Accession Number : ADA187477

Title :   Rapid Underway Sediment Classification by Electrical Methods.

Descriptive Note : Final rept.,

Corporate Author : NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY NSTL STATION MS

Personal Author(s) : Valent, Philip J ; Mozley, Edward C ; Corwin, Robert F

PDF Url : ADA187477

Report Date : Aug 1987

Pagination or Media Count : 74

Abstract : The initial results of a technical feasibility study for using direct current (DC) electric resistivity, electromagnetic (EM), and induced polarization (IP) methods to classify surficial sea floor sediments are reported. Analytical work performed in this study and a review of related work show that both the DC and EM resistivity techniques can provide electrical measurements of sufficient resolution to classify sediments according to type (mud, clay, silt, sand, gravel, etc.). Both DC and EM antennas must be close to the sea floor surface (within 10m) so that surficial sediment resistivities can be sufficiently resolved to permit sediment classification. To resolve the resistivity of a 1-m thick surficial sea floor sediment layer, the DC antennas must be deployed less than 1/m above the seafloor. Both DC and EM methods can adequately resolve the resistivity of a 6-m thick surficial layer at a standoff distance of 10/m. Noise tests with an inverted Schlumberger array towed in the water column and on the sea floor show noise levels to be within acceptable limits. The level of development of the IP method for clay mineral detection is reported; this method shows considerable promise as a contributor to a remote underway sediment classification system. Keywords: Sediments, Electrical conductivity; Direct current resistivity.

Descriptors :   *CLASSIFICATION, *ELECTRICAL MEASUREMENT, *SEDIMENTS, ANTENNAS, CLAY, DETECTION, DIRECT CURRENT, ELECTRICAL CONDUCTIVITY, ELECTRICAL PROPERTIES, ELECTRICAL RESISTANCE, ELECTROMAGNETIC RADIATION, FEASIBILITY STUDIES, GRAVEL, LAYERS, LEVEL(QUANTITY), MINERALS, MUD, NOISE, OCEAN BOTTOM, SURFACES, POLARIZATION, SAND, SILT, WATER, ELECTROMAGNETIC PROPERTIES, STANDOFF, SHORT RANGE(DISTANCE), TOWED ARRAYS, OCEANOGRAPHIC EQUIPMENT

Subject Categories : Physical and Dynamic Oceanography
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE