| The Woodford Shale is a dark, siliceous mudstone that was deposited in a rift basin during late Devonian to early Mississippian times. Three drill cores containing the Woodford Shale from the Anadarko Basin, Oklahoma, have been geochemically analyzed using a handheld energy-dispersive x-ray fluorescence instrument. Each core was analyzed at 3- to 4- inch intervals, providing high-resolution chemostratigraphy. Analysis of the following elemental concentrations was performed: Mg, Al, S, Si, P, K, Ti, Ca, Mn, Fe, Mo, Cr, Ni, Cu, Zn, Th, Rb, U, Sr, Zr, and V. Major element geochemistry supports that the Woodford is a siliceous mudstone, with little carbonate input. The relationship between iron and sulfur depicts a high degree of pyritization. A portion of the Woodford Shale appears to be iron-limited with respect to pyrite formation. Trace element enrichment factors and ratios (Ni/Co, V/Cr, and V/(V+Ni)) indicate anoxic or euxinic, oscillating with dysoxic to oxic, bottom water conditions during deposition of the Woodford Shale. |
