Early Pleistocene complex cut-and-fill sequences in the Alps

2021 ◽  
Author(s):  
Catharina Dieleman ◽  
Marcus Christl ◽  
Christof Vockenhuber ◽  
Philip Gautschi ◽  
Naki Akçar
Keyword(s):  
Depositional Environment ◽  
Early Pleistocene ◽  
Cosmogenic Nuclide ◽  
Base Level ◽  
Drainage Patterns ◽  
Northern Alpine Foreland ◽  
First Onset ◽  
The Alps ◽  
Alpine Foreland ◽  
Cut And Fill

<p>Deckenschotter (Cover Gravels in German) are Quaternary glacio-fluvial gravels, which unconformably overlie Tertiary Molasse or Mesozoic bedrock in the Northern Alpine Foreland. They comprise also the evidence of the Early Pleistocene glaciations. A significant phase of incision separated them into Höhere Deckenschotter (HDS: Higher Cover Gravels) and Tiefere Deckenschotter (TDS: Lower Cover Gravels) based on their topography. How the landscape evolved during Deckenschotter times is still not fully understood. The new cosmogenic nuclide chronology suggests that HDS deposited around 2 Ma and TDS around 1 Ma. In addition, 2 Ma old Deckenschotter are located at the same topographic elevation as the 1 Ma ones at Irchel (Canton of Zurich). This, indeed, points to cut-and-fill sequences and challenges the chronology based on the morphostratigraphy.</p><p>The aim of this study is to reconstruct the drainage patterns, base level changes, and thus the landscape evolution in the northern Alpine Foreland during the Early Pleistocene. Therefore, we focused on three Deckenschotter sites at Irchel and one in the area around Lake Constance. Sediments at these sites were analysed in detail to reveal their provenance, transport mechanism, depositional environment, and paleoflow regimes. Their chronology was established by isochron-burial dating. Our results indicate that the analysed sediments were transported from the Central and eastern Central Alps as well as from the Molasse to the foreland first by glaciers and then by rivers. They are deposited in a glacio-fluvial environment in the vicinity of a glacier. Based on the reconstructed chronology in this study and published cosmogenic nuclide ages, we propose that Deckenschotter are cut-and-fill sequences accumulated in three pulses between 2.5 Ma and 1 Ma. This cut-and-fill system implies that the regional base level was relatively constant during the Early Pleistocene. In addition, the depositional environment of Deckenschotter shows the presence of glaciers in the foreland. The 2.5 Ma old gravels, therefore, document the first advance of glaciers onto the Alpine Foreland. This seems to be synchronous with a first onset of glaciations on the northern hemisphere, which is assumed to occur at around 2.7 Ma.</p>

The effects of lithology and base level on topography in the northern alpine foreland

Geomorphology ◽  
2018 ◽  
Vol 313 ◽  
pp. 13-26 ◽  
Author(s):  
Sebastian Baumann ◽  
Jörg Robl ◽  
Günther Prasicek ◽  
Bernhard Salcher ◽  
Melanie Keil
Keyword(s):  
Base Level ◽  
Northern Alpine Foreland ◽  
Alpine Foreland

The Missing Link between Terrain-Induced Potential Vorticity Banners and Banded Convection

2016 ◽  
Vol 144 (11) ◽  
pp. 4063-4080 ◽  
Author(s):  
Simon K. Siedersleben ◽  
Alexander Gohm
Keyword(s):  
Convective Cloud ◽  
Small Scale ◽  
Topographic Features ◽  
Inertial Instability ◽  
Northern Alpine Foreland ◽  
Southern Side ◽  
Northern Side ◽  
The Alps ◽  
Alpine Foreland ◽  
Conditional Instability

