Composition and provenance of sandstones and conglomerates from the Silurian inliers and the Lanark Group, Midland Valley

The tectonic evolution of the Midland Valley of Scotland during the Lower Palaeozoic to Devonian, and its setting within Caledonian orogenic models has been the focus of much recent debate. Central to this debate is the sedimentology, structure and provenance of a sequence of Silurian sedimentary rocks and the overlying Lower Old Red Sandstone (Lanark Group). The Silurian sedimentary sequences are exposed in a number of inliers which occur along the southern margin of the Midland Valley of Scotland. In general, the inliers record a transition from an older Llandovery transgressive marine sequence to a younger regressive terrestrial Lower Wenlock succession. However, there are significant differences in the detailed stratigraphy and thickness of the sequences present within the individual inliers.This variation probably reflects their deposition within in a number of small sub-basins which were developed oblique to the Southern Upland Fault during regional sinistral strike-slip.