Article
Geochemistry & Geophysics
Frenk Out, David Cortes-Ortuno, Karl Fabian, Tristan van Leeuwen, Lennart de Groot
Summary: The Micromagnetic Tomography (MMT) technique, which combines high resolution scanning magnetometry and micro X-ray computed tomography, allows for the precise recovery of magnetic moments of individual magnetic grains in a sample. This study investigates the mathematical validity of MMT solutions by examining five factors: grain concentration, sample thickness, sample surface size, noise level in the magnetic scan, and sampling interval of the magnetic scan. Through numerical models, the influence of these parameters on the accuracy of the magnetizations of the grains is assessed. The authors also introduce a statistical uncertainty ratio and signal strength ratio to determine the most accurate solutions.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)
Article
Geochemistry & Geophysics
David Cortes-Ortuno, Karl Fabian, Lennart V. de Groot
Summary: Micromagnetic tomography aims to reconstruct individual magnetizations of magnetic particles by combining high-resolution magnetic scanning techniques with micro X-ray computed tomography. A mathematical procedure is described to recover higher orders of the magnetic potential of individual magnetic particles, allowing for detailed rock magnetic studies on large ensembles of particles. This approach provides valuable information about the stability and reliability of the particles as paleomagnetic remanence carriers.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2021)
Article
Geochemistry & Geophysics
Yuqin Wang, Kunpeng Ge, Wyn Williams, Hui Zhou, Huapei Wang, Lesleis Nagy, Lisa Tauxe, Jiang Wang, Shengbo Liu, Yang Liu
Summary: Recent research indicates that particles in the transitional zone between the single domain and single vortex regions are susceptible to thermal and external magnetic field instabilities, potentially impacting the accuracy of paleomagnetic interpretations. This study simulates the magnetic behavior of specific-shaped magnetite particles to evaluate their internal magnetization characteristics and influence on paleomagnetic observations. The findings reveal the size and dominant features of the magnetically unstable zone, highlighting their significance in paleomagnetic records.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Yo-ichiro Otofuji, Makoto Fujihara, Koji Uno
Summary: This study examines the paleomagnetic properties of serpentine in the Paleozoic Oeyama ophiolite in Southwest Japan, revealing reversed polarity magnetizations and different directions based on the temperature range. The rock magnetism analysis suggests that the magnetite grains play a crucial role in recording the geomagnetic field information during serpentinization.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geochemistry & Geophysics
David Cortes-Ortuno, Karl Fabian, Lennart V. de Groot
Summary: Micromagnetic tomography is a technique that combines X-ray micro computed tomography and scanning magnetometry data to obtain information about the magnetic potential of individual grains embedded in a sample. It has the capability to uniquely determine the magnetic potential of individual particles by numerical inversion of surface magnetic measurements. This technique is important for studying the ancient geomagnetic field and identifying stable paleomagnetic recorders in natural samples.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Lennart Groot, Karl Fabian, Annemarieke Beguin, Martha E. Kosters, David Cortes-Ortuno, Roger R. Fu, Chloe M. L. Jansen, Richard J. Harrison, Tristan Leeuwen, Auke Barnhoorn
Summary: The combination of X-ray computed tomography and magnetic surface scanning measurements allows for the determination of magnetizations of individual grains in a sample. The new Micromagnetic Tomography (MMT) technique opens up new avenues for paleomagnetic and rock-magnetic research by systematically analyzing how geological materials record and retain information on the past state of the Earth's magnetic field in a nondestructive way. MMT has the potential to unlock paleomagnetic information from even the most complex, crucial, or valuable recorders that current methods are unable to recover by interpreting only the contributions of known magnetically well-behaved grains in a sample.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geosciences, Multidisciplinary
Venkateshwarlu Mamilla, Ramesh Babu Nathi
Summary: A study using Paleomagnetism and rock magnetism as a proxy on dykes in India reveals two types of thermo-magnetic curves for Belagumba and Navile dykes, with magnetite as a remanence carrier. The magnetic directions of the dykes show two components and the corresponding paleopoles suggest a rapid drift rate and clockwise rotation during a specific time period.
JOURNAL OF ASIAN EARTH SCIENCES
(2023)
Article
Geochemistry & Geophysics
Kunpeng Ge, Wyn Williams, Lesleis Nagy, Lisa Tauxe
Summary: Recent micromagnetic simulations have predicted an abnormal region of low magnetic stability for particles with grain sizes near the domain state transitions, which could contribute to observational uncertainties in paleomagnetic recordings. By using low temperature oxidation of magnetite, researchers have been able to reevaluate the magnetic properties of particles close to this unstable zone, showing improved agreement with experimental data. The observed changes in remanence and coercivity near the proposed magnetic unstable zone provide the first experimental indication of its existence.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2021)
Article
Physics, Condensed Matter
Peng Shen, Dong Zhou, Shuai Liu, Chao Wang, Yingjian Guo, Lele Zhang, Yaping Wu, Rui Han, Yikun Fang, Minggang Zhu, Wei Li
Summary: The study examines the detailed rotation process of individual magnetic moment in a changing magnetic field, revealing a complex relationship between the direction of the magnetic moment and the anisotropy axis and magnetic field directions.
