Modelling diverse processes in the petrogenesis of a composite batholith: the Central Bohemian Pluton, Central European Hercynides

The multiple intrusions making up the Central Bohemian Pluton in the Centra l European Hercynides have petrographic and geochemical features consistent with the presence of four main granitoid suites. Major-element, trace-elem ent and Sr-Nd isotopic compositions are used to model their petrogenesis. P artial melting of metabasic locks or of a CHUR-like mantle source are inter preted to have produced melts parental to the most primitive calc-alkaline Sazava suite. Interaction of basic with more acidic magmas followed by exte nsive amphibole-plagioclase-dominated fractionation accounts for the produc tion of trondhjemites. Alternatively, the trondhjemites correspond to small -degree melts of a metabasic source. AFC (assimilation-fractional crystalli zation) modelling with a paragneiss as a contaminant and increasing D-Nd va lues simulates the characteristics of the Blatna suite. Closed-system fract ionation of strongly enriched mantle-derived magmas or their interaction wi th leucogranitic melts is deduced for the petrogenesis of the shoshonitic C ertovo bremeno suite. Partial melting of a metasedimentary source, followed by K-feldspar-dominated fractionation, accounts for the granites of rite R icany suite. The progression from relatively primitive calc-alkaline granit oids towards evolved, K-rich calc-alkaline and shoshonitic rocks is interpr eted to reflect the increasing enriched mantle input in the petrogenesis of the later suites. The evidence for Hercynian subduction is equivocal and t he mantle enrichment could have been significantly older.