scholarly journals Climate and base-level controlled fluvial system change and incision during the last glacial–interglacial transition, Roer river, the Netherlands – western Germany

2016 ◽  
Vol 96 (2) ◽  
pp. 71-92 ◽  
Author(s):  
C. Kasse ◽  
R.T. Van Balen ◽  
S.J.P. Bohncke ◽  
J. Wallinga ◽  
M. Vreugdenhil
Keyword(s):  
The Netherlands ◽  
Younger Dryas ◽  
System Change ◽  
Late Glacial ◽  
Sediment Supply ◽  
Early Holocene ◽  
Forest Recovery ◽  
Fluvial System ◽  
Base Level ◽  
Western Germany

AbstractThe fluvial development of the Roer river in the southeastern Netherlands and western Germany is presented for the Late Pleniglacial, Late-glacial and Early Holocene periods. Reconstruction of fluvial-style changes is based on geomorphological and sedimentological analysis. Time control comes from correlation to the pollen-based biochronostratigraphic framework of the Netherlands combined with independent optically stimulated luminescence (OSL) ages. At the Pleniglacial to Late-glacial transition a system and channel pattern change occurred from an aggrading braided to an incising meandering system. Rapid rates of meander migration, as established for the Late-glacial by optical dating, were likely related to the sandy nature of the substratum and the Late-glacial incision of the Meuse that resulted in a higher river gradient in the downstream part of the Roer. In the Roer valley the Younger Dryas cooling is not clearly reflected by a fluvial system response, but this may also be related to Holocene erosion of Younger Dryas fluvial forms. An important incision and terrace formation was established at the Younger Dryas to Early Holocene transition, probably related to forest recovery, reduced sediment supply and base-level lowering of the Meuse. The results of this study show a stepwise reduction in the number of channel courses from a multi-channel braided system in the Pleniglacial, to a double meander-belt system in the Late-glacial and a single-channel meandering system in the Early Holocene. The results show that the forcing factors of fluvial-system change in the Roer valley are climate change (precipitation, permafrost and vegetation) and downstream base-level control by the Meuse.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i>δ</i><sup>18</sup>O biomarker paleohygrometer applied to the Gemündener Maar sediments, Western Eifel, Germany

2019 ◽  
Vol 15 (2) ◽  
pp. 713-733 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Unexpected Finding ◽  
Temperature Dependent ◽  
The Past ◽  
Natural Climate

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 and C29) and a hemicellulose-derived sugar biomarker (arabinose), respectively. Both δ2Hn-alkane and δ18Osugar are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. Leaf water reflects δ2H and δ18O of precipitation (primarily temperature-dependent) modified by evapotranspirative enrichment of leaf water due to transpiration. Based on the notion that the evapotranspirative enrichment depends primarily on relative humidity (RH), we apply a previously introduced “coupled δ2Hn-alkane–δ18Osugar paleohygrometer approach” to reconstruct the deuterium excess of leaf water and in turn Late Glacial–Early Holocene RH changes from our Gemündener Maar record. Our results do not provide evidence for overall markedly dry climatic conditions having prevailed during the Younger Dryas. Rather, a two-phasing of the Younger Dryas is supported, with moderate wet conditions at the Allerød level during the first half and drier conditions during the second half of the Younger Dryas. Moreover, our results suggest that the amplitude of RH changes during the Early Holocene was more pronounced than during the Younger Dryas. This included the occurrence of a “Preboreal Humid Phase”. One possible explanation for this unexpected finding could be that solar activity is a hitherto underestimated driver of central European RH changes in the past.

scholarly journals A major hydrobiological change in Dasht-e Arjan Wetland (southwestern Iran) during the late glacial – early Holocene transition revealed by subfossil chironomids

2019 ◽  
Vol 56 (8) ◽  
pp. 848-856
Author(s):  
Cyril Aubert ◽  
Morteza Djamali ◽  
Matthew Jones ◽  
Hamid Lahijani ◽  
Nick Marriner ◽  
...  
Keyword(s):  
Lake Level ◽  
Regional Scale ◽  
Younger Dryas ◽  
Late Glacial ◽  
Early Holocene ◽  
Geochemical Data ◽  
The Holocene ◽  
Chironomus Plumosus ◽  
Subfossil Chironomids ◽  
Southwestern Iran

The late glacial – early Holocene transition is a key period in the earth’s history. However, although this transition is well studied in Europe, it is not well constrained in the Middle East and palaeohydrological records with robust chronologies remain scarce from this region. Here we present an interesting hydrobiological record showing a major environmental change occurring in the Dasht-e Arjan Wetland (southwestern Iran, near to Persepolis) during the late glacial – early Holocene transition (ca. 11 650 years cal BP). We use subfossil chironomids (Insecta: Diptera) as a proxy for hydrological changes and to reconstruct lake-level fluctuations. The Arjan wetland was a deep lake during the Younger Dryas marked by a dominance of Chironomus plumosus/anthracinus-type, taxa adapted to anoxic conditions of deep waters. At the beginning of the Holocene, a drastic decrease (more than 80% to less than 10%) of Chironomus plumosus/anthracinus-type, combined with diversification of littoral taxa such as Polypedilum nubeculosum-type, Dicrotendipes nervosus-type, and Glyptotendipes pallens-type, suggests a lake-level decrease and a more vegetalized aquatic environment. We compare and contrast the chironomid record of Arjan with a similar record from northwestern Iran. The palaeoclimatic significance of the record, at a local and regional scale, is subsequently discussed. The increase in Northern Hemisphere temperatures, inferred by geochemical data from NGRIP, at the beginning of the Holocene best explains the change from the Younger Dryas highstand to early Holocene lowstand conditions in the Dasht-e Arjan wetland. However, a contribution of the meltwater inflow from small local glaciers in the catchment basin is not excluded.

