Principal mechanisms of peripheral continental growth during supercontinent cycle
The growth of eastern Pangea involves three contrasting orogenic cycles: 1) Baikalian cycle (570-540 Ma) consists of accretion of peri-Rodinian continental, Mirovoi and Panthalassan oceanic fragments to the Siberian margin followed by extensional HT reworking, the growth of magmatic arc, giant accretionary wedge and intraoceanic basin. 2) Altai cycle is typified by crustal thickening followed by syn-extensional melting of the accretionary wedge (420-380 Ma) and the opening of Mongol-Okhotsk ocean. Cycle terminates by the growth of migmatites domes (370-340 Ma), thrusting of intraoceanic ophiolites and relamination of molten material beneath oceanic crust. 3) Paleotethysian cycle (300-220 Ma) is represented by oroclinal buckling of the hybrid oceanic lithosphere. The Baikalian cycle is related to advances and retreats of Panthalassa ocean. Altai cycle results from dynamically advancing and retreating subduction of young and hot Rheic type ocean beneath Pacific one. This hot, weak and hybrid lithospheric segment was shortened and incorporated into Pangea supercontinent.