Evidences for Polyphased Oceanic Alteration of the Extrusive Sequence of the Semail Ophiolite from the Salahi Block (Northern Oman)

  • C. Pflumio
Part of the Petrology and Structural Geology book series (PESG, volume 5)


The extrusive sequence of the Salahi block (northern Oman) consists of a well-developed dyke complex and thick volcanic member. The latter is composed of three events (V1, V2 and V3). Lenses of pelagic, often metalliferous sediments are present within the lava flows. The largest exposures of these sediments are observed at the interface of the different volcanic units. The V1—V2 contact is also the locus of the fault-controlled, Zuha sulphide prospect.

A strong metamorphic zonation overprints the extrusive sequence of the Salahi block (greenschist-facies assemblage in the dyke complex, prehnitepumpellyite-facies assemblage in the lower part of the volcanic sequence, zeolite-facies and low-temperature assemblages in high stratigraphic level flows). Although the steep thermal gradients and static recrystallization suggest that the observed zonation had developed in response to seawater circulation, the dykes and lava flows alteration differs from that described in oceanic layer 2 in three respects: 1) by the pervasiveness of the recrystallization, 2) by the occurrence of a prehnite-pumpellyite-facies assemblage at the top of the first accretion-related volcanic event (V1), 3) by the relative scarcity of low-temperature minerals and the widespread development of phases uncommon in the modern oceanic crust (i.e. iron-rich pumpellyite) in the high stratigraphic level lavas (V2, V3).

Field observations and mineralogical study indicate that the Salahi block extrusive sequence has been subjected to three stages of hydrothermal circulation and to low-temperature oceanic alteration that were contemporaneous with the three magmatic events of the Semail complex. The superposition of alteration phases accounts for the peculiarities of the metamorphic zonation in the volcanic member of this ophiolite.

The origin of the Zuha mineralized zone is attributed to the hydrothermal phase activated by the second, off-axis, magmatic event. The Zuha prospect displays the characteristics of a hydrothermal discharge zone: sulphide-bearing lavas with a typical stockwork paragenesis (quartz, Fe-chlorite, rectorite, titanite), appear in the uppermost Vl sequence below the gossans. This assemblage results from an interaction between Vl lavas and hot (250–300°C), relatively low pH, metal-loaded, upwelling fluids. After interaction with the volcanics and formation of the sulphide mineralization, the hydrothermal fluids were responsible for the formation of large, Mn-rich, sedimentary lenses at the top of the Vl unit in the vicinity of the mineralized zone.


Hydrothermal Alteration Magmatic Event Volcanic Event Volcanic Sequence Metalliferous Sediment 
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  1. Alabaster, T., Pearce, J.A., Mallick, D.I.J. and Elboushi, I.M., 1980. The volcanic stratigraphy and location of massive sulfide deposits in the Oman ophiolite. In: A. Panayiotou (Ed), Ophiolites, Proceedings of the International Ophiolite Symposium, 1979, Cyprus., Nicosia Ministry of Agriculture Nat. Resources, Geol. survey dept.: 751–757.Google Scholar
  2. Alabaster, T. and Pearce, J.A., 1985. The interrelationship between magmatic and ore-forming hydrothermal processes in the Oman ophiolite., Econ. Geol., 80: 1–16.CrossRefGoogle Scholar
