Geochemical and sulfur isotopic investigations into the origins of Mississippi Valley-type mineralization in the southern Appalachians and nearby areas

Quadrupole mass spectrometric and sulfur isotope investigations of Mississippi Valley-type (MVT) mineralization provide information regarding the sources of components, the precipitation mechanisms, and the areal extent of fluid provinces associated with these deposits. Quadrupole analyses of sphalerite from east Tennessee report excess CH{dollar}sb4{dollar} in primary inclusion fluids, which is compatible with ore formation resulting from migrating zinc-rich brines encountering H{dollar}sb2{dollar}S-rich gas caps at depositional sites. Sulfides from the east Tennessee deposits have {dollar}deltasp{lcub}34{rcub}{dollar}S values around +30%, indicating the parent sulfur was Upper Precambrian to Lower Cambrian seawater sulfate, reduced to completion under chemically closed conditions prior to sulfide mineralization. This is also compatible with the gas cap precipitation model, and requires an additional earlier fluid migration event to deliver sulfate to the gas caps, where it was reduced.; Sulfides from the Austinville-Ivanhoe district in southwest Virginia have {dollar}deltasp{lcub}34{rcub}{dollar}S values ranging from about +10 to +22%. If the same parent sulfate responsible for east Tennessee mineralization also formed the Austinville-Ivanhoe deposits, it must have been only partially reduced under chemically open conditions. Alternatively, a different parent sulfate, with a lighter isotopic composition than in east Tennessee, could have been reduced to completion. In either event, the two regions represent separate sulfur mineralization provinces.; Barite from the Cartersville district, in Georgia, has {dollar}deltasp{lcub}34{rcub}{dollar}S values that are lighter than east Tennessee sulfates. The Cartersville district must have had a parent sulfate with a lighter {dollar}deltasp{lcub}34{rcub}{dollar}S value than in east Tennessee, which requires that it was of a different age, and represents a separate sulfur province.; The central Tennessee and central Kentucky districts lie to the west of the Valley and Ridge province. Sulfides from these districts are 20 to 40% lighter than in east Tennessee, and must at least have been reduced under different conditions than in east Tennessee, and likely had a different parent sulfate. The {dollar}deltasp{lcub}34{rcub}{dollar}S values are similar to those of mid-continent MVT districts farther to the west, suggesting that the central Tennessee and central Kentucky districts may be genetically related to those deposits.