Base-up growth of ocean crust by multiple phases of magmatism: field evidence from Macquarie Island

A H Dijkstra, Peter Anthony Cawood

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Macquarie Island preserves largely in-situ Miocene oceanic crust and mantle formed at a slow-spreading ridge. The crustal section on the island does not conform to a simple 'layer cake pseudo-stratigraphy', but is the result of multiple magmatic episodes. Macquarie Island crust did not grow by top-down cooling, but rather from the base up. Peridotites cooled first and formed the basement into which gabbro plutons were intruded. This was followed by cooling and deformation, and by intrusion of dykes that fed a sheeted dyke-basalt complex. Finally, lava-filled grabens were formed. These relative age relations rule out simple cogenetic relations between rock units.

Original languageEnglish
Pages (from-to)739-742
Number of pages4
JournalJournal of the Geological Society
Volume161
Publication statusPublished - Sept 2004

Keywords

  • Macquarie Island
  • ophiolites
  • mid-ocean ridges
  • sheeted dykes
  • oceanic lithosphere
  • SW PACIFIC
  • SEA-FLOOR
  • BOUNDARY
  • RIDGES
  • OPHIOLITE
  • EVOLUTION

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