Palaeomagnetism and plate tectonics since the lower palaeozoic

Abstract

The pattern of palaeomagnetic curves, describing the pole “motions” for the individual continental blocks, was investigated using world-wide palaeomagnetic data with particular regard to the epochs of the Cambrian and the Ordovician. Czechoslovakian data were used to judge the suitability of the pole positions which could be considered either as north or south, and to revise the curves by a suitable choice of polarity, so that they could be used to deduce unique trajectories of continental wandering, as well as their configuration in a single ancient continent, the Pangaea, in the Cambrian. Moreover, the system of curves may also be used to determine directly the distribution of the continents in the individual geological epochs. It was found that the continental drift was markedly affected by the Coriolis force. Mainly rotational motions of the continental blocks were observed round a point centre of rotation, clockwise in the Northern Hemisphere. An explanation of the development of the world-wide system of continental blocks from the Cambrian to the present is proposed. The results indicate that the geographic poles have not changed their positions considerably and that the geomagnetic field always had a dipole character. The investigated distribution of the continental blocks for the individual geological epochs agrees with the palaeolontological and geological facts pertaining to changes of climate, as determined for the individual continents. An important result is the determination of the “pilot-pole” centre (approximately 30° N, 30° E) around which rotational and translational motions of the continental blocks took place and which enable one to determine the positions of the continents in the geological past in terms of the present geographic network.