UNIGE document Scientific Article
previous document  unige:45890  next document
add to browser collection
Title

Reported supergene sphalerite rims at the Chuquicamata porphyry deposit (northern Chile) revisited: Evidence for a hypogene origin

Authors
Zentilli, M.
Published in Economic Geology. 2015, vol. 110, no. 1, p. 253-262
Abstract Previous studies attributed a supergene origin to sphalerite rimming copper minerals occurring in Chuquicamata in a mineral assemblage including typically chalcocite-digenite (Cu1.85S1.12 and u1.99S1.01), covellite(CuS and Cu1.08S0.92), and sphalerite (up to 1.2 wt % Fe). Microscopic observations on samples from a central and a southern section, completed by scanning electronic microscope (SEM) backscattering electron imaging and electron microprobe analyses, suggest that all sphalerite in Chuquicamata is hypogene. A scenario, backed by observations in each step, that explains the formation of the peculiar “sphalerite rims” is the following: (1) precipitation of chalcopyrite, typical of the early and main hydrothermal stages; (2) precipitation of sphalerite rimming chalcopyrite and in voids and in weakness sites during the late hydrothermal stage; (3) partial or total replacement of chalcopyrite by chalcocite-digenite during the late hydrothermal stage; and (4) formation of lamellar covellite, principally at the expense of chalcopyrite, suggesting increasingly oxidizing and/or acidic conditions. This covellite may be linked to supergene processes and/or to the late hydrothermal stage. The findings of the present work have implications for the position of the lower limit of the supergene enrichment in the eastern-southern part of the deposit, as the sphalerite rims, now interpreted as hypogene, were the only potential supergene sulfide in the eastern vertical section of the southern section.
Keywords SphaleritePorphyryChuquicamata
Identifiers
Full text
Structures
Research group Mineral Resources and Geofluids
Project FNS: 129988
Citation
(ISO format)
PINGET, Marie-Caroline et al. Reported supergene sphalerite rims at the Chuquicamata porphyry deposit (northern Chile) revisited: Evidence for a hypogene origin. In: Economic Geology, 2015, vol. 110, n° 1, p. 253-262. https://archive-ouverte.unige.ch/unige:45890

312 hits

3 downloads

Update

Deposited on : 2015-01-27

Export document
Format :
Citation style :