Geochemical exploration using portable X-ray fluorescence (pXRF) analysers in the Giraúl region (Namibe, SW Angola)
DOI:
https://doi.org/10.21701/bolgeomin/136.2/005Keywords:
Critical element exploration, Geochemistry, Portable X-ray fluorescence (pXRF), Pegmatites, AngolaAbstract
A major geochemical exploration campaign was carried out in SW Angola during the PLANAGEO project, including the analysis of rock, soil, and stream sediment samples using in situ portable X-ray fluorescence (pXRF) analysers. The present work focuses on the analytical results obtained in the area of the Giraúl Pegmatitic Field, a world-class Li-rich pegmatitic dike swarm, as well as on adjacent areas with potential for critical element mineralisation. In situ pXFR geochemical analyses revealed high Nb and Ta contents in the pegmatites of Giraúl, in the surrounding soils, suggesting a clear relation to LCT pegmatites. The most important Nb contents are found in denudated soils from the Cretaceous latite volcanic units of the Bero Volcanic Complex, reaching values up to 896 mg/kg. This work has enabled to define some areas of special interest: (a) the Giraúl Pegmatitic Field, where significant anomalous concentrations of Nb-Ta (Li-Be) occur; (b) the amphibolitic units of the Namibe Group metasediments and other mafic Palaeoproterozoic intrusions, which show potential interest for base metal (Cr-Ni-Co, Cu) exploration; and (c) the Cretaceous volcanic rocks of the Namibe Basin, in the coastal region, which hold potential interest for Fe-Ti (V).
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