The organic matter composition of the Devonian/Carboniferous deposits (South Flank of Arbuckle Anticline, Oklahoma, USA)

The palynological investigation was carried out on the Woodford Shale and Sycamore Limestone samples from Interstate 35 roadcut section (I-35) on the south flank of the Arbuckle Anticline (Oklahoma, USA). All samples were collected from the 54 m long section. According to palynostratigraphy, the section was tentatively divided into three stages: Frasnian, Famennian and Tournaisian but due to poor miospores representation it was not possible to establish any single miospore zone. All samples were strongly dominated by the amorphous organic matter and by marine palynomorphs, mostly prasinophytes. The analysis of the relative frequency, fluctuations in acritarchs diversity, and morphotype variability generally suggest deposition in an open-marine, deep-water basin. Based on palynofacies analysis, the section was divided into three palynofacies: lowest (fully marine, I), middle (fully marine but closer to the shoreline, II), and the topmost palynofacies (III) which was also marine, but with a weak regressive signal.