A Discussion on global tectonics in Proterozoic times - Vertical movements in Proterozoic structural provinces

Abstract

The extent, consistency and timing of vertical movements both in cratonic and in mobile segments of the continental crust are discussed with particular reference to movements taking place during Proterozoic times. The distribution of unconformities and erosion-surfaces, and the variations in cover-successions, in metamorphism, in style of igneous activity and in the closing of isotopic systems are considered in this context. Many of the most ancient cratonic masses appear to have undergone only very small vertical movements over periods up to 2000 Ma in length. Erosion of the basement of many cratonic regions seems to have been concentrated in periods of only a few hundred million years and was not renewed by persistent later uplift. The responses of these cratonic regions were influenced by the distribution of Archaean massifs in them. The history of uplift in certain Proterozoic mobile provinces is seen to have a bearing on the problem of the origin of these provinces.