Skip Navigation Links.
Journal of Geosciences and Geomatics. 2021, 9(4), 160-176
DOI: 10.12691/JGG-9-4-1
Original Research

Petrological and Geochemical Characteristics of the Cretaceous Ngaou Boh Anorogenic Complex (Adamawa Plateau, Cameroon Line): Preliminary Constraints

Zénon Itiga1, , Benoît Joseph Mbassa2, Rose Noël Ngo Belnoun3, Pierre Wotchoko4, Dieudonné Tchokona Seuwui5, Sébastien Owona1, Jacques-Marie Bardintzeff6, Pierre Wandji5 and Hervé Bellon7

1Department of Earth Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon

2Institute for Geological and Mining Research, Laboratory of Ore mineral Processing, P.O. Box 4110, Yaoundé, Cameroon

3Department of Earth Sciences, University of Yaoundé, P.O. Box 812, Yaoundé, Cameroon

4Higher Teacher Training College, University of Bamenda I, P.O. Box 39, Yaoundé, Cameroon

5Higher Teacher Training College, University of Yaoundé I, P.O. Box 47, Yaoundé, Cameroon

6Université Paris-Saclay, Sciences de la Terre, Volcanologie, Planétologie, UMR CNRS, 8148 GEOPS, bât 504, F-91405, Orsay, France

7Université européenne de Bretagne, CNRS UMR, 6538 Domaines océaniques, UBO-IUEM, 6 avenue Le Gorgeu, CS 93837, F-29238, Brest cedex 3, France

Pub. Date: September 07, 2021
Full Text PDF

Cite this paper

Zénon Itiga, Benoît Joseph Mbassa, Rose Noël Ngo Belnoun, Pierre Wotchoko, Dieudonné Tchokona Seuwui, Sébastien Owona, Jacques-Marie Bardintzeff, Pierre Wandji and Hervé Bellon. Petrological and Geochemical Characteristics of the Cretaceous Ngaou Boh Anorogenic Complex (Adamawa Plateau, Cameroon Line): Preliminary Constraints. Journal of Geosciences and Geomatics. 2021; 9(4):160-176. doi: 10.12691/JGG-9-4-1

Abstract

The Cretaceous Ngaou Boh anorogenic complex (NBAC) located in the far North Adamawa Plateau, the centre domain of the Cameroon Line constitutes a plutonic-volcanic ring association. The whole rock K-Ar datation yields a crystallization age of ca. 74 Ma. Plutonic rocks comprise abundant alkali feldspar granites, scarce clinopyroxene-amphibole gabbros and alkali feldspar syenites. Alkali feldspar granites are leucocratic, coarse to fine-grained; quartz and K-feldspars are the major rock-forming mineral, besides minor oligoclase, biotite and accessory phases as sphene, zircon and opaques. Alkali feldspar syenites are mesocratic coarse-grained, mainly composed of K-feldspars with small amounts of quartz and biotite. Volcanic rocks consist of a basanite-trachyte-rhyolite suite. Basanites contain olivine and diopside phenocrysts and a groundmass essentially composed of plagioclase and titanomagnetite. Biotite-clinopyroxene trachytes and clinopyroxene-amphibole rhyolites have an almost homogeneous modal composition, mainly made up of sanidine and anorthoclase microliths, scarce phenocrysts of quartz, and minor crystals of biotite, clinopyroxene (augite) amphibole (pargasite, sandagaite); Fe-Ti oxides (ilmenite, titanomagnetite) and fibreglass are often isolated in the groundmass. Plutonic rocks are alkaline, weakly metaluminous with some alkali feldspar granites displaying agpaitic or peralkaline feature. Incompatible Trace elements (HFSE and LILE) distribution and chondrite-normalized REE patterns evidence a significant petrogenetic link between clinopyroxene-amphibole gabbros, alkali feldspar syenites and alkali feldspar granites. All the analysed samples are enriched in incompatible elements, indicating melts from spinel and garnet-bearing mantle source close to OIB component. Indeed, the (Tb/Yb)N ratios of both basanites (2.3-2.5) and clinopyroxene-amphibole gabbros (1.4-1.9) suggest different parental magma sources. Alkali feldspar granites appear as residue of magma differentiation led by crystal fractionation of liquid derived from the partial melting of spinel peridotite mantle. Clinopyroxene-amphibole rhyolites and biotite-clinopyroxene trachytes (Mg#=0.0-15.4) derive through fractional crystallization from basanites (Mg#=64.3-60.1), the most primitive mafic parental melt. Both plutonic rocks and lavas trends evidence a bimodality highlighted by a pronounced “Daly gap”.

