Influence of late Pleistocene glaciations on the hydrogeology of the continental shelf offshore Massachusetts, USA

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Siegel, Jacob, Person, Mark, Dugan, Brandon, Cohen, Denis, Lizarralde, Daniel, Gable, Carl
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2014
• Subjects: Pleistocene; hydrogeology; continental shelf; glaciation; freshwater resources; Ice Sheet
• Online Access: https://hdl.handle.net/1911/78904; https://doi.org/10.1002/2014GC005569

Multiple late Pleistocene glaciations that extended onto the continental shelf offshore Massachusetts, USA, may have emplaced as much as 100 km3 of freshwater (salinity <5 ppt) in continental shelf sediments. To estimate the volume and extent of offshore freshwater, we developed a three-dimensional, variable-density model that couples fluid flow and heat and solute transport for the continental shelf offshore Massachusetts. The stratigraphy for our model is based on high-resolution, multichannel seismic data. The model incorporates the last 3 Ma of climate history by prescribing boundary conditions of sea level change and ice sheet extent and thickness. We incorporate new estimates of the maximum extent of a late Pleistocene ice sheet to near the shelf-slope break. Model results indicate that this late Pleistocene ice sheet was responsible for much of the emplaced freshwater. We predict that the current freshwater distribution may reach depths up to 500 meters below sea level and up to 30 km beyond Martha's Vineyard. The freshwater distribution is strongly dependent on the three-dimensional stratigraphy and ice sheet history. Our predictions improve our understanding of the distribution of offshore freshwater, a potential nonrenewable resource for coastal communities along recently glaciated margins.