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  • Conference paper
    Williams W, Nagy L, Fabian K, Muxworthy ARet al., 2016,

    Evolution of magnetic domain structures from Pseudo-Single-Domain to Multidomain (poster)

    , EGU 2016
  • Journal article
    Almeida T, Muxworthy AR, Kovacs A, Williams W, Brown PD, Dunin-Borkowski REet al., 2016,

    Direct visualization of the thermomagnetic behaviour of pseudo-single-domain magnetite particles

    , Science Advances, Vol: 2, Pages: 1-5, ISSN: 2375-2548

    The study of the palaeomagnetic signal recorded by rocks allows scientists to understand the Earth’s past magnetic field and the formation of the geodynamo. The magnetic recording fidelity of this signal is dependent on the magnetic domain state it adopts. The most prevalent example found in nature is the pseudo-single-domain (PSD) structure, yet its recording fidelity is poorly understood. Here, the thermo-remanent behaviour of PSD magnetite (Fe3O4) particles, which dominate the magnetic signatures of many rock lithologies, is investigated using electron holography. This study provides spatially resolved magnetic information from individual Fe3O4 grains as a function of temperature, which has been previously inaccessible. A small exemplar Fe3O4 grain (~ 150 nm) exhibits dynamic movement of its magnetic vortex structure above 400˚C, recovering its original state upon cooling, whilst a larger exemplar Fe3O4 grain (~ 250 nm) is shown to retain its vortex state on heating to 550˚C, close to the Curie temperature of 580˚C. Hence, it is demonstrated that Fe3O4 grains containing vortex structures are indeed reliable recorders of palaeo-directional and -intensity information; and the presence of PSD magnetic signals does not preclude the successful recovery of palaeomagnetic signals.
  • Journal article
    Shah J, Koppers AP, Leitner M, Leonhardt R, Muxworthy AR, Heunemann C, Bachtadse V, Ashley JAD, Matzka Jet al., 2016,

    Palaeomagnetic evidence for the persistence or recurrence of geomagnetic main field anomalies in the South Atlantic

    , Earth and Planetary Science Letters, Vol: 441, Pages: 113-124, ISSN: 1385-013X

    We present a dataset of a full-vector palaeomagnetic study of Late Pleistocene lavas from the island Tristan da Cunha in the South Atlantic Ocean. The current day geomagnetic field intensity in this region is approximately 25 μT, compared to an expected value of ∼43 μT; this phenomenon is known as the South Atlantic geomagnetic Anomaly (SAA). Geomagnetic field models extending back to the last 10 ka find no evidence for this being a persistent feature of the geomagnetic field, albeit, all models are constructed from data which is particularly sparse in the southern hemisphere. New 40Ar/39Ar incremental heating dating indicates the studied lavas from Tristan da Cunha extruded between 90 and 46 ka. Palaeointensity estimations of eight lava flows made using the Thellier method yield an average palaeointensity of 18±6 μT and virtual axial dipole moment (VADM) of 3.1±1.2×1022 Am2. The lava flows demonstrate four time intervals comparable to the present day SAA, where the average VADM of the Tristan da Cunha lavas is weaker than the global VADM average. This suggests a persistent or recurring low intensity anomaly to the main geomagnetic field similar to the SAA existed in the South Atlantic between 46 and 90 ka.
  • Conference paper
    Shah J, Muxworthy AR, Almeida T, Kovacs A, Russell SS, Genge M, Dunin-Borkowski Ret al., 2016,

    Hot Holography: Magnetic recording fidelity of dusty olivine (poster)

    , 13th UK Planetary Forum Early Career Scientists’ Meeting
  • Journal article
    Berndt T, Muxworthy AR, Fabian K, 2016,

    Does size matter? Statistical limits of paleomagnetic field reconstruction from small rock specimens

    , Journal of Geophysical Research: Solid Earth, Vol: 121, Pages: 15-26, ISSN: 2169-9356

    As samples of ever decreasing sizes are being studied paleomagnetically, care has to be taken that the underlying assumptions of statistical thermodynamics (Maxwell-Boltzmann statistics) are being met. Here we determine how many grains and how large a magnetic moment a sample needs to have to be able to accurately record an ambient field. It is found that for samples with a thermoremanent magnetic moment larger than 10−11Am2 the assumption of a sufficiently large number of grains is usually given. Standard 25 mm diameter paleomagnetic samples usually contain enough magnetic grains such that statistical errors are negligible, but “single silicate crystal” works on, for example, zircon, plagioclase, and olivine crystals are approaching the limits of what is physically possible, leading to statistic errors in both the angular deviation and paleointensity that are comparable to other sources of error. The reliability of nanopaleomagnetic imaging techniques capable of resolving individual grains (used, for example, to study the cloudy zone in meteorites), however, is questionable due to the limited area of the material covered.
  • Conference paper
    Almeida TP, Muxworthy AR, Williams W, Kovacs A, Dunin-Borkowski Ret al., 2016,

    Direct visualization of CRM and TRM of pseudo-single-domain magnetite particles (invited)

    , Magnetic Interaction 2016
  • Conference paper
    Almeida T, Muxworthy AR, Kasama T, Williams W, Damsgaard C, Frandsen C, Pennycook T, Dunin-Borkowski Ret al., 2016,

    Effect of maghemization on the magnetic properties of non-stoichiometric pseudo-single-domain magnetite particles (poster)

    , Magnetic Interactions 2016
  • Conference paper
    Mac Niocaill C, Muxworthy AR, Vowles K, Wilkinson Jet al., 2016,

    Palaeomagnetic dates of Irish Zn-Pb deposits record regional remagnetization related to Variscan fluid flow

    , Magnetic Interactions 2016
  • Conference paper
    Abubakar R, Muxworthy AR, Sephton M, Fraser A, Watson J, Southern P, Heslop D, Paterson Get al., 2016,

    Mapping Petroleum Migration Pathways in Wessex Basin Using Magnetics and Seismic Mapping (poster)

    , Magnetic Interactions 2016
  • Conference paper
    Badejo, Muxworthy AR, Fraser A, 2016,

    Application of magnetic techniques to lateral hydrocarbon migration - Lower Tertiary reservoir systems, UK North Sea (poster)

    , Magnetic Interactions 2016
  • Conference paper
    Muxworthy AR, 2016,

    How Well Does Preisach Theory Predict Pseudo-Single-Domain Behavior? (poster)

    , Magnetic Interactions 2016
  • Conference paper
    Shah J, Muxworthy AR, Almeida TP, Kovacs A, Russell SS, Genge M, Dunin-Borkowski Ret al., 2016,

    In-situ heating holography of chondrule dusty olivine

    , Magnetic Interactions
  • Conference paper
    Maidment S, Muxworthy AR, 2016,

    A chronostratigraphic framework for the Morrison formation, western USA: A sequence stratigraphic and magnetostratigraphic approach (poster)

    , Magnetic Interactions 2016
  • Conference paper
    Valdez-Grijalva MA, Muxworthy AR, 2016,

    Simulated 'early onset' PSD behaviour: Size and shape effects in non-interacting greigite nanoparticles

    , Magnetic Interactions 2016
  • Conference paper
    Supakulopas R, Muxworthy AR, Døssing A, Riishuus MSet al., 2016,

    The palaeomagnetic field properties at high northern latitudes: preliminary results from Eyjafjardardalur valley

    , Magnetic Interactions 2016

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

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