New chronologic and stratigraphic constraints from the Garda morainic amphitheater define the extension of the last glaciation in the Adige-Sarca system and improve the Alpine LGM dataset. Together ...with the available chronology of the Rhine and Tagliamento systems, our results indicate a synchronous maximum culmination of Alpine glaciers during the LGM, which anticipated by about 3.5 ka the maximum extension of the Eurasian Ice Sheet (EIS). This is ascribed to the sensitivity of Alpine glaciers to the availability of moisture from southerly circulation, as recently documented by speleothem δ
O curve from Sieben Hengste (7 H). According to global circulation models, the waxing of the North American Ice Sheet (NAIS) at 26-23 ka pushed the North Atlantic jet stream southwards. This enhanced precipitation rates in southern Europe by advection of moisture from the Mediterranean Sea, triggering expansion of the Alpine glaciers. NAIS waning after 23 ka led to the gradual re-establishment of westerly circulation and renewal of a moisture supply to northern Europe, feeding the EIS to its maximum volume. Reduced supply of moisture from the Mediterranean Sea sealed the fate of the Alpine glaciers, which entered a final recessional phase after 22 ka and faded out after 17.5 ka.
Geomorphological field surveys and mapping have been carried out in a catchment of the Dolomites (eastern Italian Alps) as part of a research project aiming at the assessment of sediment availability ...for mass wasting in mountain environments. The study area is the Liera catchment which was severely affected by a high-intensity, regional-scale storm named 'Vaia' (27-30 October 2018), which induced relevant morphological changes, caused a major flood in the main stream and triggered debris flows in many tributaries. This contribution gives a snapshot of the present-day state of the study area to improve the understanding of such a landscape by characterizing the processes that control its geomorphological spatio-temporal dynamics and evolution.
Abstract
A 3800 year-long radiocarbon-dated and highly-resolved palaeoecological record from Lake Fimon (N-Italy) served to investigate the effects of potential teleconnections between North Atlantic ...and mid-to-low latitudes at the transition from Marine Isotope Stage (MIS) 3 to 2. Boreal ecosystems documented in the Fimon record reacted in a sensitive way to millennial and sub-millennial scale Northern Hemisphere atmospheric circulation patterns. The high median time-resolution of 58 years allows the identification of five abrupt event-boundaries (i.e., main forest expansion and decline excursions) synchronous with the sharp stadial/interstadial (GS/GI) transitions within dating uncertainties. During Heinrich Stadial 3 (HS 3) we reconstruct more open and dry conditions, compared to the other GS, with a dominant regional scale fire signal. Linkages between local fires and climate-driven fuel changes resulted in high-magnitude fire peaks close to GI/GS boundaries, even exacerbated by local peatland conditions. Finally, palaeoecological data from the HS 3 interval unveiled an internal variability suggesting a peak between 30,425 and 29,772 cal BP (2σ error) which matches more depleted δ
18
O values in alpine speleothems. We hypothesise that this signal, broadly resembling that of other mid-latitudes proxies, may be attributed to the southward shift of the Northern Hemisphere storm tracks and the associated delayed iceberg discharge events as documented during other HS.
A comprehensive geomorphological and structural mapping of the largest landslides in the central-eastern Southern Alps (NE Italy) is presented. Their occurrence in this Alpine sector is discussed in ...relation with structural geological features (bedding and faults), which are largely conditioned by the Giudicarie and Schio-Vicenza regional fault systems. Tectonic rock damaging here coexists with high relief stored energy and active deformation, which is testified by present seismicity and cumulative earthquake moment release. Based on updated rock failure ages, slope activity is concentrated at 5-3 and 1 ka, as primarily enhanced by climatic and seismic controls. The analysis of predisposing and driving factors poses the question of present and future landslide hazards for these densely inhabited Alpine valleys.
