UNIGE document Scientific Article
previous document  unige:34457  next document
add to browser collection
Title

The Altar Porphyry Cu-(Au-Mo) Deposit (Argentina): A Complex Magmatic-Hydrothermal System with Evidence of Recharge Processes

Authors
Maydagan, L.
Franchini, M.
Dilles, J.
Rey, R.
Published in Economic Geology. 2014, vol. 109, no. 3, p. 621-641
Abstract Altar (31o 29’ S, 70o 28’ W) is a large porphyry Cu-(Au-Mo) deposit with associated epithermal Au-(Ag- Cu) veins located in the Cordillera Principal of southwest San Juan province (Argentina). Altar is a complex magmatic-hydrothermal system formed from several magmatic and hydrothermal pulses during the middle- late Miocene. New LA-ICPMS U-Pb ages in zircons from the Altar porphyries indicate four discrete events of intrusions over an extended magmatic life time of ca. 3 m.y. It comprises a premineralization porphyry (11.75 ± 0.24 Ma), three mineralized porphyries (11.62 ± 0.21 and 11.68 ± 0.27 Ma, 11.13 ± 0.26 Ma, 10.35 ± 0.32 Ma) related to hydrothermal breccias, two postmineralization intrusions, and a postmineralization breccia (8.9 ± 0.4 Ma). The three mineralized porphyries (porphyries 2, 3, and 4) were emplaced within ~0.7 to 1.3 m.y. Amphibole phenocrysts from the porphyries crystallized from oxidized magmas (fO2 = NNO +1 to +2) at temperatures of 780° to 850°C and pressures between 0.9 and 1.8 kbars corresponding to depths of ~4 to 7 km. Anorthite- and Fe-rich rims in the plagioclase phenocrysts suggest that the magmatic chambers were episodically recharged by a less evolved magma. The middle-late Miocene intrusions are interpreted to have been derived from a deeper and relatively large magmatic reservoir that supplied magmas to smaller chambers located in the upper crust. The focused magmatic output to shallow levels during a period of a few million years in the Altar area has been a main requirement in the formation of this large porphyry copper deposit.
Identifiers
Full text
Structures
Research groups Isotope Geochemistry, Geochronology and Thermochronology
Mineral Resources and Geofluids
Citation
(ISO format)
MAYDAGAN, L. et al. The Altar Porphyry Cu-(Au-Mo) Deposit (Argentina): A Complex Magmatic-Hydrothermal System with Evidence of Recharge Processes. In: Economic Geology, 2014, vol. 109, n° 3, p. 621-641. https://archive-ouverte.unige.ch/unige:34457

324 hits

0 download

Update

Deposited on : 2014-02-25

Export document
Format :
Citation style :