ORCID Profile
0000-0001-9210-7574
Current Organisation
The University of Edinburgh
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Publisher: Oxford University Press (OUP)
Date: 15-07-2004
Publisher: Elsevier BV
Date: 11-2022
Publisher: American Geophysical Union (AGU)
Date: 12-2017
DOI: 10.1002/2017JB014860
Publisher: American Geophysical Union (AGU)
Date: 2021
DOI: 10.1029/2020GC009423
Abstract: The theory for recording of thermally blocked remanences predicts a quasilinear relationship between low fields like the Earth's in which rocks cool and acquire a magnetization. This serves as the foundation for estimating ancient magnetic field strengths. Addressing long‐standing questions concerning Earth's magnetic field requires a global paleointensity data set, but recovering the ancient field strength is complicated because the theory only pertains to uniformly magnetized particles. A key requirement of a paleointensity experiment is that a magnetization blocked at a given temperature should be unblocked by zero‐field reheating to the same temperature. However, failure of this requirement occurs frequently and the causes and consequences of failure are understood incompletely. Recent experiments demonstrate that the remanence in many s les typical of those used in paleointensity experiments is unstable, exhibiting an “aging” effect in which the (un)blocking temperature spectra can change over only a few years resulting in nonideal experimental behavior. While a fresh remanence may conform to the requirement of equality of blocking and unblocking temperatures, aged remanences may not. Blocking temperature spectra can be unstable (fragile), which precludes reproduction of the conditions under which the original magnetization was acquired. This limits our ability to acquire accurate and precise ancient magnetic field strength estimates because differences between known and estimated fields can be significant for in idual specimens, with a low field bias. Fragility of unblocking temperature spectra may be related to grain sizes with lower energy barriers and may be detected by features observed in first‐order reversal curves.
Publisher: Elsevier BV
Date: 10-2012
Publisher: American Geophysical Union (AGU)
Date: 17-02-2009
DOI: 10.1029/2008JB006017
Publisher: Proceedings of the National Academy of Sciences
Date: 31-12-2018
Abstract: The Earth’s geodynamo is critical in protecting our atmosphere, and thus plays an important role in the habitability of our planet. As such, the Earth’s magnetic field has likely played a crucial role in the emergence of life around 4 billion years ago during the Hadean–Archean Eons. However, we know little about the behavior of the geodynamo during this critical period. Recent efforts have focused on the magnetic signals harbored by Jack Hills zircon crystals, the oldest terrestrial material. Here we show the magnetic carriers in such grains. Our results demonstrate that although ancient zircon grains may contain ideal magnetic recorders, they do not record the magnetic field strength at the time of zircon growth.
Publisher: American Geophysical Union (AGU)
Date: 12-2013
DOI: 10.1002/2013GC004973
Publisher: Wiley
Date: 22-11-2020
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Wyn Williams.