首页 > 地调专题 > 局其他活动 > 第八届国际天然气水合物大会 > T2自然系统：区域研究-水合物饱和度
OS4A-3:METHANE SOURCE AND FLUX IN GAS HYDRATE POTENTIAL AREA OFFSHORE SOUTHWESTERN TAIWAN
发布时间:2014-07-28
Tsanyao Frank YANG1, Nai-Chen CHEN1, Chin-Yi HU1, Pei-Chuan CHUANG1, Hsuan-Wen CHEN1, Saulwood LIN2, San-Hsiung CHUNG3, Yunshuen WANG3, Po-Chun CHEN3
1. Department of Geosciences, National Taiwan University, Taiwan; 2. Institute of Oceanography, National Taiwan University, Taiwan; 3. Central Geological Survey, MOEA, Taiwan
The widely distributed BSRs imply the existence of potential gas hydrates in offshore southwestern Taiwan. To better constrain the gas sources in this area, in total 22 cores have been collected from different tectonic environments in offshore SW Taiwan during the r/v Marion Dufresne 178 cruise, including 17 giant piston cores, 4 CASQ box cores, and 1 gravity core. The results show that the major gas is methane with very few ethane and carbon dioxide. It indicates they are mostly biogenic source in origin. However, some gas samples from active margin do also exhibit heavier carbon isotopic compositions, which range from -40 to -60 permil and are similar with the gas composition of inland mud volcanoes of SW Taiwan. It implies that there is also thermogenic gas source in this region. Total changes of the dissolved inorganic carbon (DIC) fluxes can be used to estimate the methane flux quantitatively, and we confirm that the sulfate depletion is mainly controlled by the anaerobic oxidation of methane (AOM) reaction and/or the sedimentary organic matter in this area. Although BSRs are widely distributed both in the active margin and in the passive margin, the methane fluxes in active margin are higher than in passive margin of the coring sites. Therefore, we consider that different tectonic settings in offshore SW Taiwan might strongly control the stability of gas hydrates, and then affect the methane concentrations and fluxes of the cored sediments.
1. Department of Geosciences, National Taiwan University, Taiwan; 2. Institute of Oceanography, National Taiwan University, Taiwan; 3. Central Geological Survey, MOEA, Taiwan
The widely distributed BSRs imply the existence of potential gas hydrates in offshore southwestern Taiwan. To better constrain the gas sources in this area, in total 22 cores have been collected from different tectonic environments in offshore SW Taiwan during the r/v Marion Dufresne 178 cruise, including 17 giant piston cores, 4 CASQ box cores, and 1 gravity core. The results show that the major gas is methane with very few ethane and carbon dioxide. It indicates they are mostly biogenic source in origin. However, some gas samples from active margin do also exhibit heavier carbon isotopic compositions, which range from -40 to -60 permil and are similar with the gas composition of inland mud volcanoes of SW Taiwan. It implies that there is also thermogenic gas source in this region. Total changes of the dissolved inorganic carbon (DIC) fluxes can be used to estimate the methane flux quantitatively, and we confirm that the sulfate depletion is mainly controlled by the anaerobic oxidation of methane (AOM) reaction and/or the sedimentary organic matter in this area. Although BSRs are widely distributed both in the active margin and in the passive margin, the methane fluxes in active margin are higher than in passive margin of the coring sites. Therefore, we consider that different tectonic settings in offshore SW Taiwan might strongly control the stability of gas hydrates, and then affect the methane concentrations and fluxes of the cored sediments.
京公网安备 11010202007433号