Published 1995 as part of Memoir 62
Copyright © 1995 The American Association of Petroleum Geologists.  All Rights Reserved.

Seismic data, worldwide analogs, and surface geologic data show that the sub-Andean belt of northwestern Bolivia is a thin-skinned Dahlstromian fold and thrust belt with an estimated 150 km of Neogene bulk strain and 100 km of late Miocene-Pliocene bulk strain. The location adjacent to a suggested 70-km-deep Moho root and to a steep segment of the Peru-Chile subduction zone suggests that none of the mapped structures are thick-skinned foreland upthrusts. Based on consistent but inconclusive evidence, we distinguish an allochthonous complex transported above a Main sub-Andean thrust and a parautochthonous toe addition complex with three emerging frontal thrust sheets and several poorly constrained subthrust imbrications. The Main sub-Andean thrust unit had a blind front with an upper detachment that could have absorbed any amount of bulk strain.

Sub-Andean thrusting is explained as a response to two covariant forces. During the early-middle Tertiary, an asthenospheric wedge stacked the crust and the early sub-Andean structures. With the decay of the mantle wedge and the buoyant uplift of the Altiplano, plateau collapse gradually replaced the crustal stacking.