Adam Skarke - SMSP Fall Seminar Series 2026

Adam Skarke

Abstract: Seafloor seeps are locations where gas (primarily methane) is discharged from marine sediments into the ocean. They are widely recognized as an important component of the global carbon cycle because they directly link vast methane reserves in subseafloor sediments to the marine environment. Methane released at seeps drives a wide range of interconnected biogeochemical processes in the shallow subsurface, at the seafloor, and in the overlying water column. These processes contribute to ocean acidification and deoxygenation but also result in extraordinary hotspots of deep-sea benthic biodiversity with unique authigenic rock outcrops that harbor complex chemosynthetic ecosystems. Additionally, gas seeps indicate the potential for significant marine geohazards and are a demonstrated energy exploration and production resource. Geophysical analysis of water column backscatter data has revealed the presence of approximately 1,300 seeps on the US Atlantic margin between Cape Hatteras and Cape Cod. As a function of depth, seep distribution is heavily skewed toward the upper continental slope at water depths shallower than 400 m on the southern New England margin and ~ 550 m in the Mid-Atlantic Bight, with additional seeps clustered at ~1,100 m and just deeper than ~1,400 m in both sectors. Despite little ongoing tectonic deformation or active faulting on this passive margin, a variety of geologic and geomorphologic processes driven from below the seafloor (e.g., migration of fluids along faults or through permeable strata, seepage above diapirs, or other pre-existing structures) and from above (e.g., erosion, sapping, unroofing) contribute to the development of seeps in different settings along the margin. This talk will review the discovery of these seeps and present an interpretive geological framework for the US Atlantic margin seep province as well as the development of novel geophysical data processing approaches to improve seep detection and recent results from interdisciplinary investigation of select seep sites.