Tectonic setting of porphyry Cu-Au mineralisation in the Ordovician - Early Silurian Macquarie Arc, Eastern Lachlan Orogen, New South Wales

R. A. Glen*, A. J. Crawford, D. R. Cooke

*Corresponding author for this work

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Available age data enable the recognition of four groups of porphyries that were emplaced during the ∼ 50 million year punctuated history of the earliest Ordovician to earliest Silurian intra-oceanic Macquarie Arc in the Eastern subprovince of the Lachlan Orogen. These porphyries were not emplaced during steady-state subduction. Porphyry groups 1-3 formed during critical events in the evolution of the arc related to interruptions and resumptions of arc activity. They are pre-accretionary in character, in that they formed in the arc that for most of the Ordovician lay on the Gondwana Plate, above a west-dipping subduction zone, and separated from the Gondwana margin by the Wagga Basin. In contrast, Group 4 porphyries are syn-accretionary and were emplaced into tilted and deformed volcanic and volcaniclastic packages during an extension or relaxation event in the multiphase Early Silurian Benambran Orogeny, attributed to the accretion of the arc and collapse of the former backarc basin. The Lachlan Transverse Zone is a major arc-normal corridor that favoured emplacement of many porphyries commonly, but not exclusively, shoshonitic in chemistry. All porphyry groups are potentially mineralised, with Groups 3 and 4 known to contain world-class Cu-Au deposits.

Original languageEnglish
Pages (from-to)465-479
Number of pages15
JournalAustralian Journal of Earth Sciences
Volume54
Issue number2-3
DOIs
Publication statusPublished - Mar 2007
Externally publishedYes

Keywords

  • Lachlan Orogen
  • Macquarie Arc
  • Ordovician
  • Porphyry copper gold deposits
  • Silurian

Fingerprint Dive into the research topics of 'Tectonic setting of porphyry Cu-Au mineralisation in the Ordovician - Early Silurian Macquarie Arc, Eastern Lachlan Orogen, New South Wales'. Together they form a unique fingerprint.

Cite this