Journal of Geosciences, 55 (2010), 251–278 DOI: 10.3190/jgeosci.074 Original paper Petrology and geochemistry of the Tertiary alkaline intrusive rocks at Doupov, Doupovské hory Volcanic Complex (NW Bohemian Massif) František V. HOLUB1, *, Vladislav RAPPRICH2, Vojtěch ERBAN2, Zoltán PÉCSKAY3, Bedřich MlčOCH2, Jitka MÍKOVÁ2 1 Institute of Petrology and Structural Geology, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic;
[email protected] 2 Czech Geological Survey, Klárov 3, 118 21 Prague 1, Czech Republic 3 Institute of Nuclear Research, Hungarian Academy of Sciences, Bem tér 18/C, H-4001 Debrecen, Hungary * Corresponding author Field observations, petrography, geochemical data and the results of K–Ar dating are presented for Oligocene (c. 30–29 Ma) alkaline intrusions at the former township of Doupov (Duppau) in the central part of the Doupovské hory Volca- nic Complex (DHVC). The Doupov Intrusive Complex (DIC) is a very limited in area (< 2 km2) but is petrographically highly variable. Several phaneritic rock types have been identified, including clinopyroxenite (both the clinopyroxenite-dominated bre- ccia and xenoliths in younger intrusive phases), essexite, sodalite-bearing monzodiorite, sodalite monzosyenite to ne- pheline–sodalite syenite, and highly mafic to felsic nephelinolites (melteigite–ijolite–urtite). These rocks are accom- panied by vent breccias, and a thermal and metasomatic aureole with zones of pervasive phlogopitization. Phaneritic intrusions and their host rocks are cut by thin aphanitic dykes ranging from mafic alkaline lamprophyres to felsic tra- chytes and phonolites. All the intrusions are characterized by undersaturated alkaline compositions with high abundan- ces of incompatible elements.