Woods Hole Oceanographic Institution

Dr Rob. L. Evans

»Electrical Structure of the Central Cascadia Subduction Zone: The EMSLAB Lincoln Line Revisited
»Electrical Lithosphere Beneath the Kaapvaal Craton
»Gulf Of Mexico Gas Seep
»MELT MT Results
»Wrightsville Beach Geophysics and Hydrology
»MELT Area Off-Axis Structure
»Karst Formation off North Carolina
»Review of Shallow Offshore EM Work
»Towed EM System
»EPR MMR Experiment
»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

Rob L. Evans, L.K. Law, B. St. Louis and S. Cheesman, Buried paleo-channels on the New Jersey continental margin: channel porosity structures from electromagnetic surveying, Marine Geol., vol 170, 2000

We report on a marine electromagnetic (EM) survey across two portions of the New Jersey continental margin that have been previously shown to contain buried paleo-channels. The EM method used provides bulk porosity estimates to depths of around 20 m below the sea?oor and is thus able to place porosity constraints on the nature of the channel in?ll and the contrast in physical properties across the channel boundaries. Our data show that a key condition for the channels to have an electrical signature is that they incise an underlying regional unconformity, R, thought to represent a subaerially eroded surface, exposed during the late Wisconsinan glaciation. Channels that cut R are seen through increases in apparent porosity. Another seismically imaged channel sequence, which lies within the outer-shelf sediment wedge sequence above R, does not have an electrical signature, indicating that the sediments above and below the channel boundaries have similar physical properties.

FILE » margeol_2000_7970.pdf

© Woods Hole Oceanographic Institution
All rights reserved