Drainage Reorganization Across the Puna Plateau Margin (NW Argentina): Implications for the Preservation of Orogenic Plateaus

Planform drainage reorganization is implicated in both the construction and destruction of elevated, low relief orogenic plateaus. The formation of internally drained basins and subsequent sediment infilling may enlarge plateaus, while more erosive rivers at plateau margins dissect these features. Assessing the contradictory role of planform drainage reorganization on the production, preservation, and dissection of orogenic plateaus requires understanding the potential controls on planform drainage changes. Given minimal evidence of major fluvial incision of the Puna Plateau, the Puna margin is an ideal location to elucidate the role of drainage reorganization on plateau preservation. Using local relief, channel elevations, normalized steepness channel index, and geomorphic evidence, we identify patterns of ongoing and paleodrainage reorganization across the Puna margin, and compare these results to potential tectonic, climatic, and lithologic controls. The majority of the modern Puna margin is stable and we find evidence of minor paleo‐divide migration into the plateau interior. We suggest tectonically controlled base level differences across the Puna margin pushed the divide into the plateau interior, until it stabilized at its modern position. However, we also find three examples of major, transient paleo‐divide migration back into the foreland controlled by basin geometry and rock erodibility (i.e., lithology and precipitation gradients) at the basin outlet. Our results emphasize the predominant role of widespread and recent tectonic base level changes and indirect structural controls on patterns of drainage reorganization and the formation and preservation of orogenic plateaus.