--> Abstract: Landscape-Scale Morphodynamics of Ooid Shoals, Lily Bank, Bahamas, by Eugene C. Rankey, Bernhard Riegl, and Kelley Steffen; #90039 (2005)

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Landscape-Scale Morphodynamics of Ooid Shoals, Lily Bank, Bahamas

Eugene C. Rankey1, Bernhard Riegl2, and Kelley Steffen1
1 Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL
2 Nova Southeastern University, Dania Beach, FL

In carbonate systems, sedimentologic criteria indicative of different subenvironments are well documented, as are the general factors that influence their distribution on carbonate platforms. In contrast, neither the sedimentologic patterns of individual geomorphic bodies nor the parameters influencing such patterns have been explored systematically, even though they represent a missing link between documentation of carbonate sediments and study of carbonate stratigraphy.

To begin to fill this basic gap in understanding, we quantitatively describe morphology and processes of a modern Bahamian ooid shoal. Integrating remote sensing imagery with quantitative geolocated bathymetric, fluid flow, and granulometric data in a GIS, we document geomorphic and sedimentologic patterns in an active shoal and explicitly link these patterns to the processes operating in this system.

The results reveal that parabolic bars form a common morphologic motif, although there is considerable variation on that general theme. The landscape-scale configuration of bars and superimposed sand waves is linked closely to patterns of tidal flows. Bars are not homogenous bodies, however, and granulometric parameters such as sorting and percentage mud vary systematically and predictably within this hydro-geomorphic framework, akin to siliciclastics.

In exploring oolitic shoals, this study provides new insights on details of their morphology and dynamics and in quantitative links between geomorphic framework and grain size and sorting within shoals. Assuming a continuity of processes between ancient and modern, the insights from this shoal provide information on possible facies geometries and on grain characteristics and depositional porosity in analogous facies in ancient ooid shoals.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005