Palaeohydrological Changes Research Articles

Fluvial archive of peculiar avulsive fluvial patterns in the largest Quaternary intracratonic basin of tropical South America: The Bananal Basin, Central-Brazil

The Bananal Basin is the most important intracratonic Quaternary sedimentary basin of South America and preserves a good record of the paleohydrological conditions of Central Brazil at the Cerrado–Amazon ecotone. This area is currently a large tropical plain, seasonally flooded by rainfall and water table saturation that can be classified as a seasonal wetland.This paper presents a geological and geomorphological analysis supported with geochronological dating aiming to reconstruct the Pleistocene environmental history of the Bananal Basin. The basin was filled by the sediments sourced by the Araguaia–Mortes fluvial system. The deposits belong to the Araguaia Formation which covers ~106,000km2 of the Bananal Basin. TL and OSL chronologies of the Araguaia Formation show that sedimentation started at least in the Middle Pleistocene (MIS 7) but aggradation and avulsion processes were important in the Lower–Middle Pleniglacial between 70.5ka and 34.0±4.6ka (MIS 4 and 3) and in the Upper Pleniglacial between 24.5±3.1 and 17.2±2.3ka (MIS 2). River avulsions were more intense in the lower Bananal Basin (Bananal Island region). Remarkably, we did not record ages between 17ka and 10ka. Although avulsion seems to have been more active in the past, the abandonment by the Araguaia of a channel belt, now occupied by the underfit Javaés River, indicates that avulsion is still active. The avulsion processes are mainly related to palaeohydrological changes, although present-day seismic activity is also recorded.Additional data is needed to generate a more detailed scenario for the older Middle Pleistocene deposits. The data is remarkable, however, because it is the first Middle Pleistocene record described in a large alluvial tropical system in Brazil. The fluvial record is temporally in agreement with records from other large Brazilian fluvial systems such as the Amazon and Paraná basins. The Bananal plain, however, is unique because of its particular style of sedimentation and geomorphologic processes that generated a mega-scale anabranching-like complex pattern of paleochannels presently occupied by underfit streams.

Orbital imprint on Holocene palaeohydrological variations in west‐central Europe as reflected by lake‐level changes at Cerin (Jura Mountains, eastern France)

AbstractThis paper presents a lake‐level record for the Holocene at Lake Cerin (Jura Mountains, eastern France). It is based on a range of sedimentological techniques validated in previous studies, with a combination of systematic lithostratigraphic investigations of the infillings accumulated in the lacustrine basin, and sediment analyses of two selected cores. The chronology is based on 10 radiocarbon dates and pollen stratigraphy. On a millennial scale, the Cerin lake‐level record shows three distinct successive phases characterised by higher lake‐level conditions until ca. 9000 cal. a BP, followed by a maximal lowering at ca. 9000–8500 cal. a BP, and a progressive rise until the present. This rise was punctuated by centennial‐scale fluctuations, with major events around 4000, 2800 and after 1500 cal. a BP. Considered on a multimillennial scale, the general pattern of palaeohydrological changes reconstructed at Cerin reflects the impact of orbitally driven summer insolation. This is in agreement with other regional and extra‐regional palaeoclimatic records, although every record shows peculiarities in timing and shape depending on the proxy used for reconstruction. In this general context, centennial to multicentennial oscillations appear to have been second‐order events in comparison with the major influence of the orbital factor. Copyright © 2011 John Wiley & Sons, Ltd.

