A. V. Heyl
J. L. Jolly
1964
<p><span>The </span>Central<span> </span>Kentucky<span> </span>mineral<span> </span>district<span> occupies the greater part of the Blue Grass lowland of </span>Kentucky<span>, which lies astride the Lexington dome and the Cincinnati arch. The oldest exposed rocks of the mineralized area are limestones of Middle Ordovician age. The </span>paragenesis<span> throughout the </span>district<span> is constant and traceable, although the relative abundance of minerals varies from vein to vein. The </span>mineral<span> association, areal distribution of the ore minerals, and comparison with other epithermal deposits indicate that the </span>Central<span> </span>Kentucky<span> veins are epithermal. The ore deposits have a </span>district<span>-wide lateral </span>zoning<span> </span>in<span> a concentric pattern. Near the middle of the </span>district<span>, and within the Lexington dome, are two centers of fluorite-calcite-dark sphalerite veins that form Zone 1. Surrounding these centers is a much larger Zone 2 </span>in<span> which nearly all the veins contain fluorite, barite, calcite, and two-colored (yellow-black) sphalerite. Galena is absent or present </span>in<span> very minute quantities </span>in<span> Zones 1 and 2. </span>In<span> Zone 3, which surrounds Zone 2, barite, galena, and bright-colored sphalerite are the principal minerals. Fluorite is absent, or present only </span>in<span> traces. Textures of the </span>mineral<span> veins change from bands of coarse comb crystals </span>in<span> Zone 1 to mostly colloform bands </span>in<span> the outer zones. Structural control of the ore is related to faults and fractures transecting the collapsed Lexington dome and is an important factor </span>in<span> the distribution of </span>mineral<span> veins. The </span>district<span> has many of the mineralogic, zonal, and structural features of the </span>Central<span> Tennessee, </span>Kentucky<span>-Illinois, and Pennine, England, </span>mineral<span> districts, which suggest that the origins of these districts were similar. The ores </span>in<span> the </span>Central<span> </span>Kentucky<span> </span>district<span> were probably deposited from ascending thermal solutions of slightly lower temperatures than those that formed the deposits </span>in<span> the </span>Kentucky<span>-Illinois </span>district<span>. The solutions are believed to have been derived from a deepseated magmatic source centered beneath the Lexington dome, but they may have been greatly diluted by ground waters within the dome. The innermost zone probably is nearest to the emanative centers.</span></p>
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10.2113/gsecongeo.59.4.596
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Society of Economic Geologists
Mineral paragenesis and zoning in the central Kentucky mineral district
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