FORMATION OF THE BOTTOM-SIMULATING REFLECTOR AND ITS LINK TO VERTICAL FLUID FLOW ...

• Main Authors: Haacke, R. Ross, Westbrook, Graham K., Hyndman, Roy D.
• Format: Text
• Language: English
• Published: The University of British Columbia 2008
• Subjects: Svalbard
• Online Access: https://dx.doi.org/10.14288/1.0040947; https://doi.library.ubc.ca/10.14288/1.0040947

Many places where natural gas hydrate occurs have a regionally extensive, bottom-simulating seismic reflector (BSR) at the base of the gas hydrate stability zone (GHSZ). This reflection marks the top of an underlying free-gas zone (FGZ). Usually, hydrate recycling (that produces gas as the stability field moves upward relative to sediments) is invoked to explain the presence and properties of the sub-BSR FGZ. However, this explanation is not always adequate: FGZs are often thicker in passive-margin environments where hydrate recycling is relatively slow, than in convergent-margin environments where hydrate recycling is relatively fast (e.g. Blake Ridge compared with Cascadia). Furthermore, some areas with thick FGZs and extensive BSRs (e.g. west Svalbard) have similar rates of hydrate recycling to northern Gulf or Mexico, yet the latter has no regional BSR. Here we discuss a gas-forming mechanism that operates in addition to hydrate recycling, and which produces a widespread, regional, BSR when gas is ...