Page 99 - Microtectonics

4.2 · Foliations 87

Fig. 4.20. Discrete crenulation cleavage (S 2 subhorizontal) overprinting a slaty cleavage (S 1 trending from top left to bottom right). The crenu-
lation cleavage is defined by horizontal dark seams with wriggly to smooth appearance. The seams are interpreted as accumulations of
insoluble material along dissolution surfaces. Concepción, Chile. Width of view 1.8 mm. PPL

Fig. 4.21. Crenulation cleavage (S subvertical) overprinting a slaty cleavage (S ) that is parallel to bedding (S ). Development of the crenu-
1
o
2
lation cleavage was accompanied by solution effects. The extreme attenuation of the vertical fold limb in the quartz-rich (light-coloured)
layer coincides with the presence of accentuated dark seams along the S 2 plane in adjacent micaceous layers. Both are interpreted as the
result of preferred dissolution enhanced by the orientation of the fold limb, as explained in the text. This figure is a detail of Fig. 4.4.
Pyrenees, Spain. Width of view 5 mm. PPL