Analysis of an exposure of the Viola Group in the Arbuckle Mountains, southern Oklahoma.

摘要

The Ordovician Viola Formation outcrops extensively in the Arbuckle Mts of Oklahoma. The Viola is well exposed on I-35, particularly on the southern limb of the Arbuckle anticline. Based on their petrographic characteristics, ten intervals have been recognized in this exposure. In ascending order lithologies consist of poorly washed biosparites with variable peloids and intraclasts, a phosphatic-pyritic hardground, organic carbon rich shale, fossiliferous micrites and dismicrites, packed sparites, sandy sparites, and grainstones. Ternary petrographic plots of the Viola have been used to delineate compositional fields for the different intervals. Previous work has suggested that a shallowing upward trend controlled facies development during the entirety of the deposition of the Viola. This work demonstrates that, while an overall shallowing upward motif is present, detailed facies analysis indicates that several minor fluctuations in water depth took place during deposition of the Formation.