ROLE OF STRIKE-SLIP FAULTS IN LATE PALEOZOIC-EARLY MESOZOIC TECTONICS AND GEODYNAMICS OF THE ALTAI-SAYAN AND EAST KAZAKHSTAN FOLDED ZONE

Abstract

Correlation and synthesis of published and new structural, paleomagnetic, geochronological, and paleogeographic data from the Altai-Sayan and East Kazakhstan orogenic areas in Central Asia show an important role of strike-slip faulting in their evolution. The pattern of major strike-slip faults outlines a terrane collage produced by a Late Devonian-Early Carboniferous collision of Gondwanian terranes (Altai-Mongolia and others) with Siberia and a Late Carboniferous-Permian collision of East Europe, Kazakhstan, and Siberia. The accreted continental margins were cut by strike-slip faults and conjugate thrusts into numerous terranes, which mixed with one another and disturbed the previous structural and facies framework. The first collision stage was accompanied by the formation of the Charysh-Terekta system of right-lateral transforms, followed by left-lateral strike-slip faulting in the Kurai and Kuznetsk-Teletsk-Bashkaus zones. The Siberia/Kazakhstan collision involved left-lateral motion along the Chara ophiolite belt and the Irtysh and North East shear zones. Deformations associated with each collision stage are progressively younger toward the center of Siberia; the amount of horizontal displacement decreases in the same direction from a few thousands to hundreds of kilometers.