Abstract:

The paper introduces a number of new research results on the characteristics of lead - zinc ores in Phia Dam - Khuoi Man areas based on the application of traditional geological methods, combining the method of researching material composition and method statistical maths. In the study area, there are two forms of ore bodies with characteristics described as below: the first form consists of ore bodies developed along the stratabound bedding surface, are mainly distributed in either anticlinal structures (i.e. Phia Dam region) or cuesta (i.e. Khuoi Man region) and the second form consists of ore bodies in lodes, filled in cracks or zones of fracture along the northwest – southeast faults. Primary ore minerals are mainly galena, sphalerite, pyrite, chalcopyrite, etc. and gangue minerals are calcite, dolomite, and quartz. Ore structures are nests, veins, disseminated veins, banded, speckled, or sometimes breccia - like ones. The relevant and controlling factors of lead-zinc mineralization in Phia Dam - Khuoi Man region are the northwest - southeast fault system and the lithostratigraphy. Ores are of either mesothermal or epithermal deposits (temperatures varies from 162 to 308 degrees Celcius), with a specific symbiotic combination of quartz - sphalerite - galena - chancopyrite.