Abstract
We investigated the acquisition of thermochemical remanent magnetization (TCRM) on basaltic rocks from the volcanic island of SAo Tome (Gulf of Guinea) and from the southern part of the Red Sea Rift, both containing homogeneous titanomagnetite grains with Curie temperatures of 100-200 degrees C. The TCRM was created in a rotating thermomagnetometer by cooling the samples from 570 to 200 degrees C at a rate of 1 degrees C/hr in the presence of a laboratory magnetic field of 50 mu T. The TCRM acquisition occurred at high temperature T > 520 degrees C through the nucleation of ilmenite lamellae dividing the titanium-magnetite cells. Mutual Fe-Ti diffusion moved the composition of the cells closer to that of magnetite, leading to an increase in the Curie temperature T-?. The TCRM was formed at practically fixed volume of the titanomagnetite cells when T-? exceeded T. Theory indicates that the TCRM should be very close to the value of a pure thermoremanent magnetization acquired in the same field. The Thellier-style experiments conducted on the samples bearing a laboratory induced TCRM confirmed these predictions, with palaeointensity estimates in agreement to within 5% with expected value. This conclusion radically differs from previous results obtained in the case of a pure chemical remanent magnetization and gives hope that a TCRM could be a robust source of palaeomagnetic information, yielding unbiased palaeointensity determinations.
| Dokumententyp: | Zeitschriftenartikel |
|---|---|
| Fakultät: | Geowissenschaften > Department für Geo- und Umweltwissenschaften |
| Themengebiete: | 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie |
| ISSN: | 2169-9313 |
| Sprache: | Englisch |
| Dokumenten ID: | 84025 |
| Datum der Veröffentlichung auf Open Access LMU: | 15. Dez. 2021, 15:10 |
| Letzte Änderungen: | 15. Dez. 2021, 15:10 |
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