Contributions to Mineralogy and Petrology

, Volume 144, Issue 3, pp 347–364

Relative oxidation states of magmas inferred from Ce(IV)/Ce(III) in zircon: application to porphyry copper deposits of northern Chile

  • Julian R. Ballard
  • Michael J. Palin
  • Ian H. Campbell
Original Paper

DOI: 10.1007/s00410-002-0402-5

Cite this article as:
Ballard, J.R., Palin, M.J. & Campbell, I.H. Contrib Mineral Petrol (2002) 144: 347. doi:10.1007/s00410-002-0402-5

Abstract.

Major- and trace-element compositions of zircons and whole rocks from 14 barren and seven ore-bearing calc-alkaline intrusions from the Chuquicamata-El Abra porphyry copper belt of northern Chile have been measured in situ by excimer laser ablation (ELA) ICP-MS. These data permit the Ce(IV)/Ce(III) ratio within zircon to be calculated using a lattice-strain model for mineral-melt partitioning of Ce(IV) and Ce(III). Zircon Ce(IV)/Ce(III) and EuN/EuN* ratios, and by inference magmatic oxidation states, generally increase from older, mafic to younger, felsic units. Within this sequence, porphyry copper mineralization is directly associated only with intrusions with zircon Ce(IV)/Ce(III)>300 and EuN/EuN*>0.4. Such trends can be understood in terms of interdependent relations between oxygen fugacity, sulfur speciation and solubility, and chalcophile element partitioning in silicate magmas. Because zircon occurs in most calc-alkaline intrusions and is resistant to subsolidus alteration, zircon Ce(IV)/Ce(III) ratios provide a useful tool for evaluating the economic potential of such rocks for magmatic-hydrothermal Cu±Au mineralization. The approach is general and may provide a means to infer relative oxidation state in a wide range of intermediate to felsic igneous rocks.

Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Julian R. Ballard
    • 1
  • Michael J. Palin
    • 1
  • Ian H. Campbell
    • 1
  1. 1.Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia
  2. 2.Present address: Department of Geology, University of Otago, Dunedin 9001, New Zealand

Personalised recommendations