Xenoliths enclosed in Lavas of the Nyos volcano (Cameroon Volcanic Line, continental sector) range from fertile lherzolites to harzburgites. One spinel-free wehrlite has been also sampled. The occurrence of phlogopites and pargasites in some harzburgites together with specific textural rock-type (lherzolites transitional porphyroclastic to equigranular), including major and trace element compositions both in peridotites bulk rocks and minerals point out interactions between the mantle and basaltic magmas responsible for the formation of wehrlites beneath the Nyos volcano. Hydrous minerals (phlogopites and pargasites) and metasomatic events are their main petrogeochemical signatures different from group 1 samples which are characterized by spoon-shaped REE patterns. Later on, hydrous phases, Ti-rich Cpx, CaO rich Ol, Ti, and V rich Ol wehrlite precipitated from melt enrichments due to the percolation of the mantle by basaltic magmas of alkaline affinity. The metasomatic liquid which percolates the Nyos mantle column was a dense alkaline silicate rich in volatile, displaying low HFSE abundances in the metasomatic hydrous melts compared to the LILE. It is suggested that Nyos mantle peridotites have experienced: 1) variable metasomatic events related to the percolating of the depleted mantle by a alkaline silicate liquid, 2) the spinel-free wehrlite is a group 2 sample corresponding to a cumulate of a similar melt, 3) amphibole may be a potassium-bearing mineral instead of or in addition to phlogopite at shallower levels of Nyos upper mantle and 4) transitional textural rock facies express also the fingerprint of rising mantle plume which were percolated by alkaline magma during their transit to the surface.
Moreau, C., Regnoult, T.M., Déruelle, B. and Robineau, B. (1987) A New Tectonic Model for Cameroon Line, Central Africa. Tectonophysics, 139, 317-334. https://doi.org/10.1016/0040-1951(87)90206-X
Déruelle, B., Moreau, C., Nkoumbou, C., Kambou, R., Lissom, J., Njonfang, E., Ghogomu, R.T. and Nono, A. (1991) The Cameroon Line: A Review. In: Kampunzu, A.B. and Lubala, R.T., Eds., Magmatism in Extensional Structure Setting, Springer-Verlag, Heidelberg, 274-328. https://doi.org/10.1007/978-3-642-73966-8_12
Meyers, J.B., Rosendahl, B.R., Harrison, C.G.A. and Zan-Dong, D. (1998) Deep-Imaging Seismic and Gravity Results from the Offshore Cameroon Volcanic Line, and Speculation of African Hotlines. Tectonophysics, 284, 31-63. https://doi.org/10.1016/S0040-1951(97)00173-X
Teitchou, M.I. (2008) Volcanologie, pétrologie et géochimie comparées de quelques plaines continentales (Kumba, Tombel, Noun, Nyos) de la Ligne du Cameroun. Ph.D Thesis, University of Yaoundé I, Yaoundé, 206 p.
Temdjim, R., Boivin, P., Chazot, G., Robin, C. and Rouleau, E. (2004) L’hétérogénéité du manteau supérieur à l’aplomb du volcan de Nyos (Cameroun) révélée par les enclaves ultrabasiques. Comptes Rendus Geoscience, 336, 1239-1244. https://doi.org/10.1016/j.crte.2004.07.005
Nana, R. (2001) Pétrologie des péridotites en enclaves dans les basaltes alcalins récents de Nyos: Apport à la connaissance du manteau supérieur de la Ligne du Cameroun. Thèse doctorat d’Etat Université Yaoundé I, Yaoundé, 250 p.
