TS7.6 Variscan and Altai orogens in Europe and Asia and their relative contribution to the building of Pangea supecontinent |
Convener: Karel Schulmann | Co-Conveners: Jean Marc Lardeaux , José R. Martínez Catalán , Stanislaw Mazur , Min Sun , Wenjiao Xiao , Chao Yuan |
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The construction of the western part of the Pangea supercontinent was completed through recurrent amalgamation of peri-Gondwanan fragments and closure of interior oceanic basins in the Devonian-Carboniferous. This Wilson type process formed the linear Variscan orogen in Europe and North America typified by 400-370 Ma (U)HP metamorphism related to oceanic and continental subduction that was followed by 350-340 syncollisional (HP) granulite facies metamorphism and extensive magmatic recycling of continental crust. On the other hand, eastern Pangea was simultaneously constructed by accretion of the peri-Pacific oceanic crust and continental ribbons along the Siberian Craton. The main contractional 400 – 350 Ma Altai cycle was associated with crustal thickening of juvenile oceanic complexes, their melting and exhumation of deep granulitic crust. Both the Variscan and Altai orogenic cycles contributed to a spectacular and uprecedented growth of Pangea supecontinent and their apparent synchroneity calls for correlation of Paleozoic processes on a global scale. These correlations need to compare geophysical signature, sequence of contractional and extensional events as well as metamorphic and magmatic processes that operated simultaneously in the interior of the „Pangean“ plate assemblage and along its boundary with the Paleopacific plate. A new image emerges allowing understanding of plate movements, subduction processes and causal relationship between the orogens and formation of the last supercontinent in Paleozoic times.