臺灣西南海域高屏斜坡上活躍的泥火山群與可能的天然氣水合物賦存

Active Mud Volcanoes and Potential Gas Hydrate In the Upper Kaoping Slope Offshore SW Taiwan

陳松春(S.C. Chen) ； 許樹坤(S.K. Hsu) ； 王詠絢(Yun-Shuen Wang) ； 蔡慶輝(C.H. Tsai)

《鑛冶：中國鑛冶工程學會會刊》 56卷3期 (2012/09) Pp. 73-88

https://doi.org/10.30069/MM.201209.0007

摘要

為進行天然氣水合物之調查研究，從2009到2010年我們在臺灣西南海域高屏上部斜坡附近實施多音束水深及底拖底質剖面探測。從多音束水深資料，可以辨識出13處海底泥火山，而從高解析底質剖面及EK500聲納資料更可分別勘察出海床下超過100處之逸氣通道及10處海床上噴氣構造。海底泥火山均被發現位於泥貫入體之頂部，其形成原因明顯和泥貫入體之發育相關。2011年我們首次在國內使用無人遙控載具（ROV）進行海底泥火山之攝影觀測，發現3處泥火山有活躍的噴發，泥火山MV1及MV5大約每3至8分鐘噴發一次，而MV12約每3至10秒噴發一次。經分析泥火山上部之海水發現甲烷濃度高達100～550 nL/L，遠高於海水背景值50 nL/L，指示有相當高之甲烷通量進入水體，另外從反射震測資料也可辨識出明顯的海底仿擬反射（BSR）分布，暗示台灣西南海域的地層下部有豐富之天然氣水合物賦存。

關鍵字

海底泥火山 ； 逸氣通道 ； 天然氣水合物 ； 無人遙控載具

並列摘要

In order to understand the gas hydrate potential in the upper Kaoping slope offshore SW Taiwan, we have conducted multibeam echo sounder and deep-towed sub-bottom profiler surveys from 2009 to 2010. Thirteen submarine mud volcanoes are recognized from multibeam bathymetry. The high-resolution sub-bottom profiler and EK500 sonar data respectively show the existence of more than one hundred gas seeps and ten gas plumes in water column distributed in the study area. These mud volcanoes are situated at the summits of mud diapiric structures. It indicates that the mud volcanoes are closely associated with the mud diapiric structures. We have conducted a ROV survey for mud volcanoes in the near shore area off SW Taiwan in 2011. The ROV observations reveal three active mud volcanoes erupting from seafloor. The eruption periods of mud volcanoes MV1 and MV5 are about every 3 to 8 minutes, and MV12 is about every 3 to10 seconds. The water columns above the mud volcanoes have high methane concentrations (100~550 nL/L; the average seawater ＜ 50 nL/L) implying a high methane flux beneath the mud volcanoes. MCS profiles also clearly show a wide distribution of BSR throughout the study area implying a high potential of gas hydrate in the sediments offshore SW Taiwan.

並列關鍵字

submarine mud volcano ； gas seep ； gas hydrate ； ROV