Geophysical evidence of a late Pleistocene glaciation and paleo-ice stream on the Atlantic Continental Shelf offshore Massachusetts, USA

Siegel, Jacob; Dugan, Brandon; Lizarralde, D.; Person, Mark; DeFoor, Whitney; Miller, Nathaniel C.

doi:10.1016/j.margeo.2012.01.007

Cited by 21 publications

(30 citation statements)

References 64 publications

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“…U1 is an MIS 12 glacial unconformity formed by an ice stream. The bright spots overlie the U1 unconformity and are contained within a 50-75 m thick glacigenic sediment unit that was deposited during ice stream retreat [Siegel et al, 2012]. Scale bars on the right show relative amplitude for the seismic data.…”

Section: Geologic Settingmentioning

confidence: 99%

“…High sediment input during the Pleistocene, combined with sea level changes, produced a series of prograding clinoforms (Unit B1 in Figure 2). During the last sea level fall (40-30 ka), a shallow sequence boundary was formed (unconformity U2 in Figure 2) that is overlain by a combination of late Pleistocene and Holocene siliciclastic sediments [Siegel et al, 2012].…”

Section: 1002/2013jb010278mentioning

confidence: 99%

“…Permafrost can reduce the permeability beneath and beyond the extent of the ice sheet. However, because our study region is in a paleo-ice stream trough that exhibited signs of basal melting via subglacial drainage channels [Siegel et al, 2012], permafrost would not likely develop.…”

Section: Fluid Flowmentioning

confidence: 99%

“…Siegel et al [2012] show that the continental shelf off Massachusetts was glaciated in the late Pleistocene. Marksamer et al [2007] show that the Last Glacial Maximum (LGM) may have increased overpressure tens of kilometers beyond the maximum extent of the Laurentide ice sheet.…”

Section: Introductionmentioning

confidence: 97%

“…We then determine overpressure based on Figure 1. (a) Regional base map showing location of seismic lines used in this study along with the location of the maximum extent of the last glacial maximum (line labeled LGM) [Uchupi et al, 2001] and the inferred maximum extent of a MIS 12 ice sheet (black line labeled MIS 12) [Siegel et al, 2012]. The box shows the location of Figure 1b.…”

Section: Introductionmentioning

confidence: 99%

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Glacially generated overpressure on the New England continental shelf: Integration of full‐waveform inversion and overpressure modeling

et al. 2014

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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.

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Section: Geologic Settingmentioning

confidence: 99%

Section: 1002/2013jb010278mentioning

confidence: 99%

Section: Fluid Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Glacially generated overpressure on the New England continental shelf: Integration of full‐waveform inversion and overpressure modeling

et al. 2014

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

Siegel

Person

Dugan

et al. 2014

Geochem Geophys Geosyst

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Multiple late Pleistocene glaciations that extended onto the continental shelf offshore Massachusetts, USA, may have emplaced as much as 100 km 3 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.

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US Atlantic Margin Gas Hydrates

Ruppel

Shedd²,

Miller

et al. 2022

World Atlas of Submarine Gas Hydrates in Continental Margins

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Geophysical evidence of a late Pleistocene glaciation and paleo-ice stream on the Atlantic Continental Shelf offshore Massachusetts, USA

Cited by 21 publications

References 64 publications

Glacially generated overpressure on the New England continental shelf: Integration of full‐waveform inversion and overpressure modeling

Glacially generated overpressure on the New England continental shelf: Integration of full‐waveform inversion and overpressure modeling

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

US Atlantic Margin Gas Hydrates

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