Imperial College London

Dr. Adrian Muxworthy

Faculty of EngineeringDepartment of Earth Science & Engineering

Reader in Earth and Planetary Magnetism
 
 
 
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Contact

 

+44 (0)20 7594 6442adrian.muxworthy

 
 
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Location

 

4.48Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

291 results found

Conbhui PO, Williams W, Fabian K, Ridley P, Nagy L, Muxworthy ARet al., 2018, MERRILL: Micromagnetic Earth Related Robust Interpreted Language Laboratory, GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, Vol: 19, Pages: 1080-1106, ISSN: 1525-2027

JOURNAL ARTICLE

Evans ME, Muxworthy AR, 2018, A re-appraisal of the proposed rapid Matuyama-Brunhes geomagnetic reversal in the Sulmona Basin, Italy, GEOPHYSICAL JOURNAL INTERNATIONAL, Vol: 213, Pages: 1744-1750, ISSN: 0956-540X

JOURNAL ARTICLE

Harrison RJ, Muraszko J, Heslop D, Lascu I, Muxworthy AR, Roberts APet al., 2018, An Improved Algorithm for Unmixing First-Order Reversal Curve Diagrams Using Principal Component Analysis, Geochemistry, Geophysics, Geosystems, Vol: 19, Pages: 1595-1610

© 2018. American Geophysical Union. All Rights Reserved. First-order reversal curve (FORC) diagrams of synthetic binary mixtures with single-domain, vortex state, and multidomain end-members (EMs) were analyzed using principal component analysis (FORC-PCA). Mixing proportions derived from FORC-PCA are shown to deviate systematically from the known weight percent of EMs, which is caused by the lack of reversible magnetization contributions to the FORC distribution. The error in the mixing proportions can be corrected by applying PCA to the raw FORCs, rather than to the processed FORC diagram, thereby capturing both reversible and irreversible contributions to the signal. Here we develop a new practical implementation of the FORC-PCA method that enables quantitative unmixing to be performed routinely on suites of FORC diagrams with up to four distinct EMs. The method provides access not only to the processed FORC diagram of each EM, but also to reconstructed FORCs, which enables objective criteria to be defined that aid identification of physically realistic EMs. We illustrate FORC-PCA with examples of quantitative unmixing of magnetic components that will have widespread applicability in paleomagnetism and environmental magnetism.

JOURNAL ARTICLE

Roberts AP, Zhao X, Harrison RJ, Heslop D, Muxworthy AR, Rowan CJ, LarrasoaƱa J-C, Florindo Fet al., 2018, Signatures of Reductive Magnetic Mineral Diagenesis From Unmixing of First-Order Reversal Curves, Journal of Geophysical Research: Solid Earth, ISSN: 2169-9313

JOURNAL ARTICLE

Shah J, Williams W, Almeida TP, Nagy L, Muxworthy AR, Kovacs A, Valdez-Grijalva MA, Fabian K, Russell SS, Genge MJ, Dunin-Borkowski REet al., 2018, The oldest magnetic record in our solar system identified using nanometric imaging and numerical modeling, NATURE COMMUNICATIONS, Vol: 9, ISSN: 2041-1723

JOURNAL ARTICLE

Valdez-Grijalva MA, Nagy L, Muxworthy AR, Williams W, Fabian Ket al., 2018, The magnetic structure and palaeomagnetic recording fidelity of sub-micron greigite (Fe3S4), EARTH AND PLANETARY SCIENCE LETTERS, Vol: 483, Pages: 76-89, ISSN: 0012-821X

JOURNAL ARTICLE

Almeida TP, Muxworthy AR, Kovcas A, Williams W, Dunin-Borkowski REet al., 2017, Observation of thermally-induced magnetic relaxation in a magnetite grain using off-axis electron holography, ELECTRON MICROSCOPY AND ANALYSIS GROUP CONFERENCE 2017 (EMAG2017), Vol: 902, ISSN: 1742-6588

JOURNAL ARTICLE

Almeida TP, Muxworthy AR, Williams W, Dunin-Borkowski R, Kasama T, Hansen T, Kovacs A, Brown PD, Temple R, Massey J, Marrows C, McVitie Set al., 2017, Visualising dynamic chemical reactions and magnetic behaviour of nano-scale magnetic materials using electron microscopy (invited), Magnetic Interactions, Edinburgh

CONFERENCE PAPER

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

Berndt T, Ramalho RS, Valdez-Grijalva MA, Muxworthy ARet al., 2017, Paleomagnetic field reconstruction from mixtures of titanomagnetites, Magnetic Interactions, Edinburgh

CONFERENCE PAPER

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, Vol: 18, Pages: 3891-3903, ISSN: 1525-2027

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

JOURNAL ARTICLE

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, ...

BOOK CHAPTER

Muxworthy AR, 2017, Considerations for Latitudinal Time-Averaged-Field Palaeointensity Analysis of the Last Five Million Years, FRONTIERS IN EARTH SCIENCE, Vol: 5, 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

Paterson GA, Muxworthy AR, Yamamoto Y, Pan Yet al., 2017, Bulk magnetic domain stability controls paleointensity fidelity, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 114, Pages: 13120-13125, ISSN: 0027-8424

JOURNAL ARTICLE

Roberts AP, Almeida TP, Church NS, Harrison RJ, Heslop D, Li Y, Li J, Muxworthy AR, Williams W, Zhao Xet al., 2017, Resolving the Origin of Pseudo-Single Domain Magnetic Behavior, JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 122, Pages: 9534-9558, ISSN: 2169-9313

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

Shah J, Muxworthy AR, Almeida TP, Kovacs A, Russell SS, Genge M, Dunin-Borkowski Ret al., 2017, Dusty olivine: our oldest record of rock magnetism? (invited), Magnetic Interactions, Edinburgh

CONFERENCE PAPER

Valdez-Grijalva MA, Muxworthy AR, Williams W, Nagy Let al., 2017, The FORC function of non-interacting SD to PSD greigite ensembles, Magnetic Interactions, Edinburgh, 2017

CONFERENCE PAPER

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

JOURNAL ARTICLE

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

CONFERENCE PAPER

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

JOURNAL ARTICLE

Almeida TP, Muxworthy AR, Kovacs A, Williams W, Nagy L, Conbhui PO, Frandsen C, Supakulopas R, Dunin-Borkowski REet al., 2016, Direct observation of the thermal demagnetization of magnetic vortex structures in nonideal magnetite recorders, GEOPHYSICAL RESEARCH LETTERS, Vol: 43, Pages: 8426-8434, ISSN: 0094-8276

JOURNAL ARTICLE

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

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

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