Within the framework of this research, the complex geological history of the Pan African-Volta basin has been systematically reconstructed. Based on a broad review of literature and new data, 5 stages of geological-tectonic development have been identified. For the first time a systematic review of the mineral potential of the Pan-African Volta Basin was executed. Known and potentially existing mineralization have been related to the geotectonic history and metallogenetic conclusions have been drawn. Based on the findings of this research, the folded thrust belt located at the eastern rim of the Volta basin has been identified as the most prospective area for the ultramafic rocks with chromite, nickel mineralization and PGEs, hydrothermal gold and banded iron formation (BIF) but this will require further work.

Within the framework of this research, the complex geological history of the Pan African-Volta basin has been systematically reconstructed. Based on a broad review of literature and new data, 5 stages of geological-tectonic development have been identified. For the first time a systematic review of the mineral potential of the Pan-African Volta Basin was executed. Known and potentially existing mineralization have been related to the geotectonic history and metallogenetic conclusions have been drawn. Based on the findings of this research, the folded thrust belt located at the eastern rim of the Volta basin has been identified as the most prospective area for the ultramafic rocks with chromite, nickel mineralization and PGEs, hydrothermal gold and banded iron formation (BIF) but this will require further work.:Table of contents Table of contents iii List of tables v List of figures 1 Introduction 5 Summary of work done 6 Acknowledgements 6 1 In the Geology and regional geotectonic development of the West African Shield 7 1.1 Introduction 7 1.2 The basement of the Proterozoic sedimentary platform cover 9 1.3 Connection of West African Shield to Brazil 10 1.4 The Neoproterozoic sedimentary sequence and the extent of the Volta Basin 13 1.4.1 Introduction 13 1.4.2 The Neoproterozoic Sedimentary Sequence 15 1.5 The Pan-African Mobile Belt 23 1.5.1 The Buem Fold and thrust belt 23 1.5.2 New defined units 30 1.6 Interpretation of the deep structure of the Volta Basin 35 1.7 Metallic Minerals 37 1.7.1 Introduction 37 1.7.2 Iron (Fe) 39 1.7.3 Aluminium (Al) 46 1.7.4 Manganese (Mn) 50 1.7.5 Lead (Pb) 52 1.7.6 Copper (Cu) 55 1.7.7 Mineralisation related to ultramafic rocks 57 1.7.8 Gold (Au) 69 1.7.9 Tantalum (Ta) 72 1.7.10 Zirconium (Zr) 73 1.7.11 Heavy minerals in sands of Paleochannels 76 1.8 Non-metallic minerals 83 1.8.1 Introduction 83 1.8.2 Limestone (CaCO3) 84 1.8.3 Magnesite (MgCO3) 91 1.8.4 Barite (BaSO4) 93 1.8.5 Diamonds 97 1.8.6 Bitumen 100 1.9 Mineral Prediction with advangeo® Prediction Software 102 2 Minerogeny 109 2.1 Mineralisation controls and indicators 109 2.1.1 Geochemical Properties of selected stratigraphic units 109 2.1.2 Intrusive rocks 114 2.1.3 Volcanic rocks 118 2.1.4 Fault structural controls 119 2.1.5 Reactive Rocks 121 2.1.6 Other sedimentary controls: placers and paleoplacers 122 2.1.7 Laterites 122 2.1.8 Control of diamond occurrences 132 2.2 Key stages of metallogenic development 132 3 Discussion and recommendations 136 3.1 Recommendations 138 4 List of References 139 5 Appendices 144 5.1.1 Sample G113RK1 144 5.1.2 Sample G109RK1 145 5.1.3 Sample G116RK1 147 5.1.4 Sample G121RK1 149 5.1.5 Sample G121RK2 151 5.1.6 Sample G121RK3 152 5.1.7 Sample G131RK1 154 5.1.8 Sample G144RK2 155 5.1.9 Sample G145RK1 156 5.1.10 Sample G147RK1 157 5.2 Thin Sections 159 5.3 Deep drilling Data 174 5.4 Geophysical Datasets 176 5.5 Geochemical properties of volcanic rocks 181 5.6 Regional Geochemical Datasets (MSSP) 186 5.6.1 Methodology of data processing 188 5.7 Geochemical analysis – Electronic Dump 190 5.8 Geochemical properties of selected geo-tectonic units 190 5.8.1 Epicratonic basin 190 5.8.2 Foreland Basin 195 5.8.3 Thrusted continental margin 202

The advent of unoccupied aerial systems (UAS) as disruptive technology has a lasting impact on remote sensing, geophysics and most geosciences. Small, lightweight, and low-cost UAS enable researchers and surveyors to acquire earth observation data in higher spatial and spectral resolution as compared to airborne and satellite data. UAS-based applications range from rapid topographic mapping using photogrammetric techniques to hyperspectral and geophysical measurements of surface and subsurface geology. UAS surveys contribute to identifying metal deposits, monitoring of mine sites and can reveal arising environmental issues associated with mining. Further, affordable UAS technology will boost exploration data availability and expertise in the global south. This thesis investigates the application of UAS-based multi-sensor data for mineral exploration, in particular the integration of hyperspectral imagers, magnetometers and digital cameras (covering the visible red, green, blue light spectrum). UAS-based research is maturing, however the aforementioned methods are not unified effectively. RGB-based photogrammetry is used to investigate topography and surface texture. Image spectrometers measure mineral-specific surface