Thermobarometric constraints on pressure variations across the Plattengneiss shear zone of the Eastern Alps: Implications for exhumation models during Eoalpine subduction
|dc.identifier.citation||Eberlei, T. and Johnson, T. and White, R. and Roffeis, C. and Stüwe, K. 2014. Thermobarometric constraints on pressure variations across the Plattengneiss shear zone of the Eastern Alps: Implications for exhumation models during Eoalpine subduction. Journal of Metamorphic Geology. 32 (2): pp. 227-244.|
Forward and inverse mineral equilibria modelling of metapelitic rocks in the hangingwall and footwall of the Plattengneiss, a major shear zone in the Eastern Alps, are used to constrain their tectonometamorphic evolution and assess models for their exhumation. Forward (pseudosection) modelling of two metapelitic rocks suggests a steep clockwise P–T path with a near-isothermal decompression segment from a pressure peak at around 18–19 kbar and 670°C to the metamorphic peak at 680–720°C and 11–13 kbar. A subsequent decrease to 600–645°C and 8–9 kbar is inferred from the late growth of staurolite in some samples. Conventional thermobarometric calculations (inverse modelling) on 18 samples with the inferred peak assemblage garnet + plagioclase + muscovite + biotite + quartz + rutile ± ilmenite ± kyanite are associated with large 2s uncertainties, and absolute pressures calculated for all samples are statistically indistinguishable. However, calculations constraining relative pressure differences (?P) between samples sharing a common mineral assemblage are associated with much smaller uncertainties and yield pressure differences that are statistically meaningful. Although the overall pattern is complicated, the results suggest a pressure gradient of up to 3 kbar across the shear zone that is consistent with volume loss and a model of exhumation related to slab extraction for the Plattengneiss shear zone.
|dc.publisher||Wiley - Blackwell|
|dc.subject||mineral equilibria modelling|
|dc.title||Thermobarometric constraints on pressure variations across the Plattengneiss shear zone of the Eastern Alps: Implications for exhumation models during Eoalpine subduction|
|dcterms.source.title||Journal of Metamorphic Geology|
|curtin.department||Department of Applied Geology|