Browsing by Author "Mkinga, Bartholomew Ambrose Msambichaka"

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    Geological and environmental study of Kirondatal gold mine on the Iramba plateau
    (University of Dar es Salaam, 1997) Mkinga, Bartholomew Ambrose Msambichaka
    Kirondatal gold deposit is an epithermal high grade deposit with low tonnage. Its mineralization is controlled mainly by type of lithology, shear zones and intrunsives. Rich ores are found in zones where: shear zones of different orientations meet, the aplitic bodies intersect and link with the master shear zones. In areas where these conditions combine, richest ores are found. Kirondatal gold deposit is hosted by mafic volcanic rocks, although granitic rocks are also present in its vicinity. The granitic rocks that are found within the mafic volcanic series present in its vicinity. The granitic rocks were the suppliers of heat which set the metamorphic waters in motion and in such process gold was mobilized, transported and deposited in shear zones. Geochemical data indicate that the mafic volcanic series consist of two groups of basaltic rocks that formed in different environments, but were brought together due to tectonic movements. The first group was probably formed in accretionary prism of the subduction zone near the plate margin. The second group formed in oceanic island. The environmental study has elucidated the impact of gold mining activities around the area of Kirondatal gold mine. Heavy metal contamination and physical land degradation by deforestation, pitting and soil erosion are among the major environmental impacts at the mine. Almost all heavy metals analyzed show concentrations above permissible levels either in stream sediments, mine tailings and soil, or in all three media. Arsenic, chromium, cobalt, and copper are concentrated above permissible levels in stream sediments, mine tailings and farming soil. Cadmium concentration is above permissible levels in farming soils, but in other media falls below the maximum permissible level. Lead shows concentration above permissible values in mine tailings only. In water samples all metals have concentrations below the maximum permissible values. Arsenic concentration in stream sediments ranges between 93 and 764 ppm, in soil ranges from 89 to 1255 ppm, and in water is in the range of 0.43 – 53 ug/1. Chromium is in range of 196 – 294 ppm in stream sediments, 55 – 310 ppm in soil, and 0.12 – 19 ug/1 in water. Cobalt concentration in stream sediments ranges from 41 to 115 ppm, in soil is in range of 7 to 138 ppm. Concentration of copper in stream sediments is within the range of 35 – 71 ppm, and in soil is in the range of 17 – 116 ppm. Cadmium concentration ranges from 0.4 to 1.4 ppm in stream sediments, 0.4 to 1.2 in soil and 0 to 0.2 ug/1 in water. Concentration of lead in stream sediments ranges from 25 to 148 ppm, 19 to 91 ppm in soil, and 0.1 to 3.92 ug/1 in water.