We identify the precise hallmarks of the local magnetic moment formation and its Kondo screening in the frequency structure of the generalized charge susceptibility. The sharpness of our ...identification even pinpoints an alternative criterion to determine the Kondo temperature of strongly correlated systems on the two-particle level, which only requires calculations at the lowest Matsubara frequency. We showcase its strength by applying it to the single impurity and the periodic Anderson model as well as to the Hubbard model. Our results represent a significant progress for the general understanding of quantum field theory at the two-particle level and allow for tracing the limits of the physics captured by perturbative approaches for correlated systems.
While the breakdown of the perturbation expansion for the many-electron problem has several formal consequences, here we unveil its physical effect: flipping the sign of the effective electronic ...interaction in specific scattering channels. By decomposing local and uniform susceptibilities of the Hubbard model via their spectral representations, we prove how entering the nonperturbative regime causes an enhancement of the charge response, ultimately responsible for the phase-separation instabilities close to the Mott metal-insulator transition. Our analysis opens a new route for understanding phase transitions in the nonperturbative regime and clarifies why attractive effects emerging from a strong repulsion can induce phase separations but not s -wave pairing or charge-density wave instabilities.
Based on high‐resolution (sub)glacial geomorphological mapping, we present a first digital inventory of streamlined bedforms within the footprint of a Last Glacial Maximum (LGM) Alpine piedmont ...glacier. A total of 2460 drumlins were mapped across the Rhine glacier foreland. Glacial lineations and one field of subglacial ribs (ribbed/Rogen moraines) — the first record of this type of subglacial landform on the Alpine foreland—were identified. Two flowsets, associated with (i) the Rhine glacier's LGM maximum advance (Schaffhausen stadial) and (ii) a late LGM readvance (Stein am Rhein stadial), are differentiated. The vast majority of streamlined bedforms occur in fields aligned in a 16‐ to 30‐km‐wide swath upstream of the Stein am Rhein frontal moraines. Orientation and elongation of drumlins and glacial lineations set the basis for the reconstruction of paleo‐ice flow. Basal flow paths of the LGM maximum advance are visually interpreted and restricted to the zone proximal to the former ice front. The flow field reconstructed for the late LGM glacier readvance (Stein am Rhein stadial) extends tens of kilometres upstream and is modelled implementing a recently published kriging routine. The derived basal flow patterns paired with information on ice surface levels from lateral and frontal moraines and combined with relative ice velocity differences inferred from spatial changes in bedform elongation reveal detailed insights on ice flow geometries, particularly during the glacier readvance. Reconstructed flowlines highlight basal flow under shallow ice that is strongly controlled by local topography evidenced by diverging around basal bumps and converging in (narrow) valley sections and troughs, where basal flow velocities, steered by topography, are high. Gained paleo‐ice basal flow patterns offer new insights on landscape evolution of the northern Alpine foreland and provide evidence‐based flow data to validate future physical modelling results.
More than 2500 bedforms (drumlins, glacial lineations and subglacial ribs) were mapped in the footprint of the Last Glacial Maximum Rhine glacier piedmont lobe (6000 km2). Elongation and direction of mapped subglacially streamlined bedforms were used to reconstruct the paleoglacier's flow pattern during a late LGM readvance. Basal trajectories that diverge around bedrock highs and converge in narrow valley sections, as well as identified fast flow areas, that largely correspond to valley troughs, underline the strong topographical control on ice flow.
This paper reviews the current state of knowledge about environmental changes at the MIS 3/2 transition in the northern Alps and their foreland, covering the time frame from 35 to 25 ka. Lake and ...peat deposits, cave sediments, loess and glacial deposits are presented and the response of their biotic and abiotic proxies to climate change is discussed. During late MIS 3, interstadial conditions, albeit weak, occurred at c. 36–32 ka. At climatically favourable sites, small patches of trees (mainly Pinus and some Betula) existed together with some shrubs. The environmental conditions during late MIS 3 are also reflected by a boreal brown soil horizon, a cambisol called Lohne soil, found in many loess sequences. Subsequently, the environmental conditions became harsher as shown by the proxy data. From c. 30 ka onwards the absence of pedogenesis sensu stricto and the plant assemblages point to an Arctic climate in the northern Alpine foreland. Accentuating, glaciers advanced beyond the northern limit of the Alps around the MIS 3/2 boundary and reached their maximum extent in the foreland at about 25 ka.
