Analysis of extension and conjugate shear fractures in the Seh-Changi Conglomerate (The northwestern border of Sistan-Lut terrains)

The deformed Sehchangi conglomerate is exposed with an angular unconformity on the Triassic sediments on the curved northwestern border of the Sistan and Lut terrains. The Sehchangi conglomerate was undergone brittle deformation, consequently the extension and conjugate shear fractures occurred in its and no ductile deformation has been seen in matrix and pebbls of this conglomerate. According to extensional fractures, the value of strain longitudinal parameters was obtained as follows: e=0.15, S=1.15, =1.32 and =0.75. Also, the stress analysis of conjugate shear fractures in this conglomerate by the "right dihedral" and "rotational optimization" methods were calculated 1=23/190, 2=43/77, 3=38/299 and R()=0.7, R=1.23. These results indicate that the conglomerate has been experienced an elongation with some volume changes along the N70W direction. According to study of extension and conjugate shear fractures, it seems that the buckling tectonic regime in the Sechangi area which associated with the Paleogen eastern Iranian orogeny, caused the extension-shear deformations and orientation of refold structures in this area.