Chemie der Erde 73 (2013) 429–450 Contents lists available at ScienceDirect Chemie der Erde jou rn al homepage: www.elsevier.de/chemer Plio-Pleistocene basanitic and melilititic series of the Bohemian Massif: K-Ar ages, major/trace element and Sr–Nd isotopic data Jaromír Ulrych a , Lukᡠs Ackerman a,∗ , Kadosa Balogh b , Ernst Hegner c , Emil Jelínek d , Zoltan Pécskay b , Antonín Pˇ richystal e , Brian G.J. Upton f , Jiˇ rí Zimák g , Radana Folt ´ ynová e a Institute of Geology, v.v.i., Academy of Sciences of the Czech Republic, Rozvojová 269, 165 00 Praha 6, Czech Republic b Institute of Nuclear Research, Hungarian Academy of Sciences, Bemtér 18/C, Debrecen H-4026, Hungary c Department für Geowissenschaften, Universität München, Theresienstraße 41, D-8033 München, Germany d Faculty of Science, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic e Faculty of Science, Masaryk University, Kotlᡠrská 2, 611 37 Brno, Czech Republic f School of Geosciences, University of Edinburgh, The King‘s Buildings, West Mains Road, Edinburgh EH9 3JW, United Kingdom g Faculty of Science, Palack´ y University, 17. listopadu 12, 779 00 Olomouc, Czech Republic a r t i c l e i n f o Article history: Received 31 August 2012 Accepted 17 February 2013 Keywords: Bohemian Massif Plio-Pleistocene Basanite Melilitite K-Ar age Magmatism Sr–Nd isotopes a b s t r a c t The Plio-Pleistocene volcanic rocks of the Bohemian Massif comprise a compositional spectrum involv- ing two series: an older basanitic series (6.0–0.8 Ma) and a younger, melilititic series (1.0–0.26 Ma). The former consists of relatively undifferentiated basaltic rocks, slightly silica-undersaturated, with Mg# ran- ging from 62 to almost primitive mantle-type values of 74. The major and trace element characteristics correspond to those of primitive intra-plate alkaline volcanic rocks from a common sub-lithospheric mantle source (European Asthenospheric Reservoir – EAR) including positive Nb, and negative K and Pb anomalies. 87 Sr/ 86 Sr ratios of 0.7032–0.7034 and 143 Nd/ 144 Nd of 0.51285–0.51288 indicate a moder- ately depleted mantle source as for other mafic rocks of the central European volcanic province with signs of HIMU-like characteristics commonly attributed to recycling of subducted oceanic crust in the upper mantle during the Variscan orogeny. The melilititic series is characterized by higher degrees of silica-undersaturation, and high Mg# of 68–72 values, compatible with primitive-mantle-derived com- positions. The high OIB-like Ce/Pb (19–47) and Nb/U (32–53) ratios indicate that assimilation of crustal material was negligible. In both series, concentrations of incompatible elements are mildly elevated and 87 Sr/ 86 Sr ratios (0.7034–0.7036) and 143 Nd/ 144 Nd ratios (0.51285–0.51288) overlap. Variations in incom- patible element concentrations and isotopic compositions in the basanitic series and melilititic series can be explained by a lower degree of mantle melting for the latter with preferential melting of enriched mantle domains. The Sr and Nd isotopic compositions of both rock series are similar to those of the EAR. Minor differences in geochemical characteristics between the two series may be attributed to: (i) to dif- ferent settings with respect to crust and lithospheric mantle conditions in (a) Western Bohemia (WB) and (b) Northeastern Bohemia (NEB) and the Northern Moravia and Silesia (NMS) areas, (ii) a modally metasomatized mantle lithosphere in WB in contrast to cryptically metasomatized domains in the NEB and NMS, (iii) different degrees of partial melting with very low degrees in WB but higher degrees in NEB and NMS. The geochemical and isotopic similarity between the Plio-Pleistocene volcanic rocks and those of the late Cretaceous and Cenozoic (79–6 Ma) suggests that their magmas came from composi- tionally similar mantle sources, that underwent low degrees of melting over an interval of ∼80 Ma. The Oligocene to Miocene basanitic series that accompanied the Plio-Pleistoicene basanitic series in the NMS region indicate that they shared a common mantle source. There is no geochemical evidence for ther- mal erosion of the lithospheric mantle or significant changes in mantle compositions within the time of a weak thermal perturbation in the asthenospheric mantle. These perturbations were caused by a dispersed mantle plume or passively upwelling asthenosphere in zones of lithospheric thinning. © 2013 Elsevier GmbH. All rights reserved. ∗ Corresponding author. Tel.: +420233087240. E-mail address: ackerman@gli.cas.cz (L. Ackerman). 1. Introduction Although the Central European rift system and its associated vol- canism is well known, the underlying reasons for mantle melting and the composition and origin of source materials have remained 0009-2819/$ – see front matter © 2013 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.chemer.2013.02.001