Eemian Site Research Articles

The northernmost Polish Eemian palaeolake near Łęczyce − Stratigraphic and palaeoecological implications for a MIS 6a − MIS 5d sediment record

We report the results of high-resolution multi-proxy studies of a 10 m thick sedimentary profile from Łęczyce, Poland. It reveals a continuous lacustrine succession from the Eemian Interglacial. On this basis, we have distinguished seven sedimentary units (U7a-U7f) and ten local palynological zones (LPAZ Lec 1 − Lec 10), revealing the evolution of the lake from the moment of dead-ice melting, through the continuous filling of the lake basin with organic mud, to the final stage of shallowing and transformation into a peat bog. This northernmost known Eemian site was investigated for the first time, therefore, the reconstructed changes in local conditions were correlated with global changes from the final phase of the penultimate glaciation through the Eemian Interglacial to the beginning of the last glaciation. The results show that the melting of dead ice blocks at this site was delayed compared to central Poland, with lacustrine processes starting as glaciolimnic sedimentation. Furthermore, the delayed start of vegetation development around the lake resulted in the absence of a Pinus-Betula-Ulmus E2 level. During the Eemian, local conditions were generally stable, and sedimentation took place in a relatively deep basin with well-defined epilimnion and hypolimnion zones. Climatic instability at the end of the Eemian resulted in reduced vegetation cover. During the first climatic deterioration in the Weichselian (presumably the Herning Stadial), lacustrine sedimentation was reduced and the deposition of fine-grained mineral material predominated. This was followed by the complete drying out of the lake and the development of soil formation. The subsequent climatic warming (Brørup Interstadial?) recorded in the uppermost part of the profile (U7f) was characterised by the plant community Lec 10 (Carpinus-Corylus-Picea) and was presumably warmer than commonly assumed. Multi-proxy studies show that the development of the lake was more similar to that of southern Scandinavia than to that of Poland.

Malacological data from the eemian site at waziers (scarpe plain, northern France)

Malacological data from the eemian site at waziers (scarpe plain, northern France)

Eemian to Early Weichselian regional and local vegetation development and sedimentary and geomorphological controls, Amersfoort Basin, The Netherlands

Abstract Two new records from the Amersfoort glacial basin are investigated by means of pollen analysis. The cores are situated in the deeper part, close to the original Eemian stratotype Amersfoort 1 (Zagwijn, 1961) and at the margin of the basin. The aim is to reconstruct the Eemian and Early Weichselian vegetation development and to explore the impact of accommodation space, influx of allochthonous pollen and geomorphology on the vegetation composition. The results of the Amersfoort Basin are compared to the current Eemian stratotype in the Amsterdam Basin and other Eemian sites in the Netherlands. An almost complete Eemian to Early Weichselian sequence (E2-EWII) was retrieved from the deeper part of the Amersfoort basin. The late Saalian (LS) to early Eemian transition is not recorded in the Amersfoort basin, in contrast to the deeper Amsterdam Basin. The basin marginal core Den Treek reveals a condensed late Eemian (E5-6) and Early Weichselian (EW I-II) succession showing the importance of accommodation space. The first impact of the Eemian transgression is registered at the E3 to E4a boundary in the Amersfoort and Amsterdam basins, and highest sea level is proposed at the end of pollen zone E5. Upstream in the Eemian delta, in the palaeo-Vecht valley and IJssel Basin, the transgression is recorded later. The influx of reworked (allochthonous) pollen in clastic sediment units hampers vegetation and climatic reconstructions during the LS and Eemian. The early appearance of Picea in zone E4 and Abies in zone E5 in clastic sediment intervals can be related to long-distance transport by the river Rhine and redistribution in the Eemian delta. Local vegetation development can complicate regional biostratigraphic correlations. Alnus, considered characteristic for the late Eemian (E5-6), shows large differences over short distances in the Amersfoort Basin, related to local alder growth since Eemian E3. Carpinus, diagnostic for pollen zone E5, shows high values in the basins adjacent to higher, well-drained ice-pushed ridges, but low values in low-relief environments. Salt- to brackish-water marshes were present during high sea level in zone E5 in the Amsterdam and Amersfoort basins, while further upstream in the Rhine delta brackish to fresh-water tidal conditions dominated. In line with Zagwijn (1961), the E6 to EWI boundary is defined at the first opening of the vegetation cover with Calluna, Poaceae and Artemisia increase, often coinciding with a lithological change from organic to clastic deposition, reflecting increased landscape instability. The cores from the Amersfoort basin reveal a complete Eemian to Early Weichselian record. It is suggested to define the boundary stratotype for the base of the Weichselian Stage in the Amersfoort Basin. The current stratotype Amsterdam-Terminal reveals a fully developed LS to Eemian transition and contains the boundary stratotype for the base of the Eemian Stage.