Aka, F.T., Nagao, K., Kusakabe, M. and Ntepe, N. (2009) Cosmogenic Helium and Neon in Ultramafic Xenoliths from the Cameroon Volcanic Line (West Africa): Preliminary Observations. Journal of African Earth Sciences, 55, 175-184. https://doi.org/10.1016/j.jafrearsci.2009.04.002
Aka, FT, Hasegawa, T., Nche, L.A., Asobo, N.E.A., Mimba, M.E., Teitchou, I., Ngwa, C.N., Miyabuchi, Y., Kobayashi, T., Kankeu, B., Yokoyama, T., Tanyileke, G., Ohba, T., Hell, J.V. and Kusakabe, M. (2018) Upper Triassic Mafic Dykes of Lake Nyos, Cameroon (West Africa) I: K-Ar Age Evidence within the Context of Cameroon Line Magmatism, and the Tectonic Significance. Journal of African Earth Sciences, 141, 49-59. https://doi.org/10.1016/j.jafrearsci.2018.02.001
Marzoli, A., Picirillio, E.M., Renne, P.R., Bellieni, G., Iacumin, M., Nyobe, J.B. and Tongwa, A.F. (2000) The Cameroon Volcanic Line Revisited: Petrogenesis of Continental Basaltic Magmas from Lithospheric and Asthenospheric Mantle Sources. Journal of Petrology, 41, 87-109. https://doi.org/10.1093/petrology/41.1.87
Teitchou, M.I., Grégoire, M., Dantas, C. and Tchoua, F.M. (2007) Le manteau supérieur à l’aplomb de la plaine de Kumba (ligne du Cameroun), d’après les enclaves de péridotites à spinelles dans les laves basaltiques. Comptes Rendus Geoscience, 339, 101-109. https://doi.org/10.1016/j.crte.2006.12.006
Teitchou, M.I., Grégoire, M., Temdjim, R., Ghogomu, R.T., Ngwa, C. and Aka, F.T. (2011) Mineralogical and Geochemical Fingerprints of Mantle Metasomatism beneath Nyos Volcano (Cameroon Volcanic Line). In: Beccaluva, L., Bianchini, G. and Wilson, M., Eds., Volcanism and Evolution of the African Lithosphere, Geological Society of America Boulder, Special Paper 478, 193-210. https://doi.org/10.1130/2011.2478(10)
Streckeisen, A. (1976) To Each Plutonic Rock Its Proper Name. Earth-Science Reviews, 12, 1-33. https://doi.org/10.1016/0012-8252(76)90052-0
Boivin, P. (1982) Interactions Entre Magmas Basaltiques et Manteau Supérieur. Arguments apportés par les enclaves basiques des basaltes alcalins. Exemples de Devès (Massif Central Francais) et du volcanisme quaternaire Carthagène (Espagne). Thèse d’état, Université de Clermont II, 344 p.
Neumann, E.R. and Wulff-Pederson, E. (1997) The Origin of Highly Silicic Melts in the Mantle Xenoliths from the Canary Islands. Journal of Petrology, 38, 1513-1539. https://doi.org/10.1093/petroj/38.11.1513
Grégoire, M., Moine, B.N., O’Reilly, S.Y.., Cottin, J.Y. and Giret, A. (2000) Trace Element Residence and Partitioning in Mantle Xenoliths Metasomatized by Highly Alcaline, Silicate and Carbonate Rich Melts (Kerguelen Islands, Indian Ocean). Journal of Petrology, 41, 477-509. https://doi.org/10.1093/petrology/41.4.477
Remaidi, M. (1993) Etude pétrologique et géochimique d’une association de péridotites réfractaires-pyroxénites dans le massif de Ronda (Espagne). Implications pour les mécanismes de circulation des magmas dans le manteau supérieur. Thèse Université de Montpellier, Montpellier, 360 p.
Pouchou, J.L. and Pichoir, F. (1984) A New Model for Quantitative X-Ray Micro-Analysis: Part I. Application to the Analysis of Homogeneous Samples. Recherche Aérospatiale, 5, 13-38.
