Do meteorite impacts the geomagnetic field and can meteorites retain the record of planetary magnetic fields?

• Applicant: Professor Dr. Stuart Alan Gilder
• Co-Applicant: Professor Dr. Benjamin Paul Weiss
• Subject Area: Geophysics
• Term: from 2010 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 169945988

Meteorite impacts have profoundly influenced the evolution of planets in our solar system. The kinetic energy involved in impact events is released as a shock wave, with instantaneous pressures sometimes >100 GPa spread over hundreds of square kilometers. Seismic waves generated by the shock can potentially influence the geodynamo when reaching the Earth s core. Cessation of the Martian dynamo may have also been caused by a large meteorite impact. We propose to carry out detailed, systematic paleomagnetic studies of several terrestrial impact craters to test whether the geomagnetic field was perturbed by the impacts. If impact events strongly influenced the geodynamo, then the effects should be evident in the paleomagnetic data, either as swings in magnetic field direction or as fluctuations in intensity. We intend to track these changes in the cooling record of the rocks that were melted by the impact. We also will conduct studies on rocks shocked by the impacts in order to determine how their rock magnetic properties were modified and overprinted by the impact process. Moreover, we will conduct paleomagnetic studies of meteorites to constrain the intensities of early magnetic fields of the Moon, Mars, and planetesimals. The paleomagnetism of meteorites and impact craters are linked in that one of the key proposed field sources of the former is impact-generated plasmas on the parent body. It is critical to develop an understanding of the effects of shock waves on rock magnetic properties given that nearly all meteorite samples were shocked during ejectionfrom their parent bodies.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1488: Planetary Magnetism (PlanetMag)
• International Connection: USA
• Participating Person: Dr. Jean Pohl