Understanding magnetic remanence acquisition in sediments through a combined experimental and numerical approach

• Applicant: Professor Dr. Stuart Alan Gilder
• Subject Area: Geophysics and Geodesy
• Term: from 2009 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 98959802

This is a renewal proposal for the project to better understand how sediments acquire a magnetic remanence. We have obtained unique spherical synthetic material whose size distribution and magnetic properties we have accurately characterized. We have systematically conducted several deposition experiments with this material showing that more than 80% of the remanence is acquired within ~100 minutes, the settling time of the largest grain size fraction, and is dependent on the applied field. We observe an appreciable inclination error, ascribed to the rolling of the particles in niches at the sediment-water interface, a mechanism that has been proposed but never directly observed. In our experiments the inclination error is dependent on the applied field and on the sediment concentration/sedimentation rate, which directly relates to the efficiency of locking-in of the particles. Due to the time it took to find the appropriate material and build the necessary experimental apparatus, we have only been acquiring publishable data since June 2010. Now that everything is in place and that the experiments are being performed uninterruptedly, we ask for only six months of additional funding which will allow us to finalize ongoing experiments on spherical particles, complete them with crucial additional experiments on ellipsoidal particles, and write up the results for publication.

• DFG Programme: Research Grants