Economic Geology; January 2005; v. 100; no. 1;
p. 87-114; DOI: 10.2113/100.1.0087
© Society of Economic Geologists
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FIG. 15. Simplified schematic cross sections, showing the geomorphologic
setting and age of supergene mineralization in selected profiles from the
porphyry copper belt of southern Perú. Toquepala and Cerro Verde exhibit
complex profiles with multiple chalcocite horizons, reflecting polystage
histories of leaching, oxidation, and enrichment. Alunite group mineral dates in
the Cerro Verde deposit and Angostura and Posco prospects indicate that
supergene activity began in the late Eocene beneath a regional, subplanar
topography. Late Oligocene supergene activity is recorded in the Cerro
Verde-Santa Rosa district and the La Llave prospect beneath the La Caldera
surface, a correlative of the 24 Ma Altos de Camilaca surface, which is
considered to have controlled late Oligocene leaching and enrichment in the
Cuajone-Toquepala district. Deepening of supergene profiles during the early
Miocene is considered to have been controlled by the Pampa Lagunas pediplain and
its correlatives. The development of the Multiple Pediment stage eroded
preexisting profiles over wide areas but was responsible for continued supergene
activity at the Cerro Verde and Toquepala deposits, prior to the onset of
hyperaridity in the late Miocene.
Copyright © 2008 by Society of Economic Geologists
