Petrology, Geochemistry and Petrogenesis of the Sidi El Hemissi Triassic ‘Ophites’ (Souk Ahras, NE Algeria)

  • Rabah LaouarEmail author
  • Halima Saadia Zanouda
  • Sihem Salmi-Laouar
  • Amar Sebai
  • Chrystèle Verati
  • Salah Bouhlel
  • Adrian J. Boyce
Part of the Advances in Science, Technology & Innovation book series (ASTI)


Sited in Souk-Ahras, the Sidi El Hemissi region stands as part of the Tellian Atlas, where the Triassic formation tectonically outcrops under the Tellian nappes of the Maghrebide chain. Dubbed ‘ophites’, mafic rocks, mainly gabbros and dolerites are interbedded in ~200 × 30 m lenticular body within the Triassic gypsum-rich formation. These rocks are composed of plagioclase, amphibole, pyroxene and scarce olivine crystals. Albitization represents the major alteration process, though chloritization, calcitization and epidotization of ferromagnesian minerals are also perceived. The geochemical observations prove to reveal that these mafic rocks exhibit medium- to low-Ti continental tholeiitic basalt affinity. They are enriched in LILE and LREE, as compared to HFSE and HREE, and display enriched-mid-ocean ridge basalt (E-MORB)-like incompatible element patterns in primitive mantle-normalized multi-element pattern. The weak Nb anomaly, along with the medium- to low-Ti contents, suggests possible interaction between an enriched mantle source-derived magma and lower crustal rocks. These chemical features display high similarities with those sited in the central Atlantic magmatic province (CAMP) of upper Triassic–lower Jurassic age. Hence, they turn out o be considered as highly linked to the western branch of the Alpine Tethys system, geologically and tectonically associated with the Central Atlantic Ocean opening.


Ophites Geochemistry Tholeiites Continental flood basalts Souk-Ahras 


  1. 1.
    Kurtz, J.: Geochemistry of early mesozoic basalts from Tunisia. J. Afr. Earth Sci 1(2), 113–125 (1983)Google Scholar
  2. 2.
    David, L.: Etude géologique de la haute Medjerda. Bulletin Service de la Carte Géologique de l’Algérie, 11, Algérie (1956)Google Scholar
  3. 3.
    Albarede, F.: How deep do common basaltic magmas form and differentiate? J. Geophys. Res. 97, 10997–11009 (1992)CrossRefGoogle Scholar
  4. 4.
    Floyd, P.A., Winchester, J.A.: Magma type and tectonic setting, discrimination using immobile elements. Earth Planet. Sci. Lett. 27, 211–218 (1975)CrossRefGoogle Scholar
  5. 5.
    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 Ocean Basins, vol. 42, pp. 313–345. Geological Society of London, Special Publication (1989)Google Scholar
  6. 6.
    Deckart, K., Bertrand, T.H., Liégeois, J.P.: Geochemistry and Sr, Nd, Pb isotopic composition of the Central Atlantic Magmatic Province (CAMP) in Guyana and Guinea. Lithos 82, 289–314 (2005)CrossRefGoogle Scholar
  7. 7.
    Meddah, A., Bertrand, H., Elmi, S.: La province magmatique de l’Atlantique central dans le basin des Ksour (Atlas saharien, Algérie). C.R. Geosci. 339, 24–30 (2007)CrossRefGoogle Scholar
  8. 8.
    Workman, R.K., Hart, S.R.: Major and trace element composition of the depleted MORB mantle (DMM). Earth Planet. Sci. Lett. 231, 53–72 (2005)CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Rabah Laouar
    • 1
    • 2
    Email author
  • Halima Saadia Zanouda
    • 1
  • Sihem Salmi-Laouar
    • 1
  • Amar Sebai
    • 3
  • Chrystèle Verati
    • 4
  • Salah Bouhlel
    • 5
  • Adrian J. Boyce
    • 6
  1. 1.Département de géologieUniversité Badji Mokhtar AnnabaAnnabaAlgeria
  2. 2.Laboratoire de GéodynamiqueGéologie de l’Ingénieur et Planétologie, F.S.T.G.A.T., USTHBBab EzzouarAlgeria
  3. 3.Département de Génie MinierE.N.P.El HarrachAlgeria
  4. 4.Laboratoire GéoAzurUniversité Nice-Sophia AntipolisNiceFrance
  5. 5.Mineral Resources Team, LRM2E, Geology Department, Faculty of Sciences of TunisUniversity Tunis El ManarTunisTunisia
  6. 6.Isotope Geosciences UnitSUERCEast Kilbride, GlasgowUK

Personalised recommendations