The continental slopes of the Black Sea show abundant manifestations of gas seepage in water depth of <720 m, but underlying controls are still not fully understood. Here, we investigate gas seepage along the Bulgarian and Romanian Black Sea margin using acoustic multibeam water column, bathymetry, backscatter, and sub-bottom profiler data to determine linkages between sub-seafloor structures, seafloor gas seeps, and gas discharge into the water column. More than 10,000 seepage sites over an area of ∼3,000 km² were identified. The maximum water depth of gas seepage is controlled by the onset of the structure I gas hydrate stability zone in ∼720 m depth. However, gas seepage is not randomly distributed elsewhere. We classify three factors controlling on gas seepage locations into depositional, erosional, and tectonic factors. Depositional factors are associated with regionally occurring sediment waves forming focusing effects and mass-transport deposits (MTDs) with limited sediment drape. Elongated seafloor depressions linked to faulting and gas seepage develop at the base between adjacent sediment waves. The elongated depressions become progressively wider and deeper toward shallow water depths and culminate in some locations into clusters of pockmarks. MTDs cover larger regions and level out paleo-topography. Their surface morphology results in fault-like deformation patterns of the sediment drape on top of the MTDs that is locally utilized for gas migration. Erosional factors are seen along channels and canyons as well as slope failures, where gas discharge occurs along head-scarps and ridges. Sediment that was removed by slope failures cover larger regions down-slope. Those regions are devoid of gas seepage either by forming impermeable barriers to gas migration or by removal of the formerly gas-rich sediments. Deep-rooted tectonic control on gas migration is seen in the eastern study region with wide-spread normal faulting promoting gas migration. Overall, gas seepage is widespread along the margin. Gas migration appears more vigorous in shallow waters below ∼160 m water depth, but the number of flare sites is not necessarily an indicator of the total volume of gas released.

黑海的大陆斜坡在<720 m的水深中显示出大量的气体渗漏现象，但是对地下的控制仍未完全了解。在这里，我们使用声学多波束水柱，测深仪，反向散射和次底部剖面仪数据研究了保加利亚和罗马尼亚黑海沿岸的气体渗漏，以确定海底结构，海底气体渗漏和排入水柱中的气体之间的联系。 。约10,000 km ²范围内的10,000多个渗漏点被确定。气体渗漏的最大水深由结构I气体水合物稳定带在约720 m深度处的开始控制。但是，气体渗漏不是随机分布在其他地方。我们将控制气体渗流位置的三个因素分为沉积，侵蚀和构造因素。沉积因子与形成聚焦作用的区域性沉积物波和沉积物悬垂性有限的质量传输沉积物（MTD）有关。与断层和气体渗漏有关的伸长的海底凹陷在相邻的沉积物波之间的底部形成。细长的凹陷逐渐向浅水深度逐渐变宽和越来越深，并在某些位置达到顶点，形成麻点状簇。MTD覆盖更大的区域，并平整了古地形。它们的表面形态导致MTD顶部的沉积物悬垂的断层状变形模式，这些沉积物局部用于气体运移。在河道和峡谷以及坡度破坏中都观察到了侵蚀因素，在这些破坏中，沿头and和山脊发生了气体排放。被斜坡破坏除去的沉积物覆盖了较大的下坡区域。通过对气体迁移形成不可渗透的屏障或通过去除先前富含气体的沉积物，这些区域没有气体渗漏。在东部研究地区可以看到对天然气运移的根深蒂固的构造控制，正向断裂的广泛分布促进了天然气运移。总体而言，天然气渗漏沿边缘分布广泛。在水深约160 m以下的浅水区，气体迁移显得更为剧烈，