Collision and Postcollision Structural Evolution of the Andrianovka Suture, Sredinny Range, Kamchatka

Abstract

The structural evolution of the Andrianovka Suture exposed on the eastern slope of the Sredinny Range in Kamchatka is considered. The main structural suture divides the metapelitic rocks of the Kamchatka Group and the metavolcanics of the Andrianovka Formation. The early collisional deformational event related to the westward overthrusting of marginal-sea and island-arc complexes is established in the structural evolu- tion of the allochthonous complex (Andrianovka and Irunei formations). The normal faulting at the postcolli- sion stage is displayed in the structural assemblages of the autochthonous and allochthonous complexes. A zone of normal ductile fault in the upper portion of the autochthon (Kamchatka Group) is described. It is suggested that the exhumation of high-grade metamorphic rocks may correspond to the evolutionary scenario of the Cor- dilleran-type metamorphic core formation.