Hydrogeology

The Hydrogeologic Setting
The Arbuckle-Simpson aquifer is contained within several rock formations. Rocks of the Arbuckle Group consist of limestones and dolomites that were deposited between 520 and 480 million years ago in Late Cambrian and Early Ordovician time. The carbonate sediments were deposited on a vast, shallow-water platform that extended from northeast New Mexico into northeast Canada. Rocks of the Simpson Group consist of sandstone, shale, and limestone that were deposited 480 to 460 million years ago in Middle Ordovician time.

Rocks of the Arbuckle and Simpson Groups are exposed at the land surface in three prominent uplifts separated from each other by large, high-angle faults. The southwestern outcrop is on the Arbuckle Anticline, a geological structure that was formed 300 million years ago when intensive folding and faulting of a thick sequence of Paleozoic rocks formed the ancestral Arbuckle Mountains. Originally rising several thousand feet above the surrounding plains, the mountains have been eroded to their present-day maximum relief of 600 feet. Topography over the steeply dipping strata is very rugged. Road cuts along Interstate 35 provide unique views of the thick sequence of Paleozoic rocks and complex structure of the Arbuckle Anticline.

The eastern outcrop is on several structural features, of which the Hunton Anticline is the most prominent. The central outcrop is on the Tishomingo Anticline. The Structural deformation on these two anticlines is much less pronounced than on the Arbuckle Anticline, and the topography consists of gently rolling plains.

Source: Oklahoma Water Resources Board, 2003, The Arbuckle-Simpson Hydrology Study Management and Protection of an Oklahoma Water Resource: Oklahoma Water Resources Board Fact Sheet, 4 p.