Abstract

Sediment provenance analysis is important in reconstructing chronological and spatial relationships between source area erosion/exhumation and sediment deposition in adjacent basins. Here we provide new provenance data from conglomerate clast populations, sandstone petrography, heavy mineral assemblages and U–Pb detrital zircon geochronology from the 9 km-thick, Siluro-Devonian Lower Old Red Sandstone (LORS), northern Midland Valley Basin (MVB), Scotland. The MVB developed in the foreland to the Caledonian Orogeny and comprises a mixed succession of conglomerate and pebbly sandstone interbedded with volcanic lithologies. Analysis of 554 samples (137 petrographical thin sections across 22 formations/members; 390 conglomerate clast recordings across 7 locations; 17 heavy mineral and 10 detrital zircon samples) from the entire succession shows a proximal, consistent source or sources located to the east or NE. These results indicate that sediment derived directly from areas of Scandian uplift of Norwegian lithologies is unlikely to have made a significant contribution to the LORS of the northern MVB and the provenance instead lies more proximally in both the neighbouring Dalradian Supergroup metasedimentary rocks and other contemporaneous lithologies. The coarse-grained nature of the sedimentary rocks suggests consistent and continued uplift of these lithologies throughout deposition of the LORS. Integration of these provenance techniques allows robust interpretation of basin fill from a tectonically rejuvenating source in the Caledonian foreland.

Supplementary material: MVB LORS palaeocurrent data; List of sample locations is available at https://doi.org/10.6084/m9.figshare.c.4661966

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