GENESIS OF SULFIDES AND GEOCHEMICAL ANOMALIES AT THE PERMAFROST base
V.N. Makarov1, B.P. Pod’yachev2
1Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
2JSC “Yakutskgeologiya”, Yakutsk, Russia
Keywords: geochemical anomalies, sulphides, carbonate and terrigenous deposits, permafrost base, groundwater
Abstract
The results of drilling a series of boreholes in Central Yakutia are discussed. At a depth of 250-300 m, in the Cambrian carbonate rocks and in the Lower Jurassic terrigenous sediments, a zone of sulfide mineralization with contrasting geochemical anomalies was discovered. The zone of sulfide-saturated rocks is localized in the interval from the permafrost base to the table of subpermafrost groundwater; it extends laterally for 80 km and does not depend on the composition and age of sediments. The development of sulfide mineralization in the Cambrian carbonate rocks and Lower Jurassic terrigenous sediments was due to cryogenic processes during sharp and strong cooling of the climate. In that period, the groundwater of bicarbonate-sodium composition depleted of lithochalcophile elements was formed. This was accompanied by the formation of the zone of sulfide mineralization and contrasting anomalies of Mo, V, Ni, Cu, Li, Sn, Ta, Nb, Ge, and Au at the permafrost base.
|
