Extension and clockwise shift of central to western Europe’s drainage across the Permo-Triassic transition

At the southwestern margin of the Central European Basin, continental redbed deposition prevailed for > 10 Myrs from Late Permian to Middle Triassic time. The clastic sedimentary rocks are generally thought to derive from uplands located southwest to southeast of the basin margin, but specific sources and spatiotemporal trends are poorly understood. This study reports U–Pb ages and morphologic data for > 3000 detrital zircon grains from 40 samples from Black Forest, Palatinate Forest, and Northern Vosges. Concordant zircon ages range from ~ 260 Ma to ~ 3.5 Ga with prominent Variscan (30%), Caledonian (23%), and Cadomian (28%) age groups. The age distributions show increasing Cadomian and older U–Pb ages with decreasing stratigraphic age. Early Variscan ages increase up-section relative to late Variscan ages. The prominent ~ 450 Ma age component transitions to discrete ~ 420 Ma and ~ 480 Ma components from late Olenekian time. These trends are independent of zircon grain size. The results reflect the change from mostly local sources in Wuchiapingian time to a significantly enlarged catchment area from late Induan onward. The drainage-basin extension includes a clockwise shift recorded by tapping new catchment areas in the Armorican and London–Brabant massifs. This comes along with a homogenization of sediment composition across the entire drainage and deposition area in late Olenekian-to-early Anisian time. The study serves as an example of zircon-based signatures for regional-scale drainage-basin widening related to relief planation in the aftermath of major orogenic phases and increased sediment flux following major environmental crises. It highlights the relevance of grain-shape parameters in detrital geochronology.