The effect of magnetic anisotropy on paleomagnetic directions in high-grade metamorphic rocks from the Juiz de Fora Complex, SE Brazil

Raposo, María Irene Bartolomeu; D’Agrella-Filho, Manoel S.; Siqueira, Roberto

doi:10.1016/s0012-821x(03)00065-7

Cited by 19 publications

(2 citation statements)

References 35 publications

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“…Remanence correction for compaction-induced inclination anomaly has been successfully applied in several previous studies (e.g. Jackson et al, 1991;Kodama, 1997;Raposo et al, 2003;references therein). AMS is potentially a good indicator of compaction-induced shallowing of remanence inclination.…”

Section: Magnetic Mineralogy Ams Irm and Remanence Correctionmentioning

confidence: 99%

New late Proterozoic paleomagnetic pole for the Rio de la Plata craton: Implications for Gondwana

Rapalini

2006

Precambrian Research

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Section: Magnetic Mineralogy Ams Irm and Remanence Correctionmentioning

confidence: 99%

New late Proterozoic paleomagnetic pole for the Rio de la Plata craton: Implications for Gondwana

Rapalini

2006

Precambrian Research

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“…Flow structure, one of the characteristics of rhyolite lava, may offer a clue about the changes in the direction of remanent magnetization in rhyolite lava during the development of the structure-heterogeneous texture in rocks may cause the deflection of the remanent magnetization to a direction different from the original one. In the case of metamorphic rocks, for example, the deflection of the direction of characteristic remanent magnetization was observed to be a function of the degree of anisotropy of magnetic susceptibility (Bartolomeu Raposo et al, 2003). The disagreement between the observed paleomagnetic direction of rhyolite lava and the expected one may be a function of the development of the flow structure.…”

Section: Introductionmentioning

confidence: 96%

Paleomagnetic investigation of rhyolite lava: Is rhyolite with clearly marked flow structure a high-fidelity geomagnetic field recorder?

et al. 2013

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Rhyolite is a common volcanic rock; however, few studies have focused on the remanent magnetization of rhyolite lava, and few paleomagnetic studies have successfully investigated rhyolite lavas. We suspect that problems associated with paleomagnetic studies of rhyolite may be due to the nearly ubiquitous flow structure in rhyolite lava. In this study, we examined a thick rhyolite lava flow with clearly marked flow structure to assess its ability to record a consistent paleomagnetic direction, using material penetrated by two drill cores. Progressive thermal demagnetization isolated two magnetization components. A high-temperature component from each of the two cores yields inclinations that differ from each other. The low-temperature component had those that agreed with each other, and were also consistent with the direction expected from a geocentric axial dipole field. The modification of direction of the high-temperature component may be explained by post-magnetization acquisition tilting. The development of flow structure also leads to distortion of directions of the component, which is observed at stratigraphic positions where the volume fraction of light-colored parts of the flow structure >30%. In the case of silicic lava, the low-temperature component may retain directions parallel to the ambient field direction at the time of lava emplacement.

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Preliminary Magnetic Susceptibility Characteristics of the Bharati Promontory (Grovness Peninsula), Larsemann Hills, Prydz Bay Region, East Antarctica

Pandit

Wall

2014

Journal of the Geological Society of India

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The coastal tract of the Prydz Bay region in the East Antarctica exposes Archean to Late Proterozoic magmatic and medium- to high grade (amphibolite – granulite facies) metamorphic rocks. The para- and ortho gneisses from the Bharati promontory (Grovness Peninsula) forming a part of the Larsemann Hills in the southern segment of Prydz Bay were investigated for magnetic characterization. In this small peninsula the upper amphibolite facies gneisses occur as NE-trending bands. The para-gneisses show a range of mineral assemblages (± cordierite ± sillimanite ±garnet) while ortho-gneiss mineralogy includes quartz, feldspar, biotite, garnet. All the lithological units in Bharati promontory contain ubiquitous magnetite, however, with wide variation in the volume proportions. This has resulted in a wide range in magnetic susceptibility (10−4 to 10−2 SI). Magnetic foliations show a correspondence with the general trend of lithounits (050° NE) and define a resulting geometry of mainly D1 and D2 foliations. The magnetic lineations show a preferred orientation with moderate easterly plunge (mean vector 093/36). The findings have implications for the magnetic field survey because such fabrics would impart a strong horizontal component of induced magnetization.

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The effect of magnetic anisotropy on paleomagnetic directions in high-grade metamorphic rocks from the Juiz de Fora Complex, SE Brazil

Cited by 19 publications

References 35 publications

New late Proterozoic paleomagnetic pole for the Rio de la Plata craton: Implications for Gondwana

New late Proterozoic paleomagnetic pole for the Rio de la Plata craton: Implications for Gondwana

Paleomagnetic investigation of rhyolite lava: Is rhyolite with clearly marked flow structure a high-fidelity geomagnetic field recorder?

Preliminary Magnetic Susceptibility Characteristics of the Bharati Promontory (Grovness Peninsula), Larsemann Hills, Prydz Bay Region, East Antarctica

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