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Late Holocene Paleohurricane Reconstruction from the Central Texas Shelf, Western Gulf of Mexico, USA
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  • Sarah Monica,
  • Davin Wallace,
  • Sylvia Dee,
  • Elizabeth Wallace,
  • John Anderson
Sarah Monica
University of Southern Mississippi

Corresponding Author:[email protected]

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Davin Wallace
University of Southern Mississippi
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Sylvia Dee
Rice University
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Elizabeth Wallace
Rice University
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John Anderson
Rice University
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Abstract

Paleotempestology assists in extending the instrumental storm record through sedimentary-based, high-resolution records of storms over millennia. A fundamental understanding of the paleorecord provides essential context for modern climate models and, therefore, a broader understanding of our climate system. The Texas (TX) coastline receives the second largest number of hurricane landfalls per year in the United States; since 1900, 92 tropical storms and hurricanes have made landfall on the TX coast. During storm impacts, coastal downwelling storm channels deliver coarse sediment to the muddy shelf. This return flow or “backwash” process results in thin but expansive storm deposits in the region, making it ideal for paleotempestological reconstructions. In this work, three sediment cores from the central TX shelf, approximately six kilometers off the coast of Matagorda Island, were collected and analyzed. Several historic and Holocene storm events have been identified in cores by conducting detailed grain size analysis at one-centimeter intervals. Bayesian-based age models couple short-lived isotopic dating techniques (210-Pb and 137-Cs) with radiocarbon ages. X-ray fluorescence (XRF) analysis is used to determine geochemical signatures of the sediments and thus the material source for cross validating the depositional mechanism. Specifically, XRF is utilized to differentiate the effects of the 1929 Colorado River diversion relative to marine deposition. Our new record of tropical cyclone (TC) occurrence from the TX shelf is compared to paleoclimate models and proxy records of El Niño Southern Oscillation (ENSO) and Gulf of Mexico (GOM) sea surface temperature (SST). Preliminary results suggest that periods of decreased ENSO and increased GOM SST correspond with enhanced TX TC activity. Understanding these complex climatic interactions will help us to understand the changes in TC activity expected in the future against the background of accelerating climate change. Given that the frequency of extreme ENSO events is projected to increase, changes in the occurrence and severity of ENSO-TX TC events may prove detrimental to many coastal populations.