LAUSR

Abstract The Ventana Ranges and the neighboring Claromeco basin display multiple extensional and compressional tectonic events throughout their Phanerozoic evolution. A passive continental margin setting during the early Paleozoic changed to a compressional system in the late Paleozoic, for which the Ventana Ranges are its fossilized fold and thrust belt and the Claromeco Basin, to the north-northeast, its associated foreland basin. The thermochronology study presented here and the cooling ages obtained for the Ventana Ranges are interpreted as a long-lived, probably multi-stage, exhumation event that occurred throughout the Mesozoic. The ZFT and AFT ages indicate that the Silurian, Devonian, Carboniferous and Permian units cooled during the Late Triassic to Early Jurassic (from 204.4 ± 18.8 to 146.5 ± 11.6 Ma). These ages, consistent with rifting events described for the neighboring Colorado basin (to the south-southeast), are interpreted as exhumation in the rift's northern flank. In the Claromeco Basin, a cooling event is indicated from the AFT PAZ data for the late Early Cretaceous (Barremian-Aptian, 125.8 ± 10.6 Ma), interpreted as a part of passive margin exhumation during the drift stage after the South Atlantic opening in the Valanginian-Hauterivian. The obtained ages indicate exhumation in the basin flank and are consistent with the different rifting events previously interpreted for Colorado basin.