Processes of forearc and accretionary complex formation during arc-continent collision in the southern Ural Mountains

The southern Ural Mountains of Russia contain a well-preserved, well-expose d Paleozoic accretionary wedge and forearc that can be readily compared to those in active are-continent collision zones. The early convergent history in the southern Ural Mountains is marked by the generation of boninite-bea ring are tholeiites in the Magnitogorsk forearc, followed by are tholeiite to calc-alkaline volcanism, With the entry of the East European craton cont inental crust in the subduction zone, volcanism waned and stopped, and high -pressure metamorphism of its leading edge took place. The arrival of the f ull thickness of the continental crust at the subduction zone is marked by increased sedimentation in the forearc basin and deposition of are-derived volcaniclastic turbidites across the subducting slab. These, together with offscraped continental material, the exhumed high-pressure rocks, and a Ihe rzolite massif, formed an accretionary wedge. A broad melange zone containi ng ultramafic fragments separates the forearc basement from the accretionar y wedge, and marks the damage zone that developed along the backstop region . shallow-water carbonates deposited unconformably on top of the mildly def ormed are record the end of the collision and the collapse of the arc.