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Na- Ti- Zr- H2O-rich mineral inclusions indicating postcumulus chrome-spinel dissolution and recrystallization in the Western Laouni mafic intrusion, Algeria

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Abstract

Disseminated cumulus chrome spinel in the lower-most olivine orthocumulates from the Western Laouni intrusion (Southern Hoggar, Algeria) contains inclusions of silicates enriched in Mg-Ti-Na and H2O, and Fe-Ti (Zr) rich oxides, occurring either as numerous micro-inclusions or as large solitary cavities. Regardless of the inclusion type, titanian pargasite (or kaersutite) and the sodium analog of phlogopite predominate over orthopyroxene (En86 to En92) and Na-rich plagioclase (An50Ab50 to An7Ab93). Oxide inclusions are magnesian ilmenite (up to 37 mol% MgTiO3), rutile, loveringite (Ca,REE-(Ti,Fe,Cr,Mg,Zr)21O38) and accessory magnesian pseudo-brookite (“kennedyite”); apatite, Fe-Ni-Cu sulfides and alteration products (saussurite, bastite) are also present. Apart from kennedyite, all minerals included in chrome spinel form larger intercumulus crystals in the host rock as well. The micro-inclusions were trapped as the consequence of chrome spinel dissolving against the intercumulus liquid, 150 to 300° C below its liquidus temperature. The solitary cavities are attributed to fluid-assisted solid-state recrystallization of chains of spinel crystals; the role of capillary fluids is demonstrated by both the hydrous nature of solid inclusions and a strong positive correlation between the amphibole content and the abundance of solid inclusions in the rock. Phlogopite locally showing similar optical orientation within and outside the inclusions indicates that spinel was still recrystallizing down to 950° C. In the temperature range 1100-900° C determined for the formation of inclusions, chrome spinel probably trapped various combinations of crystals, liquids and fluids, the respective quantities of which varied greatly over distances of few tens of micrometres in a single spinel. The volume ratio of solids to liquids or to fluids must have been low enough to permit magmatic or hydrothermal reactions, which are otherwise never possible for the larger intercumulus crystals. Hence, the lack of olivine and clinopyroxene as inclusions in spinel while abundant in the host rock suggests that, as trapped, they completely reacted with the residual liquid to form phlogopite and pargasite respectively. Likewise, plagioclase and phlogopite have been enriched in Na against hydrothermal fluids to form albite and Na-phlogopite in the mineral inclusions.

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References

  • Augé T (1987) Chromite deposits in the southern Oman ophiolite. Mineralogical constraints. Mineral Dep 22:1–11

    Google Scholar 

  • Caby R, Bertrand JM (1977) Inventaire et prospective des ressources minérales du Hoggar. 1/000000e geological map. SON-AREM edn

  • Cameron EN (1977) Chromite in the central sector of the Eastern Bushveld complex, South Africa. Am Mineral 62:1082–1096

    Google Scholar 

  • Cameron EN (1979) Titanium bearing oxide minerals of the critical zone of the Eastern Bushveld. Am Mineral 64:140–150

    Google Scholar 

  • Campbell IH, Roeder PL, Dixon JM (1978) Crystal buoyancy in basaltic liquids and other experiments with a centrifuge furnace. Contrib Mineral Petrol 67:369–377

    Google Scholar 

  • Carman JH (1974) Synthetic sodium phlogopites and its two hydrates. Am Mineral 59:261–273

    Google Scholar 

  • Cawthorn RG, Davies G (1983) Experimental data at 3 kbars pressure on parental magma to the Bushveld complex. Contrib Mineral Petrol 83:128–135

    Google Scholar 

  • Clark T (1978) Oxide minerals in the Turnagian ultramafic complex, northwestern British Columbia. Can J Earth Sci 15:1893–1903

    Google Scholar 

  • Cottin JY (1985) The late Pan-African ultramafic intrusions of the Laouni area, Southern Hoggar, Algeria: occurrence and petrological significance. 13th Coloqium of African geology. St. Andrew, Scotland. CIFEG, occasional publication 3:127

    Google Scholar 

  • De Waal SA (1975) The mineralogy, chemistry and certain aspects of the reactivity of chromite from the Bushveld complex, Johannesberg. Nat Inst Metall Repub S Afr Rep 1709:80

    Google Scholar 

  • Dick HJB, Bullen T (1984) Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas. Contrib Mineral Petrol 86:54–76

    Google Scholar 

  • Donville B (1962) Le massif de roches éruptives basiques et ultrabasiques de Laouni Ouest (Hoggar méridional). Bull Soc Geol Fr IV:504–509

    Google Scholar 

  • Dujonc SC, Lagache M (1984) Echanges entre plagioclases et solutions aqueuses de chlorures sodi-calciques à différentes pressions et températures (400–800° C, 1 à 3 kbars). Bull Mineral 107:553–571

