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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:38 |
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Conference: Bucharest University Faculty of Physics 2006 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Testing orbital tuning method for magnetic susceptibility data recorded in Mostistea loess deposit.
Authors:
Cristian Necula, Cristian Panaiotu
Affiliation:
Paleomagnetic Laboratory, University of Bucharest
E-mail
c3necula@yahoo.com
Keywords:
orbital tuning, loess-paleosol, magnetic susceptibility, Milankovich periodicities
Abstract:
We have tested here the orbital tuning method trough generating some time series for magnetic susceptibility derived from Mostistea loess deposit by correlation between susceptibility curve and different target curves, choosing different correlation points, using Match software (Lisiecki&Lisiecki, 2002): 65ºN summer insolation (Berger&Loutre, 1991), stack of 57 globally distributed benthic δ18O records (Lisiecki&Raymo, 2005) and both these curves in the same time. Spectral analysis of the time series obtained by correlation with the insolation curve shows the main Milankovitch periodicities (100, 41, 23 and 19ka) with a significant growth of 41 and 19ka periods and with a period centered at 125ka for correlation without tie points. Thus, taking a number of correlation points, will be induces the 100ka period proving that the proxy-climate records oscillate with this period and it is not induced by orbital tuning. Time series obtained by correlation with the δ18O records display a clearer spectrum dominated by 100 and 41ka periodicities without any of precession periodicities above the confidence level. Correlation with both insolation and benthic oxygen curves incorporate the 23ka precession period too in our time series which testify that the precession periodicities are induced by orbital tuning from insolation. All the time series are more or less in a good agreement with IRSL ages (Panaiotu et al., 2006). Wavelet spectrum of the orbital tuned time series show a break of 41ka oscillations between 75 and 240ka while the matched with δ18O records time series display a continuous band in the last 433.000 years which demonstrate that the choose of target curves affect the dominance of orbital periodicities. The depth-age curves for all time series can by clearly be subdivided into three parts indicating that the source area experienced a series of stepwise expansion and reduction in the late Quaternary.
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