Fold growth and lateral linkage in the southern Sub-andean fold-and-thrust belt of Argentina and Bolivia

The Argentinean and Bolivian sub-Andean fold-and-thrust belt is located in the orogenic front between 18-23 degrees S and 64-63 degrees W and immediately to the east of the Puna-Altiplano system and Eastern Cordillera. This fold-and-thrust belt is characterized by thin-skinned structures detached in Lower Paleozoic sequences. The compressional stage that affected this part of the orogen began in late Miocene and is ongoing. Examining the morphology of the folds and thrusts by combining digital elevation models, geological maps, and field observations allows us to present tectonic and geomorphological data on lateral fold growth and spatially linked shortening along the San Antonio range. The crest of this fold chain shows multiple culminations, slightly right-stepping, that merge to form the full San Antonio structural trend. Forked drainage patterns and the presence of wind gaps suggest recent fold amplification and lateral growth from these culminations. Linear and stepped linkage geometries are found between single structures. A northward increase in surface elevation and fluvial erosion follows the south to north increase in fold amplitude, aspect ratio, and change in structural style from folding to thrusting. The observed along-strike alternation of topographic highs and lows correlates well with the locations of subsurface hydrocarbon traps and saddle spill points indicating that the shallow and deep deformation patterns are coupled as a single structural feature.