Mechanism of the parasitic remanence of aluminous goethite [α‐(Fe, Al)OOH]

Liu, Qingsong

doi:10.1029/2004jb003352

Cited by 29 publications

(34 citation statements)

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“…This does not support the origin of unbalance linked to odd number of iron atoms or surface effects in a nanocrystal [Néel, 1962], like recently exemplified on ferritin [Gilles et al, 2002]. Remanence origin cannot be either assigned to the presence of substituted non-magnetic ions, like it is invoked for Al-goethites [Liu et al, 2004].…”

Section: Discussionmentioning

confidence: 99%

“…GT is a natural hydrothermal fibrous goethite from Tarn (S France) that has been manually powdered (at <50 mm). Table 1 provides their X-ray diffraction parameters as well as the maximum unblocking temperature of remanence T B , found close to their Néel point [Rochette and Fillion, 1989;Coey et al, 1995;Ö zdemir and Dunlop, 1996;Liu et al, 2004]. Chemical analysis (using ICP-AES) of GT demonstrates only 0.42 wt.% of impurities, including 0.16% H 2 O, 0.12% SiO 2 , and Ca, K, Ga for the >100 ppm elements, at 500, 400 and 220 ppm, respectively.…”

Section: Samplesmentioning

confidence: 99%

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Non‐saturation of the defect moment of goethite and fine‐grained hematite up to 57 Teslas

Rochette

Mathé

Esteban

et al. 2005

Geophysical Research Letters

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Defect moment of antiferromagnets yields the highest remanent coercivity observed among minerals, and previous studies have been unable to reach saturation of isothermal remanent magnetization (IRM) in some goethite and hematite, even up to 20 Teslas, using resistive Bitter magnets. To go further, acquisition of IRM at room temperature has been monitored on various natural and synthetic goethite and hematite samples in pulsed magnetic fields up to 57 Teslas. “Coarse” hematite is saturated around 5 T, and low unblocking temperature (TB, i.e. with low crystallinity or Al substitution) goethites saturate around 20 T. Higher TB goethites and a Mn‐bearing fine‐grained hematite are still not saturated even at 57 T, with only 2 to 10 percent of the maximum IRM acquired in 3 T. Half acquisition fields are mostly above 10 T. This indicates that usual rock magnetic techniques strongly underestimate the contribution of such minerals to remanence. IRM acquisition is strongly irreversible: in some samples a 57 T backfield is unable to erase a previous 38 T IRM. A field induced defect diffusion model is put forward to account for remanence acquisition in these materials.

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Section: Discussionmentioning

confidence: 99%

Section: Samplesmentioning

confidence: 99%

Non‐saturation of the defect moment of goethite and fine‐grained hematite up to 57 Teslas

Rochette

Mathé

Esteban

et al. 2005

Geophysical Research Letters

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“…Magnetic particle size determination helps to identify such environmental changes. For example, iron reduction gives rise to magnetite or maghemite neoformation in topsoil as SP grains (diameter, d < 20 nm), which have high χ [ Zhou et al , 1990], or as slightly larger SD particles (20 nm < d < 1 μ m) with large ARM values [ Liu et al , 2004a]. SD/SP particles in soils provide strong indications of iron cycling.…”

Section: Cycling Of Iron Minerals In Naturementioning

confidence: 99%

Environmental magnetism: Principles and applications

Liu

Roberts

Larrasoaña

et al. 2012

Reviews of Geophysics

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In environmental magnetism, rock and mineral magnetic techniques are used to investigate the formation, transportation, deposition, and postdepositional alterations of magnetic minerals under the influences of a wide range of environmental processes. All materials respond in some way to an applied magnetic field, and iron‐bearing minerals are sensitive to a range of environmental processes, which makes magnetic measurements extremely useful for detecting signals associated with environmental processes. Environmental magnetism has grown considerably since the mid 1970s and now contributes to research in the geosciences and in branches of physics, chemistry, and biology and environmental science, including research on climate change, pollution, iron biomineralization, and depositional and diagenetic processes in sediments to name a few applications. Magnetic parameters are used to routinely scan sediments, but interpretation is often difficult and requires understanding of the underlying physics and chemistry. Thorough examination of magnetic properties and of the environmental processes that give rise to the measured magnetic signal is needed to avoid ambiguities, complexities, and limitations to interpretations. In this review, we evaluate environmental magnetic parameters based on theory and empirical results. We describe how ambiguities can be resolved by use of combined techniques and demonstrate the power of environmental magnetism in enabling quantitative environmental interpretations. We also review recent developments that demonstrate the mutual benefit of environmental magnetism from close collaborations with biology, chemistry, and physics. Finally, we discuss directions in which environmental magnetism is likely to develop in the future.

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“…Such a high coercivity is due to the weak parasitic but hard ferromagnetism of goethite (Dekkers 1989;Liu et al 2004b;Rochette et al 2005).…”

Section: Decomposition Of Irm Acquisition Curvesmentioning

confidence: 99%

Characterizing magnetic mineral assemblages of surface sediments from major Asian dust sources and implications for the Chinese loess magnetism

et al. 2015

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Eolian dust plays an important role in the Earth's climate system. Environmental magnetism has been widely used to trace dust variations at different spatial and temporal scales. However, the magnetic properties of sediments from key dust sources have not been well determined. In this study, surface samples from potential dust sources in inner Eastern Asia were systematically investigated. Our results indicate that ferrimagnetic and antiferromagnetic minerals are both present in surface sediments and that they have broad grain size distributions. Ferrimagnetic components are dominated by partially oxidized coarse-grained (pseudo-single domain and multi-domain) lithogenic magnetite particles with minor contributions from pedogenic fine-grained (single domain and superparamagnetic) particles. Antiferromagnetic hematite can be classified into three groups in terms of diffuse reflectance spectroscopy (DRS) band positions (P 560 nm , P 545 nm , and P 535 nm , where numbers indicate the DRS band wavelength for hematite). The first group (P 560 nm ) is the coarse-grained hematite of lithogenic origin and is mostly confined to western China. The P 535 nm group is of pedogenic origin. The P 545 nm group is an intermediate phase that is present both in surface samples from the source regions and in loess. Therefore, the P 545 nm and P 535 nm groups are related to eolian inputs to the Chinese Loess Plateau and pedogenic processes, respectively. In addition, significant differences exist between the magnetic properties of eolian material from sources and depositional regions due to gravitational sorting. These insights provide strong constraints on interpretation of dust signals recorded by the Chinese loess and marine sediments from the North Pacific Ocean.

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Mechanism of the parasitic remanence of aluminous goethite [α‐(Fe, Al)OOH]

Cited by 29 publications

References 28 publications

Non‐saturation of the defect moment of goethite and fine‐grained hematite up to 57 Teslas

Non‐saturation of the defect moment of goethite and fine‐grained hematite up to 57 Teslas

Environmental magnetism: Principles and applications

Characterizing magnetic mineral assemblages of surface sediments from major Asian dust sources and implications for the Chinese loess magnetism

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