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Implications of new geochronological constraints on the Aberfeldy stratiform barite deposits, Scotland, for the depositional continuity and global correlation of the Neoproterozoic Dalradian Supergroup

Moles, N.R.; Selby, D.

Implications of new geochronological constraints on the Aberfeldy stratiform barite deposits, Scotland, for the depositional continuity and global correlation of the Neoproterozoic Dalradian Supergroup Thumbnail


Authors

N.R. Moles



Abstract

The Dalradian Supergroup of largely clastic metasediments in Scotland and Ireland is a well-known record of Neoproterozoic to Cambrian sedimentation on the Laurentian margin. Its apparent long duration, from ∼ 800 to ∼ 500 Ma, has encouraged a search for tectonic breaks and unconformities within the sequence. One suggestion is that a break in sedimentation occurred within the upper part of the Argyll Group, specifically in the Easdale Subgroup. Here we report dates for demonstrably synsedimentary barite mineralization hosted by the Easdale Subgroup Ben Eagach Schist Formation. Bedded pyrite from the Foss and the Ben Eagach–Duntanlich barite deposits, stratigraphically < 100 m apart, yields Re-Os ages of 604.0 ± 7.2 Ma and 612.1 ± 18.6 Ma respectively with two-sigma overlap. These ages are similar to the previously constrained 601 ± 4 Ma Tayvallich Volcanic Formation lying 2–5 km stratigraphically above. The new ages suggest continuous sedimentation through this period and, in combination with existing time markers, increase the likelihood that the basal-Argyll, Port Askaig Formation diamictite represents the Marinoan glaciation rather than the Sturtian glacial episode which may not be represented in the Dalradian sequence. As such, we urge caution in using the Dalradian in global compilations of Neoproterozoic history until further geochronological constraints are obtained for the Cryogenian-Tonian parts of the stratigraphy, which is now a high priority.

Citation

Moles, N., & Selby, D. (2023). Implications of new geochronological constraints on the Aberfeldy stratiform barite deposits, Scotland, for the depositional continuity and global correlation of the Neoproterozoic Dalradian Supergroup. Precambrian Research, 384, Article 106925. https://doi.org/10.1016/j.precamres.2022.106925

Journal Article Type Article
Acceptance Date Nov 23, 2022
Online Publication Date Dec 12, 2022
Publication Date 2023-01
Deposit Date Jan 4, 2023
Publicly Available Date Jan 4, 2023
Journal Precambrian Research
Print ISSN 0301-9268
Electronic ISSN 1872-7433
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 384
Article Number 106925
DOI https://doi.org/10.1016/j.precamres.2022.106925
Public URL https://durham-repository.worktribe.com/output/1182781

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