Analysis of fossil testate amoebae in Selisoo Bog, Estonia: local variability and implications for palaeoecological reconstructions in peatlands

Niinemets, E., Pensa, M. & Charman, D. J. 2010: Analysis of fossil testate amoebae in Selisoo Bog, Estonia: local variability and implications for palaeoecological reconstructions in peatlands. Boreas, 10.1111/j.1502-3885.2010.00188.x. ISSN 0300-9483. Local variability in decadal water-table changes on an ombrotrophic peatland was explored using testate amoebae analysis of near-surface peats in an Estonian raised bog. The distribution of testate amoebae assemblages was studied along the gradient from hummock to hollow in the upper 30-cm layer of peat. As expected, testate amoebae assemblages in different micro-ecotypes from hummock to hollow, even as close as 10 m apart, are distinctly different. Past water-table change was reconstructed by applying a transfer function based on modern samples from throughout Europe. Results show a decline in water level from the mid-late 20th century on Selisoo bog in all profiles from the different micro-ecotypes. However, the absolute water-table depths and amplitudes of fluctuations vary between reconstructions from different sampling micro-ecotypes. Cores were correlated using changes in non-mire pollen concentrations down-core, but it was not possible to correlate minor changes in water-table owing to non-contiguous sampling and variable accumulation rates. We conclude that different microtopes show the same decadal trends in relative water-table change but that the absolute magnitude of change may be more variable locally. It is important that reconstructed palaeohydrological changes in bogs consider changes in bog micro-ecotypes, and their variation over time, as this may alter the sensitivity of an individual record to drivers such as climate change. Comparison and compilation of data from parallel cores from different micro-ecotypes and/or different sites are likely to provide more robust reconstructions.

Late Quaternary palaeohydrological changes in the large playa Lake Frome in central Australia, recorded from the Mg/Ca and Sr/Ca in ostracod valves and biotic remains

The last 42,000 years of hydrological history of Lake Frome, a large playa located in the arid part of northern South Australia, which is hypersaline and most often dry today, is reconstructed using a combination of ostracod assemblages, other microfossil remains, and the trace elemental composition of the selected halobiont ostracod species of Diacypris and Reticypris. The Mg/Ca and Sr/Ca of ostracod valves from 2 cores relate to significant hydrological changes that affected the lake over time. The reconstruction of the Sr/Ca of the lake’s waters, based on the Sr/Ca of ostracod shells, shows that when the lake fills the waters originate mostly from runoff, not from hypersaline waters located below the lake or the surrounding aquifers. The Last Glacial Maximum saw gypsum deflation from the lake. Prior to 25K yBP, Frome had a stable hydrological regime, permanent water and low salinities, with occasional freshwater conditions between 42 and 33K yBP. From 25 to 20.3K yBP, salinities fluctuated and ephemeral conditions operated. After that, until ∼14.8K yBP, a brine pool was located below the lake and was therefore under a different hydrological regime. Between 13 and 11.2K yBP, wet conditions occurred, but such conditions were not seen again during the Holocene.

Late Quaternary palaeohydrological changes in the northern Namib Sand Sea: New chronologies using OSL dating of interdigitated aeolian and water-lain interdune deposits

Ephemeral rivers today terminate in playas adjacent to the eastern part of the Namib Sand Sea, although there is evidence that these fluvial systems penetrated further west in the past. There are water-lain sediments exposed in interdune areas of the northern Namib Sand Sea associated with the former course of the Tsondab River, which are central to palaeoenvironmental reconstruction in the region. These deposits indicate that there was increased moisture availability in this presently hyper-arid region and/or the catchments of the rivers to the east of the Sand Sea in the Great Escarpment. Until now the chronology for the deposition of these sediments has been based on radiocarbon ( 14C) dates on carbonate materials. The validity of these ages is problematic and 14C limits the timescale to which these sediments can be dated. The water-lain units are bracketed by aeolian sand units, which are highly suitable for optically-stimulated luminescence (OSL) dating. Here, 24 OSL ages from three sites associated with the former course of the Tsondab River are presented, allowing a reassessment of the timing of sediment deposits and the west to east progression of the terminus of the Tsondab River during the late Quaternary. Narabeb, which is 60 km north-west of the current end point of the Tsondab River at Tsondab Vlei, contains eight mud units, six of which are shown to be of marine oxygen isotope stage (MIS 5, 128–75 ka) age. Water-lain units at Hartmut Pan, 55 km north-west of Tsondab Vlei, are dated by OSL to between 16.9 ± 0.9 ka and 12.7 ± 0.1 ka. At Ancient Tracks, closest to the Tsondab Vlei (6 km west), mud units are younger, and placed between 12.0 ± 0.7 and 12.8 ± 0.8 ka, 11.5 ± 0.5–10.5 ± 0.5 ka and after 10.5 ± 0.5 ka. This new chronology is compared with other key regional records to identify potential regional relationships and forcing factors. There is greatest correspondence with the records in the north of the summer rainfall zone. A revision of both old and young 14C ages on carbonate materials calls for revision of other 14C chronologies in the region and highlights the problems with the continued used of histograms of 14C-ages to indicate periods of increased humidity in southern Africa.

