Magnetic anisotropy of hematite natural crystals: increasing low-field strength experiments

Guerrero-Suarez, S.; Martín-Hernández, F.

doi:10.1007/s00531-011-0666-y

Cited by 17 publications

(16 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The mean corrected anisotropy degree ( P j ) is relatively high (1.05) (Figure a) compared with the typical values within sediments dominated by paramagnetic minerals. However, hematite can have very high (>100) anisotropies [ Guerrero‐Suarez and Martín‐Hernández , ; Tarling and Hrouda , ] and this high value may reflect the presence of a minor amount of hematite contributing to the anisotropy.…”

Section: Resultsmentioning

confidence: 99%

Magnetic fabrics in the basal ice of a surge-type glacier

Fleming

Lovell

Stevenson

et al. 2013

J. Geophys. Res. Earth Surf.

View full text Add to dashboard Cite

[1] Anisotropy of magnetic susceptibility (AMS) has been shown to provide specific useful information regarding the kinematics of deformation within subglacially deformed sediments. Here we present results from debris-rich basal glacier ice to examine deformation associated with glacier motion. Basal ice samples were collected from Tunabreen, a polythermal surge-type glacier in Svalbard. The magnetic fabrics recorded show strong correlation with structures within the ice, such as sheath folds and macroscopic stretching lineations. Thermomagnetic, low-temperature susceptibility, varying field susceptibility, and isothermal remanent magnetism acquisition experiments reveal that the debris-rich basal ice samples have a susceptibility and anisotropy dominated by paramagnetic phases within the detrital sediment. Sediment grains entrained within the basal ice are inferred to have rotated into a preferential alignment during deformation associated with flow of the glacier. An up-glacier directed plunge of magnetic lineations and subtle deviation from bulk glacier flow at the margins highlight the importance of noncoaxial strain during surge propagation. The results suggest that AMS can be used as an ice petrofabric indicator for investigations of glacier deformation and interactions with the bed.

show abstract

Section: Resultsmentioning

confidence: 99%

Magnetic fabrics in the basal ice of a surge-type glacier

Fleming

Lovell

Stevenson

et al. 2013

J. Geophys. Res. Earth Surf.

View full text Add to dashboard Cite

show abstract

“…The maximum value of susceptibility ranges between 0.2 − 0.9 SI, except sample 17B whose maximum susceptibility is one order of magnitud less, 0.02 SI. Each of these curves can be classified as one of the three categories in hematite natural crystals, as already reported by Guerrero-Suarez & Martín-Hernández (2012 show that there is a big difference between the maximum value of susceptibility at 300 K and at 77 K, except in sample 1A. Maximum susceptibility decreases ∼ 33% at 77 K in samples 4A, 1G and 4E, one order of magnitude less in samples 2E and 17B, and two orders of magnitude less in samples 8A …”

Section: Natural Crystal Samplesmentioning

confidence: 88%

“…In this work, rock magnetic measurements have been realized at temperature below Morin transi-Several factors have been analyzed like possible controllers of the initial susceptibility behaviours reported in hematite by Guerrero-Suarez & Martín-Hernández (2012). The studied parameters are grain size, magnetic phases different to hematite, magnetic parameters and domain wall displacements.…”

Section: Hematite At Low Temperaturementioning

confidence: 99%

“…Field-dependent susceptibility can cause variations in the parameters of the AMS ellipsoid and originates mistaken interpretations in magnetic fabrics studies and rock magnetism (Hrouda 2002;Guerrero-Suarez & Martín-Hernández 2012). The variations of the susceptibility with field strength of some minerals have been modelled mathematically by Hrouda et al (2006) giving rise to a useful tool to compute separation of magnetic subfabrics (Hrouda 2009;Hrouda & Ježek 2014), identification…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Haematite natural crystals: non-linear initial susceptibility at low temperature

Guerrero-Suarez

Martín-Hernández

2016

Geophys. J. Int.

Self Cite

View full text Add to dashboard Cite

SUMMARYSeveral works have reported that hematite has non-linear initial susceptibility at room temperature, like pyrrhotite or titanomagnetite, but there is no explanation for the observed behaviours yet. This study sets out to determine which physical property (grainsize, foreign cations content, domain walls displacements) controls the initial susceptibility. The performed measurements include microprobe analysis to determine magnetic phases different to hematite; initial susceptibility (300 K); hysteresis loops, SIRM and backfield curves at 77 K and 300 K to calculate magnetic parameters and minor loops at 77 K, to analyze initial susceptiblity and magnetization behaviours below Morin transition. The magnetic moment study at low temperatura is completed with measurements of Zero Field Cooled-Field Cooled (ZFC-FC) and AC-susceptibility in a range from 5 − 300 K. The minor loops show that the non-linearity of initial susceptibility is closely related to Barkhausen jumps. Because of initial magnetic susceptibility is controlled by domain structure it is difficult to establish a mathematical model to separate magnetic subfabrics in hematite-bearing rocks.

show abstract

“…AMS was determined in a field of 200 A/m, which is higher than the geomagnetic field (approximately 40 A/m). Because some minerals, e.g., pyrrhotite (Martin‐Hernandez et al, ; Worm, ; Worm et al, ) or hematite (Guerrero‐Suarez & Martin‐Hernandez, ), have been reported to display field dependence of susceptibility and AMS, test measurements were made on a subset of samples in 5 A/m, 40 A/m, and 200 A/m. These showed no field dependence on either mean susceptibility, principal susceptibility directions, AMS degree, or AMS shape.…”

Section: Bjerkreim Sokndal (Bks) Case Studymentioning

confidence: 99%

Effects of Magnetic Anisotropy on Total Magnetic Field Anomalies

Biedermann

McEnroe

2017

JGR Solid Earth

View full text Add to dashboard Cite

Modeling of magnetic anomaly data is a powerful technique to gain information on the shape of subsurface rock bodies. Most models are based on the assumption that the magnetization in the source body is parallel to the direction of the Earth's magnetic field. It has long been recognized that remanent magnetization affects the magnetization direction, intensity and shape of the anomaly, and therefore the interpreted structure. The effects of anisotropy, however, have only received little attention so far. This study uses synthetic models and a case study to investigate how anisotropy affects magnetization and anomalies over a thick dipping sheet and determines expected errors in interpreted magnetic properties and geometry of the source body for various anisotropy degrees and field inclinations. Anisotropy affects both the shape and amplitude of anomalies. For an oblate uniaxial fabric with the minimum susceptibility normal to the sheet and P = 1.5, errors in interpreted dip are up to 12°, depending on the field inclination, dip, and profile orientation, and errors in estimated mean susceptibility are up to −30%/+20%, if anisotropy is not taken into account during modeling. These effects are larger for higher degrees of anisotropy. A case study over the megacyclic unit IVe′ layer in the Bjerkreim Sokndal layered intrusion, Norway, investigates the contributions of (an)isotropic induced and remanent magnetizations to the total field anomalies. There, the influence of anisotropy is mainly related to remanence deflection. The results shown here will help to further improve interpretation of magnetic potential field data.

show abstract

Magnetic anisotropy of hematite natural crystals: increasing low-field strength experiments

Cited by 17 publications

References 28 publications

Magnetic fabrics in the basal ice of a surge-type glacier

Magnetic fabrics in the basal ice of a surge-type glacier

Haematite natural crystals: non-linear initial susceptibility at low temperature

Effects of Magnetic Anisotropy on Total Magnetic Field Anomalies

Contact Info

Product

Resources

About