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147882 - New magnetostratigraphic insights from iceberg alley.pdf (9.72 MB)

New magnetostratigraphic insights from Iceberg Alley on the rhythms of Antarctic climate during the Plio-Pleistocene

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posted on 2023-05-21, 04:18 authored by Reilly, BT, Tauxe, L, Brachfeld, S, Raymo, M, Bailey, I, Hemming, S, Weber, ME, Williams, T, Garcia, M, Guitard, M, Martos, YM, Perez, LF, Zheng, X, Linda ArmbrechtLinda Armbrecht, Cardillo, FG, Du, Z, Fauth, G, Glueder, A, Gutjahr, M, Hernandez-Almeida, I, Hoem, FS, Hwang, J-H, Iizuka, M, Kato, Y, Kenlee, B, O'Connell, S, Peck, V, Ronge, TA, Seki, O, Tripathi, S, Warnock, J

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. During the Pleistocene, alternation of terrigenous versus diatomaceous facies shows power in the eccentricity and obliquity frequencies comparable to the amplitude modulation of benthic δ18O records. This suggests that variations in Dove Basin lithostratigraphy during the Pleistocene reflect a similar history as globally integrated ice volume at these frequencies. However, power in the precession frequencies over the entire ∼3.3 Myr record does not match the amplitude modulation of benthic δ18O records, suggesting Dove Basin contains a unique record at these frequencies. Comparing the position of 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, we demonstrate Dove Basin facies change at different times than benthic δ18O during intervals between ∼3 and 1 Ma. These differences are consistent with precession phase shifts and suggest 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-paced variations not captured in benthic δ18O during the 41-kyr world.

History

Publication title

Paleoceanography and Paleoclimatology

Volume

36

Article number

e2020PA003994

Number

e2020PA003994

Pagination

1-27

ISSN

2572-4517

Department/School

Institute for Marine and Antarctic Studies

Publisher

Wiley-Blackwell Publishing Inc.

Place of publication

United States

Rights statement

© 2021. American Geophysical Union.

Repository Status

  • Open

Socio-economic Objectives

Antarctic and Southern Ocean ice dynamics; Antarctic and Southern Ocean oceanic processes

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