Marine pore-water sulfate profiles indicate in situ methane flux from underlying gas hydrate

Abstract

Marine pore-water sulfate profiles measured in piston cores are used to estimate methane flux toward the sea floor and to detect anomalous methane gradients within sediments overlying a major gas hydrate deposit at the Carolina Rise and Blake Ridge (U.S. Atlantic continental margin). Here, sulfate gradients are linear, implying that sulfate depletion is driven by methane flux from below, rather than by the flux of sedimentary organic matter from above. Thus, these linear sulfate gradients can be used to quantify and assess in situ methane flux, which is a function of the methane inventory below.