QE551 : The genetic relation of adakites and hydrothermal mineralization in the Joghatay region, northwest Sabzevar
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2023
Authors:
Ebrahim Dastourani [Author], [Supervisor], Habibolah Ghasemi[Supervisor]
Abstarct: Joghatay-Sabzevar region is located on the northern margin of the central Iran zone in the Sabzevar subzone. Subduction of the Neo-Tethys oceanic crust of Sabzevar under the eastern Alborz zone caused the replacement of the Sabzevar ophiolitic complex during the Upper Cretaceous-Paleocene and the formation of the Quchan-Sabzevar magmatic belt. The Eocene volcanic rocks are composed of andesite, trachyandesite, dacite, trachydacite and rhyolite lava flows and tuffs. Subvolcanic and intrusive rocks with composition of trachyandesite, quartz monzodiorite, monzodiorite, diorite, and monzogabbro, in the forms of stock, dome and dyke have been injected into the Upper Cretaceous ophiolitic complex and the Eocene volcanic-sedimentary sequences. The primitive mantle-normalized element patterns in the subvolcanic and intrusive rocks shows that positive anomaly of K, Sr, Rb and Ba, relative enrichment of LREE compared to HREE, depletion of Y and HFSE and absence of Eu anomaly and negative anomaly of Ti and Nb, which is the geochemical features of igneous rocks in subduction zones. The major and trace elements geochemical data show that the partial melting of the subducted oceanic crust in the eclogite to amphibolite facies have played a role in the formation of Cenozoic igneous rocks in the region. The volcanic-intrusive rock samples of this region are located in the continental margin volcanic arc field in some geochemical diagram, while these sample are placed in the slab failure area in the other diagrams. Volcanic and intrusive rock samples are located in high-silica adakites area and far from dominant of the normal volcanic arcs. Alterations in this region include serpentinization of peridotites and dunites, rodengitization of gabbros, and propylitic, phyllic, argillic, silicic, and carbonate alterations in Cenozoic volcanic and intrusive rocks, which phyllic and to some extent argillic alterations are associated with gold (copper) mineralization. Quartz monzodiorite to diorite bodies with the nature of high-silica adakites in this region (e.g., Jalamabadan area) are potential targets for gold (copper) mineralization, which after the melting of the subducted oceanic slab emplaced in the thickened crust area during the syn- to post-collisional environment and likely have a Post-Eocene age. Gold content in two selected samples from the Jalamabadan area is 443 and 1288 ppb and Cu grade is less than 500 ppm, which indicating to gold (copper) mineralization in this area.
Keywords:
#Petrology #geochemistry #alteration #Au (Cu) mineralization #high-silica adakite #Joghatay- Sabzevar region. Keeping place: Central Library of Shahrood University
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