D. Brown et P. Spadea, Processes of forearc and accretionary complex formation during arc-continent collision in the southern Ural Mountains, GEOLOGY, 27(7), 1999, pp. 649-652
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.