Document Type : Original Article
Authors
Department of Earth Sciences, Faculty of Natural Sciences, Tabriz University, Tabriz, Iran
Abstract
The Tazekand mineral prospect, as a part of Tarom-Hashtjin metallogenic belt, is located ~45 km northeast of Zanjan City, NW Iran. Based on field, petrographic and geochemistry investigations, the lithological composition of the intrusive rocks in the area varies from monzonite, diorite, granodiorite to gabbro and the volcanic units range of trachy andesite, andesite to basaltic andesite. These rocks with per-aluminous to meta-aluminous nature, are related to High-K calc-alkaline to shoshonitic magmatic series, and belong to I-type granites. Based on the diagrams illustrating the tectonic setting, these rocks formed in a post-collision volcanic arc environment on an active continental margin. In the Harker diagrams, SiO2 has negative correlation with Al2O3, MgO, MnO, CaO, Fe2O3, P < sub>2O5, TiO2, Co, V, Sr, Ni and Cr and positive correlation with K2O, Na2O, Zr and Rb. Enrichment of LILE (Cs, Ba, Rb, Th, U and Pb) and LREE and depletion of elements with high field strength (Ti, Y, Zr, Nb and Dy) and HREE are other geochemical features in the Tazekand intrusive rocks. On the basis of geochemical data, both mantle and crust components have been effective in the formation of magma for the studied intrusive rocks. The magma producing of these rocks is formed by the mixing of basaltic melts derived from the mantle and the melt resulting from the partial melting of the lower crust in balance with pyroxene and amphibole residues at a depth of less than 40 km.
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