Deformation mechanism maps for feldspar rocks

摘要: Abstract Deformation mechanism maps for feldspar rocks were constructed based on recently published constitutive laws dislocation and grain boundary diffusion creep of wet dry plagioclase aggregates. The display constant temperature contours in stress-grain size space strain rates ranging from 10 −16 to −12 s −1 . Two fields dominance diffusion-controlled are separated by a strongly size-sensitive transition zone. For rocks, dominates below about 0.1–1 mm, depending temperature, stress, rate composition. Plagioclase aggregates containing up 0.3 wt.% water as often found natural feldspars more than 2 orders magnitude weaker rocks. strength water-bearing is moderately dependent composition fugacity. range 10–50 μm commonly observed ultramylonites, the deformation predict that dominant at greenschist granulite facies conditions. Low viscosity estimates 18 –10 19 Pa·s modeling postseismic stress relaxation channel flow continental lower crust can only be reconciled with laboratory experiments assuming high temperatures >900 °C or, temperatures, fine-grained possibly localized abundant shear zones. similar thermodynamic conditions size, crustal predicted less order upper mantle