A geochemical evaluation of the genetic relationship between Ouachita Mountains Paleozoic rocks and the Mississippi Valley-type mineralization in the southern Ozark Region, USA

Radiogenic Pb Enrichment of Mississippi Valley-Type Metallic Ore Deposits, Southern Ozarks: Constraints Based on Geochemical Studies of Source Rocks and Their Diagenetic History

“…Zoned dolomite cements in fractures and breccias indicate that the late diagenetic dolomites likely precipitated from hot, saline brines subjected to extensive interaction with clastic lithologies, rather than as replacement [37]. Additionally shown are the stratigraphic locations of samples analyzed for this study (triangles) and previous studies [9,10], and the hosts of the Northern Arkansas and the Tri-State ores (black and blue bars, respectively). The height of the columns is not intended to represent the thicknesses of the units.…”

“…Location of samples analyzed in this study (triangles) and those of previous studies: squares [9,10], diamonds [9,28], and circles [9,28]. Modified from [10].…”

“…Geochemical studies indicate that the Mississippi Valley-type (MVT) ores were produced from a mixing and cooling of these sedimentary, basinal brines by associated meteoric or connate waters [4]. Previous investigations of the mid-continent MVT Pb and Zn mineralization (Figure 1) have been conducted, resulting in a large amount of geological and geochemical data, as well as numerous theories as to the source of the MVT ore metals and mineralizing fluids [5][6][7][8][9][10]. In the Ozark region, the linear trend defined by the Pb isotope compositions of the MVT ores suggest their formation involved a mixing of metals from two end-member components [7][8][9][10].…”

“…Extensive geochemical studies of rocks from the southern Ozark region and the Ouachita Mountains (Figure 1) have been carried out in order to constrain the two end-member components in the ores from the Northern Arkansas and the Tri-State boniferous shales and sandstones of the Ouachita Mountains [10], the various cherts from the Devonian-Lower Mississippian Arkansas Novaculite [11,12], and from the Lower Mississippian Boone Formation (the lower Boone penecontemporaneous chert and the upper Boone tripolitic and diagenetic chert) [13,14]. While the less radiogenic component has been generally attributed to various shale and sandstone units [9,10], the more radiogenic component has not yet been identified. Whole-rock Pb isotope analyses conducted for this study may help better constrain the more radiogenic component that contributed Pb to the ores.…”

“…Fluid flow through confined aquifers in the Ouachita Mountains and the Ozark Plateaus is very likely. Available Pb isotopic data for samples of sphalerite ore from the Northern Arkansas and Tri-State Mining districts [9,28] and for various rock units [9][10][11][12][13][14] have been incorporated into this study for a comprehensive understanding of the MVT ores.…”