Our group members Johannes Pohlner, Afifé El Korh and Bernard Grobéty and co-workers from the universities of Bern, Geneva and Erlangen have published an article in Chemical Geology: https://www.sciencedirect.com/science/article/pii/S0009254121002965?via%3Dihub

Eclogites are high-pressure rocks that usually record a complex history of igneous formation and subsequent low-temperature interaction with water before subduction and eclogitization. The Münchberg Massif is one of the largest occurrences of eclogites in central Europe. Despite extensive study especially in the 20th century, many aspects about the origin and history of these rocks remained poorly understood. To improve this, our group created a large geochemical database, including major and trace elements and oxygen isotopes.

The eclogites show chemical characteristics of mid-ocean ridge basalts, but cannot have formed in a typical oceanic setting because the magma assimilated adjacent sediments. All eclogites are derived from a single igneous suite which diversified into plagioclase-rich cumulates and complementary basalts. Increases in Li, B, Sb and Bi concentrations coupled with a modification of the oxygen isotope compositions reveal a subsequent interaction with seawater at low temperatures. All these processes are related to the separation of microcontinents from the continental margin of Gondwana in the Cambrian and Ordovician that led to the formation of new oceans. During the Devonian high-pressure metamorphism, elements such as K, Rb, Ba and Pb were mobilized, but the total extent of high-pressure fluid-rock interactions seems limited.