Figure 10
Structural characteristics of crystals and crystal assemblies on the two sides of the POS in Pulleniatina obliquiloculata shells. (a) EBSD band contrast measurement, with the distribution of 60° grain boundaries superimposed as red lines. (b) and (e) crystal orientation maps and (d) and (f) corresponding pole figures. Illustration of structural characteristics of the crystals and crystal units on the two sides of the POS: (1) fibril to platy crystal assemblages that are twinned (b) and (2) blocky, crystals that are not twinned (e). Blocky and fibril/fibrous-platy crystal assemblies have similar preferred orientation texture (d, f), they are, however, different in microstructure and crystal co-orientation strength. The blocky crystals are slightly less well co-oriented compared to the fibrous/platy crystals. Calcite c-axes are perpendicular to the shell surface for both the blocky as well as the fibril/platy crystal assemblages (white and black arrows in (b), (d), (e), (f)).