Abstract On 1 February 2014, the southern side of the Alps was affected by a severe snowstorm that forced authorities to issue the highest level of avalanche danger in southern parts of Austria. The northern side of the Alps was mostly dry. Nevertheless, radar imagery captured the evolution of quasi-steady convective cloud bands over the northern Alpine foreland with a remarkable length of up to 300 km. This study illuminates the processes that generated these cloud bands based on numerical simulations. The storm was associated with a deep large-scale trough that caused strong southwesterly cross-Alpine flow, orographic precipitation on the southern side, and foehnlike subsidence on the northern side of the Alps. Orographic potential vorticity (PV) banners developed at small-scale topographic features embedded in the Alps and extended downstream over the northern Alpine foreland. Convective cloud bands were aligned parallel to these PV banners. They formed in an environment of inertial instability (negative absolute vorticity) and conditional instability. Sensitivity experiments reveal that the structure and size of these cloud bands are strongly sensitive to the small-scale terrain roughness. Removing small-scale topographic features suppresses the formation of orographic vorticity banners, which in turn suppresses the development of cloud bands. These results suggest that the release of inertial instability at negative orographic vorticity banners was crucial for establishing circulations and associated uplift that triggered conditional instability. To summarize, inertial instability was most likely responsible for the banded structure and conditional instability for the convective nature of these cloud bands.

scholarly journals New chronological constraints on the timing of Late Pleistocene glacier advances in northern Switzerland

2019 ◽  
Vol 68 (1) ◽  
pp. 53-73 ◽  
Author(s):  
Dorian Gaar ◽  
Hans Rudolf Graf ◽  
Frank Preusser
Keyword(s):  
Late Pleistocene ◽  
Northern Switzerland ◽  
Stage 4 ◽  
Glacier Dynamics ◽  
Northern Alpine Foreland ◽  
The Alps ◽  
Alpine Foreland ◽  
Methodological Considerations ◽  
Age Constraints ◽  
Partial Bleaching

Abstract. Deposits of the Reuss Glacier in the central northern Alpine foreland of Switzerland are dated using luminescence methodology. Methodological considerations on partial bleaching and fading correction of different signals imply the robustness of the results. An age of ca. 25 ka for sediment directly overlying basal lodgement till corresponds well with existing age constraints for the last maximal position of glaciers of the northern Swiss Alpine Foreland. Luminescence ages imply an earlier advance of Reuss Glacier into the lowlands during Marine Isotope Stage 4. The presented data are compared to findings from other parts of the Alps regarding glacier dynamics and palaeoclimatological implications, such as the source of precipitation during the Late Pleistocene.

scholarly journals Volcanism and Volcanogenic Submarine Sedimentation in the Paleogene Foreland Basins of the Alps: Reassessing the Source-to-Sink Systems with an Actualist View

Geosciences ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 23
Author(s):  
Andrea Di Capua ◽  
Federica Barilaro ◽  
Gianluca Groppelli
Keyword(s):  
Foreland Basin ◽  
Fault System ◽  
Foreland Basins ◽  
The North ◽  
Source To Sink ◽  
The Alps ◽  
Alpine Foreland ◽  
Alpine Foreland Basin ◽  
Tectonic Lineament ◽  
First Time

This work critically reviews the Eocene–Oligocene source-to-sink systems accumulating volcanogenic sequences in the basins around the Alps. Through the years, these volcanogenic sequences have been correlated to the plutonic bodies along the Periadriatic Fault System, the main tectonic lineament running from West to East within the axis of the belt. Starting from the large amounts of data present in literature, for the first time we present an integrated 4D model on the evolution of the sediment pathways that once connected the magmatic sources to the basins. The magmatic systems started to develop during the Eocene in the Alps, supplying detritus to the Adriatic Foredeep. The progradation of volcanogenic sequences in the Northern Alpine Foreland Basin is subsequent and probably was favoured by the migration of the magmatic systems to the North and to the West. At around 30 Ma, the Northern Apennine Foredeep also was fed by large volcanogenic inputs, but the palinspastic reconstruction of the Adriatic Foredeep, together with stratigraphic and petrographic data, allows us to safely exclude the Alps as volcanogenic sources. Beyond the regional case, this review underlines the importance of a solid stratigraphic approach in the reconstruction of the source-to-sink system evolution of any basin.

scholarly journals Cosmogenic burial dating of in cave-deposited alluvium: unravelling long-term incision rates and complex speleogenesis in multi-level cave systems

