Two Distinct Ore Fluids in the Viburnum Trend: Genetic Implications
John G. Viets, David L. Leach, Elwin L. Mosier, 1989. "Two Distinct Ore Fluids in the Viburnum Trend: Genetic Implications", Mississippi Valley-Type Mineralization of the Viburnum Trend, Missouri, Richard D. Hagni, Raymond M. Coveney, Jr.
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The stable carbonate platform of the U.S. midcontinent is host to the largest concentration of Mississippi Valley-type (MVT) zinc-lead mining districts in the world. Of these districts, the Southeast Missouri Lead District which includes the main Viburnum Trend and Old Lead Belt subdistricts, is unique in several ways. Lead dominates over zinc and the ores have significant amounts of copper, silver, cobalt, and nickel. Hosted in the Upper cambrian Bonneterre Formation, above the basal Cambrian Lamotte Sandstone which is underlain by felsic Precambrian basement, the Viburnum Trend is situated very low in the carbonate section when compared to the other districts of the region. Of the Ozark districts, the Southeast Missouri Lead District is also unique in its proximity to the Reelfoot Rift which is concealed beneath the Mississippi Embayment. The possible importance of the Reelfoot Rift as a pathway for brine migration from a southerly source has recently been demonstrated by Farrand Land (1985) and Farr (1987). Detailed descriptions of the mines of the Viburnum Trend are given in a special issue of ECONOMIC GEOLOGY (V. 72, NO. 3, 1977). Other informative background papers on the ore deposits of the Southeast Missouri Lead District include those by snyder and Gerdemann (1968), Gerdemann and Meyers (1972), Davis (1977) and Sverjensky (1981).
Figures & Tables
Mississippi Valley-Type Mineralization of the Viburnum Trend, Missouri
Since the first recorded discovery of lead in Southeast Missouri near Fredericktown about 1720, knowledge of the deposits has advanced in spurts as a result of outlying discoveries:
The original discoveries at Bonne Terre consisted of residual galena in clay, similar to that in the previous finds at Fredericktown. Occurrences in solid dolomite were not noted until mining of the clay pits exposed the walls of the weathered depressions. The St. Joseph Lead Co. had been established to conduct the operations and it was J. Wyman Jones. first President of St. Joe, who at that time brought about the first of the technological advances that were to occur in the district. He proposed use of the newly-invented diamond drill to explore the bed-rock showings, after observing the machines in the Vermont Marble Belt.
The first holes were drilled immediately behind the pit walls and were sufficiently successful that a shaft was sunk in 1859. Thus began the underground history of lead mining in southeast Missouri. The Bonne Terre area was the only producer from underground, hard-rock mining for the next 30 years; minor production came from shallow, surface “diggings” and veins near what is now Flat River but was insignificant and spotty. This shallow mineralization was not contiguous with the deep deposits found later.
Major discoveries of deep ore near Flat River were delayed by a negative theory of ore genesis. Although there were some advocates at that time of ore deposition from rising solutions, the most widely held theory called on downward-descending ground water. This resulted in a negative appraisal of areas where the Bonneterre Formation (the ore host) was overlain by the impervious Davis shale. It was felt that descending ground water would not be able to penetrate the 150 feet of shale. This ruled out most of the area to the south and southwest of Bonne Terre. Thus it was not until an unknown, venturesome individual drilled holes there anyway that what proved to be the largest orebodies in the “Old Lead Belt” were discovered. Great finds were made in an area nearly twelve miles long in a northwest-southeast direction. They totalled nearly 400,000,000 tons. The sub-districts of Deslodge, Leadwood, Rivermines, and Flat River eventually were interconnected underground.
The Southeast Missouri District has been the largest lead producer in the United States since 1890. Nearly a dozen companies had operations there at one time or another but, by 1933, the St. Joseph Lead Company had consolidated all the properties except those 30 miles to the southeast near Fredericktown.