Heavy-mineral, mineral-chemical and zircon-age constraints on the provenance of Triassic sandstones from the Devon coast, southern Britain
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Date
2013-05-20
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Wydawnictwo Naukowe UAM
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Abstract
An integrated heavy-mineral, mineral-chemical and zircon-dating study of the Triassic succession exposed on the south
Devon coast, in the western part of the Wessex Basin, indicates derivation from a combination of granitic and metasedi-mentary lithologies of ages of mostly over 550 Ma. These sources were probably located at a relatively proximal location
near the southern margin of the basin. Derivation from more distal sources in the Armorican Massif or local Variscan
sources to the west appears unlikely in view of the scarcity of Permo-Carboniferous (Variscan-age) zircons. The Bud-leigh Salterton Pebble Bed Formation was derived from a different combination of source lithologies than the Otter
Sandstone Formation, the former including staurolite-grade metasediments that were absent in the catchment area of
the Otter Sandstone. The Devon coast succession has provenance characteristics that differ from equivalent sandstones
further east in the Wessex Basin, and from sandstones in the East Irish Sea Basin to the north. These differences indicate
that sediment supply patterns to the linked Triassic basin systems in southern Britain are complex, involving multiple
distinct sub-catchment areas, and that heavy-mineral studies have considerable potential for unravelling these sub-catchment area sources.
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Keywords
Heavy minerals, zircon, provenance, triassic, devon
Citation
Geologos, 2013, vol. 19, 1, pp. 67-85.
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ISBN
978-83-232187-4-6
ISSN
1426-8981