Magnetic properties of marine limestones

Lowrie, William; Heller, Friedrich

doi:10.1016/0148-9062(83)91673-x

Cited by 73 publications

(92 citation statements)

References 45 publications

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“…Such maghemite is an oxidation product of magnetite, that is, an indication of low temperature oxidation and weathering (Lowrie and Heller, 1982;O'Reilly, 1984). Metastable maghemite transforms to stable hematite upon heating to temperatures above 250°C (Ozdemir, 1990).…”

Section: Rock Magnetic Properties Of the Archaeological Samples And Tmentioning

confidence: 99%

Preliminary Rock Magnetic Study of Archaeomagnetic Samples from Bulgarian Prehistoric Sites.

Jordanova

Petrovský²,

Kovacheva

1997

J. geomagn. geoelec

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Rock magnetic properties of archaeomagnetic samples taken from ovens are studied. Thermal demagnetization of saturation remanences and other studies reveal the presence of: (titano)magnetite, iron oxyhydroxides, and maghemite with Tb -650°C which is stable with respect to inversion. During thermal demagnetization the soft IRM component (0.06 T) is always the strongest one, indicating the importance of the (titano)magnetite contribution. A break-up in the values of coercivity H with respect to initial mass-specific magnetic susceptibility (X) occurs at X -1.5 x 10-6 m3/kg and separates poorer from better quality samples in the palaeointensity experiment. Separation of bad and good Thellier experiments is also observed in the relation between the coercivities and the concentration-independent parameter SIRM/X. Thus, the poor quality of the palaeointensity experiments for some samples can probably be ascribed to the presence of weathering products and MD magnetite grains while the good quality of these experiments is related to "soft" hysteresis properties and a broad unblocking temperature spectrum.

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Section: Rock Magnetic Properties Of the Archaeological Samples And Tmentioning

confidence: 99%

Preliminary Rock Magnetic Study of Archaeomagnetic Samples from Bulgarian Prehistoric Sites.

Jordanova

Petrovský²,

Kovacheva

1997

J. geomagn. geoelec

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“…Although the magnetic and physical properties of ferrimagnetic iron sulfides and especially monoclinic pyrrhotite (FeTSs) have been rather extensively described [1][2][3][4][5][6], pyrrhotite is quoted as a minor magnetic mineral in most paleomagnetic textbooks. In fact, as will be discussed in this paper, the prevalence of pyrrhotite, its strong and stable magnetic properties make it potentially as important as magnetite as carrier of a paleomagnetic signal.…”

Section: Introductionmentioning

confidence: 99%

Magnetic transition at 30–34 Kelvin in pyrrhotite: insight into a widespread occurrence of this mineral in rocks

Rochette

Fillion

Mattéi

et al. 1990

Earth and Planetary Science Letters

273

175

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A characteristic magnetic transition at 30-34 K is shown to provide a powerful tool for the identification of pyrrhotite with concentration down to 10 ppm through the same low-temperature techniques as applied to magnetite and hematite, extended down to liquid helium temperature. A review of rock magnetic and petrological data on pyrrhotite suggests that this mineral should be considered as a major carrier of paleomagnetic signals. Unblocking temperature up to 350 °C and extreme resistance against AF may be encountered in fine grained pyrrhotite.

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“…Thermal demagnetization generally is required to obtain primary magnetizations from reddish-colored pelagic sediments (e.g., Steiner, 1977;Lowrie and Heller, 1982;Ogg, 1983). Therefore, the earlier paleomagnetic study of this facies at Site 261, prior to common usage of thermal techniques, was unsuccessful in obtaining mixed polarity by application of AF demagnetization of 5 mT (Jarrard, 1974).…”

Section: Reddish-brown Claystone (Sites 261 and 765)mentioning

confidence: 99%

Lower Cretaceous Magnetostratigraphy and Paleolatitudes off Northwest Australia, ODP Site 765 and DSDP Site 261, Argo Abyssal Plain, and ODP Site 766, Gascoyne Abyssal Plain

Ogg¹,

Kodama²,

Wallick³

1992

Proceedings of the Ocean Drilling Program

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Lower Cretaceous sediments were sampled for magnetostratigraphy at three sites. ODP Site 765 and DSDP Site 261, in the Argo Abyssal Plain, consist primarily of brownish-red to gray claystone having hematite and magnetite carriers of characteristic magnetization. ODP Site 766, in the Gascoyne Abyssal Plain, consists mainly of dark greenish-gray volcaniclastic turbidites with magnetite as the carrier of characteristic magnetization. Progressive thermal demagnetization (Sites 765 and 261) or alternating field demagnetization (Site 766) yielded well-defined polarity zones and a set of reliable paleolatitudes.Magnetic polarity chrons were assigned to polarity zones using biostratigraphic correlations. Late Aptian chron M"-l"r, a brief reversed-polarity chron younger than MOr, is a narrow, 40-cm feature delimited in Hole 765C. Early Aptian reversed-polarity chron MOr is also present in Hole 765C. Polarity chrons Mir through M3r were observed in the Barremian of all three sites. Valanginian and Hauterivian polarity chrons can be tentatively assigned to polarity zones only in Hole 766A.The paleolatitude of this region remained at 35° to 37°S from the Berriasian through the Aptian. During this interval, there was approximately 16° of clockwise rotation, with the oriented sample suites of Site 765 displaying a Berriasian declination of 307° to an Aptian declination of 323°. These results are consistent with the interpolated Early Cretaceous apparent polar wander for Australia, but indicate that this region was approximately 5° farther north than predicted.

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Magnetic properties of marine limestones

Cited by 73 publications

References 45 publications

Preliminary Rock Magnetic Study of Archaeomagnetic Samples from Bulgarian Prehistoric Sites.

Preliminary Rock Magnetic Study of Archaeomagnetic Samples from Bulgarian Prehistoric Sites.

Magnetic transition at 30–34 Kelvin in pyrrhotite: insight into a widespread occurrence of this mineral in rocks

Lower Cretaceous Magnetostratigraphy and Paleolatitudes off Northwest Australia, ODP Site 765 and DSDP Site 261, Argo Abyssal Plain, and ODP Site 766, Gascoyne Abyssal Plain

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