Alkaline subvolcanic rocks of České středohoří Mts. compared to those of Kaiserstuhl (Germany) and Monteregian Hills (Canada): petrological-geochemical study
Abstract
The Roztoky Intrusive Centre (RIC) represents a complicated multiple intrusive structure combining large elliptical crater vent (3 km by 1.5 km) filled by products of superficial trachytic and minor basaltic volcanism with trachytic and phonolitic intrusions, accompanied by hypabyssal ntrusions of trachybasaltic (essexite, monzodiorite) and syenitic character (sodalite syenite), as well as a radial dyke swarm of amprophyres, semilamprophyres and felsic derivatives. Magmatic activity of a deeply eroded central part of the intrusive centre is dated as 33 - 28 Ma; associated dyke derivatives are dated as up to 24 Ma old.
Geochemical characteristics of the evolved subvolcanic essexite - monzodiorite - sodalite syenite - differenciated (semi)lamprophyre / felsic derivative suite corresponds to the trachybasalt - basaltic trachyandesite effusive suite of the Děčín Formation in the České středohoří Mts. The geochemic and Sr-Nd isotopic signatures of the RIC rock suite confirm its mantle origin.