GEOCHEMICAL CHARACTERISTICS OF MANGANESE MINERALIZATION FROM THE POZHAREVO DEPOSIT, WESTERN SREDNOGORIE ZONE, BULGARIA

Abstract

The increased demand for raw materials requires to reassess some deposits that were not of economic interest in the past. Complex of modern geochemical and mineralogical methods (SEM-EDS, LA-ICP-MS, QUEMSCAN) are used to study the ore mineralization in the small scale Pozharevo manganese deposit, Western Srednogorie Zone, Bulgaria. The deposit is formed in the contact zone between Late Cretaceous andesite pyroclastic rocks and overlying volcanogenic-sedimentary rocks. Manganese mineralization forms colloform textures of alternating compositions from manganeserich phases (birnessite, hollandite, pyrolusite etc.), mixed silicon-manganese phases to silicon-rich phases and often brecciates volcanic clasts. In situ LA-ICP-MS study of trace elements shows significant amounts of Cu, Li, As, Sr, Mo, Ba, W, Tl, REE, some of them defined as critical raw materials. QUEMSCAN study demonstrates join deposition of Mn, K and Ba with volcanogenic-sedimentary origin while later pyrolusite probably is hydrothermal. Mineralogical and geochemical characteristics show hydrothermal-sedimentary origin of Mn mineralization but also it has common features with modern deep-sea polymetallic nodules and proposes similar paleogeodinamic environments. Our study shows that the Pozharevo manganese deposit has good potential for prospecting of critical elements.