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Geologische Rundschau

, Volume 85, Issue 4, pp 619–631 | Cite as

Inception and demise of a Neoproterozoic ocean basin: evidence from the Ougda complex, western Hoggar (Algeria)

  • J. Dostal
  • R. Caby
  • C. Dupuy
  • C. Mevel
  • J. V. Owen
Original Paper

Abstract

The Neoproterozoic Ougda magmatic complex occurs within platformal carbonate rocks in the western part of the Pan-African fold belt of the Tuareg shield (NW Africa). It is composed of - 800 Ma old, relatively high P-T (i.e., Grt + Cpx-bearing: P > 5 kbar; T≈900'Q, tholeiitic mafic/ultramafic cumulates and related rocks intruded by intermediate to mafic calcalkali plutons (e.g., Cpx+Hbl-bearing gabbro) and dikes. Apparent contrasts in structural level of crystallization indicate that the calc-alkali rocks are significantly younger than the tholeiites, which temporally correlate with a period of regional extension in this part of Africa. Intrusion of the calc-alkali rocks may have occurred during the formation of an arc after the tholeiitic rocks had been (diapirically?) emplaced within the shelf carbonates, and prior to (> 630 Ma) the Pan-African orogeny. Data reported herein indicate that the Ougda complex records the inception and demise of a Neoproterozoic ocean basin. Similar crustal sections have been described from collisional (e.g., Aleutian islands) and extensional (e.g., Ivreä-Verbano zone) settings, indicating that processes operating in both environments can generate nearly indistinguishable igneous suites; the prevalence of shallow-level calc-alkali rocks in both settings may mask the presence of more mafic, tholeiitic rocks at depth.

Key words

Pan-African tectonics geochemistry crustal extension island arc tholeIIte calc-alkali gabbro 

