Exercise 9
The photograph below shows two fracture faces. One is vertical (N30W/90) and bears a plume, and the other has an intermediate dip (N76W/42SW).
Given this image, answer the following questions.
a) What type of fracture is the vertical fracture? What is the orientation of the principal stresses and the tectonic regime that produced it?
b) What is the mode of formation of the N76W/42SW fracture? What is the orientation of the principal stresses and the tectonic regime that generated it?
c) Is it possible that both fractures could have been formed in the same tectonic event (same stress field)? Explain your answer.
Photograph from Itapecerica da Serra, São Paulo, Brazil, by Amélia Fernandes