Geological Society of America

19 Carbon in the Geosphere

Tuesday, 13 March 2018
1:30 PM - 4:25 PM
Conway Room

LATE DEVONIAN ORGANIC-RICH WOODFORD SHALE DEPOSITS AND THE FRASNIAN/FAMENNIAN (F/F) AND DEVONIAN-CARBONIFEROUS (D/C) GLOBAL ANOXIC EVENTS

Paper number: 19-3
Program: Theme Sessions
Time: 2:10 PM – 2:30 PM

Authors

Carlos E. Molinares Blanco Presenting Author
The University of Oklahoma, Norman, OK
Bryan Turner
Morrison Natural History Museum, Morrison, CO
Roger M. Slatt
The University of Oklahoma, Norman, OK
Nevin Kozik
Florida State University Earth, Ocean and Atmospheric Science, Tallahassee, FL
Seth Young
Florida State University Earth, Ocean, & Atmospheric Science, Tallahassee, FL
Richard P. Philp
The University of Oklahoma, Norman, OK
Douglas Elmore
University of Oklahoma, Norman, OK
Andrea Miceli-Romero
Texas A&M University, College Station, TX
Miguel F. Etayo-Cadavid
BP Lower 48, Houston, TX

Abstract

The Woodford Shale was accumulated in the Late Devonian – Early Mississippian time when anoxic global events have been described for the Frasnian/Famennian (F/F) boundary (Lower and Upper Kellwasser events), and the Devonian / Carboniferous boundary (Hangenberg event). This work shows a compilation of d¹³C stable isotopes, organic geochemistry, biomarkers, palynology, thin sections, SEM-EDX and X-ray fluorescence element compositional analysis from Woodford Shale rocks cored by the Wyche-1 well, Lawrence Uplift, Pontotoc Co., Oklahoma. The core was subdivided into Welden Shale and Lower, Middle and Upper Woodford intervals, where nine (9) lithofacies were defined. A series of positive isotopic Carbon excursion were correlated with the Kellwasser and Hangenberg events, thanks to the temporal restrictions supported by a detailed conodont zonation reported from adjacent localities.

The stratigraphic relationship between the organic rich Woodford Shale deposits with the positive d¹³C isotopic excursions, the anoxic (euxinic) shallow seawater conditions interpreted by biomarker (C40 Carotenoids and Aryl-Isoprenoids) compounds help to support the idea that the organic-rich middle Woodford Shale deposits was related with the F/F anoxic and faunal crises. Moreover, molybdenum/TOC ratios show changes in the paleo-redox and deep-water circulation conditions from more restricted circulations in the Lower/Middle Woodford Shale toward more open marine deep-water circulation during the accumulation of the Upper Woodford Shale. The titanium (Ti) concentrations relative to aluminum (Al) reflect a possible coastline progradation in agreement with a higher content of pollen and spores respect to the marine palynomorphs (i.e. tasmanites and acritarchs).

Geological Society of America Abstracts with Programs. Vol. 50, No. 1

doi: 10.1130/abs/2018SC-310250

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