Landscape-Scale Morphology and Dynamics of Some Bahamian Ooid Shoals

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Coastal geomorphic-depositional systems represent the dynamic response of sediments to forcing mechanisms that operate across a range of spatio-temporal scales. Characterizing these systems is important for meaningful prediction in both modern coastal systems and for accurate stratigraphic interpretation of ancient analogs. In carbonate depositional systems, general sedimentologic criteria indicative of different facies are well documented, as are the general factors that control the regional distribution of these facies on carbonate platforms. What remains unclear are the details of the landscape-scale geomorphic and sedimentologic patterns within individual facies belts and bodies, the processes that influence these patterns, and possible feedbacks between process and product. In examining how sediments build into geomorphologic features which eventually may become the stratigraphic record, this intermediate scale represents a fundamental .missing link. between documentation of carbonate sediments and study of carbonate stratigraphy. To begin to fill this basic gap in understanding, this study proposes quantitatively examining the landscape-scale patterns and processes within some Bahamian ooid shoals, one carbonate depositional environment. Beyond the fact that these systems and the ooids forming them are inherently interesting, the locations chosen for this study also: a) have ancient analogs that form important water and hydrocarbon reservoirs; b) include ubiquitous lobate forms, geometries broadly analogous to some siliciclastic environments, allowing explicit comparison; and c) include lobes in both open-shelf and tidal delta settings, to permit assessing the generality of process-response dynamics in different conditions. We outline data collection and experiments to test several linked hypotheses related to modern carbonate ooid shoals and deltas, including: 1) at the landscape scale, the geomorphology of shoals is closely linked to spatial patterns of fluid flow; 2) the grain size, sorting, and type varies systematically and predictably within this hydro-geomorphic framework; and 3) lobes are a dynamically stable geomorphic configuration in many tide-dominated carbonate sand bodies in both tidal deltaic and more open shelf tide-dominated conditions. To address these hypotheses, this research will integrate remote sensing, bathymetric, grain size and sorting, grain type, and fluid flow data in a GIS,. In providing for quantitative characterization of these landscape-scale patterns and links to processes, these data will represent some of the first such analyses in carbonate systems. In exploring patterns and processes within oolitic tidal systems, this study will provide first-order predictive trends in morphodynamic evolution of shoals (.creating geobodies.) and quantitative links between geomorphic framework and grains (size, sorting) within shoals (.grains within geobodies.). Broader impacts. The application of new remote sensing, bathymetric and fluid flow analytical tools and quantitative integration of these data in a GIS represents a novel approach to study of landscape-scale sedimentologic-geomorphic systems. This approach should be broadly applicable to other environments, and we expect it will lead to a deeper understanding of geomorphic-depositional systems in general. In addition to training a Ph.D. student, this project includes educating underserved high school minority students about science, enhancing understanding of technology and environment in the local Bahamian community, and providing new learning tools and experiences for University of Miami students.