ASSESSMENT OF UNDISCOVERED COPPER RESOURCES IN CENTRAL EURASIA AND RUSSIA

USGS scientists, working with international cooperators from government, industry, and academia, are conducting a global mineral resource assessment to outline the regional locations and estimate the probable amounts of the world’s undiscovered resources of copper. The assessment delineates areas (permissive tracts) where undiscovered deposits may be present within ~1 km of the surface, based on deposit-type characteristics. The Central Eurasia-Russia region hosts world class porphyry copper and sediment-hosted copper deposits, as well as undeveloped prospects and active exploration projects. The region is especially challenging for mineral-resource assessment due its complex and incompletely resolved tectonic history. Mapped distributions of magmatic arc-related rocks and mineral-deposit and occurrences databases form the basis for delineating tracts for porphyry copper deposits. Permissive tracts for sediment-hosted copper deposits outline geographic areas within sedimentary basins that include carbonaceous and/or pyritic sedimentary rocks and generally stratigraphically lower hematitic or formerly hematitic continental clastic sedimentary rocks and/or flood basalts. Tracts may include known sediment-hosted copper deposits and prospects as well as overlying rocks of other lithologies that form thin cover. Geophysical data and available exploration data are used to refine tracts. Data are evaluated, and if possible, probabilistic estimates are made of expected numbers of undiscovered deposits within a tract. Estimates are combined with grade-tonnage models in a Monte Carlo simulation to provide probabilistic estimates of contained metal. Permissive tract boundaries (at a scale of 1:1,000,000) and locations of known deposits and significant prospects are prepared in a GIS; regional reports document data sources and the rationale for tract delineation and estimates. Focus areas for porphyry copper deposits include: the Tethys region, the Urals, Kazakhstan-Uzbekistan-Kyrghyzstan, Transbaikalia (Russia-China-Mongolia), and the Russian Far East. Focus areas for sediment-hosted copper deposits include the Kodor-Udokan-Ugui basin of southern Siberia and the Chu-Sarysu and Teniz basins of Kazakhstan.