Proterozoic and Palaeozoic evolution of the Rauer Group
--- Public Summary from Project --- The Gondwana continent existed in the Proterozoic, that is some 500 million years ago, in which Antarctica - Australia - India were once joined as a large landmass. Today the continents of the Southern Hemisphere are widely separated. This project is to investigat...
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| Format: | Dataset |
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Australian Antarctic Data Centre
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| Online Access: | https://researchdata.ands.org.au/proterozoic-palaeozoic-evolution-rauer-group/699441 https://doi.org/10.4225/15/54B8847D4ECD4 https://data.aad.gov.au/metadata/records/ASAC_1129 http://nla.gov.au/nla.party-617536 |
| Summary: | --- Public Summary from Project --- The Gondwana continent existed in the Proterozoic, that is some 500 million years ago, in which Antarctica - Australia - India were once joined as a large landmass. Today the continents of the Southern Hemisphere are widely separated. This project is to investigate the processes related to the formation and dismemberment of the Gondwana landmass. From the abstracts of some of the referenced papers: Granulite facies metapelites of the Mather and Filla Paragneisses within the Rauer Group, east Antarctica, possess markedly different compositions. The metamorphic evolution of the two metapelite types has been interpreted as temporally distinct, with the Rauer Group preserving at least two distinct granulite facies tectonothermal episodes. Calculated P-T pseudosections and orthopyroxene Al content indicate the revised maximum-preserved P-T conditions within the Mather Paragneiss to lie in the vicinity of 950-975 degrees C and 10-10.6kbar, less extreme than previous estimates. The range of possible P-T paths for the Mather Paragneiss consistent with mineral textural relationships and pseudosections contoured for mineral proportion are significantly shallower (dP/dT) than previous estimates. A near-isothermal decompression P-T path, and extreme peak metamorphic conditions, are not necessary to explain the development of preserved mineral reaction textures. The Filla Paragneiss contains peltic assemblages less amenable to rigorous quantitative analysis. Nevertheless, possibilities for the shared or otherwise metamorphic evolution of the Mather and Filla Paragneisses may be postulated on the basis of calculated pseudosections in the context of existing geochronology for the Rauer Group and preserved microstructures. A shared evolution, most likely during Pan-African granulite facies metamorphism, is plausible and consistent with mineral assemblage development, geochronology and microstructures. A revised interpretation of the Rauer Group's preserved metamorphic evolution may warrant the revision of existing tectonic models, applicable also to the reminder of Prydz Bay. More generally, the employed approach may incite a revision of peak P-T and P-T paths in other granulite facies terranes. Descriptions of the data files are as follows: For Ar data, these are Ar isotopes (36Ar, 37Ar and 39Ar etc) used for Ar age calculation, as it represents important time of cooling and exhumation of the study region. Ca/K ratio is used for excess. For the mineral composition data, each column is weight percent content of main oxides (SiO2, MgO, FeO . ZnO) of each mineral, as they are used for metamorphic condition estimates. RauerProbe2.xls: chemical composition of silicate minerals in granulite-facies rocks from the Rauer Group, Prydz Bay, east Antarctica. Compositions determined by electron microprobe and presented as weight% oxide and element cations. CMPTab1.xls: Uranium, thorium and lead chemical composition (parts per million and/or weight %) of monazite from granulite-facies rocks in the Rauer Group, east Antarctica. The Th-U-Pb chemical age corresponding to the chemical compositions is also presented. JMGTable3.xls: chemical composition of silicate minerals in granulite-facies rocks from the Rauer Group, Prydz Bay, east Antarctica. Compositions determined by electron microprobe and presented as weight% oxide and element cations. JMGTable4.xls: chemical composition of silicate minerals in granulite-facies rocks from the Rauer Group, Prydz Bay, east Antarctica. Compositions determined by electron microprobe and presented as weight% oxide and element cations. JMGTable5.xls: chemical composition of silicate minerals in granulite-facies rocks from the Rauer Group, Prydz Bay, east Antarctica. Compositions determined by electron microprobe and presented as weight% oxide and element cations. RauerProbe1.xls: chemical composition of silicate minerals in granulite-facies rocks from the Rauer Group, Prydz Bay, east Antarctica. Compositions determined by electron microprobe and presented as weight% oxide and element cations. |
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