Travel time of accreted igneous assemblages in western Pacific orogenic belts and their associated sedimentary rocks

Costas Xenophontos, Soichi Osozawa

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Accreted igneous assemblages in orogenic belts maybe divided into three types depending on whether they derive from seamounts, ocean ridges or subduction-related ophiolites. Seamount type basalts are associated with shallow water sediments-mostly reefoidal limestones. Ocean ridge type basalts are generally overlain by pelagic cherts. Subduction-related ophiolitic eruptives, often underlain by gabbroic and ultramafic rocks, are associated with hemipelagic mudstones. The age of such diverse eruptive lithologic assemblages reflects the time taken for them to have traveled from their locus of generation to their place of accretion at a continental margin. This relationship has been established for each type of accretionary complex, examples being taken mostly from Japan and the western Pacific rim in order to represent evolutionary processes at a typical active plate margin. In general, the seamount types are older, ridge types are of intermediate age, and the ophiolitic types are by far the youngest, usually close to zero age. Seamount type basalts are accreted by shallower scraping of the seamount's sediment apron together with fragments of seamount basalt, ridge type, by peeling due to permeability contrast, and the ophiolitic types by deeper scraping as a consequence of an inflected temperature gradient. Accordingly, it is concluded that the ophiolitic rocks are generated close to the trench and may be accreted as a result of ridge subduction.

Original languageEnglish
Pages (from-to)241-261
Number of pages21
JournalTectonophysics
Volume393
Issue number1-4 SPEC.ISS.
DOIs
Publication statusPublished - 2004 Nov 18

Keywords

  • Accretionary complex
  • Ocean ridge
  • Ophiolite
  • Ridge subduction
  • Seamount
  • Travel time

ASJC Scopus subject areas

  • Geophysics
  • Earth-Surface Processes

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