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The Quaternary Record: Isotopic Calibration of Sea-Level Change and Paleoclimate, New Jersey Cecilia M. G. McHugh 1,2 (718-997-3322; cmmqc@forbin.qc.edu) Hilary C. Olson 3 1S.E.E.S., Queens College, C.U.N.Y., 65-30 Kissena Blvd., Flushing, NY 11367, United States 2Lamont-Doherty Earth Observatory of Columbia University, Rt. 9W, Palisades, NY 10964, United States 3Institute for Geophysics, University of Texas, 4412 Spicewood Spring Blvd., Austin, TX 78759, United States Quaternary sediment recovered by the Ocean Drilling Program, Leg 174A from the New Jersey upper slope provides a record of sea-level change and paleoclimate. Site 1073 was drilled at 640 m of water depth as part of the New Jersey Mid-Atlantic Sea-Level Transect, a program dedicated to study the history of sea-level change on a passive margin. The selection of Site 1073 was based on seismic profiles to recover a complete Quaternary section to fill in previous gaps on the sea-level record that has been difficult to extract due to low carbonate taxa for biochronology, isotopic signatures, and $^{14}$C dating. Other problems encountered relate to the extent to which the continental slope is incised with submarine canyons and thick slump deposits that make it difficult to obtain long composite sections. Preliminary data indicated that the location of Site 1073 was also well suited for high resolution paleoclimatic studies: 1) the site was above the CCD to provide carbonate taxa; 2) seismic profiles showed that the wedge contained little re-deposited sediment; 3) the site was in a climatically sensitive location, 150 km away from the southern terminal moraine of the Laurentide Ice Sheet during the last glacial maximum. Iceberg scour marks imaged on the nearby shelf attest to the proximity of the ice sheet and to active glacial processes along this margin; and 4) the thickness of the seismic wedge suggested high sedimentation rates that optimize temporal resolution. The thick (520m) Quaternary section recovered permitted to construct an $\Delta$ $^{18}$O and biogenic opal curves that were calibrated with $^{14}$C chronology, nannoplankton biostratigraphy (Wei in prep), and magnetostratigraphy (Oda in prep). Results were correlated to the SPECMAP oxygen isotope time scale to: 1) document glacial and interglacial stages providing a paleoclimatic history of the region; 2) link unconformities identified from the sedimentary record and seismic lines to sequence boundaries and times of glacioeustatic lowerings; 3) identify a high-resolution paleoclimatic signal from the lithology, derived from x-ray diffraction (bulk mineralogy) and grain size analyses; and 4) provide a stratigraphic tool for future studies of the New Jersey continental margin. |
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