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Science Clinic => Geography => Topic started by: renzo156 on Feb 28, 2020

Title: The Laramide Rockies formed between about 85-50 million years ago. A popular theory is this event ...
Post by: renzo156 on Feb 28, 2020

Question 1

A region is characterized by numerous anticlines and synclines. There are also several faults present that appear to have formed at the same time as the folding. Without looking at any details, what type of faults would be most likely? Why?

Question 2

The Laramide Rockies formed between about 85-50 million years ago. A popular theory is this event was caused by "flat slab subduction" of over-thickened oceanic crust. From your understanding of mountain building processes in this part of the course, evaluate the following question(s).


Was this mountain building process an Andean type mountain building event, a collisional event, or both; and what might have been subducted to produce the over-thickened oceanic crust that drove the orogeny?

Title: The Laramide Rockies formed between about 85-50 million years ago. A popular theory is this event ...
Post by: tofugiraffe on Feb 28, 2020

Answer 1

Thrust faulting because thrust faults are associated with shortening as are most folds. A very astute student might also say normal faulting, which is also possible along curved normal faults, but less likely.

Answer 2

The mountain building process is a combination of the Andean and collisional processes; the mountains are basically subduction related, but the collision with a subductable thickened crust produced contraction of interior North America.