The Neoproterozoic glaciogenic Lillfjället Formation, Southern Swedish Caledonides
2011 (English)In: Geological Record of Neoproterozoic Glaciations / [ed] Arnaud, E; Halverson, GP; Shields Zhou, G, Avon: The Geological Society Publishing House, 2011, 629-634 p.Chapter in book (Refereed)
The Tossasfjallet Group, which crops out in the Middle Allochthon of the Scandinavian Caledonides, contains the glaciogenic Lillfjället Fm. Evidence that supports the interpretation of the Lillfjallet formations as glacially related include the presence of diamictite beds, the presence of lonestones, although few, in laminated units, one possible faceted clast, involution-like deformation structures, and the presence of sandstone wedges cutting 2.5-3m down into two different diamictite beds. Similar to the other glaciogenic formations in southern and central Scandinavia (Moelv and Langmarkberg formations), the Lillfjallet Fm. rests on a unit of peritidal, sabkha-type dolomite of the Storan Fm. Poor exposure contributes to the uncertainty about the thickness of the formation. In this account, the Lillfjallet Fm. stratigraphy has been divided into three subunits: (i) a lower diamictite-dominated unit, (ii) a middle unit composed of distinctly laminated grey sandy mudstone and (iii) an upper diamictite-dominated unit. There is no information available from the Tossasfjallet Group concerning palaeolatitudes and chemostratigraphy. Poor isotopic evidence (Ar-40/Ar-39) from the Ottfjallet Dolerites, which cut the Tossasfjallet Group, indicates that the succession is older than c. 665 Ma, so a reliable correlation with global glaciation events is not yet possible.
Place, publisher, year, edition, pages
Avon: The Geological Society Publishing House, 2011. 629-634 p.
, Geological Society Memoirs, ISSN 0435-4052 ; 36
IdentifiersURN: urn:nbn:se:su:diva-94460DOI: 10.1144/M36.61ISI: 000300897200061ISBN: 978-1-86239-334-9OAI: oai:DiVA.org:su-94460DiVA: diva2:653592