Comparison of Terrestrial Gravity and EGM 2008 Data on Extracted Lineaments: A Case Study of the Adamawa Massif, North Cameroon

Rachel Ngo Nyouma^{1, 2}, Henri Emile Pougue Eone³, Yvonne Poufone Koffi^{2, 4}, Edouard Olivier Ntomb Biboum^{2, 3,} , Alain Sterve Lepatio Tchieg^{2, 4}, Carole Bapowa Laouna¹, Willy Lemotio^{2, 4} and Patrick Mendi³

¹Ore processing Laboratory/ Institute for Geological and Mining Research, P.O. Box 4110 Yaounde, Cameroon

²University of Yaounde I, Faculty of science, Department of Physics, P.O. Box 812 Yaounde, Cameroon

³Branch for Geophysical and Volcanological Research// Institute for Geological and Mining Research, P.O. Box 370 Buea, Cameroon

⁴National Institute of Cartography, P.O. Box 157 Yaounde, Cameroon

Cite this paper:
Rachel Ngo Nyouma, Henri Emile Pougue Eone, Yvonne Poufone Koffi, Edouard Olivier Ntomb Biboum, Alain Sterve Lepatio Tchieg, Carole Bapowa Laouna, Willy Lemotio and Patrick Mendi. Comparison of Terrestrial Gravity and EGM 2008 Data on Extracted Lineaments: A Case Study of the Adamawa Massif, North Cameroon. Journal of Geosciences and Geomatics. 2021; 9(3):124-133. doi: 10.12691/jgg-9-3-3

Abstract

A structural study on the Adamawa Massif highlights the major structures (faults) of the shear zone as well as the igneous intrusion near Mayo Baleo. Through this study, a comparison on the use of gravity data from the EGM 2008 and terrestrial models was carried out on the basis of gridded gradient data obtained by applying the MAGMAP filtering algorithm on the Oasis Montaj software system. Using the gradients has an advantage in that they contain much information especially on geological structures. The resulting maxima have strong density contrasts, enabling them to be used as tools in explaining geological contacts. Gravimetric lineaments marked by the geometry of the peaks (elongated shape) and the igneous intrusion corresponding to the circular peak were detected on the horizontal gradient maps. Reconciliation with the geology, the slope map and satellite images justifies the presence of the Djohong-Ngaoundal-Dir-Tibati, Tibati-Banyo and Tignère-Banyo lineaments which indicate the underlying Foumban (extension), Tibati and Tcholliré-Banyo faults respectively, comprising the shear system residing in the massif underlain by a gneiss-migmatite bedrock. The limitation on the use of gravity data from the EGM 2008 model is manifested through the Djohong lineament correlating with the large mylonitized feature trending NE-SW, defined as a steep relief (27° to 60°), separating the Mbere basin from the upper unit with about 358 m in height difference. This terrain is a small area of relief with morphological units adapted as in the case of the mountainous areas of the West to the use of gravity data from the EGM2008. The other lineaments that are part of the shear zone fault system are not elucidated because they correspond to deep mega structures that the EGM 2008 model resolution cannot attain at depth. The use of this model is suitable for studies of superficial structures which are associated with huge formations such as the volcanic dome of Mayo Baleo, an intrusion of young trachytes with steep slopes (27° to 60°) at an altitude of 2419 m.

Keywords:
gravity horizontal gradient Bouguer anomaly lineaments

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

References:

