Bottom-Simulating Seismic Reflectors (BSRs)
A seismic reflection occurring in the upper few hundred meters of marine sediments mimicking the seafloor, crosscutting sediment layers, and showing a phase reversal is known as a “bottom-simulating reflector.” Such a gas hydrate-related BSR originates from a large impedance contrast between a layer of gas-hydrated sediment above and a free gas layer below. A diagenetic-related BSR occurs at the opal-A/opal-CT transition zone, lies often deep and outside the base of the gas hydrate stability zone, shows no phase reversal, and does not always mimic the seafloor.
The intent of this article is to describe the two most commonly observed bottom-simulating reflectors (BSRs). The term BSR stems from their principal characteristic that these reflectors mimic the seafloor topography in marine seismic reflection data thereby crosscutting sedimentary strata. BSRs are known to occur in continental margin sediments in regions of gas hydrate and free gas (Shipley et al., 1979...
KeywordsInstantaneous Frequency Impedance Contrast Methane Hydrate Blake Ridge Polygonal Fault
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