Magnetic anomaly and lithogeochemical investigations of Cr–Ni mineralization related to the mafic-ultramafic rocks of Kettara sill, Variscan central Jebilet, Morocco

  • Abdelmajid JarniEmail author
  • El Mostafa Mouguina
  • Mohammed Jaffal
  • El Mostafa Aarab
  • Omar Guillou
  • Lhou Maacha
  • Abdelmalek Ouadjou
  • Mohamed Outhounjite
Original Paper


The hercynian Kettara sill located at the central part of the central Jebilet is known for its differentiated mafic-ultramafic rocks. In the southwest part of this massif, there is a magnetic anomaly associated with the mafic-ultramafic rocks. Susceptibility measurements indicate that these rocks are magnetic (5 to 40.1 10−3 SI). These hercynian mafic-ultramafic rocks constitute a tholeiitic series that includes voluminous plagioclase wehrlite, troctolite, olivine gabbro and leucogabbro, and thin veins of dolerite and trondhjemite. Petrographical study of these mafic-ultramafic bodies shows that the olivine, plagioclase, and clinopyroxene are commonly altered or metamorphosed to serpentine, sericite, Mg-chlorite, epidote, tremolite, and magnetite. Minor amounts of pyrrhotite, chalcopyrite, and pentlandite are present. The magmatic minerals and alteration-derived phases represent the mineralogy of Cr–Ni mineralization. Furthermore, results from inductively coupled mass spectrometry analyses show a high concentration of Cr (up to 3900 ppm) and Ni (up to 1400 ppm). The compilation of the magnetic, mineralogical, and geochemical data and their interpretation allows us to advance that (i) the magnetite, ilmenite, Cr spinel, pyrrhotite, and high content of nickel and chromium could explain the magnetic anomaly associated with the mafic-ultramafic rocks and (ii) the existence of pentlandite and Cr spinel is a strong argument that allows us to suggest that the mafic-ultramafic Kettara sill represent the host rock body of the Cr–Ni mineralization. The results of this study shed a light on the origin and the importance of some magnetic anomalies that were usually neglected by previous geophysical investigations since they are associated with the outcrops of mafic or ultramafic rocks. In that regard, this study has important implication in mineral exploration in the central Jebilet massif.


Magnetic anomaly Mafic-ultramafic Kettara sill Pentlandite and Cr spinel Cr–Ni mineralization Central Jebilets of Morocco 



This study took place in the framework of preparing a doctoral thesis in collaboration between Cadi Ayyad University and MANAGEM Group ( The authors would like to thank the “Guemassa Mining Company (CMG)” and the National Office of Hydrocarbons and Mining (ONHYM) for kindly providing the magnetic data. The authors would like to thank Prof. Larbi Rddad of the City University of New York—Kingsborough Community College—for the English editing and for constructive comments and suggestions that improve the quality of this paper. We also thank Dr. Murad Abdelruzzak Ali and Dr. Federico Lucci for their useful comments and suggestions.