[1]	Jean, Marcel, Abate, E. J. M., Nouck, P. Njandjock, et al. Structure of the crust beneath the South Western Cameroon, from gravity data analysis. International Journal of Geosciences, 2016, vol. 7, no 08, p. 991.
[2]	Kiamehr, R. et Gómez-Ortiz, D. A new 3D Moho depth model for Iran based on the terrestrial gravity data and EGM2008 model. In : EGU General Assembly Conference Abstracts. 2009. p. 321.
[3]	Eyike, Albert, Werner, Stephanie C., EBBING, Jörg, et al. On the use of global potential field models for regional interpretation of the West and Central African Rift System. Tectonophysics, 2010, vol. 492, no 1-4, p. 25-39.
[4]	Essi, J. M. A., Marcel, J., Atangana, J. Q. Y., Ahmad, A. D., Dassou, E. F., Mbossi, E. F., ... & Penaye, J. (2017). Interpretation of gravity data derived from the Earth Gravitational Model EGM2008 in the Center-North Cameroon: structural and mining implications. Arabian Journal of Geosciences, 10(6), 130.
[5]	Marcel, J., Essi, J. M. A., Nouck, P. N., Sanda, O., & Manguelle-Dicoum, E. (2018). Validation of gravity data from the geopotential field model for subsurface investigation of the Cameroon Volcanic Line (Western Africa). Earth, Planets and Space, 70(1), 1-18.
[6]	Marcel, C. J., Tabor, E., & Njandjock, P. (2019). Moho Discontinuity Depth Estimates for the Cameroon Volcanic Line from Gravity Data. International Journal of Economic and Environmental Geology, 17-20.
[7]	Penaye, J., Toteu, S. F., Michard, A., Bertrand, J. M., & Dautel, D. (1989). Reliques granulitiques d’âge protérozoïque inférieur dans la zone mobile panafricaine d’Afrique centrale au Cameroun; géochronologie U-Pb sur zircons. CR Acad. Sci. Paris, 309, 315-318.
[8]	Nzenti, J. P., Njanko, T., Njiosseu, E. T., & Tchoua, F. M. (1998). Les domaines granulitiques de la chaine panafricaine Nord-équatoriale au Cameroun. Geologie et environnement au Cameroun, GEOCAM, 1, 255-264.
[9]	Toteu, S. F., Deloule, E., Penaye, J., & Tchamani, R. (2004, June). Preliminary U-Pb ionic microprobe data on zircons from Poli and Lom volcano-sedimentary basins (Cameroon): Evidence for a late–Mesoproterozoic to Early Neoproterozoic (1100-950 Ma) magmatic activity in the Central African Fold Belt. In The IGCP-470 second annual field conference 5-10 January 2004, Garoua-Cameroun (abstracts) (Vol. 6).
[10]	Dumont, J. F. (1987). Etude structurale des bordures nord et sud du plateau de l'Adamaoua: influence du contexte atlantique. Géodynamique, 2(1), 55-68.
[11]	Moreau, C., Regnoult, J. M., Déruelle, B., & Robineau, B. (1987). A new tectonic model for the Cameroon Line, Central Africa. Tectonophysics, 141(4), 317-334.
[12]	Ngako, F., P. Jegouzo, and J-P. Nzenti. “Le Cisaillement Centre Camerounais. Rôle structural et géodynamique dans l'orogenèse panafricaine.” Comptes rendus de l'Académie des sciences. Série 2, Mécanique, Physique, Chimie, Sciences de l'univers, Sciences de la Terre 313.4 (1991): 457-463.
[13]	Le Marechal, A. and Vincent, P.R., 1971. Le Fossé Crétacé du Sud Adamaoua (Cameroun). Cahier d'ORSTOM Série Géologique, 3, 67-83.
[14]	Lasserre, M. (1961). Contribution à l’étude géologique de l’Afrique. Étude de la partie orientale de l’Adamaoua (Cameroun central). Bull. Dir. Min. Geol, 4, 1-131.
[15]	Gouhier, J. and Nougier, D., 1974. Contribution à l'étude volcanologique du Cameroun (“Ligne du Cameroun”-Adamaoua). Ann. Fac. Sci. Univ. Yaoundé, Yaoundé, Cameroun. 17: 3-48.
[16]	Marzoli, A., Renne, P. R., Piccirillo, E. M., Francesca, C., Bellieni, G., Melfi, A. J., ... & N'ni, J. (1999). Silicic magmas from the continental Cameroon Volcanic Line (Oku, Bambouto and Ngaoundere): 40 Ar-39 Ar dates, petrology, Sr-Nd-O isotopes and their petrogenetic significance. Contributions to Mineralogy and Petrology, 135(2-3), 133-150.
