Late Pleistocene New Jersey Shelf sedimentation as a response to glacio-eustatic sea level rise

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Title: Late Pleistocene New Jersey Shelf sedimentation as a response to glacio-eustatic sea level rise
Author: Stackhouse, Stanley B.
Abstract: Shallowly -buried channel systems have been imaged on the New Jersey Shelf with high -resolution seismic imaging . These channels formed as riverine systems that occupied the exposed shelf during the Last Glacial Maximum , ~18 ka . Subsequent sea level rise ~15 -12 ka modified the valleys , forming estuaries and filling the channels with estuarine sediments . The infill sediments within the channel provide evidence for the response of the shelf to the Late Pleistocene glacio -eustatic sea level rise , but little work has been done on samples from these strata . This study aids in the ground -truthing of previous stratigraphic results by analyzing the cores collected within the infill sediments . The seismic stratigraphy of fill sediments from the mid -shelf and outer -shelf channels are structurally dissimilar . The mid -shelf channel fill stratigraphy is dominated by finely -laminated U -shaped reflectors throughout the section , with cut and fill geometries . In contrast , the outer shelf channel fill stratigraphy is a well -ordered sequence of 4 identifiable , primarily flat -lying seismic units . We collected five cores in mid -shelf channels ( ~30 m water depth ) , one in an outer shelf channel ( ~80 m of water depth ) and one core in the trangressive ravinement surface . Cores were logged for density and seismic velocity . Grain size analysis was conducted by settling column and laser particle size analyzer . Radiocarbon analysis of the stratigraphy was conducted with the shell fragments and organic mud within the samples . The foraminiferal assemblages aided in determining the depositional environment . Using these data I investigated the differences in depositional environment of the mid - and outer -shelf channels systems , and consider these results in the context of sedimentary models for estuarine processes . The radiocarbon dates and foraminiferal are consistent with channel infill in an estuarine environment . Grain size and density log data indicate that the mid -shelf channel fills are sandier than the outer -shelf channel fills , which leads me to infer that the sediment from the mid -shelf channels was deposited in a higher energy environment than that of the sediment in the outer shelf channels . The stratigraphic differences and locations of the channel systems are similar to the Zaitlin (1994 ) model of incised valley infill , but infill of the mid -shelf channel system could possibly be the result of a catastrophic meltwater flood event occurring ~14 ka as glacial lakes to the north broke their dams and flooded the mid -shelf .
URI: http : / /hdl .handle .net /2152 /ETD -UT -2009 -08 -289
Date: 2010-06-04

Citation

Late Pleistocene New Jersey Shelf sedimentation as a response to glacio-eustatic sea level rise. Master's thesis, The University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /ETD -UT -2009 -08 -289 .

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