Why is lawsonite eclogite so rare? Metamorphism and preservation of lawsonite eclogite, Sivrihisar, Turkey

Donna L. Whitney, Peter B. Davis

Research output: Contribution to journalArticlepeer-review

92 Scopus citations

Abstract

A rare occurrence of lawsonite eclogite crops out in a belt of high-pressure rocks in the Sivrihisar Massif, Turkey. Although lawsonite eclogite is predicted to be common at depths of ∼45-300 km in subduction zones, lawsonite seldom survives exhumation. In the Sivrihisar Massif, lawsonite eclogite occurs as 5-cm-long to 3.5-m-long pods in lawsonite blueschist and blueschist facies quartzite and marble. We have identified >70 eclogite pods within an ∼14 km2 area; most of them are lawsonite bearing. Phase diagrams calculated for Sivrihisar eclogite bulk compositions indicate metamorphic conditions of 21-24 kbar, ∼422-580 °C. High-pressure minerals (omphacite, lawsonite) are synkinematic with respect to the main fabric, and therefore preserve chemical and structural features of high-pressure subduction metamorphism. The presence of both pristine and retrogressed lawsonite eclogite within meters of each other suggests that lawsonite eclogite preservation is related to rapid exhumation and other factors. For example, the effects of exhumation-related deformation ± fluid infiltration may locally overprint some rocks, producing clinozoisite and/or epidote, whereas rocks that escape these effects retain primary lawsonite.

Original languageEnglish (US)
Pages (from-to)473-476
Number of pages4
JournalGeology
Volume34
Issue number6
DOIs
StatePublished - Jun 1 2006

Keywords

  • Eclogite
  • Exhumation
  • Lawsonite
  • Subduction metamorphism
  • Turkey

Fingerprint

Dive into the research topics of 'Why is lawsonite eclogite so rare? Metamorphism and preservation of lawsonite eclogite, Sivrihisar, Turkey'. Together they form a unique fingerprint.

Cite this