Document Type : Original Article
Authors
Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
Abstract
The Pardad copper deposit lies in the Tertiary volcanic-sedimentary zone of the Abbas Abad-Kahak, south of the Sabzevar ophiolitic belt on the northeastern margin of the Central Iran. It comprises of a widespread Eocene andesite, basalt, rhyolitic tuffs and agglomerate volcanic rocks affected by the intrusion and semi-intrusive bodies (e.g., tonalitic to monzonitic quartz), which altered them to propylitic, sericitic and hematitic alteration zones. The mass balance findings indicate an enrichment of Fe2O3, MgO, CaO and copper, in the propylitic alteration samples which is in agreement with the presence of copper sulfides along with calcite and epidote. In the sericitic zone, the amount of CaO, K2O, Na2O, MgO, MnO, P < sub>2O5 and elements of Ba, Sr, Rb, Hf, Ta, W, Cr have decreased, which is the result of chloritization of ferromagnesian minerals and destruction of feldspar. Depletion of HREEs in the propylitic alteration zone can be due to chloride complexes and partial enrichment of LREEs due to surface absorption by minerals such as chlorite, epidote and iron oxides. Meanwhile, the enrichment of LREEs in the sericitic alteration zone is linked to the stabilization of these elements in primary minerals like apatite, sphene, and zircon. The hematite zone exhibits elevated levels of Co, Ni, Cr, V, Ag, and As elements, a phenomenon attributed to the surface absorption of metals on iron oxide mineral surfaces.
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