Plate tectonics and geosynclines

Abstract

Kay's (1951) classification of geosynclines, involving bulk sedimentary, volcanic and tectonic assemblages, is accommodated within the megaframework of oceanic expansion and contraction by lithospheric accretion and consumption. Apparently, entirely continental eugeosynclines do not exist; geosynclines occur in oceans with marginal continental shelves, continental rise, deep ocean basins, small ocean basins and island arcs. An orogen, resulting from crustal loss in trenches at Benioff zones, grows progressively away from the trench, either on the continental margin or as an island arc. The term, kinegeosyncline, is proposed for the contracting trough, trapped between continental margins and growing orogens. The arrival of a continental mass, with its continental margin sediments, at a trench results in collision and an orogen, which may suture continents together.