Southeastern Lewis Hills (Bay of Islands Ophiolite): Geology of a deeply eroded, inside-corner, ridge-transform intersection

G Suhr, Peter Anthony Cawood

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

The Lewis Hills massif (Say of Islands Ophiolite, Newfoundland) preserves a deeply eroded transform fault. A major, low-angle, extensional mylonite zone is next to the transform assemblage and probably merges laterally into it. The mylonite developed in a high-temperature environment and occurs at the top of relatively rigid lithospheric mantle. The lithospheric mantle represents exhumed, older, arc-type basement of the Little Part Complex that is also exposed across the transform in the western Lewis Hills. It differs dramatically from an asthenospheric mantle unit of the Bay of Islands Complex, exposed in the eastern Lewis Hills, that formed in a spreading ridge environment.

The fossil ridge-transform segment and associated low-angle normal fault in the Lewis Hills formed at an inside-corner structural setting similar to recently discovered core complexes at oceanic ridge-transform intersections. However, the Lewis Hills segment developed in a setting where a spreading center propagated across a transform margin and rifted older arc-type lithosphere. Factors that contributed to formation of the low-angle detachment fault are the lithospheric nature of the mantle basement, rheological weakening and strain focusing by intrusive sills, and weak lateral coupling realized by the extensional transform assemblage.

Original languageEnglish
Pages (from-to)1025-1038
Number of pages14
JournalGeological Society of America Bulletin
Volume113
Issue number8
Publication statusPublished - Aug 2001

Keywords

  • Bay of Islands Ophiolite
  • core
  • MID-ATLANTIC RIDGE
  • METAMORPHIC CORE COMPLEXES
  • FRACTURE-ZONES
  • OCEANIC-CRUST
  • WESTERN NEWFOUNDLAND
  • MAGMATIC ACCRETION
  • SPREADING CENTER
  • SEA-FLOOR
  • ORIGIN
  • LITHOSPHERE

Fingerprint

Dive into the research topics of 'Southeastern Lewis Hills (Bay of Islands Ophiolite): Geology of a deeply eroded, inside-corner, ridge-transform intersection'. Together they form a unique fingerprint.

Cite this