Detrital zircon geochronology and provenance of the Torridonian, NW Scotland

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doi: 10.1144/jgs.158.1.15
Authors:Rainbird, Robert H.; Hamilton, Michael A.; Young, Grant M.
Author Affiliations:Primary:
Geological Survey of Canada, Ottawa, ON, Canada
Other:
University of Western Ontario, Canada
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, Vol.158(Part 1), p.15-27. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2001
Note:In English. 64 refs.; illus., incl. 1 table, geol. sketch maps
Summary:Between 30 and 50 single detrital zircons from each of four specimens of the Stoer Group and two specimens from the unconformably overlying Torridon Group were analysed on the GSC SHRIMP II ion probe. 207Pb/206Pb ages of zircons from the Stoer Group range between 3.00 and 1.74 Ga with 95% concentrated between 2.93 and 2.48 Ga. The Bay of Stoer Formation has a small mode c. 2.55 Ga, matching overgrowth ages on some older grains. A few grains between 1.92 and 1.74 Ga occur in each of the Stoer Group specimens. These data are consistent with conventional provenance information and sedimentology, which indicate that the bulk of the Stoer Group probably was derived from local basement of the Lewisian Gneiss Complex and that deposition occurred adjacent to basin-margin growth faults. The two Torridon Group samples have similar detrital zircon age profiles with distinctive modes at 1.80 Ga, 1.66 Ga and 1.10 Ga, interpreted to represent sources of Ketilidian, Labradorian and Grenvillian affinity, respectively. A less well defined cluster c. 2.85-2.55 Ga reflects reworking of the underlying Stoer Group and possibly direct contribution from the Lewisian Gneiss Complex. The youngest concordant detrital zircon yields a maximum age of 1060±18 Ma for the Torridon Group (Applecross Formation). Our data, together with palaeocurrents from the Applecross Formation, suggest that the Torridon Group could have been deposited by a late to post-Grenvillian intermontane or foreland trunk river system flowing northeasterly, parallel to the Grenvillian orogenic belt.
Sections:Petrology
Subsections:Sedimentary petrology
Subjects:Absolute age; Accuracy; Cathodoluminescence; Chronology; Dates; Ion probe data; Mass spectra; Metamorphic rocks; Metasedimentary rocks; Neoproterozoic; Pb/Pb; Precambrian; Proterozoic; Provenance; SEM data; SHRIMP data; Spectra; Torridonian; Upper Precambrian; Europe; Great Britain; Scotland; United Kingdom; Western Europe; Northwestern Scotland; Stoer Group; Torridon Group
Coordinates:N570000 N583000 W0050000 W0060000
Abstract Numbers:01M/2226
Record ID:2001012699
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
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