Enderby land, Antarctica—an unusual Precambrian high‐grade metamorphic terrain

Sheraton, J. W.; Offe, L. A.; Tingey, R. J.; Ellis, David J.

doi:10.1080/00167618008729114

Cited by 144 publications

(139 citation statements)

References 35 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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“…Robertson Lands (summarised by Tingey, 1991). The oldest rocks are granulites of the Napier and Rayner Complexes of Enderby Land, which have been dated as Archaean (chronology summarised by Sheraton et al, 1987). Bedrock exposures along the coast of Kemp Land consist mainly of highgrade granulite facies gneisses intruded by, in some cases, Mesoproterozoic to Neoproterozoic charnockite plutons (Tingey, 1991).…”

Section: Geologymentioning

confidence: 99%

Geology of the Continental Margin of Enderby and Mac. Robertson Lands, East Antarctica: Insights from a Regional Data Set

et al. 2004

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In 2001 and 2002, Australia acquired an integrated geophysical data set over the deep-water continental margin of East Antarctica from west of Enderby Land to offshore from Prydz Bay. The data include approximately 7700 km of high-quality, deep-seismic data with coincident gravity, magnetic and bathymetry data, and 37 non-reversed refraction stations using expendable sonobuoys. Integration of these data with similar quality data recorded by Japan in 1999 allows a new regional interpretation of this sector of the Antarctic margin. This part of the Antarctic continental margin formed during the breakup of the eastern margin of India and East Antarctica, which culminated with the onset of seafloor spreading in the Valanginian. The geology of the Antarctic margin and the adjacent oceanic crust can be divided into distinct east and west sectors by an interpreted crustal boundary at approximately 58°E. Across this boundary, the continent-ocean boundary (COB), defined as the inboard edge of unequivocal oceanic crust, steps outboard from west to east by about 100 km. Structure in the sector west of 58°E is largely controlled by the mixed rift-transform setting. The edge of the onshore ArchaeanProterozoic Napier Complex is downfaulted oceanwards near the shelf edge by at least 6 km and these rocks are interpreted to underlie a rift basin beneath the continental slope. The thickness of rift and pre-rift rocks cannot be accurately determined with the available data, but they appear to be relatively thin. The margin is overlain by a blanket of post-rift sedimentary rocks that are up to 6 km thick beneath the lower continental slope. The COB in this sector is interpreted from the seismic reflection data and potential field modelling to coincide with the base of a basement depression at 8.0-8.5 s two-way time, approximately 170 km oceanwards of the shelf-edge bounding fault system. Oceanic crust in this sector is highly variable in character, from rugged with a relief of more than 1 km over distances of 10-20 km, to rugose with low-amplitude relief set on a long-wavelength undulating basement. The crustal velocity profile appears unusual, with velocities of 7.6-7.95 km s )1 being recorded at several stations at a depth that gives a thickness of crust of only 4 km. If these velocities are from mantle, then the thin crust may be due to the presence of fracture zones. Alternatively, the velocities may be coming from a lower crust that has been heavily altered by the intrusion of mantle rocks. The sector east of 58°E has formed in a normal rifted margin setting, with complexities in the east from the underlying structure of the N-S trending Palaeozoic Lambert Graben. The Napier Complex is downfaulted to depths of 8-10 km beneath the upper continental slope, and the margin rift basin is more than 300 km wide. As in the western sector, the riftstage rocks are probably relatively thin. This part of the margin is blanketed by post-rift sediments that are up to about 8 km thick. The interpreted COB in the eastern sector is the...

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“…Robertson Land, where MAW is located (Fig. 1), late-Proterozoic metamorphic events generated the granulite facies rocks in upper part of the crust (Tingey, 1982;Sheraton et al, 1987). The sharp and fairly deeper Moho around 44 km depth might have a relationship with the metamorphism of the Rayner Complex besides the Archaean Napier Complex.…”

Section: Resultsmentioning

confidence: 99%

Shear Wave Velocity Models Beneath Antarctic Margins Inverted by Genetic Algorithm for Teleseismic Receiver Functions

Kanao¹,

Shibutani²

2012

Seismic Waves - Research and Analysis

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Enderby land, Antarctica—an unusual Precambrian high‐grade metamorphic terrain

Cited by 144 publications

References 35 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

Geology of the Continental Margin of Enderby and Mac. Robertson Lands, East Antarctica: Insights from a Regional Data Set

Shear Wave Velocity Models Beneath Antarctic Margins Inverted by Genetic Algorithm for Teleseismic Receiver Functions

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