TRACING ENVIRONMENTAL SIGNALS FROM SOURCE TO SINK: ZIRCON (U-TH)/(HE-PB) DOUBLE DATING APPLIED TO FORELAND BASIN FILL OF THE SOUTH CENTRAL PYRENEES, SPAIN

The South Central Pyrenean foreland basin system provides an opportunity to investigate sedimentary processes in response to orogenesis during periods of high climatic and eustatic variability. Continuous outcrop exposure allows for investigation of source to sink processes, from fluvial to deep-water environments at high temporal and spatial resolution. Our new data provide insights into the paleogeography of the Pyrenees during the Eocene and how foreland basin source to sink systems respond to climate/tectonic perturbations. The primary aim of this study is to compare detrital zircon (DZ) analyses from the Ripoll, Ager, Tremp-Gras, Ainsa, and Jaca Basins to investigate changes in sediment provenance in response to tectonic and climatic events. The secondary aim of this study is to compare the DZ U-Pb and (U-Th)/He distributions from multiple stratigraphic levels in the South Central Pyrenean foreland basins to investigate how tectonic-induced variations in sediment supply are propagated from fluvial to deep marine and result in the observed stratigraphy. To achieve this we focused on the Eocene Castissent, Guell (lowest Campanue Fm), and Castigaleau sequences, due to their lateral traceability from fluvial to deep marine. U-Pb results indicate that the main sediment source regions were located in the Eastern Pyrenees, Catalan Coastal Ranges and potentially the Ebro Massif from onset of orogenesis through the Eocene. Sediment was delivered via a braided fluvial network flowing parallel to the emergent Pyrenean thrust front into a shallow and deep-marine environment. Results indicate additional sediment contribution from smaller, more restrictive catchments on emergent fold thrust structures (i.e. Montsec thrust). Different DZ signatures from Eocene deposits in the Tremp-Gras basin and Ager basin indicate unique sediment sources suggesting that the Montsec was a topographic barrier between these basins. Axis parallel flow in the Ager and Tremp-Gras systems brought sediment from their respective sources downstream to the west where rivers met and mixed in the area of the Montsec-Peña Montanesa lateral ramp before flowing down submarine canyons into the deep marine basin floor. Our data allow linkage of hinterland and fold thrust belt evolution to the delivery of sediment to the foreland basin.