Neocratonic magmatic‐sedimentary basins of post‐Variscan Europe and post‐Kanimblan eastern Australia generated by right‐lateral transtension of Permo‐Carboniferous Pangaea

Abstract

AbstractThe stress from the initial coalescence of Pangaea during the mid‐Carboniferous (320 Ma) collision of Gondwanaland and Laurussia in the Variscan (Sudetic) magmatic fold belt was transmitted through Pangaea to generate the nappes and thrusts that dismembered the intracratonic Centralian Superbasin during the Alice Springs Orogeny and the megakinks that terminally deformed the Lachlan fold belt along the subducted Andean‐type margin of eastern Australia. Definitive collision was followed by a lacuna on the Pangaean platform that reflects uplift. The first release of heat at ≅ 300 Ma from the self‐induced Pangaean heat anomaly weakened the hypersensitive neocratonic crust of the inactive but still hot European and eastern Australian magmatic fold belts to become stress guides for right‐lateral transtension during anticlockwise rotation of Pangaea. Deep transtensional fractures provided a way into and through the neocratonic crust for magma ranging from S‐type granite to rhyodacitic ignimbrite to basalt, with alkaline undersaturated rocks in some rifts. Lagging behind the magma, the platform subsided at ≅290 Ma in basins by differential weakening of the crust during the release of Pangaean heat. The Gondwana facies accumulated in the Gondwanaland province and the Stephanian‐Rotliegend succession in Europe. The basins of Europe and eastern Australia continued to grow by transtension followed by mid‐Permian (270–265 Ma) thermal sagging and rifting. Their histories then diverged. Europe maintained its post‐orogenic course except in the Alpine region, where rifting and sagging continued to accommodate the western Tethys. The eastern fringe of Australia entered a new, Innamincka, orogenic cycle that developed in embryo at 265 Ma to a fully developed magmatic arc and yoked foreland basin at 258 Ma.