Publication details
Petrogenesis of Cenozoic high-Mg (picritic) volcanic rocks in the České středohoří Mts. (Bohemian Massif, Czech Republic)
| Authors | |
|---|---|
| Year of publication | 2021 |
| Type | Article in Periodical |
| Magazine / Source | Mineralogy and Petrology |
| MU Faculty or unit | |
| Citation | |
| web | https://doi.org/10.1007/s00710-020-00729-5 |
| Doi | http://dx.doi.org/10.1007/s00710-020-00729-5 |
| Keywords | Ohře/Eger rift; Picrite; Meimechite; Basanite/tephrite; K-Ar ages; Sr-Nd-Pb isotopes |
| Description | Representative samples of high-Mg (picritic) rocks of Eocene to Oligocene age (38 to 21 Ma) from the Ceske stredohori Mts. (CSM) in the Ohre/Eger Rift were studied and compared with Cenozoic high-Mg rocks from the Bohemian Massif. The picritic rocks of the CSM correspond to picrite, meimechite and basanite to tephrite. Individual petrographic types are characterised by the association of mafic minerals: magnesian olivine (Fo(86-80)) + clinopyroxene (aluminian diopside) +/- amphibole (pargasite/kaersutite) +/- dark mica (ferroan phlogopite). The contents of incompatible elements, such as Nb, Ta, U, Th, the La-N/Yb-N ratios, and the overall Sr-Nd-Pb isotope signatures of the high-Mg rocks partly overlap the basanites of the usti Formation, also showing a similar age (44-21 Ma). The Pb isotope signature for all recognised high-Mg rock types is compatible with a variable contribution from an inherited (Variscan) orogenic Pb component preserved in their lithospheric mantle source. Both the high-Mg volcanic rocks from the CSM and from other areas of the Bohemian Massif require the involvement of a heterogenous lithospheric source. Their parental melts were generated by variable degree of melting of an olivine-rich peridotitic mantle, containing clinopyroxene-amphibole (+/- phlogopite) vein assemblages with highly radiogenic Sr and Pb signatures. |