Keywords

Ngaou Boh, Cameroon Line, Adamawa Plateau, anorogenic complex, magma differentiation, K/Ar age dating

Copyright

Creative CommonsThis 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]  Nkono, C., Féménias, O., Demaiffe, D., “Geodynamic model for the development of the Cameroon Hot Line (Equatorial Africa)”, Journal of African Earth Sciences, 100, 626-633, 2014.
 
[2]  Déruelle, B., Ngounouno, I., Demaiffe, D., “The ‘‘Cameroon Hot Line” (CHL): a unique example of active alkaline intraplate structure in both oceanic and continental lithospheres”, Comptes Rendus Geosciences, 339, 589-600, 2007.
 
[3]  Nkouathio, D.G., Kagou Dongmo, A., Bardintzeff, J.M., Wandji, P., Bellon, H., Pouclet, A., “Evolution of volcanism in graben and horst structures along the Cenozoic Cameroon Line (Africa): implications for tectonic evolution and mantle source composition”, Mineralogy and Petrology, 94, 3-4, 287-303, 2008.
 
[4]  Njonfang, E., Nono, A., Kamgang, P., Ngako, V., Tchoua M.F., “Cameroon Line magmatism (central Africa): a reappraisal”, in Beccaluva, L., Bianchini, G., Wilson, M. (Eds.), Volcanism and Evolution of the African Lithosphere: Geological Society of America Special Paper, vol. 478. The Geological Society of America, Inc., 173-191, 2011.
 
[5]  Lasserre, M., “Mise au point sur les granitoïdes dits “ultimes” du Cameroun: gisement, pétrographie et géochronologie”, Bull. B.R.G.M., 2è série, IV, n°2, 143-159, 1978.
 
[6]  Jacquemin, H., Sheppard, S.M.F., Vidal, P., “Isotopic geochemistry (O, Sr, Pb) of the Golda Zuelva and Mboutou anorogenic complexes, North Cameroon: mantle origin with evidence of crustal contamination”, Earth and Planetary Science Letters, 61, 97-111, 1982.
 
[7]  Ghogomu, R.T., Moreau, C., Brown, W.L., Rocci, G., “The Ntumbaw complex, NW Cameroon: an atypical anorogenic ring complex of intermediate composition”, Journal of African Earth Sciences, 8, 1-9, 1989.
 
[8]  Kambou, R., Nzenti, J.P., Soba, D., “Apport à la connaissance des complexes anorogéniques d’âge tertiaire de la Ligne du Cameroun: le complexe pluto-volcanique de Tchégui (Nord-Cameroun)”, Comptes Rendus de l’Académie des Sciences, 308, 1257-1260, 1989.
 
[9]  Njonfang, E., Moreau, C., “The mineralogy and geochemistry of a subvolcanic alkaline complex from the Cameroon Line: The Nda Ali massif, southwest Cameroon”, Journal of African Earth Sciences, 22, 2, 113-132, 1996.
 
[10]  Njonfang, E., Tchuenté Tchoneng, G., Cozzupoli, D., Lucci, F., “Petrogenesis of the Sabongari alkaline complex, Cameroon line (central Africa): Preliminary petrological and geochemical constraints”, Journal of African Earth Sciences, 83, 25-54, 2013.
 
[11]  Njonfang, E., Laurenzi, M.A., Wokwenmendam Nguet, P., Cozzupoli, D., “40Ar-39Ar ages from the Sabongari and Nana igneous complexes within the central part of the Cameroon Line (Central Africa)”, Journal of African Earth Sciences, 147, 20-27, 2018.
 
[12]  Ngounouno, I., Moreau, C., Déruelle, B., Demaiffe, D., Montigny, R., “Pétrologie du complexe alcalin sous-saturé de Kokoumi (Cameroun)”, Bulletin de la Société Géologique de France, 172, 675-686, 2001.
 
[13]  Njonfang, E., Moreau, C., “The mafic mineralogy of the Pandé massif, Tikar plain, Cameroon: implications for a peralkaline affinity and emplacement from highly evolved alkaline magma”, Mineralogical Magazine, 64, 525-537, 2000.
 
[14]  Kamdem, J.B, Kraml, M., Keller, J., Henjes-Kunst-F, “Cameroon Line magmatism: conventional K/Ar and single-crystal laser 40Ar/39Ar ages of rocks and minerals from the Hosséré Nigo anorogenic complex, Cameroon”, Journal of African Earth Sciences 35 (1): 99-105, 2002.
 
[15]  Ngonge, E.D., Hollanda, M.H.B.M., Nsifa Nkonguin, E., Tchoua, M.F., “Petrology of the Guenfalabo ring-complex: An example of complete series along the Cameroon Volcanic Line (CVL), Cameroon”, Journal of African Earth Sciences, 96, 139-154, 2014.
 
