Origin of the middle Pleistocene transition by ice sheet erosion of regolith

Peter U. Clark, David Pollard

Research output: Contribution to journalArticle

197 Citations (Scopus)

Abstract

The transition in the middle Pleistocene (∼0.9 Ma) seen in δ 18 O deep-sea-core records from relatively lowamplitude, high-frequency (41 kyr) to high-amplitude, low-frequency (100 kyr) ice volume variations under essentially the same orbital forcing can be attributed to a change from an all soft-bedded to a mixed hard-soft bedded Laurentide ice sheet through glacial erosion of a thick regolith and resulting exposure of unweathered crystalline bedrock. A one-dimensional ice sheet and bedrock model which includes transport of sediment and ice by subglacial sediment deformation demonstrates that a widespread deforming sediment layer maintains thin ice sheets before the transition which respond lineary to the dominant (23 and 41 kyr) orbital forcing. Progressive removal of the sediment layer eventually causes a transition to thicker ice sheets whose dominant timescale of change (100 kyr) reflects nonlinear déglaciation processes. In model simulations over the last 3 Ma initialized with no ice and a uniform 50 m sediment layer the time series of ice volume and extent agree in several important aspects with the observed records.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalPaleoceanography
Volume13
Issue number1
DOIs
StatePublished - Feb 1 1998

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sheet erosion
regolith
ice sheet
Pleistocene
ice
orbital forcing
sediment
bedrock
glacial erosion
Laurentide Ice Sheet
deep sea
time series
timescale
simulation

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Palaeontology

Cite this

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Origin of the middle Pleistocene transition by ice sheet erosion of regolith. / Clark, Peter U.; Pollard, David.

In: Paleoceanography, Vol. 13, No. 1, 01.02.1998, p. 1-9.

Research output: Contribution to journalArticle

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