Did a change in tectonic regime occur between the Phanerozoic and earlier Epochs?

A compilation of palaeogeographical maps of the Neo Proterozoic (Ptz) and Phanerozoic (Pz) 0.6 Ga BP to the present is analyzed in the terms of the (a) ratio between continental to oceanic crust areas (in short continent- to-ocean ratio), (b) length of spreading centres and (c) length of subduction zones. The variation of these tectonic processes is then compared to the variations occurred during the Archean (Arc 3.8-2.5 Ga BP) and Proterozoic (Ptz 2.5-0.54 Ga BP). The discussion takes the geomagnetic field and changes in length of the day (LOD) into account as well. From the constancy of the continentto- ocean ratio through Pz and from the small size of the continental area above sea level in Neoproterozoic it follows that at the border between Ptz and Pz there has been a large change of the length of the shelf zones. This change can explain contemporary change of the despinning rate from about 0.35 to about 1.79 ms/century. In general, our findings suggest a change in tectonic regime at the border between Ptz and Pz. © Springer-Verlag 2012.