T242 Ice-Sheet and Sea-Ice Paleo-Reconstructions from the Arctic, Antarctica, and the Southern Ocean

Friday, 30 October 2020
10:00 AM - 2:00 PM
Meeting Rooms

NEW MAGNETOSTRATIGRAPHIC INSIGHTS FROM ICEBERG ALLEY ON THE RHYTHMS OF ANTARCTIC CLIMATE DURING THE PLIO-PLEISTOCENE

Paper number: T242-6
Program: Technical Sessions
Time: 11:15 AM – 11:30 AM

Authors

Abstract

International Ocean Discovery Program (IODP) Expedition 382 in the Scotia Sea’s “Iceberg Alley” recovered among the most continuous and highest resolution stratigraphic records in the Southern Ocean near Antarctica spanning the last 3.3 Myr. Sites drilled in Dove Basin (U1536/U1537) have well-resolved magnetostratigraphy and a strong imprint of orbital forcing in their lithostratigraphy. All magnetic reversals of the last 3.3 Myr are identified, providing a robust age model independent of orbital tuning. In this presentation, we discuss the alternation of warmer (diatom-rich) versus cooler (silty clays) Dove Basin lithologies in comparison to the LR04 benthic δ18O stack using an ensemble of possible age models constrained by the magnetic reversals. To account for limitation in the age model resolution, we begin by comparing the amplitude modulation of the eccentricity, obliquity, and precession frequency bands for different age-depth model possibilities. Then we compare the position of the magnetic reversals relative to local facies changes in Dove Basin and the same magnetic reversals relative to benthic δ18O at North Atlantic IODP Site U1308. Finally, to establish a higher resolution age model in the latest Pliocene and early Pleistocene, we explore the possibility of interhemispheric stratigraphic correlation between North Atlantic IODP sites and Dove Basin using Relative Paleointensity (RPI). We demonstrate Dove Basin facies change at different times than benthic δ18O during intervals between ~3-1 Ma. These differences are consistent with precession phase shifts and suggests climate signals with a Southern Hemisphere summer insolation phase were recorded around Antarctica. If Dove Basin lithology reflects local Antarctic ice volume changes, these signals could represent ice sheet precession variations not captured in benthic δ18O during the 41-kyr world.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-358985

© Copyright 2020 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.