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2007 GSA Denver Annual Meeting (28–31 October 2007)

Paper No. 4
Presentation Time: 8:00 AM-12:00 PM

REVISITING OXYGEN ISOTOPE STAGE 3 AND 5A (OIS3-5A) SEA LEVELS WITHIN THE NORTHWESTERN GULF OF MEXICO


SIMMS, Alexander R., School of Geology, Oklahoma State University, 105 Noble Research Center, Stillwater, OK 74078, REGINA, Kalchgruber, Department of Physics, Oklahoma State University, 145 Physical Sciences, Stillwater, OK 74078, RODRIGUEZ, Antonio B., Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557, LAMBECK, Kurt, Research School of Earth Sciences, The Australian National Univ, Mills Road, Canberra, ACT0200, Australia and ANDERSON, John B., Department of Earth Sciences, Rice University, 6100 Main Street, Houston, TX 77005, alex.simms@okstate.edu

Based on the present elevation of shallow-marine environments, previous studies along the northwestern Gulf of Mexico including data from the Freeport Rocks Bathymetric High, offshore Texas, suggest that sea-level during oxygen isotope stage 3 (OIS3) was as high as -15 m. This value is in conflict with oxygen-isotope proxies and other measurements of sea level from across the globe during this time period. We revisit this problem by running glacio-isostatic models to determine if an OIS3 value of -15 m is within the realm of possibilities given our current knowledge of global sea-levels. In addition, we present new optically stimulated luminescence (OSL) dates on relict shoreline deposits to determine their absolute age. We find that, using more recent estimates of the global meltwater volume during OIS3 plus glacio-hydro-isostatic corrections, a -15 m elevation for the OIS3 shoreline within the Gulf of Mexico is within the range of possibility. However, our OSL dates show that the Freeport Rocks Bathymetric High, originally postulated as an OIS3 deposit, is an OIS5a deposit with an age of 90.7+/-5.5 ka. Based on these deposits and their relationship to former sea levels, we provide one of the first estimates for OIS5a sea levels within the northwestern Gulf of Mexico of around -11 m. Our work does not preclude the possibility of high OIS3 sea levels in other places along the Texas shelf.

Session No. 25--Booth# 48

Marine/Coastal Science (Posters)
Sunday, 28 October 2007: 8:00 AM-12:00 PM
Geological Society of America Abstracts with Programs. Vol. 39, No. 6, p.67
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