Dantas, C., Ceuleneer, G., Grégoire, M., Python, M., Freydier, R., Warren, J. and Dick, H.B.J. (2007) Pyroxenites Dredged along the South-West Indian Ridge, 9°-16°E: Cumulates from Incremental Melt Fractions Produced at the Top of a Cold Melting Regime. Journal of Petrology, 48, 647-660. https://doi.org/10.1093/petrology/egl076
Bonati, E. and Michael, J. (1989) Mantle Peridotite from Continental Rifts to Ocean Basin to Subduction Zones. Earth and Planet Science Letters, 91, 297-311. https://doi.org/10.1016/0012-821X(89)90005-8
Tamura, A. and Arai, S. (2006) Harzburgite-Dunite-Orthopyroxenite Suite as Record of Supra-Subduction Zone Setting for the Oman Ophiolite Mantle. Lithos, 90, 43-56. https://doi.org/10.1016/j.lithos.2005.12.012
Nixon, P.H. (1987) Mantle Xenoliths. John Wiley and Sons, Chichester, 844 p.
Caldeira, R. and Munhá, J.M. (2002) Petrology of Ultramafic Nodules from Sao Tomé Island, Cameroon Volcanic Line (Oceanic Sector). Journal of African Earth Sciences, 34, 231-246. https://doi.org/10.1016/S0899-5362(02)00022-2
Tamen, J. (1998) Contribution à l’étude géologique du plateau Kapsiki (Extrême-Nord, Cameroun): Volcanologie, pétrologie et géochimie. Thèse 3ème cycle Univrsité Yaoundé I, Yaoundé, 127 p.
Princivalle, F., Salviulo, G., Marzoli, A. and Picccirillo, E.M. (2000) Clinopyroxene of Spinel-Peridotite Xenoliths from Lake Nji (Cameroon Volcanic Line, W Africa): Crystal Chemistry and Petrological Implications. Contributions to Mineralogy Petrology, 139, 503-508. https://doi.org/10.1007/s004100000151
Menzies, M.A. and Hawkesworth, C.J. (1987) Mantle Metasomatism. Academic Press, London, 472 p.
Clague, D.A. (1988) Petrology of Ultramafic Xenoliths from Loihi Seamount, Hawai. Journal of Petrology, 29, 1161-1186. https://doi.org/10.1093/petrology/29.6.1161
Girod, M., Dautria, J.-M., Ball E. and Soba D. (1984) Estimation de la profondeur du Moho, sous le massif volcanique de l’Adamaoua (Cameroun), à partir de l’étude d’enclaves de lherzolite. Comptes Rendus Geoscience, 298, 699-704.
Leake, B.E. (1978) Nomenclatures of Amphiboles. The American Mineralogist, 63, 1023-1052.
Zerka, M. (2004) Le manteau sous la marge Maghrébine: Relations infiltrations-réactions-cristallisations et cisaillements lithosphériques dans les enclaves ultramafiques du volcanisme alcalin plio-quaternaire d’Oranie, exemple des complexes d’Ain-Temouchent et de la Basse Tafna (Algérie nord-occidentale). Thèse Doctorat d’Etat, Université Oran, Oran, 345 p.
Fabriès, J., Bodinier, J.L., Dupuy, C., Lorand, J.P. and Benkerrou, C. (1989) Evidence for Modal Metasomatism in the Orogenic Spinel Lherzolite Body from Caussou (Northeastern Pyrénées, France). Journal of Petrology, 30, 199-228. https://doi.org/10.1093/petrology/30.1.199
Zerka, M, Cottin, J.Y., Grégoire, M., Lorand, J.P., Mergartsi, M. and Midoum, M. (2002) Les xénolites ultramafiques du volcanisme alcalin quaternaire d’Oranie (Tell, Algérie Occidentale), témoins d’une lithosphère cisaillée et amincie. Comptes Rendus Geoscience, 334, 387-394. https://doi.org/10.1016/S1631-0713(02)01771-6
McDonough, W.F. and Sun, S.-S. (1995) The Composition of the Earth. Chemical Geology, 120, 223-253. https://doi.org/10.1016/0009-2541(94)00140-4
Weber, B. (1991) Interactions basalte-lithosphère mantellique en contexte intraplaque océanique: Exemple du tahiti et Tahaa (plaque rigide) et de la Réunion (plaque lente). Thèse d’Université, Ecole des Mines de Paris, Paris, 222 p.
