Macquarie Island's Finch-Langdon fault: A ridge-transform inside corner structure

Karah L. Wertz*, Sharon Mosher, Nathan R. Daczko, Millard F. Coffin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Macquarie Island consists of uplifted oceanic crust, uniquely situated in the ocean basin where it formed, thus allowing onshore structures to be placed into their regional oceanic tectonic context. The Finch-Langdon fault, the most significant spreading-related structure on the island, juxtaposes upper-crust rocks against lower-crust and upper-mantle rocks. It consists of dominantly oblique strike-slip, northwest-, west-northwest-, and north-northeast-striking fault segments that bear hydrothermal mineralization indicative of faulting during seafloor spreading. Talus breccias and graywackes overlain by volcanic flows proximal to the fault indicate a long-lived submarine fault scarp that exposed diabase dikes and gabbros during volcanism. Swath reflectivity and bathymetry reveal ridge-parallel spreading fabric and perpendicular fracture zones, the closest -e17 km east of the island. On the basis of field and swath data, we propose that this fault zone formed near the inside corner of a ridge-transform intersection and that structures on the island are conformable with those in the surrounding seafloor.

Original languageEnglish
Pages (from-to)661-664
Number of pages4
JournalGeology
Volume31
Issue number8
DOIs
Publication statusPublished - Aug 2003
Externally publishedYes

Keywords

  • Macquarie Island
  • Ocean crust
  • Ophiolite
  • Spreading center
  • Transform

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