Ono Fm
Type Locality and Naming
Synonym:
Lithology and Thickness
Basic tuff, Shale. (Further divided into Oh1, Oh2, Oh3 members (Minato et al., 1979). The Oh1 Member, which has yielded Pridolian radiolarians (Umeda 1996b), is a slump bed which incorporates variously sized clasts of granite, arkose and limestone in a tuffaceous and siliceous mudstone. These clasts are lithologically similar to the underlying Hikami Granite and basal arkose and limestone of the Kawauchi Formation, respectively. The Oh2 Member is composed of acidic tuff and alternating beds of acidic tuff and tuffaceous-siliceous mudstone, and the Oh3 Member similarly consists mainly of tuff with subordinate amount of tuffaceous sandstone and mudstone.
[Figure 1: Stratigraphy of the Palaeozoic of the South Kitakatmi Belt, NE Japan (after M. Ehiro et al., 2016)]
Relationships and Distribution
Lower contact
Regionally, the schematic strat column indicates the next older unit as Kawauchi Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Nakazato Fm
Regional extent
GeoJSON
Fossils
The Oh1 Member, has yielded Pridolian radiolarians (Umeda 1996b).
Age
Depositional setting
Additional Information