Jagoutz, E., Palme, H., Baddenhauser, H., Blum, K.,Cendales, M., Dreibus, G., Spettel, B., Lorenz, V. and Wanke, H. (1979) The Abundance of Major, Minor and Trace Elements in the Earth’s as Derived from Primitive Ultramafic Nodules. Proceedings 10th Lunar and Planetary Science Conference, Texas, 2031-2050.
McDonough, W.F. and Frey, F.A. (1989) Rare Earth Elements in Upper Mantle Rocks. In: Geochemistry and Mineralogy of Rare Earth Elements, Review in Mineralogy, Vol. 21, Mineralogical Society of America Publ., London, 99-139. https://doi.org/10.1515/9781501509032-008
Siena, F., Beccaluva, L., Colcorti, M., Marchesi, S. and Morra, V. (1991) Ridge to Hot Spot Evolution of the Atlantic Lithosphere Mantle: Evidence from Lanzarote Peridotite Xenoliths (Canary Islands). Journal of Petrology, 271-290. https://doi.org/10.1093/petrology/Special_Volume.2.271
Sun, S.S. and McDonough, W.F. (1989) Chemical and Isotopic Systematics of Oceanic Basalts: Implications for the Mantle Composition and Processes. In: Saunders, A.D. and Norry M.J., Eds., Magmatism in the Oceanic Basin, Geological Society, London, Special Publications, Blackwell Scientific Publications, Oxford, 313-346. https://doi.org/10.1144/GSL.SP.1989.042.01.19
Girardeau, J. and Francheteau, J. (1993) Plagioclase-Wehrlites and Peridotites on the East Pacific Ridge (Hess Dufi) and the Mid Atlantic Ridge (DSPP Sole, 33W): Evidence for Magma Percolation in the Oceanic Upper Mantle. Earth and Planetary Science Letters, 115, 137-149. https://doi.org/10.1016/0012-821X(93)90218-X
Menzies, M.A., Arculus, R.J., Best, M.G., Bergman, S.C., Ehrenberg, S.N., Irving, A.J., Roden, M.F. and Schule, D.J. (1987) A Record of Subduction Processes and Within-Plate Volcanism of the Southern USA. In: Nixon, P.H., Ed., Mantle Xenoliths, John Wiley Sons, Chichester, 41-58.
Bodinier, J.-L., Vasseur, G., Vernières, J., Dupuy, C. and Fabriès, J. (1990) Mechanism of Mantle Metasomatism: Geochemical Evidence from the Lherz Orogenic Peridotite. Journal of Petrology, 31, 597-628. https://doi.org/10.1093/petrology/31.3.597
Berger, E.T. and Vannier, M. (1984) Les dunites en enclaves dans les basaltes des iles océaniques: Approche pétrologique. Bulletin of Mineralogy, 107, 649-663. https://doi.org/10.3406/bulmi.1984.7809
Bodinier, J.-L. (1988) Geochemistry and Petrogenesis of the Lanzo Peridotite Body, Western Alps. Tectonophysics, 149, 67-88. https://doi.org/10.1016/0040-1951(88)90119-9
Touret, J., Gregoire, M. and Teitchou, M.I. (2010) Was the Letal Eruptrion of Lake Nyos Relted to Double CO2/H2O Density Inversion? Comptes Rendus Geosciences, 341, 19-26. https://doi.org/10.1016/j.crte.2009.10.005
Navon, O. and Stopler, E. (1987) Geochemical Consequences of Melt Percolation: the Upper Mantle as a Chromatographic Column. Journal of Geology, 95, 285-307. https://doi.org/10.1086/629131
