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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:32 |
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Conference: Bucharest University Faculty of Physics 2005 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Paleointensity of geomagnetic field from the Apuseni Mountains during the Upper Cretaceous
Authors:
Aneta Nedelcu, Cristian Panaiotu*, Cristina Panaiotu
Affiliation:
*University of Bucharest, Faculty of Phisics
**University of Bucharest, Faculty Geology and Geophysics
E-mail
panaiotu@geo.edu.ro
Keywords:
paleointensity, chemical alteration, Apuseni Mountains
Abstract:
Earth¡¯s magnetic field is one of the most intriguing features of our planet, and because it is a vector quantity it must be described by direction and intensity. In a previous study we recovered paleodirections from magnetic rocks, collected from the Apuseni Mountains. Following this we focused on recovering paleointensities from the same set of magnetic rocks, so as we be able to fully characterize the Upper Cretaceous geomagnetic field.
We have analyzed sixteen samples, according to Thellier-modified Coe and pseudo-Thellier methods. We obtained high and low paleointensity values but because of the relative large difference between these values, we performed some investigations in order to discriminate which are representative for the Upper Cretaceous period. The resulted magnitudes are correlated with the magnetic minerals which are carrying the magnetic signal. Trying to explain the differences encountered, we did specific rock magnetic studies (like alternating field demagnetization of anhysteretic remanent magnetization and of saturation isothermal remanent magnetization), to identify the magnetic carriers, before and after heating up to 600 ¨¬C. These additional studies sustained our presumptions that a reliable explanation for the differences encountered in the poaleointensity values spectrum is the chemical alteration that could have appeared first during the history of our samples and second as heating was applied to them. It resulted that intensity¡¯s values clustering around 12 ¥́T are characteristic for Earth`s magnetic field during the Upper Cretaceous period.
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