Ice sheet dynamics in the vicinity of the Wilkes subglacial basin during the Pliocene

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Author(s): Cook, C.; van de Flierdt, Tina; Williams, Trevor; Hemming, Sidney R.; Pierce, E. L.; Escutia, C.; González, J. J.; Jimenez-Espejo, F. J.; Mckay, Robert M.; Patterson, Molly O.; Passchier, S.; Tauxe, L.
Integrated Ocean Drilling Program, Expedition 318 Scientists
Author Affiliation(s): Primary:
Imperial College London, Department of Earth Science and Engineering, London, United Kingdom
Columbia University, Lamont-Doherty Earth Observatory, United States
University of Granada, Spain
Victoria University of Wellington, New Zealand
Montclair State University, United States
Scripps Institution of Oceanography, United States
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Pliocene (5.3-2.6 Ma) serves as the most recent geological analogue for sustained climatic warmth, but our understanding of the stability of low lying regions of the East Antarctic Ice Sheet during this time is poor. IODP Expedition 318 Site U1361 is ideally located to reveal ice sheet dynamics in the vicinity of the Wilkes Subglacial Basin. Here we investigate the geochemical provenance of ice-rafted detritus (IRD) and detrital marine sediments from Site U1361 deposited between 5.3 and 2.6 Ma. 40Ar/39Ar ages of IRD hornblende grains (>150µm) reveal three distinct age populations. Present throughout the Pliocene is a 420-560 Ma age population, which corresponds to the Ross Orogeny tectono-metamorphic age that is ubiquitous throughout the northern Transantarctic Mountains and George V Land. Mid Pliocene (3.3 to 3.0 Ma) sediments are additionally characterised by two younger age populations (100-120 Ma and <40Ma). Such young ages are not reported from the continental margin in the vicinity of Site U1361. The 100 to 120 Ma ages match age populations of Cretaceous bedrock outcrops in Marie Byrd Land and modern IRD characteristics off West Antarctica, located >2000km to the east. The very young hornblende grains could have been derived from the McMurdo Volcanics from Northern Victoria Land (NVL) and/or the Western Ross Sea area, located >1000km to the east. It is important to note that the Pliocene IRD composition at Site U1361 contrasts markedly with the modern IRD composition of the local area, which is dominated by material from the nearby Adelie Coast (>1500 Ma age population). The neodymium and strontium isotopic compositions of the <63µm detrital fractions reveal two distinct endmembers. The first has εNd values between -6 and -8 and 87Sr/86Sr values of 0.715-0.719, and the second has εNd values of -11 to -16 and 87Sr/86Sr values of 0.721 to 0.730. Potential candidates for endmembers are various Palaeozoic terrains located to the east of Site U1361. While suitable bedrock signatures are found in Northern Victoria Land and the Transantarctic Mountains, geophysical investigations suggest that the infill of the Wilkes Subglacial Basin could also be a potential endmember for Pliocene sediments at U1361. Overall the provenance signature of IRD hornblende grains and fine grained detrital sediments from IODP Site U1361 offers the first direct evidence on locations of East (and West) Antarctic ice sheet destabilisation throughout the Pliocene, revealing very different ice dynamics compared to today.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Absolute age; Antarctic ice sheet; Antarctica; Ar/Ar; Bedrock; Cenozoic; Cretaceous; Dates; East Antarctic ice sheet; Expedition 318; Glacial geology; IODP Site U1361; Ice sheets; Integrated Ocean Drilling Program; Mesozoic; Neogene; Outcrops; Pliocene; Provenance; Southern Ocean; Tertiary; Transantarctic Mountains; Victoria Land; Wilkes Basin; Wilkes Land
Coordinates: S642434 S642434 E1435312 E1435312
Record ID: 2018032635
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