Magnetic susceptibility and density characterization of mineralized and non mineralized rocks in the Chirano Gold Camp, Ghana

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Magnetic susceptibility measurements taken on drilled cores from two holes indicate that the core from Paboase deposit had a magnetic susceptibility value within the range of (3.96 – 7.49) x 10 -6 SI and a mean of 5.90 x 10 -6 SI for the non mineralized rocks and magnetic susceptibility within the range (2.29 - 4.58) x 10 -6 SI for the mineralized rocks with a mean value of 3.51.90 x 10 -6 SI. The drilled core from the Akwaaba deposit had a magnetic susceptibility in the range of (5.02 - 12.36) x 10 -6 SI with a mean of 7.37 x 10 -6 SI for the non mineralized rocks and (1.0 – 7.0) x 10 -6 SI with a mean of 4.99 x 10 -6 SI for mineralized rocks. Comparatively, the magnetic susceptibility of the non mineralized rocks from the Paboase concession are high with low assay values within the range of (0.01 – 0.17) ppm while the mineralized rocks have low magnetic susceptibility with high assay values within the range of (1.25 – 17.4) ppm. The assay result for the Akwaaba deposit follows the same trend as that of Paboase deposit, low from (0.00 – 0.04) ppm within the non mineralized rocks but high assay values of (0.41 – 10.13) ppm within the mineralized rocks. There was a general negative correlation between the assay values and the magnetic susceptibility values. The magnetic susceptibility values decrease drastically for rocks with high gold assay values while those with very low gold assay values generally have high magnetic susceptibility values. Selected rocks from the two holes on which density measurements were carried also produced densities around the means of 2698.56 kg/m 3 for basalt and 2704.11kg/m 3 for tonalite from Paboase deposit, 2959.57kg/m 3 for basalt from Akwaaba deposit These correlations are strong signals that can be used to delineate mineralized zones in the area with a prove backed by the use of other geophysical method.
A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for Master of Science, 2013