Geology and geodynamic evolution of the high-P/low-T Maksyutov Complex, southern Urals, Russia

The high-pressure/low-temperature Maksyutov Complex is situated in the sout hern Urals between the Silurian/Devonian Magnitogorsk island are and the Ea st European Platform. The elongated N-S-trending complex is made up of two contrasting tectono-metamorphic units. Unit 1 consists of a thick pile of P roterozoic elastic sediments suggested to represent the passive margin of t he East European Platform. The overlying unit 2, composed of Paleozoic sedi ments, volcanic rocks, and a serpentinite melange with rodingites, is inter preted as a remnant of the Uralian Paleo-ocean. Devonian eastward subductio n of oceanic crust beneath the Magnitogorsk island are resulted in an incip ient blueschist-facies metamorphism of unit 2 indicated by lawsonite pseudo morphs in the rodingites. While unit 2 was accreted to the upper plate, sub duction of the continental passive margin caused the high-pressure metamorp hism of unit 1. Buoyancy-driven exhumation of unit 1 into the forearc regio n led to its juxtaposition with unit 2 along a retrograde top-to-the-ENE sh ear zone. Further exhumation of the Maksyutov Complex into its present tect onic position was accomplished by later shear zones that were active as nor mal faults and are exposed along the margins of the complex. At the western margin a top-to-the-west shear zone juxtaposed a low-grade remnant of a Pa leozoic accretionary prism (Suvanyak Complex) above the Maksyutov Complex. Along the eastern margin a top-to-the-east shear zone and the brittle Main Uralian Normal Fault emplaced the Maksyutov Complex against the Magnitogors k island are in the hanging wall.