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

Figure 1.7. (opposite page) Compaction band orientation data from the Valley of Fire.
Stereograms are lower hemispheric equal area projections of normals to the CB planes;
lines to the central air photo (same as in Figure 1.1) indicate the approximate location
where each set of data was collected; capital letter designations for each plot reflect the
order of collection. Three distinct orientation groupings are apparent, although only five
locations (C, B, F, L and O) exhibit more than one (see Figure 1.8). Relevant structural
data from Figure 1.1 (Overton syncline [OS], northern tip of Baseline fault [BF] and
Cretaceous bedding orientations) are as indicated. Stereogram X is from the location
marked with a circled X in Figure 1.4, an area of Aztec outcrops called Buffington
Pockets that comprise a window through the Paleozoics of the overriding Muddy
Mountain thrust.
P
n = 22
B
S
dihedral angle
P to S = 80.5
P
n = 29
C
S
T
dihedral angles
o
P to S = 80.0
o
P to T = 32.7
o
S to T = 80.0
P?
n = 18
F
S
T
dihedral angles
o
P to S = 83.1
o
P to T = 7.5
o
S to T = 83.6
P
n = 23
L
S
dihedral angle
o
P to S = 75.9
P
n = 30
O
S
T
dihedral angle
P to S = 87.7
o o
Figure 1.8. Angular relationships between compaction band sets at the five outcrop
locations exhibiting multiple orientations (see Figure 1.7). P = primary set in terms of
park-wide abundance, S = secondary set, T = tertiary set. Dihedral angles were computed
between the mean orientations for each band set. Sets P and S are at high dihedral angle
to each other at all locations, as are sets S and T. Sets P and T, however, are at variably
low dihedral angle.
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