  3. Alleman, F. and Peters, T., 1972. The ophiolite-radiolarite belt of the north-Oman mountains., Eclogae Geol. Helv., 65: 657–698.Google Scholar
  4. Alt, J.C., Honnorez, J., Laverne, C. and Emmermann, N., R., 1986. Hydrothermal alteration of a 1 km section through the upper oceanic crust, DSDP hole 504B: the mineralogy, chemistry and evolution of seawater-basalt interactions., J. Geophys. Res., 91: 10309–10335.CrossRefGoogle Scholar
  5. Alt, J.C., Lonsdale, P., Haymon, R. and Muehlenbach K., 1987. Hydrothermal sulphide and oxide deposits on seamounts near 21°N, East Pacific Rise., Geol. Soc. Am. Bull., 98: 157–168.CrossRefGoogle Scholar
  6. Andrews, A.J., 1980. Saponite and celadonite in layer 2 basalts, D.S.D.P. Leg 37., Contrib. Mineral. Petrol., 73: 323–340.CrossRefGoogle Scholar
  7. Beurrier, M., 1987. Géologie de la nappe ophiolitique de Samail dans les parties orientales et centrale des montagnes d’Oman., Thèse Doc. ès Sci., Université Paris 6, France, document B.R.G.M., 128.Google Scholar
  8. Beurrier, M., Bourdillon de Grissac, C., De Weyer P and Lescuyer J.L., 1987. Biostratigraphie des radiolarites associées aux volcanites ophiolitiques de la nappe de Semail (Sultanat d’Oman): conséquences tectonogénétiques., C. R. Acad. Sci. Paris, 304, Ser. 2: 907–910.Google Scholar
  9. Boles, J.R. and Coombs, D.S., 1977. Zeolite facies alteration of sandstones in the Soouthland syncline, New Zealand., Am. J. Sci., 277: 982–1012.Bonatti, E., 1983. Hydrothermal metal deposits from oceanic rifts: a classification. In: P.A. Rona et al. (Eds), Hydrothermal processes at seafloor spreading centers (NATO, Conf. Ser.), Plenum, New York and London: pp. 491–502Google Scholar
  10. Bostrom, K. and Peterson, M.N.A., 1966. Precipitates from hydrothermal exhalations on the East Pacific rise., Econ. Geol., 61: 1258–1265.CrossRefGoogle Scholar
  11. Boudier, F. and Coleman, R.G., 1981. Cross section through the peridotites in the Semail ophiolite, southeastern Oman mountains., J. Geophys. Res., 86: 2573–2592.CrossRefGoogle Scholar
  12. Boudier, F. and Nicolas, A., 1988. The ophiolites of Oman., Tectonophysics, 151, 1–4.CrossRefGoogle Scholar
  13. Bowers, T.C., Von Damm, K.L. and Edmond, J.M., 1985. Chemical evolution of mid-ocean ridge hot springs., Geochim. Cosmochim. Acta, 49: 2239–2252.CrossRefGoogle Scholar
  14. Cann, J.R., 1969. Spilites from the Carlsberg Ridge, Indian Ocean., J. Petrol., 10: 1–19.CrossRefGoogle Scholar
  15. Cathelineau, M. and Nieva, D., 1985. A chlorite solid solution geothermometer: the Los Azufres (Mexico) geothermal system., Contrib. Mineral. Petrol. 91: 235–244.CrossRefGoogle Scholar
  16. Ceuleneer, G., Nicolas, A. and Boudier, F., 1988. Mantle flow pattern at an oceanic spreading center: the Oman peridotite record. In: F. Boudier and A. Nicolas (Eds), The ophiolites of Oman., Tectonophysics, 151: 1–26.Google Scholar
  17. Coleman, R.G. and Hopson, C. A., 1981. The Oman ophiolite., J. Geoph. Res., 86: 2495–2782.CrossRefGoogle Scholar
  18. Collinson, T., 1986, Hydrothermal mineralization and basalt alteration in stockwork zones of the Bayda and Lasail massive sulphide deposits, Oman Ophiolite. M.A. Thesis, University of California, Santa Barbara.Google Scholar
  19. Coombs, D.S., 1953. The pumpellyite mineral series., Mineral. Mag., 30: 113–135.CrossRefGoogle Scholar
  20. Coombs, D.S., Nakamura, Y. and Vuagnat, M., 1976. Pumpellyite-Actinolite facies Schists of the Taveyanne formation near Loèche, Valais, Switzerland., J. Petrol., 17: 440–471.CrossRefGoogle Scholar
