| dc.description.abstract | Twenty-nine Woodford Shale rock samples were acquired from the Wyche-1 core derived from the Wyche Farm Shale Pit, Pontotoc County, Arkoma Basin, Oklahoma. The TOC (total organic carbon) values ranged from 3.47-16.90 wt.%, with organic matter predominantly comprised of immature Type II kerogen with significant hydrocarbon potential. A sequence stratigraphic framework of the Wyche-1 core was integrated with biomarker data to reveal additional controls on compound distribution. Water column structure and chemistry were assessed following the identification of four novel C40 aromatic carotenoids; isorenieratane, paleorenieratane, renieratane and renierapurpurane, of which, only isorenieratane had been previously documented in the Woodford Shale. Paleorenieratane was measured via CSIA (compound specific isotope analysis) and was significantly enriched relative to algal biomass, (δ13C=-12o/oo ± 1.5o/oo), suggesting carbon fixation via the reverse TCA (tricarboxylic acid) cycle utilized by the sulfur oxidizing bacteria Chlorobiaceae. The lower Woodford was characterized by isolated periods of photic zone euxinia, with the middle Woodford deposited during persistent photic zone euxinia as evinced by elevated concentrations of the C40 aromatic carotenoids. The upper member reflects ‘normal’ marine conditions characterized by bottom water anoxia. Periods of euxinia correlate with 3rd order HSTs (highstand systems tract) in the lower and middle Woodford, which likely caused cessation of upwelling and decreased circulation and vertical mixing leading to a stagnant, poorly ventilated water column permitting the development of a thick, well- defined chemocline in a restricted shelf environment. | en_US |
