| Abstract: | The evolution of sea-floor spreading (directions and rates) in the Southeast Pacific, shows a close relationship with the Andean structural directions and the plutonic episodicity, as well as the succession of short compressive orogenic phases alternating with relatively longer periods of extension.The orogenic periods coincided with the beginning of periods of relatively higher rates of plate convergence, immediately after periods of relative “quiescence”, with the following periodicity: 110-85, 76-70, 63-60, 49-45, 35-33, 16-13, 7, m.y.The presence of oceanic structures as aseismic ridges or fracture zones produces “weak” Benioff zones (shallow and poorly defined), without a corresponding active volcanism. On the other hand, ancient continental structures such as the Precambrian-Paleozoic orogenic belts have active volcanism and neat, deep, and well developed Benioff zones. |
