TEMPORAL CONSTRAINTS ON MULTIPLE RIFTING STAGES OF A HYPER-EXTENDED CONTINENTAL MARGIN USING COUPLED BEDROCK AND DETRITAL THERMOCHRONOMETRY, MAULEON BASIN, WESTERN PYRENEES

Multi-mineral double-dating of detrital and bedrock units from a hyper-extended continental margin have the potential to show a detailed progression and timing of continental rifting. Modern thermochronometric dating techniques have a range of applications in quantifying tectonic and sedimentary processes at rifted continental margins. Zircon (U-Th)/He (ZHe) and detrital zircon U-Pb dating, constrain sediment provenance and the temporal and thermal evolution of tectonically active source areas. Additionally, hyper-extended margin basins, such as the Mauléon basin, hold inverted unroofing sequences with up-section variation in lag time that record changes in sediment source or exhumation rates as different lithospheric levels are exhumed, eroded and deposited during progressive continental break-up. These sediments deposited in syn-rift basins typically archive a more complete history of margin evolution than bedrock alone that is prone to thermal overprinting or erosion. Furthermore, zircon and rutile U-Pb-He and detrital U-Pb-He double dating studies have shown the power of coupling these data with other geochemical characteristics to further refine provenance signatures and reconstruct the complete tectonic evolution of hyper-extended continental margins. The Mauléon Basin of the Western Pyrenees is an ideal field site due to extreme crustal thinning during Cretaceous rifting followed by Pyrenean reactivation. Reactivation and deformation were minimized in the west, so many pre- and syn-rift structures are preserved and can be compared to post-rift units and structures. This study is the first major chronologic study of bedrock and detrital units completed in the Mauléon Basin and will contribute new insights into continental rifting, the evolution and structure of the Mauléon Basin and the Western Pyrenees and also plate reconstructions and kinematics of the Iberian and European plates.