  21. Crovisier, J.L., Thomassin, J.H., Juteau, T., Eberhardt, J.C., Touray, J.C. and Baillif, P., 1983. Experimental seawater-basaltic glass interaction at 50°C: study of the early developed phases by electron microscopy and X-Ray photoelectron spectrometry., Geochim. Cosmochim. Acta, 43: 377–387.CrossRefGoogle Scholar
  22. Date, J., Wanatabe, Y. and Saeki, Y., 1983. Zonal alteration around the Fukazawa Kuroko deposits, Akita prefecture, Northern Japan., Econ. Geol. Mon., 5: 365–386.Google Scholar
  23. Delaney, J.R., Mogk, D.W. and Mottl, M.J., 1987. Quartz-cemented breccias from the Mid-Atlantic Ridge: samples of a high salinity hydrothermal upflow zone., J. Geophys. Res., 92: 9175–9192.CrossRefGoogle Scholar
  24. Detrick, R.S., Honnorez, J., Adamson, A.C., Garrett, W.B., Gillis, K.M., Humphris, S.E., Mevel, C., Meyer, P.S., Petersen, N., Rautenschlein, M., Shibata, T., Staudigel, H., Wool-ridge, A. and Yamamoto, K., 1986. Forages dans la dorsale médio-Atlantique: résultats préliminaires du Leg 106 du Joïdes resolution (Ocean Drilling Program)., C.R. Acad. Sci. Paris, 303, Ser. 2: 379–384.Google Scholar
  25. Elthon, D., 1981. Metamorphism in oceanic spreading centers. In: C. Emiliani (Ed), The Sea, Vol 7, John Wiley: pp. 285–303.Google Scholar
  26. Ernewein, M. and Whitechurch, H., 1986. Les intrusions ultrabasiques de la séquence crustale de l’ophiolite d’Oman: un evènement témoin de l’extinction d’une zone d’accrétion océanique?, C.R. Acad. Sci. Paris, 303, Ser. 2: 379–384.Google Scholar
  27. Ernewein, M., Pflumio, C. and Whitechurch, H., 1988. The death of an accretion zone as evidenced by the magmatic history of the Semail ophiolite (Oman)., Tectonophysics, 151: 245–274.CrossRefGoogle Scholar
  28. Evarts, R.C. and Schiffman, P., 1983. Submarine hydrothermal metamorphism of the Del Puerto ophiolite, California., Am. J. Sci., 283: 289–340.CrossRefGoogle Scholar
  29. Fleet, A.J. and Robertson, A.H.F., 1980. Ocean-ridge metalliferous and pelagic sediments of the Semail nappe, Oman., J. Geol. Soc. London, 137: 403–422.CrossRefGoogle Scholar
  30. Germain-Fournier, B., 1986. Les sédiments métallifères océaniques actuels et anciens: caractérisation, comparaisons. Thèse Université Bretagne occidentale, Brest, France.Google Scholar
  31. Francheteaú, J., Needham, H.D., Choukroune, P., Juteau, T., Seguret, M., Ballard, R.D., Fox, P.J., Normak, W., Carranza, A., Cordoba, D., Guerrero, J. and Rangin, C., Bougault, H., Cambon, P. and Hekinian, R., 1979. Massive deep-sea sulphide ore discovered on the East Pacific Rise., Nature, 277: 523–528.CrossRefGoogle Scholar
  32. Franklin, J.M., Lydon, J.W. and Sangster, D.F., 1981. Volcanic-associated massive sulphide deposits., Econ. Geol. 75th. Anniv. Vol., pp. 485–627.Google Scholar
  33. Ghent, E.D. and Stout, M.Z., 1981. Metamorphism at the base of the Samail ophiolite, southeastern Oman Mountains., J. Geophys. Res., 86: 2557–2571.CrossRefGoogle Scholar
  34. Glassley, W., 1975, Low variance phase relationships in a prehnite - pumpellyite facies terrain., Lithos, 8: 69–76.CrossRefGoogle Scholar
  35. Gillis, K. and Robinson, P.T., 1985. Low temperature alteration of the extrusive sequence, Troodos ophiolite, Cyprus., Can. Min., 23: 431–441.Google Scholar
  36. Glennie, K.W., Boeuf, M.G.A., Hugues-Clark, M.W., Moody-Stuart, M., Pilaar, W.F.H. and Reinhardt, B.M., 1974. Geology of the Oman mountains., Kon. Ned. Geol. Mijbouwk Genoot. Vern., 31.Google Scholar
