Structural features of potential gas hydrate area in the Pointer Ridge off southwest Taiwan

Presenter：Hsueh-Fen Wang               Adviser： Shu-Kun Hsu

Abstract
The offshore area of the southwest Taiwan is located in the oblique convergence zone between the northern continental margin of South China Sea and the Manila accretionary wedge. To the west of the deformation front offshore southwestern Taiwan, the Pointer Ridge is located in the passive South China Sea continental margin. The continental margin is compose of extensional horst-and-graben structures. There are numerous submarine channels and linear ridge, formed due to the submarine erosion  across the continental slope region. According to geophysical research off SW Taiwan, abundant gas hydrate may exist. In this study, our purpose is to understand the relationship between the near-seafloor structures of the Pointer Ridge and the gas hydrate formation off SW Taiwan.
The data we used include multi-beam echo sounder (MBES), side-scan sonar (SSS), sub-bottom profiler (SBP) and the multi-channel reflection seismic (MCS) data. Our results show the pockmark and gas seepage structures mainly appear in the place where the gradient of the BSR thickness is maxium. Those sites contain authigenic carbonate sighnature shown in the sub-bottom profiler. We also observe several folds and faults structures in this extensional background; however, these compressional features need further studies.

References
Milkov, A.V., Sassen, R., 2001. Estimate of gas hydrate resource, northwestern Gulf of Mexico. Mar. Geol. 179, 71–83.
Rodriguez, N.M., Paull, C.K., and Borowski, W.S., Zonation of authigenic carbonates within gas hydrate-bearing sedimentary sections on the Blake Ridge: offshore southeastern North America, (Paull, C.K., Matsumoto, R., Wallace, P.J. and Dillon, W.P. (eds)), Proceedings of the Ocean Drilling Program Scientific Results 164, 301–312, 2000.
Hovland, M., On the self-sealing nature of marine seeps, Continental Shelf Research 22, 2387–2394, 2002.
Liu C.-C., P. Schnurle, Y. Wang, S.-H. Chung, S.-C. Chen, T.-H. Hsiuan: Distribution and Characters of Gas Hydrate Offshore of Southwestern Taiwan. Terr. Atmos. Ocean. Sci., 17, 615-644, 2006.
陳松春，臺灣西南海域上部高屏斜坡泥貫入體及泥火山之分布及相關海床特徵，中央大學地球物理研究所博士論文，2013。