DETAILED SEDIMENTOLOGY AND INORGANIC GEOCHEMISTRY OF THE DOLGEVILLE FORMATION AND UTICA GROUP OF THE CENTRAL MOHAWK VALLEY, NY

While the stratigraphy and sedimentology of the shelf carbonates of the Ordovician Trenton Group exposed in the Mohawk Valley of Central New York is well documented, a similar level of detail for the overlying mudstones of the Utica Group is lacking. This is likely due to the difficulties of observing fine sedimentary structures and layering in outcrop exposures of mudrock compared to limestone. Drill cores collected by NL Industries along the outcrop belt of the Trenton and Utica groups represent an unprecedented opportunity to study the detailed sedimentology, stratigraphy, and geochemistry of the Utica Group. This study combines detailed sedimentologic description, microscopic imaging of hand samples with a Dino-Lite digital microscope, thin section petrography, and elemental abundance measurements using a Bruker Tracer III pXRF to investigate the spatial and temporal variability of Utica Group mudrocks within the Mohawk Valley.

Lithologic descriptions have revealed a variety of distinct facies including black siliceous, argillaceous, and carbonaceous mudstone, sharp based normally graded gray calcareous silty mudstone, cross-stratified and burrowed calcareous silty mudstone, and matrix and grain supported sandy mudstone. These facies record distinct depositional processes within a deepening foreland including turbidity currents, debris flows, and remobilization of seafloor muds by wind, storm, and contour currents.

XRF spectroscopy can provide proxies for siliciclastic, carbonate, and clay mineral input which can be used to highlight contributions from source terranes including the craton and carbonate shelf to the west, Taconic orogenic wedge to the east, and the Adirondack Massif to the north. Other elemental proxies can highlight changes in redox conditions and organic matter accumulation. Coupled with lithologic descriptions, elemental data represents a powerful tool to better understand the Taconic Orogeny and resultant foreland basin.