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Recurrent Cenozoic volcanic activity in the Bohemian Massif (Czech Republic)

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ULRYCH Jaromír DOSTAL Jaroslav ADAMOVIČ Jiří JELÍNEK Emil ŠPAČEK Petr HEGNER Ernst BALOGH Kadosa

Rok publikování 2011
Druh Článek v odborném periodiku
Časopis / Zdroj Lithos
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Doi http://dx.doi.org/10.1016/j.lithos.2010.12.008
Obor Geologie a mineralogie
Klíčová slova Bohemian Massif; Cenozoic; Alkaline volcanism; Paleostress fields; Rift Mantle
Popis Cenozoic anorogenic volcanism of the Bohemian Massif is an integral part of the Central European Volcanic Province. The temporal and spatial distribution of volcanic rocks in the Bohemian Massif, their geochemistry and mineralogy as well as their tectonic setting and paleostress data are used to characterize and classify this volcanic activity. Three main volcanic periods can be distinguished based on K–Ar data and known paleostress fields: (i) pre-rift (79–49 Ma), (ii) syn-rift (42–16 Ma) and (iii) late-rift (16–0.3 Ma), with the youngest period further subdivided into three episodes. The dominant mafic rock types (N7 wt.% MgO) of all periods are of nephelinite–basanite/tephrite composition. The exceptions are suites of melilitic ultramafic rocks of the pre-rift period in northern Bohemia and of the final episode of the late-rift period in western Bohemia. The most voluminous are volcanic rocks of the syn-rift period occurring in the Ohře Rift Graben. The initial 87Sr/86Sr (0.7032 to 0.7050) and 143Nd/144Nd (0.51264 to 0.51301) ratios of the mafic volcanic rocks of the Bohemian Massif are characteristic of magmas derived from a sub-lithospheric mantle source. The isotopic ratios resemble those of the HIMU mantle source (206Pb/204Pb ca. 19 to 20). These rocks have themost isotopically depleted compositions among the Central European Volcanic Province volcanics.