| 摘要: | 海洋蘊藏豐富的多金屬熱液硫化礦床，因海底熱液活動使得海底硫化物資源主要集中在海底火山、中洋脊和弧後盆地張裂帶上。沉積物及海水產生熱液換質和礦化作用，形成富含金、銀、銅、鉛、鋅、砷、銻等金屬元素，而成為一種潛在的海底礦產資源。在地調所第一期（105-108）的「臺灣東北海域礦產資源潛能調查計畫」中，針對沖繩海槽的最南端弧後張裂盆地進行高解析聲納的探測，本團隊使用多音束水深系統、高解析聲納系統、磁力儀與海底地震儀等探測儀器與方法，進行多金屬熱液硫化礦床之相關調查研究。根據本案調查成果，地調所共提出有9處極具潛能的多金屬熱液硫化礦床，其中的6處場址，則更進一步得到地物、地化、海床觀測等三個團隊的資料佐證。也可以證明本團隊對於本案具有實質的重要貢獻。此第二期（109-112）的「臺灣東北部礦產地質調查」是以台灣東北部海域的火山島及海底火山區域為調查重點，相信本團隊仍能順利完成作業目標，並提出重要發現與貢獻。 今（109）年度計畫之主要調查研究區域就位在基隆外海的基隆嶼及基隆海底火山區域。藉由研究區域的高解析聲納資料和多音束水深資料，提供詳細的海底地形圖資、地貌特徵與淺部地層構造。磁力資料的收集及分析，則可以建立磁化強度分布概況、辨識熱液噴口的位置。綜合這些地球物理研究相關資料，進而瞭解台灣東北部火山島嶼與海底火山，其周圍的火成岩體與熱液硫化礦床的可能分布、海底淺部地層沉積物之沉積特徵及特殊構造現象，並研判熱液硫化礦床在地層中可能的通道或路徑。再進一步配合其它地球物理、地球化學及海床觀測等探測結果，評估多金屬熱液硫化礦床的分布範圍及資源潛能。此外，本計畫也將同時整理台灣東北部海域火成及熱液作用活躍區的多音束精密水深資料，並繪製全區水深圖，作為相關研究所需之精密海底地形圖，幫助建立東北海域基礎地質資料。 ;Deep-sea hydrothermal vents generally focus in submarine volcano, mid-ocean ridges or back-arc basins. Because of hydrothermal circulations, sulfide-rich fluids contain metal sulfides. Due to the rich concentrations of metals, such as gold, silver, copper, lead, zinc, arsenic and antimony, submarine hydrothermal activity areas become potential undersea mineral resources. In the first phase (2016-2019) of the "Investigation of Mineral Resource Potential in the Offshore Northeastern Taiwan", high-resolution sonar surveys were performed in the southernmost of the Okinawa Trough, a back-arc rifting basin. Our team used multi-beam echo sounder, high-resolution sonar system, magnetometer and ocean-bottom seismometer to detect and study related polymetallic hydrothermal sulfide deposits. According to the investigation results of that project, the Central Geological Survey (CGS) proposed 9 potential polymetallic hydrothermal sulfide deposits. Six of those sites were confirmed by the data of geophysical, geochemical and seabed observations. The results confirm that our team has significantly contributed to the seabed investigation of marine mineral resources. In this second phase (2020-2023), the project of the "Geological investigation of mineral deposits in northeastern Taiwan" focuses on the volcanic islands and submarine volcanic areas in the offshore of northeast Taiwan. We believe that our team can still successfully fullfil the goals of the project and provide important discoveries and contributions. The target area of this (2020) year is located between the Keelung Island and Keelung Submarine Volcanic area off Keelung in the offshore of northeastern Taiwan. Based on the high-resolution sonar and bathymetric data, the geologic features related to diking, faulting, and lava flow emplacement would be identified. The distribution of hydrothermal systems could provide the physical pathway for fluids from the subsurface to the seafloor. The magnetic data can indicate hydrothermal vents and can find the areas where the corrosive vent fluids have demagnetized the crust through chemical alteration. The integration of all these geophysical and chemical results can provide more information on the sedimentary features in the submarine strata, the distribution of the volcanic rock and hydrothermal deposits, and the possible fluid pathways. We estimate the potential of the mineral resource by integrating our results with chemical observations. Finally, the detailed multi-beam bathymetry data acquired during this project will be used to compile a regional bathymetry map, which can help construct submarine geological maps off northeastern Taiwan. |
