PATTERNS AND DRIVERS OF CONTINENTAL-SCALE SEDIMENT TRANSPORT IN LAURENTIA DURING THE LATE MISSISSIPPIAN FROM DETRITAL ZIRCON PROVENANCE

The Late Mississippian is considered an important time interval in the evolution of Laurentia, marking the transition from dominantly carbonate deposition on a stable shelf during the Early-Middle Mississippian, to more widespread clastic deposition associated with orogenesis in the Pennsylvanian to Permian. In the US midcontinent, Upper Mississippian (Chesterian) sandstones preserve the earliest record of this evolving setting. In Kansas, the sandstones fill N-S oriented incised valleys that developed across a broad carbonate platform that covered much of the cratonic interior. This study investigates the provenance of these incised valley fill (IVF) systems using detrital zircon U-Pb geochronology. Here we report 1037 new concordant detrital zircon U-Pb ages from nine samples of Upper Mississippian sandstone. Seven of the samples were obtained from core from three boreholes, the Mary Jones #2, MLP Black, and Hitch Unit 8-3, located in the axis of an IVF complex in southwestern Kansas. We also analyzed two samples collected from outcrops of the Chesterian Batesville and Wedington sandstones in northwestern Arkansas. The U-Pb age spectra are characterized by prominent clusters of Grenville (900-1300 Ma) and Taconic-Acadian (350-500 Ma) ages and subordinate and variable older age groups, consistent with major derivation from Appalachian region. The results, when compared to published detrital zircon ages for early to middle Paleozoic sandstones, suggest age distributions for Chesterian sandstones are distinct and unlikely to have been recycled from older units. Comparisons with U-Pb data from age-equivalent units from the Appalachian foreland basin, Illinois basin, Arkoma Shelf, Ozark Dome, Black Warrior basin, and Grand Canyon indicates relatively uniform provenance across North America. The recognition of similar provenance for Upper Mississippian strata across Laurentia supports the establishment of a major transcontinental sediment delivery system in the Late Mississippian. Establishment of this system was likely the result of orogenesis on the eastern Laurentian margin; whereas, local variations in the age signatures appear to be controlled by N-S drainage networks, influenced by glacioeustatic fluctuations.