PHYSICA B-CONDENSED MATTER
(2022)
Article
Materials Science, Multidisciplinary
Jefferson F. D. F. Araujo, Andre L. A. Reis, Elder Yokoyama, Christian D. Medina, G. Fredy G. Osorio, Cleanio Luz-Lima, Anna De Falco, Caique D. A. Lima, Joao Felipe C. Silva, Lanna I. M. Sinimbu, Frederico Gutierrez, Walmir E. Pottker, Felipe A. La Porta, Leonardo A. F. Mendoza, Tahir, Tommaso Del Rosso, Antonio C. Bruno
Summary: A magnetic microscope using Hall effect sensors was constructed in this study, which was built on a gradiometric configuration with a spatial resolution of 620 μm and a magnetic moment sensitivity of 80 nAm². It can generate magnetic fields on samples by employing a small permanent magnet, and the intensity of the applied field can be adjusted by changing the distance between the magnet and the sample. The microscope achieved a spatial field uniformity of 99.7% within a 5.0 mm radius at a distance of 500 μm from the sample surface. The automation of the microscope using the LabVIEW(R) platform makes it a versatile and affordable equipment for laboratories.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Geochemistry & Geophysics
Joshua M. Feinberg, Kathryn K. Hobart
Summary: The magnetism in stalagmites and flowstone can be used to chronicle high-resolution geomagnetic behavior and environmental change, originating from soils and other forms of magnetic minerals. These magnetic minerals become aligned with Earth's magnetic field before being fixed within the speleothem.
Article
Geochemistry & Geophysics
David J. Dunlop
Summary: The study on the magnetic properties of various iron-bearing minerals at different temperatures reveals changes in domain structures, which may lead to thermal unblocking or vortex development in single-domain grains and addition or remobilization of domain walls in multidomain grains. The saturation remanence decreases more rapidly than saturation magnetization with increasing measurement temperature, suggesting thermal effects and domain wall changes in the minerals studied.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Toshitsugu Yamazaki, Jiaxi Li, Takaya Shimono, Toshiya Kanamatsu
Summary: Progress in estimating relative paleointensity (RPI) using marine sediments has contributed to a better understanding of the behavior of the past geomagnetic field. One challenge is that variations in magnetic-mineral assemblages induced by climate can affect RPI records. This study showed that the RPI recording efficiency of magnetofossils is lower than that of detrital unprotected magnetites/maghemites, and changes in their relative abundance do not influence RPI estimations.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Mike J. Jackson, Bruce Moskowitz
Summary: The Verwey transition temperature in magnetite shows a bimodal distribution, with most lithological subsets having a peak around 120 K and one or more additional peaks at lower temperatures. This distribution pattern is a general characteristic of natural magnetites and provides context for interpreting natural processes or conditions during formation or alteration of magnetite.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Luigi Vigliotti, Dario Bilardello, Aldo Winkler, Paola Del Carlo
Summary: A detailed rock magnetic study was conducted on ash samples from different explosive activities of Mount Etna. The study found that magnetic properties can be used as effective factors for discriminating among different eruptive products. The more explosive products were characterized by oxidized Ti-rich titanomagnetites, higher coercivity distributions, and higher magnetizations and susceptibilities. Additionally, the magnetic properties of tachylite-bearing tephra provided a useful tool for studying the fragmentation process and explosive character of volcanic activities.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Zhaowen Pei, Thomas A. Berndt, Liao Chang, Fan Bai, Wyn Williams, Greig A. Paterson
Summary: Magnetosome chains produced by magnetotactic bacteria are important for paleoenvironmental and paleomagnetic records, but the in situ structures of these chains in sediments are not known. This study used micromagnetic simulations to quantify the changes in magnetic signals in response to chain deformation. The results showed that bending/collapse leads to a reduction in coercivity and a transition in domain state of the chain. These findings suggest that hysteresis parameters can be used to assess the degree of chain bending/collapse in magnetofossil-rich sediments, and that deformed magnetosome chains in ancient geological materials retain faithful paleomagnetic records.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Elias N. Mansbach, Jay Shah, Wyn Williams, Clara Maurel, James F. J. Bryson, Benjamin P. Weiss
Summary: Paleomagnetic studies of meteorites offer unique constraints on the evolution of magnetic fields in the early solar system. The analysis of tetrataenite mineral provides a promising opportunity to broaden the spectrum of meteorite groups that can be used for future paleomagnetic studies.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)
Article
Geochemistry & Geophysics
Yuqin Wang, Kunpeng Ge, Wyn Williams, Hui Zhou, Huapei Wang, Lesleis Nagy, Lisa Tauxe, Jiang Wang, Shengbo Liu, Yang Liu
Summary: Recent research indicates that particles in the transitional zone between the single domain and single vortex regions are susceptible to thermal and external magnetic field instabilities, potentially impacting the accuracy of paleomagnetic interpretations. This study simulates the magnetic behavior of specific-shaped magnetite particles to evaluate their internal magnetization characteristics and influence on paleomagnetic observations. The findings reveal the size and dominant features of the magnetically unstable zone, highlighting their significance in paleomagnetic records.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geosciences, Multidisciplinary
Lesleis Nagy, Wyn Williams, Lisa Tauxe, Adrian Muxworthy
Summary: Paleointensities are crucial for understanding Earth's formation and evolution, but current experimental protocols often fail due to the assumption of uniformly magnetized rocks. Non-uniform magnetized grains are more common, causing a multiplicity of stable domain states that affect paleointensity estimation. Recognizing this behavior is vital for obtaining reliable records and enhancing our understanding of Earth.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Thomas L. North, Gareth S. Collins, Thomas M. Davison, Adrian R. Muxworthy, Sarah C. Steele, Roger R. Fu
Summary: By simulating the impact of a shock wave on ALH 84001, researchers were able to determine the meteorite's thermodynamic and physical response, providing insights into its deformation events and ejection from Mars.
