Huolongmen Fm
Type Locality and Naming
No type section was given. It was named by Zhao Guisan et al. in 1957
Lithology and Thickness
Siltstone, claystone. It is dominated by shallow-marine deposits, characterized by gray siltstone and slate intercalated with limestone lenses. In the base are pebble-bearing sandstone or thin-bedded sandy conglomerate. The formation has usually undergone low-grade metamorphism. The formation is 121 to 184.5 m in thickness.
Relationships and Distribution
Lower contact
The formation overlies conformably on the Jinshui Fm and shows no considerable changes in lithology along strike. The main difference between the two formations is that the Jinshui Fm contains more chlorite slate. The bed of pebble-bearing sandstone between these two formations is a marker bed to separate them.
Upper contact
Conformably overlain by Dean Fm (according to that entry)
Regional extent
Shown on strat-column chart as also being in Central Heilongjiang (overlying Xiaheilonggong Fm)
GeoJSON
Fossils
Fossils are abundant and dominated by brachiopods: Gladiostrophia kondoi, Coelospira dongbeiensis, “Parasperifer” aff. gurjevskiensis, Howwellella amurensis, Rhytistrophia beckii, Fallaxispirifer pseudofallax. etc., and is associated with minor trilobites, bivalve and bryozoan.
Age
Depositional setting
Additional Information
Was apparently omitted on initial strat-column chart