Fig. 5: Deformation mechanisms and rheological properties of metachert block and calcschist matrix. | Nature Communications

Fig. 5: Deformation mechanisms and rheological properties of metachert block and calcschist matrix.

From: Stress heterogeneities in exhumed high-pressure rocks shed light on deep subduction interface transient coupling

Fig. 5

a Deformation mechanism map under constrained P-T conditions (~1.5 GPa, 490 °C) of the metachert block. The red line represents the boundary between fields of pressure solution and dislocation creep, while the black dotted line represents the “sliding resolution” piezometer of Cross et al.39. Discussions and derivation details are provided in the main text and supplementary material, respectively. b Rheological diagram for flow stress versus depth in the quartz veins (matrix) and metachert (block). Byerlee’s Law is given for pore fluid factor values (λ) of 0.86 and 0.97. Strain rate (\(\dot{\varepsilon }\)) contours of 10-8–10-12 s-1 are calculated using quartz flow laws from Hirth et al.81. The frictional Byerlee’s Law83 is calculated using a friction coefficient of 0.7, with the geostatic gradient is 27.5 MPa/km. This diagram suggests that the block within the viscous deformation regime (λ < 0.86) is less capable of withstanding pore fluid pressure than the matrix with vein-openings (λ > 0.97).

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