Solution Exercise 13
The same direction and high dips toward opposite senses are typical characteristics of conjugate fractures formed in the extensional regime; both the acute angle between the veins (around 10°), and the infilling of the fractures indicate that these are conjugate hybrid fractures simultaneously propagated by opening and shear. In this tectonic regime, σ1 is vertical and σ3 is horizontal and perpendicular to the direction of the conjugate fractures. In this case, the direction of σ3 is N20W.
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