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Woods Hole Oceanographic Institution

Dr Rob. L. Evans

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Publications
»Electrical Lithosphere Beneath the Kaapvaal Craton
»Gulf Of Mexico Gas Seep
»MELT MT Results
»MELT Area Off-Axis Structure
»Wrightsville Beach Geophysics and Hydrology
»Karst Formation off North Carolina
»Review of Shallow Offshore EM Work
»EPR MMR Experiment
»Towed EM System
»Offshore MT and Subduction Systems
»Shallow Porosity Structure on the Continental Shelf
»Oceanic and Continental Mantle Resistivity
»New Jersey EM Survey
»Eel River EM Survey
»Impact of groundwater on EM data
»Electrical structure of Slave Craton
»Report of Shoreline Change Workshop


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Michelle Ellis, Rob. Evans, Deborah Hutchinson, Pat Hart, Joan Gardner, Rick Hagen. , Electromagnetic Surveying of Seafloor Mounds in the Northern Gulf of Mexico
, Marine and Petroleum Geology, 2008

Seafloor controlled source electromagnetic data, probing the uppermost 30m of seafloor sediments, have been collected with a towed magnetic dipole-dipole system across two seafloor mounds at approximately 1300 m water depth in the northern Gulf of Mexico. One of these mounds was the focus of a recent gas hydrate research drilling program. Rather than the highly resistive response expected of massive gas hydrate within the confines of the mounds, the EM data are dominated by the effects of raised temperatures and pore fluid salinities that result in an electrically conductive seafloor. This structure suggests fluid advection towards the seafloor is taking place beneath both mounds. Similar responses are seen at discrete locations away from the mounds in areas that might be associated with faults, further suggesting substantial shallow fluid circulation. Raised temperatures and salinities may inhibit gas hydrate formation at depth as has been suggested at other similar locations in the Gulf of Mexico.

 

Reference: Ellis et al., Marine and Petroleum Geology, 25, 960-968, 2008

 


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