U-Pb zircon and Re-Os molybdenite geochronology from La Caridad porphyry copper deposit: Insights for the duration of magmatism and mineralization in the Nacozari District, Sonora, Mexico

Victor A. Valencia, J. Ruiz, F. Barra, G. Geherls, M. Ducea, S. R. Titley, L. Ochoa-Landin

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Abstract

Uranium-lead zircon (laser ablation multi-collector ICP-MS spot analysis) ages from La Caridad porphyry copper deposit in the Nacozari District, Northeastern Sonora, Mexico, suggest a short period of magmatism, between 55.5 and 52.6 Ma. Two U-Pb ages from the mineralized quartz monzonite unit, showing different textural characteristics, yielded indistinguishable crystallization ages (∼54 Ma), and indicate that the intrusion responsible for the mineralization occurred as a single large complex unit, instead of multiple pulses of magmatism. Some zircons analyzed also show inherited ages in cores recording dates of 112-124 Ma, 141-166 Ma and 1.4 Ga. The Re-Os molybdenite ages from the potassic and phyllic hydrothermal alteration veins yielded identical ages within error, 53.6 ±0.3 Ma and 53.8±0.3 Ma, respectively (weighted average of 53.7 ±0.21 Ma), supporting a restricted period for the mineralization. The geochronological data thus indicate a short-lived magmatic and hydrothermal system. The inherited zircons of Precambrian and Late Jurassic-Mid Cretaceous age found in the intrusive rocks of La Caridad deposit, can be explained considering two possible scenarios within the tectonic/magmatic evolution of the area. The first scenario considers the presence of a Precambrian anorogenic granitic basement that is intruded by Mesozoic (Jurassic-Cretaceous) units present beneath the La Caridad deposit. The second scenario suggests that the Mesozoic Glance Conglomerate Formation of Arizona underlies the Paleocene volcanic-igneous pile in the La Caridad area.

Original languageEnglish (US)
Pages (from-to)175-191
Number of pages17
JournalMineralium Deposita
Volume40
Issue number2
DOIs
StatePublished - Mar 1 2005

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Keywords

  • La Caridad
  • Mexico
  • Porphyry Cu
  • Re-Os
  • Sonora
  • U-Pb

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Economic Geology

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