Study of Stress State around the Chinshui Geothermal District of Ilan Area, Taiwan

• Main Authors: Tien-Hsiang Sun, 孫天祥
• Other Authors: En-Chao Yeh
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/42334580630745948613

碩士 === 國立臺灣師範大學 === 地球科學系 === 102 === In order to relieve the dependence on fossil fuels and reduce the production of carbonate-dioxide, the development of neo-energy is not only one of the best ways to work out but also the latest trends in the world. Among all the neo-energy sources, geothermal power plant is a well-developed technique. Chinshui geothermal district, Ilan, Taiwan has been known as one of famous geothermal districts for decades. Some preliminary research shows that there is a huge geothermal reservoir right below Chinshui, Ilan. It would be a great help to the energy policy if the efficient geothermal power plant could be set up here. Understanding fluid conduit fractures is the key to develop geothermal power plants and further Enhanced Geothermal System (EGS). Assessing stress-state (both paleo &; in-situ stress) helps out evaluating history evolution of stress states. Base on in-situ stress state in addition to fracture orientation, the passage or barrier of various fractures can be determined. Chinshui, Ilan locates in the western slate belt of Backbone Range, NE Taiwan. The variation of stress state here is quite complicated since the complex tectonic history of NE Taiwan resulted from collision to back-arc extension. In this work, multi methods were applied to find out the stress states around Chinshui, Ilan. In order to evaluate paleo-stress states, analysis of heterogeneous fault-slipdata such as slickenside and quartz and calcite steps collected from outcrop along 10 km-long Chinshui area. Results show that at least three stages of stress state can be determined. On the other side, to know in-situ stress state, Anelastic Strain Recovery (ASR) method, a core-based method, was applied on the core retrieved form a latest drilling bore-hole of IC-21. Results show that NE-compression and NW-extension of strike-slip faulting stress regime with a low stress ratio. This result consisted with the youngest stage of stress state inferred from fault-slip analysis, impling that this strike-slip stress regime is the in-situ stress throughout the Chinshui geothermal district, Ilan.