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Metallogenic features of Miocene porphyry Cu and porphyry-related mineral deposits in Ecuador revealed by Re-Os, 40Ar/39Ar, and U-Pb geochronology

Barra, Fernando
Beate, Bernardo
Published in Mineralium Deposita. 2012, vol. 47, no. 4, p. 383-410
Collection Open Access - Licence nationale Springer
Abstract Mineralization and alteration events at ten Mio- cene porphyry Cu and porphyry-related epithermal mineral deposits in southern, central, and northern Ecuador were dated by means of molybdenite Re-Os, biotite and alunite 40Ar/39Ar, and titanite U-Pb geochronology. Most of these hydrothermal events show a spatio-temporal correlation with porphyry intrusion emplacement as constrained by zircon U-Pb ages. The total age range for these events spansthe 23.5–6.1 Ma period, without displaying systematic along- or across-arc age distribution trends. While epither- mal deposits tend to be spatially associated with volcanic rocks of a similar age, porphyry Cu deposits in Ecuador are frequently spatially associated with deeper-seated basement units and batholith-scale precursor intrusive systems as- sembled over ≥5 m.y. time periods. In most cases, formation of the porphyry Cu deposits is related to theyoungest magmatic (-hydrothermal) event in a given area, postdating batholith construction at a regional scale. The majority of Miocene deposits occurs in southern Ecuador where areally extensive, post-mineralization (late Miocene to recent) volcanic sequences with the potential to conceal mineralization at depth are lacking. Only few Miocene deposits occur in northern-central Ecuador, where they mainly crop out in the Western Cordillera, west of the productive present-day volcanic arc. The surface distribu- tion of post-mineralization arc volcanism reflects along-arc variations in subducting slab geometry. Porphyry Cu and epithermal deposits in Ecuador define a Miocene metal- logenic belt broadly continuous with its coeval counterpart in northern-central Peru. Although both belt segments were formed in an overall similar tectonomagmatic and metal- logenic setting, their respective metal endowments differ significantly.
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Research groups Isotope Geochemistry, Geochronology and Thermochronology
Mineral Resources and Geofluids
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SCHUTTE, Philip et al. Metallogenic features of Miocene porphyry Cu and porphyry-related mineral deposits in Ecuador revealed by Re-Os, 40Ar/39Ar, and U-Pb geochronology. In: Mineralium Deposita, 2012, vol. 47, n° 4, p. 383-410. doi: 10.1007/s00126-011-0378-z https://archive-ouverte.unige.ch/unige:19399

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Deposited on : 2012-04-16

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