Journal of Tectonics

Journal of Tectonics

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

Document Type : Original Article

Authors
shahriyar kershtgar 1
Mahmoudreza Heyhat 2
Sasan Bagheri 3
ebrahim gholami 4
Seyed Naser Raisossadat 4
1 Ph.D. student of tectonics, faculty of science, University Birjand, Birjand, Iran.
2 Department of Geology-Faculty of Sciences-University of Birjand_Birjand
3 geology department of sistan and baluchestan university
4 Geology department, University of Birjand, Birjand, Iran
10.22077/jt.2023.6011.1150
Abstract
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.
Keywords
Shear fracture
Strain
Conglomerate
Seh-Changi
Eastern Iran