著者

浜田 好弘 田中 和広 宮田 雄一郎

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.118, no.3, pp.408-423, 2009-06-25 (Released:2010-03-26)

参考文献数

38

被引用文献数

9 8

---

The geology and geochemistry of mud volcanoes in Taiwan was investigated to elucidate the relationship between their distribution and geological structure and the mechanism of ascending fluid migration from deep underground regions caused by abnormal pore water pressure. A detailed geological survey was carried out to describe the geological structure and the stratigraphy of mud volcanoes in the Pliocene Gutingkeng Formation in the Hsiaokunshui area. Groups of several to tens of mud volcanoes are distributed along the anticline axis within an area of 400 m in diameter. Mud volcanoes are classified into three types on the basis of differences in their morphological features (pudding type, crater type and pool type) corresponding to three types of erupted groundwater having different viscosities. As a result of geochemical studies on groundwater that erupted from mud volcanoes, it is shown that the geochemistry of groundwater that erupted from mud volcanoes distributed along the anticline, such as the Hsiaokunshui mud volcanoes, is characterized by lower δ18O ratios and high concentrations of soluble ions compared to those distributed along the Chishan Fault. Also, it is concluded that pressurized groundwater diluted by water produced during the dehydration of clay minerals ascended through the Chishan Fault and along the Hsiaokunshui anticline. On the other hand, on the basis of high δ18O ratios, it is suggested that the groundwater of mud volcanoes along the Chishan Fault was quickly expelled from underground regions deeper than those along the Hsiaokunshui anticline. Also, the groundwater of mud volcanoes along the Hsiaokunshui anticline ascended through a variety of paths from the mud chamber to the ground surface, and consequently various types of mud volcanoes were formed on the ground surface.