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Occurrence and significance of Silurian K-bentonite beds at Arisaig, Nova Scotia, eastern Canada

Canadian Journal of Earth Sciences

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Abstract

The most extensive succession of K-bentonite beds known in the Silurian of North America occurs at Arisaig on the northern coast of Nova Scotia. At least 40 ash beds are present in the Llandoverian Ross Brook Formation and at least four in the early Ludlovian McAdam Brook Formation. Most of the beds are thin (<5 cm), but one bed (the Smith Brook K-bentonite bed) in the late Llandoverian crenulata Zone and another (the McAdam Brook K-bentonite bed) in the early Ludlovian nilssoni Zone each reach a thickness of 20 cm. New graptolite collections provide critical information on the biostratigraphic position of the K-bentonite beds in the Ross Brook Formation. Geochemical data show that the Arisaig ash beds represent calc-alkaline magmas from plate margin, subduction-related volcanic vents. Differences in K-bentonite stratigraphie distribution, combined with paleogeographic considerations, suggest that the volcanoes were located much farther to the south in the Iapetus than the source volcanoes of the British - Baltoscandian Llandoverian K-bentonites.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Occurrence and significance of Silurian K-bentonite beds at Arisaig, Nova Scotia, eastern Canada
Series title:
Canadian Journal of Earth Sciences
Volume
34
Issue:
12
Year Published:
1997
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Canadian Journal of Earth Sciences
First page:
1630
Last page:
1643
Number of Pages:
14