Replication Data for: Microscale magnetic inversion of remanent magnetization mineral sources from the Black Hill Norite, South Australia.

Specimen BH01A is a 30um thick thin section from a core originally collected by Rajagopalan et al. (1993) from the northeast area of the Black Hill Norite pluton, South Australia. The distribution of opaque minerals in thin section were mapped using a Phenom XL scanning electron microscope (SEM) at the NTNU Rock Magnetic Laboratory. An electron backscatter (EBS) image was made of the entire thin section to broadly map the sample minerals distribution. The sample contains millimeter- to micron-sized grains. The ilmenite is present with, and without, reduction-exsolution lamellae of magnetite, where the lamellae vary in length from 3 to 50 µm. Pyroxene and plagioclase are the dominant silicates in the sample. The same thin section of specimen BH01A was scanned using NTNU’s Scanning Magnetic Microscope (Church & McEnroe, 2018). For mapping, the sample was placed in a Helmholtz coil to cancel out the local ambient magnetic field. The SMM only measures the vertical component of the magnetic field (Bz) in nT. Because mapping is conducted in a near free field environment, the SMM ultimately maps the sample’s magnetic remanence. Measurements were collected at 50 μm increments in both the x and y directions. The SMM experiences minor hardware noise, where vertical and horizontal striping occurred, with an average amplitude of 229nT. Considering the average amplitude of the anomalies is 1827nT, the dataset has a signal to noise ratio (SNR) of 18, which is sufficient for this analysis. References: Church, N. S., & McEnroe, S. A. (2018). Magnetic Field Surveys of Thin Sections. ASEG Extended Abstracts, (pp. 1-5) Rajagoplan, S., Schmidt, P., & Clark, P. (1993). Rock magnetism and geophysical interpretation of the Black Hill Norite, South Australia. Exploration Geophysics, 24, 209-212.