Experimental Abrasion Study of the Evolution of Gold Morphological Criteria in Different Sediments as a Function of Time
- 1 Institute of Earth Sciences, Faculty of Sciences and Techniques, Cheikh Anta Diop University of Dakar, Dakar, Senegal
Abstract
The use of gold as a tracer element for understanding the mode of emplacement of these formations requires a good knowledge of its dynamics. To this end, we have carried out experimental studies to investigate the evolution of contour states (regular, irregular), surface states (blunt, rough), shape (elongation) and dimension (size). The study of these criteria is carried out on SEM photos of particles, taken before and after the experiment, using Aphelion image processing software. Five experiments were carried out to study the influence of sediment granulometry and water dilution on particle morphological changes. The results of these experiments show that coarse sediments (>1 mm) are largely responsible for morphological changes in gold. They cause fragmentation and/or folding of the particle edges, depending on the magnitude of the impact forces. Strong impacts due to high water dilution cause staking on the particle surface. Fine sediments (<1 mm) slow down particle evolution as they cushion impacts and particles tend to flatten rather than fragment.
- Edou-Minko, A. (1988) Pétrologie et géochimie des latérites à “stone lines” du gite d’or d’Ovala. Application à la prospection en zone équatoriale humide (Gabon). Thèse, Université de Poitiers, Poitiers, 147 p.
- Colin, F., Sanfo, Z., Brown, E., Bourlés, D. and Edou Minko, A. (1997) Gold: A Tracer of the Dynamics of Tropical Laterites. Geology, 25, 81-84. https://doi.org/10.1130/0091-7613(1997)025 2.3.CO;2
- Parisot, J.C., Ventose, V., Gradin, G., Bourges, F., Debat, P., Tollon, F. and Millo, L. (1995) Dynamique de l’or et d’autres minéraux lourds dans un profil d’altération cuirassé du Burkina Fasso, Afrique de l’Ouest. Intéret pour l’interprétation dans la mise en place des matériaux constituant les cuirasses de haut glacis. Géosciences de Surface, Comptes Rendus de l’Académie des Sciences, Paris.
- Bamba, O., Parisot, J.C., Grandin, G. and Beauvais, A. (2002) Ferricrite Genesis and Supergene Gold Behaviour in Burkina Faso, West Africa. Geochemistry: Exploration, Environnement, Analysis, 2, 3-14. https://doi.org/10.1144/1467-787302-001
- Ouangrawa, M., Grandin, G., Parisot, J.C. and Delaune, M. (2000) Evolution des particules d’or en milieu latéritique Soudano-Sahelien: alluvion et colluvion dans l’environnement d’un gite filonien, Piéla, Burkina Fasso. Bulletin de la Société Géologique de France, 171, 395-405. https://doi.org/10.2113/171.4.397
- Diome, F. (2012) L’or, traceur de la mise en place des formations superficielles, au Sénégal oriental. Thèse d’Etat en Géologie, Faculté des Sciences et Techniques de l’UCAD, Dakar, 200 p.
- Colin, F. (1992) L’or traceur de l’histoire chimique de l’altérosphère latéritique sous foret. In: Sédimentologie et Géochimie de la surface: à la mémoire de Georges Millot, 111-155.
- Herail, G. (1990) Morpholocal and Chimical Evolution of Gold Grains during the Formation of a Polygenique Fluviatile Placer: The Moi-Pliocene Tipuani placer example (Andes, Bolivie). Chronique de la Recherche Minière, N°500, 41-49.
- Yeend, W.E. (1975) Experimental Abrasion of Detrital Gold. Journal of Research of the U.S. Geological Survey, 3, 203-212.