The formation of the Münchberg Massif: New insights from petrology and chemistry of its serpentinite occurrences.

Serpentinization is a hydration process that forms distinct serpentine minerals depending on the pressure and temperature conditions prevailing during the fluid-rock reaction. The chemistry and petrology of serpentinite rocks provide constraints on the protolith composition and on the tectonic setting of serpentinization through insights of pressure and temperature conditions.

The Münchberg Massif is a stack of four tectonic nappes of different metamorphic grade, which were emplaced during the Variscan Orogeny. Within the lowermost Prasinit-Phyllit-Serie, several serpentinite bodies are intercalated. Understanding the formation of these serpentinites will add further insights into the tectonic development of the Münchberg Massif.

We present new petrological and chemical data of serpentinites from ten locations along the southeastern margin of the Münchberg Massif, as well as at two locations in the western region of the Massif. The samples are dominated by the serpentine minerals lizardite in the western region and antigorite along the southeastern margin. Furthermore, significant differences in the degree of serpentinization and tectonic strain were observed between the two regions. The petrological and chemical characteristics of the samples indicate distinct protolith material and serpentinization setting. We propose that the protoliths of the western and southeastern serpentinites originated from different structural positions within, or adjacent to, a subduction zone. These findings provide new constraints on the tectonic assembly and metamorphic evolution of the Münchberg Massif.