Movements of the Continental Crust and Lithosphere-Aesthenosphere Systems in Precambrian Times

Abstract

Since publication of the first volume of Tidal Friction and the Earth’s Rotation, considerable advances have been made in our understanding of the behaviour and relative movements of the Earth’s surface lithosphere in Precambrian times. In particular, an improved understanding of the temperature-pressure phase relationships of crustal and upper mantle materials has refined the models of lithosphere-aesthenosphere interactions during earlier phases of the Earth’s history (see for example Baer 1977 and Tarling 1980), and a widening of the palaeomagnetic data base has confirmed that these interactions have been radically different during the two major divisions of post-Archaean (<2700 m.y.) times. The present-day scheme of “plate tectonics” incorporating six large rigid plates and a number of smaller plates growing at constructive margins along the mid-ocean ridges, moving relative to one another along transform faults (conservative margins), and being consumed at destructive margins is seen to be only one stage in an evolving system of surface tectonics. It should more specifically be described as “multi-continent” plate tectonics with the Proterozoic (2700-570 m.y.) regime distinguished as “single-continent” plate tectonics.