Timing of the Avalonia–Baltica plate convergence as inferred from palaeogeographic and stratigraphic data of chitinozoan assemblages in west Pomerania, northern Poland
Published:January 01, 2002
Joakim Samuelsson, Marco Vecoli, Wiesław S. Bednarczyk, Jacques Verniers, 2002. "Timing of the Avalonia–Baltica plate convergence as inferred from palaeogeographic and stratigraphic data of chitinozoan assemblages in west Pomerania, northern Poland", Palaeozoic Amalgamation of Central Europe, J. A. Winchester, T. C. Pharaoh, J. Verniers
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Tectonically disturbed Ordovician rocks penetrated by deep drillholes in Pomerania, NW Poland (Koszalin-Chojnice Zone) belong to the Heligoland-Pomerania Deformation Belt. Earlier data demonstrate that the Avalonia-Baltica collision occurred in Late Ordovician times, but in Pomerania, the timing of convergence has not been ascertained, and it is uncertain if the rocks underneath the Koszalin-Chojnice Zone belong to Avalonia or Baltica. Data from chitinozoans, organic-walled Palaeozoic microfossils with applications in biostratigraphy and palaeobiogeography, were assessed from ten boreholes (Brda 2; Brda 3; Chojnice 5; Karsina 1; Kościernica 1; Nowa Wieś 1; Okunino 1; Sarbinowo 1; Skibno 1; Wyszebórz 1) to address these problems. The results improve the biostratigraphy of the cores and demonstrate that the youngest Ordovician rocks are of a Burrellian (early mid Caradoc) to Cheneyan (late mid Caradoc) age. Because these rocks are interpreted as forming part of the deformation belt, the obtained ages put a lower age limit on the initiation of foreland basin sedimentation on the foreland of the orogeny, i.e. the Baltic platform. Quantitative comparison of chitinozoan assemblages demonstrates a high level of similarity between Pomerania and Avalonia. Together, Pomerania and Avalonia show greater similarity to Baltoscandia than to North Gondwana, supporting the idea that the Tornquist Ocean had narrowed significantly in early Caradoc times.
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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.