Periodicities of CaCO3 cycles in the Pliocene of Sicily: discrepancies with the quasi‐periods of the Earth's orbital cycles?

Publisher Website
Google Scholar
Abstract
A high‐resolution CaCO3 record in combination with a detailed magnetostratigraphy is presented for the rhythmically bedded marly sequence of the Pliocene Trubi Formation on Sicily (Italy).Magnetostratigraphic age calibration and subsequent spectral analysis of the variatrions in CaCO3 content yield a remarkably consistent discrepancy between the resulting periodicities and the corresponding quasi‐periods of the Earth's orbital cycles. This discrepancy can only be explained by assuming that ages assigned to polarity reversal boundaries in the geomagnetic polarity time‐scale lack sufficient precision.A new polarity time‐scale is presented for the major part of the Gilbert and Gauss Chron using the radiometrically dated Gilbert‐Gauss Chron boundary at 3.40 Ma as an age reference point and extrapolating an average quasi‐period of 21.7 kyr of the precession cycle as the periodicity of small‐scale colour annex CaCO3 cycles.