Spectral Analysis of Physical Property Periodicities in Fine-Grained Sediments from the CRP-3 Drillhole, Ross Sea, Antarctica

F. Florindo^1,2, M. Claps³, F. Niessen⁴ & J. Dinarès-Turell¹

¹Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, 605, I-00143 Rome - Italy
²School of Ocean and Earth Science, University of Southampton, Southampton Oceanography Centre, European Way, Southampton, SO14 3ZH - UK
³AGIP KCO, Coenstraat 7, 2595 WP, Den Haag - The Netherlands
⁴Alfred Wegener Institute for Polar and Marine Research, P.O. Box 20161, D-27515 Bremerhaven - Germany

Received 8 January 2001; accepted in revised form 8 May 2003
 

Abstract - An unexpectedly thick sequence of late Eocene-early Oligocene glaciomarine sediments was recovered in the upper 823 m of the CRP-3 drill-hole. Below this depth, sandstones of the Devonian Beacon Supergroup were recovered down to 939.42 meters below sea floor. We applied spectral analysis techniques to short arrays of physical property data (low-field magnetic susceptibility and wet bulk density) from the CRP-3 core to search for periodicities in selected fine-grained intervals. In the investigated intervals, physical property data clearly revealed the existence of a regular and strong cyclic signal that allow us to discard a stochastic mechanism as controlling these fluctuations. Maximum Entropy, Blackman-Tukey and the Continuous Wavelet Transform (CWT) technique were used to process the two data series. The results show the presence of stable and notable frequencies that suggest the existence of a deterministic external forcing in controlling the deposition of these lithological units. The ratio of these periodicities correspond to those associated with Milankovitch orbital perturbations and, consequently, provide evidence for an external forcing mechanism driving the dynamics of the Early Oligocene East Antarctic Ice Sheet, during early stages of its development.
 

*Corresponding author (florindo@ingv.it)