Palaeozoic terrane amalgamation in Central Europe: a REE and Sm–Nd isotope study of the pre-Variscan basement, NE Bohemian Massif
Published:January 01, 2002
Quentin G. Crowley, Hilke Timmermann, Stephen R. Noble, J. Grenville Holland, 2002. "Palaeozoic terrane amalgamation in Central Europe: a REE and Sm–Nd isotope study of the pre-Variscan basement, NE Bohemian Massif", Palaeozoic Amalgamation of Central Europe, J. A. Winchester, T. C. Pharaoh, J. Verniers
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The West Sudetes, NE Bohemian Massif, comprises several suspect terranes accreted to the margins of Laurussia during Variscan orogenesis. Whole rock REE and Sm-Nd isotope data for seven separate provinces (Izera, Kaczawa, Rudawy Janowickie and Kłodzko complexes; Fore-Sudetic and Góry Sowie Blocks; Slęża Ophiolite) suggest involvement of a variety of crustal and mantle sources. Felsic metasedimentary rocks (εNd(t) = −8.3 to −5.0) have two stage TDM ages of 1.9 to 1.5 Ga, whereas acidic metavolcanic rocks and granite gneisses (εNd(t) = −5.4 to +0.8) have two stage TDM ages of 1.5 to 1.0 Ga. A range of sources is implicated: predominantly Archaean and Palaeoproterozoic sources for the metasedimentary rocks, and Archaean. Palaeoproterozoic and Neoproterozoic to early Palaeozoic sources for the meta-igneous felsic lithologies. LREE depleted tholeiitic metabasites ((Ce/Yb)N = 0.8 to 3.4) generally have εNd(t) = +4.0 to +9.1, indicating derivation from depleted mantle asthenosphere. LREE enriched meta-alkali basalts ((Ce/Yb)N = 4.6 to 10.1) with εNd(t) between +3.1 and +7.0 implicate utilization of enriched mantle asthenosphere.
Analogous lithologies from elsewhere in the Sudetes, North Bohemian Massif and the Armorican Terrane Assemblage have similar REE abundances, εNd values and TDM ages. Complexes previously considered to have had disparate Neoproterozoic to early Palaeozoic histories may be integrated into a unifying geodynamic model of derivation from the North Gondwanan (North African) margin during a widespread episode of continental margin break-up.
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Palaeozoic Amalgamation of Central Europe
Palaeozoic Amalgamation of Central Europe summarizes recent research designed to clarify the timing, geometry and processes by which discrete terranes of Central Europe became amalgamated during the Palaeozoic Era. The area studied extends from the southern North Sea to Central Poland along the Trans-European Suture Zone, covering much of Germany, Denmark, Belgium, the Czech Republic and Poland.
The 16 papers within the volume are divided into five sections: biostratigraphic/provenance evidence; isotopic constraints; petrological and geochemical evidence; structural evolution; seismic traverses and deep crustal structure. The first section contains papers summarizing continent-specific micropalaeontological and sediment provenance information backing current debates about microcontinent derivation and timing of their accretions to the proto-European continent, Baltica. The section on isotopic constraints discusses the use of isotopic dating to constrain the timing of accretions of rock units exposed in the northern Bohemian Massif, while the following section has more detailed studies of metamorphosed ophiolitic complexes adjoining palaeosutures in the same area. The two papers on the structural evolution of the area contrast a detailed review of the structural evolution of the Sudetes, with a broader, more regionally based hypothesis for the structural evolution of all Central Europe. The final section discusses models based on extensive seismic traverses in contrasting parts of the area - Belgium, the southern North Sea and Poland. This wide-ranging study thus encapsulates the most up-to-date ideas on the Palaeozoic amalgamation of Central Europe from the leading international researchers in the field.
The volume will be of interest to those earth scientists in industry and academia with a broad-based interest in the construction of the European continent, primarily biostratigraphers, geophysicists, structural geologists and geochemists.