Scratching the surfaceFootprint of a late Carboniferous ice sheet

Authors Organisations
  • Daniel Le Heron(Author)
    University of Vienna
  • Pierre Dietrich(Author)
    Université de Rennes 1
  • Marie Busfield(Author)
  • Christoph Kettler(Author)
    University of Vienna
  • Sarah Bermanschlager(Author)
    University of Vienna
  • Bernhard Grasemann(Author)
    University of Vienna
Type Article
Original languageEnglish
JournalGeology
Early online date23 Sep 2019
DOI
Publication statusE-pub ahead of print - 23 Sep 2019
Show download statistics
View graph of relations
Citation formats

Abstract

Field observations in conjunction with aerial images from an unmanned aerial vehicle were used to create the first map of a glacial unconformity underlying the late Carboniferous Dwyka Group of South Africa. Crosscutting relationships reveal that the glacial unconformity at Oorlogskloof, in which flutes, grooves, and striae were ploughed into unconsolidated sand, formed in a three-phased process charting a periodic shift in the locus of subglacial erosion. The unconformity formed by a periodically decoupled ice sheet in a probable tidewater setting. This model contrasts with earlier views that the structures simply record progressive ice-margin liftoff during transgression, and they provide unique insight into the complex temporal development of a 300 Ma subglacial environment.