Sphagnum δ13C values as indicators of palaeohydrological changes in a peat bog

Late-Holocene peat stratigraphy of a Canadian boreal peat bog was examined to evaluate the potential of Sphagnum δ13C values as surface moisture proxy indicators. Isotopic measurements were compared to testate amoebae-inferred water-table depth reconstructions, plant macrofossil assemblages and past decomposition levels inferred by colorimetric humification. AMS radiocarbon dates were coupled with 210Pb dates to establish peat chronology. Although the mechanisms underlying carbon fractionation processes in peatlands are not well understood, we demonstrate that Sphagnum δ 13C values have potential for palaeohydrological reconstructions, since variations presented by the isotopic values can generally be correlated with the other proxy records, especially during drier episodes.

Surface–bottom relationships in the Gulf of Salerno (Tyrrhenian Sea) over the last 34 kyr: Compositional data analysis of palaeontological proxies and geochemical evidence

The palaeontological, geochemical and mineralogical records of core GNS84-C106 were analysed in order to reconstruct palaeohydrological changes and palaeoproductivity patterns in the Gulf of Salerno for the last 34 kyr. This approach, including compositional analysis of planktonic and benthic assemblages, gave an insight into the relationships between continental, sea surface and bottom environmental changes. The main source of variability of planktonic and benthic assemblages is related respectively to sea surface temperature and palaeobathymetry. Interrelated changes in surface salinity, nutrients, density gradient in the water column and organic fluxes at the bottom act as a secondary factor controlling the composition of both planktonic and benthic assemblages. The highest palaeoproductivity rates were reached during an interval spanning from late glacial to Middle Holocene, in conditions of enhanced continental run-off. During the Early and Middle Holocene, reduced surface salinity and density stratification were also coupled with the development of a deep chlorophyll maximum and enhanced flux or organic matter at the bottom. From about 6.5 kyr B.P. onward, a sharp reduction in palaeoproductivity took place, coupled with an increase in surface salinities.

Is spontaneous regeneration of raised mire vegetation possible? A case study of the `Czarne Bagno' mire in the Bystrzyckie Hills, southern Poland

Research carried out at the `Czarne Bagno' raised mire in the Bystrzyckie Hills range of Poland's Sudety Mountains aimed to determine dynamic trends for the site's peatland vegetation. Present vegetation was therefore characterized. An analysis of plant macroremains from peat cores was used to reconstruct the identity of the past peat-forming plant communities. Several succession stages of vegetation from the time of origin of the peatland through to the present day were indicated on this basis. Ecological indicative values of plant species were also used to determine the palaeohydrological changes experienced. Stages of the development of the tree stand growing on the mire were established from dendrochronology series. Results obtained point to an interruption of the succession of primary vegetation on the peatland around 250 years ago, when today's sparse tree stand of rhaetic pine, Norway spruce and downy birch began to develop. Nevertheless, the last 50 years have brought a reversal of this developmental trend, with elements typical for raised mire returning and the tree stand in retreat. These phenomena seem to have coincided with the onset of peatland drainage, followed by a gradual overgrowing of drainage ditches and consequent re-raising of water level in the mire, respectively.

