Abstract
The eastern end of the Haylayn massif exposes a complex paleoridge structure interpreted as the tip of a northwestward propagating segment (Nicolas et al., this issue). The area, revisited from a petrostructural and geochemical viewpoint, offers the most documented exposures of the association of olivine gabbros and gabbronorites in Oman (Juteau et al., 1988). Gabbronorites were injected while the main gabbro unit was deforming in the magmatic state. Both units do not differ chemically, except for the SiO2 enrichment of the orthopyroxene-rich gabbros relative to olivine-gabbro. In addition, they display the same trace element signature, which implies the same parent magma for both units. The extension of the stability field of orthopyroxene is assigned to increase of oxygen fugacity due to hydration. The source of hydration is the ridge axis hydrothermal circulation, suggesting hydrothermal/magma interaction at temperatures above the gabbro solidus. The distribution of gabbronorites at the scale of the entire ophiolite suggests a relation with ridge tectonics where high-T conditions of hydrothermal-magmatic interaction are met. Such conditions are met when propagating segments rotate the structures of the dying magma chamber.
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References
Amri, I., Benoit, M. and G. Ceuleneer, 1996, Tectonic setting for the genesis of oceanic plagiogranites: evidence from a paleospreading structure in the Oman ophiolite, Earth Planet. Sc. Lett. 139, 177–194, 1996.
Albarède, F. and Bottinga, Y., 1972, Kinetic deseliquibrium in trace elements partitioning between phenocrysts and host lava, Geochim. Cosmochim. Acta 36: 141–156.
Bédard, J.H., 1993, Oceanic crust as a reactive filter: Synkinematic intrusion, hybridization, and assimilation in an ophiolitic magma chamber, western Newfoundland, Geology 21: 77–80.
Benoit, M., Polvé, M. and Ceuleneer, G., 1996, Trace element and isotopic characterization of mafic cumilates in a fossil mantle diapir (Oman ophiolite), Chem. Geol. 134: 199–214.
Boudier, F., Nicolas, A. and Ildefonse, B., 1996, Magma chambers in the Oman ophiolite: fed from the top or from the bottom?, Earth Planet. Sci. Lett. 144: 239–250.
Boudier, F., Nicolas, A., Ildefonse, B. and Jousselin, D., 1997, EPR microplates, a model for the Oman Ophiolite, Terra Nova 9: 79–82.
Browning, P., 1982, The petrology, geochemistry and structure of the plutonic rocks of the Oman ophiolite, Ph. D. Thesis thesis, Open University.
Browning, P., 1984, Cryptic variation within the cumulate sequence of the Oman ophiolite: magma chamber depth and petrological implications, in I.G. Gass, S.J. Lippard and A.W. Shelton (eds) Ophiolites and oceanic lithosphere, pp. 71–82.
Chenevez, J., Machetel, P. and Nicolas, A. 1998, Numerical models of magma chamber in the Oman ophiolite, Earth and Planet. Sciences Letters 103: 15 443–15 455.
Chenevez, J. and Nicolas, A. 1997, Crustal feeding in the Oman ophiolite: from top and from bottom? A thermal and mass balance model, Earth Planetary Sciences Letters 24: 1811–1814.
Detrick, R.S., Bulh, P., Vera, E., Mutter, J., Orcutt, J., Madsen, J. and Trocher, T., 1987, Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise, Nature 326: 35–41.
Dewey, J.F. and Kidd, W.S.F., 1977, Geometry of plate accretion, Geol. Soc. Am. Bull. 88: 960–968.
Ernewein, M., Pflumio, C. and Whitechurch, H., 1988, The death of an accretion zone as evidenced by the magmatic history of the Sumail ophiolite (Oman), Tectonophysics 151: 247–274.
Gillis, C.M. and Roberts, M.D., 1999, Cracking at the magmahydrothermal transition: evidence from the Troodos ophiolite, Cyprus, Earth Planet. Sc. Lett. 169: 227–244.
Gillis, K., Mével, C., Allan, J. et al., 1993, Proc. ODP Init. Repts, edited by O.D. Program, College Station TX, pp. 366.
Gregory, R.T. and Taylor, H.P., 1981, An oxygen isotope profile in a section of Cretaceaou oceanic crust, Samail ophiolite, Oman: Evidence for d18O buffering of the ocean by deep (>5 km) seawater hydrothermal circulation at Mid-Ocean Ridges, J. Geophys. Res. 86, 2737–2755.
Grove, T.L. and Baker, M.B., 1984, Phase equilibrium controls on the tholeitic versus calc-alkaline differenciation trends, J. Geophys. Res. 89: 3253–3274.
