Zircon crystallization and the lifetimes of ore-forming magmatic-hydrothermal systems

Magmatic-hydrothermal copper ore formation involves multiple pulses of subvolcanic porphyry intrusion, vein opening, and hydrothermal ore deposition. It is driven by larger subjacent magma reservoirs, acting as the source of fluid and ore-forming components. High-precision U-Pb ages of individual zi...

Full description

Saved in:
Bibliographic Details
Published in:Geology (Boulder) 2011-08, Vol.39 (8), p.731-734
Main Authors: von Quadt, Albrecht, Erni, Michaela, Martinek, Klara, Moll, Melanie, Peytcheva, Irena, Heinrich, Christoph A
Format: Article
Language:English
Subjects:
absolute age
Alumbrera Mine
Argentina
Bingham mining district
Bingham Utah
case studies
Catamarca Argentina
Copper
copper ores
crystal growth
Crystallization
Economic geology
Geochronology
Geology
gold ores
hydrothermal conditions
igneous rocks
intrusions
Magma
magma chambers
magmas
magmatism
metal ores
metallogeny
mineral deposits, genesis
mineralization
nesosilicates
ore-forming fluids
orthosilicates
porphyry
porphyry copper
porphyry gold
Salt Lake County Utah
silicates
South America
Studies
U/Pb
United States
Utah
volcanic rocks
zircon
zircon group
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Magmatic-hydrothermal copper ore formation involves multiple pulses of subvolcanic porphyry intrusion, vein opening, and hydrothermal ore deposition. It is driven by larger subjacent magma reservoirs, acting as the source of fluid and ore-forming components. High-precision U-Pb ages of individual zircon crystals from porphyries immediately predating and postdating Cu-Au mineralization at Bingham Canyon (Utah, United States) and Bajo de la Alumbrera (northwestern Argentina) show a significant spread of reliably concordant ages. This demonstrates zircon crystal formation over a protracted period of ∼1 m.y., which is interpreted to record the lifetime of the magma reservoir from which porphyries and ore fluids were extracted. The youngest zircons in all pre-ore and post-ore intrusions overlap within a much shorter time interval of 0.32 m.y. at Bingham Canyon and 0.090 m.y. at Alumbrera; these youngest zircons of each intrusion are interpreted to bracket the maximum duration of porphyry emplacement and ore formation to short periods, consistent with thermal constraints. This study illustrates that age brackets based on individual magmatic zircon grains are geologically more informative than the calculation of means and standard deviations based on apparently normal age distributions in zircon populations.
ISSN:0091-7613
1943-2682
DOI:10.1130/G31966.1