Browsing by Author "Fernandez-Navarro, Hans"

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    Current understanding, knowledge gaps, and challenges of mountain permafrost research in the Chilean and Argentinean Andes
    (2024) Fernandez-Navarro, Hans; Baldis, Carla Tapia; Rojas, Claudia; Derrien, Morgane; Villasenor, Tania
    Mountain permafrost extends over a vast area throughout the Chilean and Argentinean Andes, making it a key component of these mountain ecosystems. To develop an overview of the current state of knowledge on southern Andean permafrost, it is essential to outline appropriate research strategies in a warmer climate context. Based on a comprehensive review of existing literature, this work identifies eight main research themes on mountain permafrost in the Chilean and Argentinean Andes: paleoenvironmental reconstructions, permafrost-derived landforms inventories, permafrost distribution models, internal structure analysis, hydrogeochemistry, permafrost dynamics, geological hazards, and transitional landscape studies. This extensive review work also highlights key debates concerning the potential of permafrost as a water resource and the factors influencing its distribution. Furthermore, we identified several challenges the scientific community must address to gain a deeper understanding of mountain permafrost dynamics. Among these challenges, we suggest tackling the need to broaden spatial focus, along with the use of emerging technologies and methodologies. Additionally, we emphasize the importance of developing interdisciplinary approaches to effectively identify the impacts of climate change on mountain permafrost. Such efforts are essential for adequately preparing scientists, institutional entities, and society to address future scenarios.
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    Fluctuations of the Universidad Glacier in the Andes of central Chile (34? S) during the latest Holocene derived from a 10Be moraine chronology
    (2023) Fernandez-Navarro, Hans; Garcia, Juan-Luis; Nussbaumer, Samuel U.; Tikhomirov, Dmitry; Perez, Francia; Gartner-Roer, Isabelle; Christl, Marcus; Egli, Markus
    The reconstruction of glacier fluctuations during the latest Holocene (<1000 years) is necessary for understanding the climate context preceding the warmer conditions of the 20th and 21st centuries. The glacier records in the Andes of central Chile are suitably located to track former latitudinal changes of the Southern Westerly Winds (SSW), which are mostly unknown at this middle latitude region. Here, we present a reconstruction of the glacial fluctuations using Terrestrial Cosmogenic Nuclides (10Be) dating of boulders resting on moraines and other glacial landforms that make up the moraine complex in the forefield of the Universidad Glacier (34 degrees S). This massive and chaotic-looking moraine was built during the latest Holocene ice advances and subsequent decay of the Universidad Glacier to its present position. Geomorphological mapping and 10Be surface exposure ages (n = 20) show that the Universidad Glacier advanced at least twice to nearly the same maximum extent, first by the 13th to 16th centuries and then by the early to the mid-19th century. Since then, eight moraine ridges denote a rather active and gradual ice demise. We interpret the glacier advances as a response to an equatorward shift of the SWW linked to a long-term negative phase of the Southern Annular Mode (SAM), which embraced net humid and cold atmospheric conditions in central Chile between the 13th century and the mid-19th century. Our glacier chronology is comparable to others from Patagonia and New Zealand, altogether exposing the culmination of the latest Holocene glacial maximum by the mid-19th century, before overall ice decay in a global warming world, with accelerated ice loss since the mid-20th century. (c) 2022 Elsevier Ltd. All rights reserved.
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    Resolving the paradox of conflicting glacial chronologies: Reconstructing the pattern of deglaciation of the Magellan cordilleran ice dome (53-54°S) during the last glacial - interglacial transition
    (2024) Mcculloch, Robert D.; Bentley, Michael J.; Fabel, Derek; Fernandez-Navarro, Hans; Garcia, Juan-Luis; Hein, Andrew S.; Huynh, Carla; Jamieson, Stewart S. R.; Lira, Maria-Paz; Luethgens, Christopher; Nield, Grace A.; Roman, Manuel San; Tisdall, Eileen W.
    Raised shorelines and associated lacustrine sediments in the central Estrecho de Magallanes (Strait of Magellan) have been interpreted as products of cordilleran glaciers impounding a large proglacial lake and preventing drainage to the South Pacific and Southern Ocean during the Late glacial between c. 15.0 and 12.0 cal ka BP. However, a growing body of glacial geological evidence points towards an earlier retreat of the Magellan cordilleran ice dome, insufficient to dam lakes at that time. We critically re-evaluate the extant evidence for the c. 15.0-12.0 cal ka BP lake, here named 'Lago Kawesqar', and provide further sedimentological and chronological evidence for its existence. We also provide new cosmogenic surface nuclide dating of erratic and bedrock samples collected from extensive field campaigns that confirm the rapid and widespread retreat of the Magellan ice fields to the inner fjords of the Fuegian archipelago by c. 16.0 ka. To resolve the apparent paradox between these two lines of evidence we propose that glacial isostatic adjustment led to a topographic barrier to lake drainage rather than an ice dam. We use Glacial Isostatic Adjustment modelling to demonstrate that rapid isostatic recovery following the early deglaciation after c. 17.0 cal ka BP likely led to elevation of the present shallow south-western coastal margin of the Fuegian archipelago. Final drainage of Lago Kawesqar was probably caused by neotectonic subsidence of the same margin along the boundary of the South American - Scotia tectonic plates at c. 12.0 cal ka BP.