Hostname: page-component-78c5997874-8bhkd Total loading time: 0 Render date: 2024-11-03T08:48:07.275Z Has data issue: false hasContentIssue false

Investigations of Some Magnetic and Mineralogical Properties of the Laschamp and Olby Flows, France

Published online by Cambridge University Press:  20 January 2017

John Whitney
Affiliation:
Geophysics Program, AK-50, University of Washington, Seattle, WA 98195
H. P. Johnson
Affiliation:
Geophysics Program, AK-50, University of Washington, Seattle, WA 98195
Shaul Levi
Affiliation:
Geophysics Program, AK-50, University of Washington, Seattle, WA 98195
Bernard W. Evans
Affiliation:
Department of Geological Sciences, AK-20, University of Washington, Seattle, WA 98195

Abstract

Rock-magnetic, paleomagnetic and petrologic properties of samples from the Laschamp and Olby basalt formations in France were studied to aid in determining the validity of the Laschamp geomagnetic field reversal reported by Bonhommet and Babkine. The Laschamp flow contains ilmenomagnetite, with partial alteration of the magnetite to hematite. Ilmenomagnetite in the Olby flow has largely recrystallized at high temperatures to a composite mozaic intergrowth of pseudobrookite, titanohematite and magnesioferrite, with rare residual magnetite and lamellae of ilmenite. The remanent magnetization is stable and resides primarily in single-domain magnetite particles. Our results indicate that the magnetizations of the Laschamp and Olby flows faithfully record the direction of the ambient magnetic field in which they cooled.

Type
Original Articles
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ade-Hall, J.M., Khan, M.A., Dagley, , P., Wilson, R.L. 1968. A detailed opaque petrological and magnetic investigation of a single tertiary lava flow from Skye, Scotland—I. Geophysical Journal of the Royal Astronomical Society 16 375388.Google Scholar
Bonhommet, N. (1970). Discovery of a new event in the Brunhes period at Laschamp (France) In Palaeogeophysics (Runcorn, S.K.Ed.),pp. 159163. Academic Press New York Google Scholar
Bonhommet, N., Babkine, J. (1967). Sur la présence d’animantations inversées dans la Chaine des Puys Comptes Rendus Academie des Sciences Paris 264 Série B, 9294.Google Scholar
Bonhommet, N. Zähringer, J. (1969). Paleomagnetic and potassium argon age determinations of the Laschamp geomagnetic polarity event Earth and Planetary Science Letters 6, (No. 9) 4346.CrossRefGoogle Scholar
Carmichael, I.S.E., Nicholls, J. (1967). Iron-titanium oxides and oxygen fugacities in volcanic rocks Journal of Geophysical Research 72 46654687.CrossRefGoogle Scholar
Denham, C.R. Cox, A. (1970). Palaeomagnetic evidence that the Laschamp polarity event did not occur between 30,000 and 12,000 years ago Eos 51 745.Google Scholar
Haggerty, S.E., Lindsley, D.L. (1970). Stability of the pseudobrookite (Fe2TiO5)-ferropseudobrookite (FeTi2O5) series Annual Report of the Director of the Geophysical Laboratory 63 247249.Google Scholar
Haigh, G. (1957). The effect of added titanium and aluminum on the magnetic behaviour of α ferric oxide The Philosophical Magazine Ser. 8, 2, No. 16, pp. 505520.Google Scholar
Kaye, G. (1962). The effect of titanium on the low temperature transition in natural crystals of hematite Proceedings of the Physical Society 80 238243.Google Scholar
Kobayashi, K. Campbell, M.D. Moorhead, J.B. (1965). Size dependence of low temperature change in remanent magnetization of Fe3O4 Annual Progress Report of Rock Magnetism Research Group in Japanpp. 3550.Google Scholar
Lowrie, W., Fuller, M. (1971). On the alternating field demagnetization characteristics of multidomain thermoremanent magnetization in magnetite Journal of Geophysical Research 76, 63396349.Google Scholar
Morin, F.J. (1950). Magnetic susceptibility of αFe2O3 and αFe2O3 with added titanium The Physical Review 78 Ser. 2, No. 6 819820.CrossRefGoogle Scholar
Nagata, T. (1965). Low temperature characteristics of rock magnetism Journal of Geomagnetism and Geoelectricity 17 315324.CrossRefGoogle Scholar
Otteman, J., Frenzel, G. (1965). Der Chemismus des Pseudobrookits von Vulkaniten Schweizerische Mineralogische und Petrographische Mitteilungen 45 819836.Google Scholar
Schull, C.G., Strauser, W.A. Wollen, E.O. (1951). Neutron diffraction by paramagnetic and antiferromagnetic substances The Physical Review 83 333345.Google Scholar
Thellier, E., Thellier, O. (1959). Sur l’intensité du champ Magnétique terrestre dans le passé historique et géologique Annales de Géophysique 15 285376.Google Scholar
Wright, J.B., Lovering, J.F. (1965). Electron-probe microanalysis of the iron-titanium oxides in some New Zealand ironsands Mineralogical Magazine 35 604621.CrossRefGoogle Scholar