Xiadaminshan Fm
Type Locality and Naming
A type section was not given. The Xiadaminshan Formation is a composite from various reference sections. It was named by Ning Qisen et al. in 1958.
Lithology and Thickness
Tuff, volcanics, limestone, sandstone: It is characterized by variegated volcanic clastics, carbonates and terrestrial clastics with various thicknesses ranging from tens to 200 meters.
The Lower part, as characterized by Linchang section at Zadunhe River, near Mianduhe of Great Hinggan Mts, is composed of purplish-red tuffaceous lava, bioclastic limestone, white marble and gray green tuffaceous sandstone.
At the left bank of Zadunhe River, the lithologies of the Formation are more complex including volcanic breccia, quartz porphyrite, tuff, tuffaceous sandstone and calcareous sandstone.
Relationships and Distribution
Lower contact
The lower boundary of the Formation is unclear. But next older formation regionally is the Huoboshan Fm conglomerate and sands.
Upper contact
Conformably overlain by the Shandgaminshan Fm volcanic ash
Regional extent
GeoJSON
Fossils
Linchang section at Zadunhe River, near Mianduhe of Great Hinggan Mts, contains:
coral Cladopora sp., Thamnopora sp., Penekiella sp.,
brachiopoda Productella sp., Cyrtospirifer sp., and
conodont Polygnathus varcus.
At the left bank of Zadunhe River the Formation yields coral Phillipsastrea sp., Pexiphyllum sp., Barrandeophyllum sp.
Age
Depositional setting
Additional Information