Influence of Climate and Tectonics on the Crystallization of Carnallite and Related Salts in the Congolese Atlantic Basin during the Lower Cretaceous, Republic of Congo — Oak Academic Publishing
Research ArticleOpen AccessGoogle Scholar indexed
Influence of Climate and Tectonics on the Crystallization of Carnallite and Related Salts in the Congolese Atlantic Basin during the Lower Cretaceous, Republic of Congo
Center for Geological and Mining Research, Brazzaville, Republic of Congo
,
Center for Geological and Mining Research, Brazzaville, Republic of Congo
,
Faculty of Science and Technology, Geology Course, Marien Ngouabi University, Brazzaville, Republic of Congo
,
Newco Mining SA, Pointe-Noire, Republic of Congo
1 Center for Geological and Mining Research, Brazzaville, Republic of Congo
2 Center for Geological and Mining Research, Brazzaville, Republic of Congo
3 Faculty of Science and Technology, Geology Course, Marien Ngouabi University, Brazzaville, Republic of Congo
4 Newco Mining SA, Pointe-Noire, Republic of Congo
Lithological, petrographic, and morphoscopic studies were conducted on cuttings and cores from three boreholes drilled in the Loemé salt, Kanga site, Republic of the Congo, to determine 1) the preferential conditions for crystallization of carnallite and associated salts and 2) to reconstruct paleoenvironmental and paleoclimatic conditions at the time of sedimentation. Sequential analysis of logs, sedimentary structures, carnallitite facies and associated salts concluded to the existence of a potassic carnallitite lagoon basin with low water cover, on a very wide and extensive plateau, affected by coastal waves and swells resulting from successive collapses. This basin evolved in two phases: confined and then open. The regular stratifications of halite, the rhythmicity of the halite-carnallitite elementary sequences are characteristic of salts that precipitated in relatively stable brines. These salts are therefore tectonosedimentary. The brecciated facies of the carnallitites sometimes associated with tachyhydrite result from the evolution of these deposits into salt crusts reworked by the surges into subaquatic allochemical gravelly cords under water. These crusts mark stages of partial and complete drying of the basin in a very hot and arid climate. Prolonged exposure of halite brines as well as their homogenization by surges accelerated evaporation and their abrupt evolution into carnallite brines obstructing the fossilization of sylvite. The precipitation of tachyhydrite marks the final stage of the successive complete drying of the basin.
KeywordsPotassium LagoonSurgesStable BrinesRhythmicityElementary SequencesSalt CrustsArid ClimateRepublic of the Congo
Chumakov, N.M., Zharkov, M.A., Herman, A.B., Doludenko, M.P., Kalandadze, N.N., Lebedev, E.L., Ponomarenko, A.G. and Rautian, A.S. (1995) Climatic Belts of the Mid-Cretaceous Time. Stratigraphy and Geological Correlation, 3, 241-260.
Anne-Claire, C. (2012). Impact of Climate and Tectonics on the Dynamics of Sedimentary Systems during the Opening of the South Atlantic. University of Rennes, Rennes, 260 p.
Moulin, M., Aslanian, D. and Unternehr, P. (2010) A New Starting Point for the South and Equatorial Atlantic Ocean. Earth Science Reviews, 98, 1-37. https://doi.org/10.1016/j.earscirev.2009.08.001
Davison, I. (2007) Geology and Tectonics of the South Atlantic Brazilian Salt Basins. In: Ries, A.C., Butler, R.W.H. and Graham, R.H., Eds., Deformation of the Continental Crust: The Legacy of Mike Coward, Vol. 272, Geological Society of London, London, 345-359. https://doi.org/10.1144/GSL.SP.2007.272.01.18
Dorling, S., Elliot, J. and Scogings, A. (2011). Technical Report on Sintoukola Potash Project. Elemental Minerals Limited, Projet Republic of Congo. http://www.SEDAR.com
Dorling, S., Rigby, N. and O’Hara, P. (2012) NI43-101 Technical Report Sintoukola Potash Project Republic of Congo. Elemental Minerals Limited, West Perth Western Australia, 315 p.
