CALIBRATION AND APPLICATION OF MARINE SEDIMENTARY PHYSICAL-PROPERTIESUSING A MULTISENSOR CORE LOGGER

We examined geophysical data from a Multi-Sensor Core Logger (MSCL), a logging device providing continuous measurements of gamma-ray attenua tion, p-wave travel time, and magnetic susceptibility on marine sedime nt cores. In the first part we focused on the gamma-ray system and com pared two different calibration methods. From the gamma-ray attenuatio n, we calculated densities and porosities by incorporating mass weight ed attenuation coefficients. The application of an iteration method re duces the error of the density and porosity estimates compared to GRAP E data. In addition, we derived equations to calculate water content a nd dry bulk density from gamma-ray attenuation measurements. Compariso n with physical properties determined on discrete samples revealed a v ery good correlation of both data sets (r = 0.99). This correlation is valid for sediments from substantially different geological settings (e.g., turbidites, hemipelagic muds, and opal-rich sediments). In the second part we applied our data to marine geological questions. For se diments from the Antarctic Polar Frontal Zone, there is indication tha t the content of biogenic opal can be assessed using a correlation of density and p-wave velocity. For sediments from the Bengal Fan, the re lationship between the MSCL acoustic impedance (the product of density and p-wave velocity) and the grain-size distribution in discrete samp les can be used to predict clay and sand/silt ratios for sediment core s from the shelf and upper continental slope.