  37. Green, K.E., Von Hertzen, R.P. and Williams, D.L., 1981. The Galapagos spreading center at 86° N: A detailed geothermal field study., J. Geophys. Res., 86: 979–986.CrossRefGoogle Scholar
  38. Haymon, R.M., Koski, R.A., and Abrams, M.J., 1989. Hydrothermal discharge zones beneath massive sulfide deposits mapped in the Oman ophiolite., Geology, 17: 531–535.CrossRefGoogle Scholar
  39. Hekinian, R. and Fouquet, Y., 1985. Volcanism and metallogenesis of axial and off-axial structures on the East-Pacific Rise near 13°N., Econ. Geol., 80 (2): 221–249.CrossRefGoogle Scholar
  40. Hey, M.H., 1954. A new review of the chlorites., Min. Mag., 30: 277–292.CrossRefGoogle Scholar
  41. Humphris, S.E. and Thompson, G., 1978a. Hydrothermal alteration of oceanic basalts by seawater., Geochim. Cosmochim. Acta, 42: 107–125.CrossRefGoogle Scholar
  42. Humphris, S.E. and Thompson, G., 1978b. Trace element mobility during hydrothermal alteration of oceanic basalts., Geochim. Cosmochim. Acta, 42: 127–136.CrossRefGoogle Scholar
  43. Humphris, S. E., Melson, W.G. and Thompson, R.N., 1980. Basalt weathering on the East Pacific rise and the Galapagos spreading center. Initial Reports of the Deep Sea Drilling Project, 54: 773–788. U.S. Government Printing Office, Washington, D.C.Google Scholar
  44. Ito, E. and Anderson, A.T. Jr, 1983. Submarine metamorphism of gabbros from Mid-Cayman rise: petrographic and mineralogic constraints on hydrothermal processes at slow spreading ridges., Contrib. Mineral. Petrol., 82: 371–388.CrossRefGoogle Scholar
  45. Juteau, T., Ernewein, M., Reuber, I., Whitechurch, H. and Dahl, R., 1988. Duality of magma-tism in the plutonic sequence of the Semail nappe, Oman., Tectonophysics, 151: 107–136.CrossRefGoogle Scholar
  46. Karpoff, A.M., Walter, A.V. and Pflumio, C., 1988. Metalliferous sediments within lava sequences of the Samail ophiolite (Oman): mineralogical and geochemical characterization, origin and evolution., Tectonophysics, 151: 223–246.CrossRefGoogle Scholar
  47. Kerridge, J.F., Haymon, R.M. and Kastner, M., 1983. Sulfur isotope systematics at the 21°N site, East Pacific Rise., Earth Planet. Sci. Lett., 66: 91–100.CrossRefGoogle Scholar
  48. Kuniyoshi, S. and Liou, J.G., 1976. Burial metamorphism of the Karmutsen volcanic rocks, northeastern Vancouver island, British Columbia., Am. J. Sci., 276: 1096–1119.CrossRefGoogle Scholar
  49. Laird, J. and Albee, A. L., 1981. High pressure metamorphism in mafic schists from northern Vermont., Am. J. Sci., 281: 97–126.CrossRefGoogle Scholar
  50. Lanphere, M.A., 1981. K-Ar ages of metamorphic rocks at the base of the Semait ophiolite, Oman., J. Geophys. Res., 86: 2777–2782.CrossRefGoogle Scholar
  51. Laverne, C., 1987. Les interactions basalte-fluides en domaine océanique. Minéralogie, pétrologie et géochimie d’un système hydrothermal: le puit 504B, Pacifique oriental. Thèse Doc. ès. Sci., Université Aix-Marseille, France.Google Scholar
  52. Leake, B.E., 1978. Nomenclature of amphiboles., Am. Min., 63: 1023–1052.Google Scholar
  53. Liou, J.G., 1971. Stilbite-Laumontite equilibrium., Contrib. Mineral. Petrol., 31: 171–177.CrossRefGoogle Scholar
  54. Liou, J.G., 1979. Zeolite facies metamorphism of basaltic rocks from the East Taiwan Ophiolite., Am. Mineral., 64: 1–14.Google Scholar
  55. Liou, J.G., Maruyama, S. and Cho, M, 1985. Phase equilibria and mineral parageneses of metabasites in low-grade metamorphism., Mineral. Mag., 49: 321–333.CrossRefGoogle Scholar
