Grain size and depositional environment as predictors of permeability in coastal marine sands |
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| Authors: | Alicia M Wilson Markus Huettel Stephen Klein |
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| Institution: | 1. Department of Geological Sciences, University of South Carolina, Columbia, SC 29208, USA;2. Department of Oceanography, Florida State University, Tallahassee, FL 32306, USA;3. Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, CO 80523, USA |
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| Abstract: | More than half of the surface sediments covering the continental shelves are sandy, which may permit substantial sub-seafloor pore water advection. Knowledge of sediment permeability is required for quantifying advection and associated solute transport, but studies of marine sediments typically report grain size analyses rather than permeability. Here data from 23 studies were examined to determine the range in permeabilities reported for sublittoral marine sands and to assess the utility of permeability–grain size relationships in this setting. In the resulting database, the permeability of small (∼30 cm) undisturbed cores collected from the sea floor all fell between 2 × 10−12 and 4 × 10−10 m2, a range where advective transport induced by wave and current action should be pervasive. The range in grain size was very similar for near-shore (<10 m water depth) and continental shelf samples (>10 m water depth), but the permeability of the continental shelf samples was consistently lower for the same median grain size. Empirical permeability–grain size relationships generated a poor fit (r2 = 0.35) for the aggregate data, but separate relationships for near-shore and continental shelf samples were significantly better, r2 = 0.66 and 0.77, respectively. Permeability–grain size relationships thus may be useful for sublittoral sands, but a larger database needs to be accumulated before reliable fit parameters and variability can be predicted. Thus it is recommended that permeability be routinely determined when characterizing sedimentological properties of marine sand deposits. Concurrent determinations of sediment bulk density and porosity may further improve estimates of permeability. |
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| Keywords: | marine sand deposits permeability grain size submarine groundwater discharge sublittoral |
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