Orenburg State University, Orenburg, Russia:
G. A. Ponomareva, Associate Professor, Candidate of Geological and Mineralogical Sciences, galy.ponomareva@mail.ru
A. A. Ponomarev, Post-Graduate Student

The Early Permian halogen formations are widely spread in the territory of the Orenburg Region. The thickness of the rock-bearing strata grows southward and southeastward, and reaches maximum values in the Pre-Ural downfold area. This study focuses on distribution patterns of noble metals in halogen strata in the Southern Urals. Geochemical sampling of the test halogen strata in the Orenburg Region was composed of the Iletsk salt deposit samples and cores from the oil and gas reservoirs in the Sakmara–Ilek, Southern Buzuluk, Sol-Iletsk and Teplovsko–Derkul (north wall of Pre-Caspian Syncline) provinces, and was supported with the relevant geological documentation. The results obtained by the authors in detection of noble metals in rock salt point at their nonuniform distribution. The highest concentrations of platinum (3128 mg/t) and gold (2064 mg/t) occur at halite in the Peschanoe oil reservoir. The maximum silver content (3079 mg/t) is observed in rock salt in the Vershinovskoe oil reservoir. The highest palladium concentration (248 mg/t) is a feature of the Akobinsk gas reservoir. The lowest concentrations of platinum (43 mg/t) and palladium (3 mg/t) are found in the samples from the Iletsk salt deposit. The concentrations of gold, platinum and palladium vary the most of halite in the oil and gas reservoir. In the Iletsk rock salt samples, the ranges of the platinum and palladium concentrations are lower by an order of magnitudes. This may be reflective of the presence of a geochemical barrier at the salt–oil interface. It is found that all noble metals have higher content. The detection of noble metals in the salt-bearing strata in the Orenburg’s Urals have the applied relevance as the obtained results demonstrate interaction between the increased concentration of metals, halogenesis and salt tectonics phenomena.

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