Spectrum gamma ray borehole logging of MeBo sediment core GeoB23731-2 (first run)

Logging was performed with the sea floor drill rig MARUM-MeBo70 in a borehole drilled with a 103 mm diameter bit. The 1460 Slimhole Memory SGR instrument developed by ANTARES Datasystems GmbH was used. A CsI(Na) crystal with outer diameter of 37 mm and 250 mm length is used as detector. The probe provides Natural Gamma Ray counts and analyses the spectrum for the concentrations of the natural gamma ray emitters potassium, thorium and uranium with an accuracy of about 10%. The probe was deployed in the memory mode with the logging string being inserted into the drill string. The measurement was conducted as upcast hooking up the logging string with a wire inside the drill string. This was the first of two subsequent runs. Wire speed was about 9 cm/s and the logging frequency was 0.5 Hz. Data Processing including the correction for bore hole diameter and signal attenuation by the drill string was conducted using the Antares software GeoBase 6.22.