[17]	Nkouandou, O. F., Ngounouno, I., Déruelle, B., Ohnenstetter, D., Montigny, R., & Demaiffe, D. (2008). Petrology of the Mio-Pliocene volcanism to the North and East of Ngaoundéré (Adamawa, Cameroon). Comptes Rendus Geoscience, 340(1), 28-37.
[18]	Nkouandou, O. F., Ngounouno, I., & Deruelle, B. (2010). Géochimie des laves basaltiques récentes des zones Nord et Est de Ngaoundéré (Cameroun, Plateau de l’Adamaoua, Afrique centrale): pétrogenèse et nature de la source. International Journal of Biological and Chemical Sciences, 4(4).
[19]	Nono, A., Déruelle, B., Demaiffe, D., & Kambou, R. (1994). Tchabal Nganha volcano in Adamawa (Cameroon): petrology of a continental alkaline lava series. Journal of Volcanology and Geothermal Research, 60(2), 147-178.
[20]	Salviulo, G., Secco, L., Marzoli, A., Piccirillo, E. M., & Nyobe, J. B. (2000). Ca-rich pyroxene from basic and silicic volcanic rocks from the Cameroon Volcanic Line (West-Africa): crystal chemistry and petrological relationships. Mineralogy and Petrology, 70(1), 73-88.
[21]	Pavlis, N. K., Holmes, S. A., Kenyon, S. C., & Factor, J. K. (2012). The development and evaluation of the Earth Gravitational Model 2008 (EGM2008). Journal of geophysical research: solid earth, 117(B4).
[22]	Hedberg, James Dow. A geological analysis of the Cameroon trend. Princeton University, 1969.
[23]	Browne, S. E., & Fairhead, J. D. (1983). Gravity study of the Central African Rift system: A model of continental disruption: 1. The Ngaoundere and Abu Gabra Rifts. In Developments in Geotectonics (Vol. 19, pp. 187-203). Elsevier.
[24]	Nguiya, S. Investigation géophysique du bassin volcano-sédimentaire de Lom (Est-Cameroun): Implications structurale et tectonique. Thčse de Doctorat/PhD Université de Yaoundé I, 2009.
[25]	Apollinaire, B., Joseph, K., Tabod, T. C., Loudi, Y., Robert, N., Ludovic, K. H., & Valentin, O. (2017). Subsurface Structural Mapping Using Combined Terrestrial and Grace Gravity Data of the Adamawa Plateau (North-Cameroon). International Journal of Geosciences, 8(07), 869.
[26]	Gazel, J., & Gérard, G. (1954). Carte géologique de reconnaissance du cameroun au 1/500 000, feuille Batouri-Est avec notice explicative. Memoir. Direction Mines Géologie, Yaoundé, Cameroon.
[27]	Grauch, V. J. S., & Cordell, L. (1987). Limitations of determining density or magnetic boundaries from the horizontal gradient of gravity or pseudogravity data. Geophysics, 52(1), 118-121.
[28]	Phillips, J. D. (2002). Processing and Interpretation of Aeromagnetic Data for the Santa Cruz Basin--Patagonia Mountains Area, South-central Arizona. US Department of the Interior, US Geological Survey.
[29]	Blakely, R. J., & Simpson, R. W. (1986). Approximating edges of source bodies from magnetic or gravity anomalies. Geophysics, 51(7), 1494-1498.
[30]	Jacobsen, B. H. (1987). A case for upward continuation as a standard separation filter for potential-field maps. Geophysics, 52(8), 1138-1148.
[31]	De Almeida, F. F. M., & Black, R. (1967). Comparaison structurale entre le nord-est du Brésil et l'Ouest africain. In Symp. Continental Drift, Montevideo.
[32]	Ngangom, E. (1983). Etude tectonique du fossé crétacé de la Mbéré et du Djerem, Sud-Adamaona, Cameroun. Bulletin des centres de recherches exploration-Production Elf-Aquitaine, 7(1), 339-347.
[33]	François, S., 2018. Géographie physique. Presses Universitaires de France, 87:304p.
[34]	Dorbath, C., Dorbath, L., Fairhead, J. D., & Stuart, G. W. (1986). A teleseismic delay time study across the Central African Shear Zone in the Adamawa region of Cameroon, West Africa. Geophysical Journal International, 86(3), 751-766.