manuscript by Liu Bangxiu from the Jiangxi Bureau of Geology and Mineral Resources, which was subsequently published by Liu (1997).
Synonym: （牛角河组）
Lithology and Thickness
The Niujiaohe Formation is a clastic sequence. Lower part, called Huashan Siliceous rock Member, dominated by dark grey and greyish black, thin-bedded siliceous slate and siliceous rock, intercalated in part with fine-grained tuffaceous blasto-sandstone and sandy slate. The basal part of the member often bears layers of bone coal. Upper part is dominated by grey and dark grey, thick-bedded blasto-graywacke, tuffaceous blasto-arkose, grey to dark grey, thick- to mega-thick-bedded, fine-grained tuffaceous blasto-feldspathic sandstone, intercalated with black, thin-bedded slate, and dark grey tuffaceous phyllitic slate, containing often siliceous nodules and occasionally silty, argillaceous nodules or silty slate lenses as well. In the composite section, the Niujiaohe Formation is 688.06 m thick.
Relationships and Distribution
Lower contact
The Niujiaohe Fm is in conformable contact with the underlying Laohutang Fm of Ediacaran System. The lower boundary of the formation is defined by the lithological change from the greyish white siliceous rock of Laohutang Fm to black bone coal or carbonaceous slate of the Niujiaohe Fm.
Upper contact
The Niujiaohe Fm is in conformable contact with the overlying Gaotan Fm. The upper boundary is marked by the disappearance of either the carbonaceous siliceous slate or the interbeds of siliceous slate in the top of the Niujiaohe Fm and by the appearance of the thick- to mega-thick-bedded feldspathic quartzose sandstone of the Gaotan Fm.
Regional extent
The Niujiaohe Formation is exposed in the Cathaysia Area of South China Region, distributed in central and southern Jiangxi Province (e.g. Chongyi, Dayu, Yudu, Xingguo, Ruijin, and Taihe counties) and northern, western and occasionally central Guangdong Province (e.g. Ruyuan, Liannan, Nanxion, and Taishan counties). In general, the formation is 1300 to 1500 m, with the maximum thickness of about 2500 m.
GeoJSON
Age
Depositional setting
The early deposits of the Niujiaohe Formation, characterized by sandy flysch rhythmites with turbidite features, represent subtidal stable-water, low-energy environment, whereas the late deposits, characterized by greywacke, feldspathic sandstone, and tuffaceous sandstone, represent deep-water marginal basin setting.
Additional Information