Detrital zircon microtextures and U‐PB geochronology of Upper Jurassic to Paleocene strata in the distal North American Cordillera foreland basin

Abstract

Detrital zircon surface microtextures, geochronologic U‐Pb data, and tectonic subsidence analysis from Upper Jurassic to Paleocene strata in the Black Hills of South Dakota reveal provenance variations in the distal portion of the Cordillera foreland basin in response to tectonic events along the outboard margin of western North America. During Late Jurassic to Early Cretaceous time, nonmarine strata record initially low rates of tectonic subsidence that facilitated widespread recycling of older foreland basin strata in eolian and fluvial systems that dispersed sediment to the northeast, with minimal sediment derived from the thrust belt. By middle Cretaceous time, marine inundation reflects increased subsidence rates coincident with a change to eastern sediment sources. Lowstand Albian fluvial systems in the Black Hills may have been linked to fluvial systems upstream in the midcontinent and downstream in the Bighorn Basin in Wyoming. During latest Cretaceous time, tectonic uplift in the study area reflects dynamic processes related to Laramide low‐angle subduction that, relative to other basins to the west, was more influential due to the greater distance from the thrust load. Provenance data from Maastrichtian and lower Paleocene strata indicate a change back to western sources that included the Idaho‐Montana batholith and exhumed Belt Supergroup. This study provides a significant contribution to the growing database that is refining the tectonics and continental‐scale sediment dispersal patterns in North America during Late Jurassic‐early Paleocene time. In addition, it demonstrates the merit of using detrital zircon grain shape and surface microtextures to aid in provenance interpretations.

Identification of a new source for the Triassic Langjiexue Group: Evidence from a gabbro-diorite complex in the Gangdese magmatic belt and zircon microstructures from sandstones in the Tethyan Himalaya, southern Tibet

“…The I-X roundness scale reveals the smoothing of crystal edges and abrasion of crystal faces: a roundness of I emphasizes that the crystal is completely unrounded, whereas a roundness of X implies that the crystal is completely rounded. Crystal surface textures were classified using the standards of Finzel (2017) and Vos et al (2014). The analytical results of zircon CL and SEM images are presented in Text S2 ( Fig.…”

“…Based on the roundness classification of Finzel (2017), all of the analyzed grains from the sandstones of the Langjiexue Group in the Tethyan Himalaya are classified using a I-X roundness scale. It is clear that the Precambrian zircon grains are more rounded, above IV on the roundness scale.…”

Cenozoic Sediment Provenance in the Northern Great Plains Corresponds to Four Episodes of Tectonic and Magmatic Events in the Central North American Cordillera

“…IMB = Idaho‐Montana batholiths; SNB = Sierra Nevada Batholith. Modified after Finzel (). (b) Simplified geological map of the central‐western United States.…”

“…The black curve in (c) shows the relative heights of the three Mesozoic peaks. References: A = Finzel (); B–D = Fuentes et al () and Laskowski et al (); E–G = May et al (). See Figure for legends of different colors in the pie charts.…”

Detrital Zircon Geochronology of Upper Cretaceous to Paleocene Sandstones From South‐Central Wyoming: Evidence for Middle Campanian Laramide Deformation

“…In this study, we present results of U‐Pb detrital zircon geochronology from outcrops in south‐central Wyoming. These strata cover the transition and overlap of the Sevier and Laramide orogenies, with exceptional modern exposure due to Laramide uplift, and provide a critical link between the proximal Sevier foreland (Laskowski et al, ; May et al, , ) and the cratonward backbulge basin (Finzel, ). As all strata have good biostratigraphic age control (Lynds & Slattery, ), comparing U‐Pb age data from the sampled interval to potential sources provides insights on timing of uplift, exposure, and possible unroofing of source regions.…”