Age and sources of low-sulfide gold-quartz mineralization of the Karalon gold ore field (North Transbaikalia, Russia): results of isotope-geochemical (Rb-Sr and Pb-Pb) studies

The article presents the results of studying the Rb–Sr isotope system of ore-bearing granitoids, apogranite metasomatites and hydrothermalites of the Verkhnekaralonskoye gold deposit, as well as the Pb-Pb isotope system in galena of the gold-quartz low-sulfide mineralization of the Karalonskoye gold ore field. Three groups of ore objects with different Pb isotopic compositions of galena associated with varying contributions from mantle and ancient crustal sources have been identified. The isotope characteristics of Pb in galena of the Verkhnekaralonskoe deposit indicate its genetic relationship with ore-bearing juvenile granites, whose age of ~ 600 Ma may be close to the age of the earliest stage in the formation of gold–quartz mineralization. The ancient crustal source is common for the leading gold deposits of Northern Transbaikalia and is characterized by the parameters of the continental crust of the Siberian craton at a time of 500–600 Ma. The rearrangement of the Rb–Sr system in the studied rocks and minerals of the Verkhnekaralonskoe deposit and the redistribution of Pb isotopes in galena of the Vodorazdelnaya ore zone of the Karalonskoe ore field at the turn of 290–250 Ma have been established. Isotope data show that in the geological history of the Verkhnekaralonskoe deposit and the Karalonskoe ore field, the formation of gold mineralization had a long multi-stage character and was accompanied by the regeneration of primary ore concentrations.