1- Bu-Ali Sina University
2- Bu-Ali Sina University , l.izadi@basu.ac.ir
Abstract: (68 Views)
The Alvand intrusive pluton, located in Hamadan Province within the Sanandaj–Sirjan zone, exhibits a well‑developed shear zone along its northern margin, southeast of Heidareh Qazi‑khan village, at the contact between the intrusion and the host rocks. The studied shear zone is parallel to the intrusive contact, trending north–south and dipping steeply to nearly vertical. In this area, the transition between the metamorphic host rocks and the intrusive body is gradual, and granite layers have been injected into the schists as dikes of variable thickness. These vertical dikes are completely deformed and mylonitic, and even the host rocks display deformation features. Kinematic indicators reveal a dominant reverse movement with a minor dextral (right‑lateral) strike‑slip component within the shear zone. To evaluate the nature of deformation, samples of mylonitic granites were collected perpendicular to the shear zone and to the intrusion–host contact. The magnitude of shear strain and consequently the proportion of simple‑shear and pure‑shear components were determined using two techniques based on porphyroclast geometry: the Porphyroclast Aspect Ratio method and the Rigid Grain Net method. Kinematic and shear‑strain analysis indicates that the Wk values range from 0.56 to 0.77, suggesting that the studied shear zone represents a general shear zone, involving a combination of simple and pure shear components.
Type of Study:
Original Research |
Subject:
Tectonics Received: 2025/12/10 | Accepted: 2026/04/27