--> Abstract: The “Chattanooga Shale” of the Ozark Uplift Region (Northeastern Oklahoma, Southwestern Missouri, and Northern Arkansas) is herein renamed as the Eagles Bluff Shale,Darwin Boardman, Article #90097 (2009)

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The “Chattanooga Shale” of the Ozark Uplift Region (Northeastern Oklahoma, Southwestern Missouri, and Northern Arkansas) is herein renamed as the Eagles Bluff Shale

Darwin Boardman1 , Jim Puckette2, Ibrahim Cemen3, Anna Cruse4

1Oklahoma State University , 2Oklahoma State University , 3Oklahoma State University , 4Oklahoma State University

The “Chattanooga Shale” of the Ozark Uplift (southwestern Missouri, northwestern Arkansas, and northeastern Oklahoma) represents a high shelf black shale facies that grades into the Woodford Shale. Based on surface and subsurface mapping, this shale is unrelated to the Chattanooga Shale sensu-stricto of the southern Appalachian Basin.. The type region of the Chattanooga Shale contains a subequal amount of Frasnian as well as Famennian Devonian strata contrasted to the Ozark “Chattanooga” which is virtually all Famennian.

We propose the name Eagles Bluff Shale to represent the Ozark Uplift “Chattanooga Shale” which has also been previously referred to as the Noel Shale of Missouri and the Eureka Shale of northwestern Arkansas. The type section for the proposed Eagles Bluff Shale is along a major roadcut on Highway 10 northeast of Tahlequah, Oklahoma in which both the lower as well as upper contacts are exposed. Additionally, just south of that section a principle reference section occurs at No Head Hollow in roadcuts along the same highway. We show a cross section from outcrops in northeastern Oklahoma, northwestern Arkansas and southwest Missouri as well as subsurface cross sections that demonstrate spectral gamma ray correlation across the Arkoma Basin.

The Eagles Bluff Shale in outcrop differs from the Woodford Shale in several significant ways in that is much thinner (10-20 meters), lacks nonskeletal phosphate, and lacks significant chert beds. A transitional facies occurs in the Lawrence Uplift of the northeastern Arbuckle Mountains in which the Woodford Shale is (80-90 meters), contains non-skeletal phosphate, but contains no radiolarian-bearing cherts.

 

 

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