  1. Aarab EM (1984) Mise en évidence du caractère cogénétique des roches magmatiques basiques et acides dans la série volcanosédimentaire de Sarhlef (Jebilet, Maroc Hercynian). Thèse de Doctorat Troisième Cycle Université Nancy I, 1–145Google Scholar
  2. Aarab EM (1995) Genèse et différentiation d’un magma tholéiitique en domaine extensif intracontinental: l’Exemple du magmatisme pré-orogénique des Jebilet (Maroc, Hercynien). Thèse de doctorat, Université Cadi Ayyad Marrakech, 1–253Google Scholar
  3. Airo M-L (2015) Geophysical signatures of mineral deposit types in Finland. Geol Surv Finland Spec Pap 58:9–70Google Scholar
  4. Allen JF, Sacr RO, Batiza R (1988) Cr-rich spinels as petrogenetic indicators: MORB-type lavas from the Lamont seamount chain, eastern Pacific. Am Mineral 73:741–753Google Scholar
  5. Arndt N-T, Fontboté L, Hedenquist J-W, Kesler S-E, Thompson John FH, Wood D-G (2017) Future global mineral resources, geochemical. Perspectives 6(1):1–184Google Scholar
  6. Ashley P, Craw D, MacKenzie D, Rombouts M, Reay A (2012) Mafic and ultramafic rocks, and platinum mineralization potential, in the Longwood Range, Southland, New Zealand. N Z J Geol Geophys 55(1):3–19. CrossRefGoogle Scholar
  7. Bajja A, Aarab EM (2009) Characterization of hercynian gabbroic complex massif of Koudiat El Khil Middle Jebilet Morocco using magnetic susceptibility variation. Research Journal of Earth Sciences 1(2):62–68 ISSN 1995–9044Google Scholar
  8. Barnes S-J, Lightfoot PC (2005) Formation of magmatic nickel sulphide ore deposits and processes affecting their copper and platinum group element contents. In Econ Geol 100 Anniversary:179–213Google Scholar
  9. Ben Aissi L (2008) Contribution à l’étude gîtologique des amas sulfurés polymétalliques de Draa Sfar et de Koudiat Aïcha : comparaison avec les gisements de Ben Sliman et de Kettara (Jebilet centrales, Maroc hercynien). Thèse de doctorat, Université Cadi Ayyad 1–353Google Scholar
  10. Bernard AJ, Maier OW, Mellal A (1988) Aperçu sur les amas sulfurés massifs des hercynides Marocaines. Mineral Deposita 23:104–114 © Springer-VerlagCrossRefGoogle Scholar
  11. Bordonaro M. (1983) Tectonique et pétrographie du district à pyrrhotine de Kettara (paléozoïque des Jebilet, Maroc). Thèse 3ème cycle, Université de Strasbourg, 1–132Google Scholar
  12. Boutroy E, Dare SAS, Beaudoin G, Barnes S-J, Lightfoot PC (2014) Magnetite composition in Ni-Cu-PGE deposits worldwide: application to mineral exploration. J Geochem Explor 145:64–81. CrossRefGoogle Scholar
  13. Causey JD, Galloway JP, Zientek ML (2009) An index to PGE-Ni-Cr deposits and occurrences in selected mineral-occurrence databases: U.S. Geological Open-File Report 2009-1045 []
  14. Clark T. (1978) Oxide minerals in the Turnagain ultramafic complex, northwestern British Columbia, Can. J. Earth Sci., 15:1893–1903Google Scholar
  15. Clark DA (1997) Magnetic petrophysics and magnetic petrology: aids to geological interpretation of magnetic surveys. AGSO Journal of Australian Geology & Geophysics 17(2):83–103 © Commonwealth of Australia 1997Google Scholar
  16. Clark DA (1999) Magnetic petrology of igneous intrusions: implication for exploration and magnetic interpretation. Explor Geophys 30:5–26CrossRefGoogle Scholar
  17. Clark DA, French DH, Lackie MA, Schmidt PW (1992) Magnetic petrology: application of integrated rock magnetic and petrological techniques to geological interpretation of magnetic surveys. Explor Geophys 23:65–68CrossRefGoogle Scholar
  18. Dare SAS, Ames DE, Lightfoot PC, Barnes S-J, Beaudoin G (2014) Mineral chemistry and supporting databases for TGI4 project on “Trace elements in Fe-oxides from fertile and barren igneous complexes: Investigating their use as a vectoring tool in the intrusions that host Ni-Cu-PGE deposits”. Geological Survey of Canada, Open File 7538. doi:
  19. El Goumi N, Jaffal M, Rolf C, Grissemann C, Melcher F, Kchikach A, Hibti M, Graupner T (2013) Rock magnetic study of basic intrusions and massive sulphides in the Hercynian central Jebilets Massif (Occidental-Meseta), Morocco. Arab J Geosci 6(2581):2597–2597. CrossRefGoogle Scholar
  20. Essaifi A (1995) Relations entre magmatisme, déformation et altération hydrothermale, l’exemple des Jebilet Centrales (Hercynien, Maroc). Mémoires Géosciences Rennes, ISSN: 1240–1498, ISBN: 2–905532–65-3, Mémoire de Géosciences – Renne N° 66 : 1–340Google Scholar
