Main Uralian Fault

Formation

The Main Uralian Fault formed in the Riphean (early Neoproterozoic) in the breakup of the supercontinent Rodinia as a rift valley between the Baltica and the Angara Plate (Siberian craton). As these two plates pulled apart eventually a mid-ocean ridge formed. The ridge was of basic (basalt) and ultramafic material. Some 500 million years later, in the Silurian, a subduction zone formed on the western margin of the Angara Plate, which at the time was on the western edge of Gondwana, and the oceanic plate was subducted underneath the Angara Plate, accreting some of the basalts and ultramafics onto the Angara Plate. Sialic sediments were metamorphosed, melted and intruded into the rocks above as granites. By the early Carboniferous the oceanic plates were completed subducted and the eastern margin of Baltica, then on the eastern edge of Laurussia began to collide with the western edge of Angara. In the south the western edge of Kazakhstania may have been pushed under Baltica. This collision in known generally as the Variscan orogeny, and specifically as to the Urals as the Uralian orogeny The collision lasted nearly 90 million years from the Carboniferous to the early Triassic. The MUF remained active as the plates ground against each other as Pangea was formed and the Ural Mountains were raised up.