Proterozoic Geology: Selected Papers from an International Proterozoic Symposium
A tectonic review of the Proterozoic
Published:January 01, 1983
Brian F. Windley, 1983. "A tectonic review of the Proterozoic", Proterozoic Geology: Selected Papers from an International Proterozoic Symposium, L. G. Medaris, Jr., C. W. Byers, D. M. Mickelson, W. C. Shanks
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The fact that lithospheric plates were beginning to respond (2.5 b.y. B.P.) to deformation, intrusion, and deposition in a mode comparable to that of today is indicated by the development of linear/arcuate orogenic belts bordering continental plates, leaving stable interiors with little-deformed cratonic sequences and linear dike swarms, the development of aulacogens and continental-rise sequences, island arcs, Andean arcs and back-arc basins, back-arc thrust belts adjacent to high-potash minimum-melting granites and slip-line indentation fracture systems bordering linear/arcuate orogenic belts, and geochemical patterns of igneous rocks comparable to modern tectonic equivalents; all these features indicate that modern-style plate tectonics began in the early Proterozoic.
Archean-type greenstone belts and granulite-gneiss belts continued to form throughout the Proterozoic, probably in marginal basins and the deeper levels of Andean belts, respectively. In the early Proterozoic a large number of orogenic belts formed, which are increasingly being interpreted in terms of Wilson Cycle processes. In the mid-Proterozoic (1.7 to 1.2 b.y. B.P.), major abortive rifting gave rise to anorogenic sodic anorthosites and rapakivi granites. In the period 1.0 ± 0.2 b.y. B.P., the Grenville and Dalslandian belts in the North Atlantic region formed with prominent Andean-type and Himalayan-type stages of development; today we see deeply eroded levels of these belts. The 0.8 to 0.57 b.y. B.P. Pan-African/Braziliano/Cadomian belts are widely acclaimed as having formed by Wilson Cycle tectonics.
The Proterozoic was a period of substantial lateral plate motion, accretion, and subduction and of corresponding crustal growth, although less intense than in the Archean. It was also a period of differentiation of the continental crust and the formation of potash granites in upper levels.