2011-01-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/671042摘要：台灣西南海域同時擁有活動與被動大陸邊緣兩種不同的大地構造系統，不同區域之大地構造的差異可能對於地層中甲烷來源與移棲途徑及其對淺層與深部沉積物地質地化特徵有極大的影響，然而對於整個海脊構造及不同海脊構造之間甲烷移棲及沉積物地質地化特徵的區域性差異尚未能有全盤的瞭解。因此「地球化學調查研究」計畫擬分年針對不同之海脊構造進行全面性的岩心採樣及TowCam調查研究，深入探討從台南、永安、好景及枋寮海脊與變形前緣深水區，以及被動大陸邊緣海域，不同海脊構造環境之甲烷移棲現象及其對於淺層沉積物地質地化特徵的影響，以瞭解調查區域內何處呈現甲烷氣從深部強烈往上移棲的現象，進而判定該強烈甲烷移棲的區域地層中可能賦存豐富的天然氣水合物，並進一步探討何種大地構造環境為天然氣水合物最佳的賦存區域。 100年度計畫各項研究工作分由六個子計畫進行： 子計畫(I)：台灣西南海域海水與沉積物之氣體化學組成—楊燦堯教授 子計畫(II)：台灣西南海域地質微生物(細菌與太古生物)多樣性調查與天然氣水合物形成與分解機制探討—賴美津教授 子計畫(III)：台灣西南海域自生性碳酸鹽及硫物種之變化與天然氣水合物賦存之關係 —林曉武教授 子計畫(IV)：台灣西南海域天然氣水合物探勘熱區之黏土與自生礦物研究—江威德教授 子計畫(V)：台灣西南海域沉積物之古地磁定年及磁學性質研究—洪崇勝教授 子計畫(VI)：台灣西南海域沉積物基本性質與天然氣水合物賦存之關係—陳汝勤教授 本計畫擬探討天然氣水合物，其甲烷氣於沉積物內之擴散與噴發及受微生物產生之生地化變化，與註記於自生碳酸鹽與硫化礦物等之特徵，並探討其沉積年代與噴發擴散時間，來瞭解天然氣水合物在台灣西南海域活動大陸邊緣增積岩體與被動大陸邊緣二環境之形成與移棲，並藉著沉積物之基本性質來評估天然氣水合物之賦存量。 100年度計畫主要工作擬包括：(1)MD超長岩心之地質地化分析、(2)增積岩體下部陸坡變形前緣區之OR1活塞岩心採樣及海床地貌TowCam拍攝調查、(3)天然氣水合物第二期四年計畫（97-100年度）之研究成果總報告。 本計畫將繼續進行6支99年度計畫未分析之MD超長岩心之地質地化分析，期能更深入瞭解與探討(i)不同大地構造及地層結構區域之深部沉積物與孔隙水地質地化特徵的空間與時序性變化，及其與甲烷移棲和天然氣水合物賦存之關係；(ii)台灣西南海域深部與淺層沉積物地質地化特徵之異同，以及甲烷來源與甲烷移棲模式的差異；(iii)沉積物生地化反應、地質微生物種類及自生性礦物組成隨岩心深度的變化及其與甲烷移棲及孔隙水化學組成之相互關係；(iv)利用MD背景站位岩心建構具有碳十四定年、可靠且連續之磁場世紀變化曲線，作為地質年代的依據。(v)台灣西南海域過去沉積歷史之地質地化特徵與沉積環境的變化；(vi)活動與被動大陸邊緣深部沉積物之甲烷移棲地化模式及天然氣水合物最佳賦存地質條件的異同；(vii)檢驗地球物理徵兆與深部沉積物地質地化特徵是否對於甲烷移棲及天然氣水合物賦存擁有一致的表徵。 本計畫亦預計將申請海研一號兩個5天航次，以期能完成執行下部陸坡變形前緣區之6~18米活塞岩心採樣及海床地貌TowCam拍攝調查，以期(i)瞭解沉積物與孔隙水地質地化特性之空間與垂直分佈變化，及其與甲烷滲漏、移棲和天然氣水合物賦存之關係；(ii)瞭解不同大地構造與地層結構之差異對於沉積物地質地化特性的影響及其與甲烷移棲之關係；(iii)瞭解海床地貌特徵分佈變化及其與甲烷移棲之關係；(iv)瞭解地質微生物種類之區域性差異及其與甲烷移棲之關係；(v)提供預定鑽探井位KP-1-1、KP-1-1、KP-2周圍沉積物之地質地化資料。 本計畫亦將撰寫天然氣水合物第二期四年計畫之研究成果總報告，整合97-100年度各項地質地化分析資料，並與地物及底拖團隊共同評估台灣西南海域天然氣水合物最佳賦存區域及甲烷移棲模式。 <br> Abstract: The existence of both passive and active margin adjacent to each other offshore SW Taiwan is very unique in the marine environment, especially in evaluating formation of gas hydrate under different tectonic settings. South China Sea adjacent to Taiwan provides such a rare opportunity in studying and comparing gas hydrate formation, migration and sea floor phenomena at both active and passive margin environments. Extensive samplings during 2004-2007 in the first phase of Taiwan gas hydrate research program facilitate our basic understandings toward gas hydrate formation and subsequent bio-geochemical processes. However, little is known about how and when gas migration occurs and nature of subsequent microbial activities and other geochemical processes that may alter the gas hydrate formation and migration in both active and passive margin in these areas. Furthermore, findings of hydrothermal like of chemo-communities in the cold seep environment further raise the question of how gas and fluid migration and subsequent chemical processes that may generate such an unusual chemosynthetic community. In order to understand gas hydrate formation in these two environments and to understand the cause and effect of gas hydrate migration, we have re-grouped related PIs in the field. We intend to study gas composition, microbial process and subsequent pore water variations, authigenic minerals formation, paleomagnetic dating, magnetic and sediment properties. Our group includes: (I) T. F. Yang: Studies on the gas compositions in sea water and sediments offshore southwestern Taiwan. (II) M.