    Google Scholar 

  • Fabries J (1979) Spinel-olivine geothermometry in peridotites from ultramafic complexes. Contrib Mineral Petrol 69:329–336

    Google Scholar 

  • Fisk MR, Bence AE (1980) Experimental crystallization of chrome spinel in FAMOUS basalts 527-1-1. Earth Planet Sci Lett 48:111–123

    Google Scholar 

  • Forbes WC, Flower MTF (1974) Phase relations of titan-phlogopite, K3Mg4TiAl2Si6O20(OH)4; a refractory phase in the upper mantle? Earth Planet Sci Lett 22:60–66

    Google Scholar 

  • Helz RT (1982) Experimental studies on amphibole stability. In: Veiblen DV, Ribee PH (eds) Reviews in Mineralogy, vol 9b. Mineral Soc Am, pp 279–346

  • Hill R, Roeder PL (1974) The crystallization of spinel from basaltic liquid as a function of oxygen fugacity. J Geol 82:709–729

    Google Scholar 

  • Holloway JR (1973) The system pargasite-H2O-CO2: a model for melting of a hydrous mineral with a mixed — volatile fluid. I. Experimental results to 8 kbar. Geochim Cosmochim Acta 37:991–1020

    Google Scholar 

  • Hulbert LJ, Von Gruenewaldt G (1985) Textural and compositional features of chromite in the Lower and Critical zones of the Bushveld complex south of Potgietersrus. Econ Geol 80:872–895

    Google Scholar 

  • Irvine TN (1965) Chromian spinel as a petrogenetic indicator. Part I: Theory. Can J Earth Sci 2:648–672

    Google Scholar 

  • Irvine TN (1967) Chromian spinel as a petrogenetic indicator. Part II: petrologic implications. Can J Earth Sci 4:71–103

    Google Scholar 

  • Irvine TN (1975) Crystallization sequences in the Muskox intrusion and other layered intrusions. II. Origin of chromite layers and similar deposits of other magmatic ores. Geochim Cosmochim Acta 39:991–1020

    Google Scholar 

  • Irvine TN (1980) Magmatic infiltration metasomatism, double diffusive fractional crystallization and adcumulus growth in the Muskox intrusions and other layered intrusions. In: Physics of magmatic processes. Princeton University Press, Princeton, NJ, USA

    Google Scholar 

  • Irvine TN (1982) Terminology for layered intrusions. J Petrol 23:127–162

    Google Scholar 

  • Jackson ED (1966) Liquid imiscibility in chromite seam formation: a discussion. Econ Geol 61:777–780

    Google Scholar 

  • Johan Z, Watkinson D (1986) Fluide riche en Na-Cl-C-H-O-N et son rôle dans la concentration des platinoides et de la chromite: exemple de la zone critique du complexe de Bushveld. flème Réunion des Sciences de la Terre, Clermond Ferrand. Soc Geol Fr Paris, p 99

  • Johan Z, Dunlop H, Le Bel L, Robert JL, Volfinger R (1983) Origin of chromite deposits in ophiolitic complexes: evidence for a volatile and Na-rich reducing fluid phase. Fortschr Mineral 61:105–107

    Google Scholar 

  • Kingery WD, Bowen HK, Uhlmann DR (1976) Introduction to ceramics. John Wiley and Sons, New York, p 1032

    Google Scholar 

  • Latouche L (1985) Les collisions intracratoniques et la tectonique tangentielle dans le Pan-Africain du Hoggar Central. In: Evolution geologique de l'Afrique. CIFEG, occasional Publication 4:143–159

    Google Scholar 

  • Leblanc M (1980) Chromite growth, dissolution and deformation from a morphological point of view: SEM investigations. Miner Deposita 15:201–210

    Google Scholar 

  • Legendre O (1982) Minéralogie et géochimie des platinoides dans les chromites ophiolitiques. Unpublished thesis, Paris, p 171

  • Legg CA (1969) Some chromite-ilmenite associations in the Merensky Reef, Transvaal. Am Mineral 54:1347

    Google Scholar 

  • Lehman J (1983) Diffusion between olivine and spinel: application to geothermometry. Earth Planet Sci Lett 64:123–138

    Google Scholar 

  • Lorand JP, Cottin JY (1987a) Ilménite et pseudobrookite (“kennedyite”) fortement magnésiennes dans les cumulais ultrabasiques de l'intrusion stratifiée occidentale de Laouni (Hoggar méridional; Algérie). Bull Mineral 110:373–378

    Google Scholar 

  • Lorand JP, Cottin JY (1987b) A new natural occurrence of zirconolite (CaZrTi2O7) and baddeleyite (ZrO2): the Laouni layered intrusion (Southern Hoggar, Algeria). Mineral Mag (in press)

