Provenance shifts and crust recycling in the Devonian foreland basin of the Famatinian Orogen, Argentina: Evidence from coupled UPb and LuHf zircon geochronology

Abstract

The Devonian Gualilán Group of the Argentine Precordillera records the evolution of sediment routing systems along the southwestern margin of Gondwana. This study integrates detrital zircon Usingle bondPb geochronology, Lusingle bondHf isotopic data, and multidimensional scaling (MDS) analysis to constrain sediment provenance and its temporal variability. New Usingle bondPb and Lusingle bondHf data collected from stratigraphic sections spanning the Keidel Horizon and along-strike sectors of the basin complement previously published datasets and provide critical constraints for resolving provenance changes that could not be identified using existing data alone. The results define three statistically distinct groups that reflect shifts in sediment sources between pre-Emsian and Emsian–post-Emsian stages. Pre-Emsian deposits (Group 1) are characterized by heterogeneous detrital zircon age spectra and predominantly evolved εHf(t) signatures, indicating dominant sediment derivation from Gondwanan sources, particularly the Pampean-Brazilian and Famatinian orogenic belts, with subordinate input from Mesoproterozoic crust. In contrast, Emsian–post-Emsian deposits (Group 2) show a marked dominance of Mesoproterozoic zircon populations with juvenile εHf(t) values, consistent with derivation from Laurentian-affinity basement exposed in the Western Pampean Ranges. This provenance shift reflects a major reorganization of sediment routing systems associated with the exhumation of basement highs and the development of a topographic barrier that restricted sediment input from eastern Gondwanan sources. A third group (Group 3), restricted to the northern sector of the basin, displays mixed provenance signatures, reflecting continued contribution from Gondwanan sources together with Mesoproterozoic input. This distinctive provenance signal, together with zircon morphological characteristics, suggests a spatially variable sediment-routing system in the northern sector that may include continued local sediment supply, sediment recycling, and a possible south-to-north axial transport component. This along-strike variability highlights the role of local tectonic controls, including differential uplift and basin compartmentalization, in modulating sediment dispersal. The results indicate that sediment supply to the Gualilán Group evolved through distinct tectono-stratigraphic stages during progressive basin reorganization. The Keidel Horizon is interpreted as a chrono-stratigraphic anchor point in the Devonian Foreland Basin, the provenance shift is consistently recorded above the Keidel Horizon, restricting the provenance shift to post- Pragian-Emsian boundary. Overall, this study demonstrates the value of integrating Usingle bondPb and Lusingle bondHf zircon data with statistical and sedimentological approaches to resolve complex provenance patterns and sediment-routing evolution in foreland basin systems.