structural geology, propagation mechanics and - Stanford School of ...

dune boundary
dominant CB set
cross-bed boundary
secondary band set
dominant CB set
Figure 4.4. Example of mechanical interaction between compaction bands and æolian
sedimentary architecture in the Aztec sandstone (view is to the NW). Relatively parallel
compaction bands of the dominant, steeply E-dipping set are plainly visible at both the
top and bottom of the outcrop. At the fine-grained major dune boundary running
diagonally across the bottom half of the photo, bands of the dominant set either terminate
or warp into a drastically different WNW-dipping orientation with a more wavy outcrop
trace. At the upper cross-bed boundary, where the attitude of depostional bedding attitude
reverts to that at the bottom, the dominant band orientation, spacing and relatively
smooth outcrop trace resumes.
Thickness (mm)
14
12
10
8
6
4
2
0
0 6.25 12.5 18.75 25
Distance in meters from left tip
Figure 4.5. Tip-to-tip thickness profile for a 25-m-long, relatively straight (planar)
compaction band (black squares are measurements). The dark gray curve represents the
least-squares best fit of an ellipse to the data. The correlation index for this fit is 0.87, the
midpoint thickness is 9.5 mm (from Sternlof et al., 2005).
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