A. V. Heyl
J.P. Creel
E. Roedder
1968
<p><span>These </span>deposits<span>, in Pennsylvanian limestone and shale, contain barite, fluorite, low-silver galena with "J-type" lead, and quartz, and only minor amounts of other minerals. Mineralization occurs in veins, in blankets of bedded, rhythmically banded "coontail" </span>ore<span>, and in vuggy, coarsely crystalline open-space fillings in tectonic and solution channels in limestone adjacent to faults. Except for widespread silicification, the mineralization is very similar to that of the southern Illinois </span>deposits<span>. The main stages of hypogene mineralization are: 1) sphalerite, pyrite, galena and chalcopyrite; 2) five easily recognizable substages of fluorite with intermittent quartz and barite; and 3) late calcite.More than 500 primary and 2,500 pseudosecondary </span>inclusions<span>, mainly from fluorite, were studied on the freezing and heating microscope stages. Some primary </span>inclusions<span> contain organic matter. Gross supercooling indicates slow </span>ore<span>-</span>fluid<span> movement. Recognizable planes of pseudo-secondaries (each containing 20-200 </span>inclusions<span>) yield data essentially identical with coeval primaries, but the few planes of presumed secondaries do not.The first three substages of fluorite formed from fluids that were essentially constant in temperature </span>at<span> 186°-205° C (assumed pressure correction +10° C), but increased in salinity from aproximately 10 up to 15 weight percent salts. Succeeding substages formed </span>at<span> gradually decreasing temperatures (to about 140° C) and increasing salinity (maximum 17%), with breaks marking several individual substages. A few </span>inclusions<span> in an early barite have anomalously low homogenization temperatures. Coarse selenite has primary </span>inclusions<span> full of fresh water and hence is presumed to be supergene.These data do not prove any given theory or origin for the fluids or the </span>deposits<span>, but they do place some limits on possible mechanisms of origin.</span></p>
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10.2113/gsecongeo.63.4.336
en
Society of Economic Geologists
Environment of ore deposition at the Mex-Tex deposits, Hansonburg District, New Mexico, from studies of fluid inclusions
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