Cenozoic Climate and Sea Level History from Glacimarine Strata off the Victoria Land Coast, Cape Roberts Project, Antarctica

  1. Michael J. Hambrey2,
  2. Poul Christoffersen2,3,
  3. Neil F. Glasser2 and
  4. Bryn Hubbard2
  1. P. J. Barrett

Published Online: 24 MAR 2009

DOI: 10.1002/9781444304435.ch15

Glacial Sedimentary Processes and Products

Glacial Sedimentary Processes and Products

How to Cite

Barrett, P. J. (2007) Cenozoic Climate and Sea Level History from Glacimarine Strata off the Victoria Land Coast, Cape Roberts Project, Antarctica, in Glacial Sedimentary Processes and Products (eds M. J. Hambrey, P. Christoffersen, N. F. Glasser and B. Hubbard), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304435.ch15

Editor Information

  1. 2

    Centre for Glaciology, Institute of Geography & Earth Sciences, Aberystwyth University, Wales, Ceredigion SY23 3DB, UK

  2. 3

    Scott Polar Research Institute, University of Cambridge, Lensfield Road, Cambridge, CB2 1ER, UK

Author Information

  1. Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand

Publication History

  1. Published Online: 24 MAR 2009
  2. Published Print: 14 DEC 2007

Book Series:

  1. Special Publication Number 39 of the International Association of Sedimentologists

Book Series Editors:

  1. Isabel Montanez

Series Editor Information

  1. University of California, Davis, USA

ISBN Information

Print ISBN: 9781405183000

Online ISBN: 9781444304435

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Keywords:

  • pre-quaternary glacial systems;
  • Cenozoic climate and sea level history from glacimarine strata off Victoria Land coast, Cape Roberts Project, Antarctica;
  • sedimentary facies – conglomerate, sandstone and mudstone with marine fossils throughout;
  • cyclicity of Cape Roberts section reflecting influence of earth's varying orbital parameters on climate and sea level;
  • seismic stratigraphy of sequence cored off Cape Roberts;
  • glacimarine sediments - varying in texture, composition and sedimentary structures;
  • chronology of CRP Cenozoic section;
  • Conglomerate (uppermost Eocene);
  • Diamicton, muddy sandstone (Pliocene, Quaternary)

Summary

This paper reviews the record of past climate and sea level from 34 to 17 Ma provided by continuous core through 1500 m of shallow marine strata off the Victoria Land coast of Antarctica. The site was selected because it is close to the edge of the East Antarctic Ice Sheet. Previous drilling and seismic surveys had suggested a thick seaward-dipping sequence of Oligocene and older age close to the coast. However, the floor of the basin, lower Devonian sandstone, was encountered beneath uppermost Eocene conglomerate. The strata were deposited in a rift basin just seaward of the Transantarctic Mountains c. 20 m.y. after uplift began. Sediment was delivered by rivers and glaciers both from and behind the mountains from the East Antarctic interior. Sediment accumulation was rapid and the record more complete for the period 34 to 31 m.y., but then slowed as basin subsidence declined, leaving major time gaps, but still a representative record of the entire time span. Basin filling kept pace with subsidence. The sedimentary facies – conglomerate, sandstone and mudstone with marine fossils throughout – are typical of the coastal margin of a subsiding sedimentary basin, with the addition of diamictite beds in the upper 900 m recording marine terminating glaciers that extended periodically beyond the coast. Deposition was characterised by repetitive vertical facies successions of conglomerate and fine sandstone in the lower part of the section and by cyclic facies successions of diamictite, sandstone and mudstone from a few to over 60 m thick in the upper part. These are thought to reflect glacio-eustatic changes in sea level on a wave-dominated coast in concert with advance and retreat of piedmont ice onto the continental shelf, with diamicton and sand (nearshore) grading upwards to mud (shelf) and then to sand (inner shelf to shoreline). Tephra dating of two cycles at 23.98 and 24.22 Ma allows their correlation with 40,000 years cycles in the deep-sea isotope record, and ascribed to eustatic sea-level changes of 30–60 m. This suggests that the cyclicity of the Cape Roberts section reflects the influence of the earth's varying orbital parameters on climate and sea level, with over 50 sedimentary cycles preserved out of the possible 200–400 cycles during this time period. The Cape Roberts section also records a dramatic increase in glacial influence at around 33 Ma, with the proportion of glacial facies ranging from 10 to 30% of the sedimentary section through to 17 Ma. The section also records a progressive shift from chemical to physical weathering (decline in CIA index and increase in % illite-chlorite) from 33 to 25 Ma, and a decline in marine palynomorphs characteristic of fresh melt water mingling over the same interval. The terrestrial pollen record records interglacial climate and indicates this to be cool temperate for the entire period from 34 to 17 Ma though slightly cooler from c. 25 Ma.