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References

  1. Arculus RJ, Wills KJA (1980) Petrology of plutonic blocks and inclusions from the Lesser Antilles island arc. J Petrol 21:743–799CrossRefGoogle Scholar
  2. Bayer R, Lesquer A (1978) Les anomalies gravimetriques de la bordure orientale du craton ouest-africain: geometrie d'une suture pan-africaine. Bull Soc Geol France 6:863–876CrossRefGoogle Scholar
  3. Bertrand-Sarfati J, Moussine-Pouchkine A, Caby R (1987) Les corrélations du Protérozoïque au Cambrien en Afrique de l'Ouest: nouvelle interpretation géodynamique. Bull Soc Géol France 8:855–865Google Scholar
  4. Black R, Latouche L, Liégeois JP, Caby R, Bertrand JM (1994) Pan-African displaced terranes in the Tuareg shield (central Sahara). Geology 22:641–644CrossRefGoogle Scholar
  5. Bodinier JL, Guiraud M, Dupuy C, Dostal J (1986) Geochemistry of basic dikes in the Lanzo massif (western Alps): petrogenetic and geodynamic implications. Tectonophysics 128:77–95CrossRefGoogle Scholar
  6. Boudier F (1976) Le massif lherzolitique de Lanzo (Alpes picmontaises). Etude structurale et petrologique. These d'Etat, Nantes 163 ppGoogle Scholar
  7. BVTP (1981) Basaltic volcanism on the terrestrial planets. Pergamon Press, New YorkGoogle Scholar
  8. Caby R (1970) La chaine pharusienne dans le nord-ouest de l'Ahaggar (Sahara cenral Algerie); sa place dans l'orogenese du Precambrien superieur en Afrique. These Sciences Montpellier 336 ppGoogle Scholar
  9. Caby R (1983) La chaine pan-africaine dans le Nord-Ouest de l'Ahaggar (Sahara central Algerie) — sa place dans l'orogenese du Precambrien superieur en Afrique. Publ Dir Geol Alger nelle ser Bull 47:1–290Google Scholar
  10. Caby R (1987) The Pan-African belt of the West Africa from the Sahara to the Gulf of Benin. In: Schaer JP, Rodgers J (eds) Anatomy of mountain ranges. Princeton University Press, Princeton, New Jersey, pp 129–170Google Scholar
  11. Caby R (1994) First record of Precambrian coesite from northern Mali: implications for Late Proterozoic plate tectonics around the West African craton. Eur J Mineral 6:235–244CrossRefGoogle Scholar
  12. Caby R, Dostal J, Dupuy C (1977) Upper Proterozoic volcanic graywackes from western Hoggar (Algeria). Geol Geochem Precambr Res 5:283–297CrossRefGoogle Scholar
  13. Caby R, Bertrand JM, Black R (1980) Oceanic closure and continental collision in the Hoggar-Iforas Pan-African segment. In: Kroner A (ed) Precambrian plate tectonics. Elsevier, Amsterdam, pp 407–434Google Scholar
  14. Caby R, Andreopoulos-Renaud U, Pin C (1989) Late Proterozoic arc/continent and continent/continent collision in the trans-Saharan belt. Can J Earth Sci 26:1136–1146CrossRefGoogle Scholar
  15. Chikhaoui M, Dupuy C, Dostal J (1978) Geochemistry of Late Proterozoic volcanic rocks from Tassendjanet area (N.W. Hoggar Algeria). Contrib Mineral Petrol 66:157–164CrossRefGoogle Scholar
  16. Chikhaoui M, Dupuy C, Dostal J (1980) Geochemistry and petrogenesis of Late Proterozoic volcanic rocks from north-western Africa. Contrib Mineral Petrol 73:375–388CrossRefGoogle Scholar
  17. Clauer N (1976) Geochimie isotopique du strontium dans les milieux sedimentaires. Sci Geol 45:1–256Google Scholar
  18. Coish RA, Rogers NW (1987) Geochemistry of the Boil Mountain ophiolitic complex northwest Maine and tectonic implications. Contrib Mineral Petrol 97:51–65CrossRefGoogle Scholar
  19. Conrad W, Kay RW (1984) Ultramafic and mafic inclusions from Adak Island: crystallization history and implications for the nature of primary magmas and crustal evolution in the Aleutian arc. J Petrol 25:88–125CrossRefGoogle Scholar
  20. DeBari SM, Coleman RG (1989) Examination of deep levels from an island arc evidence from the Tonsina assemblage Tonsina Alaska. J Geophys Res 94 (B4): 4373–4391CrossRefGoogle Scholar
  21. Dick HJB, Fisher RL, Bryan WB (1984) Mineralogic variability of the uppermost mantle along mid-ocean ridges. Earth Planet Sci Lett 69:88–106CrossRefGoogle Scholar
  22. Dietrich V, Emmermann R, Oberhansli R, Puchlet H (1978) Geochemistry of basaltic and gabbroic rocks from the eastern Mariana basin and the Mariana trench. Earth Planet Sci Lett 39:127–144CrossRefGoogle Scholar
  23. Dostal J, Muecke GK (1978) Trace element geochemistry of the peridotite-gabbro-basalt suite from DSDP Leg 37. Earth Planet Sci Lett 40:415–422CrossRefGoogle Scholar
  24. Dostal J, Dupuy C, Carron JP, Le Guen De Kerneizon M, Maury RC (1983) Partition coefficients of trace elements: application to volcanic rocks of St. Vincent West Indies. Geochim Cosmochim Acta 47:525–533CrossRefGoogle Scholar
