Nkokani Milandou Daphné Steimer Garcia1, Fori Yao Paul Assale2, Malounguila Nganga Maurice Dieudonné3, and Elenga Hilaire4
1 Geological and Mining Research Center, Republic of the Congo
2 Laboratoire de Géologie Marine et de Sédimentologie, Université Félix Houphouët-Boigny (UFHB), Abidjan, Côte d’Ivoire
3 Geological and Mining Research Center, Republic of the Congo
4 Centre de Recherches Géologiques et Minières, Brazzaville, Republic of the Congo
Original language: English
Copyright © 2026 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
A geochemical study carried out using Energy Dispersive Spectrometry (EDS) on six samples of carnallitite salts from well 3 of the Kanga permit, northwest of Pointe-Noire, confirmed the carnallitic nature of these salts. Indeed, the strong correlations between magnesium (Mg2+) and chlorine (Cl-), as well as between magnesium (Mg2+) and potassium (K+), preferentially promoted the precipitation of carnallite at the expense of bischofite. This result is related to brine homogenization and climatic aridity, which favored intense evaporation. The weak correlation observed between potassium (K+) and chlorine (Cl-) explains the absence of sylvite, as the latter acted as a catalyst in the formation of carnallite. The strong correlation between calcium (Ca2+) and sulfur (S2+) favored the formation of anhydrite beds intercalated within finely stratified halite layers of the confined phase. The strong correlation between iron (Fe3+) and silicon (Si4+), in the presence of aluminum (Al3+), led to the formation of ferriferous smectite (berthierine). The significant presence of Cl- and Na+ indicates a marine source, while Fe2+, Al3+, Si4+, Ca2+, Mg2+, K+, S2+, Ni2+, Mo2+, Mn2+, and P5+ indicate a fluvial source from rivers draining schist-limestone formations.
Author Keywords: lagoon, carnallite, smectite, Congo.
