莺歌海盆地中央坳陷带海底天然气渗漏系统初探

地球物理资料表明，莺歌海盆地区麻坑众多，浅层气发育，在高分辨率地震剖面上可以识别出到达海底的地震模糊带，在3.5 kHz的浅层剖面上可见穿透到海底的气体聚集带，在声呐图像可以识别出麻坑.莺歌海盆地不仅在其边缘隆起带沉积层较薄的地区存在海底天然气渗漏现象，而且在中央坳陷带沉积层巨厚的地区也存在海底天然气渗漏，海底天然气渗漏在莺歌海盆地是广泛分布的.莺歌海盆地广泛分布的海底天然气渗漏是全球海底天然气渗漏系统的重要组成部分，海底天然气渗漏系统排出的大量甲烷气体的一部分可能穿越水层到达海面.

A preliminary study of seafloor gas seepage in central sag zone of Yinggehai Basin

Gas chimneys are shown on high-resolution seismic profiles in Yinggehai Basin.Some are penetrated to seafloor.Shallow gas accumulation reaching seafloor is also identified on 3.5 kHz sub-buttom profile.Pockmarks are found on side-scan sonar image.Geophysical data show that pockmarks and shallow gas develop in the Basin.Seafloor gas seepages occur not only in margin uplift area with thin sediments but also in central sag area with thick sediments in Yinggehai Basin.They are widely distributed in the basin.Seafloor gas seepages in Yinggehai Basin are important parts of worldwide seafloor gas seepage system.Parts of methane gases released by seafloor seepage system may pass through water column and reach to the sea surface.