[16]  Itiga, Z., Chakam Tagheu, P.J., Wotchoko, P., Wandji, P., Bardintzeff, J.M., Bellon, H., “La ligne du Cameroun: Volcanologie et géochronologie de trois régions (mont Manengouba, plaine du Noun et Tchabal Gangdaba)”, Géochronique, 91, 13-16+ p. 3 couv., 2004.
 
[17]  Itiga, Z., Bardintzeff, J.M., Wotchoko, P., Wandji, P., Bellon, H., “Tchabal Gangdaba massif in the Cameroon Volcanic Line: a bimodal association”, Arabian Journal of Geosciences, 7, 11: 4641-4664, 2014.
 
[18]  Itiga, Z., Bonin, B., Bardintzeff, J.M., Wandji, P., Ngo Belnoun, R.N., Mbassa, B.J., Wotchoko, P., Tchokona Seuwui, D., Ntepe Nfomou,. Bellon, H., “The Pan-African post-collision Hosséré Mana plutonic complex and associated Gapi Stock (Western Cameroon Domain, Cameroon): Petrology, mineralogy and geochemistry”, Journal of African Earth Sciences, 149, 398-425, 2019.
 
[19]  Toteu, S.F., Penaye, J., Poudjom Djomani, Y., “Geodynamic evolution of the Pan-African belt in central Africa with special reference to Cameroon”, Canadian Journal of Earth Sciences, 41, 73-85, 2004.
 
[20]  Bellon, H., Rangin, C., “Geochemistry and isotopic dating of Cenozoic volcanic arc sequences around the Celebes and Sulu Seas”, Proceedings of the Ocean Drilling Program: Scientific Results, 124, 1991.
 
[21]  Steiger, R.H., Jäger, E., “Subcommission on geochronology: Convention on the use of decay constants in geo-and cosmochronology”, Earth and Planetary Science Letters, 36, 356-362, 1977.
 
[22]  Mahood, G.A., Drake, R.E., “K-Ar dating young rhyolitic rocks: a case study of Sierra la Primavera, Mexico”, Geological Society American Bulletin, 93, 1232-1241, 1982.
 
[23]  Morimoto, N., Fabries, J., Ferguson, A.K., Ginzburg, I.V., Ross, M., Seifert, F.A., Zussman, J., Aoki, K., Gottardi, G., “Nomenclature of pyroxenes”, Mineralogical Magazine, 52, 535-550, 1988.
 
[24]  Hawthorne, F.C., Oberti, R., Harlow, G.E., Maresch, W.V., Martin, R.F., Schumacher, J.C., Welch, M.D., “Nomenclature of the amphibole supergroup”, American Mineralogist, 97, 11-12, 2031-2048, 2012.
 
[25]  Le Maitre, R.W. (Ed), “Igneous Rocks, a Classification and glossary of terms. (Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks)” Cambridge University Press, Cambridge, UK, 2002.
 
[26]  Miyashiro, A., “Nature of alkalic volcanic rocks series”, Contributions to Mineralagy and Petrology, 66, 91-104, 1978.
 
[27]  Shand, S.J., “Eruptive Rocks. Their Genesis, Composition, Classification, and Their Relations to Ore-deposits”, Wiley, New York, 444 pp., 1943.
 
[28]  Maniar, P.D., Piccoli, P.M., “Tectonic discrimination of granitoids”, Geological Society and of America Bulletin, 101, p. 635-643, 1989.
 
[29]  Chappell, B.W., White, A.J.R., “Two contrasting granite types”. Pac. Geol. 8, 173-174, 1974.
 
[30]  Frost, B.R., Arculus, R.J., Barnes, C.G., Collins, W.J., Ellis, D.J., Frost, C.D., “A geochemical classification of granitic rocks”, Journal of Petrology, 42, 2033-2048, 2001.
 
[31]  McDonough, W.F., Sun, S.S., “The composition of the Earth”, Chemical Geology, 120, 223-253, 1995.
 
[32]  Rudnick, R.L., Gao, S., “Composition of the Continental Crust. “Treatise on Geochemistry”, Elsevier (Ed.), 3, 1-64, 2003.
 
[33]  Sun, S.S., McDonough, W.F., “Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes”, In: Saunders, A.D., Norry, M.J. (Eds.), Magmatism in the Ocean Basins, vol. 42. Geological Society Special Publication, 313-345, 1989.
 
[34]  Pearce, J.A., Harris, N.J., Tindle, A., “Trace element discrimination diagrams for the geotectonic interpretation of granite rocks”, Journal of Petrology, 15, 956-983, 1984.
 
