Masters Theses

Date of Award

12-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

Otto C. Kopp

Committee Members

Kenneth R. Walker, Kula C. Misra

Abstract

The Right Fork area is located in Overton and Jackson Counties in Central Tennessee in the Central Basin of the Interior Lowlands Physiographic Province. One hundred and fifty-five samples were selected from fifteen core holes for petrographic and chemical analysis. The major areas of interest were: (1) to determine the mineralogical and chemical relationships between host breccias and gangue, (2) the relation-ship between sphalerite and the kind(s) of gangue present, (3) the distribution of trace elements in gangue minerals, and (4) to determine whether any obvious characteristics, such as the nature of cathodo-luminescent zones, could be used as a guide to mineralization.

A study of the gangue minerals reveals that there are at least two types of dolomite and three generations of calcite present. The cathodoluminescent patterns observed occur throughout the study area and appear to be identical to the patterns observed in the Elmwood zinc mine, which is located approximately 40 kilometers southwest of the Right Fork area.

Three major gangue types, Dolomite I, Dolomite II and Calcite I are composed of five zones which can be correlated among the three gangue types. The first obvious sphalerite deposition appears to have begun during the deposition of zone 3 in dolomite and calcite.

Chemical analyses suggest that there is no consistent relationship between the mineralogy of the host breccia fragments and the carbonate minerals found in adjacent fractures. However, correlation studies of breccia fragment-gangue sample pairs suggest that the chemistry of the gangue minerals may be dependent on the chemistry of adjacent breccia fragments.

There was no observable preference for mineralization with respect to gangue minerals. Both dolomite and calcite are associated with mineralization when mineralization is observed. Further, there was no dominant gangue mineral associated with sphalerite mineralization. X-Ray fluorescence analyses show Fe concentrations in zoned calcite samples with higher average values (2121 ppm) than the unzoned calcite samples (643 ppm). The Fe, Mn, and Zn, concentrations in Dolomite I are much higher than for both zoned and unzoned calcite samples. Correlation analyses seem to suggest that the amount of dolomite present in the gangue may control the amounts of Fe and Zn that is present. Decreasing Mg values associated with calcitic gangue correlates positively with Fe and Zn. This relationship may suggest that mineralization is associated with calcitic gangue.

Photographs were taken of samples from two cores (one obviously mineralized and the other apparently nonmineralized) to determine whether changes in cathodoluminescent character occurred adjacent to sphalerite mineralization. It was hoped that gangue from areas of mineralization might show increased cathodoluminescent intensities. Unfortunately, there were no discernable changes in either the cathodoluminescent color or intensity.

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