Disequilibrium garnet growth in eclogitic rocks: an example from the southern Motagua fault zone, Guatemala

Abstract

Exceptionally well-preserved lawsonite eclogite occurs in the southern Motagua fault zone, Guatemala. Texturally homogeneous lawsonite eclogite occurs as meter-scale blocks in serpentinite, and is well suited for phase-equilibrium analyses such as pseudosection modelling. In contrast, evidence for disequilibrium garnet crystallization is common in quartz-rich pressure shadows around eclogite boudins in metasedimentary rocks. Garnet in such domains shows a considerable variation in compositional zoning from grain to grain, and some grains show sector and reverse zoning.