Petrological analysis of the serpentinization process in the Münchberg Massif, Northern Bavaria

Among the search for naturally occurring hydrogen, serpentinization was identified as an important hydrogen producing process. As such, understanding of the formation history of typical serpentinite occurrences is critical. The Münchberg Massif in northeast Bavaria in Germany contains serpentinite bodies in the lowermost unit, namely the Prasinite-Phyllite-Series. Several of the bodies are exposed because of uplift and denudation of the Münchberg Massif. Study of these serpentenites and their geological context can give important insights into the serpentinization process. Serpentinite samples were taken at the locations of Peterleinstein and Zell, situated about 20 km from each other. Petrological analyses were carried out on the recovered samples. Samples from Peterleinstein are completely serpentinized and the serpentine has a platy structure. In samples from Zell, mesh serpentine is present together with numerous orthopyroxene and olivine relicts. The chemical analyses point to a rather harzburgitic to dunitic protolith for both locations, suggesting a depleted mantle source. However, the serpentinite at Peterleinstein is enriched in light rare earth elements and depleted in heavy rare earth elements compared to the serpentinite from Zell. This could be explained by mantle heterogeneities. The petrological and chemical differences between the studied locations show that the process of serpentinization is complex and variable. Therefore, in depth study of this process is imperative for the exploration of naturally occurring hydrogen.