Abstract

Apatite and zircon fission-track cooling ages constrain the Tertiary cooling and uplift history of the eastern Cordillera and Altiplano of Bolivia. Fission-track data are from two Triassic plutons and surrounding Paleozoic metasedimentary rocks in the eastern Andes north of La Paz. Zircon cooling ages indicate that the roof of the Huayna Potosi pluton was emplaced in the zircon partial annealing zone and that the Zongo pluton was emplaced entirely in the zircon total annealing zone. Apatite cooling ages for both plutons record uplift in the past 5–15 m.y., and zircon cooling ages from the Zongo pluton reflect uplift in the past 25–45 m.y. Uplift rates calculated by these apatite and zircon cooling ages suggest that uplift rates were 0.1–0.2 mm/yr between 20 and 40 Ma and increased significantly between 10 and 15 Ma. By 3 Ma, uplift rates may have been as high as 0.7 mm/yr.

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