Late Pleistocene and Holocene environmental and climatic conditions in the eastern Andean piedmont of Mendoza (33°–34°S, Argentina)

Mehl, Adriana Ester; Zárate, Marcelo

doi:10.1016/j.jsames.2012.01.003

Cited by 21 publications

(28 citation statements)

References 36 publications

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“…They occur in semiarid or arid regions worldwide (Prosser et al, 2001;Sancho et al, 2008;Mehl and Zárate, 2012;Boardman, 2014). Arroyo systems are inherently unstable, shifting at the century to millennial scale between an unincised aggradational state, in which fl oods are attenuated across a broad fl oodplain, and an incised state, in which fl oods, trapped within an oversized rectangular channel, have a higher unit stream power and are capable of net erosion.…”

Section: Arroyosmentioning

confidence: 99%

“…1) is initiated when the transport capacity, represented here by the channelaverage boundary shear stress, is increased relative to the load. This may result from (1) an increase in slope caused by base-level lowering (Schumm and Parker, 1973) or channel straightening (Simon, 1989), (2) an increase in runoff caused by intense rainfall or any factor that decreases upland vegetation cover, including drought or livestock grazing (Bryan, 1925;Osterkamp and Friedman, 2000;Prosser et al, 2001;Mehl and Zárate, 2012), (3) artifi cial channelization of the fl ow (Cooke and Reeves, 1976), (4) removal of vegetation on the channel boundary (Thornthwaite et al, 1942;Tucker et al, 2006), or (5) a decrease in the rate of sediment supply from upstream (Schumm and Hadley, 1957). After the fl ow is confi ned within the nascent arroyo, fl ow depth and shear stress during high fl ows are increased, resulting in further incision.…”

Section: Arroyosmentioning

confidence: 99%

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Processes of arroyo filling in northern New Mexico, USA

Friedman¹,

Vincent²,

Griffin³

et al. 2014

Geological Society of America Bulletin

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We documented arroyo evolution at the tree, trench, and arroyo scales along the lower Rio Puerco and Chaco Wash in northern New Mexico, USA. We excavated 29 buried living woody plants and used burial signatures in their annual rings to date stratigraphy in four trenches across the arroyos. Then, we reconstructed the history of arroyo evolution by combining trench data with arroyo-scale information from aerial imagery, light detection and ranging (LiDAR), longitudinal profi les, and repeat surveys of cross sections. Burial signatures in annual rings of salt cedar and willow dated sedimentary beds greater than 30 cm thick with annual precision. Along both arroyos, incision occurred until the 1930s in association with extreme high fl ows, and subsequent fi lling involved vegetation development, channel narrowing, increased sinuosity, and fi nally vertical aggradation. A strongly depositional sediment transport regime interacted with fl oodplain shrubs to produce a characteristic narrow, trapezoidal channel. The 55 km study reach along the Rio Puerco demonstrated upstream progression of arroyo widening and fi lling, but not of arroyo incision, channel narrowing, or fl oodplain vegetation development. We conclude that the occurrence of upstream progression within large basins like the Rio Puerco makes precise synchrony across basins impossible. Arroyo wall retreat is now mostly limited to locations where meanders impinge on the arroyo wall, forming hairpin bends, for which entry to and exit from the wall are stationary. Average annual sediment storage within the Rio Puerco study reach between 1955 and 2005 was 4.8 × 10 5 t/yr, 16% of the average annual suspended sediment yield, and 24% of the long-term bedrock denudation rate. At this rate, the arroyo would fi ll in 310 yr.

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Section: Arroyosmentioning

confidence: 99%

Section: Arroyosmentioning

confidence: 99%

Processes of arroyo filling in northern New Mexico, USA

Friedman¹,

Vincent²,

Griffin³

et al. 2014

Geological Society of America Bulletin

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“…() found terrace incision periods that correspond to each of these past warming events in the Diamante River area located 100 km south of Las Tunas. In the piedmont region of Tupungato, Mehl and Zárate () document a change from braided rivers from ca. 55 kyr to the early Holocene, to meandering rivers during the late Holocene.…”

