Thermobarometric constraints on pressure variations across the Plattengneiss shear zone of the Eastern Alps: Implications for exhumation models during Eoalpine subduction
MetadataShow full item record
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.
Showing items related by title, author, creator and subject.
Reddy, Steven; Wheeler, J.; Cliff, R. (1999)Contacts between rocks recording large differences in metamorphic grade are indicative of major tectonic displacements. Low-P upon high-P contacts are commonly interpreted as extensional (i.e. material points on either ...
Phase equilibria modelling constraints on P-T conditions during fluid catalysed conversion of granulite to eclogite in the Bergen Arcs, NorwayBhowany, K.; Hand, M.; Clark, Christopher; Kelsey, D.; Reddy, Steven; Pearce, M.; Tucker, N.; Morrissey, L. (2017)Exhumed eclogitic crust is rare and exposures that preserve both protoliths and altered domains are limited around the world. Nominally anhydrous Neoproterozoic anorthositic granulites exposed on the island of Holsnøy, ...
Accretion, underplating and exhumation along a subduction interface: From subduction initiation to continental subduction (Tavsanli zone, W. Turkey)Plunder, A.; Agard, P.; Chopin, C.; Pourteau, Amaury; Okay, A. (2015)© 2015 Elsevier B.V.. We herein reappraise the pressure-temperature (PT) evolution of the high-pressure and low-temperature (HP-LT) Tavsanli zone (western Turkey) in order to (i) better characterize rock units exhumed ...