An interglacial on snowball Earth? Dynamic ice behaviour revealed in the Chuos Formation, Namibia

Daniel P. Le Heron*, Marie E. Busfield, Fred Kamona

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Citations (SciVal)
140 Downloads (Pure)

Abstract

The Sturtian is the oldest (ca 716 Ma) of three pan‐global glaciations in the Cryogenian. At Omutirapo, in northern Namibia, a 2 km wide, 400 m deep palaeovalley is filled by glaciogenic strata of the Chuos Formation, which represents the Sturtian glacial record. Sedimentary logging of an exceptionally high‐quality exposure permits detailed stratigraphic descriptions and interpretations, allowing two glacial cycles to be identified. At the base of the exposed succession, strong evidence supporting glaciation includes diamictites, ice‐rafted dropstones and intensely sheared zones of interpreted subglacial origin. These facies collectively represent ice‐proximal to ice‐rafted deposits. Upsection, dropstone‐free mudstones in the middle of the succession, and the absence of diamictites, imply sedimentation free from glacial influence. However, the reappearance of glacial deposits above indicates a phase of Sturtian glacial re‐advance. Comparison with age‐equivalent strata in South Australia, where evidence for sea‐ice free sedimentation has been established previously, suggests that a Sturtian interglacial may have been extensive, implying global‐scale waxing and waning of ice sheets during a Cryogenian glacial event.
Original languageEnglish
Pages (from-to)411-427
Number of pages17
JournalSedimentology
Volume60
Issue number2
Early online date02 Aug 2012
DOIs
Publication statusPublished - 01 Feb 2013
Externally publishedYes

Keywords

  • Cryogenian
  • Glacial
  • Namibia
  • Neoproterozoic
  • Sturtian

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