Figure 1a shows a simple case in which a shear band fault cuts and offsets a high-angle compaction band in sandstone. It is simple because both compaction band and shear band formed by strain localization into narrow bands albeit in different kinematics and at different times. Figure 1b shows a case which includes a shear band fault with a thrust sense of offset and a series of associated compaction bands in splay orientation. The compaction bands formed along bedding and this orientation is self consistent with the thrusting. Additional examples for this type of assemblages can be found in Mollema and Antonellimni (1996), and Du Bernard et al. (2002).

Figure 1. (a) A shear band (oblique in view) offsetting a high angle compaction band in the Aztec Sandstone, Valley of Fire state Park, NV. (b) A series of dilation bands associated with a shear band fault with thrust kinematics. (c) A shear band fault with thrust sense of offset and the associated splay compaction bands, many of which are bed-parallel and nearly horizontal. This structure and that in the next photo occur in unconsolidated terrace deposit exposed at a wave-cut cliff face at McKinleyville, northern California.

One can easily imagine that once rocks with deformation bands are deformed by jointing which is quite common in the field, the joints would provide weak planes to accommodate later shearing. The first example of this situation is from New York's Grand Central Park that we used for compaction bands and joint assemblages. Figure 2 shows two major sets of what appear to be compaction bands overprinted by two sets of joints and one fairly noticeable fault. Figure 3 shows a compaction band zone (thick white dashed lines) and two sets of related compaction band networks (thin solid white lines) overprinted by two sets of joints (blue) and a fault of about 25 cm left-lateral sense of apparent offset. It is reasonable to assume that similar to the case in Figure 2, a more prominent joint zone was later sheared to form the fault. Another example for this case is shown in Figure 4 in which a sheared joint fault overprinted one member of a compaction band set (measuring tape was placed on top of the compaction band-sheared joint pair). An interesting outcome of this juxtaposition is that a series of these splay joints associated with the shearing of the bounding first generation joint cuts across other members of the compaction band set at an oblique angle.

Figure 2. Two sets of deformation bands appear as lighter color tabular features with positive relief, some of which are overprinted by two sets of joints (red). One of these must have been sheared to some degree (blue line with arrows to show up-thrown and down-thrown blocks. From metasedimentary rocks cropping out at Grand Central Park, NY.

Figure 3. Two sets of compaction bands (thin white lines) and a zone of compaction bands (highlighted by thick dashed white lines) in the Aztec Sandstone cropping out at Valley of Fire State Park, Nevada. The compaction bands were overprinted by two sets of joints (blue lines). A zone of joints were sheared offsetting the compaction band zone by about 25 cm. Notice pen on the compaction band zone (near center of the frame) for scale.

Figure 4. A set of compaction bands (cb; up-down orientation) overprinted by a sheared joint (measuring tape on top of it), the splay joints of which cut other members of the compaction band set obliquely.