  • Lorand JP, Cotting JY, Parodi GC (1987) Occurrence and petrological significance of loveringite (Ca,REE) (Ti,Cr,Fe)21O38 in the Western Laouni layered complex (Southern Hoggar, Algeria). Can Mineral 25, part 4 (in press)

  • Luth WC (1967) Studies in the system KALSiO4-Mg2SiO4-SiO2-H2O. I. Inferred phase relations and petrologic implications. J Petrol 8:372–416

    Google Scholar 

  • Macdonald JA (1965) Liquid immiscibility as a factor in chromite seam formation in the Bushveld igneous complex. Econ Geol 60:1674–1685

    Google Scholar 

  • Morette Y, Watkinson D, Robert JL, Johan Z (1984) Rôle des fluides dans la précipitation des spinelles, chromite et magnétite à partir de magmas du Bushveld. Bull Mineral Suppl 107:45

    Google Scholar 

  • Nickel KG, Green DH (1984) The nature of the upper-most mantle beneath Victoria, Australia as deduced from ultramafic xenoliths. In: Kornprobst J (ed) Kimberlites II: the mantle and crust-mantle relationships. Elsevier, pp 161–179

  • Onyeagocha AC (1974) Alteration of chromite from the Twin Sisters dunite, Washington. Am Mineral 59:608–612

    Google Scholar 

  • Orville PM (1972) Plagioclase cation exchange equilibria with aqueous chloride solutions: results at 700° C and 2000 bars in the presence of quartz. Am J Sci 272:232–272

    Google Scholar 

  • Reed SJB (1975) In: Electron microprobe analysis. Cambridge University Press, pp 284–287

  • Roedder E (1979) Fluid inclusions as samples of ore fluids. In: Barnes HL (ed) Geochemistry of hydrothermal ore deposits. New York, Wiley, pp 684–737

    Google Scholar 

  • Roeder PL, Campbell IH (1985) The effect of postcumulus reactions on composition of chrome spinels from the Jimberlana intrusion. J Petrol 26:763–786

    Google Scholar 

  • Schliestedt M, Johannes W, Matthews A (1986) Mechanism and kinetics of cation and oxygen isotope exchange reaction between plagioclase and aqueous chloride solutions. International Symposium of Experimental Mineralogy and Geochemistry, Nancy, 17–19 April. Soc Fr Mineral Cristallogr, pp 124–125

  • Spry A (1969) Metamorphic textures. Pergamon Press, New York, p 350

    Google Scholar 

  • Sunagawa I (1975) Characterization of crystal surfaces by optical microscopy. In: Ueda R, Mullin JB (eds) Crystal growth and characterization, pp 347–359

  • Tait SR, Huppert HE, Sparks RSJ (1984) The role of compositional convection in the formation of adcumulates rocks. Lithos 17:139–146

    Google Scholar 

  • Talkington RW, Watkinson DH, Whittaker PJ, Jones PC (1984) Platinum group minerals and other solid inclusions in chromite of ophiolitic complexes: occurrences and petrological significance. Tschermaks Mineral Petrogr Mitt 32:285–301

    Google Scholar 

  • Thompson RN (1976) Chemistry of ilmenites crystallized within the anhydrous melting range of a tholeiitic andesite at pressures between 5 and 26 kbar. Mineral Mag 40:857–862

    Google Scholar 

  • Thy R (1983) Spinel minerals in transitional and alkali basaltic glasses from Iceland. Contrib Mineral Petrol 83:141–149

    Google Scholar 

  • Volfinger M, Robert JL, Vannier C (1986) Chlorine in micas and amphiboles: an experimental study under hydro-thermal conditions. International Symposium of Experimental Mineralogy and Geochemistry, Nancy, 17–19 April. SFMC edn, p 137

  • Wilson AH (1982) The geology of the Great “Dyke” Zimbabwe; the ultramafic rocks. J Petrol 23:240–292

    Google Scholar 

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Authors and Affiliations

  1. Laboratoire de Minéralogie du Museum National d'Histoire Naturelle de Paris, Unité associée au CNRS n∘ 286, 61 Rue de Buffon, F-75005, Paris, France

    J. P. Lorand

  2. Département de Géologie, IST Université d'Oran Es Senia, Oran, Algerie

    J. Y. Cottin

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  1. J. P. Lorand
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  2. J. Y. Cottin
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Lorand, J.P., Cottin, J.Y. Na- Ti- Zr- H2O-rich mineral inclusions indicating postcumulus chrome-spinel dissolution and recrystallization in the Western Laouni mafic intrusion, Algeria. Contr. Mineral. and Petrol. 97, 251–263 (1987). https://doi.org/10.1007/BF00371244

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