Implications of strain and vorticity of flow analyses to interpret the kinematics of an oblique convergence event (Zagros Mountains, Iran)

Abstract

Finite strain and vorticity of flow analyses were carried out within the Deh Vazir deformed conglomerates in the Sanandaj-Sirjan metamorphic belt (Zagros Mountains, Iran). This belt is in a sequence of tectono-metamorphic complexes made of low- to high-grade metamorphic rocks affected by a polyphase deformation history. Using R f/φ technique for two-dimensional strain analysis showed that the finite strain of XZ plane is R S = 3.7 ± 0.70. The calculation of the harmonic mean from the axial ratios of the extracted pebbles and plotting these data in the Flinn diagram resulted in K = 0.7 ± 0.38 (i.e. oblate strain ellipsoid). Kinematic vorticity analysis of deformed pebbles showed that W K parameter is 0.59 ± 0.10 (i.e. pure-shear dominated non-coaxial flow). The results quantitatively support the recognition of a partitioned dextral inclined transpressive regime with bulk triclinic symmetry along the Sanandaj-Sirjan metamorphic belt resulted from the oblique collision between the African–Arabian continent and the Iranian microcontinents.