Obtaining High‐Resolution Magnetic Records From Speleothems Using Magnetic Microscopy
Name
Geochem Geophys Geosyst - 2024 - Borlina - Obtaining High‐Resolution Magnetic Records From Speleothems Using Magnetic.pdf
Description
Published version
Size
2.59 MB
Format
Adobe PDF
Checksum (MD5)
a211ae143770c2f5d3e76ff3fd85cb20
Author(s)
Borlina, Cauê S
Lima, Eduardo A
Feinberg, Joshua M
Jaqueto, Plinio
Lascu, Ioan
Trindade, Ricardo IF
Font, Eric
Sánchez‐Moreno, Elisa M
Dimuccio, Luca Antonio
Yokoyama, Yusuke
Date Issued
October 5, 2024
Journal
Geochemistry, Geophysics, Geosystems
Publisher
American Geophysical Union
Citation
Borlina, C. S., Lima, E. A., Feinberg, J. M., Jaqueto, P., Lascu, I., Trindade, R. I. F., et al. (2024). Obtaining high-resolution magnetic records from speleothems using magnetic microscopy. Geochemistry, Geophysics, Geosystems, 25, e2024GC011594.
Version
Final published version
Abstract
Speleothems are mineral deposits capable of recording detrital and/or chemical remanent magnetization at annual timescales. They can offer high-resolution paleomagnetic records of short-term variations in Earth's magnetic field, crucial for understanding the evolution of the dynamo. Owing to limitations on the magnetic moment sensitivity of commercial cryogenic rock magnetometers (∼10−11 Am2), paleomagnetic studies of speleothems have been limited to samples with volumes of several hundreds of mm3, averaging tens to hundreds of years of magnetic variation. Nonetheless, smaller samples (∼1–10 mm3) can be measured using superconducting quantum interference device (SQUID) microscopy, with a sensitivity better than ∼10−15 Am2. To determine the application of SQUID microscopy for obtaining robust high-resolution records from small-volume speleothem samples, we analyzed three different stalagmites collected from Lapa dos Morcegos Cave (Portugal), Pau d'Alho Cave (Brazil), and Crevice Cave (United States). These stalagmites are representative of a range of magnetic properties and have been previously studied with conventional rock magnetometers. We show that by using SQUID microscopy we can achieve a five-fold improvement in temporal resolution for samples with higher abundances of magnetic carriers (e.g., Pau d'Alho Cave and Lapa dos Morcegos Cave). In contrast, speleothems with low abundances of magnetic carriers (e.g., Crevice Cave) do not benefit from higher resolution analysis and are best analyzed using conventional rock magnetometers. Overall, by targeting speleothem samples with high concentrations of magnetic carriers we can increase the temporal resolution of magnetic records, setting the stage for resolving geomagnetic variations at short time scales.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivatives
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DOI of Published Version
10.1029/2024gc011594
