Reconstructing the full vector paleomagnetic field information from dated volcanic glass and correcting for cooling rate effects

• Applicant: Dr. Roman Leonhardt
• Subject Area: Geophysics
• Term: from 2007 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 34240892

Reliable paleomagnetic data, giving information about both direction and intensity of the Earth’s magnetic field, is crucial to understand the evolution of this field throughout the geological past. It is suggested that volcanic glass is an ideal material for such paleomagnetic records, because all biasing effects which are usually hard or impossible to detect in other recording media, are either absent or can be corrected for by using mineralogical and rock magnetic constraints. Volcanic glass is often pristine and contains a magnetic fraction in the single domain range. In collaboration with volcanologists the structural properties of volcanic glass, particularly the glass transition and the natural cooling rate across this transition are investigated by relaxation geospeedometry. Determination of cooling rate dependency of the thermoremanence allows for an extrapolation to natural cooling rates and, thus, a correction of absolute paleointensity determinations conducted on laboratory time scales. It is proposed to investigate a collection of glass yielding different age, composition, facies and quenching environment. In dependency of these conditions, the ideal character of volcanic glass regarding paleomagnetic research will be verified. The obtained paleomagnetic records will be used to reconstruct the past global geomagnetic field evolution and to improve analyzes techniques, in particular, paleointensity determination.

• DFG Programme: Research Grants