| Abstract: | Pervasive secondary biotite-rich mineral assemblages, characteristic of potassic alteration found in the cores of most commercial porphyry copper systems, are associated spatially with a conspicuous color and a geochemical anomaly at La Florida de Nacozari, Sonora. These composite biotite-magnetite assemblages, with or without actinolite, quartz, rutile, sphene, chalcopyrite, and pyrite assemblages, are primarily the result of early dispersed biotitic (EDB) alteration of andesite. The bulk of the near-surface copper in the area, however, was introduced later by the veins that cut the EDB-altered andesite. These late veins are distinguished by a quartz-calcite-chlorite±laumontite±chalcopyrite assemblage, and the chalcopyrite in these veins may reflect upward remobilization of deep EDB copper by fluids associated with the emplacement of nearby coarse-grained granite. Fluid-inclusion relations in the late veins suggest that their fluids were nonboiling and relatively dilute. |
| Genre: | Article |
| ProdID: | 70043397 |
| Citation Author: | Theodore, Ted G.; Priego de Wit, Miguel |
| Citation Contributing Office: | Mineral Resources Program |
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| Citation End Page: | 72 |
| Citation Issue: | 1 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Research of the U.S. Geological Survey |
| Citation LatN: | 32.49 |
| Citation LatS: | 26.3 |
| Citation LonE: | -108.42 |
| Citation LonW: | -115.05 |
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| Citation Online Only Flag: | |
| Citation Phsyical Description: | 14 p. |
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| Citation Public Comments: | |
| Citation Publisher: | U.S. Geological Survey |
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| Citation Search Results Text: | Porphyry-type metallization and alteration at La Florida de Nacozari, Sonora, Mexico; 1978; Article; Journal; Journal of Research of the U.S. Geological Survey; Theodore, Ted G.; Priego de Wit, Miguel |
| Citation Start Page: | 59 |
| Citation Volume: | 6 |
| Citation Year: | 1978 |
| Type: | citation/reference |
| Text: | Porphyry-type metallization and alteration at La Florida de Nacozari, Sonora, Mexico; 1978; Article; Journal; Journal of Research of the U.S. Geological Survey; Theodore, Ted G.; Priego de Wit, Miguel |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/journal/1978/vol6issue1/report.pdf |
| Date Other: | Tue, 1 Jan 2013 00:00 -0600 |
| Publisher: | U.S. Geological Survey |
| Superseded by: |
http://pubs.er.usgs.gov/publication/ofr76760
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