We applied a multi-method approach to reconstruct the Gorte rock avalanche (85–95 Mm3) located at the northeastern end of Lake Garda. The combination of field mapping, characterization of bedrock ...discontinuities, Dan3D-Flex runout modeling and dating of boulders with cosmogenic 36Cl supports the conclusion that the deposits stem from a single rock avalanche at 6.1 ± 0.8 ka. The Gorte event may have triggered the Spiaz de Navesele–Salto della Capra landslide (3.2 Mm3), whose deposits cover the southern end of the Gorte deposits. First-order controls on detachment were the NNE–SSW- and WNW–ESE-oriented fractures in the limestone bedrock, related to the Giudicarie and Schio-Vicenza fault systems, respectively. Dan3D-Flex runout modeling sufficiently reproduced the Gorte rock avalanche, which involved detachment and sliding of a quasi-intact block, likely along marly interbeds, followed by rapid disintegration. The frictional rheology in the source area and the turbulent frictional rheology (Voellmy) in the remaining part best replicate the observed deposit extent and thickness. Heavy precipitation that occurred at that time may have contributed to failure at Gorte. Nonetheless, its timing overlaps with the nearby (<15 km) Dosso Gardene (6630–6290 cal BP) and Marocca Principale (5.3 ± 0.9 ka) landslides, making a seismic trigger plausible.
We consider an open multiwing system, composed of N ≥ 2 disjoint open plane curves, not necessarily symmetric, and examine the corresponding (constrained) induced drag minimization problem. To this ...end, we first derive the associated Euler‐Lagrange system of equations, which is then reduced to an equivalent system of Cauchy singular integral equations. By generalizing a previous approach of ours for the case of a single open wing, we obtain existence and uniqueness results for the problem solution in a product of weighted Sobolev type spaces. This system is then solved by applying to it a collocation‐quadrature method. For this, we prove stability and derive corresponding error estimates. Finally, to test the efficiency of the proposed numerical method, we apply it to some multiwing systems.
•The Monte Cavallo hosted an isolated glacial system (ca. 37 km2) during the LGM.•LGM ELAs in the south-eastern Alps were between 1100 and 1700 m.•Reconstructed palaeoprecipitation is similar to the ...modern-day climate.•Mediterranean moisture advection was key for glacier development.•Lake sediments in the Caltea Valley relate to a pre-LGM interstadial (>45 ka BP)
Glacier-based reconstructions of Equilibrium Line Altitudes (ELAs) are important to understand changes of temperature and precipitation over longer time scales and may help to validate regional palaeoclimate models. Here, we present new insights into the ELA in the south-eastern part of the European Alps during the Last Glacial Maximum (LGM, 26.5 to 19 ka), based on the geomorphological record of the Monte Cavallo Group (Venetian Prealps, NE-Italy). This mountain range hosted a glacial system that remained isolated from larger valley glaciers in its vicinity and therefore likely responded very dynamically to changes in climatic boundary conditions. Through detailed mapping of glacial sediments and landforms, we were able to constrain the extent of these palaeoglaciers and model their surface geometry and ELA via semi-automated toolboxes in a geographic information system. In the absence of numerical datings, these landforms were related to an LGM advance through geomorphological and stratigraphical means. In a next step, ELAs were also recalculated for other LGM glaciers in the south-eastern Alps, allowing wider palaeoclimatic conclusions to be drawn. These ELAs are in the range of 1100 to almost 1700 m and show a strong E-W gradient with particular low values in the Julian and eastern Carnic Prealps. This pattern indicates that during the LGM a precipitation gradient existed along the south-eastern fringe of the Alps, with moisture being preferentially advected to these mountain ranges while the Venetian Prealps in the West received less precipitation. Based on the reconstructed ELAs, annual precipitation sums during the regional LGM glacier culmination (ca. 25.5 to 23.5 ka) are estimated between 1820 and 2920 ± 750 mm/yr. Those values are largely compatible with data from modern weather stations and indicate no or little reduction in LGM precipitation as it is reported from other parts of the Alps.
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