Section: The Las Tunas Areamentioning

confidence: 99%

Pleistocene landscape entrenchment: a geomorphological mountain to foreland field case, the Las Tunas system, Argentina

et al. 2013

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The study of the Las Tunas River incisions, located in the eastern Andean foreland front (33∘20’ S in Argentina), provides new clues for the interpretation of deep piedmont entrenchments. Both the Las Tunas mountain catchment and its piedmont are strongly entrenched with maximal incision of over 100 m at the mountain front. Three main terrace levels are well exposed and are labelled T1, T2 and T3 from the youngest to the oldest. We combined geological and geomorphological field observations, kinematic GPS data, satellite data and aerial photos with geochronological 40Ar/39Ar and 10Be analysis to provide a detailed description of terrace organization and a discussion of the evolution of the Las Tunas landscape. The surprisingly constant 10Be concentrations in surface layers as deep as 1.5 m show that gently dipping alluvial surfaces can be continuously and deeply mixed. Our data show a first period of deposition (Mesones Fm) before 0.85 Myr (minimum T3 age), followed by deep erosion and a second sedimentation period (Las Tunas Fm) that includes a ca. 0.6 Myr ash deposit. T2 and T1 are inset in the Las Tunas Fm and were abandoned ca. 15–20 kyr ago. The similar ages for T2 and T1 show that post‐20 kyr entrenchment occurred very rapidly. Despite Quaternary deformation in the Las Tunas piedmont, terrace entrenchment is best explained by paleo‐climatic changes. The terrace organization reveals that the erosion‐sedimentation phases affected the entire system from the piedmont toe to 10 km upstream of the mountain front. Finally, contrary to the neighbouring more deeply incised Diamante River system, where late Quaternary piedmont uplift is more likely to have been a factor causing incision, the more stable Las Tunas system provides an incomplete geomorphological record of Pleistocene and Holocene climate variations. We suggest that climate variations are better recorded in uplifting piedmonts than in stable ones, where the magnitude of incision and sedimentation and the fact that they occur repeatedly at the same elevation can erase a large part of the record.

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“…This is also addressed in Tripaldi and Forman's (2007) study, which suggests a period of increased aridity generally matching the modern from 0e4 ka; this trend is also present in dune activity w200 km south of our study areas (Tripaldi et al, 2011) as discussed below, suggesting some similarities in climate over a broader region. Mehl and Zárate (2012) investigated the Quaternary alluvial record of piedmonts w200 km southwest of our study area, but did not attribute their findings to any specific climatic shifts.…”

Section: Regional Settingmentioning

confidence: 99%

Timing and nature of alluvial fan and strath terrace formation in the Eastern Precordillera of Argentina

Hedrick

Owen

Rockwell

et al. 2013

Quaternary Science Reviews

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Sixty-eight 10 Be terrestrial cosmogenic nuclide (TCN) surface exposure ages are presented to define the timing of alluvial fan and strath terrace formation in the hyper-arid San Juan region of the Argentine Precordillera. This region is tectonically active, and numerous fault scarps traverse Quaternary landforms. The three study sites, Marquesado strath complex, Loma Negra alluvial fan and Carpintería strath complex reveal a history of alluvial fan and strath terrace development over the past w225 ka. The Marquesado complex Q3 m surface dates to w17 AE 3 ka, whereas the Loma Negra Q1 ln , Q2 ln , Q3 ln , Q4 ln , and Q5 ln surfaces date to w24 AE 3 ka, w48 AE 2 ka, w65 AE 13 ka, w105 AE 21 ka, and w181 AE 29 ka, respectively. The Carpintería complex comprises eight surfaces that have been dated and include the Q1 c (w23 AE 3 ka), Q2 c (w5 AE 5 ka), Q3a c (w25 AE 12 ka), Q3b c (w29 AE 15 ka), Q4 c (w61 AE 12 ka), Q5 c (w98 AE 18 ka), Q6 c (w93 AE 18 ka), and Q7 c (w212 AE 37 ka). 10 Be TCN depth profile data for the Loma Negra alluvial fan complex and Carpintería strath terrace complex, as well as OSL ages on some Carpintería deposits, aid in refining surface ages for comparison with local and global climate proxies, and additionally offer insights into inheritance and erosion rate values for TCNs (w10 Â 10 4 10 Be atoms/g of SiO 2 and w5 m Ma À1 , respectively). Comparison with other alluvial fan studies in the region show that less dynamic and older preserved surfaces occur in the Carpintería and Loma Negra areas with only younger alluvial fan surfaces preserved both to the north and south. These data in combination with that of other studies illustrate broad regional agreement between alluvial fan and strath terrace ages, which suggests that climate is the dominant forcing agent in the timing of terrace formation in this region.

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Late Pleistocene and Holocene environmental and climatic conditions in the eastern Andean piedmont of Mendoza (33°–34°S, Argentina)

Cited by 21 publications

References 36 publications

Processes of arroyo filling in northern New Mexico, USA

Processes of arroyo filling in northern New Mexico, USA

Pleistocene landscape entrenchment: a geomorphological mountain to foreland field case, the Las Tunas system, Argentina

Timing and nature of alluvial fan and strath terrace formation in the Eastern Precordillera of Argentina

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