The southwestern edge of the Ryukyu subduction zone

A high Q mantle wedge

Yen Ting Ko, Ban Yuan Kuo*, Kuo Lung Wang, Shu Chuan Lin, Shu Huei Hung

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The lateral edge of a subduction zone is usually depicted as an opening to the asthenosphere where invigorated dynamics and amplified magmatism take place. In this study we present evidence from seismic data suggesting the presence of a cold and dynamically sluggish edge environment at the southwest end of the Ryukyu subduction system. We measured attenuation, or 1/. Q, for P waves from subduction zone events at ~100. km depths received by OBSs in the Okinawa trough and land stations in NE Taiwan. In the Okinawa trough 100-200. km from the edge, Q values are lower than 100. In the vicinity of the edge, Q values increase from 100 to over 1000 towards Taiwan. To reconcile arguments from geophysical and geochemical observations, we propose that the mantle wedge near the edge has high Q values due to low temperatures and probably low water content. These may result from coupling of the slab laterally with the thick Eurasian lithosphere, which inhibits back-arc rifting, retards subduction, and reduces the water supply to the mantle wedge. The SW Ryukyu subduction system represents a subduction-zone edge type distinct from more commonly documented free or warm edges.

Original languageEnglish
Pages (from-to)145-153
Number of pages9
JournalEarth and Planetary Science Letters
Volume335-336
DOIs
Publication statusPublished - 15 Jun 2012
Externally publishedYes

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Keywords

  • Mantle wedge
  • Seismic attenuation
  • Slab edge
  • Subduction zone

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