东沙群岛西南陆坡区泥火山群成因研究

反射地震与浅地层剖面资料显示东沙群岛西南深水陆坡存在一批高达百米的丘状地质体，其沉积层发生强烈挤压褶皱，伴有气体喷溢，推测是尚在活动的泥火山群，并可能是一个新的水合物富集带。为证实此推测并探究该泥火山群的成因，拟以已有资料为基础，搭载航次补充地球物理调查和海底浅层沉积取样；通过反射地震和浅地层剖面数据的多层次成像，获得深穿透和高分辨率反射图象，揭示泥火山的深部构造和浅表层结构；通过改进物理参数反演方法，利用Chirp浅地层剖面记录对海底沉积物物理性质进行预测；对采集的沉积样品进行声学和化学测定，分析浅表层物质组成和气体成分，确定水合物存在标志；分析东沙泥火山分布与区域断裂活动的关系，揭示泥火山形成的地质动力。项目研究可望填补南海北部被动陆缘区泥火山研究空白，并为水合物勘探做出贡献。

Reflection seismic and subbottom profiling data show that numerous mound-like structures stand up to 100 m high above the seafloor over the continetal slope to the SW Dongsha Island, which feature of highly folded sedimetary strata and gas venting, and were speculated as active abyssal mud volcanoes that may prospect rich hydrates. To confirm the speculation and get insights to the geological origin of the mud volcanoes, it is planned to collect new geophysical data and dredge the seabed during open cruises to get deep penetration images of their deep structure and high-resolution images of their shallow levels with multiple channel seismic and Chirp sub-bottom profiling data, to improve the method of parameter inversion from sonic reflectivity in order to predict the physical property and lateral variation of seabed hardness and gas venting due to mud volcanism, to analyze the components of the sediments and gases by physical measurements and chemical analysis with the samples dredged from the seabed, and to identify proxies of hydrates, to reveal the geological dynamics to produce the mud volcanoes by analyzing their relevance of regional tectonic activity. This study may fill a research gap of mud volcano over the passive northern margin of the South China Sea and thus contribut to the prospect of gas hydrates.