Chonomori Fm
Period:
Triassic
Age Interval:
Late Triassic (Carnian-Norian), (8e)
Province:
South Kitakami Belt-Western Sub-belt
Type Locality and Naming
Shizugawa (Shizukawa)-Hashiura Sub-belt; Shizugawa area
Synonym:
Lithology and Thickness
It consists of alternating beds of sandstone and mudstone.
Lithology Pattern:
Sandy_claystone
Relationships and Distribution
Lower contact
The Chonomori Fm conformably covers the Shindate Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Saragai Gr
Regional extent
Shizugawa (Shizukawa)-Hashiura Sub-belt; Shizugawa area
GeoJSON
null
Fossils
Naumann (1881) reported an occurrence of bivalve fossil Monotis from the Chonomori Formation, which is the first report of the Triassic fossils from Japan. The Chonomori Formation yields a rich Monotis fauna in association with ammonoids Placites and Arcestes (Shimizu & Mabuti 1932; Onuki & Bando 1958; Nakazawa 1964; Ando 1987)
Age
Late Triassic (Carnian-Norian)
Age Span:
Beginning stage:
Carnian
Fraction up in beginning stage:
0.5
Beginning date (Ma):
232.15
Ending stage:
Norian
Fraction up in the ending stage:
1.0
Ending date (Ma):
205.74
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Moreno, T., Wallis, S., Kojima, T. & Gibbons, W. (Eds) 2016. The Geology of Japan. Geological Society. London. 1-24.