Publication
Micromagnetic Tomography for Paleomagnetism and Rock‐Magnetism
Publisher:
American Geophysical Union (AGU)
Date:
10-2021
DOI:
10.1029/2021JB022364
Abstract: Our understanding of the past behavior of the geomagnetic field arises from magnetic signals stored in geological materials, e.g., (volcanic) rocks. Bulk rock s les, however, often contain magnetic grains that differ in chemistry, size, and shape some of them record the Earth's magnetic field well, others are unreliable. The presence of a small amount of adverse behaved magnetic grains in a s le may already obscure important information on the past state of the geomagnetic field. Recently it was shown that it is possible to determine magnetizations of in idual grains in a s le by combining X‐ray computed tomography and magnetic surface scanning measurements. Here we establish this new Micromagnetic Tomography (MMT) technique and make it suitable for use with different magnetic scanning techniques, and for both synthetic and natural s les. We acquired reliable magnetic directions by selecting subsets of grains in a synthetic s le, and we obtained rock‐magnetic information of in idual grains in a volcanic s le. This illustrates that MMT opens up entirely new venues of paleomagnetic and rock‐magnetic research. MMT's unique ability to determine the magnetization of in idual grains in a nondestructive way allows for a systematic analysis of how geological materials record and retain information on the past state of the Earth's magnetic field. Moreover, by interpreting only the contributions of known magnetically well‐behaved grains in a s le, MMT has the potential to unlock paleomagnetic information from even the most complex, crucial, or valuable recorders that current methods are unable to recover.