  25. Dostal J, Baragar WRA, Dupuy C (1986) Petrogenesis of the Natkusiak continental basalts Victoria Island N.W.T. Can J Earth Sci 23:622–632CrossRefGoogle Scholar
  26. Dostal J, Dupuy C, Caby R (1994) Geochemistry of the Neoproterozoic Tilemsi belt of the Iforas (Mali Sahara): a crustal section of an oceanic island arc. Precambr Res 65:55–69CrossRefGoogle Scholar
  27. Ewart A (1982) The mineralogy and petrography of Tertiary-Recent orogenic volcanic rocks with special reference to the andesite-basaltic composition range. In: Thorpe RS (ed) Andesites. Wiley, New York, pp 25–98Google Scholar
  28. Gass IG, Lippard SJ, Shelton AW (1984) Ophiolites and oceanic lithosphere. Blackwell, OxfordGoogle Scholar
  29. Harnois L, Morency M (1989). Geochemistry of Mount Orford ophiolite complex northern Appalachians Canada. Chem Geol 77:133–147CrossRefGoogle Scholar
  30. Irvine TN, Baragar WRA (1971) A guide to the chemical classification of the common volcanic rocks. Can J Earth Sci 8:523–548CrossRefGoogle Scholar
  31. Kay SM, Kay RW (1985) Role of crystal cumulates and the oceanic crust in the formation of the lower crust of the Aleutian arc. Geology 13:461–464CrossRefGoogle Scholar
  32. Kay SM, Kay RW (1994) Aleutian magmas in space and time. In: Plafker G, Berg HC (eds) The geology of Alaska: Boulder Colorado Geological Society of America. Geol North Am G-1: 687–722Google Scholar
  33. Lapierre H, Ortiz LE, Abouchami W, Monod O, Coulon C, Zimmermann JL (1992) A crustal section of an intra-oceanic island arc: the Late Jurassic-Early Cretaceous Guanajuato magmatic sequence central Mexico. Earth Planet Sci Lett 108:61–77CrossRefGoogle Scholar
  34. Leake BE (1979) Nomenclature of amphiboles. Mineral Mag 42:533–563CrossRefGoogle Scholar
  35. Lewis JH (1973) Petrology of the ejected plutonic blocks of the Soufriere volcano St. Vincent West Indies. J Petrol 14:81–112CrossRefGoogle Scholar
  36. Moussine-Pouchkine A, Bertrand-Sarfati J, Ball E, Caby R (1988) Les series sedimentaires et volcaniques anorogeniques proterozoiques impliquees dans la chaine pan africaine: la region de l'Adrar Ahnet (NW Hoggar Algerie). J Aft Earth Sci 7:57–75CrossRefGoogle Scholar
  37. Pearce JA, Cann JR (1973) Tectonic setting of basic volcanic rocks determined using trace element analysis. Earth Planet Sci Lett 28:459–469.Google Scholar
  38. Quick JE, Sinigoi S, Mayer A (1994). Emplacement dynamics of a large mafic intrusion in the lower crust Ivrea-Verbano Zone Northern Italy. J Geophys Res 99:21559–21573CrossRefGoogle Scholar
  39. Sinigoi S, Quick JE, Clemens-Knott D, Mayer A, Demarchi G, Mazzucchelli M, Negrini L, Rivalenti G (1994) Chemical evolution of a large mafic intrusion in the lower crust Ivrea-Verbano Zone Northern Italy. J Geophys Res 99:21575–21590CrossRefGoogle Scholar
  40. Suen CJ, Frey FA, Malpas J (1979) Bay of Island ophiolite suite Newfoundland: petrologic and geochemical characteristics with emphasis on rare-earth element geochemistry. Earth Planet Sci Lett 45:337–348CrossRefGoogle Scholar
  41. Sun SS (1982) Chemical composition and origin of the Earth's primitive mantle. Geochim Cosmochim Acta 46:179–192CrossRefGoogle Scholar
  42. Sun SS, McDonough WF (1989) Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: Saunders AD, Norry MJ (eds) Magmatism in the ocean basins. Geol Soc Spec Publ 42:313–345Google Scholar
  43. Veblen DR, Ribbe PH (1982) Amphiboles: petrology and experimental phase relations. Rev Mineral 9B. Mineral Soc Am 390Google Scholar
  44. Voshage H, Hofmann AW, Mazzucchelli M, Rivalenti G, Sinigoi S, Raczek I, Demarchi G (1990) Isotopic evidence from the Ivrea Zone for a hybrid lower crust formed by magmatic underplating. Nature 347:731–736CrossRefGoogle Scholar
  45. Winchester JA, Floyd PA (1977) Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chem Geol 20:325–343CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • J. Dostal
    • 1
  • R. Caby
    • 2
  • C. Dupuy
    • 3
  • C. Mevel
    • 4
  • J. V. Owen
    • 1
  1. 1.Department of GeologySaint Mary's UniversityHalifaxCanada
  2. 2.Laboratoire de TectonophysiqueUniversite de Montpellier II, Sciences et TechniquesMontpellier, Cedex 05France
  3. 3.Centre Geologique et GeophysiqueUniversite de Montpellier II, Sciences et TechniquesMontpellier, Cedex 05France
  4. 4.Laboratoire de PetrologieUniversite P. et M. CurieParis, Cedex 05France

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