摘要
Gas hydrate samples were first obtained in the Dongsha area,South China Sea(GMGS2)in 2013.High-resolution 3D seismic data in the area show various small 1andslide bodies developedas huge mass transport deposits.These bodies are divided into seven types on the basis of theirshapes,intermal structures and geneses(slide,collapse and deformation above BSRs,as well asthe slump wedge,lens,block and sheet below BSRs).Based on this classification,detailed studieswere conducted,including measurements of the slump body sizes and slope gradients of landslides,depiction of their three-dimensional characteristics,and research on the landslide distribution.Todetermine the genetic differences of these seven types,this study analyses the possibility of verticalflow-pattern-transformation and mechanisms of submarine landsltide formation.Results show that thedominant factor influencing the submarine landslides in the Dongsha area is the free gas emitted fromgas hydrate decomposition,with possible fransformation between flow patterns.Finally,there are twokinds of relationships between submarine landslides and BSRs since the free gas either influences thesubmarine landslide bodies below or above BSRs,resulting in two types of submarine landslide bodyassociations:Type A is characterized by submarine slide above BSRs and slump lens below BSRs,whereas Type B shows deformation above BSRs and slump blocks below BSRs.Type Ais favourablefor gas exploration because it indicates less decomposition and better sealing of gas hydrate layers.
