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Senjyogataki Formation

Senjyogataki Fm


Period: 
Silurian

Age Interval: 
uppermost Silurian (Pridoli), (8b)


Province: 
South Kitakami Belt- Miyamori-Hayachine-Kamaishi district

Type Locality and Naming

Synonym:


Lithology and Thickness

It consists from base to top, of basalt and dolerite, tuff and alternating beds of tuffaceous and siliceous mudstones, and mudstone (Okami et al., 1987).

[Figure 1: Stratigraphy of the Palaeozoic of the South Kitakatmi Belt, NE Japan (after M. Ehiro et al., 2016)]


Lithology Pattern: 
Siltstone


Relationships and Distribution

Lower contact

Regionally, the schematic strat column indicates the next older unit as Orikabeloge Fm. In the Kamaishi district the uppermost Silurian-Upper Devonian Senjyogataki Fm rests on the Kentosan Unit Fm (equivalent of the Kagura Unit Fm) of the Hayachine Complex, although their stratigraphic relationship is unclear.

Upper contact

Regionally, the schematic strat column indicates the next younger unit as undivided Devonian Fm

Regional extent


GeoJSON

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Fossils

The tuffaceous-siliceous mudstone yielded latest Silurian (Pridolian) (Suzuki et al., 1996) to Early Devonian radiolarians (Umeda 1998a), and the uppermost part of the formation contains the Late Devonian (Famennian) plant Leptophloeum (Okami et al., 1987).


Age 

uppermost Silurian (Pridoli)

Age Span: 

    Beginning stage: 
Pridoli

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
422.73

    Ending stage: 
Pridoli

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
419.00

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.