Geological-geophysical criteria for the prospecting and exploration of rare metal-titanium placer deposits: Evidence from the Transural region

The results of study of the Umyt’ya rare metal-titanium placer in the Transural province of West Siberia (Khanty-Mansiisk autonomous district) are presented. Lithological features of the placer-hosting Oligocene sediments were used to identify three horizons with different formation conditions and placer metal potentials. Lithofacies analysis of rocks of the upper horizon was accomplished. Comparison of the obtained results with the geophysical information (gamma and electrical logging) makes it possible to determine geological-geophysical criteria for the prospecting and exploration of rare metal-titanium placer deposits. It has been established that the gamma activity of placer-hosting rocks have a high and stable correlation with their composition (the content of minerals of the Zr-Ti assemblage included) and makes it possible to recognize separate sectors with placer bodies of mainly shallow-marine type. Electrical properties of rocks are less representative for the local prospecting, but they provide insight into the placer metal potential of separate rock horizons. Based on the identified criteria, prognostic assessment is given for the placer metal potential of deep horizons in the productive sequence of the Umyt’ya placer.