Frequency dependence of low-temperature susceptibility peak in some titanomagnetites

Radhakrishnamurty, C.; Likhite, S.D.

doi:10.1016/0031-9201(93)90062-e

Cited by 22 publications

(19 citation statements)

References 10 publications

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“…After immersion of all three samples in liquid nitrogen, their k values show a similar change as they heat up to room temperature (Figure 3a). The shape of the k vs. T curves is characteristic of rocks containing multidomain magnetite [Radhakrishnamurty and Likhite, 1993] or 1ow-Ti titanomagnetite [Senanayake and McElhinny, 1982]. Each curve show peak, or isotropic point between 137 K and 143 K. This peak is known to occur at about 123 K in pure magnetite at the frequency employed in our induction coil (13.8 kHz) [Radhakrishnamurty and Likhite, 1993].…”

Section: Paper Number 97jb02670mentioning

confidence: 92%

“…The shape of the k vs. T curves is characteristic of rocks containing multidomain magnetite [Radhakrishnamurty and Likhite, 1993] or 1ow-Ti titanomagnetite [Senanayake and McElhinny, 1982]. Each curve show peak, or isotropic point between 137 K and 143 K. This peak is known to occur at about 123 K in pure magnetite at the frequency employed in our induction coil (13.8 kHz) [Radhakrishnamurty and Likhite, 1993]. However, variations in the temperature of this isotropic point and even its suppression are known to occur in titanomagnetites and nonstoichiometric, oxidized magnetites [Senanayake and McElhinny, 1982; Ozdemir et al, 1993].…”

Section: Paper Number 97jb02670mentioning

confidence: 99%

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Magmatic fabric acquisition mechanisms in a syenite: Results of a combined anisotropy of magnetic susceptibility and image analysis study

Launeau¹,

Cruden²

1998

J. Geophys. Res.

145

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Section: Paper Number 97jb02670mentioning

confidence: 92%

Section: Paper Number 97jb02670mentioning

confidence: 99%

Magmatic fabric acquisition mechanisms in a syenite: Results of a combined anisotropy of magnetic susceptibility and image analysis study

Launeau¹,

Cruden²

1998

J. Geophys. Res.

145

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“…In this context, the observed frequency‐dependent susceptibility below 150 K probably also results from the low‐temperature behaviour of titanomagnetite (e.g. Radhakrishnamurthy & Likhite 1993; Moskowitz et al 1998).…”

Section: Low‐temperature Susceptibilitymentioning

confidence: 95%

The magnetism of a glacial aeolianite sequence from Lanzarote (Canary Islands): coupling between luvic calcisol formation and Saharan dust trapping processes during wet deposition events off northwestern Sahara

Williamson

Jackson

Banerjee

et al. 2004

Geophysical Journal International

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S U M M A R YIn order to better document the climatic origin of pedogenized loess deposits west of Sahara, rock-magnetic measurements were performed on a Last Glacial coastal sand sequence from La Mala (LM) quarry (Lanzarote, Canary Islands) containing six interbedded loess-palaeosol units. Hysteresis and susceptibility data point to a coarse-grained magnetic enhancement in the coastal sand, which contrasts with the superparamagnetic (SP) to pseudo-single domain (PSD) behaviour of the Saharan loess and palaeosol. High-and low-temperature experiments show that oxidized titanomagnetite contributions dominate in the sand, while fine-grained (SP to PSD) iron oxidation products such as maghemite and goethite are evidenced in the Saharan loess/palaeosol units. At room temperature, the detrital PSD-multidomain titanomagnetite contribution of local origin is tentatively estimated from the AC-field dependence of magnetic susceptibility. Surface oxidation of detrital spinel grains and authigenesis of fine-grained iron oxides (including SP goethite) are proposed to explain the magnetic properties of the primarily fine, Saharan-dust-bearing material.The dry, local climate of the present-day and Late Holocene means that loess deposits are not preserved. The six pedogenized loess units, however, point to dust trapping under semi-arid, wetter conditions, probably illustrating periods of reduced latitudinal temperature gradients and climate variability of the North Atlantic climate, respectively. These findings suggest that both the Canary palaeosol and its content of (ultra)fine iron oxide might be constrained by (wet) deposition and trapping of fine Saharan dust.

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“…Coarse PSD and MD particles often have a χ fd peak at ∼50 K due to relaxation of domain walls in magnetite or titanomagnetite [ Šimša et al , 1985; Radhakrishnamurty and Likhite , 1993; Moskowitz et al , 1998; Skumryev et al , 1999; Kosterov , 2003; Lagroix et al , 2004], which can be confused with signatures due to SP particles with sizes of several nm. Such a peak has been observed for soil samples from Argentina.…”

Section: Ambiguities Of Magnetic Parameters and Interpretationsmentioning

confidence: 99%

Environmental magnetism: Principles and applications

Liu

Roberts

Larrasoaña

et al. 2012

Reviews of Geophysics

578

405

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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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Frequency dependence of low-temperature susceptibility peak in some titanomagnetites

Cited by 22 publications

References 10 publications

Magmatic fabric acquisition mechanisms in a syenite: Results of a combined anisotropy of magnetic susceptibility and image analysis study

Magmatic fabric acquisition mechanisms in a syenite: Results of a combined anisotropy of magnetic susceptibility and image analysis study

The magnetism of a glacial aeolianite sequence from Lanzarote (Canary Islands): coupling between luvic calcisol formation and Saharan dust trapping processes during wet deposition events off northwestern Sahara

Environmental magnetism: Principles and applications

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