Holocene paleoclimatic and paleohydrological changes in Lake Balaton as inferred from a complex quantitative environmental historical study of a lacustrine sequence of the Szigliget embayment

The present paper discusses the findings of a complex quantitative paleoecological investigation implemented for capturing the Upper Weichselian, Late Glacial and Postglacial development of Lake Balaton in western Hungary, in the heart of Transdanubia. The studied Late Pleistocene and Holocene lacustrine marl and peat sequence preserved the complete evolutionary history of the catchment basin of the Szigliget Embayment from the time of its birth. The inferred palaeohydrological changes, along with that of the hydroseries, were compared to those observable coevally in the terrestrial vegetation. According to the available data, the birth of the studied embayment can be put to the Late Glacial/Upper Weichselian transition. A wide array of hydrophyte vegetation and habitat types emerged in the embayment depending on the actual water supply and geomorphologic position. Based on a collective quantitative evaluation of the observed sedimentary features and fossil assemblages retrieved from the sequence, a record of paleohydrological transformations in the littoral part of the lake was drawn.

Alluvial evidence for major climate and flow regime changes during the middle and late Quaternary in eastern central Australia

As a low-gradient arid region spanning the tropics to the temperate zone, the Lake Eyre basin has undergone gentle late Cenozoic crustal warping leading to substantial alluvial deposition, thereby forming repositories of evidence for palaeoclimatic and palaeohydrological changes from the Late Tertiary to the Holocene. Auger holes and bank exposures at five locations along the lower 500 km of Cooper Creek, a major contributor to Lake Eyre in the eastern part of the basin, yielded 85 luminescence dates (TL and OSL) that, combined wit a further 142 luminescence dates from northeastern Australia, have established a chronology of multiple episodes of enhanced flow regime from about 750 ka to the Holocene. Mean bankfull discharges on Cooper Creek upstream of the Innamincka Dome at 250–230 ka or oxygen isotope stages (OIS) 7–6 are estimated to have been 5 to 7 times larger than those of today, however, substantially less reworking has occurred during and after OIS 5 than before. Lower Cooper Creek appears to have similarly declined. In the Tirari Desert adjacent to Lake Eyre there is evidence of widespread alluvial activity, perhaps during but certainly before the Middle Pleistocene, yet the river became laterally restricted in OIS 7 to 5. While the Quaternary has been characterised by a dramatically oscillating wet–dry climate, since oxygen isotope stage OIS 7 or 6 there has been a general decline in the magnitude of the episodes of wetness to which the eastern part of central Australia has periodically returned. During the last full glacial cycle, Cooper Creek's periods of greatest runoff and sand transport were not during the last interglacial maximum of OIS 5e (132–122 ka) but later in OIS 5 when sea levels and global temperatures were substantially below those of 5e or today. Fluvial activity returned in OIS 4 and 3, but not to the extent of mid and late OIS 5; strongly seasonal but still powerful flows transported sand and fed source-bordering dunes in OIS 5 and 3. This chronology of fluvial activity in the late Quaternary broadly coincides with that for rivers of southeastern Australia and suggests that the wet phases in eastern central Australia have not been governed as much by the northern monsoon as by conditions in the western Pacific close to the east coast both north and south. Flow confinement within the Innamincka Dome has locally amplified Cooper Creek's energy, and here evidence exists for short but high-magnitude episodes of flow during the Last Glacial Maximum and in the early to middle Holocene, conditions that were capable of forming large palaeochannels but that were not long-lived enough to rework the river's extensive floodplains elsewhere along its length.