Eemian landscape response to climatic shifts and evidence for northerly Neanderthal occupation at a palaeolake margin in northern Germany

AbstractThe prevailing view suggests that the Eemian interglacial on the European Plain was characterized by largely negligible geomorphic activity beyond the coastal areas. However, systematic geomorphological studies are sparse. Here we present a detailed reconstruction of Eemian to Early Weichselian landscape evolution in the vicinity of a small fingerlake on the northern margin of the Salzwedel Palaeolake in Lower Saxony (Germany). We apply a combination of seismics, sediment coring, pollen analysis and luminescence dating on a complex sequence of colluvial, paludal and lacustrine sediments. Results suggest two pronounced phases of geomorphic activity, directly before the onset and at the end of the Eemian period, with an intermediate period of pronounced landscape stability. The dynamic phases were largely driven by incomplete vegetation cover, but likely accentuated by fluvial incision in the neighbouring Elbe Valley. Furthermore, we discovered Neanderthal occupation at the lakeshore during Eemian pollen zone (PZ) E IV, which is chronologically in line with other known Eemian sites of central Europe. Our highly‐resolved spatio‐temporal data substantially contribute to the understanding of climate‐induced geomorphic processes throughout and directly after the last interglacial period. It helps unraveling the landscape dynamics between the coastal areas to the north and the loess belt to the south.

Palaeobotanical record of the Eemian Interglacial succession at the Jagodne site (Garwolin Plain, central Poland)

Our high-resolution data of pollen and macrofossils from 2 cores taken from the Jagodne site (Garwolin Plain) reveals a pollen succession covering the final part of the Late Saalian (Marine Isotope Stage MIS 6) and embracing the Eemian (MIS 5e). The results correspond to Regional Pollen Assemblage Zones (RPAZ). The hornbeam phase (E5 RPAZ) has been subdivided into subzones and compared to the corresponding division of the key profile of the Garwolin Plain, Kozłów K2-19. The comparison revealed a considerable sedimentary hiatus in the E5 RPAZ at Jagodne. This is attributed to significant palaeohydrological changes occurring widely in this zone, and also seen at other Eemian sites in Poland. Another specific feature of the Jagodne site is the early, rapid terrestrialisation of the palaeolake and its transformation into a raised bog, which occurred already at the end of the hornbeam phase. The Sphagnum dominated peatbog developed for a long time as evidenced by a thick peat layer covering also the Early Vistulian. Both pollen and plant macrofossil data correspond well to observed lithological boundaries, providing a consistent record of palaeoenvironmental and palaeoclimate changes. The results obtained contribute to knowledge of palaeoenvironmental changes and palaeoclimate interpretation of that area.

Chironomid-based temperature reconstruction for the Eemian Interglacial (MIS 5e) at Sokli, northeast Finland

The Last Interglacial (Eemian, MIS 5e) can be considered a test-bed for climate dynamics under a warmer-than-present climate. In this study we present a chironomid record from the high latitude Sokli site (N Finland), where a long continuous sediment sequence from the last interglacial has been preserved from glacial erosion. The chironomid-analysis shows a diverse fauna, with dominance of warm-water indicators and shifts in assemblage composition that can be attributed to temperature, lake depth, productivity and habitat availability. Quantitative mean July paleotemperature estimates based on the chironomid data indicate overall mean July air temperatures up to 1 °C warmer than present. Two cooling events can be discerned, the Tunturi event, dated to about 127.5 ka BP, in the lower part of the sequence, and the Värriö event, dated to about 119 ka BP, associated with the beginning of a cooling trend in the upper part of the record. Warm conditions already at the onset of the interglacial contrast with a recent chironomid-based last interglacial temperature reconstruction from Denmark, which suggests a late onset of Eemian warming. The relatively small increase in inferred temperatures compared to present day temperatures at Sokli differs from other high latitude Eemian sites, and likely reflects the influence of the Atlantic Meridional Overturning Circulation in maintaining already elevated temperatures in Fennoscandia during interglacials.

