PROVENANCE AND SEDIMENT DISPERSAL PATTERNS OF THE MIDDLE BLOYD SANDSTONE (EARLY PENNSYLVANIAN), NORTHERN ARKANSAS ARKOMA SHELF

The middle Bloyd sandstone is a Pennsylvanian age sandstone that occurs within the Morrowan succession of northern Arkansas. The unit is a fluvial sandstone within the predominately marine Bloyd Formation. It is stratigraphically situated between two marine units: the Brentwood Limestone member below and the marine Dye Shale member above it. The middle Bloyd sandstone is a major bluff-forming unit. It forms an outcrop belt that extends approximately 100km from east-to-west. The thickness of the unit ranges up to 35 meters, and it thins to the west where it is replaced by the non-marine Woolsey Shale. The presence of polycrystalline quartz and metamorphic rock fragments makes its composition unique from adjacent sandstone units, suggesting a difference in source. Previous studies suggest that the middle Bloyd sandstone is emplaced by a braided system on a near-strand coastal plain, but the sediment sources remain controversial. In an effort to determine the source of the sandstone, samples from the unit were taken from eight outcrop locations around northern Arkansas. LA-ICP-MS, U-Pb detrital zircon geochronology in conjunction with detailed field work and sandstone petrography aid in determining the sandstone provenance and dispersal pattern. Preliminary results suggest that the middle Bloyd sandstone contains a mixture from a cratonic source to the north and recycled sediment sources from the northeast, likely with local source contribution.