Article
Materials Science, Multidisciplinary
R. Moreno, W. Williams, A. R. Muxworthy, G. A. Paterson, D. Heslop
Summary: FORCs is a characterization technique for magnetic materials that is widely used in research fields. Recent experimental works have shown that the interpretation of FORC data lacks understanding, even for simple cases. This study addresses this problem by analytically explaining the meaning of FORC data and proposing a strategy to extract the interaction field between magnetic structures.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Geochemistry & Geophysics
Jing Hu, Yong Zhang, Dong Jia, Adrian Muxworthy, David Selby, Yongxiang Li, Matthew J. J. Brzozowski, Guoqi Wei, Jian Cao, Hongwei Yin, Wei Li
Summary: This study combines paleomagnetic dating analysis and Re-Os isotope dating to resolve the controversial evolution of the Permian reservoir in the Longmen Shan orogen, South China. The results show two remagnetization events and two periods of oil generation and accumulation. This combined approach provides a reliable way to track the sequence of oil formation and accumulation even in complex tectonic settings.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Editorial Material
Geosciences, Multidisciplinary
Richard Douglas Elmore, Adrian R. Muxworthy, Gerhard Heij, W. Crawford Elliott
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
Jose A. P. M. Devienne, Thomas A. A. Berndt, Wyn Williams, Lesleis Nagy
Summary: Sub-micrometer taenite and tetrataenite grains in meteorites can offer reliable paleomagnetic records, with taenite grains of nanometer sizes proving stable over billion-year timescales. The sizes at which stable single-domain structures form coincides with those observed in fast-cooled IVA meteorites, suggesting their suitability for paleomagnetic studies. Moreover, larger grain sizes of coarse-grained taenite also exhibit highly stable vortex states, indicating their potential as reliable records of paleomagnetic fields.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Evelyn B. B. Baker, Adrian R. R. Muxworthy
Summary: In this study, the behavior of grain-growth chemical remanent magnetizations (gCRM) and thermoremanences (TRM) was investigated using a thermally activated Preisach model. It was found that gCRM intensity is more sensitive to growth rate than previously modeled, while TRMs are more sensitive to changes in coercivity distribution and magnetostatic interactions. The results also showed that gCRMs cannot accurately determine ancient magnetic field intensities using conventional methods based on thermoremanence acquisition.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
U. D. Bellon, R. I. F. Trindade, W. Williams
Summary: Quantifying different mineral populations in bulk magnetic experiments improves the analysis of environmental and rock magnetism studies. A new method of unmixing susceptibility components in hysteresis loops is developed, utilizing a modified Gamma-Cauchy exponential model. The model's robustness is tested with synthetic curves, considering the effects of noise, sampling, and proximity of susceptibility components.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Meeting Abstract
Geochemistry & Geophysics
T. L. North, A. R. Muxworthy, G. S. Collins, T. M. Davison
METEORITICS & PLANETARY SCIENCE
(2022)
Meeting Abstract
Geochemistry & Geophysics
T. L. North, G. S. Collins, T. M. Davison, A. R. Muxworthy, S. C. Steele, R. R. Fu
METEORITICS & PLANETARY SCIENCE
(2022)
Article
Geochemistry & Geophysics
Elias N. Mansbach, Jay Shah, Wyn Williams, Clara Maurel, James F. J. Bryson, Benjamin P. Weiss
Summary: Paleomagnetic studies of meteorites have shown that nanoscale tetrataenite grains can carry extremely stable magnetization, making them promising for future research. However, the full potential of tetrataenite for paleomagnetic studies is not yet fully understood and requires further investigation.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)