| Abstract |
A geothermal resources map of the Kyushu Region, southwest Japan, was compiled at 1:500,000 scale for understanding an outline of geothermal resources areas and relation between the distribution of geothermal resources and regional geologic/tectonic settings. Hot springs, fumaroles, geothermal wells and geothermal resources areas are plotted on a simplified geologic map with Bouguer anomaly contour lines. The map is to be published in 2000. Geologic units were classified into 10 Neogene to Quaternary units and two units of pre-Neogene basement rocks. Active faults, active volcanoes and calderas younger than ca. 2 Ma and Bouguer anomalies were also indicated on the map. Hot springs were classified by water temperature, pH, total dissolved matter and major anion composition. Fumaroles were classified by maximum temperature, and geothermal exploration wells were classified by maximum well temperature and well condition. Geothermal resources areas were categorized into following three types. 1) Geothermal resources area related to Quaternary volcanoes, 2) Deep-seated hot water resources area, and 3) Geothermal resources area not related to Quaternary volcanoes, and the last was subdivided into 3A) type A and 3B) type B. Geothermal resources areas except type 2) areas are classified into 3 ranks (rank A, B and C) based on their geothermal potential. The map was digitally edited by GIS software. It allows us to maintain data easily and to distribute the map and data in digital publishing form such as CD-ROM. A rough comparison of the numbers of the geothermal resources area between Tohoku and Kyushu revealed the similarity of importance of young volcanism to the high temperature geothermal resources in both areas. The number of geothermal areas not related Quaternary volcanoes in Kyushu is less than that in Tohoku. This difference may be caused by the lack of Miocene volcanism and formation of sedimentary basins since Miocene in Kyushu. |