Study of Relationship between In-Situ Stress and Fluid Conduits in Hongchailin of Ilan Plain, NE Taiwan

Ilan plan in northeastern Taiwan possesses abundant geothermal resources resulted from a higher geothermal gradient due to the influences of compression of mountain building and extension of back-arc rifting. Understanding in-situ stress field can evaluate current extension state for benefiting geothermal exploration and development and providing important information to geothermal engineering. Because development of geothermal fluid conduits is highly depended on in-situ stress, for enhancing geothermal productivity, this study conducted Anelastic Strain Recovery (ASR) and core description to study the relationship between in-situ stress and fluid conduits in Hongchailin area, Ilan Plain. Based on experiments of ASR, this study assessed in-situ 3D stress field including stress direction. Information of fractures and veins with depth obtained from core observation provided insights into the distribution of fluid conduits. Current results display a mixing stress regime of normal faulting and strike-slip faulting with NW-SE compression and SW-NE extension, which is consistent with results of focal mechanisms. Results of core description showed E-W striking gouge, indicating an early N-S compression. The fluid conduits with NW-SE strike are consistent with the predicted conduits inferred from in-situ stress field. Integrating with other information of stress direction and magnitude will provide insights into developing enhanced geothermal systems and utilizing geothermal energy efficiently.