Mineral microinclusions in glauconite of Bakchar deposit (Tomsk region)

Abstract

Due to its unique properties glauconite is a prospective geological information source. Glauconite is an active natural sorbent. It can accumulate elements in the environment of sedimentation, which subsequently form a new mineral phase within the granules of glauconite. The relevance of the study is determined by the possibility of awareness of sedimentation on the basis and through the study of the matter created by them within the Bakchar deposit. The main aim of the research is to study the mineral microinclusions in glauconite of Bakchar deposit to describe the mineral substrate coming into sedimentation basin. The methods used in the study: samples sieving into granulometric classes with the size more than 1mm, 1…0,5, 0,5…0,2, 0,2…0,1, less than 0,1 mm; electromagnetic separation (EVS 10/5) at 4…2 A; additional cleaning of glauconite grains from magnetic fraction under a binocular microscope; pressed pellet production; scanning electron microscope (TESCAN VEGA 3 SBU) with energy dispersive attachment OXFORD X-Max50 for X-ray spectroscopic analysis. With the help of electron microscopy, microinclusions of gold, silver and other minerals (phosphates, sulfides, sulfates, oxides, and silicates) were found in the glauconites of Bakchar deposit. Mineral associations of microinclusions indicate the occurrence of precious, non-ferrous and rare metals in the sedimentation environment. It is assumed that glauconite as an active natural sorbent «was loaded» by metals and ultrafine terrigenous components on the background of hydrogen sulfide contamination of sediment with microorganisms. These conditions were favorable for forming new mineral phases of sulfides, sulfates and gold. The findings are a sign of potential gold mineralization of glauconite rocks of Bakchar deposit.

Keywords

• glauconite
• gold
• microinclusions
• sulphides
• Bakchar deposit