Genesis and classification of soils developed on gabbro in the high reliefs of Maroua region, North Cameroon

Abstract

The purpose of this work was to examine the genesis, properties and classification of soils resulting from the weathering of gabbro rock in the high reliefs of Maroua in the Far North Region of Cameroon. The studied soils were ~ 2 m thick, made of four horizons which consisted of coarse saprolite, fine saprolite, loose loamy clayey horizon and humiferous horizon. From petrographical view point, at the bottom of the soil profile, the preservation of the bedrock structure was marked by numerous remnants of altered plagioclases shapes. The groundmass was characterized by a double spaced fine, ranging to equal, enaulic c/f related distribution pattern. It was yellowish, characterized by weakly separated granular microstructure in the fine saprolite and had a speckled and cloudy limpidity in the loose loamy clayey horizon. Secondary minerals consisted of montmorilonite, kaolinite, goethite, quartz, gibbsite, lepidocrocite, sepiolite, feldspar and calcite. Globally, Si/Al ratio ranged between 2.85 and 3.24. The chemical index of alteration ranged from 50.95 to 55.27 % while the mineralogical index of alteration values were between 1.90 and 10.54 %. Physicochemically, soil pH varied from slightly acidic to slightly above neutral. Soil organic carbon contents were low to very low. Exchangeable bases contents were high, mostly represented by Ca2+ and Mg2+. The CEC of soils and the CEC of clay were also high, ranging respectively between 53.68 and 82.88 cmol(+).kg-1, and 116.80 and 181.38 cmol(+).kg-1. The studied soils were classified as dystric haplustepts clayey isohyperthermic. They were developed in situ by the collapse of primary mineral structures from the bottom of the coarse saprolite, due to leaching as a result of bisiallitisation and monosiallitisation. This is accompanied by a progressive ferruginization of materials, confirmed by the densification under the microscope of goethitic brown veil from the base to the loamy clay horizon and the increase in iron contents from the bedrock to the humiferous surface horizon. 

Keywords

• Genesis,classification,soils,gabbro,Maroua,Cameroon

References

1. Amouric, M., Olives, J., 1998. Transformation mechanisms and interstratifications in conversion of smectite to kaolinite: an HRTEM study. Clays and Clay Minerals 46(5): 521-527.
2. Badía, D., Martí, C., Aznar, J. M., León, J., 2013. Influence of slope and parent rock on soil genesis and classifcation in semiarid mountainous environments. Geoderma 193-194: 13-21.
3. Bai, Y.Y., 2009. Distribution of Soil Temperature Regimes and Climate Change in the Mojave Desert Region. PhD Thesis. University of California Riverside, 137 p.
4. Bockheim, J.G., Gennadiyev, A.N., Hammer, R.D., Tandarich, J.P., 2005. Historical development of key concepts in pedology. Geoderma 124: 23-36.
5. Bray, R.H., Kurtz, L.T., 1945. Determination of total organic and available forms of phosphorus in soils. Soil Science 59 : 22-229.
6. Costantini, E.A.C., Priori, S., 2007. Pedogenesis of plinthite during early Pliocene in the Mediterranean environment. Case study of a buried paleosol at Podere Renieri, central Italy. Catena 71: 425-443.
7. De Martonne, E., 1926. Aréisme et Indice d’Aridité. Comptes Rendus Académie des Sciences 181: 1395-1398.
8. Dengiz, O. Sağlam, M., Özaytekin, H.H, Baskan, O., 2013. Weathering rates and some physico-chemical characteristics of soils developed on a calcic toposequences. Carpathian Journal of Earth and Environmental Sciences 8(2): 13-24.

