Granulites from Enderby Land, Antarctica : the application of experimentally determined cation partition data to estimation of pressures and temperatures of metamorphism. ...

• Main Author: Ellis, David John
• Format: Thesis
• Language: unknown
• Published: University Of Tasmania 2023
• Subjects: Antarc*; Antarctica; Enderby Land
• Online Access: https://dx.doi.org/10.25959/23235434.v1; https://figshare.utas.edu.au/articles/thesis/Granulites_from_Enderby_Land_Antarctica_the_application_of_experimentally_determined_cation_partition_data_to_estimation_of_pressures_and_temperatures_of_metamorphism_/23235434/1

The Precambrian granulites of Enderby Land, Antarctica, were metamorphosed at temperatures as high as 900 °C and then underwent slow isobaric cooling at about 10 kb pressure. The mafic and pelitic granulites are characterised by the presence of retrograde reaction coronas, a variety of exsolution assemblages in clinopyroxenes and compositional zoning in minerals. The recognition of staggered closure temperatures of cation exchange for different mineral systems permits the use of geothermometers and geobarometers to evaluate the P-T cooling paths of these granulites. The pelitic rocks contain coexisting spinel-quartz, sapphirine-quartz, hypersthene-sillimanite-quartz and osumilite on a regional scale. Osumilite is present in a variety of mineral assemblages, most of which have not previously been reported. These assemblages have been used to construct theoretical P-T diagrams for the stability of osumilite in the K2O-Mg0-Al2O3 -SiO2 and K2O-FeO-Mg0-Al2O3 -SiO2 chemical systems. Secondary cordierite has ...