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Fig. 3 | Progress in Earth and Planetary Science

Fig. 3

From: Rheology and stress in subduction zones around the aseismic/seismic transition

Fig. 3

Structural and microstructural characteristics of the Pelona Schist. a Field photograph of thinly bedded metagreywacke with tight folds formed during return flow. This illustrates the intense ductile deformation characteristic of the schist. b Albite porphyroblasts formed at close to peak metamorphic conditions were pulled apart during return flow, and quartz was precipitated by pressure solution between them. The alternating bands of quartz and sheet silicates (white mica and chlorite) are a characteristic microstructure formed by pressure solution. c Quartz precipitated in pressure shadows around albite porphyroblasts in metagreywacke has an asymmetric shape indicative of top to the left (top NW) shear. The sample comes from the deepest part of the schist, and the microstructures represent the lower part of the subduction channel. d Asymmetric pressure shadows around albite porphyroblasts from the upper part of the subduction channel have an asymmetry indicating top SE shear sense

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