| Summary: | This study is concerned with the relationships between electrical resistivity and the bulk physical properties of sea floor sediment. Electrical resistivity was measured in gravity-cored, unconsolidated sediments from the Bering Sea. These sediments were olive green to black silty clays to sands, with a thin brownish cover in the central basin. They contained up to 20% clay minerals and less than 1% metallic minerals. Biogenic fractions consisted mainly of diatoms with minor amounts of radiolarians, spicules, and foraminifers. Porosity appeared to be inversely related to the silt size fraction, and directly to the phi deviation measure and clay size fraction. The relationship between porosity and phi deviation measure was probably secondary with the primary influence contributed by the clay size fraction. Resistivity ranged from 29.1 to 71.0 ohm-cm at 25° C and irregularly increased 11 ohm-cm within the first meter below the sediment surface, principally because of porosity changes. In situ resistivity may be greater than these laboratory values by a factor up to 2. The formation factor (F), ratio of sediment resistivity to interstitial water resistivity, ranged from 1.57 to 3.70 and was related to porosity (ϕ) and wet bulk density (ρ), respectively by: F = 1.30 ϕ-1.45 and F = 1.13ρ1.72 with errors of ± 15% and ± 10%. Within certain limits resistivity may be used to estimate other physical properties of the sediment. San Diego State University
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