Permalink : http://hdl.handle.net/2115/36678

Thirteen kerogens separated from the siltstone of the Oligocene Poronai Formation were analysed to examine the thermal alteration effect by the basalt intrusion. This intrusion gave a drastic decrease of kerogen content in the siltstone within a meter from the contact. At the proximity of the basalt the increase of H/C and of n-alkanes generated from the kerogen by laboratory pyrolysis suggests hydrogenation to the kerogen by superheated steam provided from the igneous intrusion.