Palaeoenvironmental and climate changes recorded in the lacustrine sediments of the Eemian Interglacial (MIS 5e) in the Radom Plain (Central Poland)

The Radom Plain is a region with numerous fossil palaeolakes that formed a palaeolakeland. Lacustrine sediments of thickness varying from 0.5 to 18 m were encountered in numerous boreholes. Pollen analyses of the sediments filling the palaeolakes have proven that their sedimentation began after the retreat of the Saalian ice-sheet (MIS 6), continued during the Eemian Interglacial (MIS 5e), and terminated at the beginning of the Weichselian Glaciation (MIS 5d). Climate and palaeoenvironmental changes have been recorded in different deposits: muds, peats and gyttja. Local factors, such as reservoir depth, and geological conditions have influenced the type of the accumulated sediments. Eemian sites occur in two geomorphological positions: in small depressions on the glacial plateau and in small valleys in ox-bow palaeolakes. Eemian lakes were formed from the melting of dead-ice blocks. Pollen data obtained from the palaeolake sediments document climate and vegetation changes characteristic of the Late Glacial period, the Eemian Interglacial, and the beginning of the Weichselian Glaciation. In many sites, a record of a complete Eemian succession is present, whereas in others it is fragmentary. Comparison of pollen data between the Radom region and other localities in Poland shows local and regional differences in the development of forest communities in the Eemian. In the Eemian sequences of the Radom Plain, a considerable contribution of Tilia, Picea and Abies pollen is distinct in the forest communities, often higher than in other Eemian sites of Central Poland. The particularly high percentage of Tilia (exceeding 30%), Picea (up to 67%) and Abies (30%) pollen are recorded in the Babin site. This phenomenon may indicate favourable environmental and climate conditions, facilitating further propagation of these trees. In the pollen record from the Babin site, three distinct abrupt/cool climate oscillations have been noted, with the oldest one recorded in the Saalian Glaciation. The two younger oscillations have been distinguished at the very beginning and at the very end of the Last Interglacial, respectively. Eemian sites from the Radom Plain are important for the reconstruction of palaeoenvironmental and palaeoclimate changes in the Eemian Interglacial in Poland and Europe.

Semi-open environmental conditions during phases of hominin occupation at the Eemian Interglacial basin site Neumark-Nord 2 and its wider environment

Neandertal occupation of Eemian environments in Europe is well attested by several archaeological sites dating to this interglacial period. Does this mean that Neandertals were living in closed forest environments? Due to the potential variability of Eemian environments in space and time, it is necessary to study environmental records that can be correlated with phases of hominin presence, as reflected in the archaeological record. Such a perspective can be obtained from the small basin locality Neumark-Nord 2, as it contains an extensive and detailed environmental record, as well as a large archaeological record consisting of several distinct find levels. Analysis shows that hominin presence is predominantly associated with semi-open environmental conditions. A review of the data from the neighbouring Neumark-Nord 1 basin shows that semi-open environments were also characterizing the wider environment during phases of hominin presence at both basin localities. Large herbivores attracted to the water in these basins may have played an important role in the vegetation openness, probably in conjunction with (local) climatic conditions. The relationship between hominin presence and semi-open environments is explained as Neandertals exploiting the large herbivores aggregating around these freshwater localities, while the more varied vegetation would also have provided them with edible plant foods. Other Eemian sites from freshwater contexts provide evidence for semi-open conditions as well.

Cyclicity in the Eemian climate? A case study of the Eemian site at Czaple, Eastern Poland

The newly discovered lacustrine deposits from Czaple, Eastern Poland, examined by means of pollen analysis, revealed an undisturbed, continuous sequence of vegetational development of the Eemian/Early Vistulian age. We tried to trace the secondary climatic trends, cyclic in part on the basis of plant taxa — representing the second league in the spectra, as to frequency, but forming an important group of the index plants. Their appearance becomes more pronounced and reliable when extraordinarily high numbers of pollen are analyzed. The oscillations of curves of these taxa are more clearly expressed than by traditional counts, revealing the hidden picture in the palynological background. It is interesting that some taxa – e.g. Hedera – form a distinctive intermittent pattern reflecting cyclicity of climatic condition or additional factors which are responsible for it. Pollen curves of other index plants do not show such regular variation. This cyclicity can be traced in many European Eemian diagrams. Especially interesting is the sudden decline of ivy as well as of other indicator plants in the subzone E4b such as the Corylus which marks some increase in a continentality of climate. We can also trace this trend in other sequences. In addition, extra counts allow us to estimate the exact timing of the migration of rarely noted exotic taxa and their range of distribution in the sequence. Buxus, Osmunda cinnamomea and Lycopodium lucidulum types are the best examples illustrating this.