  21. Essaifi A, Hibti M (2008) The hydrothermal system of central Jebilet (Variscan Belt, Morocco): a genetic association between bimodal plutonism and massive sulphide deposits? J Afr Earth Sci 50:188–203CrossRefGoogle Scholar
  22. Essaifi A, Capdevila R, and Loui Lagard JL (1995) Transformation de Leucogabbro en chloritoschistes sous l’effet de l’altération hydrothermale et de la déformation dans l’intrusion de Kettara (Jebilet, Maroc). C R Acad Sci Paris ; t 320. Série II :189–196Google Scholar
  23. Essaifi A, Samson S, Goodenough K, (2014) Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco). Geol. Mag. Cambridge University Press, 1–26Google Scholar
  24. Haldar SK (2017) Chapter 10 - Exploration guide. In: SK Haldar (ed) Platinum-nickel-chromium deposits. Elsevier, 247–266. ISBN 9780128020418, doi
  25. Hall SR, Stewart JM (1973) The crystal structure of argentian pentlandite (Fe, Ni)8AgS8, compared with the refined structure of pentlandite (Fe, Ni)9S8. Can. Fortschr Mineral 12:169–177Google Scholar
  26. Hebert R, Laurent R (1989) Mineral chemistry of ultramafic and mafic plutonic rocks of the Appalachian ophiolites, Québec. Chem Geol 77:265–285 Elsevier Science Publishers B.V., Amsterdam -- Printed in The NetherlandsCrossRefGoogle Scholar
  27. Hibti M (2001) Les amas sulfurés des Guemassa et des Jebilet (Meseta Sud Occidentale, Maroc): Témoins de l’hydrothermalisme précoce dans le bassin mésétien. Thèse de Doctorat, Université Cadi Ayyad, Marrakech, 301 ppGoogle Scholar
  28. Huvelin P (1977) Etude géologique et gîtologique du massif hercynien des Jebilet (Maroc occidental). Note et mem. Serv. géol. Maroc, 232 bis 307pGoogle Scholar
  29. Irvine TN (1965) Chromian spinel as a petrogenetic indicator; Part 1. Theory1. Canadian journal of earth sciences. Volume 2 (1965); Canadian Contribution to the International Upper Mantle Project 73: 648–672Google Scholar
  30. Irvine TN (1975) Crystallization sequences in the Muskox intrusion and other layered intrusions - II. Origin of chromitite layers and similar deposits of other magmatic ores. Geochim Cosmochim Acta 39:991–1020CrossRefGoogle Scholar
  31. Jadid M (1989) Etude des processus de différenciation magmatique des roches préorogéniques des Jebilet Centrales sur l’exemple du massif stratiforme de Koudiat Kettara (Maroc hercynien). Thèse de 3ème cycle. Marrakech 1–215Google Scholar
  32. Jarni A, Jaffal M, Mouguina EM, Aarab EM, Maacha L, Outhounjite M, Ouadjou A, Ennaciri A, Zouhair M (2015) Contribution to the geological characterization of mafic and ultramafic rocks associated with magnetic anomalies in the central Jebilets massif (Morocco). Magmatic (Ni-Cu-Cr-PGE) mineral systems: ore forming processes and geodynamic setting; mineral resources in a sustainable world; 13th SGA Biennial Meeting 2015. Proceedings 3: 951–953; @Web of Science [v.5.23] Web of Science Core Collection Full Record; Accession Number: WOS:000374801300215; ISBN:9782855550664 ; IDS Number: BE6URGoogle Scholar
  33. Kharbouch F (1994) Les laves dévono-dinantiennes de la meseta marocaine. Etude pétro-géochimique et implications géodynamiques. Thèse de doctorat d’Etat. Univ. BrestGoogle Scholar
  34. Lightfoot PC (2007) Advances in Ni-Cu-PGE sulphide deposit models and implications for exploration technologies. In: “Proceedings of Exploration 07; Fifth Decennial International Conference on Mineral Exploration” edited by B. Milkereit 629–646Google Scholar
  35. Lightfoot and Naldrett (1984) Chemical variation of the Insizwa Complex Transkei and the nature of the parent magma. Can Mineral 22:111–123Google Scholar
  36. Maacha L, Jaffal M, Jarni A, Kchikach A, Mouguina EM, Zouhair M, Saddiqi O (2017) A contribution of airborne magnetic, gamma ray spectrometric data in understanding the structure of the central Jebilet Hercynian massif and implications for mining. J Afr Earth Sci 134:389–403. CrossRefGoogle Scholar
  37. Makeyev AB (2006) Typomorphic features of Cr-spinel and mineralogical prospecting guides for Cr ore mineralization. Russ J Earth Sci 8:ES3002. CrossRefGoogle Scholar
  38. Mateus A, Figueiras J (1999) Chemical composition of Cr-spinels in deformed and metamorphosed ultramafic/mafic complexes from Portugal; can it be used as an ore-guide for Ni-Cu sulphide mineralizations? Actas II Congresso Ibérico de Geoquímica / XI Semana de Geoquímica Lisboa, Portugal 255–258Google Scholar
