MAPPING THE BARTON 7.5–MINUTE QUADRANGLE IN COLBERT COUNTY, ALABAMA AND PROVENANCE ANALYSIS OF THE HARTSELLE SANDSTONE USING U–Pb GEOCHRONOLOGY

The Barton 7.5–minute quadrangle is located in the northwestern-most corner of Alabama and contains upper Mississippian strata of the Tuscumbia Limestone, Pride Mountain Formation, Hartselle Sandstone, and Bangor Limestone. The Mississippian section is unconformably overlain by Cretaceous strata of the Tuscaloosa Group and unconsolidated Quaternary alluvium. The Tuscumbia Limestone, exposed in the lowest portions of valleys and rarely exposed contains chert blocks and correlates to a period of low clastic influx during shallow basin conditions. The overlying Pride Mountain Formation, a shale-dominated unit with interbedded limestone and sandstone intervals, represents the initiation of clastic sedimentation in the Black Warrior basin, which culminates in the overlying Hartselle Sandstone, a barrier island complex composed of very-fine to medium grained, white to tan, cross bedded sandstone. The overlying Bangor Limestone, a dark-gray to black, commonly micritic limestone represents restricted basin conditions, with a decrease (but not absence of) clastic sediment, and an increase in the accumulation of organic material.

The provenance of sediment within the Hartselle Sandstone may offer insight into the basin dynamics active during early orogenesis. We will present U-Pb zircon, apatite, and rutile data to assess models for the routing of clastic sediment into the Black Warrior basin, including a (1) continental drainage system (similar to the modern Mississippi River), and (2) locally sourced, orogenic system (similar to the Brahmaputra River drainage in and from the Himalaya Mountains).

Keywords: Hartselle Sandstone, provenance, geochronology, Black Warrior Basin