[35]  Eby, G.N., “Chemical subdivision of A-type granitoids: petrogenetic and tectonic implications”, Geology, 20, 641-644, 1992.
 
[36]  Bonin, B., “A-type granites and related rocks: evolution of a concept, problems and prospects”, Lithos, 97, 1-29, 2007.
 
[37]  Thiéblemont, D., Tegyey, M., “Une discrimination géochimique des roches différenciées témoin de la diversité d’origine et de situation tectonique des magmas calco-alcalins”, Comptes Rendus Acad. Sci. Paris, Ser. II, 319, 87-94, 1994.
 
[38]  Gorton, M.P., Schandl, E.S., “From continents to island arcs: a geochemicalindex of tectonic setting for arc-related and within-plate felsic to intermediate volcanic rocks”, Canadian Mineralogist, 38, 1065-1073, 2000.
 
[39]  Schandl, E.S., Gorton, M.P., “Application of high field strength elements to discriminate tectonic settings in VMS environments”, Economic Geology, 97,629-642, 2002.
 
[40]  Pearce, J.A., “Trace element characteristics of lavas from destructive plate boundaries”, In: Thorpe, R.S. (Ed.), Andesites: Orogenic Andesites and Related Rocks. John Wiley, Chichester, pp. 525–548, 1982.
 
[41]  Pearce, J.A., “Role of the sub-continental lithosphere in magma genesis at active continental margins”, In: Hawkesworth, C.J., Norry, M.J. (Eds.), Continental Basalts and Mantle Xenoliths. Shiva, Nantwich, 230-249, 1983.
 
[42]  Coish, R.A., Sinton, C.W, “Geochemistry of mafic dikes in the Adirondac mountains: implications for the constitution of Late Precambrian mantle”, Contributions to Mineralogy and Petrology, 110, 500-514, 1992.
 
[43]  Green, T.H., “Significance of Nb/Ta as an indicator of geochemical processes in the crust mantle system”, Chemical Geology, v. 120, 347-359, 1995.
 
[44]  Wang, K., Plank, T., Walker, J.D., Smith, E.I., A mantle melting profile across the Basin and Range, SW USA”, Journal of Geophysical Research, 107, B1-21, 2002.
 
[45]  Barbarin, B., “A review of relationships between granitoids types, their origins and their geodynamic environments”, Lithos, 46, 605-626, 1999.
 
[46]  Chappel, B.W., “Aluminium saturation in I- and S-type granites and the characterization of the fractionated haplogranites”, Lithos, 46, 535-551, 1999.
 
[47]  Mbassa, B.J., Kamgang, P., Grégoire, M., Njonfang, E., Benoit, M., Itiga, Z., Duchene, S., Bessong, M., Wokwenmendam Nguet, P., Ntepe Nfomou, “Evidence of heterogeneous crustal origin for the Pan-African Mbengwi granitoids and the associated mafic intrusions (North western Cameroon, central Africa)”, Comptes Rendus Géoscience, 348, 116-126, 2016.
 
[48]  Anderson, J.L., Morrison J., “Ilmenite, magnetite and peraluminous Mesoproterozoic anorogenic granites of Laurentia and Baltica”, Lithos, 80, 45-60, 2005.
 
[49]  Joron, J.L., Cabanis, B., Treuil, M., “Méthodes d’identification des séries anciennes basées sur la géochimie des éléments en traces”, Centre Recherches Exploration-Production Elf Aquitaine, 7, 1, 273-284, 1983.
 
[50]  Cox, K.G., Bell, J.D., Pankhurst, R.J., “The interpretation of igneous rocks”, George, Allen and Unwin, London, Boston, Sydney, 1979.
 
[51]  Daly, R.A., “The geology of Ascension Island”, Proc. Am. Acad. Arts Sci., 60, 1-80, 1925.
 
[52]  Watson, E.B., Harrison, T.M., “Zircon saturation revisited: temperature and composition effects in a variety of crustal magma types”, Earth and Planetary Science Letters, 64 (2), 295-304, 1983.
 
[53]  Harrison, T.M., Watson, E.B., “The behavior of apatite during crustal anatexis: equilibrium and kinetic considerations”. Geochemica Cosmochimica Acta, 48 (7), 1467-1477, 1984.
 
[54]  Andersen, D.J., Lindsley, D.H., “New and final model for the Ti-magnetite/ilmenite geothermometer and oxygen barometer”, Abstract AGU 1985. Spring meeting Eos. Transaction American Geophysical Union, 66 (18), 416, 1985.
 
[55]  Lepage, L.D., “ILMAT: an excel worksheet for ilmenite-magnetite geobarometry and geobarometry”, Computers and Geosciences, 29 (5) 673-678, 2003.