• Journal of Korea Far Infrared Association
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• s.13
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• pp.53-56
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• 2002

• The Korean Journal of Petroleum Geology
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• v.2 no.2 s.3
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• pp.83-90
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• 1994

Thermal maturation and diagenesis of the Gyeongsang Supergroup in the Euiseong area are studied by means of organic geochemical techniques and illite crystallinity. Black mudrocks of the Singdong Group contain organic matter of $0.5{\~}2{\%}$ derived from higher plants, being compared to type Ⅲ. Thermal maturity of organic matter reached dry gas generation phase. Tmax by Rock Eval pyrolysis varies between $578^{\circ}C$ and $593^{\circ}C$ regardless of stratigraphic position and localities, and vitrinite reflectance is about 2.9 and $3{\~}4{\%}Ro$ in the Jinju and the Nagdong Formations, respectively. Vitrinite reflectance measurements indicate that the maturation is mainly due to burial and partly to be affected by post-depositional intrusions. Illite crystallinity values from the Nagdong, Hasandong, Jiniu Formations and part of the Iljig Formation are plotted around the boundary between diagenesis and anchizone, indicating dry gas generation stage. However, the values are not dependent on stratigraphic position. The values from the Iljig, Hupyeongdong, Geomgog, and Sagog Formations fall into the range of anchizone, probably resulted from the post-depositional intrusions which occur locally. Both organic geochemical and illite crystallinity data indicate thermal maturation stage of dry gas generation. Diagenesis of the Gyeongsang strata is mostly controlled by burial, and partly affected by post-depositional intrusions. Paleotemperature of the Sindong Group is estimated at around $200^{\circ}C$ on the basis of illite crystallinity.