Obliquity Dominance in Early Pleistocene Sediments From the Antarctic Zone of the Southern Ocean (Indian Ocean Sector)

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Author(s)Billups, K.
Author(s)Münch, B.
Author(s)Garrioch, I.
Author(s)Bradtmiller, L.
Date Accessioned2024-06-26T19:06:38Z
Date Available2024-06-26T19:06:38Z
Publication Date2024-05-26
DescriptionThis article was originally published in Paleoceanography and Paleoclimatology by AGU. © 2024. American Geophysical Union. All Rights Reserved. The version of record is available at: https://doi.org/10.1029/2024PA004855. This article will be embargoed until 11/26/2024.
AbstractWe constructed a record of percent biogenic silica (opal) accumulation at Ocean Drilling Program Site 745B located in the Indian Ocean sector of the Antarctic Zone of the Southern Ocean. The record spans the majority of the early Pleistocene (1.1–2.6 Ma). Orbital-scale sampling affords a look at the relative importance of obliquity versus precession variability through a time interval that is characterized by obliquity pacing in early Pleistocene δ18O records. Variations in the site's magnetic susceptibility record closely resemble those in the benthic foraminiferal δ18O stack (Lisiecki & Raymo, 2005, https://doi.org/10.1029/2004pa001071) and provide orbital-scale age control. Between 1.1 and 1.8 Ma, obliquity-related 41 kyr spectral peaks dominate with relatively little power at precession periods (23–19 kyr) in all records. Between 1.8 and 2.6 Ma, only the δ18O and magnetic susceptibility data display a distinct 41 kyr peak, while the opal lacks spectral power at any of the orbital periodicities. The lack of more pronounced precession-scale variations in the two proxy records is consistent with observations in foraminiferal δ18O records. A low or absent response to precession in these records appears to be due to environmental control. Lack of orbital forcing in the opal record before 1.8 Ma may reflect both a more southerly location of the polar frontal zone with respect to the site, and thus the site's position outside the region of wind-driven upwelling, and/or upwelling waters undersaturated with respect to silica prior to the establishment of the opal belt at about 2 Ma.
SponsorWe thank the editors for handling the manuscript and Aiden Starr and an anonymous reviewer for constructive reviews that have helped us improve this contribution. Financial support for BM was provided by the School of Marine Science and Policy in the form of a Marian Okie graduate fellowship, a Stavros award for analyses, and a travel award to the Fall 2022 AGU meeting. Additional funding for BM was provided by the German Academic Exchange Service (DAAD). We thank Dr. George Luther at the University of Delaware for use of and help with the spectrophotometer.
CitationBillups, K., Münch, B., Garrioch, I., & Bradtmiller, L. (2024). Obliquity dominance in early Pleistocene sediments from the Antarctic zone of the southern ocean (Indian Ocean sector). Paleoceanography and Paleoclimatology, 39, e2024PA004855. https://doi.org/10.1029/2024PA004855
ISSN2572-4525
URLhttps://udspace.udel.edu/handle/19716/34539
Languageen_US
PublisherPaleoceanography and Paleoclimatology
TitleObliquity Dominance in Early Pleistocene Sediments From the Antarctic Zone of the Southern Ocean (Indian Ocean Sector)
TypeArticle
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