H. A. Tajeddin; E. Rastad; A. Yagoubpour; M. Mohajjel
Abstract
Barika deposit is the first and only recognized gold (and silver) rich – massive sulfide deposit in Iran which is located at 18 km east of Sardasht city, north western part of Sanandaj-Sirjan metamorphic zone. Rock units outcropped in this area are volcano sedimentary metamorphosed rocks in green ...
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Barika deposit is the first and only recognized gold (and silver) rich – massive sulfide deposit in Iran which is located at 18 km east of Sardasht city, north western part of Sanandaj-Sirjan metamorphic zone. Rock units outcropped in this area are volcano sedimentary metamorphosed rocks in green schist facies, and include association of metaandesite, metatuffite, phyllite and slate rocks, among which the metaandesitic unit (KMv1) is host rock of the deposit. Ore mineral assemblages in stratiform part of the deposit, which contain massive and banded pyrite and barite associated with subordinary silica bands, are very variable in composition and consist of pyrite, sphalerite, galena, stibnite and a variety of sulfosalt minerals and electrum. Ore mineral assemblage in silicic veins in stringer zone, are simpler and consist of pyrite, galena, sphalerite, tetrahedrite and rare chalcopyrite. Average gold and silver grades in stratiform ore are 4.2 and 260 g/t respectively and in silica stringer veins are 0.7 and 30 g/t. Base metal content in both part of the deposit is less than 1%. Lithotectonic study and trace and rare earth elements diagrams associated with Ce/Pb and Nb/U ratios of the metavolcanic rocks in the deposit area indicate that the rocks were generated from a lithospheric mantle source in the active continental margin of the SSZ. A geochemical study of Barika deposit reveals that distribution patterns and correlation coefficient of ore elements in parts of the Barika stratiform ore and stringer zone are completely in correlation with an undeformed massive sulfide deposit. The geochemical documents indicate that despite the metamorphism and highly deformation on the deposit, the primary distribution patterns and proportion of the ore elements are well conserved, as geochemical characteristics of the Barika deformed deposit is as well as correlated with an undeformed gold- rich volcanogenic massive sulfide deposit. However there is clear textural evidence for remobilization of As, Sb, Ag and Pb minerals together with Au in Barika deposit, but, remobilized constituents of the ores do not appear to have moved beyond the margins of the ore bodies and primary metal zonation.
I. Monsef; M. Rahgoshay; M. H. Emami
Abstract
The Late Jurassic to Early Cretaceous Orzuieh volcanic sequence is exposed in the southern part of the Sanandaj – Sirjan Zone. Major and trace element geochemistry shows magma evolution from the transitional to the calc-alkaline series. Clinopyroxene compositions are similar to their composition ...
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The Late Jurassic to Early Cretaceous Orzuieh volcanic sequence is exposed in the southern part of the Sanandaj – Sirjan Zone. Major and trace element geochemistry shows magma evolution from the transitional to the calc-alkaline series. Clinopyroxene compositions are similar to their composition in subduction setting and support a volcanic arc related environment. REE and trace element diagrams show enrichment patterns in LREE relative to HREE and depletion in Nb and Ta elements. This magmatic sequence has been originated from the mantle source with effect of liquids and sediment resulted from the subducting slab. The Orzuieh volcanic sequence is probably originated during the subduction of the Neo-Tethyan Oceanic lithosphere under the Sanandaj – Sirjan Zone, during the Late Jurassic to Early Cretaceous time, in the volcanic arc tectonic environment.