Palaeohydrological changes and human-impact history over the last millennium recorded at Lake Joux in the Jura Mountains, Switzerland

On the basis of sediment and pollen analyses of a radiocarbon-dated sediment sequence from Lake Joux in the Swiss Jura Mountains (west-central Europe), this paper presents a high-resolution record of lake-level and vegetation changes for the last millennium. The lake-level record makes it possible to determine that low-stands of the water-table dominated at c. AD 1200—1400, and from 1720 onward, with interruptions by short-lived rise events at c. AD 1340 and 1840. Highstands prevailed at c. AD 1100, and around AD 1450, 1550 and 1700. The comparison of the Joux lake-level record with a solar irradiance record based on cosmogenic nucleides supports the hypothesis of a major solar forcing of climate variations in west-central Europe over the last millennium. In agreement with other palaeohydrological records established in Western Europe and in the central North Atlantic Ocean, the Joux lake-level record suggests that, on a multicentennial scale, the period of the `Little Ice Age' coincided in the European mid-latitudes with wetter climatic conditions, and probably with an increase in summer precipitation. Variations in the hydrological cycle appear to have been associated with changes in the general atmospheric circulation pattern, probably coupled with variations in oceanic circulation and solar activity. The Joux record also points to changes in water resources expected to result from ongoing global warming. Finally, despite the severe climatic conditions which prevail in the Joux Valley, the human impact history at Lake Joux over the last millennium seems to reflect political choices and economic context more than climatic changes.

Early-Holocene climatic oscillations recorded by lake-level fluctuations in west-central Europe and in central Italy

On the basis of lake-level data, the period of the Preboreal oscillation (PBO) at 11 300–11 150 cal yr BP as defined by the GRIP oxygen-isotope record appears to correspond to wetter climatic conditions in west-central Europe and to a marked drying in north-central Italy. Additional short-lived phases of higher lake level have been identified before the PBO at ca 11 450–11 400 and 11 350 cal yr BP in west-central Europe, and at ca 11 500 cal yr BP in Italy. Such multiple climatic oscillations around the PBO have been observed in various records in northwestern Europe. On the basis of various proxies, a map of changes in moisture over western Europe during the PBO indicates a mid-latitude zone between 58 and 43°N characterised by wetter conditions, while a drier climate developed in southern and northern Europe. This wet middle zone shows a larger extension and suggests a more meandering, weaker Atlantic Westerly Jet during the PBO than during the 8.2 kyr event. A comparison of lake-level records in west-central Europe with (1) outbursts from North American and north-European proglacial lakes, and (2) variations in solar activity as reflected by 14C and the 10Be records supports the hypothesis that the PBO was a response to successive meltwater pulses at 11 300, 11 250, 11 200 and 11 170 cal yr BP and to a sudden decrease in solar activity at 11 250 cal yr BP. This study points to the necessity of developing integrated multi-proxy approaches to construct more robust regional event stratigraphies, and of better documenting palaeohydrological changes in the Mediterranean area.

Climatic and hydrological instability in semi-arid equatorial East Africa during the late Glacial to Holocene transition: A multi-proxy reconstruction of aquatic ecosystem response in northern Tanzania

This paper reports new multi-proxy palaeoenvironmental data on the late Glacial-Holocene transition (c. 14.8–9.3 ka) in equatorial East Africa, in the form of microfossil assemblages (chironomids, diatoms and ostracods) recovered from the sediment record of Lake Emakat, Empakaai Crater, northern Tanzania. In the context of available palaeoclimatic and palaeoecological information from the region and previously published fossil pollen and carbon and nitrogen isotopic data for the same sediment sequence, we here reconstruct local lake-system response to regional climatic and hydrological instability during the period of post-glacial warming. The aquatic biological proxy indicators suggest that the water level and chemistry of Lake Emakat evolved, first from a shallow freshwater body at 14.8 ka to a deeper freshwater phase between c.14.4 and 10.3 ka and then to a markedly shallower, alkaline-saline environment after c.10.3 ka. The lake appears to have been deepest between 13.2 and 12.0 ka, at a time of climatic drying when moist montane forest vegetation within the lake's crater catchment was being replaced by open wood-and scrubland. Some palaeohydrological changes reconstructed for Lake Emakat are in phase with lake evolution elsewhere in the region and thus apparently track broad-scale climate changes, but some are not. Collectively these multi-proxy paleolimnological data indicate a complex adjustment of the local aquatic ecosystem to temporal variations both in total annual effective precipitation and its seasonal distribution. The lake's hydrological response was further conditioned by local factors, notably its geological and topographic setting.

