Glacially generated overpressure on the New England continental shelf : integration of full-waveform inversion and overpressure modeling
MetadataShow full item record
Localized zones of high-amplitude, discontinuous seismic reflections 100 km off the coast of Massachusetts, USA, have P wave velocities up to 190 m/s lower than those of adjacent sediments of equal depth (250 m below the sea floor). To investigate the origin of these low-velocity zones, we compare the detailed velocity structure across high-amplitude regions to adjacent, undisturbed regions through full-waveform inversion. We relate the full-waveform inversion velocities to effective stress and overpressure with a power law model. This model predicts localized overpressures up to 2.2 MPa associated with the high-amplitude reflections. To help understand the overpressure source, we model overpressure due to erosion, glacial loading, and sedimentation in one dimension. The modeling results show that ice loading from a late Pleistocene glaciation, ice loading from the Last Glacial Maximum, and rapid sedimentation contributed to the overpressure. Localized overpressure, however, is likely the result of focused fluid flow through a high-permeability layer below the region characterized by the high-amplitude reflections. These high overpressures may have also caused localized sediment deformation. Our forward models predict maximum overpressure during the Last Glacial Maximum due to loading by glaciers and rapid sedimentation, but these overpressures are dissipating in the modern, low sedimentation rate environment. This has important implications for our understanding continental shelf morphology, fluid flow, and submarine groundwater discharge off Massachusetts, as we show a mechanism related to Pleistocene ice sheets that may have created regions of anomalously high overpressure.
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 119 (2014): 3393–3409, doi:10.1002/2013JB010278.
Suggested CitationArticle: Siegel, Jacob, Lizarralde, Daniel, Dugan, Brandon, Person, Mark, "Glacially generated overpressure on the New England continental shelf : integration of full-waveform inversion and overpressure modeling", Journal of Geophysical Research: Solid Earth 119 (2014): 3393–3409, DOI:10.1002/2013JB010278, https://hdl.handle.net/1912/6773
Showing items related by title, author, creator and subject.
Meridional circulation during the Last Glacial Maximum explored through a combination of South Atlantic δ18O observations and a geostrophic inverse model Gebbie, Geoffrey A.; Huybers, Peter (American Geophysical Union, 2006-11-15)The vertical profile of meridional transport in the South Atlantic is examined by combining paleoceanographic observations with a geostrophic circulation model using an inverse method. δ18Ocalcite observations along the ...
Amrhein, Daniel E.; Wunsch, Carl; Marchal, Olivier; Forget, Gael (American Meteorological Society, 2018-08-28)We use the method of least squares with Lagrange multipliers to fit an ocean general circulation model to the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) estimate of near sea surface ...
Gebbie, Geoffrey A.; Peterson, Carlye D.; Lisiecki, Lorraine E.; Spero, Howard J. (2015-08)A paleo-data compilation with 492 δ13C and δ18O observations provides the opportunity to better sample the Last Glacial Maximum (LGM) and infer its global properties, such as the mean δ13C of dissolved inorganic carbon. ...