Ishiwaritoge Fm
Period:
Triassic
Age Interval:
Middle Triassic (Bajocian), (8h)
Province:
South Kitakami Belt-Central Sub-belt
Type Locality and Naming
the Karakuwa-Oshika Sub-belt
Synonym:
Lithology and Thickness
It is composed of conglomerate with alternating beds of sandstone and mudstone and also thins towards the west and south (Ehiro 1974). The conglomerate is dominated by granitic pebbles to boulders, thought to be derived from the pre-Silurian Hikami Granite (Kane 1959). It is 20-150 m thick.
Lithology Pattern:
Aus conglomerate
Relationships and Distribution
Lower contact
Regionally, the schematic strat column indicates the next older unit as Tsunakizaka Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Mone Fm
Regional extent
GeoJSON
null
Fossils
Age
Shown as Middle Triassic-lowermost Cretaceous hence placed Base of Bajocian
Age Span:
Beginning stage:
Bajocian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
170.90
Ending stage:
Bajocian
Fraction up in the ending stage:
1.0
Ending date (Ma):
168.17
Depositional setting
It is deposited in a fluvial-alluvial environment (Takizawa 1985)
Depositional pattern:
Additional Information
Compiler:
Moreno, T., WALLIS, S., Kojima, T. & Gibbons, W. (Eds) 2016. The Geology of Japan. Geological Society. London. 1-24.