Dynamics of intraoceanic subduction initiation: 1. Oceanic detachment fault inversion and the formation of supra-subduction zone ophiolites

Research output: Contribution to journalArticlepeer-review

Authors

  • Cedric Thieulot
  • Douwe J J van Hinsbergen
  • Antony Morris
  • Oliver Plümper
  • Wim Spakman

Colleges, School and Institutes

Abstract

Subduction initiation is a critical link in the plate tectonic cycle. Intraoceanic subduction zones can form along transform faults and fracture zones, but how subduction nucleates parallel to mid-ocean ridges, as in e.g., the Neotethys Ocean during the Jurassic, remains a matter of debate. In recent years, extensional detachment faults have been widely documented adjacent to slow-spreading and ultraslow-spreading ridges where they cut across the oceanic lithosphere. These structures are extremely weak due to widespread occurrence of serpentine and talc resulting from hydrothermal alteration, and can therefore effectively localize deformation. Here, we show geochemical, tectonic, and paleomagnetic evidence from the Jurassic ophiolites of Albania and Greece for a subduction zone formed in the western Neotethys parallel to a spreading ridge along an oceanic detachment fault. With 2-D numerical modeling exploring the evolution of a detachment-ridge system experiencing compression, we show that serpentinized detachments are always weaker than spreading ridges. We conclude that, owing to their extreme weakness, oceanic detachments can effectively localize deformation under perpendicular far-field forcing, providing ideal conditions to nucleate new subduction zones parallel and close to (or at) spreading ridges. Direct implication of this, is that resumed magmatic activity in the forearc during subduction initiation can yield widespread accretion of suprasubduction zone ophiolites at or close to the paleoridge. Our new model casts the enigmatic origin of regionally extensive ophiolite belts in a novel geodynamic context, and calls for future research on three-dimensional modeling of subduction initiation and how upper plate extension is associated with that.

Details

Original languageEnglish
Pages (from-to)1753-1770
Number of pages18
JournalGeochemistry Geophysics Geosystems
Volume16
Issue number6
Early online date21 May 2015
Publication statusPublished - Jun 2015

Keywords

  • Neotethys, Numerical modeling, Oceanic core complex, Plate tectonics, Serpentinization

ASJC Scopus subject areas