Fractionation of platinum group elements in gold deposits in Uzbekistan

Geoscience Research Reports 42, 2009 (GRR for 2008), pages 240–244

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Abstract

Ores and host rocks from epithermal Au-Ag deposits (Kyzylalma and Kochbulak), intrusion-related gold deposits (Charmitan and Guzhumsai), and orogenic gold deposits (Daugystau, Amantaytau, Vysokovoltnoye, and Myutenbai) in Uzbekistan have been studied for their PGE and Au contents. No anomalous PGE concentrations were detected in the studied ore samples. In the ore samples from the epithermal deposits, low Pt (max. 7.5 ppb) and Pd (max. 2.6 ppb) values, the shape of chondrite-normalized PGE patterns, and Pd/Ir = 20.5, indicate a crustal source for the PGE. Among the intrusion-related gold de- posits, maximum Pt (19.3 ppb) was found in the Guzhumsai ore and maximum Pd (3.03 ppb) in the black shales that host the Charmitan intrusion. At Guzhumsai, such low values and the types of chondrite-normalized PGE patterns suggest intrusive host rocks as a source of PGE. Within the orogenic gold deposits hosted in black shale, very high values of Pt (351 ppb) were found in the barren black shale from Myutenbai and Pd (9.4 ppb) in the barren black shale from Vysokovoltnoye. Average PGE concentrations in ores and the shape of chondrite-normalized PGE patterns indicate the black shales as the source of PGE.