Abstract:
The main aim of this dissertation was to identify pathfinder elements for gold and generate
new gold targets for further exploration at Chirano Gold Mining Area. A geochemical data
was generated from 521 soil samples which were analysed for 51 elements and evaluated
using multivariate statistical methods. Principal Components and Factor Analyses were used
to reduce the data into two groups and Cluster Analysis conducted to find element
associations hence pathfinders for gold. Anomalous trends were determined on Ranked
Variable Maps and Gridded Maps and used in selection of targets. Soil samples taken from
the study area were analysed by ICP-AES (inductively coupled atomic emission
spectrometry) for trace elements/base metals and ICP-MS (inductively coupled mass
spectrometry) for gold. In order to guide in the determination of anomalies and identification
of pathfinders for gold, descriptive statistics, correlation matrices, probability plots, ranked
variable maps and gridded maps were made. Ranked variable maps and gridded maps created
in IoGAS showed that elements such as La, Mg, Mn, Ba, Th and Ti have strong anomalies
whiles Ca, Cd, In, Sn, S, Sc, Sr, V, Zr and Y have weak to moderate anomalies that correlate
with the Chirano Shear Zone. Gold mineralization along the Bibiani shear zone, on the other
hand, was clearly marked by strong anomalies of As, Cs, Sb and W and also weak to
moderate anomalies of Na, Cd, S, Sc, Sr, V and Zr. Others such as Bi, Li, Re, Se, Ta, Te, Sc,
U, B and Li were not anomalous in the project area. B and Li were depleted whiles Ta had
high but localized values. Principal Components, Factor and Cluster Analyses were
conducted in Minitab software. The first six Principal Components extracted 55.8 % of the
explained variance in the variables. The first principal component extracted 21.3% of
variability with large positive loadings from Ag, Al, Fe, Sc, Th, U, V, Zr, In and Sn which
were linked to the underlying felsic intrusive rocks such as tonalite, granodiorite and quartz-
feldspar porphyry. The second principal component also extracted 10.2% of variance and had
large negative loadings from Cu, Ni, Zn, Ba, Co, La, Mg, Mn, Sr, Ca and Cd which were
linked to the underlying mafic rocks such as basalts, dolerites and diorites. Cluster Analysis
also reduced the whole data to six clusters. The first cluster or the gold group consisted of
Au, Mo, W, Re, B, Ta, Ce, Tl, Y and Be. Pathfinders for gold in the area under investigation
were identified as Mo, W, Re, B, Ta, Ce, Tl, Y and Be. Twenty gold targets were identified
including thirteen from Chirano North Gold project and seven from the Chirano Mining
Lease. These targets must be ranked according to priority for further exploration work,
preferably RC drilling.
