Late-Glacial and Early Holocene environmental changes affecting the shallow lake basin of La Narce du Béage (Ardèche, Massif Central, France)

Author(s):  
André-Marie Dendievel ◽  
Karen Serieyssol ◽  
Benjamin Dietre ◽  
Hervé Cubizolle ◽  
Amélie Quiquerez ◽  
...  
2020 ◽  
Vol 230 ◽  
pp. 106167 ◽  
Author(s):  
José Antonio López-Sáez ◽  
Rosa M. Carrasco ◽  
Valentí Turu ◽  
Blanca Ruiz-Zapata ◽  
María José Gil-García ◽  
...  

2009 ◽  
Vol 203 (1-2) ◽  
pp. 105-112 ◽  
Author(s):  
Tatjana Boettger ◽  
Achim Hiller ◽  
Frank W. Junge ◽  
Dietrich Mania ◽  
Konstantin Kremenetski

2010 ◽  
Vol 7 (10) ◽  
pp. 3083-3094 ◽  
Author(s):  
J. M. Reed ◽  
A. Cvetkoska ◽  
Z. Levkov ◽  
H. Vogel ◽  
B. Wagner

Abstract. Lake Ohrid is a site of global importance for palaeoclimate research. This study presents results of diatom analysis of a ca. 136 ka sequence, Co1202, from the northeast of the lake basin. It offers the opportunity to test diatom response across two glacial-interglacial transitions and within the Last Glacial, while setting up taxonomic protocols for future research. The results are outstanding in demonstrating the sensitivity of diatoms to climate change, providing proxy evidence for temperature change marked by glacial-interglacial shifts between the dominant planktonic taxa, Cyclotella fottii and C. ocellata, and exact correlation with geochemical proxies to mark the start of the Last Interglacial at ca. 130 ka. Importantly, diatoms show much stronger evidence in this site for warming during MIS3 than recorded in other productivity-related proxies, peaking at ca. 39 ka, prior to the extreme conditions of the Last Glacial maximum. In the light of the observed patterns, and from the results of analysis of early Holocene sediments from a second core, Lz1120, the lack of a response to Late Glacial and early Holocene warming from ca. 14.7–6.9 ka suggests the Co1202 sequence may be compromised during this phase. After ca. 7.4 ka, there is evidence for enhanced nutrient enrichment compared to the Last Interglacial, followed by a post-Medieval loss of diversity which is consistent with cooling, but not definitive. Taxonomically, morphological variability in C. fottii shows no clear trends linked to climate, but an intriguing change in central area morphology occurs after ca. 48.7 ka, coincident with a tephra layer. In contrast, C. ocellata shows morphological variation in the number of ocelli between interglacials, suggesting climatically-forced variation or evolutionary selection pressure. The application of a simple dissolution index does not track preservation quality very effectively, underlining the importance of diatom accumulation data in future studies.


2010 ◽  
Vol 29 (2) ◽  
pp. 119-133 ◽  
Author(s):  
Ian Boomer ◽  
Francois Guichard ◽  
Gilles Lericolais

Abstract. During the last glacial phase the Black Sea basin was isolated from the world's oceans due to the lowering of global sea-levels. As sea-levels rose during the latest glacial and early Holocene period, the Black Sea was once again connected to the eastern Mediterranean via the Dardanelles–Marmara–Bosporus seaway. In recent years, trace element and stable isotope analyses of ostracod assemblages have yielded important details regarding the hydrological evolution of the Black Sea during these events. Despite this focus on the geochemical signatures of the ostracods, little if any attention has been paid to the taxonomic composition of the ostracod assemblages themselves and there are notably few publications on the sub-littoral fauna of this important water body. We present a summary of the most abundant ostracod taxa of the Black Sea during the late glacial to early Holocene phase (dominated by the Candonidae, Leptocytheridae and Loxoconchidae) and chart their response to the subsequent environmental changes in the early Holocene with the pre-connection, low salinity ‘lacustrine’ fauna being replaced by one with a more Mediterranean aspect. Many of these taxa are illustrated using SEM for the first time, providing an important initial step in establishing taxonomic stability within Black Sea ostracod studies and noting faunal similarities with neighbouring areas, such as the Caspian Sea.


2019 ◽  
Vol 2 ◽  
pp. 83-88 ◽  
Author(s):  
Sebastian Lorenz ◽  
Henrik Rother ◽  
Michael Kenzler ◽  
Sara Kaphengst

Abstract. The site at the southern shore of Krakower See shows the Quaternary geology of the surrounding area. The local Quaternary sequence comprises a thickness of 50–100 m of Quaternary deposits while the surface morphology is dominated by the ice marginal position of the Pomeranian moraine, which passes through the area. The bathymetry of the lake basin of Krakower See indicates a predominant genesis by glaciofluvial erosion in combination with glacial exaration. Past research in this area has focussed on the reconstruction of Pleniglacial to Holocene environmental changes, including lake-level fluctuations, aeolian dynamics, and pedological processes and their modification by anthropogenic land use.


2002 ◽  
Vol 58 (3) ◽  
pp. 261-272 ◽  
Author(s):  
Barbara Wohlfarth ◽  
Ludmila Filimonova ◽  
Ole Bennike ◽  
Leif Björkman ◽  
Lars Brunnberg ◽  
...  

