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Gomi Formation

Gomi Fm

Period:

Silurian

Age Interval:

Wenlockian (Sheinwoodian), (15a)

Province:
Kurosegawa Belt- Shikoku

Type Locality and Naming

Kurosegawa Belt-central Shikoku

Synonym:

Lithology and Thickness

The lower part of the Gomi Fm consists of basal conglomerate. The main part is composed of welded tuff and intercalated acidic tuff, tuffaceous sandstone, sandstone and mudstone (Yoshikura & Sato 1976).

[Figure 1: Stratigraphy of the Paleozoic of the Kurosegawa Belt in the central part of Shikoku, Southwest Japan (after M. Ehiro et al., 2016)]

Lithology Pattern:

Aus conglomerate

Relationships and Distribution

Lower contact

Regionally, the schematic strat column indicates the next older unit as Mitaki Igneous Complex Fm. The lower part of the Gomi Fm consists of basal conglomerate, which unconformably covers the Yokokurayama Granite (Yasui 1984).

Upper contact

Regionally, the schematic strat column indicates the next younger unit as Fukata Fm. The lower part of the Gomi Fm is overlain by conglomeratic sandstone and sandstone (Yasui 1984).

Regional extent

Kurosegawa Belt-central Shikoku

GeoJSON

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Fossils

A Wenlockian U-Pb SHRIMP age (427 Ma) has been reported from the welded tuff (Aitchison et al., 1996).

Age

Age Span:

Beginning stage:

Sheinwoodian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

432.93

Ending stage:

Sheinwoodian

Fraction up in the ending stage:

1.0

Ending date (Ma):

430.62

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.