【摘要】 南海东北部海域水深、沉积厚度大、沉积速率高和有机质含量丰富,为马尼拉增生楔中天然气水合物成藏提供了必要的气源,且相应适宜的温压条件以及构造背景也有利于天然气水合物的形成与赋存,其中马尼拉俯冲带俯冲前缘以及增生楔中的断裂系统成为天然气水合物成藏的非常重要的运移通道。通过对地震剖面中断裂系统和三维地貌图的精细解释,分析了马尼拉海沟俯冲带存在的海沟前缘正断层、海沟轴部的盲断层以及增生楔中的盲冲断层或逆冲断层,直到最后发育成隔断叠瓦状岩片的逆冲断层组,这些断裂系统反映出增生楔上天然气水合物的含气流体的形成、运移及聚集过程,成为天然气水合物成藏的运移通道。更多还原

【Abstract】 Great depth of water and thickness of sediment,high rate of deposition and rich content of organic matter in northeastern South China Sea provide the formation of gas hydrate with the necessary gas supply.In addition,the appropriate condition of temperature and pressure and tectonic setting are favorable to the occurrence of gas hydrate.Specially,the fault system in the deformation front and accretionary wedge of Manila subduction zone is proved to be the pathway of gas-bearing fluid migration of gas hydrate.Based on the marine geology of northeastern South China Sea or offshore of southwestern Taiwan,multiple-channel seismic profiles and high resolution sub-bottom 3D-topographic images interpreted and analyzed,it is found that there are many normal faults in the deformation front,blind faults in the trench axis and(blind) thrusts in the accretionary wedge,which developed into thrust group that divided into the imbricate thrust sheets.The all faults and thrusts make up a fault system,constituting of normal faults,blind faults and(blind) thrusts.The fault system mentioned above not only reflects the process of South China Sea plate diving underneath of Luzon island arc,but also is regarded as the channel of fluid migration,indicating the process of formation,migration and concentration for fluid of gas hydrate in accretionary wedge.更多还原