Luanshigou Fm
Type Locality and Naming
Central-westernmost Hubei. The Luanshigou Fm was named by Hubei Party of Regional Geological Survey in 1974. The type section is in Honghuaxigou, Shennongjia Forest District, Hubei Province. Lower formation (3 of 11 in Lexicon) of Shennongjia Gr.
Synonym: （乱石沟组）, Heiwan Member (Yulongting Fm)
Lithology and Thickness
The Luanshigou Fm is dominated by grey medium-thick-bedded oolitic algae-mat and siliceous-banded dolomite and then stromatolite-bearing lithic tuffaceous dolomite, pebbly dolomite, sandwiched with dolomitic breccia, pebbly quartz sand stone, trachyte, ferruginous slate, and bedded hematite. The formation contains oolitic grains, stromatolites and syngenetic clasts, as well as the cross-bedding, ripple marks, scouring surface, disturbed bedding, desiccation crack and pseudocrystal of salt. The formation is 1045-1457 m thick.
Relationships and Distribution
Lower contact
It is in conformable contact with the underlying Dayanping Fm.
Upper contact
The top is conformably overlain by the Dawokeng Fm.
Regional extent
Central-westernmost Hubei. The Luanshigou Fm is exposed in Jiuchong, Songluo, Kushui river, and on west slope of Dashennongjia Forest District.
GeoJSON
Fossils
The major taxa of stromatolites in the formation are Stratifera umdata, Cryptoxoon giganteum,Colonnella f., Kussiella f., Scopulimorpha f.. The microalgae are Gunflintia septata, Forrimoniloides invlvens, Huroniospora sp.. The microplants are Leiopsophosphaera apertus, L. minor, L. densa, Trachysphaeridium simplex, T. minor, T. rugosum, T. hyalinum, Polyporata obsoleta etc.
Age
Depositional setting
Additional Information