Contrasting eclogite-facies metamorphism in the NW Bohemian Massif

Abstract

Eclogite-facies metamorphism occurs within two distinct settings within the NW of the Bohemian Massif, the easternmost of the European Variscides. Relict eclogite boudins occur within the widespread migmatitic amphibolite to amphibolite of the Marianské Lažné Complex (MLC), a triangle shaped body occupying the Devonian sututre zone between the lower (Saxothuringian Domain) and upper (Teplá-Barrandian and Moldanubian domains) plates. The eclogite from the MLC records a strong metam overprint reaching granulite-facies conditions and shows mid-Devonian metamorphic ages. In contrast eclogite bodies occur as lenses or boudins in orthogneiss in high-grade nappes thrust over the Saxothuringian (lower plate) Domain. The Saxothuringian eclogites are younger (Late-Devonian to Early-Carboniferous) and record upto UHP (diamond-bearing) conditions. Microstructural study of omphacite in the Saxothuringian eclogite reveals a transition from constrictional to flattening strain that is thought to represent stretching, break-off, and rebound of the downgoing plate. This talk introduces the bimodal eclogite-facies metamorphism in the NW Bohemian massif and discusses future directions in order to develop a complete geodynamic model for the region.

Date
Event
Seminars on Orogenic Processes
Location
Salle de réunion, 1 rue Blessig, Université de Strasbourg