THE CHARACTERISTICS AND IMPLICATIONS OF SUBMARINE HYDRATE PINGO

Submarine hydrate pingo is a special kind of seabed topographic features, whose appearances vary from smooth, well-rounded, steep-sided mounds to rough, uneven, gently dipping mounds. Submarine hydrate pingo usually emerges as blank reflection in seismic profiles, and is closely related with bottom-simulating reflection (BSR). This paper summarizes the previous researches on the submarine hydrate pingo. On this basis, we believe that, the relatively large-scale submarine hydrate pingo is usually formed adjacent to high-flux focused fluid migration pathway; the occurrence of submarine hydrate pingo possibly indicates the occurrence of hydrate and hydrocarbon reservoir under the pingo, and the continental margin focused-fluid migration. At the same time, in the function of focused-fluid migration, upward migration of heat flow and highly saline fluids may result in the shoaling of BSR. Furthermore, the formation and evolution of submarine hydrate pingo is a dynamic process, conducted in an open flow system, which is divided into three phases, including hydrate nucleation, hydrate aggregation/pingo formation, and hydrate dissociation/pingo collapse. The gases of hydrate pingo formed in the open flow system are derived from external fluid after "deep" sediment percolation, which can form hydrate deposits with larger-scale and high saturation, and have the exploration value. To better understand the evolution history of submarine hydrate pingo, and the relationship between submarine hydrate pingo and focused migration pathway as well as the location of BSR distribution, more seabed survey and high-resolution multi-channel seismic survey should be carried out, and a comprehensive evaluation should be conducted combined with geochemical methods.