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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:41 |
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Conference: Bucharest University Faculty of Physics 2004 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Improved astronomical time scale for the Mircea-Vodã loess-paleosol section
Authors:
C. Necula1, C. Panaiotu*, C.E. Panaiotu**, A. Grama2
Affiliation:
* Univeristy of Bucharest, Faculty of Physics.
** University of Bucharest, Faculty of Geology and Geophysics.
E-mail
Keywords:
paleosol,magnetic susceptibility, coercive force, astronomical dating
Abstract:
In the Mircea Voda loess-paleosol profile we have measured various magnetic parameters. The goal of this work is to refine the time scale for this loess-paleosol sections scale using different magnetic parameters to orbital tuning. We have focused on magnetic susceptibility and coercive force. The first one its a concentration dependent parameter and the second one is independent of the concentration of magnetic minerals. First, we have constructed a time series for susceptibility by correlation with the following target curves: variation of insolation for 15 June , 65ºN and eccentricity. In the spectrum of this time series we have observed the presence of the Milankovich periodicities (100, 40, 23, 19 ka), the signal being strongly affected by red noise. By filtering the signal, it is possible to obtain the four frequencies with better confidence level. In the Lomb-Scargle spectrum , this time series of susceptibility don’t show very clear the Milankovich periodicities, the last two of these (23 and 19ka) being masked by noise. Second, we have constructed a time series for coercive force using the time scale obtained for susceptibility. The Lomb Scargle spectrum displays better the Milankovich periodicities than for magnetic susceptibility. Third, we have constructed a time series for coercive force in a similar way as for the susceptibility. Analyzing the spectrum we have observed that all of four Milankovich periodicities appear with a better confidence level. We will discuss how it is possible to combine these time series based on different magnetic parameters to obtain an improved astronomical dating for the section.
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