Paleoproterozoic Geomagnetic Field Strength From the Avanavero Mafic Sills, Amazonian Craton, Brazil

Chiara, Anita Di; Muxworthy, Adrian R.; Trindade, R. I.; Bispo-Santos, Franklin

doi:10.1002/2017gc007175

Cited by 13 publications

(2 citation statements)

References 56 publications

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“…We model gCRM acquisition for specific magnetic assemblages using synthetic Preisach distributions, which are normally distributed in both h c and h s . These can be easily replaced by experimentally measured first‐order‐reversal‐curve (FORC) distributions (e.g., Di Chiara et al., 2017; Muxworthy et al., 2011; Muxworthy et al., 2017) because Preisach and FORC distributions are both plots of h c and h s , but FORC diagrams are experimentally derived and not usually symmetrical. The Preisach distributions are populated with a number of hysterons, for example, 5 × 10 5 , each assigned a h c and h s value, where

{h}_{c}={H}_{c}\sqrt{2}

(Muxworthy & Heslop, 2011).…”

Section: Modeling Crm Acquisition Of Synthetic Distributionsmentioning

confidence: 99%

Using Preisach Theory to Evaluate Chemical Remanent Magnetization and Its Behavior During Thellier‐Thellier‐Coe Paleointensity Experiments

Baker

Muxworthy

2023

JGR Solid Earth

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Magnetic minerals within rocks, meteorites and sediments can record the ambient magnetic field during their formation, acquiring remanent magnetizations. There are several recording mechanisms depending on the rock type and mineral formation. For example, a thermoremanent magnetization (TRM) is acquired during cooling from above the constituent minerals' Curie temperatures, and chemical remanent magnetizations (CRM) are acquired if a mineral forms or alters below its Curie temperature. The recording mechanisms of these various remamances differs. Whilst much attention has historically been given to TRM acquisition (e.g.,

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{h}_{c}={H}_{c}\sqrt{2}

(Muxworthy & Heslop, 2011).…”

Section: Modeling Crm Acquisition Of Synthetic Distributionsmentioning

confidence: 99%

Using Preisach Theory to Evaluate Chemical Remanent Magnetization and Its Behavior During Thellier‐Thellier‐Coe Paleointensity Experiments

Baker

Muxworthy

2023

JGR Solid Earth

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“…Tarduno et al 2015;Herrero-Bervera et al 2016;Tarduno et al 2020), Proterozoic (e.g. Kulakov et al 2013;Di Chiara et al 2017;Sprain et al 2018;Kodama et al 2019) andPalaeozoic (e.g. Usui &Tian 2017;Hawkins et al 2019;Veselovskiy et al 2019).…”

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confidence: 99%

Dynamo constraints on the long-term evolution of Earth’s magnetic field strength

Davies

Bono

Meduri

et al. 2021

Geophysical Journal International

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SUMMARY Elucidating the processes in the liquid core that have produced observed palaeointensity changes over the last 3.5 Gyr is crucial for understanding the dynamics and long-term evolution of Earth’s deep interior. We combine numerical geodynamo simulations with theoretical scaling laws to investigate the variation of Earth’s magnetic field strength over geological time. Our approach follows the study of Aubert et al., adapted to include recent advances in numerical simulations, mineral physics and palaeomagnetism. We first compare the field strength within the dynamo region and on the core–mantle boundary (CMB) between a suite of 314 dynamo simulations and two power-based theoretical scaling laws. The scaling laws are both based on a Quasi-Geostropic (QG) force balance at leading order and a Magnetic, Archimedian, and Coriolis (MAC) balance at first order and differ in treating the characteristic length scale of the convection as fixed (QG-MAC-fixed) or determined as part of the solution (QG-MAC-free). When the data set is filtered to retain only simulations with magnetic to kinetic energy ratios greater than at least two we find that the internal field together with the root-mean-square and dipole CMB fields exhibit power-law behaviour that is compatible with both scalings within uncertainties arising from different heating modes and boundary conditions. However, while the extrapolated intensity based on the QG-MAC-free scaling matches Earth’s modern CMB field, the QG-MAC-fixed prediction shoots too high and also significantly overestimates palaeointensities over the last 3.5 Gyr. We combine the QG-MAC-free scaling with outputs from 275 realizations of core–mantle thermal evolution to construct synthetic true dipole moment (TDM) curves spanning the last 3.5 Gyr. Best-fitting TDMs reproduce binned PINT data during the Bruhnes and before inner core nucleation (ICN) within observational uncertainties, but PINT does not contain the predicted strong increase and subsequent high TDMs during the early stages of inner core growth. The best-fitting models are obtained for a present-day CMB heat flow of 11–16 TW, increasing to 17–22 TW at 4 Ga, and predict a minimum TDM at ICN.

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Palaeomagnetic Field Intensity

Biggin¹,

Paterson²,

Suttie³

et al. 2020

Encyclopedia of Solid Earth Geophysics

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Paleoproterozoic Geomagnetic Field Strength From the Avanavero Mafic Sills, Amazonian Craton, Brazil

Cited by 13 publications

References 56 publications

Using Preisach Theory to Evaluate Chemical Remanent Magnetization and Its Behavior During Thellier‐Thellier‐Coe Paleointensity Experiments

Using Preisach Theory to Evaluate Chemical Remanent Magnetization and Its Behavior During Thellier‐Thellier‐Coe Paleointensity Experiments

Dynamo constraints on the long-term evolution of Earth’s magnetic field strength

Palaeomagnetic Field Intensity

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