HR: 17:00h
AN: H34B-05    [Abstracts]
TI: Using Paleocoastal Features to Model Epeirogenic Uplift History and Karstification of North Florida
AU: * Adams, P N
EM: adamsp@ufl.edu
AF: University of Florida, Dept. of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611,
AU: Jaeger, J M
EM: jaeger@geology.ufl.edu
AF: University of Florida, Dept. of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611,
AU: Opdyke, N D
EM: drno@nersp.nerdc.ufl.edu
AF: University of Florida, Dept. of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611,
AU: Martin, J B
EM: jmartin@geology.ufl.edu
AF: University of Florida, Dept. of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611,
AU: Hodell, D A
EM: hodell@ufl.edu
AF: University of Florida, Dept. of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611,
AB: Pleistocene beach ridges oriented sub-parallel to the modern U.S. Southeast Atlantic coastline reflect a rich history of nearshore sediment accumulation and sea level oscillation. These features are preserved at elevations up to ~50 meters above modern sea level suggesting regional uplift has occurred, despite the tectonically quiescent setting. Previous studies have proposed the combination of near surface karstification of the upper portion of the Florida carbonate platform and isostatic response as a mechanism to explain regional uplift. Measurements of dissolved solids in Florida's springs correspond to a carbonate rock dissolution rate sufficient to uplift the Florida platform at a rate of ~0.03 mm/yr. We present a simple numerical model that combines (i) sea level oscillation, (ii) precipitation induced- karstification, and (iii) isostatic response to change in bulk crustal density to calculate the elevation history of a prominent beach ridge (Trail Ridge) and coastal marine terrace (Penholoway Surface) in North Florida from the early Pleistocene to present. Using the assumption that beach ridge formation occurs during sea level highstand events, the model enables us to test various combinations of paleo-precipitation history and karstification function for a known eustatic sea level history. Preliminary model simulations verify the hypotheses that (1) paleo-precipitation history is positively correlated with sea level fluctuation (higher precipitation during warm climate intervals), as indicated by lake core studies, and (2) carbonate rock dissolution rates may be lower now than in the past due to more efficient flushing of groundwater undersaturated with respect to carbonate through well-developed secondary porosity in karst terrain.
DE: 1130 Geomorphological geochronology
DE: 1824 Geomorphology: general (1625)
DE: 3010 Gravity and isostasy (1218, 1222)
DE: 4217 Coastal processes
SC: Hydrology [H]
MN: 2007 Fall Meeting