Periglacial evidence for a 1.91–1.89 Ga old glacial period at low latitude, Central Sweden. (18th November 2013)

• Record Type: Journal Article
• Authors: Kuipers, Gerrit; Beunk, Frank F.; van der Wateren, Frederik M.
• Is Part Of: Geology today. Volume 29:Number 6(2013:Nov./Dec.)
• Page Start: 218
• Page End: 221
• Publication Date: 2013-11-18
• Subjects: Geology -- Periodicals; 551
• DOI: 10.1111/gto.12027
• Languages: English
• ISSNs: 0266-6979

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Cryoturbation and slump fold‐like sedimentary structures in ca. 1.9 Ga old dacitic metavolcanic sediments in West Bergslagen, Central Sweden, are recognized as a lowland periglacial environment. This type of environment is comparable with present day tundra in Siberia. Ice‐wedge casts and cryoturbation, together with polygonal frost patterns, are typical geomorphological structures above permafrost in this type of environment. The sedimentary environment could be interpreted as periglacial, broadly comparable to present day tundras. Intensive cryoturbation of the formation and close structural analogy with Quaternary ice‐wedges suggests a cold and humid environment. This discovery is corroborated by a previous report of glacial sediments and structures from NW Australia of ca. 1.8 Ga age. Both occurrences developed at low geographical latitudes, at locations far apart in the Late Palaeoproterozoic supercontinent Columbia. Either suggest the existence of a ca. 100 Ma long epoch of extreme, though possibly intermittent glaciations during the ca. 1.4 Ga long 'Proterozoic gap' (∼2.2–0.77 Ga) from which no convincing glacial deposits were previously known.</p> </abstract>