Quaternary alluvial terraces in an active tectonic region: the San Juan River Valley, Andean Ranges, San Juan Province, Argentina

Geomorphological evolution of the Tilcara alluvial fan (Jujuy Province, NW Argentina): Tectonic implications and palaeoenvironmental considerations

“…Sancho et al (2004) (Fornari et al, 2001), and the relatively mild and humid conditions of a Last Glaciation Interstadial period, between 60 and 30 ka, which has been identified in several Andean areas (Rabassa and Clapperton, 1990). Under these arid conditions, the Tilcara fan sedimentary dynamics could be controlled by ephemeral stream flows, whose high effectiveness of sediment transport was due to large water discharges (Colombo et al 2000), and probably related to heavy rainfall associated with El Niño events occurring throughout the Late Pleistocene. At a regional scale in the Andes an evident relationship between historical alluvial fan activity and ENSO has been observed (Vargas et al, 2000;Keefer et al, 2003;Hartley et al, 2005;Colombo, 2005b).…”

“…Their occurrence is related to the scarps defining the Quebrada and is associated with the sedimentary activity of the Río Grande tributary network under arid environmental conditions and in an active compressive tectonic context. Inside the Quebrada de Humahuaca several patterns of alluvial fan evolution (Bull, 1977;Silva et al, 1992;Harvey, 1997;Colombo et al, 2000) can be differentiated based on their morphostratigraphic features. Although the present-day alluvial fan activity, affecting routes, railways and villages, has been analysed by Chayle and Wayne (1995), Solís and Orozco (1996), very few detailed studies concerning geomorphological, sedimentological and chronological aspects of these Quaternary morphosedimentary units have been carried out (Azarevich et al, 1999).…”

“…In arid regions with active tectonics, dating of alluvial fans is necessary to elucidate the palaeoclimatic meaning of the alluvial fan development and to quantify the tectonic activity (Siame et al, 1997). From a regional point of view, there are interesting contributions on Quaternary alluvial fans conducted by Colombo et al, 1996Colombo et al, , 2000Siame et al (1997) and Colombo (2005aColombo ( , 2005b, in different areas of the San Juan Province, and by Colombo (2005aColombo ( , 2005b, at several locations within the Salta and Mendoza provinces, which may be used for comparison. In addition, Robinson et al (2005) have applied luminescence techniques to date several deposits within Late Pleistocene alluvial fan sequences, in Jujuy and Salta provinces, reporting an age from the Tilcara alluvial fan.…”

Pedosedimentary development of part of a Late Quaternary loess‐palaeosol sequence in northwest Argentina

“…Bearing in mind its location within the Sierras Pampeanas, a region of active faulting in the late Cenozoic including intense seismicity in the Holocene (Ramos et al, 2002), it is feasible that such erosion may have been induced by episodic uplift. Although no data are available from the immediate vicinity of Tafí del Valle, river terraces arising from incision of the Rio San Juan into Tertiary bedrock (San Juan Province: 31 S, 69 W, about 500 km southwest of the Tafí basin) have been used to suggest high rates of recent tectonic uplift and a resultant mean exhumation rate for the past 43 kyr of 0.9-1.0 mm yr À1 (Colombo et al, 2000). Alternatively, the period(s) of truncation might correspond to identified regional phases of extensive erosion (ca.…”

El modelo periglacial de los abanicos aluviales telescópicos: análisis en dos cuencas precordilleranas (31º 51’ S y 68º 28’ W)

“…Las cuencas alimentadas en el ambiente precordillerano, depositaron en sus partes distales al alcanzar el río San Juan, de alimentación cordillerana, distintos niveles de abanicos que fi nalmente son terrazas, por lo cual los autores los citamos como abanicos-terrazas que conforman un AAL. Colombo et al (2000) y Colombo (2005), estudian terrazas cuaternarias del río San Juan y en particular tres cuencas ubicadas varios km al este de la zona en estudio, correspondiente a la de los ríos Sasso, Sassito y Albarracín, todos afl uentes del río San Juan. Este autor señala que los segmentos más modernos se ubican cada vez en una posición topográfi ca inferior.…”