The principal oil basin of Peru, confined between the Andes and the Pacific Ocean, is a part of the long narrow belt (750×50 miles) of chiefly marine Tertiary sediments extending from northern Peru to western Colombia. Oil is produced on the Talara-Negritos, Lobitos, and El Alto uplifts from innumerable normal fault traps, which appear to have developed due to differences in basement density and/or rigidity rather than tectonic folding. The faults reflect the persistent tensional stress which prevailed from early Tertiary to early Quaternary. The area produces about 50,000 b/d of 37° gravity oil; cumulative production to date is about 600 million barrels.

The other oil-producing area of Peru is the heavily jungle-covered, scarcely explored Maranon Basin, which occupies the upper Amazon tributary drainage east of the Andes. This basin is a part of the sub-Andean trough, an elongate downwarp which persists from eastern Venezuela, through eastern Colombia, Ecuador, Peru, Bolivia, into western Argentina, lying between the overriding Andean uplift and the Guiana and Brazilian shields. The basin contains up to 12,000 feet of Tertiary and Quaternary fluviatile and lacustrine sediments which mask the Mesozoic and upper Paleozoic objectives. From outcrops and seepages in the Andean foothills, these objectives should constitute substantial reservoir and source rocks. The Ganso Azul and recently discovered Maquia fields, lying on the southwestern margin of the Maranon Basin in the belt of surface folds, are the only producing structures in the basin to date, with a daily production of less than 3,000 barrels, and an ultimate yield of probably less than 15 million barrels.

Attention is directed to the many geological similarities exhibited by North and South America in structural framework, tectonics, paleogeography, and stratigraphy.

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