6533b821fe1ef96bd127b827

RESEARCH PRODUCT

Age and origin of the Böllsteiner Odenwald

subject

description

The granitoid protoliths of the gneisses of the Bollsteiner Odenwald, a part of the Mid German Crystalline Rise, intruded at 405 ± 3 Ma. This age was obtained by single zircon 207Pb/206Pb evaporation measurements. It is supported by an upper discordia intercept age of 410 ± 11 Ma from single zircon U/Pb data. These granitoids were derived from hybrid magmas according to their geochemical characteristics. Inherited zircon grains with apparent ages of 882 and 1138 Ma further constrain the source heterogeneity. The isotope data with Nd model ages for the granitoid gneisses between 1.3 and 1.7 Ga also underline the involvement of Proterozoic material into the magma sources. Since the geochemical data indicate a subduction zone environment we suggest that the Bollsteiner Odenwald was formed as part of a Silurian/Early Devonian magmatic arc in an active continental margin. The age data imply that the Bollsteiner Odenwald is closely related to the Spessart and Ruhla Crystalline Complexes but not to the Bergstrasser Odenwald. Therefore the Otzberg zone is considered to be a Variscan suture zone.