Overdeepened valleys and basins are commonly found below the present landscape surface in areas that were affected by Quaternary glaciations. Overdeepened troughs and their sedimentary fillings are ...important in applied geology, for example, for geotechnics of deep foundations and tunnelling, groundwater resource management, and radioactive waste disposal. This publication is an overview of the areal distribution and the geometry of overdeepened troughs in the Alps and their foreland, and summarises the present knowledge of the age and potential processes that may have caused deep erosion. It is shown that overdeepened features within the Alps concur mainly with tectonic structures and/or weak lithologies as well as with Pleistocene ice confluence and partly also diffluence situations. In the foreland, overdeepening is found as elongated buried valleys, mainly oriented in the direction of former ice flow, and glacially scoured basins in the ablation area of glaciers. Some buried deeply incised valleys were generated by fluvial down-cutting during the Messinian crisis but this mechanism of formation applies only for the southern side of the Alps. Lithostratigraphic records and dating evidence reveal that overdeepened valleys were repeatedly occupied and excavated by glaciers during past glaciations. However, the age of the original formation of (non-Messinian) overdeepened structures remains unknown. The mechanisms causing overdeepening also remain unidentified and it can only be speculated that pressurised meltwater played an important role in this context.
Drill cores from the inner-alpine valley terrace of Unterangerberg, located in the Eastern Alps of Austria, offer first insights into a Pleistocene sedimentary record that was not accessible so far. ...The succession comprises diamict, gravel, sand, lignite and thick, fine grained sediments. Additionally, cataclastic deposits originating from two paleo-landslide events are present. Multi-proxy analyses including sedimentological and palynological investigations as well as radiocarbon and luminescence data record the onset of the last glacial period (Würmian) at Unterangerberg at ∼120–110 ka. This first time period, correlated to the MIS 5d, was characterised by strong fluvial aggradation under cold climatic conditions, with only sparse vegetation cover. Furthermore, two large and quasi-synchronous landslide events occurred during this time interval. No record of the first Early Würmian interstadial (MIS 5c) is preserved. During the second Early Würmian interstadial (MIS 5a), the local vegetation was characterised by a boreal forest dominated by Picea, with few thermophilous elements. The subsequent collapse of the vegetation is recorded by sediments dated to ∼70–60 ka (i.e. MIS 4), with very low pollen concentrations and the potential presence of permafrost. Climatic conditions improved again between ∼55 and 45 ka (MIS 3) and cold-adapted trees re-appeared during interstadials, forming an open forest vegetation. MIS 3 stadials were shorter and less severe than the MIS 4 at Unterangerberg, and vegetation during these cold phases was mainly composed of shrubs, herbs and grasses, similar to what is known from today's alpine timberline. The Unterangerberg record ended at ∼45 ka and/or was truncated by ice during the Last Glacial Maximum.
► We investigated drillcores from a site inside the Eastern Alps of Austria. ► The Late Pleistocene sedimentation history of a palaeolake was reconstructed. ► Pollen analysis gives insights into environmental dynamics during stadials and interstadials. ► Impacts of last glacial climate changes on Alpine vegetation can be traced.
Results of a geological re-investigation of the type localities of the Bühl stadial, the supposed first halt during ice decay of the Inn glacier in the basin of Hopfgarten and at the southern flank ...of the mountain range Wilder Kaiser (Northern Tyrol, Austria) are presented. It is shown that in this region no stationary or advancing Inn glacier tongue existed following the Last Glacial Maximum (LGM) ice extent. All sedimentary and morphological evidence indicates that large parts of the Inn glacier and all other Eastern Alpine valley glaciers became stagnant followed by massive down wasting. Hence, this period after the LGM, at the beginning of Termination I (∼Würm-Lateglacial), is best defined as “phase of early Lateglacial ice decay”, which can be tentatively correlated to Greenland Stadial 2c (21.2–19.5
kyr
BP). Only smaller glaciers advanced towards their Lateglacial Maximum Position (LMP). This happened mostly due to short-lasting climatic oscillations as indicated in the Windau valley (Hopfgarten) and at Steinach am Brenner. A mechanically induced glacier advance is reconstructed for the cirque glaciers of the Wilder Kaiser. At an advanced stage of down melting they lost their blockade established by the Inn glacier during LGM and advanced downvalley. It is proposed to define the processes of this phase by lithostratigraphic type-sections.
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