Conference proceeding
Intraplate volcanism in Western Bohemian Massif; isotopic characteristics
International Geological Congress, Abstracts = Congres Geologique International, Resumes, Vol.33
33rd international geological congress
2008
Abstract
We present preliminary results of isotopic composition of Cenozoic volcanic rocks from western part of Bohemian Massif. The Bohemian Massif is the largest surface exposure of basement rocks in central Europe. In Cenozoic times the widespread rifting and alkaline volcanism occurred within the Bohemian Massif in relation to the Atlantic Ocean opening and Alpine orogeny. In the Bohemian Massif, which formed the northern foreland of the Alpine orogen, the Variscan shear zones were reactivated during Cenozoic extension and provided channels for alkaline magmas. Volcanic activity occurred in a wide time span, from 0.26 to 79 Ma, with the main phase of syn-rift volcanism in the eeske stoedohooi from Late Eocene to Middle Miocene (42-18 Ma) which produced the basanite-phonolite series (Ulrych & Pivec 1997, Ulrych et al., 2008). Studied volcanic rocks are c. 12 Ma old and according to TAS classification belong to the alkaline volcanic series. They represent basanites, basaltic trachyandesites, trachybasalts and trachytes with wide range of SiO (sub 2) (41 - 67 wt %) and MgO (0.1 - 14.6 wt %) contents. Higher SiO (sub 2) and lower MgO abundances are attributed to advanced fractional crystallization and crustal contamination processes. The double-spike Pb data reveal values from 18.86 to 20.04 for (super 206) Pb/ (super 204) Pb, 15.63 to 15.66 for (super 207) Pb/ (super 204) Pb and 38.93 to 39.68 for (super 208) Pb/ (super 204) Pb. Basanite from Krasny Les has the highest values of Pb isotopic ratios and the lowest Sr isotopic ratios ( (super 87) Sr/ (super 86) Sr=0.7033). Pb isotopic ratios are typical of OIB volcanism and show values similar to German part of CEVP but lower than easternmost part of CEVP (SW Poland). High (super 207) Pb/ (super 204) Pb ratios diverge into the direction of EMII mantle source. Higher Sr isotopic ratios and known from literature lower (super 143) Nd/ (super 144) Nd (Ulrych et al. 2002) also indicate the influence of EM component in the mantle source of Bohemian volcanics and modification of magma composition by crustal contamination and assimilation processes.
Details
- Title: Subtitle
- Intraplate volcanism in Western Bohemian Massif; isotopic characteristics
- Creators
- Anna Ladenberger - Uppsala UniversityDavid W Peate - University of IowaCestmir Tomek - University of SalzburgMarek Michalik - Jagiellonian University
- Resource Type
- Conference proceeding
- Publication Details
- International Geological Congress, Abstracts = Congres Geologique International, Resumes, Vol.33
- Conference
- 33rd international geological congress
- Publisher
- International Geological Congress
- Alternative title
- 33rd international geological congress; abstracts
- Language
- English
- Date published
- 2008
- Academic Unit
- Earth and Environmental Sciences; Honors Program
- Record Identifier
- 9984240807002771
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