DETRITAL-ZIRCON U-PB AND (U-TH)/HE DOUBLE-DATING PROVENANCE SIGNATURES IN THE JACA FORELAND BASIN: INTERPLAY OF DIRECT VS. RECYCLED SOURCES DURING PYRENEAN OROGENIC GROWTH

Abstract

The Eocene to Miocene clastic wedge of the south Pyrenean basin constitutes a reference model to understand the progressive evolution of sediment provenance and source-to-sink dynamics in a foreland basin. We present new detrital-zircon (DZ) U-Pb and U-Pb-He (ZHe) double-dating data from the Jaca basin and the Ebro basin, providing insights into the evolution of the sedimentary systems that record a major tectonic and drainage reorganization from the late Eocene to Miocene. Three distinct DZ U-Pb signatures have been identified: i) Variscan dominated, ii) mixed Cadomian–Variscan, iii) Cadomian dominated, and two DZ ZHe signatures: i) Pyrenean dominated, ii) pre-Pyrenean dominated. Coupling DZ U-Pb, ZHe, and petrographic data allows us to discriminate among distinct Pyrenean sources as well as to understand how DZ signatures are propagated in a source-to-sink system. Our results indicate that while the eastern Jaca basin was fed from eastern source areas located in the central and eastern Pyrenees, the western Jaca basin was fed from the Basque massifs and the Urbasa–Andía Sierra (Basque–Cantabrian Pyrenees).