Late cenozoic structural and tectonic development of the western margin of the central andean plateau in southwest Peru

Structural and thermochronologic studies of the western margin of the central Andean Plateau show changing styles of deformation through time that give insights into tectonic evolution. In southwest Peru, uplift of the plateau proceeded in several distinct phases. First, NW striking, NE dipping reverse faults accommodated uplift prior to ∼ 14-16 Ma. Subsequent uplift of the plateau relative to the piedmont (between the plateau and the Pacific Ocean) occurred between ∼ 14 and 2.2 Ma and was accommodated by NW striking, SW dipping normal faults and subparallel monoclinal folds. The youngest phase of uplift affected the piedmont region and the plateau margin as a coherent block. Although the uplift magnitude associated with phase 1 is unknown, phases 2 and 3 resulted in at least 2.4-3.0 km of uplift. Up to 1 km of this may have occurred during phase 3. Geodynamic processes occurring in both the continental interior and the subduction zone likely contributed to uplift.