3D Joint Inversion of Scanning Magnetic Microscopy Data

Scanning magnetic microscopy (SMM) is a modern magnetometry technique that maps the magnetic anomalies resulting from small-scale variations of remanent magnetization within a sample. This information is vital to understand the origin of rock behavior in laboratory experiments and in larger scale magnetic surveys. To quantify the fine-scale remanent magnetization, we used 3D magnetic vector inversion to jointly invert SMM data collected both above and below a 5 mm-thick norite sample from the Bjerkreim-Sokndal layered intrusion in South Norway. The sample is from an area with a striking remanent aeromagnetic anomaly which shows a minimum of -13,000 nT below background in the high-resolution helicopter survey. Inversion results confirm bulk remanent magnetization measurements with calculated median magnetization intensities between 79 and 106 A/m and a strong preferred magnetization direction perpendicular to the slab plane. Furthermore, results indicate that the main source of natural remanent magnetization is in the pyroxenes.