Bacteriogenic Origin of Secondary Minerals in Ohio Based on Carbon and Sulfur Isotope Compositions
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Date
1998-06
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The Ohio State University
Abstract
The origin of secondary minerals in northwestern Ohio has been attributed to a
variety of causes including magmatic and bacterial activity. This research was conducted
to determine whether secondary calcite, pyrite, sphalerite, galena, and celestite in Ohio
result from bacterial processes. This combination of minerals is similar to those of
Mississippi Valley type deposits, which have yielded economic wealth in other areas. The carbon isotope composition in secondary calcite establishes a link with
petroleum by exhibiting S13C values of -21.5o/oo to -27.6o/oo. The δ34S values of sulfide
minerals (-24.2o/oo to +7.0o/oo) demonstrate consistent depletion in the heavy sulfur
isotope compared to coexisting sulfate minerals whose δ34S values range from +28.4%o/oo
to +66.4o/oo. The isotope fractionation of carbon and sulfur minerals confirms that sulfurreducing
bacteria metabolized hydrocarbons by means of oxygen derived by reduction of
sulfate to sulfide. The CO2 and H2S released by bacteria resulted in the deposition of
secondary carbonate and sulfide minerals in the rocks of northwestern Ohio.