Czech-France Joint Programme ”BARRANDE” (ministry of Education, Youth and Sports CR)

Plate-tectonic movements and paleoclimatological changes recordere in Lower Paleozoic rocks of peri-Gondwanan Europe (investigators: P. Pruner and T. Aifa, contributions: P. Štorch and J.P. Lefort, Universite de Rennes, France)

The principal aim of the Project is to elaborate a complex approach to the investigation of the Early Palaeozoic climatic changes on the territory of present Europe considering plate-tectonic movements and palaeogeographical changes. Plate-tectonic interpretation of palaeomagnetic data which indicate drift and rotations of respective terranes of peri-Gondwanan Europe will be compared with relevant palaeontological, sedimentological and, later, sequence-stratigraphical data on palaeogeographic and palaeoclimatic evolution of the territory. For this purpose, suitable rocks of the Lower Palaeozoic will be collected, preferably from the Barrandian area, central Bohemia, and these will be subjected to petromagnetic and palaeomagnetic investigations with the aim to determine palaeogeographical latitudes of the respective formations. At the same time, palaeontological and sedimentological  indicators of the climatic changes will be evaluated and the results obtained will be interpreted in a complex way both by the French and Czech research teams. Similar palaeoclimatological problems, as they exist for the Barrrandian area, have been encountered for other peri-Gondwanan terranes, e.g. for Armorica. Consequently, results of studies of palaeoclimatic changes and the methodological procedures employed during the investigations are of paramaount interest both for the French and Czech sides. We have finished laboratory procedures on the Ordovician and the Silurian rocks from the French localities of Crozon Penisculla (Formation Postolonnec), Rosan Formation,  Ploermel, Saint Malo de Phily for testing their applicability to palaeomagnetic investigations. Separation of the respective remanent magnetisation components was carried out by using the multi-component analysis of  J. L. Kirschvink. Numerous samples from the set of samples show typical three-component magnetic remanence, according to blocking temperatures.  Phase or mineralogical changes of magnetically active (mostly Fe-oxides) minerals frequently occur during the laboratory thermal tests, especially at low temperature intervals.