SEDIMENT DISPERSAL PATTERNS OF MISSISSIPPIAN TO PENNSYLVANIAN CLASTIC ROCKS WITHIN THE ARKOMA SHELF, NW ARKANSAS

Multiple late Mississippian and early Pennsylvanian age clastic rocks are cropped along the Arkoma Shelf, NW Arkansas. Two models, local vs. long distance transported, had been proposed to interpret the sources and dispersal patterns. In this study, a series of samples of late Mississippian to early Pennsylvanian age clastic rock units were collected from outcrops in NW Arkansas. LA-ICP-MS U-Pb detrital zircon geochronology was utilized to constrain and evaluate different depositional models. In addition, four Ordovician to Devonian age sandstones were analyzed to provide potential recycled sediment source age signatures. Results show that there are five distinct age groups, including 0.4-0.6 Ga, 1.0-1.2 Ga, 1.3-1.5 Ga, 1.6-1.8 Ga, and >2.5 Ga. Based on known regional source terranes, the oldest population (>2.5 Ga) is attributed to the Superior Province of the Canadian Shield; the 1.6-1.8 Ga population corresponds well with Yavapai-Mazatzal provinces; the 1.3-1.5 Ga population is not tightly constrained, but may originate from a localized midcontinent source, such as the Ozark Dome; the 0.4-0.6 Ga group is believed to have originated from Acadian and Taconic Orogenies; and the 1.0-1.2 Ga range is mostly likely derived from the Grenville crystalline rocks. Very similar age distributions of late Mississippian and early Pennsylvanian rocks suggest that majority of sediments were same sourced, either directly derived from cratonic source to the north and northeast or recycled from previous sediments. Local topographic variations play a critical role for sediment dispersal patterns along the Arkmoa Shelf.