The influence of thermal differences and variation of Cl–F–OH ratios on Cu-Ni-PGE mineralization in the contact aureole of the south Kawishiwi intrusion, Duluth complex

Zsolt Benkó, Aberra Mogessie, Ferenc Molnár, Steven A. Hauck, Mark J. Severson, Karl Ettinger

Research output: Contribution to journalArticle

Abstract

In the contact metamorphic aureole of the Duluth Complex, Cu-Ni-PGE mineralization occurs locally up to 100 m from the intrusion-footwall contact (Spruce Road area), whereas elsewhere (Dunka Pit deposit) the footwall granite and metapelite (Serpentine deposit) are barren. This study aimed to understand the effect of temperature and halogen fugacity variations on the presence or absence of mineralization in these footwall units. The mafic mineral assemblages, two-pyroxene, titanium-in-quartz, and biotite-apatite thermometers indicate that temperatures could be as high as 920 C in the mineralized areas of the footwall, whereas the maximum temperature was lower by about 100 C in the unmineralized part of the intrusion. Variation of the halogen concentrations and fugacities was monitored with the analysis of halogen concentrations in biotite and apatite. Fluorine and chlorine concentrations in biotite increase as a function of the distance from contact in the mineralized drill core and decrease in the unmineralized zones. Chlorine concentrations in apatite increase parallel with the distance from contact in the mineralized zones, whereas fluorine concentrations show only minor variation. Concentrations of these elements may have had subtle effect on the partial melting in the footwall units and indirectly facilitated the infiltration of the sulfide liquid into the footwall.

Original languageEnglish
Article number474
JournalGeosciences (Switzerland)
Volume8
Issue number12
DOIs
Publication statusPublished - Dec 2018

Keywords

  • Contact metamorphism
  • Cu-Ni-PGE mineralization
  • Duluth Complex
  • Halogen fugacity
  • South Kawishiwi intrusion
  • Titanium-in-quartz thermometry
  • Two-pyroxene thermometry

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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