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  • JOURNAL ARTICLE
    Almeida TP, Muxworthy AR, Kovacs A, Williams W, Dunin-Borkowski REet al., 2017,

    Observation of thermally-induced magnetic relaxation in a magnetite grain using off-axis electron holography

    , Journal of Physics : Conference Series, Vol: 902, ISSN: 1742-6588

    A synthetic basalt comprising magnetic Fe3O4 grains (~ 50 nm to ~ 500 nm in diameter) is investigated using a range of complementary nano-characterisation techniques. Off-axis electron holography combined with in situ heating allowed for the visualisation of the thermally-induced magnetic relaxation of an Fe3O4 grain (~ 300 nm) from an irregular domain state into a vortex state at 550˚C, just below its Curie temperature, with the magnetic intensity of the vortex increasing on cooling.

  • JOURNAL ARTICLE
    Berndt T, Muxworthy AR, 2017,

    Dating Icelandic glacial floods using a new viscous remanent magnetization protocol

    , GEOLOGY, Vol: 45, Pages: 339-342, ISSN: 0091-7613
  • JOURNAL ARTICLE
    Berndt T, Paterson GA, Cao C, Muxworthy ARet al., 2017,

    Experimental test of the heating and cooling rate effect on blocking temperatures

    , GEOPHYSICAL JOURNAL INTERNATIONAL, Vol: 210, Pages: 255-269, ISSN: 0956-540X
  • JOURNAL ARTICLE
    Berndt T, Ramalho RS, Valdez-Grijalva MA, Muxworthy ARet al., 2017,

    Paleomagnetic field reconstruction from mixtures of titanomagnetites

    , Earth and Planetary Science Letters, Vol: 465, Pages: 70-81, ISSN: 0012-821X

    Stepwise thermal demagnetization and alternating field (AF) demagnetization are commonly used in paleomagnetic studies to isolate remanent magnetic components of different origins. The magnetically hardest, i.e. highest unblocking temperature/peak field component is often interpreted as the primary magnetization and magnetically softer components as subsequent remagnetizations due to geological events posterior to the formation of the rock, such as reheating or formation of new magnetic minerals. The correct interpretation of the sequence of the geological events such as tectonic rotations from paleomagnetic data often relies on correctly attributing the observed magnetic directions to the remanence carriers and acquisition mechanisms. Using a numerical model to simulate remanence acquisition and stepwise thermal and AF demagnetization experiments, we show that the presence of mixtures of different magnetic minerals, such as magnetite and titanomagnetites of varying titanium-content can have very significant effects on Zijderveld plots. In thermal demagnetization experiments a spurious third component at intermediate temperatures or a continuous curvature may arise from an overlap of the primary remanence with a subsequent thermal or viscous remagnetization carried by small-grained iron-rich magnetite and large-grained titanium-rich titanomagnetite. AF demagnetization plots of magnetic mixtures are even more complex: primary and secondary remanences carried by different minerals may appear as either three or four components in Zijderveld plots. During alternating field demagnetization the highest coercivity component is not necessarily equivalent to the primary remanence and does not necessarily correspond to the highest temperature component in an analogous thermal demagnetization experiment, i.e., the primary remanence direction cannot be recovered. The effects are shown to be due to the different responsiveness of magnetite and titanomagnetites towards viscous or

  • JOURNAL ARTICLE
    Di Chiara A, Muxworthy AR, Trindade RIF, Bispo-Santos Fet al., 2017,

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

    , Geochemistry, Geophysics, Geosystems, ISSN: 1525-2027

    A recent hypothesis has suggested that Earth's inner core nucleated during the Mesoproterozoic, as evidenced by a rapid increase in the paleointensity (ancient geomagnetic field intensity) record; however, paleointensity data during the Paleoproterozoic and Mesoproterozoic period are limited. To address this problem, we have determined paleointensity from samples from three Paleoproterozoic Avanavero mafic sills (Amazonian Craton, Brazil): Cotingo, 1782 Ma, Puiuà 1788, and Pedra Preta, 1795 Ma. We adopted a multi-protocol approach for paleointensity estimates combining Thellier-type IZZI and LTD-IZZI methods, and the non-heating Preisach protocol. We obtained an average VDM value of 1.3 ± 0.7 × 1022Am2 (Cotingo) of 2.0 ± 0.4 × 1022Am2 (Puiuà) and 6 ± 4 × 1022Am2 (Pedra Preta); it is argued that the Cotingo estimate is the most robust. Our results are the first data from the upper Paleoproterozoic for South America and are comparable to data available from other regions and similar periods. The new data do not invalidate the hypothesis of that Earth's inner core nucleated during the Mesoproterozoic.

  • JOURNAL ARTICLE
    Hofman J, Maher BA, Muxworthy AR, Wuyts K, Castanheiro A, Samson Ret al., 2017,

    Biomagnetic Monitoring of Atmospheric Pollution: A Review of Magnetic Signatures from Biological Sensors

    , ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 51, Pages: 6648-6664, ISSN: 0013-936X
  • BOOK CHAPTER
    Maidment S, Balikova D, Muxworthy AR, 2017,

    Magnetostratigraphy of the Morrison Formation, Utah

    , Terrestrial Depositional Systems Deciphering Complexities Through Multiple Stratigraphic Methods, Editors: Zeigler, Parker, Publisher: Elsevier, ISBN: 9780128032435

    Terrestrial Depositional Systems: Deciphering Complexities through Multiple Stratigraphic Methods is the first collection of contributed articles that not only introduces young geoscientists to biostratigraphy, chemostratigraphy, ...

  • JOURNAL ARTICLE
    Muxworthy AR, 2017,

    Considerations for latitudinal time-averaged-field palaeointensity analysis of the last five million years

    , Frontiers in Earth Science, ISSN: 2296-6463
  • JOURNAL ARTICLE
    Muxworthy AR, Bland PA, Davison TM, Moore J, Collins GS, Ciesla FJet al., 2017,

    Evidence for an impact-induced magnetic fabric in Allende, and exogenous alternatives to the core dynamo theory for Allende magnetization

    , METEORITICS & PLANETARY SCIENCE, Vol: 52, Pages: 2132-2146, ISSN: 1086-9379
  • JOURNAL ARTICLE
    Nagy L, Williams W, Muxworthy AR, Fabian K, Almeida TP, Conbhui PO, Shcherbakov VPet al., 2017,

    Stability of equidimensional pseudo-single-domain magnetite over billion-year timescales

    , PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 114, Pages: 10356-10360, ISSN: 0027-8424
  • JOURNAL ARTICLE
    Shah J, Bates HC, Muxworthy AR, Hezel DC, Russell SS, Genge MJet al., 2017,

    Long-lived magnetism on chondrite parent bodies

    , EARTH AND PLANETARY SCIENCE LETTERS, Vol: 475, Pages: 106-118, ISSN: 0012-821X
  • JOURNAL ARTICLE
    Wilkinson JJ, Vowles K, Muxworthy AR, Mac Niocaill Cet al., 2017,

    Regional remagnetization of Irish Carboniferous carbonates dates Variscan orogenesis, not Zn-Pb mineralization

    , GEOLOGY, Vol: 45, Pages: 747-750, ISSN: 0091-7613
  • 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
    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
  • JOURNAL ARTICLE
    Almeida TP, Muxworthy AR, Kovacs A, Williams W, Brown PD, Dunin-Borkowski REet al., 2016,

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

    , SCIENCE ADVANCES, Vol: 2, ISSN: 2375-2548

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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