Lawsonite metasomatism and trace element recycling in subduction zones

A. Vitale Brovarone, O. Alard, O. Beyssac, L. Martin, M. Picatto

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

Although lawsonite-bearing rocks are rare in exhumed high-pressure (HP) terranes, they are considered to exert a primary role in subduction dynamics. Recent observations in natural settings have shown that fluid-rock interaction at HP conditions, including metasomatism, may lead to unusually high lawsonite amounts even in rocks that originally contained little or no lawsonite. This process may therefore bear important implications for element recycling in subduction zones. A detailed characterization of the geochemical fingerprints associated with lawsonite metasomatism is presented in this contribution. The studied rocks belong to the HP terranes of Alpine Corsica (France), which is the largest documented exposure for lawsonite metasomatism. Metasomatic lawsonite displays complex compositional zoning, including high trace element, Cr and Ti content. The trace element content is much higher compared with the average of non-metasomatic lawsonite, and is in line with the re-incorporation of large amounts of trace elements (e.g. REE, Sr, Pb, Th) in the rock during metasomatism, as shown by mass transfer calculations. Our data suggest that serpentinites represented the main fluid source for the metasomatism, with concurrent contribution of other, possibly Ca-rich lithologies, such as mafic or meta-sedimentary rocks. We propose that the breakdown of metasomatic lawsonite may contribute to the genesis of magmas and their characteristic geochemical signatures.

Original languageEnglish
Pages (from-to)489-514
Number of pages26
JournalJournal of Metamorphic Geology
Volume32
Issue number5
DOIs
Publication statusPublished - Jun 2014
Externally publishedYes

Keywords

  • HP fluid-rock interaction
  • Lawsonite
  • Lawsonite metasomatism
  • Lawsonite-eclogite
  • Trace element recycling

Fingerprint Dive into the research topics of 'Lawsonite metasomatism and trace element recycling in subduction zones'. Together they form a unique fingerprint.

Cite this