An exceptionally weak Devonian geomagnetic field recorded by the Viluy Traps, Siberia



Hawkins, LMA, Anwar, T, Shcherbakova, VV, Biggin, AJ ORCID: 0000-0003-4164-5924, Kravchinsky, VA, Shatsillo, AV and Pavlov, VE
(2019) An exceptionally weak Devonian geomagnetic field recorded by the Viluy Traps, Siberia. EARTH AND PLANETARY SCIENCE LETTERS, 506. 134 - 145.

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Abstract

The detection of anomalous time averaged geomagnetic behaviour is crucial for understanding past magnetospheric shielding and inferring deep Earth evolution. Links have been suggested between geomagnetic field variation over timescales of tens to hundreds of millions of years and processes near the core–mantle boundary (CMB); however, this becomes difficult to establish prior to the Permo-Carboniferous Reversed Superchron (PCRS; 267–319 Ma) due to a lack of reliable data. To improve the record prior to the PCRS, we present multi-method produced paleointensity results from nines dykes and lava flows from the Viluy Traps, Siberia, emplaced during the Upper Devonian between 376.7 ± 1.7 Ma and 364.4 ± 1.7 Ma. These sites have previously been published as part of two paleodirectional studies, one of which produced the accepted 360 Ma pole for Siberia (Q factor 6). All of the sites produced very weak field values ranging from 4.3–14.9 Z A m2, in close agreement with other recent results from Mid-Lower Devonian Siberian samples. QPI criteria have been used to illustrate the reliability of these new, low paleointensities, confirming the period of weak field suggested by other recent Siberian work, and the period of implied increased incidence of solar wind radiation, extended into the Upper Devonian. Along with evidence for moderate-high reversal frequencies and a potentially significant multipolar component during the Devonian, these weak field values also suggest a significantly different pattern of heat flow across the CMB relative to more recent times.

Item Type: Article
Uncontrolled Keywords: paleomagnetism, paleointensity, geomagnetic reversals, GAD, Devonian, Viluy Traps
Depositing User: Symplectic Admin
Date Deposited: 28 Nov 2018 08:52
Last Modified: 09 Jan 2021 04:35
DOI: 10.1016/j.epsl.2018.10.035
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3029136