  39. Mungall JE (2005) Magmatic geochemistry of the platinum-group elements. In: Mungall JE (ed) Exploration for platinum-group element deposits: Mineralogical Association of Canada Short Course Notes 35:1–34Google Scholar
  40. Mungall J.E., (2007) Magmatic ore deposits. In: Rudnick R (ed) The crust-Treatise on geochemistry 3: 1–33Google Scholar
  41. Naldrett AJ (1999) World-class Ni-Cu-PGE deposits: key factors in their genesis. Mineral Deposita 34:227–240 © Springer-VerlagCrossRefGoogle Scholar
  42. Naldrett AJ (2005) A history of our understanding of magmatic Ni–Cu sulphide deposits. Can Mineral 43:2069–2098CrossRefGoogle Scholar
  43. Naldrett AJ (2009) Secular variation of magmatic sulfide deposits and their source magmas; ©2010 Society of Economic Geologists, Inc. Econ Geol 105:669–688CrossRefGoogle Scholar
  44. ONHYM (2012) Le Nickel au Maroc. Rapport sur le Nickel au Maroc établi par l’Office National des Hydrocarbures et des Mines du Maroc (ONHYM)Google Scholar
  45. ONHYM (2015) Le Nickel au Maroc. Rapport sur le Nickel au Maroc établi par l’Office National des Hydrocarbures et des Mines du Maroc (ONHYM)Google Scholar
  46. Palache C, Berman H, Frondel C (1944) Dana’s system of mineralogy, (7th edition). I: 236–238Google Scholar
  47. Piña R, Lunar R, Ortega L, Gervilla F, Alapieti T, Martínez C (2006) Petrology and Geochemistry of Mafic-Ultramafic Fragments from the Aguablanca Ni-Cu Ore Breccia, Southwest Spain. ©2006 Society of Economic Geologists, Inc. Economic Geology, v. 101, pp. 865–881Google Scholar
  48. Rochette P (1987) Magnetic susceptibility of the rock matrix related to magnetic fabric studies. J Struct Geol 9:1015–1020CrossRefGoogle Scholar
  49. Sappin AA, Constantin M, Clark T (2006) Modèle métallogénique des principaux indices de Ni-Cu±EGP du Domaine de Port neuf-Mauricie. RP 2006–07, Ressources Naturelle et Faune, Québec, 10ppGoogle Scholar
  50. Schulz KJ, Chandler VW, Nicholson SW, Piatak N, Seall RR, Woodruff LG, and Zientek ML (2010) Magmatic sulphide-rich nickel-copper deposits related to picrite and (or) tholeiitic basalt dike-sill complexes - A preliminary deposit model: U.S. Geological Survey Open-File Report 2010–1179, 25 p. (available at
  51. Song X, Wang Y, Liemeng Chen L (2011) Magmatic Ni-Cu-(PGE) deposits in magma plumbing systems: features, formation and exploration. Geosci Front 2(3):375–384CrossRefGoogle Scholar
  52. Yamamoto H, Nissato Y (2002) Magnetic properties of Co-Ni spinel ferrite fine particles with high coercivity prepared by the chemical coprecipitation method. IEEE Trans Magn 38:3488–3492. CrossRefGoogle Scholar
  53. Youbi N, Bellon H, Marzin A, Piqué A, Cotten J, Cabanis B (2001) Du cycle orogénique hercynien au pré-rifting de l’Atlantique central au Maroc occidental: les microdiorites des Jebilet sont-elles des marqueurs magmatiques de ce passage? C. R. Acad. Sci Paris, Sciences de la Terre et des planètes / Earth and Planetary Sciences 333:295–302Google Scholar
  54. Yund RA (1962) The system Ni-As-S: phase relations and mineralogical significance. Amer J Sci 260:761–782CrossRefGoogle Scholar
  55. Zaïm Z (1990) Etude pétrographique, structurale et métamorphique de dôme thermique de Migoura (Jebilet centrales, Maroc hercynien). Thèse de 3ème cycle, Uni. Cadi Ayyad, Marrakech, Maroc, 1–148Google Scholar

Copyright information

© Saudi Society for Geosciences 2019

Authors and Affiliations

  • Abdelmajid Jarni
    • 1
    Email author
  • El Mostafa Mouguina
    • 1
  • Mohammed Jaffal
    • 2
  • El Mostafa Aarab
    • 3
  • Omar Guillou
    • 3
  • Lhou Maacha
    • 4
  • Abdelmalek Ouadjou
    • 4
  • Mohamed Outhounjite
    • 4
  1. 1.Laboratoire Dynamique de la Lithosphère et Genèse de Ressources Minérales et Energétiques, Faculté des Sciences Semlalia (Unité Associée au CNRST/ URAC 43)Université Cadi AyyadMarrakechMorocco
  2. 2.Georessources Laboratory (URAC-42); Faculty of Science and TechniqueCadi Ayyad UniversityMarrakechMorocco
  3. 3.Laboratoire de Géodynamique Magmatique, Géoressources et Géorisques, Faculté des Sciences SemlaliaUniversité Cadi AyyadMarrakechMorocco
  4. 4.Managem Group, Twin Center, ACasablancaMorocco

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