Luoquan Fm
Type Locality and Naming
West Henan. The Luoquan Fm was named by Liu Chang'an and Lin Weixing in 1961. The type section of Luoquan Fm is in Luoquan Village, Manchuan, Linru County, Henan province (E112°45′00″; N34°01′00″). It was re-measured by Guan Baode and Geng Wuchen in 1988.
And the reference section is in Miaocun village in Yiyang County, Henan Province.
Synonym: （罗圈组）, Linru moraine Fm (临汝冰碛层); Fengtai conglomerate Fm (凤台砾岩); Zhengmuguan Fm (正目观组)
Lithology and Thickness
The Luoquan Fm is dominated by a suite of detrital rock and mudstone with a total thickness of 180 m. The pebbles (debris) are dominated by clasts of the underlying strata including quartzose sandstone, siltstone, and secondly, cherty rock, dolomitic limestone, shale (or mudstone). The detrital rocks of glacial-fluvial origin bear occasionally metamorphic clasts (biotite gneiss, marble etc. which does not derive immediately from the underlying strata) of which degree of roundness is variable, dominated by subangular and angular, then subrounded shape, whereas the other clasts in the detrital rock of glacial-fluvial origin are dominated by subrounded to rounded. The surfaces of pebbles generally bear glacial features, such as polished surface, glacial striations, impressions, pressure fissure, lunate fracture and cracks, etc. The matrix of the tillite is dominated by quartzose sandstone, secondly carbonate rock or debris (composition similar to pebble) and minor feldspar etc.
[Figure: The Luoquan Formation (photos by Kuang Hongwei, 2017). a,b- The section of the Luoquan Formation; c,d- The ice flow surface of the Luoquan Formation; e- Tillit; f- The Luoquan Fm is unconformable onto the underling Beidajiang Fm.]
Relationships and Distribution
Lower contact
The basal part of the Luoquan Fm is light gray massive pebbly muddy sandstone and rests disconformably on the underlying Dongjia Fm. However, the Luoquan diamictite covered different horizons and different rocks with bottom (basal) moraine on the Bingmagou Fm sandstone, Sanjiaotang Fm sandstone and some carbonate rocks of the Huanglianduo Fm or Luoyukou Fm. Even deposited on the Cuizhuang Fm shelly siltstone.
Upper contact
The upper part of red purple to dark purple silty shale is conformably overlain by the Dongpo Fm
Regional extent
West Henan. It is distributed on the north slope of east Qinling Mountain, from Huainan of Anhui Province, going westward to Queshan, Wuyang, Lushan, Linru, Yiyang and Lingbao of Henan Province, then to Yongji of Shanxi Province and Luonan of Shaanxi Province.
GeoJSON
Fossils
The matrix of the Luoquan Formation yields microplants: Leiopsophosphaera infriata, L. pellucida, Trachysphaeridium rugosum, T. incrassatum, T. planum. T. aff. laminaritum, Stictosphaeridium sp., Tasmanites sp., Laminarites antiquissimus, Taeniatum crassum, Trematosphaeridium holtehdahlii, T. minutum etc.
Age
Depositional setting
Additional Information