Mollusca stable isotope record of a core from Lake Frassino, northern Italy: hydrological and climatic changes during the last 14 ka

A core retrieved from Lake Frassino (northern Italy) provided evidence of palaeohydrological change in this area during the last 14 ka. Lithological, malacological and, in particular, stable isotope composition of freshwater shells allowed the delineation of the main phases of lake evolution between the Lateglacial and Holocene. Lateglacial conditions were drier than the Holocene, although a wetter period was inferred before c. 14 ka. According to the oxygen isotope composition of freshwater shells, the Holocene showed a clear bipartition. The first part, which lasted from ∼9100 to 7000 yr BP, was drier and was followed by a rapid increase in humidity at ∼ 7000-6800 yr BP. Between ∼ 6800 and 5000 yr BP, there were wetter and more stable conditions, as indicated by smaller δ18O oscillations of Pisidium and Valvata shells. From c. 5000 to 2600 yr BP the record is characterized by larger fluctuations, which may indicate that short-term and particularly pronounced alternation of wet and dry periods occurred.

Multiple phases of North African humidity recorded in lacustrine sediments from the Fazzan Basin, Libyan Sahara

The Fazzan Basin of south-west Libya is at present arid with less than 20 mm of rainfall per annum. However, regionally extensive limestones, lacustrine sands and coquina (fossiliferous carbonate rock) deposits show that the Fazzan Basin previously contained a large palaeolake, indicating that the climate in the past was more humid. Optically stimulated luminescence (OSL) dating techniques have been applied to key lacustrine deposits within the basin in an attempt to provide an internally consistent chronology for this humidity record. Results indicate that palaeolake sediments within the Fazzan Basin record a very long history of palaeohydrological change, ranging from present day arid conditions to humidity capable of sustaining a lake with an approximate area of 76,250 km 2. The existence of humid periods in mid oxygen isotope stage 5 and the early Holocene is confirmed. An older lacustrine event, tentatively correlated to oxygen isotope stage 11, is also recognized. In addition, evidence is presented for at least two humid phases beyond the age range over which the conventional OSL dating technique is applicable. This study demonstrates that OSL dating of palaeolake sediments within the Fazzan Basin offers the potential to provide a detailed record of North African humidity spanning several glacial–interglacial cycles.

Testing the relationship between Holocene peatland palaeoclimate reconstructions and instrumental data at two European sites

Peatland surface wetness records provide long Holocene palaeoclimate reconstructions at 10 1–10 2 year resolution. They reflect changes in water balance but the relative strength of precipitation and temperature signals are not known. In common with other non-annually resolved records, there has been no testing of the reconstructions against instrumental climate data. In this paper high-resolution records of palaeohydrological change reconstructed from testate amoebae analysis are used to examine critically the relationships between reconstructed water table change, instrumental water table and climate data. A 200-year record of reconstructed water table from northern England shows that the strongest control on reconstructed mean annual water table change is summer precipitation, with summer temperature becoming more important over longer time periods. A 50-year record from Estonia shows that both measured and reconstructed water table records are strongly correlated with summer precipitation. Summer temperature is also correlated with reconstructed water table. We conclude that peatland surface wetness records should be interpreted as primarily reflecting summer precipitation variability, with summer temperature increasingly important in more continental settings.

