Palynological evidence of the geoecological belts dynamics from Eastern Cordillera of NW Argentina (23° S) during the Pre-Last Glacial Maximum

Torres, Gonzalo Román; Lupo, Liliana Concepción; Kulemeyer, Julio José; Pérez, Claudio F.

doi:10.5027/andgeov43n2-a01

Cited by 9 publications

(8 citation statements)

References 35 publications

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“…En el modelo presentado en este trabajo, Nothofagus está presente con porcentajes polínicos totales de entre 40 a 60% en áreas desprovistas de bosque, e incluso cientos de metros por encima de la línea de bosque. La depositación de polen a larga distancia de este tipo de taxones arbóreos, influenciada por corrientes de ladera de ascenso o descenso o a partir de áreas fuente a kilómetros de distancia, ha sido advertida a partir de investigaciones previas en la Patagonia norte y en el norte de Argentina (e.g., Pérez et al, 2009;Torres et al, 2016). Por otro lado, Páez et al (2001) y Markgraf et al (2003) señalaron que en la Patagonia, el polen arbóreo (principalmente Nothofagus y Cupressaceae) podía representar hasta el 30% en muestras de superficie en áreas de vegetación de estepa, lo que evidencia la importancia del transporte de larga distancia.…”

Section: Nuevos Aportes Al Entendimiento De La Representación Polínica De Los Ecosistemas Andino-patagónicosunclassified

Dinámica de la vegetación andina del lago Argentino (50° S, 72° O) desde el retiro de los glaciares (ca. 12.000 años cal AP)

Sottile

Echeverria

Tonello

et al. 2020

andgeo

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Paleoecological studies in Patagonia provide information about vegetation and climate changes occurred during the Holocene. The climatic evolution of this region offers a unique opportunity to study the environmental variability as well as the ecosystem variations. The dynamic of the forest ecosystems is modulated by the occurrence of disturbances. Fires are one of the most important disturbances in temperate forest ecosystems, and its study allows contrasting independently about the changes experienced by ecosystems. In addition, in Patagonia, environmental and postglacial vegetation changes have been determined by variations in the temperature and westerlies winds. In order to reconstruct changes experienced by the forest ecosystem and patterns of plant diversity during the Holocene, in relation to Postglacial dynamics, natural and anthropic disturbances in the Lake Argentino, pollen and charcoal were studied in a sedimentary sequence at Península Avellaneda. Pollen assemblages suggest non-cyclic changes in plant diversity during the Holocene. The highly diverse cold grass-shrub communities dominated the area up to the Early Holocene, when they were displaced upland by less diverse forest and steppes. Also, The Early and Midd-Holocene was characterized by opposite variations of hydric balance between Andean and extra-andean plant communities present between 48° and 50° S, whereas fire activity occurs synchronously between forest (Andean) and steppe communities (Extra-andean). Late Holocene is characterized by different proxy signals depending on the geographical location of the paleoecological records. To conclude, this work provides a better understanding of the fossil pollen record by its comparison with modern surface pollen samples along an altitudinal vegetation gradient.

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Section: Nuevos Aportes Al Entendimiento De La Representación Polínica De Los Ecosistemas Andino-patagónicosunclassified

Dinámica de la vegetación andina del lago Argentino (50° S, 72° O) desde el retiro de los glaciares (ca. 12.000 años cal AP)

Sottile

Echeverria

Tonello

et al. 2020

andgeo

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“…However, during the past several tens of thousands of years, the Central Andes experienced glacial advances during cooler and wetter episodes associated with orbital cycles and millennial-scale climate events (Smith et al, 2005a,b;Jomelli et al, 2014;Bromley et al, 2016;Martini et al, 2017;Ward et al, 2017). These climate changes have been reconstructed using archives and proxies including lake cores and shorelines (Sylvestre et al, 1999;Baker et al, 2001;Placzek et al, 2006Placzek et al, , 2013Baker and Fritz, 2015), plant fossils and pollen (Chepstow-Lusty et al, 2005;Maldonado et al, 2005;Torres et al, 2016), stable isotopes (Cruz et al, 2005;Wang et al, 2007;Kanner et al, 2012), ice cores (Thompson et al, 1995(Thompson et al, , 1998Ramirez et al, 2003), biomarkers (Fornace et al, 2016), and basin sediments (Nester et al, 2007;Steffen et al, 2009Steffen et al, , 2010Bekaddour et al, 2014;Schildgen et al, 2016;Tofelde et al, 2017). Moraines also provide valuable site-specific records of cooler and wetter conditions, and can be dated to constrain the timings of past glacial advances (Tapia, 1925;Rohmeder, 1941).…”

Section: Introductionmentioning

confidence: 99%

Timing of past glaciation at the Sierra de Aconquija, northwestern Argentina, and throughout the Central Andes

