Geology Reference
In-Depth Information
a heavy liquid is spilled in the stream valley in the shaded area, could the fault provide a
barrier to the fluid movement in porous units above the shale marker? Explain the reason
behind your answer. Where would a fault trap for fluids lighter than water be located?
8.8.7
Faults on an Isopach Map
Figure 8.55 is an isopach map. Locate the faults that explain the thickness changes.
Indicate the upthrown and downthrown sides of each fault. Determine the throw on
each fault. Make a structure contour map of the faults.
8.8.8
Cutoff Map of Normal Fault
Construct a fault cutoff map for the northern fault on the structure contour map in
Fig. 8.56. Project the cutoff lines to the blank profile below the map.
8.8.9
Cutoff Map of Reverse Fault
Construct a fault cutoff map for fault A across the structure contour map in Fig. 8.57.
8.8.10
Fluid Migration across a Fault
Suppose a toxic liquid that is heavier than water is spilled onto the surface in the center
of the structure illustrated by the Allan diagram in Fig. 8.58. Where will the liquid go?
Will the liquid be trapped at a location on the cross section? If liquid is trapped, will
it all be in the same location?
8.8.11
Thrust-Faulted Fold
Based on the map in Fig. 3.29, answer the following questions. What is the 3-point dip of
the fault at the surface? Construct a structure contour map of the fault from its surface
dip. Intersect the previously-constructed structure contour map of the top Fairholme
(Exercise 7.7.4) with the map of the fault. Does the projected structure contour map agree
with the drilled depths to the top of the Fairholme?
8.8.12
Relay Zone
Map the faults and the top of the Northriver Sandstone on the map of Fig. 8.59. Where
is the relay zone? What is the attitude of the sandstone away from the faults? What is
the attitude of the sandstone between the faults? What are the attitudes of the faults?
What is the maximum throw and heave on the faults?
