Effects of environmental parameters on metal dispersion patterns in stream sediments from the lead-zinc belt, Benue Trough, Nigeria: using factor analysis

Abstract

Pb, Cu, Zn, Mn, Fe, pH and organic matter (OM) data on 350 reconnaissance stream sediments obtained from the lead-zinc belt of Nigeria's Benue Trough around Abakaliki are examined by R-mode factor analysis, with the objective of isolating the significant factors accounting for the sample composition as derived from mineralization and environment. The orthogonal varimax solution yields a three-factor model that accounts for 72% of total data variance. Factor 1, an OM-Pb-Cu factor shows the influence of organic matter on Pb and Cu dispersion in the stream sediments. Factor 2, a Zn-Fe factor shows the chelating effect of iron oxides on Zn in an oxidizing environment. Factor 3, a pH-Mn factor is explained as depicting the effect of pH on Mn precipitation in areas with calcareous shale horizons. The results have aided in isolating effects of surficial processes on metal dispersion within a complex tropical environment. Thus in the search for polymetallic deposits in tropical terrains, the presence of organic matter and iron oxides are factors detrimental to the exploration for Pb and Zn respectively. The pH is of no importance for these two elements although it affects Mn precipitation in localized environments.