Changements hydrologiques holocènes enregistrés sur le site de la station IX du grand lac de Clairvaux (Jura, France) [Reconstruction of holocène palaeohydrological changes at station IX, grand lac de Clairvaux (Jura, France)

Trenches excavated for the construction of a camping place on the south-eastern shore of the grand lac de Clairvaux have given the opportunity to observe and sample a sediment sequence documenting lake-level changes from 6300 to 1500 14C yr BP It shows an alternation of peaty layers corresponding to low lake levels at ca 63 10, 4925, 4585-3520, 3000-2885, 21 10 et 1680-1475 14C yr BP, and carbonate deposit layers recording high lake levels. These lacustrine carbonate sediments also include allochthonous detritic components suggesting, that the phases of higher lake level coincided with an increase in run-off and erosion processes on the slopes surrounding the lake. The palaeohydrological changes reconstructed at station IX agree with the regional phases of changes in lake level defined from lake sediment-sequences in the Jura mountains, the northern French Pre-Alps and in the Swiss Plateau.

Lake-Level fluctuations at Le Locle, Swiss Jura, from the Younger Dryas to the Mid-Holocene: A high-resolution record of climate oscillations during the final deglaciation

On the basis of a high-resolution (10 cm / 110 years) lacustrine sequence from Le Locle, Swiss Jura, a fine-scale pattern of palaeohydrological changes is reconstructed for the late Younger Dryas (YD) and the early to mid-Holocene period. The late YD is characterized by a general trend of a fall in lake level and a large climatic instability. The early to mid-Holocene period shows a quasi-cyclic pattern of lake-level fluctuations. Large drops in lake level occurred at ca. 11 600-10 200 cal. BP and ca. 8 900-7 700 cal. BP. Each was interrupted by a short-term rise in lake-level and followed by a longer phase of high lake level respectively at ca. 10 200-8 900 cal. BP and ca. 7 700-6 600 cal. BP. The high lake-level periods at le Locle appear to be in phase with cold spells reconstructed in central Europe, in eastern North America and in the Greenland ice-sheet, or with cooling events and salinity anomalies recorded in the North Atlantic zone. They also coincide with rising residual Δ14C values. These data and the Lateglacial oxygen-isotope GISP2 record suggest three successive quasi-cycles of climatic and environmental changes showing strong similarities in their internal structure. These cycles suggest that large-scale climate oscillations developing from the Bølling warming to the mid-Holocene could have been associated with changes in ocean ventilation probably induced by three deglaciation steps. Finally, as a working hypothesis, a re-exami- nation of the YD event is proposed from a Holocene point of view.

Palaeohydrological changes as reflected by lake-level fluctuations in the Swiss Plateau, the Jura Mountains and the northern French Pre-Alps during the Last Glacial–Holocene transition: a regional synthesis

This paper presents Lateglacial and early Holocene lake-level fluctuations reconstructed from a sedimentary approach of cores from Gerzensee and Horgen-Scheller, Zürichsee, in the Swiss Plateau, and Sevrier, Lake Annecy, in the northern French Pre-Alps. Then, these data are integrated with lake-level records previously established at Montilier, Lake Morat (Swiss Plateau) and Le Locle (Jura) to build a first tentative stratigraphy of palaeohydrological events for the period 15–11 ka cal. BP in the Swiss Plateau, the Jura Mountains and the northern French Pre-Alps. Correlations between the lake-level records are based on AMS radiocarbon dates, pollen and isotope stratigraphy and tephrochronology (Laacher See Tephra). Then, this regional palaeohydrological event stratigraphy is compared with the GRIP oxygen-isotope record and the event stratigraphy scheme based on this record. The phases Greenland Interstadial (GI) 1e, GI-1c, GI-1a, the middle GS-1, the Greenland Stadial (GS) 1–Preboreal transition and the period following the Preboreal oscillation (PBO) coincide with low lake-level conditions. However, phases GI-1d, GI-1b, the early and late GS-1 and the PBO correspond to higher lake-levels. These correlations highlight the palaeohydrological significance of the climatic events associated with the Last Glacial–Holocene transition in the European mid-latitudes.

Book Review: Palaeohydrology and environmental change.

Book Review: Palaeohydrology and environmental change.