Application of remote sensing and GIS mapping to Quaternary to recent surficial sediments of the Central Uranium district, Namibia

The arid conditions in the study area within the central Uranium district of the Namib Desert are suitable for remote sensing analysis. This research applies integrated remote sensing and GIS methods to various datasets including ASTER and Hymap hyperspectral, and includes field-validation to differentiate between previously undifferentiated Quaternary to Recent surficial sediments. Comparative assessment of the remote sensing and GIS derived geological datasets is performed, and field mapping used to the constrain results. In conjunction with the integrated mapping, the distribution of uranium in the area through natural processes such as wind and fluvial systems, as well as factors associated with mining and exploration are investigated. In addition to baseline geological data, the study provides useful information for the understanding of secondary uranium mineralisation, and for environmental monitoring of uranium activity

Three Horizons for Future Geoscience

Geoscience, along with other scientific disciplines, is being increasingly challenged on how it can best confront key global challenges, such as climate change, food insecurity, biodiversity loss, human conflict and migration, and persistent poverty. But its traditional association with exploitation of the planet’s natural resources for energy and materials links it with contemporary concerns around unsustainable human practices, arguably fueling a growing disenchantment that is most evident in declining enrollment in university geoscience courses in many countries. Therefore, a fresh re-framing of the geoscience’s relationship to society would seem to be urgently needed. In response to this need, we introduce the “Three Horizons” concept for visualizing paradigm change in complex systems as a tool to explore how the future global geoscientific mission might be re-imagined. Using this conceptual framework, we consider three parallel pathways – “business as usual” (horizon 1), “entrepreneurial” (horizon 2) and “visionary” (horizon 3)—that offer alternative narrative trajectories for how geoscience and geoscientists might serve society’s grand challenges

Regolith characterization using ASTER data in the Central Namib, Namibia

[Extract] Multi-spectral remote Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor is an inexpensive, powerful remote sensing tool for measuring mineral group abundance and composition of surface materials [1]. The published geological map of the central Namib Uranium District (CNUD) contains tracts of Quaternary cover sediments that are largely mapped as an undifferentiated unit [2]. Hyper-arid to semi-arid environments with minimum vegetation cover are ideal for the use of spectral remote sensing technologies. The study area is located within the central part of the Namib Desert along the central west coast of Namibia (Figure 1a). The published geology of central Namib comprises Palaeoproterozoic gneissic basement and Neoproterozoic Damara Supergroup metasediments, and associated intrusive rocks, overlain by Quaternary to recent surficial deposits [2, 3]. The main aim of this study was to mineralogically discriminate and map the undifferentiated Quaternary regolith using ASTER data (Figure 1b). Mapping the surficial cover sediments has potential benefits such as contributing to the understanding of the provenance of the surficial sediments and providing enhanced base-line data that can further aid mineral exploration in the region

Remote Sensing Exploration of Nb-Ta-LREE-Enriched Carbonatite (Epembe/Namibia)

On the example of the Epembe carbonatite-hosted Nb-Ta-LREE deposit, we demonstrate the use of hyperspectral reflectance data and geomorphic indicators for improving the accuracy of remote sensing exploration data of structurally-controlled critical raw material deposits. The results further show how exploration can benefit from a combination of expert knowledge and remotely-sensed relief, as well as imaging data. In the first stage, multi-source remote sensing data were used in lithological mapping based on Kohonen Self-Organizing Maps (SOM). We exemplify that morphological indices, such as Topographic Position Index (TPI), and spatial coordinates are crucial parameters to improve the accuracy of carbonate classification as much as 10%. The resulting lithological map shows the spatial distribution of the ridge forming carbonatite dyke, the fenitization zone, syenite plugs and mafic intrusions. In a second step, the internal zones of the carbonatite complex were identified using the Multi-Range Spectral Feature Fitting (MRSFF) algorithm and a specific decision tree. This approach allowed detecting potential enrichment zones characterized by an abundance of fluorapatite and pyroxene, as well as dolomite-carbonatite (beforsite). Cross-validation of the mineral map with field observations and radiometric data confirms the accuracy of the proposed method