Along-strike structural variations in the Southern Patagonian Andes: Insights from physical modeling

The Southern Patagonian Andes between 48° and 53° SL offers a unique opportunity to study the results of orogenic growth superimposed over a previously rifted region. In this sector the northern Austral or Magallanes basin was affected by late to middle Jurassic extension followed by Late Cretaceous to Neogene tectonic compression. The resultant fold-thrust belt displays significant along-strike variations in width and lateral position of the structural domains that may be reflecting a first order control of the Jurassic extensional depocenters, as proposed in previous works. This hypothesis is tested using a series of scaled sandbox analog models involving the positive inversion of two adjacent depocenters with different extensional rates accommodated by a transfer fault. The correlation between structures in the Southern Patagonian Andes and the features in the model have important first order similarities supporting the theory of a positively inverted extensional basin with a previous history of southward increase in extension. Moreover structural cross-sections analyzed from field and seismic data have a geometry that is consistent with serial cross sections resulting from the models. ► A series of sandbox experiments simulate the tectonic evolution of the Southern Patagonian Andes. ► The experiments involved the positive inversion of two depocenters with differential stretching. ► Strong lateral structural variations are associated with experimental transfer zones. ► Results are in concordance with similar features from field and seismic data.