1. Briefly interpret the contact in red indicated by the arrows in the sketch at right. What kind of contact is this, and what are the relative age constraints on when it formed?
2. Briefly indicate the most likely interpretation of the red contact indicated by the arrows in the sketch at right. What kind of contact is this, and what are the constraints on when it formed?
The image at right is part of Grady Konzen’s structure contour map on the top “Big Injun” formation along the Ohio River east of Marietta. The reds represent higher elevations, the yellows and greens lower. Briefly describe and interpret this structure, including the type of fold illustrated, the type of fault illustrated, and the significance of the offset fold hingeline (i.e., is this a cutoff or a piercing point, and what is the significance of that distinction?)
please see all questions in the document. please show your work
Structural Geology
1. Briefly interpret the contact in red indicated by the
arrows in the sketch at right. What kind of contact is
this, and what are the relative age constraints on when
it formed?
Way Up
Miocene
Oligocene Eocene
Paleozoic metamorphic rock
2. Briefly indicate the most likely interpretation of the red
contact indicated by the arrows in the sketch at right.
What kind of contact is this, and what are the
constraints on when it formed?
Way
Up
Cenozoic strata
Paleozoic strata
3. The image at right is part of Grady
Konzen’s structure contour map on the
top “Big Injun” formation along the Ohio
River east of Marietta. The reds represent
higher elevations, the yellows and greens
lower. Briefly describe and interpret this
structure, including the type of fold
illustrated, the type of fault illustrated, and
the significance of the offset fold
hingeline (i.e., is this a cutoff or a piercing point, and what is the significance of that
distinction?)
4. What type of fault and what type of
fold are illustrated by the image at
right? Briefly describe the progressive
development of this fault-fold system.
5. What type of fault and what type of
fold are illustrated by the image at
right? Briefly describe the progressive
development of this fault-fold system.
6. The GoogleEarth view at right shows
the orientation of vertical joint
systems at Arches National Park in
Utah. What would have been the
orientation of the least principle
stress (3) at the time the joints
formed? Use arrows to draw and
label the orientation of 3 on the
image.
[Type here]
N
[Type2 here]
[Type here]
7. Compare and Contrast pure shear vs. simple shear deformation histories being careful to
address how material lines in various orientations rotate during the deformation history and
how the finite strain axes change with respect to the incremental strain axes.
8. Assuming the fracture systems illustrated at right all
formed under the same state of stress, name and
interpret the origin of the green vs. the blue joint
systems. Also, add and label arrows illustrating the
greatest and least principle stress orientations and
the expected resolved shear stresses on the conjugate
systems
9. What kind of sedimentary structure is illustrated in
this image, and what is the stratigraphic facing
direction (“way-up”) in this picture, and how do you
know?
[Type here]
[Type3 here]
[Type here]
10. Assuming the bedding in the image
above was turned on end by folding,
which of the sketches at right shows
the correct interpretation of the
geometry of the first-order fold?
Briefly describe how you figured it
out?
11. In the image at right, why is
cleavage in the sandstone steeper
than the cleavage in the slate, and
what is this phenomenon of
changing cleavage orientation
called?
12. The images at right shows two
alternative interpretations of the
first-order fold geometry from the
bedding-cleavage relationships in
the same sandstone-slate
sequence illustrated in the
previous question. Which
interpretation is correct and why?
13. Briefly describe the symmetry
and vergence direction of these
folds.
[Type here]
[Type4 here]
[Type here]
14. Based on the illustrated dip isogons, which Ramsey fold class do the folds illustrated at
right belong to, and how do you know?
15. Would the Ramsey fold class illustrated in the above be more likely to represent flexural
slip or passive flow folding? Explain.
16. Assume the thin, wavy black
lines represent parasitic fold
relationships in an outcrop.
Which of the two interpretations
illustrated would be more likely
to represent the first-order folds
in the vicinity of this outcrop?
Briefly explain how you figured
this out.
17. Briefly name, describe and
interpret the fold interference
pattern illustrated at right. Using
MS drafting tools, add and label
first and second generation fold
hingelines (3 pts)
18. Describe two different ways that original bedding (S0) could become transposed into a new
orientation.
[Type here]
[Type5 here]
[Type here]
19. Name the structure illustrated at
right and indicate the shear-sense
with shear-sense arrows.
20. The photomicrograph at right is a muscovite
bearing quartzite under crossed polars with
gypsum plate inserted. Use MS drafting tools to
label the S & C planes and shear-sense
direction on the photograph. Also, what is the
significance of the mica clasts? Briefly describe
the origin and significance of these structures
21. The figure at left is a quartz c-axis pole figure
from the same sample illustrated in question #32.
Use shear-sense arrows to indicate the sense of
shear based on the pole figure. Briefly explain
why crystallographic preferred orientations form
in deformed metamorphosed rocks.
[Type here]
[Type6 here]
[Type here]