How to distinguish object-related and Andersonian flanking folds

Object related flanking folds will normally show no slip, unless they intruded as veins along older faults (Movie 1, Fig. 4). Also, a certain volume of material of a rheology different from that of the wall rock must be present. If flanking folds are induced by alteration rims, they can normally be spotted since the alteration rims will vary in thickness or be locally absent; flanking folds will then be bound to the sites with alteration only (Fig. 4).

Andersonian flanking folds are normally associated with slip, and reverse slip is quite typical (Movies 2-4; figs 5-7). Faults may be sealed with vein material (Fig. 6, 7), but can also remain free of deposits. Typically, gradients in the geometry of flanking folds are smooth and flanking folds are present along the entire length of the CE. Where faults open in extension, foliation boudins can form with larger veins filled with blocky and idiomorphic crystalline vein material (Arslan et al. 2008).