Abstract

Reefs dominated by bryozoans and crinoids are present in the Kinderhookian Compton Formation and basal Osagean Pierson Formation (St. Joe Group) in southwestern Missouri and northwestern Arkansas. These relatively small, Waulsortian-like buildups formed as a result of baffling and trapping of sediments, and were deposited in moderate-depth to shallow-water environments. Some of the reefs and surrounding strata in the Compton were uplifted and displaced downslope, to the north-northwest, soon after deposition as a result of early Ouachita-related forebulge tectonism. Marine cements in the form of bladed and radiaxial-fibrous calcites of original high-Mg calcite mineralogy are present in the reef deposits. The reefs subsequently underwent some meteoric dissolution prior to pervasive meteoric calcite cementation. Later, minor dolomitization occurred in some of the Compton reefs, whereas there was telogentic dissolution, porosity formation, and oil emplacement in the Pierson reefs. These attributes serve as analogs for the recognition of subsurface reefs in the Compton and Pierson Formations in southern Kansas and northern Oklahoma, which are known to be present locally as oil reservoirs.