南海东北部陆坡天然气水合物区的滑塌和泥火山活动

Submarine slide and mud volcanism activities in gas hydrate bearing area on the northeastern slope,South China Sea

本文研究了南海东北部陆坡天然气水合物区滑塌和泥火山活动的特征及表现形式,探讨了滑塌和泥火山活动对天然气水合物成藏的影响,提出了滑塌主导和滑塌、泥火山共同作用两种控制模式。根据地震数据、浅层剖面和海底地形数据解释,将研究区划分为规则滑塌区和泥火山活动影响区,并识别出泥火山、泥火山脊、凹槽、凹坑等特征地形。滑塌和泥火山活动是陆坡天然气水合物发育区重要的地形控制因素,两种活动共同作用产生复杂的地形特征。综合多条地震测线中似海底反射层(BSR)形态、连续性和滑塌、泥火山活动的关系,认为滑塌控制的区域,BSR连续,天然气水合物储藏较完整,泥火山活动区天然气水合物储藏也仅受到局部破坏。同时指出滑塌和泥火山活动对研究区长期天然气渗漏活动具有重要作用。

In this paper, seabed morphology features related to submarine slide and mud volcanism activities are pres ented and analyzed,their impacts to gas hydrate formation and decomposition are discussed,and two models of slide driven and slide-mud volcano driven are proposed. Dataset used in this paper including seismic lines, sub-bottom profiler lines and bathymetry data obtained from seabed reflection picking. The study area consists of two main landforms： ＂regular slide region＂, and ＂mud volcanism activities affected region＂. We identify characteristic fea- tures such as mud volcano,mud volcano ridge,groove and pit from the bathymetry map. Submarine slide and mud volcanism activities play significant roles in affecting the morphology of the gas hydrate distribution region on the northeastern slope of South China Sea. Combining the analyses of BSR（Bottom Simulating Reflector） and mud volcanoes＇ distribution,relations between BSR discontinuity and mud volcano occurrence, we know that BSRs are continuous and gas hydrate reservoir is almost complete one in the regular slide region,while there is less and local destruction for the gas hydrate reservoir in the mud volcanism affected region slide and mud volcanism activities are important for long-term natural gas releasing process in the studied area.