GLY481/581 Study Questions Exam I

1. Development of major batholiths of the western cordillera reached its peak in the Jurassic and Cretaceous. A) Describe the main petrologic features of this batholith. B) What is the relationship of this batholith to the framework rocks to the east and to the west? C) Why was there a batholithic development so prominent at this time? D) What were the consequences of this batholith on the subsequent tectonic and geomorphic development of the cordillera?

2. In several ways, the Laramide Orogeny was distinct among the pulses of activity in the western cordillera. A) How is this orogeny unique in the foreland thrust belt? B) In what way is igneous activity peculiar in the Laramide orogeny? C) Why is the area affected by this orogeny so wide?

3. Describe the initial stages in the formation of the western cordillera preceding and during the time of the Antler Orogeny. Indicate the setting prior to the orogeny, the main events and consequences of the orogeny proper, and the geologic setting following this event. Place the discussion in chronological order.

4. Describe the three major tectonic elements of the western zone of the Late Jurassic to Late Cretaceous orogeny. Give the major features of each zone with their specific attributes.

5. What constitutes “accreted terrane? In the Jurassic to Cretaceous time several units of accreted terrane arrived at the margin of the western Cordillera. Describe this terrane is some detail citing the evidence that it is really accreted.

6. In a series of three E-W cross sections show the progressive stages in the accretion of the Franciscan terrane onto the North American plate starting with its existence as an island arc. Your cross sections should show the major tectonic units of Late Jurassic to Late Cretaceous time and the depth of the section should extend to about 150 km.

7. Draw an n E-W cross section across the eastern part of the Cordillera at the time of the time of the Laramide Orogeny. The line of the section will be indicated on a small map and will extend from the fold and thrust belt through the Rocky Mountain foreland. The section should extend to a depth of about 100 km. Label all of the major units involved in the deformation.

8. Define a few terms related to orogenesis.