Oceanic circulation changes during early Pliocene marine ice-sheet instability in Wilkes Land, East Antarctica

Melissa A. Hansen, Sandra Passchier

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)

Abstract

In the Southern Ocean, unconstrained Westerlies allow for intense mixing between deep waters and the atmosphere. How this system interacts with Antarctic ice sheets and the global ocean circulation is poorly understood due to a paucity of data. The poor abundance and preservation of foraminiferal carbonate in ice-proximal sediments is a major challenge in high-latitude paleoceanography. A new approach is to examine a sediment geochemical record of changing paleoproductivity and sediment redox environment that can be tied to changes in water mass properties. This study focuses on the paleoceanography of the George V Land margin between ~4.7 and 4.3 Ma. This interval at the onset of the early Pliocene Climatic Optimum was characterized by the highest global sea surface temperatures and the lowest sea ice concentrations in East Antarctica in the past 5 million years. At IODP Site U1359, an abrupt increase in Mn/Al ratios ~4.6 Ma indicates an episode of oxic bottom conditions resulting from enhanced wind-driven downwelling of Antarctic surface water. Above, extremely high concentrations of sedimentary barite (Ba excess >40,000 ppm) point to biogenic barite deposition, preservation, and concentration through enhanced upwelling of nutrient-rich Circumpolar Deep Water (CDW). Incursion of CDW onto the continental shelf affected ice discharge and resulted in a stable but reduced ice-sheet configuration over several glacial cycles. The geochemical results along with previous work on Site U1359 for the first time link paleoceanography and cryospheric change based on data from the same high-latitude site.

Original languageEnglish
Pages (from-to)207-213
Number of pages7
JournalGeo-Marine Letters
Volume37
Issue number3
DOIs
StatePublished - 1 Jun 2017

Fingerprint

paleoceanography
oceanic circulation
Ice
ice sheet
Pliocene
deep water
barite
Barite
Sediments
sediment
ice
paleoproductivity
Water
Hypsithermal
downwelling
global ocean
water mass
Sea ice
sea ice
continental shelf

Cite this

@article{3308966155d84358a30024d669ae7885,
title = "Oceanic circulation changes during early Pliocene marine ice-sheet instability in Wilkes Land, East Antarctica",
abstract = "In the Southern Ocean, unconstrained Westerlies allow for intense mixing between deep waters and the atmosphere. How this system interacts with Antarctic ice sheets and the global ocean circulation is poorly understood due to a paucity of data. The poor abundance and preservation of foraminiferal carbonate in ice-proximal sediments is a major challenge in high-latitude paleoceanography. A new approach is to examine a sediment geochemical record of changing paleoproductivity and sediment redox environment that can be tied to changes in water mass properties. This study focuses on the paleoceanography of the George V Land margin between ~4.7 and 4.3 Ma. This interval at the onset of the early Pliocene Climatic Optimum was characterized by the highest global sea surface temperatures and the lowest sea ice concentrations in East Antarctica in the past 5 million years. At IODP Site U1359, an abrupt increase in Mn/Al ratios ~4.6 Ma indicates an episode of oxic bottom conditions resulting from enhanced wind-driven downwelling of Antarctic surface water. Above, extremely high concentrations of sedimentary barite (Ba excess >40,000 ppm) point to biogenic barite deposition, preservation, and concentration through enhanced upwelling of nutrient-rich Circumpolar Deep Water (CDW). Incursion of CDW onto the continental shelf affected ice discharge and resulted in a stable but reduced ice-sheet configuration over several glacial cycles. The geochemical results along with previous work on Site U1359 for the first time link paleoceanography and cryospheric change based on data from the same high-latitude site.",
author = "Hansen, {Melissa A.} and Sandra Passchier",
year = "2017",
month = "6",
day = "1",
doi = "10.1007/s00367-016-0489-8",
language = "English",
volume = "37",
pages = "207--213",
journal = "Geo-Marine Letters",
issn = "0276-0460",
publisher = "Springer Verlag",
number = "3",

}

Oceanic circulation changes during early Pliocene marine ice-sheet instability in Wilkes Land, East Antarctica. / Hansen, Melissa A.; Passchier, Sandra.

In: Geo-Marine Letters, Vol. 37, No. 3, 01.06.2017, p. 207-213.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Oceanic circulation changes during early Pliocene marine ice-sheet instability in Wilkes Land, East Antarctica

AU - Hansen, Melissa A.

AU - Passchier, Sandra

PY - 2017/6/1

Y1 - 2017/6/1

N2 - In the Southern Ocean, unconstrained Westerlies allow for intense mixing between deep waters and the atmosphere. How this system interacts with Antarctic ice sheets and the global ocean circulation is poorly understood due to a paucity of data. The poor abundance and preservation of foraminiferal carbonate in ice-proximal sediments is a major challenge in high-latitude paleoceanography. A new approach is to examine a sediment geochemical record of changing paleoproductivity and sediment redox environment that can be tied to changes in water mass properties. This study focuses on the paleoceanography of the George V Land margin between ~4.7 and 4.3 Ma. This interval at the onset of the early Pliocene Climatic Optimum was characterized by the highest global sea surface temperatures and the lowest sea ice concentrations in East Antarctica in the past 5 million years. At IODP Site U1359, an abrupt increase in Mn/Al ratios ~4.6 Ma indicates an episode of oxic bottom conditions resulting from enhanced wind-driven downwelling of Antarctic surface water. Above, extremely high concentrations of sedimentary barite (Ba excess >40,000 ppm) point to biogenic barite deposition, preservation, and concentration through enhanced upwelling of nutrient-rich Circumpolar Deep Water (CDW). Incursion of CDW onto the continental shelf affected ice discharge and resulted in a stable but reduced ice-sheet configuration over several glacial cycles. The geochemical results along with previous work on Site U1359 for the first time link paleoceanography and cryospheric change based on data from the same high-latitude site.

AB - In the Southern Ocean, unconstrained Westerlies allow for intense mixing between deep waters and the atmosphere. How this system interacts with Antarctic ice sheets and the global ocean circulation is poorly understood due to a paucity of data. The poor abundance and preservation of foraminiferal carbonate in ice-proximal sediments is a major challenge in high-latitude paleoceanography. A new approach is to examine a sediment geochemical record of changing paleoproductivity and sediment redox environment that can be tied to changes in water mass properties. This study focuses on the paleoceanography of the George V Land margin between ~4.7 and 4.3 Ma. This interval at the onset of the early Pliocene Climatic Optimum was characterized by the highest global sea surface temperatures and the lowest sea ice concentrations in East Antarctica in the past 5 million years. At IODP Site U1359, an abrupt increase in Mn/Al ratios ~4.6 Ma indicates an episode of oxic bottom conditions resulting from enhanced wind-driven downwelling of Antarctic surface water. Above, extremely high concentrations of sedimentary barite (Ba excess >40,000 ppm) point to biogenic barite deposition, preservation, and concentration through enhanced upwelling of nutrient-rich Circumpolar Deep Water (CDW). Incursion of CDW onto the continental shelf affected ice discharge and resulted in a stable but reduced ice-sheet configuration over several glacial cycles. The geochemical results along with previous work on Site U1359 for the first time link paleoceanography and cryospheric change based on data from the same high-latitude site.

UR - http://www.scopus.com/inward/record.url?scp=85002170092&partnerID=8YFLogxK

U2 - 10.1007/s00367-016-0489-8

DO - 10.1007/s00367-016-0489-8

M3 - Article

VL - 37

SP - 207

EP - 213

JO - Geo-Marine Letters

JF - Geo-Marine Letters

SN - 0276-0460

IS - 3

ER -