| 摘要: | 海床具有蘊藏豐富的多金屬熱液硫化礦床的潛能，因海底熱液活動使得海底硫化物資源富集中在海底火山、中洋脊和弧後盆地張裂帶上周圍。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，而成為潛在的海底礦產資源。在地調所第二期（109-112年）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，本團隊使用海底地形、底拖聲納資料與磁力資料共三項作業，針對地質構造、火成岩體、噴氣現象、其他熱液換質現象等，進行相關調查研究。 本（110）年度計畫，主要目標著重在台灣?部海域(含花瓶嶼)區域的既有資料蒐集及分析工作。 109年度我們已完成高解析海底地形成果方面，除了完成作業區域1 m解析度的海底地形圖資外，也完成作業區域周圍的海底地形圖資整編。基隆海底火山及其東側地形凹陷區，以及野柳線型為較明顯的地貌特徵。磁力結果顯示有一東北-西南向的可能火山磁力高區，從北邊彭佳嶼、花瓶嶼到台灣本島北部高磁力異常區之間。根據底拖聲納調查結果顯示，109年度調查區域內具有相當明顯的火成作用與熱液活動相關特徵，包含海底火山、強反射層、噴氣柱、流體通道等近海床的構造特徵。調查區域的淺部地層中，流體通道分布廣泛，水層中噴氣柱分佈密集，顯示熱液活動活躍。根據近海床高解析資料的分析結果，基隆海底火山周圍及其東側地形凹陷區可能具有熱液硫化礦物的潛能。相較基隆海底火山區域而言，在地形凹陷區中間偏東的區域，流體通道、強反射層與噴氣柱呈現出約略東北西南走向的連續帶狀分布，並往南延伸至基隆嶼北側。並且該區有近海床流體通道與聲波強反射層（疑似熱液作用沿地層滲入形成的礦脈），有些甚至已經出露海床。因此，本團隊建議這個區域未來可以加強探測，提供更詳細熱液硫化礦物的潛能分析。 為了瞭解整個瞭解臺灣東北部海域火成活動分布範圍及熱液換質與礦化作用的特性，本（110）年度計畫延續109 年度的區塊，繼續規劃往其北側探索，主要目標區著重在往北的海域含花瓶嶼周圍的區域。藉由彙整和分析既有研究區域的高解析底拖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。綜合這些地球物理研究相關資料，可以瞭解台灣東北部的火成岩體、噴氣現象、其他熱液換質現象與海床淺部地層沉積物之地質構造特徵，並推論熱液硫化礦床在地層中可能的通道。最後配合其它地球物理、地球化學及海床觀測等探測結果，評估熱液活動分布範圍。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。 ;Hydrothermal vents are generally distributed near submarine volcanoes, mid-ocean ridges or axial depressions of 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 reveal potential undersea mineral resources. The second phase (2020-2023) of the project "Geological investigation of mineral deposits in northeastern Taiwan" focuses on the volcanic islands and submarine volcanic areas offshore northern Taiwan. Our team used multi-beam echo sounder, high-resolution sonar system, magnetometer data to study the potential areas of related investigations and studies on geological structures, igneous rock, gas plume, other hydrothermal mass transfer phenomena, etc. In 2021, we will focus on the collection and analysis of existing data in the area around Huaping Islet, off northern Taiwan. In 2020, we have compiled 1 m grid bathymetric map, we have also compiled the bathymetric data around the investigation area. The main bathymetric features include the Keelung Submarine Volcano, a bathymetric depression area in the east and the linear structure along the east side of the Yehliu Cape. Our magnetic data show that there was a roughly NE-SW trending high magnetization zone from Pengchiayu Islet to Mianhua Islet and northern Taiwan. According to our deep-tow sonar survey results, the volcanic and hydrothermal activities are still remarkable, including active gas flares, fluid channels and other high acoustic reflectance features in the shallow seabed. Fluid channels and gas flares (plumes) in the seawater are widely distributed in our investigation area, indicating hydrothermal activity is active. Particularly, some near-surface fluid channels and strong reflectance layers are exposed to the seafloor. We suggest that those areas should be investigated further in the future, so that more detailed data can be used to evaluate the potential of hydrothermal sulfide minerals. In order to better understand the hydrothermal system in northeastern Taiwan, we will extend our research area further north in 2021.The target area of this (2021) year is in the area around Huaping Islet off northern Taiwan. Based on the high-resolution sonar and bathymetric data, the geologic features related to hydrothermal activity will be analyzed. The integration of all the geophysical and chemical results can provide more comprehensive information on the sedimentary features of the strata and better understand the distribution of the hydrothermal deposits and the possible fluid pathways. Like the geochemical results, our results will help estimate distribution range of hydrothermal activity. Finally, the detailed multi-beam bathymetry data collected during this project will be used to compile a regional bathymetry map, that can help construct submarine geological maps off northeastern Taiwan. |
