Admixture-elements and their use as geochemical indicators for search of buried pyrite ores in the Greater Caucasus (Azerbaijan)

Heterogeneous pyritaceous-polymetallic and copper-zinc-pyrrhotine deposits on the South slope of the Greater Caucasus are located in the Lower-Middle Jurassic terrigenous sediments. They were formed under a wide variation of physico-chemical parameters of mineral formation and are characterized by specific mineralogical-geochemical peculiarities. Ore-formation occurred in three stages. In the first stage, massive hydrothermal-sedimentary sulphurous-pyrite ores were deposited. The formation of the second stage of hydrothermal-metasomatic pyrite-polymetallic ores was prior to the intrusion of constant differentiated formation dikes. In the third stage hydrothermal-metamorphogenic copper-pyrrhotine ores were formed. Stratiform pyrite deposits can be characterized by a large variety of textural -mineralogical types of ores and mineral associations, by rich mineral composition and a rather wide geochemical spectrum. As a whole, among the studied admixture-elements (Tl, Ag, Hg as well as B, Li, Rb) one can find accumulating tendency in the above-ore series, near ores with pyrite-polymetallic composition. Other group of elements (Co, Sn, Mn, Mo and Bi) shows accumulation in the under-ore series. Deeper horizons of sandy-clayey rocks are enriched in uranium and potassium while the higher horizons are enriched in thorium above the ore deposit. Distribution peculiarities of such components (Tl, Ag, Hg, Sn and also Mo, Bi, K, U, Th) in the host the rocks of pyrite deposits of Greater Caucasus of South slope allows one to consider them along with ore forming components (Zn, Pb, Cu) as indicator elements for search of buried ore accumulations in the Lower-Middle Jurassic sandy-clayey deposits of region.