Magnetic Imaging of the Effect of Stress on the Remanent Magnetization of Basalt

Abstract Differential compressional stresses (<100 MPa) that do not result in permanent deformation have traditionally been considered insufficient to modify paleomagnetic signals; however, recent numerical predictions have challenged this assumption. Using quantum diamond microscopy, we experimentally determined the effects of low differential stresses on the remanent magnetization of columnar basalt samples from Seljadalur, Iceland. We show that although individual magnetic dipoles rotate by up to 40°, the bulk magnetization direction remains largely unchanged. These rotations reflect opposing single‐domain–like and single‐vortex–like behaviors that cancel directionally; however, the bulk magnetization intensity decreases. This behavior is consistent with micromagnetic model predictions for mixed–domain‐state samples. Given that differential stresses 1 GPa are common in undeformed rocks distal to earthquake rupture zones and impact craters, it is essential to account for stress effects when interpreting paleomagnetic data from geological materials.