Ultrapotassic plutonic rocks of the Chotělice Intrusive Complex in the basement of the Bohemian Cretaceous Basin, Eastern Bohemia
Abstract
Ultrapotassic melasyenites (similar to shonkinites), monzonites to monzogabbros and cumulitic phlogopite clinopyroxenites of the Chotělice Intrusive Complex in E Bohemia are rocks petrographically and geochemically different from abundant ultrapotassic plutonites (namely durbachites) of the Moldanubian Zone. Chotělice melasyenites are weakly nepheline-normative, more oxidized, higher in CaO and Sr and lacking any Eu-anomaly in contrast with nature of hypersthene-normative, CaO and Sr poor durbachitic rocks typically displaying a negative Eu-anomaly.
These compositional differences are interpreted in terms of distinct compositional characteristics and tectonic histories of lithospheric mantle sources of Variscan ultrapotassic magmas beneath at least a part of the Bohemicum and the Moldanubian Zone of the Bohemian Massif.