D’Arcy

Schildgen

Strecker

et al. 2019

Quaternary Science Reviews

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Advances in cosmogenic nuclide exposure dating have made moraines valuable terrestrial recorders of palaeoclimate. A growing number of moraine chronologies reported from the Central Andes show that tropical glaciers responded sensitively to past changes in precipitation and temperature over timescales ranging from 10 3 to 10 5 years. However, the causes of past glaciation in the Central Andes remain uncertain. Explanations have invoked insolation-modulated variability in the strength of the South American Summer Monsoon, teleconnections with the North Atlantic Ocean, and/or cooling in the Southern Hemisphere.The driver for these past climate changes is difficult to identify, partly due to a lack of dated moraine records, especially in climatically sensitive areas of the southern Central Andes.Moreover, new constraints are needed on precisely where and when glaciers advanced. We use cosmogenic 10 Be produced in situ to determine exposure ages for three generations of moraines at the Sierra de Aconquija, situated at 27°S on the eastern flank of the southern Central Andes. These moraines record glacier advances at approximately 22 ka and 40 ka, coincident with summer insolation maxima in the sub-tropics of the Southern Hemisphere, as well as at 12.5 ka and 13.5 ka during the Younger Dryas and the Antarctic Cold Reversal, respectively. We also identify minor glaciation during Bond Event 5, also known as the 8.2 ka event. These moraines register past climate changes with high fidelity, and currently constitute the southernmost dated record of glaciation on the eastern flank of the Central Andes. To contextualise these results, we compile 10 Be data reported from 144 moraines in the eastern Central Andes that represent past glacier advances. We re-calculate exposure ages from these data using an updated reference production rate, and we re-interpret the moraine ages by taking the oldest clustered boulder age (after the exclusion of outliers attributed to nuclide inheritance) as closest to the timing of glacier advance-an approach for which we provide empirical justification. This compilation reveals that Central Andean glaciers have responded to changes in temperature and precipitation. We identify cross-latitude advances in phase with insolation cycles, the last global glacial maximum, and episodes of strengthened monsoonal moisture transport including the Younger Dryas and Heinrich Stadials 1 and 2. Our results from the Sierra de Aconquija allow us to constrain the southerly limit of enhanced precipitation associated with Heinrich Stadials at ~25°S. More broadly, our findings demonstrate at both local and regional scales that moraines record past climate variability with a fine spatial and temporal resolution.3

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“…When the lake experiences a regression (Fig. 9B), the coastal zones increase in surface area and become more humid, generating favorable conditions for the development of herbaceous vegetation and correspondingly, the appearance of colonizing species such as ferns (Torres et al, 2016;Williams et al, 2011), ultimately generating a greater amount of spores. In addition, the shore is closer to the core, so it will have a higher concentration of pollen grain and spore.…”

Section: Palynological Interpretationmentioning

confidence: 99%

Paleoenvironmental reconstruction of the semi-arid Chaco region of Argentina based on multiproxy lake records over the last six hundred years

Speranza

Giralt

Lupo

et al. 2019

Palaeogeography, Palaeoclimatology, Palaeoecology

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In this paper, we analyze the paleoclimatic and paleoenvironmental evolution of Laguna Yema in semi-arid Chaco region of Argentina over the past six hundred years. High resolution multiproxy studies of lake sediments utilize analyses of lithology, mineralogy, geochemistry, palynology, and are constrained by radiocarbon and gamma spectrometry dating. Laguna Yema sediments were mainly composed of well stratified fine sediments (silts and clays), with variable proportions of quartz, clays (illite) and feldspar (microcline and albite). Twelve light and heavy geochemical elements were registered. Most elements (Al, Si, K, Ti, Fe, Rb, Ba, and Br) are associated with illite and albite. Different material transport processes related to the changes in aridity and humidity of the basin were identified using the main mineralogical origins of geochemical elements.Palynological records indicate cycles of contraction and expansion of the lake, with an increase in concentration of Alternanthera aquatica during wet periods (expansion of lake), and an increase in Ambrosia, Poaceae and fern spores during dry periods (contraction of lake). These changes are linked to fluctuations in moisture conditions in the Subandean Mountains and semi-arid Chaco regions, in response to interactions between the South American Monsoon System (SAMS) and the South American Low Level Jet (SALLJ), which send warm and humid air to northern Argentina. In a regional context, the Laguna Yema records are in accordance with the analyses of the temporal and spatial pattern of moisture distribution for the last six centuries.

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Palynological evidence of the geoecological belts dynamics from Eastern Cordillera of NW Argentina (23° S) during the Pre-Last Glacial Maximum

Cited by 9 publications

References 35 publications

Dinámica de la vegetación andina del lago Argentino (50° S, 72° O) desde el retiro de los glaciares (ca. 12.000 años cal AP)

Dinámica de la vegetación andina del lago Argentino (50° S, 72° O) desde el retiro de los glaciares (ca. 12.000 años cal AP)

Timing of past glaciation at the Sierra de Aconquija, northwestern Argentina, and throughout the Central Andes

Paleoenvironmental reconstruction of the semi-arid Chaco region of Argentina based on multiproxy lake records over the last six hundred years

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