A few prospective ideas on climate reconstruction: from a statistical single proxy approach towards a multi-proxy and dynamical approach

Abstract. Important progresses have been made in palaeoclimatological studies by using statistical methods. But they are in somewhere limited as they take the present as an absolute reference. This is particularly true for the modern analogue technique. The availability of mechanistic models to simulate the proxies measured in the sediment cores gives now the possibility to relax this constraint. In particular, vegetation models provide outputs comparable to pollen data (assuming that there is a relationship between plant productivity and pollen counts). The input of such models is, among others, climate. The idea behind paleoclimatological reconstructions is then to obtain inputs, given outputs. This procedure, called model inversion, can be achieved with appropriate algorithms in the frame of the Bayesian statistical theory. But we have chosen to present it in an intuitive way, avoiding the mathematics behind it. Starting from a relative simple application, based on an equilibrium BIOME3 model with a single proxy (pollen), the approach has evolved into two directions: (1) by using several proxies measured on the same core (e.g. lake-level status and δ13C) when they are related to a component of the vegetation, and (2) by using a more complex vegetation model, the dynamic vegetation model LPJ-GUESS. Examples presented (most of them being already published) concern Last Glacial Maximum in Europe and Africa, Holocene in a site of the Swiss Jura, an Eemian site in France. The main results are that: (1) pollen alone is not able to provide exhaustive information on precipitation, (2) assuming past CO2 equivalent to modern one may induce biases in climate reconstruction, (3) vegetation models seem to be too much constrained by temperature relative to precipitation in temperate regions. This paper attempts to organise some recent ideas in the palaeoclimatological reconstruction domain and to propose prospectives in that effervescent domain.

Oceanography in northwestern Europe during the last interglacial from intrashell δ 18O ranges in Littorina littorea gastropods

Coastal sea-surface temperature (SST) and sea-surface salinity (SSS), including seasonality, in northwest (NW) Europe during the early phase of the Eemian interglacial ca. 125 ka ago were reconstructed from Littorina littorea (common periwinkle) gastropods. The results were based on intra-annual δ 18O analyses in recent and fossil shells, mainly originating from the sea of Kattegat (Sweden) and the English Channel (United Kingdom), and confined to intertidal settings. The Eemian L. littorea shells indicated annual SSTs in the range 8–18°C for the English Channel and 8–26°C for Kattegat. All specimens from the Eemian sites experienced summer SSTs of ca. 1–3°C above recent conditions. The estimated winter SST in the English Channel during the Eemian was comparable to modern measurements of ca. 8°C. However, the Kattegat region displayed Eemian winter SST approximately 8°C warmer than today, and similar to conditions in the western English Channel. The recent-fossil isotope analogue approach indicated high SSS above 35 practical salinity units (psu) for a channel south of England in full contact with the North Atlantic Ocean during the last interglacial. In addition, the Kattegat shells indicated a SSS of ca. 29 psu, which points out a North Sea affinity for this region during the Eemian.

Optical dating of an Eemian site in Northern Russia using K-feldspar

Some published studies present evidence that quartz OSL dating of low ( ∼ 1 – 2 Gy / ka ) dose rate material may underestimate the true age of a deposit by ∼ 10 – 15 % at ∼ 130 ka or for D e values of ∼ 150 – 200 Gy . It is well known that feldspar IRSL grows to much higher doses than quartz and thus has the potential of performing better in this age range. In this paper we report on our continuing testing of the accuracy of K-feldspar IRSL dating with anomalous fading correction on known-age Eemian ( ∼ 125 – 130 ka ) material from northern Russia. Using a SAR IRSL protocol the luminescence characteristics of our samples are first documented and D e values and fading rates ( g values) measured. A single site-averaged fading rate of 3.26 ± 0.09 % / decade ( n = 80 ) is obtained and this value used to correct the optical ages. We compare the fading corrected IRSL ages with the known age of the deposits and with the results from a similar study on known-age Eemian material in Denmark. Finally, we discuss which dosimeter (K-feldspar or quartz) is preferred for this type of material.