Harding, A.J., Orcutt, J.A., Kappus, M.E., Vera, E.E., Mutter, J.C., Buhl, P., Detrick, R.S. and Brocher, T.M., 1989, Structure of young oceanic crust at 13°N on the East Pacific Rise from expanding spread profiles, J. Geophys. Res. 94: 12,163–12,196.
Hooft, E.E. and Detrick, R.S., 1993, The role of density in the accumuation of basaltic melts at Mid-Ocean Ridges, Geophys. Res. Lett. 20: 423–426.
Ionov, D.A., Savoyant, L. and Dupuy, C., 1992, Application of the ICP-MS technique to trace element analysis of peridotites and their minerals, Geostand. Newslett. 16: 311–315.
Juster, T.C., Grove, T.L. and Perfit, M.R., 1989, Experimental constraints on generation of Fe-Ti basalts, andesites and rhyodacites at the galapagos spreading centre 85 W and 95 W, J. Geophys. Res. 94: 9251–9274.
Juteau, T., Beurrier, M., Dahl, R. and Nehlig, P., 1988, Segmentation at a fossil spreading axis: The plutonic sequence of the Wadi Haymiliyah area (Haylayn block, Sumail nappe, Oman), Tectonophysics, 151: 167–197.
Juteau, T., Ernewein, M., Reuber, I., Whitechurch, H. and Dahl, R., 1988, Duality of magmatism in the plutonic sequence of the Sumail nappe, Oman, Tectonophysics 151: 107–135.
Kelemen, P.B., Koga, K. and Shimizu, N., 1997, Geochemistry of gabbro sills in the crust/mantle transition zone of the Oman ophiolite: Implications for the origin of the oceanic lower crust, Earth Planet. Sci. Lett. 146: 475–488.
Kelley, D.S., and Malpas, J., 1996, Melt-fluid evolution in gabbroic rocks from Hess Deep, in C. Mével, C. Gillis, K.M. Allan and P.S. Meyer (eds) Proc. ODP, Sci. Results, Texas A&M University, College Station, TX, USA, pp. 213–226.
Lachize, M., Lorand, J.-P. and Pattou, L., 1995, Géochimie des métaux nobles (Au et éléments du groupe du platine), cuivre et soufre dans les gabbros lités et les roches ultramafiques intrusives de l'ophiolite d'Oman, C.R. Acad. Sci. Paris 320: 23–30.
Lachize, M., Lorand, J.P. and Juteau, T., 1991, Cu-Ni-PGE magmatic sulfide ores and their host layered gabbros in the Haymiliyah fossil magma chamber (Haylayn block, Semail ophiolite nappe, Oman), in Tj. Peters, A. Nicolas and R.G. Coleman (eds) Ophiolite genesis and evolution of the oceanic listhosphere, Kluwer, pp. 200–229.
Lachize, M., Lorand, J.P. and Juteau, T., 1996, Calc-alkaline differentiation trend in the plutonic sequence of the Wadi Haymilyiah section, Haylayn massif, Semail ophiolite, Oman, Lithos, 38: 207–232.
Lécuyer, C. and Gruau, G., 1996, Oxygen and strontium isotope compositions of Hess Deep gabbros (Holes 894F and 894G): high-temperature interaction of sea-water with the oceanic crust layer 3, in C. Mével, C. Gillis, K.M. Allan and P.S. Meyer (eds) Proc. ODP, Sci. Results, Texas A&M University, College Station, TX, USA, pp. 227–234.
Lippard, S.J., Shelton, A.W. and Gass, I.G., 1986, The Ophiolite of Northern Oman, in Geological Society Memoir, Blackwell, London, pp. 178.
MacLeod, C.J., and Reuber, I., 1990, Complex rift geometry in the northern Oman ophiolite: a possible overlapping spreading center?, in Tj. Peters, A. Nicolas and R.G. Coleman (eds) Ophiolite Genesis and Evolution of Oceanic Lithosphere, Kluwer, pp. 200–229.
MacLeod, C.J. and Rothery, D.A., 1992, Ridge axial segmentation in the Oman ophiolite: evidence from along-strike variations in the sheeted dyke complex, in L.M. Parson, B.J. Murton and P. Browning (eds) Ophiolites and their modern oceanic analogues, Geological Society Special Publications, London, pp. 39–63.
MacLeod, C.J., and Yaouancq, G., 2000, A fossil melt lens in the Oman ophiolite: Implications for magma chamber processess at fast spreading ridges, Earth Planet. Sc. Lett. 176: 357–373.
Mainprice, D, 1997, Modelling the anisotropic seismic properties of partially molten rocks found at mid-oceanic ridges, Tectonophysics 279: 161–180.
Manning, C.E., Weston, P.E. and K.I. Mahon, 1996, Rapid hightemperature metamorphism of East Pacific Rise gabbros from Hess Deep., Earth Planet. Sc. Lett. 144: 123–132.