signatures. Magnetometers detect geomagnetic field changes caused by magnetic minerals at surface and depth. The integration of such UAS sensor-based methods in this thesis augments exploration potential with non-invasive, high-resolution, safe, rapid and practical survey methods. UAS-based surveying acquired, processed and integrated data from three distinct test sites. The sites are located in Finland (Fe-Ti-V at Otanmäki; apatite at Siilinjärvi) and Greenland (Ni-Cu-PGE at Qullissat, Disko Island) and were chosen as geologically diverse areas in subarctic to arctic environments. Restricted accessibility, unfavourable atmospheric conditions, dark rocks, debris and vegetation cover and low solar illumination were common features. While the topography in Finland was moderately flat, a steep landscape challenged the Greenland field work. These restraints meant that acquisitions varied from site to site and how data was integrated and interpreted is dependent on the commodity of interest. Iron-based spectral absorption and magnetic mineral response were detected using hyperspectral and magnetic surveying in Otanmäki. Multi-sensor-based image feature detection and classification combined with magnetic forward modelling enabled seamless geologic mapping in Siilinjärvi. Detailed magnetic inversion and multispectral photogrammetry led to the construction of a comprehensive 3D model of magmatic exploration targets in Greenland. Ground truth at different intensity was employed to verify UAS-based data interpretations during all case studies. Laboratory analysis was applied when deemed necessary to acquire geologic-mineralogic validation (e.g., X-ray diffraction and optical microscopy for mineral identification to establish lithologic domains, magnetic susceptibility measurements for subsurface modelling), for example for trace amounts of magnetite in carbonatite (Siilinjärvi) and native iron occurrence in basalt (Qullissat). Technical achievements were the integration of a multicopter-based prototype fluxgate-magnetometer data from different survey altitudes with ground truth, and a feasibility study with a high-speed multispectral image system for fixed-wing UAS. The employed case studies transfer the experiences made towards general recommendations for UAS application-based multi-sensor integration. This thesis highlights the feasibility of UAS-based surveying at target scale (1–50 km2) and solidifies versatile survey approaches for multi-sensor integration. / Ziel dieser Arbeit war es, das Potenzial einer Drohnen-basierten Mineralexploration mit Multisensor-Datenintegration unter Verwendung optisch-spektroskopischer und magnetischer Methoden zu untersuchen, um u. a. übertragbare Arbeitsabläufe zu erstellen. Die untersuchte Literatur legt nahe, dass Drohnen-basierte Bildspektroskopie und magnetische Sensoren ein ausgereiftes technologisches Niveau erreichen und erhebliches Potenzial für die Anwendungsentwicklung bieten, aber es noch keine ausreichende Synergie von hyperspektralen und magnetischen Methoden gibt. Diese Arbeit umfasste drei Fallstudien, bei denen die Drohnengestützte Vermessung von geologischen Zielen in subarktischen bis arktischen Regionen angewendet wurde. Eine Kombination von Drohnen-Technologie mit RGB, Multi- und Hyperspektralkameras und Magnetometern ist vorteilhaft und schuf die Grundlage für eine integrierte Modellierung in den Fallstudien. Die Untersuchungen wurden in einem Gelände mit flacher und zerklüfteter Topografie, verdeckten Zielen und unter oft schlechten Lichtverhältnissen durchgeführt. Unter diesen Bedingungen war es das Ziel, die Anwendbarkeit von Drohnen-basierten Multisensordaten in verschiedenen Explorationsumgebungen zu bewerten. Hochauflösende Oberflächenbilder und Untergrundinformationen aus der Magnetik wurden fusioniert und gemeinsam interpretiert, dabei war eine selektive Gesteinsprobennahme und Analyse ein wesentlicher Bestandteil dieser Arbeit und für die Validierung notwendig. Für eine Eisenerzlagerstätte wurde eine einfache Ressourcenschätzung durchgeführt, indem Magnetik, bildspektroskopisch-basierte Indizes und 2D-Strukturinterpretation integriert wurden. Fotogrammetrische 3D-Modellierung, magnetisches forward-modelling und hyperspektrale Klassifizierungen wurden für eine Karbonatit-Intrusion angewendet, um einen kompletten Explorationsabschnitt zu erfassen. Eine Vektorinversion von magnetischen Daten von Disko Island, Grönland, wurden genutzt, um großräumige 3D-Modelle von undifferenzierten Erdrutschblöcken zu erstellen, sowie diese zu identifizieren und zu vermessen. Die integrierte spektrale und magnetische Kartierung in komplexen Gebieten verbesserte die Erkennungsrate und räumliche Auflösung von Erkundungszielen und reduzierte Zeit, Aufwand und benötigtes Probenmaterial für eine komplexe Interpretation. Der Prototyp einer Multispektralkamera, gebaut für eine Starrflügler-Drohne für die schnelle Vermessung, wurde entwickelt, erfolgreich getestet und zum Teil ausgewertet. Die vorgelegte Arbeit zeigt die Vorteile und Potenziale von Multisensor-Drohnen als praktisches, leichtes, sicheres, schnelles und komfortabel einsetzbares geowissenschaftliches Werkzeug, um digitale Modelle für präzise Rohstofferkundung und geologische Kartierung zu erstellen.