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Searching solar periodicities in the late glacial record of atmospheric radiocarbon.

Tomasz Goslar, Laborde Nadine Tisnerat, Martine Paterne

Abstract


Accelerator mass spectrometry radiocarbon (AMS (super 14) C) dating of the late glacial section of laminated sediments from Lake Gosciaz and Lake Perespilno, Poland, performed with time resolution of 20-30 years suggests quasi-periodic oscillations of Delta (super 14) C. The regularity of oscillations has been checked by the Maximum Entropy and Fast Fourier Transform methods (MEM and FFT), which revealed peaks at 200 and 230 yr. These periods are similar to those found in the high-precision Holocene Delta (super 14) C record, and attributed to the changing sun. The analytical assessment of the significance of the FFT and MEM peaks is problematic because of non-uniform spacing and various uncertainties in the input data. The significance of the peaks has therefore been studied by the Monte-Carlo method. Because the original data were approximated with a spline function, the amplitude of the MEM and FFT peaks depends on the stiffness of the spline, which is strongly related to the "real" uncertainty of (super 14) C ages. The Monte-Carlo experiments demonstrate that the significance levels of the MEM and FFT peaks also depend on the spline stiffness. Therefore, the existence of solar (super 14) C variations in the Late Glacial remains an open question.

Keywords


Monte Carlo analysis;Lake Perespilno;late glacial environment;Fourier analysis;periodicity;solar cycles;laminations;lake sediments;Poland;Lake Gosciaz;lacustrine environment;climate change;planar bedding structures;sedimentary structures;statistical analysis;atmosphere;Central Europe;data processing;paleoclimatology;Pleistocene;upper Pleistocene;Europe;sediments;Cenozoic;Quaternary;C 14;carbon;dates;isotopes;radioactive isotopes;absolute age

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