Geochemical characteristics of stream sediments as a preliminary tool for exploration in the Mbengwi area, Northwestern Cameroon

Abstract

The Mbengwi area is located along the Cenozoic volcano-plutonic Cameroon Volcanic Line (CVL) within the Northern Domain of the Pan-African Neoproterozoic Fold Belt of Cameroon. Important magnetite filings are continuously recovered in the area along drainage trails. The source of this concealed mineralization has not been established. A total of ten active stream sediment samples were recovered and analyzed for major and trace elements by the inductively coupled plasma mass spectrometry (ICP-MS) technique. The mineralogical population (phases) of the heavy mineral concentrates consists of zircon, rutile, quartz, and opaque mineral phases, with angular to sub-rounded morphologies indicating moderate to long transport distances. Sediment geochemistry shows high contents in Fe₂O₃ up to 37.43 wt.%, with low contents in Al₂O₃, MgO, CaO, Na₂O, and K₂O. The concentrations of siderophiles (e.g., Fe, Bi, Co, Cr, Ga, Mn, Mo, and Ni) and chalcophiles (e.g., In, Sn, and Hg) are slightly elevated with respect to their average upper continental crust values. The spatial distribution of iron and other elements is presented as point symbol maps, and the data is analyzed using multivariate statistics. From the principal component analysis (PCA), the Ag-Hg-Tl-Mo-As-Sb-Cd-Se-Pb-Au-In-Nb, as well as the Zn-Co-Ga-Mn-Ni-In-Fe-Cu factors, point to the presence of a hydrothermal fluid circulation in the area associated with possible Au-Ag-Mo and Fe-Cu mineralization. Ag, Hg, Mo, and As could serve as a pathfinder for Au in the area. The single element factor with Sn reflects the occurrence of cassiterite host rocks in the area. The sediments from the Mbengwi area were deposited under humid tropical and equatorial climates. The geochemical parameters (CIA, CIW, and PIA) point to a strong weathering of feldspar-bearing source rocks. The dominant mafic to intermediate igneous provenance suggests that mica schists, granodiorites, monzogranites, monzonites, and basanites could be potential source rocks in the area.