The study of mylonitic granodiorites in the lakhshak grnitoides pluton, Nw of Zahedan, Iran

Category Petrology
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

      The lakhshak intrusive body, located in the Northwest of the Zahedan, is a part of Zahedan-Saravan plutonic belt. This Oligo-Miocene intrusion, as an elongated pluton, intruded Eocene fylish type meta-sediments that belong to the Sistan suture zone between Lut and Afghan blocks.
   The intrusive body composed of holocrystalline acidic rocks, ranging in composition from biotite granodiorite to rarely hornblende granodiorite with predominant quartz, plagioclase, K-feldspar, biotite and variable amount of hornblende and opaque.
   Within several narrow to extensive shear zone (0.5 to 100 meter wide) with the NE direction in the intrusion and NW direction in the contact, the granodiorite and their host rock undergo ductile deformation. The typical appearance of the deformed granodiorite in the shear zones is that of a protomylonite to mylonites with ?augen? shaped feldspar porphyroclasts. However, due to heterogeneous deformation, some sheared granodiorites are only weakly deformed. Occurrence of high temperature unaffected magmatic paragenesis of granodiorite inside the mylonitic granodiorite, could demonstrate a sub-solidus high temperature ductile deformation. In the other word, it seems that both magmatism and mylonitization was active contemporary.