-C. Lai: Geomicrobial diversity in the gas hydrate potentials regions offshore southwestern Taiwan and its role in gas hydrate formation and degradation (III) S. Lin: Authigenic carbonate formation and sulfur cycle in the active and passive margin offshore southwestern Taiwan. (IV) W.-T. Jiang: Clay- and authigenic-mineral studies of the favorable sites for gas hydrate exploration offshore southwestern Taiwan (V) C.-S. Horng: Paleomagnetic dating and magnetic properties of sediments offshore southwestern Taiwan (VI) J.-C. Chen: The relationship between sediment properties and the occurrence of gas hydrate offshore southwestern Taiwan Major works in 2011 include (1) continue working on samples taken during 2010 MD cruise; (2) OR1 piston core sampling and TowCam survey on the lower slope region near the deformation front; (3) summary report of the entire second phase. For MD cores, sites 3261, 3264, 3276, 3277, 3288 and 3292 will be our target of this year. Major objectives include: (1) to understand spatial and temporal variation of methane migration and subsequent geochemical processes in deep sediments; (2) to compare differences of those geochemical processes in shallow and deep sediments; (3) to understand spatial and vertical variation of microbial diversity; (4) to understand authigenic minerals and their relationship with pore water composition and methane migration; (5) to construct a reliable and continuous geomagnetic secular variation curve by carbon-14 ages on the sedimentary sequences of the background sites; (6) to understand sedimentary history offshore SW Taiwan in order to establish a long-term methane migration model; (7) to construct and compare methane migration model in the active and passive margin sediments. Two 5 days OR1 cruise will be carried out to take piston core samples and TowCam survey. 2011 OR1 survey will be focused on the lower slope region near the deformation front. Major objectives of the 2011 OR1 survey include: (1) to understand lower slope geochemical properties with respect to methane migration; (2) to investigate possibility of gas hydrate occurrence in the lower slope where pressure and temperature are suitable for gas hydrate formation; (3) to understand microbial diversity in the lower slope region; (4) to evaluate and to provide data for drilling sites at the deep water; (5) to summarize all data accumulate in the past 4 years.天然氣水合物活動大陸邊緣被動大陸邊緣冷泉甲烷微生物硫酸鹽還原化學自營性生物自生性碳酸鹽黃鐵礦古地磁定年孔隙率流體移棲gas hydrateactive marginpassive margincold seepmethanemicrobialsulfate reductionchemosynthetic communityauthigenic carbonatepyritepaleomagnetic datingporosityfluid migration