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GEOPHYSICAL RESEARCHES ON MARINE GAS HYDRATES（Ⅳ）：DOUBLE BOTTOM SIMULATING REFLECTIONS
SONG Haibin，JIANG Weiwei，ZHANG Ling
（Institute of Geology and Geophysics，CAS，Beijing 100029，China）
Abstract：Researches on double bottom simulating reflections（double BSRs）are very important becausethey may indicate the characteristicsof dynamic evolution of gas hydrate and free gas system.By now there are two typical double BSR distribution regions，one is western Norwegian margin and the other is eastern Nankai Trough margin.Usually there are two potential explanations for the double BSR.First，it can be explained to be a relict gas-hydrate BSR，a reflection from the base of gas hydrate stability zone of a paleoset of pressure and temperature conditions.Second，it can be explained to be a reflection from the base of gas hydrate bearing sediments with a mixturegas of composition.It will provide critical information for better understanding of gas hydrate formation mechanism，its distribution law and evolution in geological history to study spatial distribution characteristics and the origin of double BSR and set up model of dynamic evolving gas hydrate and free gas system
Keywords：Gas hydrate system；Seismic methods；Double BSR；Bottom simulating reflections；Stability zone
