Osumilite-sapphirine-quartz granulites from Enderby Land Antarctica ? Mineral assemblages and reactions

Ellis, David J.; Sheraton, J. W.; England, R. N.; Dallwitz, W. B.

doi:10.1007/bf00399473

Cited by 176 publications

(98 citation statements)

References 30 publications

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“…Osumilite have been reported from not many granulite terranes through out the world. Its important occurrences were documented from different localities in East Antarctica (e.g., Ellis et al, 1980;Sheraton et al, 1980;Grew, 1982;Harley and Hensen, 1990;Hensen and Motoyoshi, 1992;Osanai et al, 2001). Other than these, osumilite or its psudomorphs have also been reported from a few localities from some other parts of the world.…”

Section: Discussionmentioning

confidence: 99%

Osumilite and spinel+quartz from Sri Lanka: Implications for UHT conditions and retrograde P-T path

Sajeev

Osanai²

2004

Journal of Mineralogical and Petrological Sciences

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We report here the occurrence of osumilite as fine isolated inclusions in garnet porphyroblasts from a granulite facies rock in the southwestern part of the Highland Complex in Sri Lanka. Garnet porphyroblasts in the matrix are partly rimmed by sillimanite biotite K feldspar assemblage as well as cordierite K feldspar quartz assemblage. Spinel coexisting with quartz is also observed in the same sample. The pressure temperature condition must be above 950°C at around 7 kbar pressure, on the basis of osumilite stability in KFMASH system. The cooling and decompression continued down to 850°C, into the biotite sillimanite K feldspar quartz stability field. During decompression f o2 must have increased leading to the stability of Zn rich spinel with quartz after cordierite. Our findings provide direct evidence for ultrahigh temperature (UHT) metamorphic conditions in southwestern Highland Complex, and also suggest the existence of a possible UHT zone within the high grade terrane of Sri Lanka.

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Section: Discussionmentioning

confidence: 99%

Osumilite and spinel+quartz from Sri Lanka: Implications for UHT conditions and retrograde P-T path

Sajeev

Osanai²

2004

Journal of Mineralogical and Petrological Sciences

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“…In addition, sapphirine, orthopyroxene, sillimanite, cordierite, ilmenite and magnetite are also present. The spinel bearing quartzites occur within the same area where sapphirine + quartz as well as osumilite have been reported (Ellis et al 1980;Motoyoshi and Matsueda, 1987). The peak metamorphic conditions estimated for the area are 950 1050°C and 7 10 kbars (Motoyoshi et al 1990).…”

Section: The Archaean Napier Complex Antarcticamentioning

confidence: 65%

“…Corundum and quartz are observed either in direct contact or separated by a thin rim of sillimanite. These rocks are characterised by the presence of spinel + quartz assemblage in equilibrium, which is interpreted as typical of the high temperature stage of metamorphism in the area (Ellis et al 1980). In addition, sapphirine, orthopyroxene, sillimanite, cordierite, ilmenite and magnetite are also present.…”

Section: The Archaean Napier Complex Antarcticamentioning

confidence: 99%

Review on "corundum+quartz" assemblage in nature: Possible indicator of ultra-high temperature conditions?

Mouri

Guiraud²,

Osanai

2004

Journal of Mineralogical and Petrological Sciences

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Corundum + quartz as an assemblage has been reported in a limited number of high to ultra high grade metamorphic terrains. It is worth noting that rocks hosting this unusual assemblage have common features with respect to mineral assemblages, textures, metamorphic conditions and geological environments. In addition to corundum and quartz, these rocks are characterised by variable amounts of magnetite, spinel, ilmenite together with rutile and sillimanite/kyanite in Fe rich rocks; and sapphirine, orthopyroxene, garnet and cordierite in more Mg rich rocks. These rocks are characterised in general by (i) coarse grained texture with inclusions of corundum and spinel in magnetite, (ii) sharp contact between corundum and quartz and/or separated by a thin rim of sillimanite or kyanite between these two minerals, (iii) presence of spinel + quartz, sapphirine + quartz in equilibrium as well as osumilite. Although there has been some discussions in the past concerning whether "corundum + quartz" assemblage represents a "thermodynamic" stable or metastable assemblage, it is clear that this assemblage observed mainly in the magnetite ilmenite spinel bearing rocks is "texturally" stable. On the basis of the available experimental and thermodynamic data as well as natural occurrences, we conclude that this assemblage is consistent with ultra high temperature metamorphic environments (up to 1100°C at pressure of 7 to 12 kbars). Therefore, its presence in natural rocks should draw close attention from field metamorphic petrologists working on deep crustal processes.

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“…1) and is an ultrahigh temperature (UHT) metamorphic terrane characterized by mineral assemblages involving combinations of sapphirine, garnet, aluminous orthopyroxene, cordierite, sillimanite, spinel, quartz and osumilite (e.g., Dallwitz, 1968;Sheraton et al, 1980;1987;Ellis et al, 1980;Harley, 1985;1987;1998;Sandiford, 1985;Sandiford and Powell, 1986). Harley and Motoyoshi (2000) pointed out that the sapphirine quartz rocks from Mt.…”

Section: Introductionmentioning

confidence: 99%

Experimental constraints of metamorphic pressure and temperature, and phase relations of a phlogopite-bearing orthopyroxene granulite from Howard Hills, Napier Complex, East Antarctica

Sato

Miyamoto

Kawasaki

2004

Journal of Mineralogical and Petrological Sciences

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High pressure and high temperature experiments were carried out at 9 13 kbar and 950 1200°C using a piston cylinder apparatus, simulating the equilibrium conditions of a phlogopite bearing orthopyroxene granulite from the Howard Hills, Napier Complex, East Antarctica. This granulite consists of orthopyroxene, sapphirine, spinel, alkali feldspar and F rich phlogopite with minor amounts of plagioclase, rutile and quartz, and is garnet free.The experiments clarified the equilibrium phase relations of the phlogopite bearing orthopyroxene granulite under ultrahigh temperature metamorphism conditions. The following mineral assemblages were obtained with decreasing temperature: orthopyroxene + spinel + liquid, orthopyroxene + phlogopite + spinel + liquid, orthopyroxene + phlogopite + sapphirine + spinel + rutile + liquid, orthopyroxene + alkali feldspar + phlogopite + sapphirine + spinel + rutile, orthopyroxene + alkali feldspar + plagioclase + phlogopite + sapphirine + spinel + rutile. Liquid was found in run products at 9 kbar and temperatures of ≥1100°C, and at pressures of 11 13 kbar and 1150°C. At higher pressure, garnet coexists with orthopyroxene, alkali feldspar, plagioclase, phlogopite, sapphirine, rutile and spinel. These experimental results constrain the P T conditions of garnet free, phlogopite bearing orthopyroxene granulite from the Howard Hills.

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Osumilite-sapphirine-quartz granulites from Enderby Land Antarctica ? Mineral assemblages and reactions

Cited by 176 publications

References 30 publications

Osumilite and spinel+quartz from Sri Lanka: Implications for UHT conditions and retrograde P-T path

Osumilite and spinel+quartz from Sri Lanka: Implications for UHT conditions and retrograde P-T path

Review on "corundum+quartz" assemblage in nature: Possible indicator of ultra-high temperature conditions?

Experimental constraints of metamorphic pressure and temperature, and phase relations of a phlogopite-bearing orthopyroxene granulite from Howard Hills, Napier Complex, East Antarctica

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