Miocene to Quaternary basin evolution at the southeastern Andean Plateau (Puna) margin (ca. 24°S lat, Northwestern Argentina)

Abstract

The Andean Plateau of NW Argentina is a prominent example of a high-elevation orogenic plateau characterized by internal drainage, arid to hyper-arid climatic conditions and a compressional basin-and-range morphology comprising thick sedimentary basins. However, the development of the plateau as a geomorphic entity is not well understood. Enhanced orographic rainout along the eastern, windward plateau flank causes reduced fluvial run-off and thus subdued surface-process rates in the arid hinterland. Despite this, many Puna basins document a complex history of fluvial processes that have transformed the landscape from aggrading basins with coalescing alluvial fans to the formation of multiple fluvial terraces that are now abandoned. Here, we present data from the San Antonio de los Cobres (SAC) area, a sub-catchment of the Salinas Grandes Basin located on the eastern Puna Plateau bordering the externally drained Eastern Cordillera. Our data include: (a) new radiometric U-Pb zircon data from intercalated volcanic ash layers and detrital zircons from sedimentary key horizons; (b) sedimentary and geochemical provenance indicators; (c) river profile analysis; and (d) palaeo-landscape reconstruction to assess aggradation, incision and basin connectivity. Our results suggest that the eastern Puna margin evolved from a structurally controlled intermontane basin during the Middle Miocene, similar to intermontane basins in the Mio-Pliocene EasternCordillera and the broken Andean foreland. Our refined basin stratigraphy implies that sedimentation continued during the Late Mio-Pliocene and the Quaternary, after which the SAC area was subjected to basin incision and excavation of the sedimentary fill. Because this incision is unrelated to baselevel changes and tectonic processes, and is similar in timing to the onset of basin fill and excavation cycles of intermontane basins in the adjacent Eastern Cordillera, we suspect a regional climatic driver, triggered by the Mid-Pleistocene Climate Transition, caused the present-day morphology. Our observations suggest that lateral orogenic growth, aridification of orogenic interiors, and protracted plateau sedimentation are all part of a complex process chain necessary to establish and maintain geomorphic characteristics of orogenic plateaus in tectonically active mountain belts. 822 | EAGE PINGEL Et aL.

Development of an incipient Paleogene topography between the present‐day Eastern Andean Plateau (Puna) and the Eastern Cordillera, southern Central Andes, NW Argentina

“…In this context, Pingel et al. (2019) have suggested that the middle Miocene Los Patos Conglomerate (14.5 Ma, del Papa & Petrinovic, 2017) from the eastern margin of the Puna (at 24.2°S) formed as a result of topographic growth of the Eastern Cordillera, as this unit was deposited over a pronounced angular unconformity in deformed Paleogene units.…”

“…Other authors have, in contrast, suggested the existence of a broad, low‐elevation plain in the region of the present‐day Puna during the Paleogene that was interrupted by uplifts of isolated mountain ranges with generally subdued topography (e.g. Adelmann, 2001; Carrapa et al., 2005; DeCelles, Carrapa, & Gehrels, 2007; Pingel, Alonso, Altenberger, Cottle, & Strecker, 2019; Pingel et al., 2020).…”

Neogene Tectono‐Stratigraphic Evolution of the Intermontane Tarom Basin: Insights Into Basin Filling and Plateau Building Processes Along the Northern Margin of the Iranian Plateau (Arabia‐Eurasia Collision Zone)

“…Orogenic plateaus are vast and elevated morphotectonic features, which provide the unique opportunity to decipher the interplay between shallow, deep‐seated and surface processes, and their influences on Earth's landscape at various timescales (e.g., Dewey et al., 1988; Isacks, 1988; Molnar et al., 1993). They often contain internally drained basins that have coalesced and have been filled with thick sedimentary deposits and hence retain insights into orogenic, erosional and geodynamic processes (e.g., Alonso et al., 1990; Carroll et al., 2010; Horton et al., 2012; Meyer et al., 1998; Pingel et al., 2019a; Sobel et al., 2003; Strecker et al., 2009). One of the most accepted plateau‐building model predicts that reduced fluvial connectivity promotes basin filling with sediments, inhibits intrabasinal faulting, and triggers the outward propagation of the deformation fronts.…”

“…This includes basin excavation and erosion with the destruction of the typical plateau morphology (e.g., Heidarzadeh et al., 2017; Strecker et al., 2009). Therefore, while the sedimentary basins in the plateau interior are tectonically stable up to time scales of few 10 7 years (e.g., Alonso et al., 1990; Bush et al., 2016), intermontane basins at the transition with the foreland may experience a more complex evolution including several episodes of basin filling and plateau integration, fluvial incision and tectonic deformation at shorter time scales (10 5 to few 10 6 years; e.g., Ballato et al., 2019; Pingel et al., 2019a; T. Schildgen et al., 2016; Streit et al., 2015; Tofelde et al., 2017). Thus, these transitional basins hold precious information on the growth of the plateau margin, the evolution of adjacent mountain ranges, the sediment routing systems and the connectivity history among different sedimentary basins.…”

“…intermontane basins at the transition with the foreland may experience a more complex evolution including several episodes of basin filling and plateau integration, fluvial incision and tectonic deformation at shorter time scales (10 5 to few 10 6 years; e.g., Ballato et al, 2019;Pingel et al, 2019a;T. Schildgen et al, 2016;Streit et al, 2015;Tofelde et al, 2017).…”