HR: 1330h
AN: OS52B-0907    [PDF]
TI: LATE PLEISTOCENE DEPOSITIONAL ENVIRONMENTS OF THE NEW JERSEY CONTINENTAL SHELF: FORAMINIFERAL EVIDENCE
AU: * Christensen, B A
EM: bchristensen@gsu.edu
AF: 1. Department of Geology, Georgia State University, PO Box 4105, Atlanta, Ga 30302-4105 United States
AU: Goff, J A
EM: goff@utig.ig.utexas.edu
AF: 2 University of Texas Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, 4412 Spicewood Springs Road, Bldg. 600,, Austin, TX 78759-8500 United States
AU: Alexander, C R
EM: clark@skio.peachnet.edu
AF: 3. Skidaway Institute of Oceanography,, 10 Ocean Science Circle, Savannah, Ga 31411 United States
AU: Austin, J A
EM: jamie@utig.ig.utexas.edu
AF: 2 University of Texas Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, 4412 Spicewood Springs Road, Bldg. 600,, Austin, TX 78759-8500 United States
AU: Gulick, S P
EM: sean@utig.ig.utexas.edu
AF: 2 University of Texas Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, 4412 Spicewood Springs Road, Bldg. 600,, Austin, TX 78759-8500 United States
AU: Fulthorpe, C S
EM: craig@utig.ig.utexas.edu
AF: 2 University of Texas Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, 4412 Spicewood Springs Road, Bldg. 600,, Austin, TX 78759-8500 United States
AU: Nordfjord, S
EM: sylvia@ig.utexas.edu
AF: 4. University of Texas at Austin, Department of Geological Sciences, John A. and Katherine G. Jackson School of Geosciences,, 1 University Station C1100,, Austin, TX 78712 United States
AU: Sommerfield, C
EM: cs@udel.edu
AF: 5. College of Marine Studies, University of Delaware,, 700 Pilottown Road, Lewes, DE 19958-1298 United States
AU: Venherm, C
EM: claudia@skio.peachnet.edu
AF: 3. Skidaway Institute of Oceanography,, 10 Ocean Science Circle, Savannah, Ga 31411 United States
AU: Schock, S
EM: sschock@fau.edu
AF: 6. Department of Ocean Engineering, Florida Atlantic University,, 777 Glades Road,, Boca Raton, FL 33431 United States
AU: Nielson, D L
EM: dnielson@dosecc.org
AF: DOSECC, Inc.,, 675 South Arapeen Drive, Suite 201, Salt Lake City, UT 84108 United States
AB: The glacial- interglacial history of the New Jersey shelf is difficult to unravel because of associated erosion. Drilling on the NJ slope (ODP Leg 150) penetrated thick sequences of displaced sediments, deposited as the shoreline shifted seaward. Subsequent attempts at recovery of shelf sediments (ODP Leg 174A) were less successful because the variable lithologies resulting from the discontinuous nature of deposition on the Pleistocene NJ shelf made continuous recovery difficult. As part of a long term ONR initiative (STRATAFORM, GEOCLUTTER), grab samples have been recovered to identify surface and shallow subsurface geologic features, and high resolution seismic reflection data (CHIRP) were collected to image the shallow subsurface. Most recently, long cores have been recovered to verify interpretations of seismic reflection data using an innovative Active Heave Compensated drilling system supplied by DOSECC. Core catcher samples from nearly continuous long cores (Sites 1-3) have been analyzed for foraminiferal content (benthic and planktonic) to determine environment of deposition, and stratigraphic position. Subsurface lithology varies but generally consists of sands, shell hash, and/or bioturbated clays. Benthic foraminiferal assemblages are in agreement with bathymetry and facies. For example, the bioturbated clay present at the deepest water Site 1 ($\sim$ 129 m water depth) contains a diverse assemblage, including abraded and transported specimens, but also {\it in situ} components. However, the sediments at Site 2 (($\sim$ 80 m water depth) contain a bimodal population: inner - middle neritic sands, as indicated by abundant {\it Elphidium} spp., and a fluvial- dominated system, as suggested by common pebbles, metamorphic rock fragments, abundant mica, and wood and shell fragments. Grab samples, collected at sites identified from detailed bathymetric and backscatter analyses, have also been analyzed for foraminiferal content to assess the environment of deposition and to evaluate reworking. Samples have been analyzed both on and adjacent to features such as gravel lags, sand ridges, and erosion pits. Both the fauna and the mineralogy are varied and reflect the high degree of variability of surface morphology. Generally, the foraminiferal populations are bimodal, with an {\it in situ} component, and another assemblage of very abraded, reworked foraminifera. The mineralogy also reflects at least two populations and includes abundant clear angular quartz, and reworked rounded, frosted, often iron- stained quartz. The presence of lithic fragments, coupled with a variable lithology, together suggest that some of these grains may be ice rafted debris (IRD), although it is difficult to differentiate between reworked shelf sediments and IRD.
DE: 3022 Marine sediments--processes and transport
DE: 3030 Micropaleontology
DE: 4267 Paleoceanography
DE: 8105 Continental margins and sedimentary basins
DE: 9350 North America
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting