Comparing Detrital Geo- and Thermochronology of Brooks Range Modern River Sediment with Stratigraphic Elements of the Colville Foreland Basin, Arctic Alaska: Insights for Basin Evolution and Tectonics

The Jurassic–Cretaceous collisional history of the ancestral Arctic Alaska Brooks Range has sparse absolute constraints on allochthon-belt kinematics because the few thermochronologic studies have primarily used apatite fission-track (FT) cooling ages to understand recent Cenozoic uplift of the modern orogen. Here, we use a multimineral detrital approach to broadly survey the early thermal and structural history of the Brookian orogen and compare results with the well-known stratigraphic record of the Colville Foreland Basin to explore conceptual models of foreland basin filling. Sands from 33 modern rivers across >600 km along the orogen were analyzed using detrital-zircon (DZ) and detrital-apatite (DA) U–Pb and FT double-dating. DAU–Pb data reveal early-Cretaceous thermal overprinting of parautochthonous rocks of the northeast Brooks Range during peak orogenesis. While older DZFT age components correspond to pre- and syn-collisional events accompanied by subsidence and deposition of a thick foredeep-wedge, a hiatus from ca. 110–75 Ma coincides with deposition of the Brookian megasequence Torok-Nanushuk and Seabee-Tuluvak clinothems. Basin strata DZU–Pb indicates Brook Range sediment dispersal was limited relative to voluminous sediment delivery from Russian Chukotka. The paucity of late-Cretaceous FT ages suggests a post-tectonic period of slow hinterland exhumation, with western sediment-supply and eustasy as primary drivers of rapid progradation/transgression of early Brookian clinothems. Post-75 Ma DZ/DAFT ages reflect orogenic rejuvenation and basement-involved thrusting that resulted in exhumation of the foredeep and syn-tectonic wedgetop basin development in the northeast Brooks Range. This study highlights that modern sediment surveys of orogens are informative of stratigraphic sequences in associated sedimentary basins.