Warren, J.K. (2006) Evaporites: Sediments, Resources and Hydrocarbons. Springer, Berlin, 1036 p. https://doi.org/10.1007/3-540-32344-9
De Ruiter, P.A.C. (1979) The Gabon and Congo Basins Salt Deposits. The Bulletin of the Society Economic Geologists, 74, 419-431. https://doi.org/10.2113/gsecongeo.74.2.419
Feuga, B., Schlund, J.M. and Wasmer, B. (2005) The Flooding of the Holle Potash Mine (Republic of Congo). Proceedings of the Solution Mining Research Institute Fall, Nancy, 1-5 October 2005, 1-19.
Desthieux, F., Boudzoumou, F., Malounguila Nganga, D., Diakubuka, E., Mouanda, Moumpossa, F., Ondongo, C., Ongouya, A., Akiaoue, E., Missamou, A., Malera, M., Kiba, V. and Nzaba, M. (1993). Explanatory Note of the Geological Map of the Republic of Congo at 1/1,000,000. Ministry of Mines and Energy, General Directorate of Mines, 27 p.
Baudouy, S. and Legorjus, C. (1991), Sendji Field—People’s Republic of Congo, Congo Basin. In: Foster, N.H. and Beaumont, E.A., Eds., Treatise of Petroleum Geology, Atlas of Oil and Gas Fields—Structural Traps V, American Association of Petroleum Geologists, Tulsa, 121-149.
Harris, N.B. (2000) Toca Carbonate, Congo Basin: Response to an Evolving Rift Lake. In: Mello, M.R. and Katz, B.J., Eds., Petroleum Systems of South Atlantic Margins, American Association of Petroleum Geologists, Tulsa, 341-360. https://doi.org/10.1306/M73705C24
Belmonte, Y., Hirtz, P. and Wenger, R. (1965) The Salt Basins of the Gabon and the Congo (Brazzaville); A Tentative Palaeogeographic Interpretation. In: Ion, D.C., Ed., Salt Basins around Africa, The Institute of Petroleum, London, 55-74.
Lambert, R. (1967) Geological Sketches of the Congolese Potassic Basin. Annals of Mines, 11, 709-723.
Brownfield, M.E. and Charpentier, R.R. (2006). Geology and Total Petroleum Systems of the West-Central Coastal Province (7203), West Africa. In: U.S. Geological Survey Bulletin 2207-B, U.S. Department of the Interior, Washington DC, 52 p.
Chamley, H. (2011) Basics of Sedimentology. 2nd Edition, Dunod, Paris, 234 p.
Karner, G.D., Driscoll, N.W., McGinnis, J.P., Brumbaugh, W.D. and Cameron, N.R. (1997) Tectonic Significance of Syn-Rift Sediment Packages across the Gabon-Cabinda Continental Margin. Marine and Petroleum Geology, 14, 973-1000. https://doi.org/10.1016/S0264-8172(97)00040-8
Moulin, M. (2003) Geological and Geophysical Study of Passive Continental Margins: Example of Zaire and Angola. Ph.D. Thesis, University of Western Brittany, Brest.
Moulin, M., Aslanian, D., Olivet, J.-L., Contrucci, I., Matias, L., Géli, L., Klingelhoeffer, F., Nouzé, H., Réhault, J.-P. and Unternehr, P. (2005) Geological Constraints on the Evolution of the Angolan Margin Based on Reflection and Refraction Seismic Data (ZaiAngo Project). Geophysical Journal International, 162, 793-810. https://doi.org/10.1111/j.1365-246X.2005.02668.x
Van den Belt, F.J.G. and de Boer, P.L. (2007) A Shallow Basin Model for ‘Saline Giants’ Based on Isostasy-Driven Subsidence. In: Nichols, G., Williams, E. and Paola, C., Eds., Sedimentary Processes, Environments and Basins: A Tribute to Peter Friend, Special Publication Number 38 of the International Association of Sedimentologists, Vol. 38, 241-252. https://doi.org/10.1002/9781444304411.ch11
Souza-Lima, W. (2008) Sequencia evaporitica da bacia de Sergipe-Alagoas. In: Mohriak, W.U., Szatmari, P. and Couto Anjos, S., Eds., Sal: Geologia e Tectonica, Edicoes Beca, Petrobras, Sao Paulo, 231-249.
