Techniques: Sediment physical properties such as susceptibility, conductivity, porosity, density, sound velocity, and color are controlled by sediment composition and fabric. These parameters are fundamental as well for geophysical exploration as for the description, correlation and stratigraphy of sediment cores. We conduct core logging and imaging on board of reserach vessels and in our own core logging laboratory.
System: The GEOTEK Multi Sensor Core Logger (MSCL) operated by the Marine Geophysics Group is equipped with a magnetic susceptibility coil sensor (Bartington MS2C, diameter 140 mm) with an operating frequency of 565 Hz and effective resolution of 2 x 10E-6 SI. Due to its size, the sensor integrates the response signal over a core interval of about 8 cm.
Data from a non-contact resisitivity sensor (NCR) is taken to calculate sediment porosity and wet bulk density.
For inductive porosity and susceptibility proxies, we join the core segment data to an entire core log due to a method-immanent nonlinear signal decay toward the segment caps. Corrections using an adapted core end correction curve are applied.
Furthermore, a digital RGB line scan camera GEOSCAN II containing three 1024 pixel CCD arrays is mounted which allows for measurement of light and color reflectance and to obtain digital photographs of the surface of split cores. A specific image analysis program is used to remove end-caps, cavities and other disturbances from the raw image data before post-processing.
System: A magnetic susceptibility logger is available which is equipped with a Bartington MS2 susceptibility meter that is connected either to a MS2E or a MS2F spot sensor. Both sensors are used for the measurements of either split core sections of 1 m length or u-channels of 1.5 m length.
The measurement interval can be set at increments of 1 millimeter considering that the physical spatial resolution of both sensors is in the order of several millimeters (MS2E) or a few centimeters (MS2F). Applying our standard protocol it will take about 50 minutes to measure a 1 m section at 1 cm increment. Each measurement on the sediment surface is completed by a respective reference measurement 'in air' in order to correct for an instrumental drift during post-processing.
System: This spectrophotometer determines the diffuse reflectance of rock surfaces in the extended visible light spectrum of 360-740 nm (10 nm intervals) over area of 8 resp. 3 mm (Ã). The manual system is useful for the lithostratigraphic analysis of split cores and cube samples, in particular to measure the abundance of pigmented minerals such as hematite, goethite, coal, clay etc. A new endmember modelling technique for such data was developed by our group (Heslop et al. 2007) and used to detect dust and diagenetic layers in sediment cores.