The 9 km thick Lower Old Red Sandstone succession of the northern part of the Midland Valley Basin, Scotland, ranges from Wenlock to Emsian in age and largely comprises conglomerates in the east passing westwards into sandstones and siltstones. Previously, the depositional and tectonic setting of the basin has been poorly constrained, as has the relationship between sediments of the northern Midland Valley and the Grampian outliers at Aberdeen, Rhynie, Cabrach, Tomintoul and New Aberdour. This study focuses on establishing the stratigraphic framework of the areas and outlining the key controls and source of sedimentation during deposition of the Lower Old Red Sandstone, placing the geological history within the larger Caledonian framework. Sedimentological investigation alongside petrographical point count, heavy mineral and detrital zircon analysis allows the reconstruction of a large distributive fluvial system sourced from the NE within the Caledonian foreland, within which the Lower Old Red Sandstone of the northern Midland Valley Basin was deposited. Sedimentation was continuous across the line of the Highland Boundary Fault. Sedimentation within the Grampian outliers was locally influenced, however facies association development is comparable with the base of the laterally time-equivalent northern Midland Valley Basin stratigraphy. Sedimentary provenance analysis indicates a similar source terrane for the sediments of both areas, with detrital zircon age spectra comparable to those of the Dalradian Supergroup and localised contemporaneous volcanism, with conglomerate clast-size indicating a proximal source. Sedimentation of the Lower Old Red Sandstone of the northern Midland Valley Basin and Grampian outliers is thus attributed to Siluro-Devonian basement uplift in the Caledonian foreland driven by thick-skinned tectonics.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:737952 |
| Date | January 2017 |
| Creators | McKellar, Zoe |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=236193 |
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