Mével, C., and Cannat, M., 1991, Lithospheric streching and hydrothermal processes in oceanic gabbros from slow-spreading ridges, in Tj. Peters, A. Nicolas and R.G. Coleman (eds) Ophiolite genesis and evolution of the oceanic listhosphere, Kluwer, pp. 293–312.
Nehlig, P., 1991, Salinity of oceanic hydrothermal fluids: a fluid inclusion study, Earth Palnet. Sc. Lett. 102: 310–325.
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 Sumail ophiolite (Oman), Tectonophysics 151: 199–221.
Nicolas, A., and Boudier, F., 1991, Rooting of the sheeted dike complex in Oman ophiolite., in Tj. Peters, A. Nicolas and R.G. Coleman (eds) Ophiolite genesis and evolution of the oceanic listhosphere, Kluwer, pp. 39–54.
Nicolas, A. and Boudier, F., 1995, Mapping oceanic ridge segments in Oman ophiolites, J. Geophys. Res. 100: 6179–6197.
Nicolas A., Freydier, C.L., Godard, M. and Vauchez, A., 1993, Magma chambers at ocean ridges: How large?, Geology 21: 53–56.
Nicolas, A. and Boudier, F., in press, Large mantle upwellings and related variations in crustal thickness in the Oman ophiolite, Geological Society American Bulletin.
Nicolas, A., Boudier, F., Ildefonse, B. and Ball, E., 2000, Accretion of Oman ophiolite in a microplate system-discussion of a new structural map, Mar. Geophys. Res. 21: 147–179 (this issue).
Nicolas, A., Ceuleneer, G., Boudier, F. and Misseri, M., 1988, Structural mapping in the Oman Ophiolites: mantle diapirism along an oceanic ridge, Tectonophysics 151: 27–56.
Pallister, J.S. and Hopson, C.A., 1981, Samail ophiolite plutonic suite: field relations, phase variation, cryptic variation and layering, and a model of a spreading ridge magma chamber, J. Geophys. Res. 86: 2593–2644.
Pallister, J.S. and Knight, R.J., 1981, Rare Elements Geochemistry of the Samail Ophiolite near Ibra, Oman, J. Geophys. Res. 86: 2673–2697.
Phipps Morgan, J. and Chen, Y.J., 1993, The genesis of oceanic crust: magma injection, hydrothermal circulation and crustal flow, J. Geophys. Res. 98: 6283–6297.
Quick, J.E. and Denlinger, R.P., 1993, Ductile deformation and the origin of layered gabbro in ophiolites, J. Geophys. Res. 98: 14015–14027.
Reuber, I., 1988, Complexity of the crustal sequence in northern Oman ophiolite (Fizh and southern Aswad block: the effect of early slicing? Tectonophysics 151: 137–165.
Reuber, I., 1991, Geometry and flow pattern of the plutonic sequence of the Salahi massif (Northern Oman Ophiolite) – A key to Decipher successive magmatic events, in Tj. Peters, A. Nicolas and R.G. Coleman (eds) Ophiolite genesis and evolution of the oceanic lithosphere Kluwer, pp. 517–542.
Sinton, J.M. and Detrick, R.S., 1992, Mid-ocean ridge magma chambers, J. Geophys. Res. 97: 197–216.
Sleep, N.H., 1975, Formation of oceanic crust; some thermal constraints, J. Geophys. Res. 80: 4037–4022.
Smewing, J.D., 1981, Mixing characteristics and compositional differences in mantle-derived melts beneath spreading axes: evidence from cyclically layered rocks in the ophiolite of North Oman, J. Geophys. Res. 86: 2645–2660.
Staudigel, H., Plank, T., White, B. and Schmincke, H.-U., 1996, Geochemical fluxes during seafloor alteration of the basaltic upper oceanic crust: DSDP Sites 417 and 418, in G.E. Bebout, D.W. School, S.H. Kirby and J.P. Platt (eds) Subduction: Top to Bottom, AGU Monograph, pp. 19–38.
Sun, S.S. and McDonough, W.F., 1989, Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes, in A.D. Saunders and M.J. Norry (eds) Magmatism in the ocean basins, Geol. Soc. London, London, pp. 313–345.
Wilcock, W.S.D., Solomon, S.C., Purdy, G.M. and Toomey, D.R., 1995, Seismic attenuation structure of the East Pacific Rise near 9°30′ N. J. Geophys. Res. 100: 24147–24175.
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Boudier, F., Godard, M. & Armbruster, C. Significance of gabbronorite occurrence in the crustal section of the Semail ophiolite. Marine Geophysical Researches 21, 307–326 (2000). https://doi.org/10.1023/A:1026726232402
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DOI: https://doi.org/10.1023/A:1026726232402