HR: 0800h AN: T11B-1263 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