Geochemistry of Trace and Rare Earth Elements and Their Use in Exploration of Gold-richVolcanogenic Massive Sulfide Mineralization in Barika Area

Category Economic geology & mineral exploration
Group GSI.IR
Location The 24 Symposium of Geosciences
Author Yarmohammadi.A,Rastad.E,Shamsa.M.J
Holding Date 15 August 2007

Abstract

Barika deposit occurred in a Cretaceous metavolcano-sedimentary sequence at           northwestern Sanandaj-Sirjan zone. Gold-rich volcanogenic (VMS) massive sulfide mineralization occurred in a meta-rhyolite to rhyolitic tuff. Major ore elements in this mineralization, in order of abundance, are Au, Ag, Zn, Pb and Cu. Other high anomaly elements consist of Sb, As, Hg and Cd. All of these elements have positive correlations with each other in ore. Also, Tl has high positive correlation with other elements in the ore horizon. Tl content in the footwall and hangingwall rocks is low (<10); whereas, it reachs its highest amount (60ppm) in the ore horizon. Based on Smith and Huston (1992) and Large et al. (2001), increasing of Tl content from footwall toward ore horizon and  its decreasing in hangingwall rocks, could be useful in distinguishing ore horizon stratigraphic position. REE pattern in altered andesitic to trachyandesitic footwall rocks is flat or has a very low dip and has a clear negative Eu anomaly and weak depletion in REE content. REE Pattern in host rock and the ore is irregular with a large positive Eu anomaly. REE Pattern in non-altered hangingwall meta-tuffs is flat with negative Eu anomaly. Based on Graff (1977) and Bence (1983), the negative Eu anomaly in   the footwall and hangingwall altered rocks and positive Eu anomaly in the ore, could be useful in lithogeochemical exploration for gold-rich VMS deposits in the Barika area.

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