Showing 3 results for Zagros
Bahman Rahimzadeh, Jamshid Hasanzadeh, Fariborz Masoudi,
Volume 13, Issue 4 (2-2014)
Abstract
Gabbroic stocks and dykes associated with Ophiolitic Basalts and peridotites are outcropped in the Sawlava town area. Sawlava ophiolite is part of Kurdistan Ophiolitic complex that located in sheared zone between high Zagros and northern Sanandaj-sirjan Zone. This study focused geochemistry and dating of granular and pegmatoid gabbros that due to closing to main recent fault (MRF) some part of them found milonitic fabric. Gabbros have 47.84 to 51.65 percent SiO2 and almost formed from tholeiitic magma. Labradorite plagioclase and diopside and augite clinopyroxens with Mg# of 83.90 to 88.90 respectivly are main minerals of gabbros. Based on geochemical and geotectonic diagrams, gabbros generated from slightly deplete magma which formed in back arc supra-subduction zone. U-Pb dating of zircons presents an average age of 38.3±1.3 Ma for gabbros. Late Eocene age from Sawlava gabbros and similar gabbros bodies related to ophiolites along Zagros suture, could indicate that neo-tethyan ocean closed after Eocene in the Kurdistan region.
Reza Alipoor, Seyed Ahmed Alavi, , , ,
Volume 16, Issue 41 (5-2015)
Abstract
In this research, changes in structural geometry of thrusting of the Aghajari anticline on the Marun anticline in Dezful Embayment (SW Iran) have been studied based on seismic reflection data. These two anticlines have a NW –SE trends and thrusting of the Aghajari anticline on the Marun anticline is located in North of the study area. The Marun anticline with visible plunge is forming in the south of study area and 4 and 5 seismic profiles, and most of deformation is concentrated in Aghajari anticline. Also, Marun anticline has formed in the middle of the study area, but thrusts not formed in this part of anticline and maximum thrusting of Aghajari anticline on the Marun anticline is visible. There is a shallow thrust in south limb of two anticlines in northern part and an upper thrust from Gachsaran formation exposed from progressive deformation and finally a shallow thrust propagate to surface in both anticlines in the end of NW parts of study area and back thrusts separate from main shallow thrust in two anticlines. But unlike the Aghajari anticline, an upper thrust from Gachsaran formation propagates to surface with progressive deformation in the Marun anticline showing low depth of the Marun anticline.
F Noori Sandbani, H Azizi,
Volume 16, Issue 42 (5-2015)
Abstract
Gabbroic bodies with NW-SE trend outcropped in the southwest of Sahneh in the north of Gamassiab River, W. Iran are part of Zagros ophiolite . This complex is separated from the other geological units by deep faults and cut by pyroxenitic dikes. The field evidences, petrographic, geochemical and mineral paragenesis of these rocks are completely different from the fresh and un-altered gabbroic rocks. Furthermore the high ratios of 143Nd/144Nd (0.512945-0.513021) and low ratios of 87Sr/86Sr (0.70334-0.70656) indicate the sub-oceanic depleted mantle source for the origin of these rocks. Low variation of 143Nd/144Nd ratios, increasing of 87Sr/86Sr ratios, decreasing of SiO2 and increasing of CaO and Al2O3 mainly concludes the high reaction of gabbroic rocks with seawater. The pargenetic assemblages of altered gabbros are grossular/hydrogrossular, anderadite, epidote, idocrase (vesuvianite) and diopside. The mineral paragenesis reveals that the rodingitization was occurred by reaction of gabbroic bodies with high alkali water at a shallow depth
