Sakamotozawa Fm
Type Locality and Naming
Synonym:
Lithology and Thickness
It consists of basal conglomerate, sandstone and alternating beds of sandstone and mudstone in the lower part, massive limestone with mudstone in the main part and sandstone and mudstone in the uppermost part (Kanmera & Mikami 1965a)
[Figure 1: Stratigraphy of the Palaeozoic of the South Kitakatmi Belt, NE Japan (after M. Ehiro et al., 2016)]
Relationships and Distribution
Lower contact
The formation unconformably overlies the Carboniferous Nagaiwa Fm or its equivalents but without any notable structural break, except in the Setamai district where it progressively oversteps various horizons of the Carboniferous from the uppermost Shittakasawa Fm to the Nagaiwa Fm (Saito 1968).
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Kanokura Fm
Regional extent
Equivalent strata of the Sakarmotozawa Formation in other areas also comprise basal conglomerate or sandstone, sandstone, mudstone and limestone, although the amounts of these different components vary from place to place (Ehiro 1989, 2016)
GeoJSON
Fossils
The Sakamotozawa Formation and its equivalents yield a rich fauna of fusulinoideans and corals. Kanmera & Mikami (1965b) established five fusulinoidean zones- the Zellia nunosei, Monodiexodina langsonensis, Pseudofusulina vulgaris, P. fusiformis and P. ambiguta zones.
Age
Depositional setting
Additional Information