2020 ◽  
Author(s):  
Gilles Rixhon ◽  
Didier L. Bourlès ◽  
Régis Braucher ◽  
Alexandre Peeters ◽  
Alain Demoulin
Keyword(s):  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Fluvial Terrace ◽  
Base Level ◽  
Cave System ◽  
River Incision ◽  
Order Of Magnitude ◽  
History Of ◽  
Multi Level

<p>Multi-level cave systems record the history of regional river incision in abandoned alluvium-filled phreatic passages which, mimicking fluvial terrace sequences, represent former phases of fluvial base-level stability. In this respect, cosmogenic burial dating of in cave-deposited alluvium (usually via the nuclide pair <sup>26</sup>Al/<sup>10</sup>Be) represents a suitable method to quantify the pace of long-term river incision. Here, we present a dataset of fifteen <sup>26</sup>Al/<sup>10</sup>Be burial ages measured in fluvial pebbles washed into a multi-level cave system developed in Devonian limestone of the uplifted Ardenne massif (eastern Belgium). The large and well-documented Chawresse system is located along the lower Ourthe valley (i.e. the main Ardennian tributary of the Meuse river) and spans altogether an elevation difference exceeding 120 m.</p><p>The depleted <sup>26</sup>Al/<sup>10</sup>Be ratios measured in four individual caves show two main outcomes. Firstly, computed burial ages ranging from ~0.2 to 3.3 Ma allows highlighting an acceleration by almost one order of magnitude of the incision rates during the first half of the Middle Pleistocene (from ~25 to ~160 m/Ma). Secondly, according to the relative elevation above the present-day floodplain of the sampled material in the Manants cave (<35 m), the four internally-consistent Early Pleistocene burial ages highlight an “anomalous” old speleogenesis in the framework of a gradual base-level lowering. They instead point to intra-karsting reworking of the sampled material in the topographically complex Manants cave. This in turn suggests an independent, long-lasting speleogenetic evolution of this specific cave, which differs from the <em>per descensum</em> model of speleogenesis generally acknowledged for the regional multi-level cave systems and their abandoned phreatic galleries. In addition to its classical use for inferring long-term incision rates, cosmogenic burial dating can thus contribute to better understand specific and complex speleogenetic evolution.</p>

scholarly journals Cosmogenic nuclide dating of cave sediments in the Eastern Alps and implications for erosion rates

2020 ◽  
Vol 49 (2) ◽  
pp. 107-118
Author(s):  
Philipp Häuselmann ◽  
◽  
Lukas Plan ◽  
Peter Pointner ◽  
Markus Fiebig ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Eastern Alps ◽  
Western Alps ◽  
Valley Bottom ◽  
Cosmogenic Nuclide ◽  
Base Level ◽  
Multi Level ◽  
Slow Evolution ◽  
Karst Systems ◽  
Cosmogenic Nuclide Dating

Karstic caves are created by water eroding and corroding rocks that can be dissolved. Since both the spring areas of caves (normally at the valley bottom) as well as the recharge is controlled by superficial processes, the morphology of the cave bears strong links to these influences. Lowering of local base levels promotes the development of horizontal phreatic cave passages at progressively lower elevations, resulting in the formation of multi-level karst systems. Upon the next lowering of base level, these upper systems become fossilized, and sediment trapped within them may remain preserved for millions of years. Dating these sediments gives clues regarding the time when the passages were last active, and thus may yield age information for old valley floors. The present paper presents cosmogenic nuclide datings of twelve samples from eight caves in the central part of the Northern Calcareous Alps of Austria. Besides three samples that gave no results, most of the obtained ages are at the Mio-Pliocene boundary or within the Pliocene, as was expected before sampling. No multi-level caves could be sampled at different elevations, thus, the obtained valley deepening rates are averages between the age of sediment deposition and the present-day valley floor. However, the valley deepening rates of 0.12 to 0.21 km/Ma are in accordance to previous findings and corroborate a comparatively slow evolution of base level lowering in the Eastern Alps compared to the fast (Late Quaternary) evolution in the Central and Western Alps.

Sign in / Sign up

Export Citation Format

Share Document