Davison, I., Anderson, L. and Nuttall, P. (2012) Salt Deposition, Loading and Gravity Drainage in the Campos and Santos Salt Basins. In: Alsop, G.I., Archer, S.G., Hartley, A.J., Grant, N.T. and Hodgkinson, R., Eds., Salt Tectonics, Sediments and Prospectivity, Vol. 363, Geological Society of London, London, 159-174. https://doi.org/10.1144/SP363.8
Freitas, J.T.R. (2006) Ciclos deposicionais evaporíticos da bacia de santos: A cicloestratigráfica analysis from dados de 2 pocos e de tracos de sísmica. Universidade Federal do Rio Grande do Sul, Farroupilha, 168 p.
Montaron, B. and Tapponier, P. (2010) A Quantitative Model for Salt Deposition in Actively Spreading Basins. American Association of Petroleum Geologists, Search and Discovery, Article No. 30117.
Wardlaw, N.C. (1972) Unusual Marine Evaporites with Salts of Calcium and Magnesium Chloride in Cretaceous basins of Sergipe, Brazil. Economic Geology, 67, 156-168. https://doi.org/10.2113/gsecongeo.67.2.156
Wardlaw, N.C. and Nicholls, G.D. (1972) Cretaceous Evaporites of Brazil and West Africa and Their Bearing on the Theory of Continent Separation. 24th International Geological 1392 Congress, Montréal, 43-55.
Meister, E.M. and Aurich, N. (1972) Geologic Outline and Oil Fields of Sergipe Basin, Brazil. American Association of Petroleum Geologists Bulletin, 56, 1034-1047. https://doi.org/10.1306/819A40AC-16C5-11D7-8645000102C1865D
Teisserenc, P. and Villemin, J. (1989) Sedimentary Basin of Gabon—Geology and Oil Systems. In: Edwards, J.D. and Santogrossi, P.A., Eds., Divergent/Passive Margin Basins, Volume 46, American Association of Petroleum Geologists Memoir, 117-199. https://doi.org/10.1306/M48508C3
Pasley, M.A., Wilson, E.N., Abreu, V.A., Brandao, M.G.P. and Telles, A.S. (1998) Lower Cretaceous Stratigraphy and Source Rock Distribution in Pre-Salt Basins of the South Atlantic—Comparison of Angola and Southern Brazil. American Association of Petroleum Geologists Bulletin, 82, 1949.
Pasley, M.A., Wilson, E.N., Abreu, V.A., Brandao, M.G.P. and Telles, A.S. (1998) Lower Cretaceous Stratigraphy and Source Rock Distribution in Pre-Salt Basins of the South Atlantic—Comparison of Angola and southern Brazil. In: Mello, M.R. and Yilmaz, P.O., Eds., Rio ’98—Petroleum Geology in a Changing World, Rio de Janeiro, 8-11 November 1998, 822-823.
Uncini, G., Brandao, M.G.P. and Giovannelli, A. (1998) Neocomian-Upper Aptian Pre-Salt Sequence of Southern Kwanza Basin—A Regional View. American Association of Petroleum Geologists Bulletin, 82, 1894-1895.
Podder, J., Gao, S., Evitts, R.W., Besant, R.W. and Matthews, W. (2013). Crystallization of Carnallite from KCl-MgCl2 Brine Solutions by Solvent Evaporation Process and Its Structural and Mechanical Characterization. Journal of Metals, Materials and Minerals, 23, 37-41.
Pannach, M., Paschke, I., Schmidt, H., Freyer, D. and Voigt, W. (2020) Crystallization of Metastable Monoclinic Carnallite, KCl⋅MgCl2⋅6H2O: Missing Structural Link in the Carnallite Family. Acta Crystallographica Section C: Structural Chemistry, 76, 507-512. https://doi.org/10.1107/S2053229620005197