Permeability-Porosity Patterns of Some Recent Sediments: ABSTRACT

Abstract

Permeability, porosity, and textural analyses were conducted on 1,016 sand samples collected from river point bars, beaches, and dune fields undergoing active sedimentation. A total of 326 samples are from point bars on the Whitewater River in southwestern Ohio and the Wabash River in western Indiana; 531 samples are from beaches on the Bolivar Peninsula in Texas, Ship Island in Mississippi, and Santa Rosa Island in Florida; and 159 samples are from dunes on Santa Rosa Island and St. Andrew's Beach in Florida. River point-bar sand samples have permeability values ranging from 160 md to more than 500 d and average 93 d. Porosity values range from 17 to more than 50 percent, and average 38. Permeability-porosity values for point bars are highly variable and show a systematic pattern related to positions on the bars. Beach and dune sand samples have very similar permeability values, which range from 3,600 md to 166 d and average 60 d. Porosity values range from 30 to more than 65 percent, and average 45. Permeability-porosity values for beaches and dunes show a low variability and a poorly developed pattern related to positions within the environments. Permeability and porosity values in all three depositional environments have low correlations with textural parameters. In some point-bar sands, high percentages of silt and clay account for low permeability values. However, high permeability and porosity in river-bar, beach, and dune sands are not well correlated with large grain sizes and good sorting; instead, packing seems to be the primary controlling factor. Comparison of permeability-porosity values of these Recent sediments with available values from comparable ancient sediments shows that the Recent sediment values are several orders of magnitude higher; however, Recent sediments do show the same degrees of variability and distribution patterns as those in the ancient sediments. End_of_Article - Last_Page 546------------