Ionov, D.A., Bodinier, J.-L., Mukasa, S.B. and Zanetti, A. (2002) Mechanism and Sources of Mantle Metasomatism: Major and Trace Element Compositions of Peridotites Xenoliths from Spitsbergen in the Context of Numerical Modelling. Journal of Petrology, 43, 2219-2259. https://doi.org/10.1093/petrology/43.12.2219
Ionov, D.A., Chazot, G., Chauvel, C., Merlet, C. and Bodinier, J.L. (2006) Trace Elements in Peridotite Xenoliths from Tok, SE Siberian Craton: A Record of Pervasive, Multi-Stage Metasomatism in Shallow Refractory Mantle. Geochimica et Cosmochimica Acta, 70, 1231-1260. https://doi.org/10.1016/j.gca.2005.11.010
Girardeau, J. and Mercier, J-C. (1988) Petrology and Texture of the Ultramafic Rocks of the Ngaze Ophiolite (Tibet). Constraints for Mantle Structure beneath Slow-Spreading Ridges. Tectonophysics, 47, 35-58. https://doi.org/10.1016/0040-1951(88)90146-1
Menzies, M.A. (1983) Mantle Ultramafic Xenoliths in Alkaline Magma: Evidence for Heterogeneity Modified by Magmatic Activity. In: Hawkesworth, C.J. and Norry, M.J., Eds., Continental Basalts and Mantle Xenolith, Shiva Publ., Nantwich, 92-110.
Moine, B.N., Grégoire, M., O’Reilly, S., Sheppard, S.M.F. and Cottin, J.Y. (2001). High Field Strength Element (HFSE) Fractionation in the Upper Mantle: Evidence from Amphibole-Rich Composite Mantle from the Kerguelen Islands (Indian Ocean). Journal of Petrology, 42, 2145-2167. https://doi.org/10.1093/petrology/42.11.2145
Colcorti, M., Beccaluva, L., Bonadiman, C., Salvini, L. and Siena, F. (2000) Glasses in Mantle Xenolith as Geochemical Indicators of Metasomatic Agents. Earth and Planetary Science Letters, 183, 303-320. https://doi.org/10.1016/S0012-821X(00)00274-0
Grégoire, M., Lorand, J.P., Cottin, J.Y., Giret, A., Mattielli, N. and Weiss, D. (1997) Xenoliths Evidence for a Refractory Oceanic Mantle Percolated by Basaltic Melts beneath the Kerguelen Archipelago. European Journal of Mineralogy, 9, 1085-1100. https://doi.org/10.1127/ejm/9/5/1085
Bjerg, E.A., Ntaflos, T., Kurat, G., Dobosi, G. and Labudia, C.H. (2005) The Upper Mantle beneath Patagonia, Argentina, Documented by Xenoliths from Alkali Basalts. Journal of South American Earth sciences, 18, 125-145. https://doi.org/10.1016/j.jsames.2004.09.002
Neumann, E.R. (1991) Ultramafic and Mafic Xenoliths from Hiero, Canary Islands: Evidence for Melt Percolation in the Upper Mantle. Contributions to Mineralogy and Petrology, 106, 236-252. https://doi.org/10.1007/BF00306436
Kalfoum, F., Ionov, D. and Merlet, C. (2002) HFSE Residence and Nb-Ta Ratios in Metasomatised, Rutile Bearing Mantle Peridotites. Earth and Planetary Science Letters, 199, 49-65. https://doi.org/10.1016/S0012-821X(02)00555-1
Eggler, D.H. (1987) Enrichment Processes and Basaltic Volcanism. In: Menzies, M.A. and Hawkesworth, C.J., Eds., Mantle Metasomatism, Academic Press, London, 21-39.
