Application of Termitaria Geochemistry to Iron Oxide Copper Gold Exploration in the Kitumba District, Central Zambia

Abstract

Identification and delineation of deeply buried mineral deposits has gained importance with the continuous increase in demand for commodities, specifically regarding Iron Oxide Copper Gold (IOCG) deposits, because of the multitude of metals they commonly contain. Termitaria offer an excellent sampling medium because the material they are comprised of includes inorganic detritus from depths down to 70 metres, depending on water table depth. Composite sampling of termitaria has been the standard method with no delineation of which portion or which grain size of termitaria offer the best results. Furthermore, no known studies have focused the application of termitaria sampling as an exploration method for IOCG deposits. Throughout the research conducted in this study, optical mineralogy, scanning electron microscopy and X-ray diffraction were utilized to distinguish the mineralogy of termitaria samples. High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) was utilized to ascertain the differences of aqua regia and four-acid digestion for the bulk geochemistry of various grain size fractions including clay, <63 µm, 63-125 µm, 125-250 µm, 250-500 µm, 500-1000 µm, and >1000 µm. Utilizing bivariate scatter plots, stacked cluster columns, and logarithmic line graphs, relationships among the elements determined that aqua regia and four-acid digestion follow similar trends, albeit lower concentrations were found with aqua regia. Standard deviation of sample groupings was utilized to express homogeneity and heterogeneity among grain size fractions and termitary sample locations. It was found that the clay size fraction held the highest concentrations for elements often associated with IOCG deposits, including Co, Cu, La, Mo, Sb, U, and W. It was also discovered that the clays had anomalous concentrations of Ba, Bi, Cr, Cu, Fe, K, Mn, Mo, Tl, and W in comparison to background values and Bi, Co, Cu, Ge, Mo, Sb, SN, U, V, and W in comparison to average crustal abundance. Composite sampling of termitaria is supported in this study with no evidence that the top, bottom, or inside of the mound has consistently higher element concentrations.