Magnetic trace and modeling of the alkaline-carbonatitic magmatism in the Quilengues region, SW Angola
DOI:
https://doi.org/10.21701/bolgeomin/136.1/004Keywords:
SW Angola, Mesozoic magmatism, Alkaline-Carbonatite magmas, Magnetic anomalies, 3D ModelingAbstract
In the SW Angola, during the Mesozoic and in a context of intracontinental extension, the rise of plutonic to volcanic bodies of tholeiitic, alkaline, carbonatite and kimberlitic composition took place. The Tchivira and Bonga massifs exhibit the evolutionary sequence between different alkaline and carbonatite pulses that are reflected in the associated magnetic anomalies. Tchivira has the highest composition across the range of high magnetic susceptibility alkaline to ultra-alkaline materials within a complex alkaline to tholeiitic dike swarm extending in a NNE-SSW direction. Bonga is mainly carbonatite with an absence of ferromagnetic materials. The 3D inversion of the Tchivira magnetic field strength data shows the geometry at depth of three plutonic bodies generating the anomalies. The 3D model obtained, without any other previously available information (boreholes, samples etc.), thus contributes to the knowledge of the geometry of the intrusion of carbonatite bodies and alkaline-carbonatite complexes in extensional contexts. Additionally, Bouguer anomaly provides some information about the cortical structure in the area. The carbonatitic bodies are associated with magnetic anomalies of lower intensity (between -50 and +200 nT, in Tchivira and between -150 and -50 nT, in Bonga) than the syenite and gabbro bodies. The possible presence of carbonatite bodies at depths between 400 and 2000 m increases their potential for exploration for Light Rare Earth-bearing minerals, as well as other critical elements of interest.
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Instituto Geológico y Minero de España
Grant numbers 15903
