| Title | Integrated Interpretation of Heliborne AGG and AEM Data for Geothermal Exploration in the Musadake-Teshikaga Area of Japan |
|---|---|
| Authors | Jurriaan FEIJTH, Jackie HOPE, Hiromasa ISHIKAWA, Atsushi SHIROTA, Takuji MOURI, Gen NAKAMOTO |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Musadake-Teshikaga, Japan, Helitem, HeliFalcon, agg, aem, magnetics, geophysics, integrated interpretation |
| Abstract | An integrated geological interpretation was completed on heliborne multi-physics data for Japan Oil, Gas and Metals National Corporation (JOGMEC) in the Musadake-Teshikaga area, Hokkaido, Japan. HeliFalcon® airborne gravity gradiometer (AGG) and Helitem® airborne electromagnetic (AEM) and magnetic data were acquired and interpreted to aid in the identification of prospective areas for geothermal energy generation. The interpretation workflow included: 1) Investigation of the regional geologic setting, using publically available data 2) Interpretation of the acquired AGG, AEM and magnetic datasets individually 3) Integration of the AGG, AEM and magnetic interpretations 4) Identification and prioritisation of the prospective geothermal zones Available geological and published data was also integrated into the geological interpretation. Tectonic and volcanic lineaments were mapped using the AGG, magnetic and AEM data. The AEM data was also used to identify low resistivity zones that potentially correspond with hydrothermal alteration zones. Northeast lineaments parallel to the Akan-Shiretoko volcanic chain form the most continuous structures in the Musadaka area. These are interpreted to define the Kuril Arc before it was segmented into rotated fault blocks as a result of the collision of this arc with eastern Hokkaido. In the western Teshikaga area, located closer to the Mid Kuril Arc fault, lineaments trending west to west-southwest are more prevalent and offset the older northeast trend. Timing of volcanism in the survey area appears directly related to fault activity. In the Musadake area, volcanism is generally of Miocene to Pleistocene age; in the west, younger Pleistocene to Recent volcanics dominate. The rhombic shape of volcanic structures in the west, defined in the lineament interpretation from all datasets, suggests a hybrid tectono-volcanic origin in a pull-apart setting along the Mid-Kuril Arc fault system. Low resistivity zones were mapped from the AEM data and appear to correlate with areas that have relatively low magnetic amplitudes. This suggests possible magnetite destruction and demagnetization related to thermal or hydrothermal activity. Low resistivity zones are more pronounced and common in the eastern Musadake area. The low resistivity zones and low magnetic amplitude anomalies appear structurally well-defined in the geophysical datasets. These prospective zones are subject to more focused geothermal exploration. |