Dolomite cement microstratigraphy: A record of brine evolution and ore precipitation mechanisms, upper Knox Group, Tennessee and Kentucky, USA

Abstract Trace element changes in fluids associated with ore-forming events sedimentary basins may be recorded by contemporaneous cements, especially zoned carbonate minerals (microstratigraphy). Cement analysis using advanced mapping and analytical techniques including scanning electron microscopy cathodoluminescence (SEM-CL), charge contrast imaging, high-resolution X-ray computed tomography (XCT), laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) documents geochemical Mississippi Valley–type mineralization solution-collapse breccias of the Cambrian–Ordovician Knox Group (Tennessee Kentucky, USA). Dolomite cement zonation coincident Fe Mn can observed optical microscope CL bands as narrow 5 µm, whereas panchromatic SEM-CL reveals microfractures subzones La Ce concentrations 0.1 µm. XCT scans image a high-density (Fe-rich) dolomite zone at onset late sulfide precipitation. The transition from pre-ore to ore-stage cementation is marked increased Fe, Mn, Zn, Cd, Ga, Pb, Sr decreased concentrations. Fine-scale metal depletion cycles during this record precipitation brine response availability reduced sulfur. Except for post-ore zones generally have low Thus, microstratigraphy tracks systematic modified episodes localized mineral