Mineral zoning and exhumation history in the Munchberg eclogites (Bohemia)

The zoning of clinopyroxene and garnet from the Munchberg eclogites in Northeastern Bohemia was examined using electron probe to determine their exhumation history. Zoning patterns of eclogitic minerals were interpreted by numerical modelling of Fe-Mg exchange in both concentric and aggregate arrangements. Findings show both growth zoning in the biggest grains and a 30 micron diffusion boundary layer in garnets. A multi-stage history with initial exhumation rates of more than 5 mm yr(super -1) rapidly declining in a few million years is required in the simultaneous presence of these two zoning patterns.