  56. Liou, J.G., Hyung Shik K. and Maruyama, S., 1983. Prehnite-Epidote equilibria and their petrologic applications., J. Petrol., 24: 321–342.CrossRefGoogle Scholar
  57. Lippard, S.J., Shelton, A.W. and Gass, I.G., 1986. The ophiolite of Northern Oman., Geol. Soc., London, Mem., 11.Google Scholar
  58. Mc Culloch, M.T., Gregory, R.T., Wasserburg, G. J. and Taylor, H.P. Jr., 1981. Sm-Nd, Rb-Sr and O16/O18 isotopic systematics in an oceanic crustal section: evidence from the Semail ophiolite., J. Geophys. Res., 86: 2721–2735.CrossRefGoogle Scholar
  59. Merlivat T. L., Pineau, F. and Javoy, M. 1987. Hydrothermal vent waters at 13°N on the East Pacific Rise: isotopic composition and gas concentration., Earth Planet. Sci. Let., 84: 100–108.CrossRefGoogle Scholar
  60. Mevel, C., 1987. Evolution of oceanic gabbros from D.S.D.P. Leg 82: influence of the fluid phase on metamorphic crystallizations., Earth Planet. Sci. Lett., 83: 67–79.CrossRefGoogle Scholar
  61. Mottl, M.J., 1983. Metabasalts, axial hot springs, and the structure of hydrothermal systems at mid-ocean ridges., Geol. Soc. Am. Bull., 94: 161–180.CrossRefGoogle Scholar
  62. Nehlig, P. and Haymon, R., 1987. Microthermometric study of fluid inclusions in a fossil ridge crest, hydrothermal discharge zone in the Bayda area (North Oman Ophiolite)., Eos Trans., A. G. U., 68: 1545.Google Scholar
  63. Nehlig, P. and Juteau, T., 1988. Flow porosities, permeabilities and preliminary data on fluid inclusions and fossil thermal gradients in the crustal sequence of the Semail ophiolite (Oman)., Tectonophysics, V151: 199–221.CrossRefGoogle Scholar
  64. Pallister, J.S., 1981. Structure of the sheeted dyke complex of the Semail Ophiolite near Ibra., J. Geophys. Res., 86: 2661–2672.CrossRefGoogle Scholar
  65. Pearce, J. A., Alabaster, T., Shelton, A.W and Searle, M.P., 1981. The Oman ophiolite as an arc-basin complex: evidence and implications., Trans. R. Soc. London, 300: 299–317.CrossRefGoogle Scholar
  66. Pflumio, C., 1988. Histoire volcanique et hydrothermale du massif de Salahi: implications sur l’origine et l’évolution de l’ophiolite de Sémail (Oman). Thèse, Ecole Nat. Sup des Mines de Paris, France.Google Scholar
  67. Pflumio, C., Michard, A., Whitechurch, H. and Juteau, T., 1990. Petrology of the extrusive sequence of the Salahi block (Northern Oman): implications for the origin and evolution of the Semail ophiolite. Symposium on Ophiolite Genesis and Evolution of the Oceanic Lithosphere, Muscat, Abstracts with program.Google Scholar
  68. Pflumio, C., Juteau, T. and Michard, A., Petrology and geochemistry of the volcanic sequence of the Salahi block (Northern Oman): implications for the origin and evolution of the Semail ophiolite, submitted to Lithos, 1991.Google Scholar
  69. Pisutha-Arnond, V. and Ohmoto, H., 1983. Thermal history and chemical and isotopic compositions of the ore forming fluids responsible for the Kuroko massive sulphide deposits in the Hokuroku district of Japan., Econ. Geol. Mon., 5: 523–558.Google Scholar
  70. Regba, M., Agrinier, P., Pflumio, C., Loubet, M. A geochemical study of an oceanic, hydrothermal discharge zone: the Zuha sulphide prospect in the Salahi block (Semail ophiolite, Oman). This volume.Google Scholar
  71. Richards, H.G., Cann, J.R. and Jensenius, J., 1989. Mineralogical and metasomatic zonation of alteration pipes of Cyprus sulphide deposits. J. Geophys. Res., 84: 91–115.Google Scholar
