Conditions of formation and stages of mineralization of the Pyazbashi gold-sulfide-quartz deposits (Leser Caucasus, Azerbaijan)

Abstract

We analyzed the conditions of the formation and stages of mineralization of the Pyazbashi gold-sulfide-quartz deposits. The deposits were determined to contain three structural-morphologic types of ore bodies: gold-quartz-sulfide – veinular, gold-bearing veins and the strip of gold-bearing metasomatites. We determined that in the deposits, quartz-pytire, quartz-carbonate and carbonate veins with gold and polymetal mineralization are confined to the volcanic-tectonic structures. Those volcanic-tectonic structures have various fracture systems, are complicated and have been inherited by later changes that occurred after the formation of the Lower and Middle Eocene volcanogenic complexes, and some of them have been embedded again. We de- termined that gold ore mineralization in the deposits is related to various hydrothermal-metasomatic formations and has developed in complex multy-stage process. Interaction of various veins and minerals that comprise them allow us to assume the following pattern in the sequence of the mineralization stages (from early stage to later stages): 1-quartz-sericite; 2-quartz-pyrite-molybdenum; 3-quartz- pyrite-gold ore; 4-quartz-polymetal; 5-carbonate. Gold-ore bodies are mainly complicated by aggregates of quartz-pyrite-gold ore stage of mineralization, which is the productive stage. We present the results of chemical analysis of native pyrite and chalcopyrite. We determined that native gold occurs as small, regular-shaped bodies in pyrite grains. In the veinlets of chalcopyrite, it is usually confined to marginal parts.