Luguet, A., Alard, O., Lorand, J.P., Perason, N.J., Ryau, C. and O’Reilly, S. (2001) Laser-Ablation Microprobe (LAM-ICPMS) Unravels the Highly Siderophile Element Geochemistry of Oceanic Upper Mantle. Earth and Planetary Science Letters, 189, 285-294. https://doi.org/10.1016/S0012-821X(01)00357-0
Klamadji, M.N., Dedzo, M.G., Tchameni, R. and Dawai, D. (2020) Petrography and Geochemical Characterization of Dolerites from Figuil (Northern Cameroon) and Léré (Southwestern Chad). International Journal of Geosciences, 11, 459-482. https://doi.org/10.4236/ijg.2020.117023
Moundi, A., Ménard, J.-J., Reusser, E., Tchoua, F.M. and Dietrich, V.J. (1996) Découverte de basaltes transitionnels dans le secteur continental de la Ligne du Cameroun (Massif du Mbam, Ouest-Cameroun). Comptes Redus Academie. Sciences. Paris, 322, 831-837.
Fosso, J., Ménard, J.-J., Bardintzeff, J.-M., Wandji, P., Tchoua, F.M. and Bellon, H. (2005) Les laves du mont Bangou: Une première manifestation volcanique éocène, à affinité transitionnelle, de la Ligne du Cameroun. Comptes Rendus Geosciences, 337, 315-325. https://doi.org/10.1016/j.crte.2004.10.014
Kuepouo, G., Tchouankoue, J.P., Nagao, T. and Sato, H. (2006). Transitional Tholeiitic Basalts in the Tertiary Bana Volcano-Plutonic Complex, Cameroon Line. Journal of African Earth Sciences, 45, 318-332. https://doi.org/10.1016/j.jafrearsci.2006.03.005
Moundi, A., Wandji, P., Bardintzeff, J.-M., Ménard, J.-J., Okomo Atouba, L.C., Mouncherou, O.F. and Tchoua, F.M. (2007) Les basaltes éocènes à affinité transitionnelle du plateau Bamoun, témoins d’un réservoir mantellique enrichi sous la ligne volcanique du Cameroun. Comptes Rendus Geoscience, 339, 396-406. https://doi.org/10.1016/j.crte.2007.04.001
Kagou Dongmo, A., Wandji, P., Poucle, A., Vicat, J.-P., Cheilletz, A., Nkouathio, D.G., Alexandrov, P. and Tchoua, F.M. (2001) Evolution volcanologique du mont Manengouba (Ligne du Cameroun): Nouvelles données pétrographiques, géochimiques et géochronologiques. Comptes Rendus Géosciences, 333, 155-162. https://doi.org/10.1016/S1251-8050(01)01625-1
Ngongang, N., Wagsong, M., Owono, F., Badriyo, I., Essomba, P., Tchikankou, N., Youmen, D., Kamgang, P. and Chazot, G. (2021) Mineralogy and Magmatic Processes of Cenozoic Intraplate Alkaline Volcanic Rocks of Bafang and Its Environs (Cameroon Volcanic Line, West Africa). Open Journal of Geology, 11, 210-238. https://doi.org/10.4236/ojg.2021.116013
Chazot, G., Menzies, M.A. and Harte, B. (1996) Determination of Partition Coefficients between Apatite, Clinopyroxene, Amphibole and Melt in Natural Spinel Lherzolites from Yemen: Implication for Wet Melting of the Lithospheric Mantle. Geochimica et Cosmochimica Acta, 60, 423-437. https://doi.org/10.1016/0016-7037(95)00412-2
Darwson, J.B. (1984) Constrasting Types of Upper Mantle Metsomatism. In: Kornprobst, J., Ed., Kimberlites II. The Mntle Crust Relationship, Elsevier, Amsterdam, 289-294. https://doi.org/10.1016/B978-0-444-42274-3.50030-5
Patkó, L., Liptai, N., Aradi, L.E., Klébesz, R., Sendula, E., Bodnar, R.J. and Szabó, C. (2019) Metasomatism-Induced Wehrlite Formation in the Upper Mantle beneath the Nógrád-Gomor Volcanic Field (Northern Pannonian Basin): Evidence from Xenoliths. Geoscience Frontiers, 11, 943-964. https://doi.org/10.1016/j.gsf.2019.09.012