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MARUM-MeBo borehole logging

Not only are the drilled cores but also the boreholes themselves an important instrument of geoscientific investigation. Borehole logging can be used for gaining sets of continuous profiles of in‐situ measured petrophysical parameters. Such data is used to construct a lithological profile and to correct depth of the acquired drill cores. An autonomous memory probe developed by the company Antares Datasystems GmbH belongs to the MARUM-MeBo system and can be deployed both with MeBo70 and MeBo200. This probe is deployed in the logging while tripping mode. After reaching the target depth the memory probe is dropped into the drill string. While the drill string is being pulled out the memory probe moves with the string and records data quasi‐continuously. For the MARUM-MeBo70 we use since 2010 a spectrum gamma ray probe that records natural gamma ray intensity and analyses for potassium, uranium and thorium concentrations in the drilled formations. For the IODP Expedition 357 in 2015 ECORD funded two additional probes for measuring induction/resistivity and magnetic susceptibility. The latest development is a sonic tool for measuring p-wave velocities.

In addition to these bore hole logging tools a temperature probe and a Cone Penetration Testing (CPT) probe can be used for measuring in situ temperature and geotechnical characteristics within soft sediments.