Mössbauer spectroscopy of magnetic minerals in basalt on Earth and Mars

Gunnlaugsson, H. P.; Rasmussen, H.; Kristjánsson, Leó; Steinþórsson, S.; Helgason, Örn; Nørnberg, P.; Madsen, M. B.; Mørup, Steen

doi:10.1007/s10751-008-9714-9

Cited by 13 publications

(7 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fitted hyperfine parameters are given in Table 3. The iron (3+) does not show a magnetic order at 78 K. Similar doublets have been reported for terrestrial and martian basalts but usually not assigned (Gunnlaugsson et al 2006(Gunnlaugsson et al , 2008. Thompson et al (2011) have recently reported the Mössbauer spectra of a basaltic soil subjected to a gradient in precipitation.…”

Section: Nature Of the Fe-ti Oxidessupporting

confidence: 67%

“…Mineralogically unspecific iron(3+) is also identified. This signal can be interpreted as iron(3+) in pyroxene or a nanophase ferric oxide alteration product (Gunnlaugsson et al 2008) as well as a small fraction of superparamagnetic grains (Rivas-Sanchez et al 2009;Roggwiller & Kundig 1973). Assuming a continuous distribution of the size of magnetic grains and knowing the exponential nature of SD relaxation times, temperature variations may affect the Mössbauer spectra.…”

Section: Nature Of the Fe-ti Oxidesmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic interactions at the origin of abnormal magnetic fabrics in lava flows: a case study from Kerguelen flood basalts

Fanjat

Camps

Щербаков³

et al. 2012

Geophysical Journal International

View full text Add to dashboard Cite

International audienceAnisotropy of low-field magnetic susceptibility (AMS) of basaltic lava flows can give some clues about post-emplacement tilting occurring in volcanic sequences. Such a study has been carried out on a sequence of 19 successive lava flows from Kerguelen Archipelago. Surprisingly, two different patterns were observed. The first one - herein called normal fabric - is consistent with the lava-flow direction inferred from geological observations, whereas the second one observed for about 70 per cent of the analysed samples - herein called abnormal fabric - appears to be unrelated to the shear history of the lava flows during their emplacements. These abnormal fabrics are not strictly inverse fabric but seem to have a more complex origin. The unusual nature of these abnormal fabrics has been confirmed by lattice preferred orientation of plagioclases obtained from high-resolution electron backscattered diffraction measurements. The aim of this study is to propose a physical interpretation of these fabrics. A first step in our understanding was to clearly identify the nature and the magnetic properties of the Fe-Ti oxides assemblage. Thus, we present a comprehensive rock magnetic analysis relying on low- and high-temperature thermomagnetic curves (K-T), crossover diagrams, first-order reversal curves, ore-microscopy, Mössbauer measurements and electron backscattered images. We found that in the present case the abnormal fabrics are probably linked to a mixture of prevailing single domain (SD) strongly interacting grains population and a subsidiary multidomain grains population. SD grains are identified as small magnetite crystallized within the interstitial glass in globular aggregates along the silicate framework. Then a question arises: to what extent such SD interacting grains in globular aggregates can affect the magnetic susceptibility and its anisotropy? To answer this question, we developed a physical model in which the total energy density of an SD grain with an uniaxial anisotropy is minimized. In this model, the distribution function of the direction of the magnetic interaction field is comprised between two boundary states. It is either isotropic, which formally corresponds to the thermal demagnetized state, or it is ordered, which formally corresponds to the Alternative Field demagnetized state. We show that in both cases the degree of anisotropy decreases as the interaction field increases. Thus, we conclude that the abnormal fabric encountered in this study can be simply explained by strong magnetostatic interactions that would explain the large scattering of AMS often observed in basaltic lava flows

show abstract

Section: Nature Of the Fe-ti Oxidessupporting

confidence: 67%

Section: Nature Of the Fe-ti Oxidesmentioning

confidence: 99%

Magnetic interactions at the origin of abnormal magnetic fabrics in lava flows: a case study from Kerguelen flood basalts

Fanjat

Camps

Щербаков³

et al. 2012

Geophysical Journal International

View full text Add to dashboard Cite

show abstract

“…Sextet 2 and Sextet 3 exhibit considerable a-line broadening, with the latter having the highest line width or Γ value (< 1.83 mm/s). This is probably due to the random distribution of iron cations in different valences and vacancies (Gunnlaugsson et al 2008 (namely M1 and M2) which are completely overlapped at temperature below ca 300 K. Natural olivine is a member of a continuous solid solution series, i.e., Mg 2 SiO 4 (forsterite) and Fe 2 SiO 4 (fayalite). In this series, the Fe 2+ is partially replaced by Mg…”

Section: Resultsmentioning

confidence: 99%

Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Hassan

Dekan

2013

Mineralogia

View full text Add to dashboard Cite

Abstract. Olivine basalts from southern Egypt were studied by 57 Fe Mössbauer spectroscopy at 297 and 77 K, and by optical microscopy and X-ray diffraction. The 57Fe Mössbauer spectra show three-magnetic sextets, three doublets of ferrous (Fe 2+ ), and a weak ferric (Fe 3+ ) doublet that is attributable to a nanophase oxide (npOx). The magnetic sextets relate to titanomagnetite and the Fe 2+ doublets to olivine, pyroxene, and ulvöspinel. Variations in the hyperfine parameters of the various Fe components are attributed to changes in the local crystal chemistry. The intensity of oxidation (Fe 3+ /ΣFe) in the rocks varies from 20-27% with the oxidized iron largely residing in the titanomagnetite.

show abstract

“…The masked sectors of microtome slices labelled Sect 1 and Sect 2, that indicate high amount of magnetic phases, show no significant presence of ilmenite, suggesting that these have not originated via solvulus-exsolution of titanomagnetite [7]. This rather suggests formation from oxidation of olivine [8].…”

Section: Discussionmentioning

confidence: 95%

Fe mineralogy of rocks from the Vredefort impact structure investigated with Mössbauer spectroscopy

2008

Self Cite

View full text Add to dashboard Cite

The Vredefort impact structure in South Africa is the largest and oldest remnant impact structure on Earth. Observations from above the crater reveal lower than average magnetic field intensities, but the rocks in the crater have been shown to possess much higher magnetic intensities than the regional average that varies on a centimeter scale. Various mechanisms, including the presence of single domain magnetite structures, have been proposed for this anomaly. Mössbauer spectroscopy has been applied to study the Fe-mineralogy of samples from near the centre of the Vredefort crater. Transmission Mössbauer measurements on bulk and microtomics sections of samples showed that the magnetic minerals were magnetite and hematite, and we suggest that oxidation of olivine during the impact is responsible for the magnetic properties of the rocks.

show abstract

Mössbauer spectroscopy of magnetic minerals in basalt on Earth and Mars

Cited by 13 publications

References 29 publications

Magnetic interactions at the origin of abnormal magnetic fabrics in lava flows: a case study from Kerguelen flood basalts

Magnetic interactions at the origin of abnormal magnetic fabrics in lava flows: a case study from Kerguelen flood basalts

Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Fe mineralogy of rocks from the Vredefort impact structure investigated with Mössbauer spectroscopy

Contact Info

Product

Resources

About