ABSTRACT

Northeastern Arkansas lies in the upper Mississippi embayment of the Gulf Coastal Plain. The embayment is generally considered to be post-Comanchean in age, but evidence indicates it may be Cambrian or older. Paleozoic rocks related to those found in the Ozarks, Arkansas Valley and Ouachita Mountains of the Paleozoic outcrop area are found in the embayment beneath Coastal Plain sediments. Correlations of pre-Atoka rocks in Arkansas with equivalent rocks of adjacent states indicate that treatment of the embayment on a regional rather than a local basis is valid. Maximum development of the Ozark uplift in northeastern Arkansas is marked by a truncated belt of Siluro-Devonian rocks encircling the uplift. Many Paleozoic unconformities should be present in the embayment, especially near the Fall Line. A fault has been identified in Crittenden County. This may be related to a fault system near the embayment trough. The St. Peter sandstone may be the most prospective pre-Pennsylvanian formation in the embayment for oil production. Pre-Mississippian rocks wedged-out against Chattanooga or younger black shales are prospective. Atoka sands may be productive of gas. Ouachita type rocks, as extended into the embayment, are thought to have poor possibilities for production.