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Iwatsubodani Formation

Iwatsubodani Fm

Period:

Ordovician

Age Interval:

Ordovician (Tremadocian), (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

The lwatsubodani Fm is completely made up of basaltic rocks. The lithological contrast between the Iwatsubodani Fm and Hitogane Fm indicates a rapid change from mane to felsic magmatism in Ordovician times.

[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:

Metavolcanics

Relationships and Distribution

Lower contact

Regionally, the schematic strat column indicates this as the oldest unit in Fukujitype Gr

Upper contact

Conformably overlies Hitoegane Fm

Regional extent

Hida Gaien Belt- Fukuji-Takayama area (b)

GeoJSON

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Fossils

Age

Shown as Ordovician, hence placed Base of Tremadocian

Age Span:

Beginning stage:

Tremadocian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

486.85

Ending stage:

Floian

Fraction up in the ending stage:

1.0

Ending date (Ma):

471.26

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.