Geochemical and Petrographic Evidence for Fluid Sources and Pathways during Dolomitization and Lead-Zinc Mineralization in Southeast Missouri: A Review
Regional geological studies in southeastern Missouri have made a significant contribution to knowledge of the origin of Mississippi Valley-type mineralization and the late diagenetic history of sedimentary rocks throughout this part of the Midcontinent. In addition to mineral exploration, investigations such as these provide insights into basinal processes such as migration and distribution of petroleum, dolomitization, and porosity modification of carbonate petroleum reservoir rocks. Cathodoluminescent microstratigraphies of epigenetic dolomite cements indicate that mineralizing basinal fluids altered carbonate rocks over a much larger area than was affected by sulfide mineralization. Trace element distributions in southeast Missouri also indicate that sedimentary rocks, over a large region, were altered by basinal fluids from both a southern (Arkoma Basin) and a northern or northeastern (possibly the Illinois Basin) source. Fluid inclusions in sphalerites and dolomites throughout southern Missouri and northern Arkansas indicate that mineralizing basinal brines were very saline (≈16 wt % equiv. NaCl] and warm (≈80° to 150°C). The lack of discernible thermal gradients in fluid inclusion temperatures from regionally extensive epigenetic dolomites and the range of fluid inclusion salinities indicate that more than one basinal fluid was involved in dolomitization and associated Pb-Zn ore deposition. Carbon and oxygen isotope compositions of dolomites show that basinal fluids evolved in chemical compositions with time and indicate interactions of fluids from at least two sources. Studies of strontium compositions of dolomite cements south and east of the Viburnum Trend subdistrict provide further evidence of an Arkoma-Ouachita source of one of these fluids. Lead isotope compositions of galenas, however, indicate multiple sources: 1) the Illinois Basin, 2) the Arkoma Basin, 3) and the underlying local granitic basement. Distinct northern and southern basinal sources are postulated for sulfur based on sulfur isotope data from galenas. Taken as a whole, available geochemical and petrographic evidence indicate that dolomitization and Pb-Zn mineralization in southeast Missouri were the result of a more complex, multiple-basin fluid interaction than previously recognized.
J. M. Gregg and K. L. Shelton, "Geochemical and Petrographic Evidence for Fluid Sources and Pathways during Dolomitization and Lead-Zinc Mineralization in Southeast Missouri: A Review," Carbonates and Evaporites, vol. 4, no. 2, pp. 153-175, Springer Verlag, Sep 1989.
The definitive version is available at http://dx.doi.org/10.1007/BF03175105
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Basin Fluid Interaction; Lead/Zinc; Mineralization; Mineralizing Fluid; Mississippi Valley Type Deposit; Multiple Source; USA, Missouri
International Standard Serial Number (ISSN)
Article - Journal
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