Paleogene and older Sediments

Overview

Sediments older than Paleogene produced in an island arc formed by subduction of ocean plates under the east margin of the Eurasian continent. These sediments were deposited before formation of a back-arc basin (the Japan Sea), and most of them were formed at continental shelves with a minor amount of fore-arc basin sediments.

Blue: Paleogene, Red: Cretaceous-Jurassic-Triassic, Green: Permian-Carboniferous-Devonian- Silurian-Ordovisian. These sediments overlie unconformably the basement of the Japan Island Arc such as accretionary complexes and plutonic rocks.