Orbital forced frequencies in the 975 000 year pollen record from Tenagi Philippon (Greece) |
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| Authors: | H J P M Mommersteeg M F Loutre R Young T A Wijmstra H Hooghiemstra |
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| Institution: | (1) The Netherlands Centre for Geo-Ecological Research (ICG), Hugo de Vries Laboratory, Department of Palynology and Paleo/Actuo-Ecology, University of Amsterdam, Kruislaan 318, NL-1098 SM Amsterdam, Netherlands;(2) Institut d'Astronomie et de Géophysique Georges Lemaitre, University Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve, Belgium |
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| Abstract: | Frequency analysis was applied to different time series obtained from the 975 ka pollen record of Tenagi Philippon (Macedonia, Greece). These time series are characteristic of different vegetation types related to specific climatic conditions. Time control of the 196 m deep core was based on 11 finite 14C dates in the upper 17 m, magnetostratigraphy and correlation with the marine oxygen isotope stratigraphy. Maximum entropy spectrum analyses and thomson multitaper spectrum analysis were applied using the complete time series. Periods of 95–99, 40–45, 24.0–25.5 and 19–21 ka which can be related to orbital forcing, as well as periods of about 68, 30 ka and of about 15.5, 13.5, 12 and 10.5 ka were detected. The detected periods of about 68, 30 ka and 16, 14, 12, 10.5 ka are likely to be harmonics and combination tones of the periods related to orbital forcing. The period of around 30 ka is possibly a secondary peak of obliquity. To study the stability of the detected periods through time, analysis with a moving window was employed. Signals in the eccentricity band were detected clearly during the last 650 ka. In the precession band, detected periods of about 24 ka show an increase in amplitude during the last 650 ka. The evolution of orbital frequencies during the last 1.0 Ma is in general agreement with the results of other marine and continental time series. Time series related to different climatic settings showed a different response to orbital forcing. Time series of vegetational elements sensitive to changes in net precipitation were forced in the precession and obliquity bands. changes in precession caused changes in the monsoon system, which indirectly had a strong influence on the climatic history of Greece. Time series of vegetational elements which are more indicative of changes in annual temperature are forced in the eccentricity band. |
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