HR: 0800h
AN: T11B-1263    [Abstracts]
TI: A New Elastic-Viscous Model to Constrain Holocene Relative Sea Level Along the Northern Margin Gulf of Mexico
AU: * Zapata, R A
EM: rzapata@geol.lsu.edu
AF: Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803-4101 United States
AU: Lorenzo, J M
EM: juan@geol.lsu.edu
AF: Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803-4101 United States
AU: Blum, M D
EM: mike@geol.lsu.edu
AF: Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803-4101 United States
AU: Bart, P J
EM: pbart@geol.lsu.edu
AF: Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803-4101 United States
AU: Tomkin, J H
EM: tomkin@geol.lsu.edu
AF: Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803-4101 United States
AB: A variety of mid-to-late Holocene coastal deposits and landforms in the southern hemisphere, and along the US Gulf of Mexico coast, have been interpreted to represent one or more episodes of relative sealevel highstand, perhaps related to glacio-eustasy. For the US Gulf Coast, the sedimentary evidence for this highstand is highly variable, and contradicts high-resolution data from the Mississippi delta region, which shows continual submergence. However, possible alongshore variations in tectonic contributions to this record remain unclear. Global viscoelastic earth models exist to explain the vertical, crustal response to iceload changes and associated water loading (e.g., Peltier, 1974; Lambeck al., 1990). However, in the Gulf of Mexico case, a local model is needed, because of the presence of the Mississippi delta load anomaly, which is not considered in averaged earth global models. We develop a semi-analytical Green function approach for a new elastic-viscous flexure model consisting of an elastic plate over a viscous substratum. The solution is expressed as the Hankel transform of the load and lithosphere-mantle kernel. Over time this model converges to the equivalent response of an elastic plate over an inviscid substratum, which is in agreement with the elastic behavior of the lithosphere for long periods of time ($>10^6$yr). Predicted subsidence rates vary with distance to the load, and decrease over time. By incorporating the local sedimentary loading history, we make a first attempt to reconcile contradictory interpretations of mid-to-late Holocene relative sealevels, throughout the US Gulf of Mexico coast.
DE: 8105 Continental margins and sedimentary basins
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8160 Rheology--general
DE: 3210 Modeling
DE: 1236 Rheology of the lithosphere and mantle (8160)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting