Geochemistry of stream sediments from Eséka area (SW Cameroon): implications for surface process assessment and precious metals (Au, Pd, and Pt) exploration

Abstract

Stream sediment geochemical data from SW Cameroon were examined as a contribution for surface process study and preliminary exploration of Au, Pd, and Pt. Samples were collected from both active and overbank stream sediments. Samples were analyzed for mineralogy, major and trace elements including rare-earth elements, and Au, Pd, and Pt concentrations. The sediments are mainly made up of quartz, gibbsite, goethite, and kaolinite. Their chemical composition is dominated by SiO 2 , Al 2 O 3 , and Fe 2 O 3 . They are geochemically classified as Fe-sand and derive from moderate to intense weathered sources which are the local surrounding rocks. Variability in the chemical composition could be attributed to weathering and hydrodynamic sorting of sediments during transport. Trace and rare-earth elements are sparsely present in river sediments in the Eséka area. The high Zr contents could reveal high proportion of zircon as a resistant mineral to weathering. The normalized REE patterns show relative HREE enrichment due to the fact that zircon preferentially incorporates HREE. The variable La/ Sc, La/Co, Th/Sc, Zr/Cr, LREE/HREE ratios, and Eu-anomalies suggest that the stream sediments may have originated from mixed felsic and mafic source contributions. Gold, Pd, and Pt have variable contents with the highest contents in the active stream samples. The active stream sediments are the appropriate tools for geochemical Au surveys in humid forest regions. Despite the low contents in stream sediments, some sampling points are favorable for further Au, Pd, and Pt exploration in their upstream sources. The clayey materials should be favorable for Pd and Pt accumulations.

Curie Point Depth from Spectral Analysis of Magnetic Data in Potiskum and Environs, Yobe State, Nigeria

“…According to Fairhead (2023), the Cretaceous Rift system of West and Central Africa extend for over 4000 km from Nigeria northwards into Niger and Libya and eastwards through southern Chad into Sudan and Kenya. The Chad Basin with an area of about 2,335,000 km 2 (Sababa et al, 2023) and occupies a vast area at an altitude of between 200 m and 500 m above sea level in Central Africa. The Bornu Basin (Nigerian sector of the Chad Basin) makes up approximately 10 percent of the basin.…”

Alluvial sediments in Bol area (Lake Chad Basin): implications for source area-weathering and tectonic settings

“…Goethite and to a lesser extent rutile are also signi cantly represented (Table 2). The mineral composition of alluvial sediments re ects the regional soils (Sababa et al, 2022).…”

“…The geochemical features of alluvial sediments are governed by several factors such as source rock composition, palaeoclimate, maturity, transportation, weathering source conditions and tectonics (Taylor and McLennan, 1985;Tian et al, 2020;Huyan et al, 2021;Sababa et al, 2022). The morphology of alluvial sediments and the microtextures of their quartz grains give reliable information on the origin, the transport and the paleoenvironment (Hossain et al, 2020; Armstrong-Altrin et al, 2015; Ekoa Bessa et al, 2021a).…”

“…Trace and partial rare earth element compositions (in ppm) of the alluvial sediments from Bol area (Lac Chad Basin).Conversely, Al 2 O 3 is strongly bound to Fe 2 O 3 and LOI due probably to their a nity for clay minerals(Bhuiyan et al, 2011;Sababa et al, 2022). Loss on ignition (LOI) increases with the degree of weathering as a result of clay minerals formation.…”