Block III is located in the Talara basin in northern Peru. The block contains the Portachuelo, La Brea, Mirador, Boca, Lagunitas, La Isla and South Mirador oil fields. Block III lies on the southern flank of the Talara basin. The basin has experienced extensional tectonic movements that created deep depocenters, with remarkable tectono-sedimentary episodes. Finer-grained sediments accumulated in oxygen deficient sectors that contain oil-prone organic shales. Clastic reservoirs for oil and gas are relatively "mature" and free of substantial amounts of volcanic rock fragments.