Late Quaternary morphodynamics in the Quebrada de Purmamarca, NW Argentina

Abstract

Abstract. Ziel dieser Arbeit ist die Dokumentation geomorphologischer, sedimentärer und paläopedologischer Archive in der Quebrada de Purmamarca. Die Interpretation dieser Archive in Bezug auf die Paläoumweltbedingungen basiert hauptsächlich auf Feldforschungen und geomorphologischer Kartierung (May 2008). Einen Schwerpunkt dieser Studie bildet eine aus grobem Material aufgeschüttete Terrassenfolge. Während die Erosions- und Akkumulationsprozesse vermutlich auf das Zusammenspiel klimatischer und tektonischer Prozesse zurückzuführen sind, steht die Ablagerung der jüngsten ca. 150 m mächtigen Terrassenfläche wohl in Zusammenhang mit dem Absinken des periglazialen Einflussbereiches um mehr als 1000 m unter die heutige Höhenlage. Nach dem Ende der Terrassenschüttung, bieten vor allem Schwemmkegel, äolische Sande und gut entwickelte Paläoböden wertvolle Hinweise auf die durch Feuchtigkeitsveränderungen gesteuerte spätglaziale Landschaftsentwicklung. Die Hauptphase der Einschneidung datiert um einiges nach dem Ende der Terrassenaufschüttung und wurde vermutlich durch eine Zunahme der monsunalen Niederschläge gesteuert. Abschließend konnten die Auswirkungen kleinerer, vermutlich holozäner Schwankungen der Feuchtigkeitsverhältnisse über paläopedologische und geomorphologische Beobachtungen auf der Terrassenoberfläche und den Hängen beschrieben werden.

Landscape response to late Pleistocene climate change in NW Argentina: Sediment flux modulated by basin geometry and connectivity

“…S3, and Table S1-S3 Titles • Figure S1 • Figure S2 • Figure S3 In the western Central Andes, fill terrace formation has been commonly linked to wetter climate periods during the late Quaternary [e.g., Fontugne et al, 1999;Keefer et al, 2003;Magilligan and Goldstein, 2001;Nester et al, 2007;Magilligan et al, 2008;Steffen et al, 2009Steffen et al, , 2010Bekaddour et al, 2014]. In both the western and eastern Central Andes, fluvial aggradation has been explained as a result of increased hillslope erosion related to mass movements [Tchilinguirian and Pereyra, 2001;Steffen et al, 2009Steffen et al, , 2010Bekaddour et al, 2014] or an increase in periglacial weathering [May and Soler, 2010]. A recent study that links a series of large landslides in southern Peru to the "Ouki" wet climatic interval of ~120 to 100 ka [Margirier et al, 2015] supports the importance of sudden mass movements.…”

Late Quaternary Tectonics, Incision, and Landscape Evolution of the Calchaquí River Catchment, Eastern Cordillera, NW Argentina

“…Similar evidence for Quaternary incision is well documented in the Sierras Pampeanas and Santa Barbara System (González Bonorino & Abascal, ; Hilley & Strecker, ; Strecker et al, ). Pedogenesis is weak, and soils are dominated by carbonate (May & Soler, ; this study). Periglacial processes are restricted to areas over 4,500‐m elevation, but this limit may have been depressed by as much as 900 m during the Pleistocene, as evidenced by broad convex range crests and moraines in the Sierra de Quilmes and northwestern CRC (Haselton et al, ).…”

“…Interannual variability in precipitation is significant (±75%), and driven primarily by ENSO and the Tropical Atlantic Sea‐surface Temperature Variability (Trauth et al, ). Cooler and more humid periods occurred throughout the Quaternary (Bobst et al, ; Fritz et al, ), increasing landslide‐frequency (Trauth et al, ), expanding glacial (D'Arcy et al, ; Haselton et al, ) and periglacial (May & Soler, ) zones, and increasing overall catchment erosional efficiency (Bookhagen & Strecker, ). Glacial advances are linked to summer insolation when the South American Summer Monsoon is strongest, with local advances at ~44 ka in the Sierra de Quilmes (Zech et al, ) and ~40 ka in the Sierra Aconquija (D'Arcy et al, ).…”

Climatic controls on debris‐flow activity and sediment aggradation: The Del Medio fan, NW Argentina

“…The similarities between the modern deposits of the Del Medio catchment and the late Pleistocene fill terraces to the north [e.g., Tschilinguirian and Pereyra, 2001;Robinson et al, 2005;Rivelli and Flores, 2009;May and Soler, 2010] suggest that the Del Medio catchment may be a modern analog for processes that occurred upstream in the Humahuaca Basin in the past. First, like in the Del Medio catchment, mass movements and debris flows have been suggested to play a major role in the aggradation of the upstream fill terraces (Figure 10a), based on sedimentologic analyses [May and Soler, 2010], cosmogenic nuclide-derived denudation rates and grain-size dependencies [Schildgen et al, 2016], and stratigraphic-geomorphic relationships farther north [Tschilinguirian and Pereyra, 2001;Strecker et al, 2007;Streit et al, 2015]. Also, the work by Schildgen et al [2016] highlighted the apparent link between a change in climate (particularly a change to wetter conditions) with sediment aggradation.…”

“…Aggradation phases in this area, which today receives less than 200 mm of rainfall per year [ Bookhagen and Strecker , ], have been dated to between ~800 and 40 ka B.P. [ Tschilinguirian and Pereyra , ; Robinson et al ., ; Strecker et al ., ; Schildgen et al ., ] and have been linked to periods of increasing precipitation with an increased frequency of landslides and debris flows [ Tschilinguirian and Pereyra , ; May and Soler , ; Schildgen et al ., ]. Although these previous studies argued against tectonic controls on past aggradation, no explanations have been offered to explain the location of sediment aggradation with respect to climate‐related surface processes, and no attempts have been made to use modern aggradation patterns for providing insights into sediment dynamics in the Humahuaca Basin.…”