Porphyry-type metallization and alteration at La Florida de Nacozari, Sonora, Mexico
Journal of Research of the U.S. Geological Survey
By: Ted G. Theodore and Miguel Priego de Wit
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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.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Porphyry-type metallization and alteration at La Florida de Nacozari, Sonora, Mexico |
| Series title | Journal of Research of the U.S. Geological Survey |
| Volume | 6 |
| Issue | 1 |
| Year Published | 1978 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | Mineral Resources Program |
| Description | 14 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Journal of Research of the U.S. Geological Survey |
| First page | 59 |
| Last page | 72 |
| Country | Mexico |
| State | Sonora |
| Other Geospatial | La Florida De Nacozari |
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