Folded layering in the Deh Vazir ductile shear zone, Iran. This is a structure as described by vanderPluijm and Marshak (1997); folding accompanies shearing and occurs where a sequence of interlayered weak and strong rock layers is caught between the opposing boundaries of a shear zone. In such circumstances, displacement of the rigid shear zone boundaries with respect to each other causes the intervening rock to fold. The Deh Vazir shear zone mainly consists of foliated and lineated marble and greenschist. Metamorphic grade is generally low grade (Sarkarinejad et al., 2010). The photograph shows how strong marble layers act as a shear zone boundary and weak greenschist layers between the marble layers have been subject of shearing. Location: Deh Vazir shear zone in the Southwest of the HP-LT Sanandaj-Sirjan metamorphic belt, Iran. PhotoID190
Sarkarinejad, K., Samani, B., Faghih, A., Grasemann, B., Moradipoor, M., 2010. Implications of strain and vorticity of flow analyses to interpret the kinematics of an oblique convergence event (Zagros Mountains, Iran). Journal of Asian Earth Sciences 38, 34-43
van der Pluijm, B.A., Marshak, S., 1997. Earth Structure: an Introduction to Structural Geology and Tectonics, McGraw-Hill, New York.
This is a photograph of the month in the Journal of Structural Geology