scholarly journals Palynology and Archaeology of Late Vistulian and Early Holocene Sites in Lubuskie Lake District, Western Poland

2014 ◽  
Vol 31 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Iwona Okuniewska-Nowaczyk ◽  
Iwona Sobkowiak-Tabaka
Keyword(s):  
Small Area ◽  
Younger Dryas ◽  
Late Glacial ◽  
Early Holocene ◽  
Lake District ◽  
Multidisciplinary Research ◽  
Late Vistulian ◽  
Palynological Spectrum ◽  
History Of ◽  
Palynological Records

Abstract The Lubuskie Lake District played an important part in recolonisation of the Polish Plain due to its location and the character of the terrain. Despite that, it is and especially its northern part, poorly explored regarding both history of Late Glacial and early Holocene settlements, and the natural environment. The paper presents results of multidisciplinary research in this area. The most spectacular discoveries were connected with remains of settlements of the Hamburgian culture societies at Myszęcin - currently the richest site of this culture over the entire North European Plain. In the vicinity of this site several Late Palaeolithic and Mesolithic settlements of varied functions were recorded. First palynological records came from the Younger Dryas sediments in this area. In a log with a palynological spectrum comprising Younger Dryas and the beginning of the Holocene, a charcoal dust was found and it could indicate human activity as humans lived at a lake shore. An important complement to the image of the Late Glacial settlement at the Lubuskie Lake District was provided by the research near Lubrza that resulted in data regarding settlements of the Federmesser and Świderian culture societies. This region was not typical in a palynological spectrum of deposits during Allerød but also indicated highly diversified thickness of basal peat in a small area.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled δ<sup>2</sup>H-δ<sup>18</sup>O biomarker paleohygrometer, applied to the Lake Gemündener Maar sediments, Western Eifel, Germany

2018 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Vegetation Period ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
Natural Climate

Abstract. The Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in Central Europe during the Late Glacial, are considered crucial for understanding rapid natural climate change in the past. The sediments from Maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from Lake Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf wax-derived lipid biomarkers (n-alkanes C27 and C29) and hemicellulose-derived sugar biomarkers (arabinose), respectively. Both δ2H and δ18O are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. This enables the coupling of the results via a δ2H-δ18O biomarker paleohygrometer approach and allows calculating past relative air humidity values, which is the major advantage of the applied approach. Fundamental was the finding that the isotopic enrichment of leaf water due to evapotranspiration depends mainly on relative humidity. We hence use the coupled δ2H-δ18O biomarker approach to reconstruct the deuterium-excess of leaf water and in turn relative air humidity values corresponding to the vegetation period and daytime (RHdv). Most importantly, the results of the coupled δ2H-δ18O biomarker paleohygrometer approach (i) support a two-phasing of the Younger Dryas, i.e. a relative wet phase (on Allerød level) followed by a drier Younger Dryas ending, (ii) do not corroborate overall drier climatic conditions characterising the Younger Dryas or a two-phasing with regard to a first dry and cold Younger Dryas phase followed by a warmer period along with increasing precipitation amounts, and (iii) suggest that the amplitude of RHdv changes during the Early Holocene was more pronounced compared to the Younger Dryas. One possible driver for the unexpected Lake Gemündener Maar RHdv variations could be the solar activity.

scholarly journals KVARTÉRNÍ SEDIMENTY NA SEVERNÍM PŘEDHRADÍ LOKALITY POHANSKO U BŘECLAVI

2018 ◽  
Vol 25 (1-2) ◽  
Author(s):  
Slavomir Nehyba ◽  
Marie Dvořáková ◽  
Nela Doláková ◽  
Petr Dresler
Keyword(s):  
Younger Dryas ◽  
Late Glacial ◽  
Osl Dating ◽  
Early Holocene ◽  
Channel Migration ◽  
Facies Association ◽  
Upper Pleistocene ◽  
Channel Ratio ◽  
Two Samples ◽  
Facies Associations

Sedimentological study on the Northern bailey of the fortified site Pohansko allows identification of 9th lithofacies and 2 facies associations. The lower facies association is interpreted as an infill of fluvial channels (mostly mid-channel dunes) with two cycles of filling. The fluvial channels were relatively shallow and broad (high width/depth channel ratio) and they point to braided fluvial style and channel migration. The upper fluvial association reflects significant change of the fluvial style. The sedimentary infill of the upper fluvial association is interpreted as deposits of levee and overbank deposits. Results of the OSL dating for the sample of lower facies association provide an age of 13.5 ky. Such age can be correlated with the Upper Pleistocene Allerød Interstadial (13.7‒12.9 ky BP), i.e. relatively warmer phase of the Weichselian late glacial. Data of OSL dating for two samples from the upper facies association were 11.8 ky and 10.3 ky BP. The upper age can be correlated with Younger Dryas (12.9‒11.7 ky BP) whereas the lower one to Preboreal. The deposition of the upper facies associations are therefore interpreted as Uppermost Pleistocene to Early Holocene in age.

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