TY - JOUR
T1 - Impact of Eocene-Oligocene Antarctic Glaciation on the Paleoceanography of the Weddell Sea
AU - Hojnacki, Victoria
AU - Lepp, Allison
AU - Horowitz Castaldo, Josie
AU - States, Abbey
AU - Li, Xiaona
AU - Passchier, Sandra
N1 - Publisher Copyright:
© 2022. American Geophysical Union. All Rights Reserved.
PY - 2022/12
Y1 - 2022/12
N2 - The Eocene-Oligocene Transition (EOT) at ∼34 Ma marked a climatic shift from greenhouse to icehouse conditions, toward long-lasting lower global temperatures and a continental ice sheet in the Antarctic. We report on sedimentological and inorganic geochemical results across the EOT at Ocean Drilling Program (ODP) Site 696 in the Weddell Sea, within the Antarctic limb of the Atlantic circulation. The geochemical composition of detrital, authigenic and biogenic marine sediment components, and sortable silt proxies demonstrate the impact of ice growth on high latitude water masses. Sortable silt grain size and Zr/Rb ratios attest to a period of vigorous circulation at ∼36.2–35.8 Ma, coincident with a known warm interval in the Southern Ocean. Across the EOT, detrital provenance suggests that regional ice growth in the western Weddell Sea was stepwise, first expanding in the Antarctic Peninsula, followed by parts of West Antarctica. In conjunction with regional ice growth, high uranium enrichment factors (U EF) in sediments spanning the EOT interval indicate anoxic conditions in the sediment with evidence of carbonate dissolution. Following glacial expansion and sea-ice formation at ∼33.6 Ma, a return to oxic conditions and carbonate preservation is observed with excess barium and phosphorous indicative of an increase in productivity, and potentially carbon export. Our results highlight the important connections between ice growth and the changing properties of high-latitude water masses at the EOT with impacts on the global ocean circulation.
AB - The Eocene-Oligocene Transition (EOT) at ∼34 Ma marked a climatic shift from greenhouse to icehouse conditions, toward long-lasting lower global temperatures and a continental ice sheet in the Antarctic. We report on sedimentological and inorganic geochemical results across the EOT at Ocean Drilling Program (ODP) Site 696 in the Weddell Sea, within the Antarctic limb of the Atlantic circulation. The geochemical composition of detrital, authigenic and biogenic marine sediment components, and sortable silt proxies demonstrate the impact of ice growth on high latitude water masses. Sortable silt grain size and Zr/Rb ratios attest to a period of vigorous circulation at ∼36.2–35.8 Ma, coincident with a known warm interval in the Southern Ocean. Across the EOT, detrital provenance suggests that regional ice growth in the western Weddell Sea was stepwise, first expanding in the Antarctic Peninsula, followed by parts of West Antarctica. In conjunction with regional ice growth, high uranium enrichment factors (U EF) in sediments spanning the EOT interval indicate anoxic conditions in the sediment with evidence of carbonate dissolution. Following glacial expansion and sea-ice formation at ∼33.6 Ma, a return to oxic conditions and carbonate preservation is observed with excess barium and phosphorous indicative of an increase in productivity, and potentially carbon export. Our results highlight the important connections between ice growth and the changing properties of high-latitude water masses at the EOT with impacts on the global ocean circulation.
KW - Antarctica
KW - Eocene
KW - glaciation
KW - paleoceanography
KW - sortable silt
KW - trace element
UR - http://www.scopus.com/inward/record.url?scp=85145182247&partnerID=8YFLogxK
U2 - 10.1029/2022PA004440
DO - 10.1029/2022PA004440
M3 - Article
AN - SCOPUS:85145182247
SN - 2572-4517
VL - 37
JO - Paleoceanography and Paleoclimatology
JF - Paleoceanography and Paleoclimatology
IS - 12
M1 - e2022PA004440
ER -