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Yoshiki Formation

Yoshiki Fm


Period: 
Silurian

Age Interval: 
Upper Silurian (Pridoli), (19b)


Province: 
Hida Gaien Belt- Fukuji-Takayama area

Type Locality and Naming

Fukuji—Takayama area (b) is the type locality of this belt (Tsukada et al., 2004).

Synonym:


Lithology and Thickness

Felsic tuffaceous rocks

[Figure 1: Stratigraphic relationship among the rocks of the Hida Gaien Belt (after M. Ehiro et al., 2016)]

[Figure 2: A columnar section of the Muribu and Fukuji successions showing their major lithologies and characteristic layers and blocks (after M. Ehiro et al., 2016)]


Lithology Pattern: 
Volcanic_ash


Relationships and Distribution

Lower contact

Regionally, the schematic strat column indicates the next older unit as Hitoegane Fm

Upper contact

The Yoshiki Fm is largely in fault contact with the surrounding geological units, although it is partly overlain by the Fukuji Fm (Igo 1990)

Regional extent

Hida Gaien Belt- Fukuji-Takayama area (b). The Yoshiki Fm yielding uppermost Silurian radiolarians and coeval zircons with SHRIMP concordant ages of c. 420 Ma (Kurihara 2007; Manchuk et al., 2013a), can be regarded as an equivalent of the Upper Member of the Hitoegane Fm based on its lithological and paleontological similarities (Manchuk et al., 2013b).


GeoJSON

null

Fossils

Yields uppermost Silurian radiolarians and coeval zircons with SHRIMP concordant ages of c. 420 Ma (Kurihara 2007; Manchuk et al., 2013a).


Age 

Shown as Upper Silurian, hence placed Base of 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.