  72. Richardson, C.J., Cann, J.R., Richards, H.G. and J.G. Cowan, 1987. Metal-depleted root zones of the Troodos ore-forming hydrothermal systems., Cyprus, Earth Planet. Sci. Let., 84: 243–253.CrossRefGoogle Scholar
  73. Robertson, A.H.F., 1976. Origins of ochres and umbers: evidences from Skouriotissa, Troodos massif, Cyprus., Trans. Inst. Min. Metall. Sec. B, Appl. Earth Sci.: 245–251.Google Scholar
  74. Robertson, A.H.F. and Fleet, A.J., 1986. Geochemistry and paleo-oceanography of metalliferous and pelagic sediments from the late cretaceous Oman ophiolite., Mar. Petrol. Geol., 3: 315–337.CrossRefGoogle Scholar
  75. Sayles, F.L. and Bischoff, J.L., 1973. Ferromanganoan sediments in the equatorial East Pacific Rise., Earth Planet. Sci. Lett.: 19, 330–336.CrossRefGoogle Scholar
  76. Seyfried, W.E. et, Bischoff, J.L., 1977. Hydrothermal transport of heavy metals by seawater: the role of seawater/basalt ratio., Earth Planet. Sci. Lett., 34: 71–77.CrossRefGoogle Scholar
  77. Seyfried, W. E., and Mottl, M. J., 1982. Hydrothermal alteration of basalt by seawater under seawater dominated conditions., Geochim. Cosmochim. Acta, V46: 985–1002.CrossRefGoogle Scholar
  78. Seyfried, W. E. and Janecky, D.R., 1985. Heavy metal and sulfur transport during subcritical and supercritical hydrothermal alteration of basalt: influence of fluid pressure and basalt composition and crystallinity., Geochim. Cosmochim. Acta, 49: 2545–2560.CrossRefGoogle Scholar
  79. Stakes, D.S. and O’Neil, J.R., 1982. Mineralogy and stable isotope geochemistry of hydrothermally altered oceanic rocks., Earth Planet. Sci. Lett., 57: 285–304.CrossRefGoogle Scholar
  80. Stern, C. and Elthon, D., 1979. Vertical variations in the effects of hydrothermal metamorphism in Chilean ophiolites: Their implications for ocean floor metamorphism., Tectonophysics, 55: 179–213.CrossRefGoogle Scholar
  81. Thorette, J., 1986. Contribution à l’étude de l’hydrothermalisme océanique: exemple du district minéralisé de York Harbour (ophiolite de Blow-me-Down, Bay of Island, Terre -Neuve). Thèse, Ecole Nat. Sup. Mines Paris, France.Google Scholar
  82. Tippit, P.R., Pessagno, E.A. Jr. and Smewing, J.D., 1981. The biostratigraphy of sediments in the volcanic unit of the Semail ophiolite., J. Geophys. Res., 86: 2756–2762.CrossRefGoogle Scholar
  83. Tuffar, W., Tuffar, E. and Lange, J., 1986. Ore paragenesis of recent hydrothermal deposits at the Cocos-Nazca plate boundary (Galapagos rift) at 85°51’ and 85°55’W: complex massive sulfide mineralizations and mineralized basalts., Geol. Rundschau, 75: 829–861.CrossRefGoogle Scholar
  84. Urabe, T., Scott S.D., and Hattori, K., 1983. A comparison of footwall-rock alteration and geothermal systems beneath some Japanese and Canadian volcanogenic massive sulfide deposits., Econ. Geol. Mon., 5: 345–364.Google Scholar
  85. Wise, W.S. and Eugster, H.P., 1964. Celadonites: synthesis, thermal stability and occurrences., Am. Min., 49: 1031–1083.Google Scholar
  86. Wolery, T.J. and Sleep, T.J., 1976. Hydrothermal circulation and geochemical flux at mid-ocean ridges., J. Geol., 84: 249–275.CrossRefGoogle Scholar

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© Springer Science+Business Media Dordrecht 1991

Authors and Affiliations

  • C. Pflumio
    • 1
  1. 1.Ecole Nationale supérieure des Mines de ParisC.G.G.M.Paris Cedex 06France

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