Fu, R. R. et al. (2017) Evaluating the paleomagnetic potential of single zircon crystals using the Bishop Tuff. Earth and Planetary Science Letters, 458, pp. 1-13. (doi: 10.1016/j.epsl.2016.09.038)
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Abstract
Zircon crystals offer a unique combination of suitability for high-precision radiometric dating and high resistance to alteration. Paleomagnetic experiments on ancient zircons may potentially constrain the history of the earliest geodynamo, which would hold broad implications for the early Earth's interior and atmosphere. However, the ability of zircons to record accurately the geomagnetic field has not been demonstrated. Here we conduct thermal and alternating field (AF) paleointensity experiments on 767.1 thousand year old (ka) zircons from the Bishop Tuff, California. The rapid emplacement of these zircons in a well-characterized magnetic field provides a high-fidelity test of the zircons' intrinsic paleomagnetic recording accuracy. Successful dual heating experiments on eleven zircons measured using a superconducting quantum interference device (SQUID) microscope yield a mean paleointensity of (1σ; after excluding possible maghemite-bearing zircons), which is consistent with high-precision results from Bishop Tuff whole rock (). High-resolution quantum diamond magnetic (QDM) mapping, electron microscopy, and X-ray tomography indicate that the bulk of the remanent magnetization in Bishop Tuff zircons is carried by Fe oxides associated with apatite inclusions, which may be susceptible to destruction via metamorphism and aqueous alteration in older zircons. As such, while zircons can reliably record the geomagnetic field, robust zircon-derived paleomagnetic results require careful characterization of the ferromagnetic carrier and demonstration of their occurrence in primary inclusions. We further conclude that a combination of quantum diamond magnetometry and high-resolution imaging can provide detailed, direct characterization of the ferromagnetic mineralogy of geological samples.
| Item Type: | Articles |
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| Additional Information: | RRF is supported by the Lamont-Doherty Post-Doctoral Fellowship. BPW, EAL, and JFDFA acknowledge support from NSF grant DMS-1521765. PK acknowledges support from the IC Postdoctoral Research Fellowship Program. DRG and RLW acknowledge support from the DARPA QuASAR HR0011-11-C-0073 and NSF EPMD 1408075 programs. JFE and RJH acknowledge funding under ERC Advance grant 320750—Nanopaleomagnetism. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Einsle, Dr Joshua Franz |
| Authors: | Fu, R. R., Weiss, B. P., Lima, E. A., Kehayias, P., Araujo, J. F.D.F., Glenn, D. R., Gelb, J., Einsle, J. F., Bauer, A. M., Harrison, R. J., Ali, G. A.H., and Walsworth, R. L. |
| College/School: | College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences |
| Journal Name: | Earth and Planetary Science Letters |
| Publisher: | Elsevier |
| ISSN: | 0012-821X |
| ISSN (Online): | 1385-013X |
| Published Online: | 02 November 2016 |
| Copyright Holders: | Copyright © 2016 Elsevier |
| First Published: | First published in Earth and Planetary Science Letters 458:1-13 |
| Publisher Policy: | Reproduced in accordance with the copyright policy of the publisher |
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