A bonus attraction for structural geologists visiting Rio is the gneisses and sheared granitic rocks that crop out several places within and near the city.
Nice garnetiferous (kinzigitic) gneisses crop out at the E end of Ipanema (Leblon). These rocks must have seen considerable pressures and temperatures, perhaps someone can tell me more about this.
A relatively safe place to combine the beach and structural geology is the point between Ipanema and Copacabana. I stopped at the southern part of this point and found some very pretty S-C structures in the sheared granite indicating sinistral shear. Well worth seeing!
Enclaves (xenoliths) occur locally that at least vaguely suggest the amount of strain that these rocks have enjoyed.
The granitic rocks are Neoproterozoic and, according to the information I have, pre- to syn-collisional with respect to the orogeny that took place when Gondwana formed, in this particular area some 570 Ma.