Home – Home – Jornals – Russian Geology and Geophysics 2001 number 3

This paper deals with study of epigenesis (dolomitization, recrystallization, and dissolution) of carbonate rocks at the Mississippi valley-type Pb-Zn deposits in the Sakha Republic (Yakutia). The average Pb + Zn content in carbonate rocks of the Sardana deposit slightly decreases with increasing dolomite content up to 65% and then drastically increases. This dependence is similar to that between the dolomite content and porosity of the Midale beds in the Charles oil field. This suggests that the paragenetic relationship between dolomites and the Mississippi valley-type Pb-Zn mineralization is due to the formation of an additional pore space as a result of epigenetic dolomitization. In ore occurrences of the Kamenka zone, the content of Zn increases with coarsening crystal grains of the host dolomites to 0.2-0.3 mm. Further recrystallization of dolomites does not cause changes in their Zn content. Outside the ore areas of the Sardana deposit, the Pb and Zn contents have been established to be higher in stylolites as compared with the host carbonate rocks by a factor of 390 and 1270, respectively. Metals in stylolite are suggested to be concentrated from a dissolved bed of carbonate rock. Therefore, the initial contents of metals disseminated in the productive member are estimated.