Garnet-orthopyroxene assemblages as pressure-temperature indicators ...

• Main Author: Harley, SL
• Format: Thesis
• Language: unknown
• Published: University Of Tasmania 2023
• Subjects: Casey Bay; Napier; Scott Mountains; Antarc*; Antarctica; Enderby Land
• Online Access: https://dx.doi.org/10.25959/23210774; https://figshare.utas.edu.au/articles/thesis/Garnet-orthopyroxene_assemblages_as_pressure-temperature_indicators/23210774

Granulites from the Napier province\ Enderby Land Antarctica were metamorphosed at 900-950 °c and 7-10 kilobars durinq and subsequent to a major tectonothermal episode at 3000 million years before the present. Rocks presently exposed at the surface in southwestern Enderby Land indicate a regional increase in pressures of metamorphism towards the Scott Mountains - Casey Bay region where crustal thicknesses of at least 30 kilometres were attained at that time. Subsequent to the peak granulite facies metamorphic event the Napier province granulites underwent a prolonged phase of near-isobaric cooling at depth to P-T conditions of 650-700°C and 5-8 kilobars by 2500 million years before the present. A study of the pyroxene granulites from the Napier province demonstrates the near-isobaric cooling path in the development of a variety of retrograde corona textures involving the formation of garnet by reactions between pyroxenes plagioclase and opaque phases. Garnet-orthopyroxene bearing felsic and pelitic ...