Thermodynamic models for high-temperature metamorphism of metabasic and intermediate rocks
Final Report Abstract
At high temperatures (>650°C) rocks in the Earth's crust can undergo partial melting, with the melt produced commonly leaving the source region and forming granitic bodies or their volcanic equivalents. As such processes cannot be directly observed it is necessary to try and understand them via experiments and/or modelling. Thermodynamic modelling has proven a useful tool for better understanding such processes but has been limited by the need to have robust thermodynamic models for all the minerals involved. The inability of existing mineral thermodynamic models to be applied to high temperature processes and melting of mafic rocks has been an outstanding limitation in understanding high-temperature processes in the Earth's crust. This work successfully addressed this shortcoming and provides the thermodynamic framework in which to better understand the deep crust. New models have been developed for hornblende, clinopyroxene and silicate melt that allow thermodynamic modelling of mafic to intermediate rock compositions. The models predict the melt production of these rocks as a function of Pressure-Temperature and bulk rock composition. The melting of mafic rocks is particularly important for the early Earth as the oldest continental crust was produced via partial melting of basalt precursors. The models faithfully reproduce the tonalitic-tronjhemitic-granodioritic compositions measured from Archaean rocks worldwide.
Publications
- 2014. Back to the metabasics. International Innovation magazine, 32, 102104
White, R.W.