AbstractHigh-resolution lithostratigraphy, mineral magnetic, carbon, pollen, and macrofossil analyses, and accelerator mass spectrometry 14C measurements were performed in the study of a sediment sequence from Lake Tambichozero, southeastern Russian Karelia, to reconstruct late-glacial and early Holocene aquatic and terrestrial environmental changes. The lake formed ca. 14,000 cal yr B.P. and the area around the lake was subsequently colonized by arctic plants, forming patches of pioneer communities surrounded by areas of exposed soil. A minor rise in lake productivity and the immigration of Betula pubescens occurred ca. 11,500 cal yr B.P. The rise in summer temperatures probably led to increased melting of remnant ice and enhanced erosion. The distinct increase in lake productivity and the development of open Betula-Populus forests, which are reconstructed based on plant macrofossil remains, indicate stable soils from 10,600 cal yr B.P. onward. Pinus and Picea probably became established ca. 9900 cal yr B.P.


2021 ◽  
Author(s):  
Sebastian Schaller ◽  
Michael E. Boettcher ◽  
Marius W. Buechi ◽  
Laura S. Epp ◽  
Stefano C. Fabbri ◽  
...  

<p>The modern basin of trinational Lake Constance, between Switzerland, Germany, and Austria, represents the underfilled northern part of a glacially overdeepened trough. It is over 400 m deep and reaches well into the Alps at its southern end. The overdeepening was formed by the numerous glacial advance-retreat cycles of the Rhine Glacier throughout the Middle to Late Quaternary. A seismic survey of Lake Constance revealed a Quaternary sediment fill of over 150 m thickness under the modern lake floor in a maximal water depth of >250 m. This sedimentary sequence represents at least the last glacial cycle with ice-contact deposits at the base on top of the Molasse bedrock overlain by glaciolacustrine to lacustrine sediments. During the successful field test of a newly developed mid-size coring system ("HIPERCORIG"), the longest core ever taken in Lake Constance was recovered with an overall length of 24 m. The drill core, taken in a water depth of 200 m, consists of a nearly continuous succession of lacustrine sediments including over 12 m of pre-Holocene sediment at the base. The entire core was petrophysically and geochemically analyzed, sedimentologically described, and 14 lithotypes were identified. In combination with a <sup>14</sup>C- and OSL-based age-depth model, the core was divided into three main chronostratigraphic units. The basal age of ~13.7 ka BP places the base of the section back into the Bølling-Allerød interstadial whereas the overlying strata represent a complete Younger-Dryas and Holocene section.</p><p>The sediments offer a high-resolution insight into the evolution of Paleolake Constance from a cold postglacial to a more productive warm Holocene lake. The Late Glacial sections are dominated by massive, m-thick sand beds reflecting episodic sedimentation pulses. They are most likely linked with a subaquatic channel system that is still apparent in today's lake bathymetry despite the Holocene drape. This channel system was fed from a Late Glacial river from the north; provenance analysis of the initially unexpected sands together with hydrologic considerations will document whether this inflowing high-discharge river represented a local catchment (i.e. northern lake shore) or an Alpine signal (i.e. from the south) provided by the Rhine glacier. Tentative pore water hydrogeochemical and isotope analyses indicate a still active flow system at depth. The overlying Holocene section reveals a prominent, several cm-thick double-turbiditic event layer representing the most distal impact of the "Flimser Bergsturz", the largest known rock slide of the Alps that occurred over 100 km upstream the Rhine River at ~9.5 ka BP. Furthermore, lithologic variations in the Holocene section document the varying sediment load of the Rhine and of the endogenic production representing a multitude of environmental changes.</p>


The Holocene ◽  
2019 ◽  
Vol 29 (6) ◽  
pp. 992-1010 ◽  
Author(s):  
André-Marie Dendievel ◽  
Benjamin Dietre ◽  
Hervé Cubizolle ◽  
Irka Hajdas ◽  
Werner Kofler ◽  
...  

A paleoecological study (macrofossils, pollen, cryptogam spores, non-pollen palynomorphs) was performed to investigate environmental changes recorded on the peat deposits of the La Narce du Béage mire (Massif Central, France). We reconstructed the development of a limnogenous mire ecosystem during the Holocene, consequently to the infilling of a small Late Glacial lake. Successions from aquatic flora ( Isoëtes, Nitella opaca/ syncarpa, Botryococcus, Alisma plantago-aquatica, Potamogeton, Sparganium) to mire plant species ( Alnus glutinosa, Betula nana, Betula pubescens, Cyperaceae, Ericaceae, Sphagnum) underlined a gradual eutrophication and acidification during the lowering of the water table. We demonstrated a clear link between these local hydro-ecological changes and the early Holocene climatic warming. Also dealing with archeology, we provided key issues for the identification of human-induced environmental changes. Three phases of ecological disturbances with clearings of the mixed-oak forest and agro-pastoral activities were evidenced at 7700–7300, 6800–6420, and 5500–4250 cal. BP. Our results confirmed early Neolithic (Cardial influences), middle Neolithic (Chassean), and late Neolithic (Ferrières group) frequentations of the Béage Plateau, probably included in large-scale socio-cultural changes (SE France, NW Mediterranean Basin). Later, forest clearings (beech and fir), cultivation, and pastoralism were outlined since the Iron Age (after 2300 cal. BP, that is, 350 BC). Increasing human pressure was especially recorded during the last 1700 years, with rye ( Secale cereale) cultivation and extensive livestock grazing around and on the mire, which is nowadays a protected ‘Natura 2000’ area.


2018 ◽  
Vol 61 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Merlin Liiv ◽  
Tiiu Alliksaar ◽  
Leeli Amon ◽  
Rene Freiberg ◽  
Atko Heinsalu ◽  
...  

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