Tertiary alkaline Roztoky Intrusive Complex, České středohoří Mts., Czech Republic: petrogenetic characteristics

0399310 - GLÚ 2015 RIV DE eng J - Journal Article
Skála, Roman - Ulrych, Jaromír - Ackerman, Lukáš - Jelínek, E. - Dostal, J. - Hegner, E. - Řanda, Zdeněk
Tertiary alkaline Roztoky Intrusive Complex, České středohoří Mts., Czech Republic: petrogenetic characteristics.
International Journal of Earth Sciences. Roč. 103, č. 5 (2014), s. 1233-1262. ISSN 1437-3254. E-ISSN 1437-3262
R&D Projects: GA AV ČR IAA300130902
Institutional support: RVO:67985831 ; RVO:61389005
Keywords : Bohemian Massif * Cenozoic * continental rift * Roztoky Intrusive Complex * alkaline intrusions * geochemistry
Subject RIV: DD - Geochemistry
Impact factor: 2.093, year: 2014

The České středohoří Mts. is the dominant volcanic center of the Ohře (Eger) rift zone. It hosts the Roztoky Intrusive Complex (RIC), which is made up of a caldera vent and intrusions of 33–28-Ma-old hypabyssal bodies of essexite–monzodiorite–sodalite syenite series accompanied by a radially oriented 30–25-Ma-old dike swarm comprising about 1,000 dikes. The hypabyssal rocks are mildly alkaline mostly foid-bearing types of mafic to intermediate compositions. The dike swarm consists of chemically mildly alkaline and rare strongly alkaline rocks (tinguaites). The geochemical signatures of the mildly alkaline hypabyssal and associated dike rocks of the RIC are consistent with HIMU mantle sources and contributions from lithospheric mantle. The compositional variations of essexite and monzodiorite can be best explained by fractional crystallization of parent magma without significant contributions of crustal material. On the other hand, the composition of monzosyenite, leuco-monzodiorite and sodalite syenite reflects fractional crystallization coupled with variable degrees of crustal assimilation. It is suggested that the parent magmas in the Ohře rift were produced by an adiabatic decompression melting of ambient upper mantle in response to lithospheric extension associated with the Alpine Orogeny.
Permanent Link: http://hdl.handle.net/11104/0226629