Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Geochemistry and petrogenesis of the Klatovy and Kozlovice granodiorites - SW part of the Central Bohemian Plutonic Complex
Abstract
The Klatovy apophysis in the south-westernmost part of the Central Bohemian Plutonic Complex (CBPC) is built mainly by granitoids of the Klatovy and Kozlovice intrusions. These differ strongly in terms of their field occurence, petrology and geochemical character (major- and trace-element contents as well as radiogenic and stable isotope data). The Klatovy granodiorite shows 87Sr/86Sr350 between 0.708 and 0.709, and this, together with its major- and trace-element composition, is characteristic for the high-K calc-alkaline group of the CBPC. Whole-rock Ű18O values are low (+6.8 to +7.2 %. SMOW), likewise in magmas with major mantle component. The abundant mafic microgranular enclaves display evidence pointing to their hybrid origin and this, together with the observed whole-rock geochemical variations, implies an important role for hybridization (H-type) in the genesis of the Klatovy intrusion. (Muscovite-) biotite Kozlovice granodiorite (with cordierite in places), is a peraluminous rock (A/CNK = 1.1-1.2; up to 1.8). Two initial Sr isotopic ratios are nearly the same (87Sr/86Sr350 = 0.714), corresponding to mature upper crust. Likewise, the whole-rock Ű18O values are higher (+8.4 %.) than those obtained for the Klatovy intrusion. The Kozlovice granodiorite seems to be a product of anatexis of mature (meta-) sedimentary rocks (S-type) geochemically similar to typical Moldanubian paragneisses.
