Browsing by Author "Aravena, Juan Carlos"

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    Equilibrium line altitudes along the Andes during the Last millennium : paleoclimatic implications
    (2017) Sagredo T., Esteban; Lowell, Thomas V.; Kelly, Meredith A.; Rupper, Summer; Aravena, Juan Carlos; Ward, Dylan J.; Malone, Andrew G. O.
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    Holocene glacier history of northeastern Cordillera Darwin, southernmost South America (55°S)
    (2022) Reynhout, Scott A.; Kaplan, Michael R.; Sagredo T., Esteban; Aravena, Juan Carlos; Soteres García, Rodrigo León; Schwartz, Roseanne; Schaefer, Joerg M.Reynhout, Scott A.; Kaplan, Michael R.; Sagredo T., Esteban; Aravena, Juan Carlos; Soteres García, Rodrigo León; Schwartz, Roseanne; Schaefer, Joerg M.
    In the Cordillera Darwin, southernmost South America, we used 10Be and 14C dating, dendrochronology, and historical observations to reconstruct the glacial history of the Dalla Vedova valley from deglacial time to the present. After deglacial recession into northeastern Darwin and Dalla Vedova, by ~16 ka, evidence indicates a glacial advance at ~13 ka coeval with the Antarctic Cold Reversal. The next robustly dated glacial expansion occurred at 870 ± 60 calendar yr ago (approximately AD 1150), followed by less-extensive dendrochronologically constrained advances from shortly before AD 1836 to the mid-twentieth century. Our record is consistent with most studies within the Cordillera Darwin that show that the Holocene glacial maximum occurred during the last millennium. This pattern contrasts with the extensive early- and mid-Holocene glacier expansions farther north in Patagonia; furthermore, an advance at 870 ± 60 yr ago may suggest out-of-phase glacial advances occurred within the Cordillera Darwin relative to Patagonia. We speculate that a southward shift of westerlies and associated climate regimes toward the southernmost tip of the continent, about 900–800 yr ago, provides a mechanism by which some glaciers advanced in the Cordillera Darwin during what is generally considered a warm and dry period to the north in Patagonia.
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    Holocene tephrochronology around Cochrane (~47° S), southern Chile
    (2016) Stern, Charles R.; Moreno, Patricio I.; Henriquez, William I.; Villa Martinez, Rodrigo; Sagredo T., Esteban; Aravena, Juan Carlos; De Pol-Holz, Ricardo
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    Maximum expansion of the Tenerife Glacier (51°S) during the last millennium
    (2024) Amigo, Gonzalo; Aravena, Juan Carlos; Ruiz, Paulina; Kaplan, Michael; Sagredo, Esteban
    In the Patagonian Andes it is still under debate when the glaciers reached their maxi-mum expansion during the last millennium. In this work we analyze the fluctuations of Tenerife Glacier (51 degrees), a small mountain glacier located immediately to the south of the Patagonian Ice Fields. A detailed analysis of the glacial landforms of the valley allowed us to identify three moraine systems, in the south-central, southwestern, and northern parts of the Monte Tenerife valley, respectively. Based on ages obtained by count tree rings (Nothofagus pumilio) and Placopsis cf. gelida (L.) Linds lichens diameter measure-ments, we estimated that the Tenerife Glacier receded from its maximum extent in the last thousand years immediately after 1742-1765 AD. The maximum expansion of the Tenerife Glacier during the last millennium coincides with the maximum expansions of the Schiaparelli (54 degrees S) and Stoppani (55 degrees S) glaciers. However, other glaciers reached their glacial maximum limit earlier and show temporal asynchrony in when they reached their largest extents. This suggests a temporal variability in the glacial maximum during the last millennium in southern Patagonia (49 degrees and 55 degrees S)