In the marginal areas of the Asian continent, the Paleogene and Miocene coal-bearing formations are sporadically distributed. In some areas, particularly in the sea regions, their equivalents are possibly explored for oil and gas. The basins mainly formed as tectonic depressions, and are filled with fluvial to marine clastic rocks. The formations show marked lateral variation in thickness, lithology, and sediment characteristics, which are related to the geotectonic settings of the basins at active plate margins.
Remarkable accumulation of overburden and high paleogeothermal conditions, which are marked in northern Kyushu, Japan, and Thailand, influenced diagenesis. Organic and inorganic maturation studies in northern Kyushu reveal a progress of diagenesis from the inland of Kyushu toward the sea region essentially controlled by additional heat supply from the sea region during and after sedimentation. The sediments on the land surface are chiefly overmatured, and/or contain minor amounts of organic carbon. High paleogeothermal influence on Tertiary maturation is clear also in northern Thailand. The high paleotemperature conditions in these areas may be related to tectonic interaction between the oceanic and continental plates.
Tertiary sedimentary rocks are thought to extend under the sea region west and southwest off Kyushu, and are expected to be of suitable maturity for hydrocarbon generation. They should be successfully explored in the future.
AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994