1 D18. Recent Advances in Paleoclimatology/Paleoceanography

Sunday, 9 October 2022
8:00 AM - 12:00 PM
503

ASTRONOMICALLY INFLUENCED MILLENNIAL-SCALE CYCLICITY OF THE ANTARCTIC CRYOSPHERE DURING THE EARLY MIOCENE

Paper number: 1-7
Program: Technical Sessions
Time: 9:35 AM – 9:50 AM

Authors

Abstract

Millennial-scale ice sheet variability shorter than precession (1-15 kyr periods) is well-documented in the Pleistocene, providing insight into critical atmosphere-ocean-cryosphere interactions that can inform the mechanism and pace of future climate change. Similar variability is comparatively less established and understood in the Miocene, where higher atmospheric pCO2 and warmer climates prevailed, and continental scale ice sheets were largely restricted to Antarctica.

In this study we evaluate a high-resolution clast abundance dataset representing ice rafted debris, from an early Miocene succession of clastic mudstone at ANDRILL 2A – a proximal marine depositional environment in the Ross Sea, Antarctica. In addition to preserving a record of precession and eccentricity variability in clast abundance, the sedimentation rates are of appropriate resolution to characterize the signature of robust, sub-precessional cyclicity. A particularly strong semi-precession-scale (~10 kyr) cyclicity is observed, with an amplitude modulation in lockstep with eccentricity, indicating a relationship between high frequency Antarctic Ice Sheet dynamics and astronomical forcing.

Bicoherence analysis indicates that many of the observed millennial-scale cycles (as short as 1.2 kyr) are associated with non-linear interactions (combination or difference tones) between each other and the Milankovitch cycles. The presence of these Pleistocene-like cycles during the Miocene reveals the ubiquity of millennial-scale ice sheet variability, even at times when large ice sheets were generally restricted to the Southern Hemisphere.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-383483

© Copyright 2022 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.