Abstract

The Viburnum mineralized area lies near the southern edge of the central stable region of the North American craton. Erosion of the Precambrian preceded establishment of basins and uplifts in early Paleozoic time. Shelf deposition prevailed in the Late Cambrian and Early Ordovician, followed by emergence and erosion resulting in the post-Knox unconformity. Silurian and Devonian deposition were followed by severe erosion, and Lower Mississippian strata were laid down on a rough karst surface. Emergence since Pennsylvanian time has exposed the Ozarks and surrounding areas to continous erosion, and the region has been stable. Block faulting surrounds the core of the uplifted St. Francois Mountains; farther west, long faults and joints trend northwest and northeast.The Upper Cambrian series in southeast Missouri comprises six formations, which are, in ascending order: Lamotte Sandstone, Bonneterre Formation, Davis Formation and Derby-Doerun Dolomite (Elvins Group), Potosi Dolomite, and Eminence Dolomite. These rocks are dominantly carbonates with varying amounts of detrital material, except for the basal Paleozoic sandstone, the Lamotte. In Late Cambrian time, clastic sedimentation was dominant in the Upper Mississippi Valley, with a progressive increase in carbonates southward to the Ozarks. Although hindered by considerable distance and a paucity of subsurface data, correlations between the two regions are presented with reasonable confidence.

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