Study on paleogeothermal condition in tectonic development of kyushu based on degree of diagenetic to metamorphic alteration of solid organic matter in the sediments

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The degree of diagenetic to successive various level of metamorphic stages of various geologial sequences in Kyushu are analyzed by the rank of coalification of organic matters in the sediments. Vitrinite reflectance is designated as the rank parameter, of which optical ansotropy is studied for the higher level of alteration. The reflectance values are correlated to the authigenic zeolite facies and metamorphic mineral facies, and also to X-ray analytical data of graphitized coaly matter.The measured data of vitrinite reflectance of dispersed coalified matter from various geological sequences ofvarious sedimentary units have revealed various paleogeothermal pattern in Kyushu. Higher paleogeothermal gradient is found many localities within the Tertiary basins in the inner zone. The thermal effect originated from igneous activitty is more evident and frequent at the northwestern side of the inner zone. In the outer zone, especially in Shimanto Terrain, pre- to syn-kinematic organic metamorphism is identified in Morotuka and Hyuga Groups. Post- kinematic thermal effect is observed in huge olistoliths of Nichinan Group though the effect did not reach to unconformably covered Miyazaki Group. The geological structure of pre-Tertiary Groups is so complicated that it will require further investigation to analyze the more accurate thermal history of Kyushu mountain region, though there are not so abundant dispersed coaly matters in the sediments that suggest various patterns of local thermal effect based on present data.