INITIAL INVESTIGATION OF DETRITAL MUSCOVITE AGES FOR THE ARKOMA-OUACHITA BASIN, WITH COMPARISON TO RESULTS FROM THE GREATER BLACK WARRIOR BASIN

The Arkoma-Ouachita Basin (AOB) and the Greater Black Warrior Basin (GBWB) received sediment during the Late Mississippian and Early Pennsylvanian due to orogenic uplift and rapid deepening of foreland basins. The AOB was relatively sediment starved until the onset of continental glaciation initiated sea level regression and the construction of continent-scale river systems. A large-scale regional unconformity marks the Mississippian-Pennsylvanian boundary in both the AOB and the GBWB. Laser ⁴⁰Ar/³⁹Ar ages (n>100) were determined in the Auburn Noble Isotope Mass Analysis Lab for detrital muscovite from two Carboniferous sandstones from the AOB. The muscovite grains are interpreted to represent first-order, non-recycled sediment, and their ages permit interpretation of the sediment provenance and investigation of possible connections in sedimentation between the Ouachita and Black Warrior Basins. Sample OK12-54 from the uppermost Mississippian Stanley Group of the AOB has a prominent Taconian age mode (ca. 445 Ma), and ca. 42% of the analyzed grains are older than 445 Ma, with subordinate modes at ca. 490 Ma and 520 Ma. Also, two muscovite crystals with ages of ca. 625 Ma were obtained for this sample, suggesting a possible Gondwanan source with Pan-African age. In contrast, Sample OK12-39 from the Pennsylvanian Jackfork Formation of the AOB is dominated by a 365-375 Ma mode that is skewed to ages that are generally not older than 455 Ma. An uppermost Mississippian Parkwood sample from the GBWB has three distinct modes at 440, 365, and 320 Ma, taken to represent the Taconic, (neo)Acadian, and Alleghanian events, while many Pennsylvanian Pottsville samples show a dominant Taconic mode and a lesser Neoacadian mode (Moore, 2012; Uddin et al., 2016). In the GBWB Pennsylvanian samples, an Alleghenian mode is generally present and increases in proportion upsection. Such an Alleghanian mode is completely absent from our two initial samples of the AOB. The initial results from the AOB show significant similarities (e.g., presence of Neoacadian ages) but also important differences (the abundance of pre-Late Ordovician ages in the Mississippian AOB samples), that will be examined more fully in future provenance studies.

Moore (2012), AU Thesis, 132 p.; Uddin et al. (2016), J. Sed. Res. v. 86, 1287-1297.