Nakazato Fm
Type Locality and Naming
Synonym:
Lithology and Thickness
Shale. (Further divided into N1, N2, N3 and N4 members (Minato et al., 1979). The N1 Member consists mainly of basic tuff and lapilii tuff in association with mudstone; the N2 Member is composed of alternating beds of acidic tuff and mudstone; and the N3 Member comprises alternating beds of sandstone and mudstone, a part of which is tuffaceous. The lower part of the N4 Member consists of sandstone and pebbly sandstone, and the upper part of it consists of sandstone and mudstone with subordinate amounts of tuff.
[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 Nakazato Fm conformably overlies the Ono Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Hikoroichi Fm
Regional extent
GeoJSON
Fossils
The N3 Member has yielded Middle Devonian trilobites (Kobayashi & Hamada 1977; Minato et al., 1979) and Middle Devonian (Givetian) radiolarians (Umeda 1996b).
Age
Depositional setting
Additional Information