Comment on “Dynamic topography in South America” by Federico M. Dávila & Carolina Lithgow-Bertelloni

In their article Dávila and Lithgow-Bertelloni (2013) propose that the Andes have been isostatically uncompensated throughout the Cenozoic and that additional forces induced by mantle flow were required to explain the observed topographies. Although this hypothesis seems plausible, they provide a regional model of “the Bermejo-Pampas foreland of Argentina” which implies that the deposition of the Los Llanos Formation (in La Rioja, NW Argentina) occurred during Miocene. However, this age is incongruent with the presence of a neosauropod nesting site at Sanagasta and a Cretaceous faunal assemblage in Tama both in Los Llanos Formation and well documented in recent publications. Therefore, the proposed model for “the Bermejo-Pampas foreland of Argentina” appears incorrect. Moreover, the Cretaceous exposures at Sanagasta and Tama foster the need of revising the alleged Cenozoic age of the Los Llanos Formation in La Rioja and neighboring provinces, and the tectonic models associated with this formation.