Age and deposition of the Fort Crittenden Formation: A window into Late Cretaceous Laramide and Cenozoic tectonics in southeastern Arizona

Abstract The Upper Cretaceous Fort Crittenden Formation exposed in the Santa Rita and Huachuca Mountains of southeastern Arizona is a syntectonic deposit that has been associated with Laramide tectonic activity. However, spatio-temporal relationships among sedimentation, magmatism, basement exhumation, possible flat slab-related processes southern region remain poorly understood. Age controls for uplift erosion local topography deposition response to deformation particularly poor. comprises 800–2500 m locally derived fluvial alluvial fan sedimentary rocks records paleodrainage reorganization active tectonics. Changes facies, provenance, paleoflow suggest tectonically partitioned intraforeland basin. New detrital zircon data constrain timing between ca. 86 Ma 76 Ma. lack depositional age zircons throughout majority consistent magmatic lull Cordilleran arc 90 overlying Salero Late intrusions are expressions renewed magmatism at 75 Lu-Hf indicate magmas evolved from contamination old juvenile crust. When interpreted conjunction other regional sets, our study indicates front migrated eastward into southwestern Mexico by Thermal modeling apatite fission track (U-Th)/He granitic clasts Cretaceous–Paleocene (ca. 76–55 Ma) heating related cooling exhumation during Eocene Oligocene.