TiO₂–Zr–Th–Y–rare‐earth elements ore deposit in unconsolidated fine‐grained sediments from Tongo Gandima in the Bétaré Oya Gold district, Eastern Cameroon

Abstract

is an area located in the southeastern part of the Bétaré Oya Gold district (Eastern Cameroon). Geochemical investigations on rare metals (TiO 2 , Th, Y, and rare-earth elements [REE]) were carried out on sample types (source rocks, unconsolidated fine-grained sediments, and concentrated sediments) using X-ray diffraction (XRD), X-ray fluorescence (XRF), inductively coupled plasma-mass spectrometry (ICP-MS), and scanning electron microscope equipped with EDAX spectrometer (SEM-EDS) methods. In this study, five layers of river terraces were selected (organic matter layer, clayey layer, fine sandy layer, coarse sandy layer, and gravel layer). One of them, the gravel layer, is mineralized. TiO 2 , Zr, and REE are more enriched in monzonites than in granites. Unconsolidated sediments derive mainly from the erosion of weathered materials developed on monzonites and granites. The mineral assemblage of fine-grained sediments from the gravel layer is muscovite, kaolinite, quartz, rutile, smectite, and others, and the average concentrations in Th, Zr, and Y are high. Fifty

Rare earth elements in surface waters and sediments of the Mgoua watershed, south western Cameroon

“…The high water flushing conditions in the study area prevent the accumulation of concentrated acidic solutions in these different waters and reduce the dissolution and mobilization of resistant REE bearing phases in the Mgoua Basin waters. Such conditions favor the enrichment of REE in the sediments and the distribution of REE according to the relative elemental composition of the REE-bearing minerals (e.g., apatite, monazite) and the total REE balance in the surrounding sedimentary rocks (Ngueutchoua et al 2019 ; Ndjigui et al 2021 ).…”

“…Rare earth elements are composed of fourteen naturally occurring elements ranging from lanthanum (La) to lutetium (Lu). They are called “the lanthanides” and are known to have the tendency to occur in the same ores (Armstrong-Altrin et al 2018 ; Ongboye et al 2019 ; Ndjigui et al 2021 ; Liu et al 2021 ). Generally, in the environment, light REE (LREE: La, Ce, Pr, Nd, Sm, Eu, Gd) tend to have higher affinities for fine and coarse particles, while heavy REE (HREE: Tb, Dy, Ho, Er, Tm, Yb, and Lu) are more easily complexed by dissolved ligands (Censi et al 2004 ; Deng et al 2017 ).…”

“…These characteristics lead to several geochemical applications of REE. For example, once the concentrations of REE in a sample are normalized against appropriate standards (e.g., chondrite, PAAS, and UCC), anomalies in the abundance of one element relative to other REE can be quantitatively assessed and then used, for example, as tracers (Ekoa Bessa et al 2018 ; Ndjigui et al 2013 , 2021 ; Armstrong-Altrin 2020 ; Dang et al 2021 ; Ramos-Vázquez and Armstrong-Altrin 2021a , b ).…”

“…For instance, permanent magnet production caused 30% of rare earth production (Binnemans et al 2013 ). Furthermore, although global demand for REE is increasing, supply is declining and recycling of REE-containing waste is becoming an increasingly important activity (Schulze and Buchert 2016 ; Cox and Kynicky 2018 ; Ndjigui et al 2021 ; Armstrong-Altrin et al 2021a , b ). As a result, REE contamination is no longer limited to areas in the immediate vicinity of mining operations, but has also been reported in surface waters and sediments that are not in close proximity to mining activity (Tepe et al 2014 ; Bonnail et al 2017 ; Ongboye et al 2019 ).…”