Tsujimori, Tatsuki et al. (2006) Very-low-temperature record of the subduction process: A review of worldwide lawsonite eclogites, Lithos, 92, 609-624, doi: 10.1016/j.lithos.2006.03.054. < 20100403101826904.admin > pub
  • abstract:

    Lawsonite eclogites preserve a record of very-low-temperature conditions in subduction zones. All occur at active margin settings, typically characterized by accretionary complexes lithologies and as tectonic blocks within serpentinite-matrix mélange. Peak lawsonite-eclogite facies mineral assemblages (garnet + omphacite + lawsonite + rutile) typically occur in prograde-zoned garnet porphyroblasts. Their matrix is commonly overprinted by higher-temperature epidote-bearing assemblages; greenschist- or amphibolite-facies conditions erase former lawsonite-eclogite relics. Various pseudomorphs after lawsonite occur, particularly in some blueschist/eclogite transitional facies rocks. Coesite-bearing lawsonite-eclogite xenoliths in kimberlitic pipes and lawsonite pseudomorphs in some relatively low-temperature ultrahigh-pressure eclogites are known. Using inclusion assemblages in garnet, lawsonite eclogites can be classified into two types: L-type, such as those from Guatemala and British Columbia, contain garnet porphyroblasts that grew only within the lawsonite stability field and E-type, such as from the Dominican Republic, record maximum temperature in the epidote-stability field.

    Formation and preservation of lawsonite eclogites requires cold subduction to mantle depths and rapid exhumation. The earliest occurrences of lawsonite-eclogite facies mineral assemblages are Early Paleozoic in Spitsbergen and the New England fold belt of Australia; this suggests that since the Phanerozoic, secular cooling of Earth and subduction-zone thermal structures evolved the necessary high pressure/temperature conditions. Buoyancy of serpentinite and oblique convergence with a major strike-slip component may facilitate the exhumation of lawsonite eclogites from mantle depths.

  • doi: 10.1016/j.lithos.2006.03.054
  • modified at 2020-04-16
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  • name
  • Tsujimori, Tatsuki
  • Sisson, V. B.
  • Liou, J. G.
  • Harlow, G. H.
  • Sorensen, S. S.