9. Driessen, P., Deckers, J., Spaargaren, O., Nachtergaele, F., 2001. Lecture notes on the major soils of the world. Word Soil Resources Reports, 94. FAO, Rome, 334 p.
10. Gracheva, R., 2011. Formation of soil diversity in themountainous tropics and subtropics: rocks, time and erosion. Geomorphology 135: 224-231.
11. Herrmann, L., Anongrak, N., Zarei, M., Schuler, U., Spohrer, K., 2007. Factors and processes of gibbsite formation in Northern Thailand. Catena 71: 279-91.
12. Irfan, T.Y., 1996. Mineralogy, fabric properties and classification of weathered granites in Hong Kong. Quaterly Journal of Engineering Geology and Hydrogeology 29(1): 5-35.
13. Jones, B.F., Galán, E., 1988. Sepiolite and palygorskite. In: Bailey, S.W. (Ed.), Hydrous Phyllosilicates (Exclusive of Micas). Reviews in Mineralogy, vol. 19. Mineralogical Society of America, Washington, DC, pp. 631-674.
14. Lal, R., Stewart, B.A., 1990. Soil Degradation. New York, Springel-Verlag, 362 p.
15. Meunier A., 2003. Les argiles. Collection Géosciences, GB Science Publisher, 433p.
16. Nahon, D., 1991. Introduction to the Petrology of Soils and Chemical Weathering. John Wiley, New York, 313p.
17. Nesbitt, H.W., Young, G.M., 1982. Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature 279: 715-717.
18. Ngounou Ngatcha, B., Mudry, J., Sigha Nkamdjou, L., Njitchoua, R., Naah, E., 2005. Climate variability and impacts on an alluvial aquifer in a semi-arid climate, the Logone-Chari plain (South of Lake Chad). International Association of Hydrological Sciences 295: 94-100.
19. Nguetnkam, J.P., Kamga, R., Villiéras, F., Ekodeck, G.E., Yvon, J., 2008. Variable weathering response of granite in tropical zones. Example of two sequences studied in Cameroon (Central Africa). Comptes Rendus Geoscience 340(7) : 451-461.
20. Ozaytekin, H.H., Uzun, C., 2012. Comparison of weathering rates of the soils classified in Alfisol and Entisol order developed on limestone in the Taurus Mountains at East Mediterranean region. Carpathian journal of Earth and Environmental Sciences 7(1): 109-120.
21. Paquet, H., Clauer, N., 1997. Soils and sediments, Mineralogy and geochemistry, Springer-Verlag, Berlin, Heidelberg, 369 p.
22. Pédro, G., 1966. Essai sur la caractérisation géochimique des différents processus zonaux résultant de l’altération des roches superficielles (cycle alumino-silicique). Comptes Rendus de l'Académie des Sciences Série D 262: 1828-1831.
23. Pedro, G., 1982. The conditions of formation of secondary constituents. In: Bonneau M. and Souchier B. (eds), Constituents and properties of soils. Academic Press, London, pp. 63-81.
24. Pimentel, D., 1993. Word Soil Erosion and Conservation, Cambrdge, UK, Cambridge University Press, 349 p.
25. Pimentel, D., 2006. Soil erosion: a food and environmental threat, Environmental, Development and Sustainnability 8: 119-137.
26. Pimentel, D., Harvey, C., Resosudarmo, P., Sinclair, K., Kurz, D., McNair, M., Crist, S., Shpritz, L., Fitton, L., Saffouri, R., Blair, R., 1995. Environmental and economic costs of soil erosion and conservation benefits. Science 267: 1117-1123.
27. Pimentel, D., Kounang, N., 1998. Ecology of soil erosion in ecosystems. Ecosystem 1: 416-426.
28. Singer, A., 1979. Palygorskite in sediments: detrital, diagenetic or neoformed. A critical review. Geologische Rundschau 68: 996-1008.
29. Singer, A., 1984. Pedogenic palygorskite in the arid environment. In: Singer, A., Galán, E. (Ed.), Palygorskite-Sepiolite. Occurrences, Genesis and Uses. Developments in Sedimentology 37. Elsevier, Amsterdam, pp. 169-177.
30. Soil Survey Staff , 2010. Keys to Soil Taxonomy. United States Department of Agriculture, Natural Resources Conservation Service, Eleventh Edition, 338p.
31. Stoops, G., 2003. Guidelines for analysis and description of soil and regolith thin sections. Soil Society of America, INC., Madison, USA, 184p.
32. Tsozué, D., Bitom, D., Yongue-Fouateu, R., 2011. In Situ genesis of alumino ferruginous nodules in a soil profile developed on garnet rich micaschist in the high reliefs of South Cameroon Rainforest Zone (Central Africa). The Open Geology Journal 5: 56-66.
33. Tsozué, D., Haiwe, B. R., Louleo, J., Nghonda, J.P., 2014. Local initiatives of land rehabilitation in the Sudano-Sahelian region: Case of Hardé soils in the far North Region of Cameroon. Open Journal of Soil Science 4: 6-16.
34. Tsozué, D., Nghonda, J. P., Mekem, D.L., 2015. Impact of land management system on crop yields and soil fertility in Cameroon. Solid Earth 6: 1087-1101.
35. Tunçay, T., Dengiz, O., 2016. Chemical weathering rates and geochemical-mineralogical characteristics of soils developed on heterogeneous parent material and toposequence. Carpathian Journal o Earth and Environmental Sciences 11(2): 583-598.
36. USDA, 2004. Soil survey laboratory methods manual, Soil survey investigation report no. 42, Version 4.0. USDA-NCRS, Lincoln, NE, 700p.
37. Velde, B., 1995. Origin and mineralogy of clays. Clays and the environment. Springer-Verlag, New York, 334p.
38. Voicu, G., Bardoux, M., Jébrak, M., Voicu, D., 1996. Normative mineralogical calculations for tropical weathering profiles. Geological Association of Canada and Mineral Association of Canadian Program with Abstract 21: A-69.
39. Walkley, A., Black, I.A., 1934. Determination of organic matter in soil. Soil Science 37: 549-556.