Two from Donegal: Neoproterozoic glaciogenic episodes on the northeast margin of Laurentia

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47 Citations (Scopus)

Abstract

Two glacial episodes, the Sturtian (ca. 720 Ma) and Marinoan-Varangerian (ca, 590 Ma), characterize many Neoproterozoic successions worldwide. In contrast, northeast Laurentia is typically considered as containing only the latter; in Scotland and Ireland this is represented by the Port Askaig Tillite. Here we present evidence (ice-rafted debris) for a second, younger Neoproterozoic glacial event in the Dalradian Southern Highland Group of Donegal, Ireland. These deposits overlie strata correlative to ca. 595 Ma rocks in Scotland, making this heretofore unrecognized glacial episode a Marinoan-Varangerian equivalent. In that the Port Askaig occurs similar to 3-5 km stratigraphically below the Southern Highland Group rocks, it is most likely Sturtian, not Marinoan-Varangerian, in age. Thus, the Dalradian succession in the Irish Caledonides contains strata representing both the Sturtian and Marinoan-Varanger glaciations.

Original languageEnglish
Pages (from-to)951-954
Number of pages4
JournalGeology
Volume28
Publication statusPublished - Oct 2000

Keywords

  • Neoproterozoic
  • glaciation
  • Dalradian
  • Laurentia
  • LOW-LATITUDE GLACIATION
  • DALRADIAN SUPERGROUP
  • MACKENZIE MOUNTAINS
  • NORTHWESTERN CANADA
  • U-PB
  • SCOTLAND
  • EVOLUTION
  • SEDIMENTATION
  • DEPOSITS
  • EARTH

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