Impact Demagnetization of Geological Materials

The understanding of demagnetization by hypervelocity impacts is crucial for the interpretation of magnetic anomalies on the Moon, Mars, and asteroids and of the paleomagnetic signal of rocks from these bodies. We propose an innovative approach to investigate the effects of impacts on the remanent magnetization of geologic materials. It consists of the combination of pulsed laserimpacts, room temperature SQUID microscopy and moment magnetometry measurements on millimeter samples. Laser impacts, besides being non-destructive, can reach several tens of GPa and allow well-calibrated modeling of shock wave propagation within the impacted samples. On the other hand, high-resolution SQUID microscopy allows mapping of the magnetic field with an unprecedented spatial resolution of about 100 m. Finally, magnetic measurements allow direct measurements of the magnetization that are necessary to perform the inversion of the magnetic field data and can give evidence for shock-modification of the intrinsic magnetic properties of the samples.