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- Title
Unraveling the Magnetic Signal of Individual Grains in a Hawaiian Lava Using Micromagnetic Tomography.
- Authors
Kosters, Martha E.; de Boer, Rosa A.; Out, Frenk; Cortés‐Ortuño, David I.; de Groot, Lennart V.
- Abstract
Micromagnetic Tomography (MMT) is a new technique that allows the determination of magnetic moments of individual grains in volcanic rocks. Current MMT studies either showed that it is possible to obtain magnetic moments of relatively small numbers of grains in ideal sample material or provided important theoretical advances in MMT inversion theory and/or its statistical framework. Here, we present a large‐scale application of MMT on a sample from the 1907‐flow from Hawaii's Kilauea volcano producing magnetic moments of 1,646 grains. We produced 261,305 magnetic moments in total for these 1,646 grains, an increase of three orders of magnitude compared to earlier studies to assess the robustness of the MMT results, and a major step toward the number of grains that is necessary for paleomagnetic applications of MMT. Furthermore, we show that the recently proposed signal strength ratio is a powerful tool to scrutinize and select MMT results. Despite this progress, still only relatively large iron‐oxide grains with diameters >1.5–2 μm can be reliably resolved, impeding a reliable paleomagnetic interpretation. To determine the magnetic moments of smaller (<1 μm) grains that may exhibit pseudo‐single domain behavior and are therefore better paleomagnetic recorders, the resolution of the microcomputed tomography and magnetic scans necessary for MMT must be improved. Therefore, it is necessary to reduce the sample size in future MMT studies. Nevertheless, our study is an important step toward making MMT a useful paleomagnetic and rock‐magnetic technique. Plain Language Summary: The magnetic information of volcanic rocks is an invaluable archive of the behavior of the Earth's magnetic field through time. Recently, a new technique, Micromagnetic Tomography, was proposed that promises to determine the magnetic signals of individual iron‐bearing grains in these rocks. This would greatly improve our ability to obtain and interpret the magnetic information stored in them. Here, we go beyond the proof‐of‐concept of this exciting new technique and show that it is indeed possible to obtain statistically robust results for a set of rather large grains, with diameters >1.5–2 μm, in a sample from the 1907‐flow from Hawaii's Kilauea volcano. Key Points: We studied a sample from the 1907‐flow of Kilauea (Hawaii) with well‐known rock‐magnetic properties using Micromagnetic Tomography (MMT)We performed 16,874 MMT inversions to characterize the magnetic moments of 1,646 grains, resulting in 261,305 magnetic momentsMagnetic moments were found only for grains >1.5–2 μm that exhibit multidomain behavior, but these MMT results are statistically robust
- Subjects
KILAUEA Volcano (Hawaii); GEOMAGNETISM; TOMOGRAPHY; MAGNETIC moments; GRAIN; VOLCANIC ash, tuff, etc.; TRANSCRANIAL magnetic stimulation; LAVA
- Publication
Geochemistry, Geophysics, Geosystems: G3, 2023, Vol 24, Issue 4, p1
- ISSN
1525-2027
- Publication type
Article
- DOI
10.1029/2022GC010462