Exploration for Oil in Japan: GEOLOGICAL NOTES
Petroleum of the oil fields of Honshu, Japan, occurs in several types of structural traps, in late Miocene and Pliocene sandstone and tuffaceous sand. Interbedded mudstones are considered the probable source rocks. Production from Miocene and Pliocene beds in Hokkaido has been small; Cretaceous beds may yield commercial quantities. Recommendations for future exploration are included.