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Deviations from Lithostatic Pressure During Metamorphism: fact or fiction?
Convener: Lucie Tajcmanova  | Co-Conveners: Holger Stunitz , James Connolly 
 / Fri, 02 May, 08:30–12:00
 / Attendance Fri, 02 May, 15:30–17:00
Poster Summaries & DiscussionsPSD23.4 

Mineral reactions have mechanical effects that may result in the development of pressure variations even on a hand specimen or grain scale and thus are critical for interpreting microstructural and mineral composition observations. Such effects may fundamentally influence element transport properties and rheological behavior. Considering the interplay of metamorphic reactions and mechanical properties is therefore critical for a correct interpretation of microstructural observations in metamorphic rocks as well as for quantification of the processes. Recent microstructural observations and mechanical models considering this interplay question our current quantification approach in metamorphic petrology based on the homogeneous pressure assumption. Moreover, recent more common observations of ultra-high-pressure mineral phases in metamorphic rocks also question the simple conversion of pressure estimates into depth through the equation for lithostatic pressure.

Here, we encourage presentations focused on the interplay between metamorphic processes and deformation on all scales, on the rheological behavior of crustal rocks and time scales of metamorphic reactions in order to discuss (1) how and when pressure variations can be maintained at geological timescales, (2) modelling of systems with pressure variations, (3) the impact of non-lithostatic pressure variations on geodynamic reconstructions. Contributions from natural samples, experiments, as well as theoretical and modelling studies are welcome.