New Nd and Sr data indicate that two isotopically distinct terrains supplied sediment to the Silesian Pennine Basin. The sources consisted of a northerly-derived fluvial system, which was responsible for much of the detritus during Namurian times, and a second major system which entered at the west and south sides of the basin. This second source, which provided material derived from the former Avalonian/Armorican and Gondwanan terranes, became more influential through the Silesian, so that by Westphalian B/C times, the central parts of the basin were being fed by systems derived from the west and south of the basin. Although the inferred source rocks are petrographically diverse their Nd–Sr signatures are remarkably similar, perhaps due to multicyclic sediment homogenization. The change in provenance may reflect early Variscan tectonic activity to the west of the Pennine Basin.