關鍵詞：天然氣水合物、側掃聲納、底質剖面儀、海底地電阻探測、多音束水深 摘要 本計畫是為執行中央地質調查所推動之4年期（2012~2015）「天然氣水合物資源能調查：高解析聲納調查」工作，將以高解析聲納探測方式，進行天然氣水合物之相關調查研究，以瞭解探勘好景區之海底地貌特徵，判釋冷泉或特殊構造區（如泥火山、泥貫入體、麻坑等）的分布，瞭解海底淺部地層沉積物之沉積特徵及特殊構造現象，並研判氣體逸出之可能通道或路徑，同時將提供海床淺層天然氣水合物儲集系統分析之參考依據；將逐步收集西南海域全區精密水深資料，繪製全區海底地形圖，作為底拖儀器探測與相關研究所需之精密水深參考資料。為達成本計畫之目標，4年期計畫將進行高解析底拖聲納探測（包含底質剖面及側掃聲納）、多音束水深資料收集及進行海底地電阻試測等工作。 在去年（101年度）底拖聲納作業區位於好景海脊與永安海脊南端，根據收集資料分析的結果，發現在永安海脊南端有密集的麻坑分布，並有許多淺部正斷層構造與崩塌堆積層。自生碳酸鹽礁除了分布在地層中，在好景海脊南端因背斜構造所形成地形高區的海床表面，也發現大面積自生碳酸鹽礁的覆蓋。另外，我們也發現海床線形構造其實是與崩塌堆積層密切相關，有些區域會同時出現麻坑構造，利用與MD178-3277岩心及電阻率異常區比對的結果，推測有這種近海床構造的地層，含有天然氣水合物儲集的機會相當高。 綜合歷年在好景海脊與永安海脊各種地質、地物與地化資料的分析成果，都顯示在好景海脊與永安海脊之間的淺部地層中，具有天然氣水合物儲集的可能。本計畫（102年度）將以台灣西南海域對天然氣水合物之分布與特性之調查結果為基礎，繼續進行高解析聲納探測及多音束水深資料收集，以提供瞭解臺灣西南海域天然氣水合物的分布與資源潛能。本（102）年度計畫進行之調查研究工作包括： 1、在永安海脊及好景海脊區域，進行底拖聲納探測（包含底質剖面及側掃聲納）。 2、在澎湖峽谷上游的變形前緣兩側區域，進行多音束水深資料收集。 3、改善既有海底地電阻資料的處理與分析，並與相關地物、地化與底拖資料作緊密結合的整體解釋。 ; KEYWORDS: Gas-Hydrate; Sidescan Sonar; Sub-bottom Profiler; Multibeam; Resistivity Abstract This proposal belongs to a 4-years project "Investigation of Gas Hydrate Resource Potential: High-resolution Sonar Surveys" of the Central Geological Survey from 2012 to 2015. The high-resolution deep-tow sonar will be used for the gas hydrate study. The purpose is to understand the characteristic features of the seabed and to identify the distribution of cold seeps, mud volcanoes, mud diapirs, pockmarks. We will study the characteristics of the sedimentary strata and analyze the possible gas migration conduits or paths. Meanwhile, we will study the shallow features of seabed for gas hydrate reservoir system. We will gradually compile a high-resolution bathymetry off SW Taiwan. We will also explore the formation of shallow resistivity characteristics, to understand the near seabed distribution of gas hydrate. To do this four-years project, the high-resolution sonar (including sub-bottom profiler and sidescan sonar), multi-beam echo sounder surveys and marine resistivity measurements will be conducted. For the first year (2012), the deep-towed sonar survey area is situated in the southern end of the Good-Weather Ridge and the Yuan-An Ridge. The results indicate a prominent pockmark area distributed in the southern end of the Yuan-An Ridge and accompanied by many shallow normal faults and landslide mass transport deposit layers. Additionally, authigenic carbonates are distributed on top of an anticline structure in the south of the Good-Weather Ridge. We also found some linear structures and some pockmarks together with landslide deposit layers. Taking into account MD178-3277 core data and resistivity anomaly area, we suggest that the potential storage of the gas hydrate is high in the study area. According to many geological, geophysical and geochemical data analysis results, a possible formation of shallow gas hydrate reservoir exists between the Good-Weather Ridge and the Yuan-An Ridge. In addition, we will keep compiling a high-resolution topography map for an important reference of the gas hydrate investigation. This project will be based on the results of the existing data from the gas hydrate studies off SW Taiwan. We will keep on conducting high-resolution sonar and multi-beam echo sounder surveys in order to provide a better understanding for the potential distribution of gas hydrate resources off SW Taiwan. The targets of this year work consist of: 1. To conduct deep-towed sub-bottom profiler and sidescan sonar surveys in around the Yun-An Ridge and Good Weather Ridge. 2. To conduct multi-beam echo sounder surveys in the upstream area of the Penghu Canyon. 3. To improve marine geoelectric data processing and analysis in order to be interpreted together with other geophysical and geochemical data. ; 研究期間 10201 ~ 10212
