Geology Reference
In-Depth Information
the upper detachment, if any? Based on the results, is the structure locally balanced
or regionally balanced? Compute the layer parallel strains for each layer. Is the cross
section valid?
11.10.9
Predict Fault Geometry
The drape fold in horizons 1 and 2 in the South Hewett fault zone (Fig. 11.73) can be
explained by an underlying rotated block. Apply the circular-arc fault model to predict
the fault location and depth to detachment. The slip on some of the Zechstein normal
faults has been reversed in the later deformation. Does the model explain which faults
have reactivated?
11.10.10
Simple-Shear Restoration
Restore the growth normal fault in Fig. 11.74. This section contains growth stratigraphy
and can be sequentially restored to the regional for horizons 2 and 3 to show the growth
history. Why is the simple-shear method a reasonable choice? What is the appropriate
choice of the regional? What is the most appropriate shear angle and how do you find it?
Is the cross section valid?
11.10.11
Restoration and Prediction
Restore the cross section in Fig. 11.75 by either rigid-block displacement or flexural
slip. Discuss the reason for your choice of method. Predict the deep geometry of the
Schell Creek master fault using oblique simple shear. Find the shear angle from the
strain in the rollover.
Fig. 11.73.
The South Hewett fault zone in the North Sea. Interpreted and drawn from a seismic reflection
profile in Badley et al. (1989). Assume the vertical exaggeration is approximately 1 : 1. Horizon
1:
top Creta-
ceous Chalk;
2:
base-Cretaceous unconformity;
3:
top Zechstein;
TWT(S):
two-way travel time in seconds
