| Abstract: | Core samples from a roll-front uranium deposit in south Texas have been analyzed for iron sulfide content and mineralogy, organic carbon content and the abundance of carbonate, iron, manganese and titanium. Sulfide occurs almost exclusively as the iron disulfides pyrite and marcasite, in concentrations as high as 2 percent of the coarse (>62 ?m) fraction. Marcasite is particularly abundant relative to pyrite in the vicinity of the roll front. Because marcasite precipitation requires acidic pH‘s and the most likely mechanism for generating a low pH is oxidation of preore sulfide, it is argued that marcasite formation is, at least in part, related to roll-front development. Organic carbon analyses from various representative parts of the deposit are uniformly low (<0.1 percent C).
This is taken to imply that sulfate reducing bacteria were not involved in either initial sulfidation of the host rock or during later sulfidization that was related to the ore-forming episode. carbonate minerals, such as calcite, are quite abundant, but appear to have formed after the ore. The overall abundance of iron apparently is not systematically related to position with respect to the roll front, whereas manganese probably is concentrated near the redox interface. Titanium like iron does not show a systematic relationship to position about the roll. However, titanium is systematically more abundant in the fine fraction (462 ?m) relative to the coarse fraction with distance downdip. This reflects a progressively more intense alteration of precursor iron titanium oxide minerals to fine-grained TiO2. |
| Genre: | USGS Numbered Series |
| ProdID: | 9178 |
| Citation Author: | Goldhaber, Martin B.; Reynolds, Richard L. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | iii, 34 p. :ill. ;27 cm.; (37 p. - PGS) |
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| Citation Publisher: | U.S. Geological Survey, |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 77-821 |
| Citation Search Results Text: | Geochemical and mineralogical studies of a South Texas roll-front uranium deposit; 1977; OFR; 77-821; Goldhaber, Martin B.; Reynolds, Richard L. |
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| Citation Year: | 1977 |
| Type: | citation/reference |
| Text: | Geochemical and mineralogical studies of a South Texas roll-front uranium deposit; 1977; OFR; 77-821; Goldhaber, Martin B.; Reynolds, Richard L. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/of/1977/0821/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/of/1977/0821/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey, |
