Lithology, mineralization and alteration of the el Pachón deposit, San Juan province, Argentina
El Pachón is a porphyry copper-molybdenum deposit located at southwest of San Juan province, near the border with Chile. This deposit is hosted by a volcanic sequence of andesites and rhyolites-rhyodacites (Pachón Formation) with a Late Cretaceous-early Miocene age. This volcanic sequence is intrude...
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| Autores principales: | , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00044822_v75_n1_p39_Torres |
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| Sumario: | El Pachón is a porphyry copper-molybdenum deposit located at southwest of San Juan province, near the border with Chile. This deposit is hosted by a volcanic sequence of andesites and rhyolites-rhyodacites (Pachón Formation) with a Late Cretaceous-early Miocene age. This volcanic sequence is intruded by Miocene diorite-tonalite intrusives (Diorita Pachón), which are genetically linked to the mineralization, and by late dacitic porphyries. Petro-mineralogical studies of surface and drilling samples allow us to define alteration assemblages of typical porphyry deposits. The hydrothermal system started with a potassic stage with an assemblage of K-feldspar-biotite (quartz) with a pervasive distribution and A, EB and B veinlets with an associated ore paragenesis consisting of chalcopyrite-pyrite ± (molybdenite-bornite). During this stage, a breccia consisting of a first stage pf brecciation with quartz cement and a second stage of brecciation with a tourmaline cement was formed (Breccia South). Later on there was a phyllic stage with an assemblage of quartz-sericite-pyrite-(chlorite) with a pervasive distribution and D veinlets. The hydrothermal processes continues and is evidenced by a barren tourmaline stage that developed a breccia body (Breccia North). A propylitic alteration with an assemblage of chlorite-epidote-calcite with pervasive and in veinlets distribution developed around the phyllic halo. © 2018, Taylor and Francis Ltd. All rights reserved. |
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