Fractures belonging to two different sets are shown in the Photographs below. Set 1 strikes at around N20E and dips between 15o and 30o toward SE (Photographs a and b); set 2 strikes at roughly N45W and has subvertical dips around 85o toward SW (Photographs a, c and d). The fracture surfaces of set 1 bear striae lineation parallel to the dip of the fractures, as shown in the sketch to the left of Photograph b. Besides the presence of vegetation and oxidation, the rock is weathered to some extent along set 1. A fracture of set 2 bears a plume feature on its oxidized surface ( Photographs c and d).

a) What are the fracture types, the tectonic regimes, and the orientation of the principal stresses that gave rise to each fracture set?

b) Is there indication of flow along any of the fractures? Explain your answer.

c) Describe and explain the potential flow paths, as well as the characteristics of the connected network, based on the Photographs and the presented data.

Photographs from Embu das Artes, São Paulo, Brazil, by Bruna Fiume

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