Petrogenesis of Cenozoic high-Mg (picritic) volcanic rocks in the České středohoří Mts. (Bohemian Massif, Czech Republic)
| Autor: | Emil Jelínek, Jaromír Ulrych, Lukáš Krmíček, Simona Krmíčková, Roman Skála, Zuzana Korbelová, Kadosa Balogh |
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| Rok vydání: | 2021 |
| Předmět: |
geography
geography.geographical_feature_category Olivine 020209 energy Pargasite Geochemistry 02 engineering and technology Massif engineering.material 010502 geochemistry & geophysics 01 natural sciences Volcanic rock Geophysics Geochemistry and Petrology Tephrite 0202 electrical engineering electronic engineering information engineering engineering Phlogopite Kaersutite Geology 0105 earth and related environmental sciences Petrogenesis |
| Zdroj: | Mineralogy and Petrology. 115:193-211 |
| ISSN: | 1438-1168 0930-0708 |
| DOI: | 10.1007/s00710-020-00729-5 |
| Popis: | Representative samples of high-Mg (picritic) rocks of Eocene to Oligocene age (38 to 21 Ma) from the Ceske středohoři Mts. (CSM) in the Ohře/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 (Fo86–80) + clinopyroxene (aluminian diopside) ± amphibole (pargasite/kaersutite) ± dark mica (ferroan phlogopite). The contents of incompatible elements, such as Nb, Ta, U, Th, the LaN/YbN 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. |
| Databáze: | OpenAIRE |
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