Design and application of a new free fall in situ resistivity probe for marine deep water sediments

We have developed a new type of sediment penetrating in situ probe which lo gs electrical resistivity in marine and limnic sediments in the uppermost 3 .5 m. As the instrument is fitted to a Lister-type heat-flow instrument, co mbined thermal and electrical conductivity measurements are possible. The p robe incorporates no moving mechanical parts, is built to operate in water- depths up to 4000 m and is relatively easy to deploy. Two separate electrod e arrays provide for an instant repeatability test and rapid data quality a ssessment. The probe was extensively tested in the laboratory. Field tests in Lake Konstanz and in the North Sea produced consistent results. This pap er gives a description of the design of the probe and the test results. A t heoretical derivation of the probe's configuration factor is presented and theoretical results are verified in laboratory tests. (C) 1999 Elsevier Sci ence B.V. All rights reserved.