Carvallo, C. et al. (2010): Self-reversal of magnetization in oceanic submarine basalts studied with XMCD

Leg/Site/Hole:
ODP 197
ODP 197 1206
Identifier:
2011-071274
georefid

10.1029/2010GL043390
doi

Creator:
Carvallo, C.
Universite Pierre et Marie Curie, Institute de Mineralogie et de Physique des Milieux Condenses, Paris, France
author

Sainctavit, P.
University of Minnesota-Twin Cities, United States
author

Arrio, M. A.
European Synchrotron Radiation Facility, France
author

Guyodo, Y.
author

Penn, R. L.
author

Forsberg, B.
author

Rogalev, A.
author

Wilhelm, F.
author

Smekhova, A.
author

Identification:
Self-reversal of magnetization in oceanic submarine basalts studied with XMCD
2010
Geophysical Research Letters
American Geophysical Union, Washington, DC, United States
37
11
In oceanic basalts, self-reversal of magnetization can be produced during extreme low-temperature oxidation of titanomagnetite by ionic reordering, which leads to Neel N-type magnetism. Titanomaghemites showing N-type reversal below room temperature were found in submarine basalts recovered during Ocean Drilling Program (ODP) Leg 197. In order to better understand the mechanism of self-reversal, we carried out X-ray magnetic circular dichroism (XMCD) at Fe K-edge at room temperature and low-temperature on such a titanomaghemite sample as well as on pure magnetite and maghemite samples. We found that the XMCD spectrum of the N-type titanomaghemite at 20 K is a mirror image of the XMCD spectrum at 300 K, which shows that the octahedral and tetrahedral subnetworks reverse in this process. Ligand-field multiplet calculations of XMCD at Fe K-edge help identify the contributions of the different elements in the measured XMCD spectra. This mechanism could also cause self-reversal above room temperature, which has important consequences for the reliability of paleomagnetic measurements.
Coverage:Geographic coordinates:
North:34.5600
West:172.0900East: 172.0900
South:34.5600

Solid-earth geophysics; Mineralogy of non-silicates; basalts; crystal chemistry; Emperor Seamounts; ferric iron; ferrous iron; igneous rocks; iron; Leg 197; metals; mid-ocean ridge basalts; North Pacific; Northwest Pacific; Ocean Drilling Program; ODP Site 1206; oxides; Pacific Ocean; paleomagnetism; reversals; self-reversal of magnetization; spectra; titanomaghemite; volcanic rocks; West Pacific; X-ray magnetic circular dichroism; X-ray spectra; XANES spectra; XMCD spectra;

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