Vitrinite reflectance and thermal structure of the Kuruma, Tedori and Asuwa Groups, central Japan

Abstract

Mean maximum reflectance of vitrinite (R̄max) in the lower Jurassic Kuruma Group ranges from 1.5 to 6.5%, the Middle Jura-Lower Cretaceous Tedori Group 0.9 to 6.5% and the Upper Cretaceous Asuwa Group 0.7 to 5.3%. The lateral variation in R̄max values is due to thermal effect of igneous activities. Large thermal domes are found in the Daira River, middle stream of the Jinzu, and the upper stream of the Kuzuryu. The thermal structure was formed by igneous activities in the Late Cretaceous and Paleogene. -English summary