Isotope and Cladocera data and interpretation from the Eemian optimum and postoptimum deposits, Kaliska palaeolake (Central Poland)

During the Eemian optimum, calcareous gyttja and lake marl accumulated. The characteristic feature of calcareous gyttja is an occurrence of fragments of diatoms and plants, while in lake marl they are absent. In the carbonate-rich deposits no Cladocera remains are preserved. Based on the results of stable isotope analyses of carbonates, the eight isotopic horizons (Is) were defined and characterised. In the studied deposits, 15 species of subfossil Cladocera were identified and 6 zones of fauna development were distinguished. The defined Cladocera species are similar to ones known from the other Eemian site in Poland. The faunal taxa indicate the low trophy status of the lake initially, followed by an increase to eutrophic status. The Cladocera and isotopic compositions suggest that the hornbeam zone (E5) was a period of higher density of macrophytes as well as of an increase of biological activity associated with the low water level. The fluctuations of the isotopic curves caused by a shallowing of the basin and a change of sediment lithology are characteristic for the spruce zone (E6). The palaeolake transformed into a peatbog during the pine zone (E7). During the Early Vistulian renewed carbonate accumulation and Cladocera development took place indicating the repeated reservoir existence.

Testing the accuracy of quartz OSL dating using a known-age Eemian site on the river Sula, northern Russia

Quartz optically stimulated luminescence (OSL) forms the basis for the chronology of Weichselian ice advances in Arctic Eurasia developed over the last few years. There is almost no age control on this chronology before 40 ka, except for some marine sediments correlated with marine isotope stage (MIS) 5e on the basis of their palaeofauna. Results from more southern latitudes have shown that dose estimates based on quartz OSL and the single aliquot regenerative (SAR) dose procedure may underestimate the age of MIS 5e deposits. Here we use the same method to date well-described marine sediments, thought to have been deposited during the very beginning of the Eemian interglacial at ∼130 ka, and exposed in two sections on the river Sula in northern Russia. Various quality-control checks are used to show that the OSL behaviour is satisfactory; the mean of 16 ages is 112±2 ka ( σ=9 ka). This represents an underestimate of ∼14% compared to the expected age, a discrepancy similar to that reported elsewhere. In contrast to SAR, the single aliquot regeneration and added (SARA) dose procedure corrects for any change in sensitivity during the first OSL measurement. The SARA results are shown to be ∼10% older than those from SAR, confirming the geological age estimate and suggesting that SAR ages may underestimate older ages (larger doses), despite their good performance in the younger age range.

Geochronology and palaeoenvironment of marine Quaternary deposits in Denmark: new evidence from northern Jutland

The degree of isoleucine epimerization in the benthic foraminiferal species Elphidium excavatum and Bulimina marginata have been measured in four boreholes, penetrating marine interglacial beds, from northern Jutland. The results of these analyses are compiled with results obtained from other sites in Denmark and the North Sea region, and four aminozones (AZs) have been erected. AZ1 (aIle/Ile < 0.05) include the Late Weichselian and the Holocene part of the record. AZ2 (0.08–0.12) includes samples of last interglacial age. AZ3 (0.14–0.16) includes samples from sites that have been previously correlated with the Holsteinian, and marine isotope stage 7 age for this zone is suggested. An age close to 400±100 ka is assigned to AZ4 (0.21–0.26). AZ4 is recorded in corings at Skagen and Nørre Lyngby, and includes the here defined Skagerrak Interglacial, which is tentatively correlated with marine isotope stage 11.The Skagerrak Interglacial sediments are characterized by boreal lusitanian benthic foraminiferal faunas evidencing strong input of Atlantic water to the North Sea. These faunas are replaced by assemblages indicating cooler conditions at least twice during this period. The sedimentation pattern in northern Jutland during this interglacial seems to be different from the sedimentation regimes in the same area at the classical Eemian sites and during the Holocene, which were characterized by large sediment input from the Jutland Current. This difference may be attributed to a change in the geometry of the sedimentary basin through the later part of the Quaternary, which is a result of repeated periods of intense erosion in the confluence area of the Norwegian Channel ice stream. A strong influx of Atlantic water to the North Sea during stage 11 has been suggested earlier, based on records from the Devil's Hole area. However, the correlation of this event to the classic biostratigraphic based schemes of northwest Europe is still problematic.

Amino acid geochronology of selected interglacial sites in the North Sea area.

Isoleucine epimerization (alle/Ile) ratios have been measured on foraminiferal tests from interglaical sites in the southern North Sea region. In order to evaluate the possibilities of this amino acid method on benthic foraminifera, sites were chosen from areas where the stratigraphy was already well known. The study demonstrates that the isoleucine epimerization reaction in benthic foraminifera can be used for correlation and as a means of relative age estimation within a limited geographic area. Previous suggestions of a Holsteinian age for the Rugȧrd, Tornskov, and Wacken sites are supported for the Kås Hoved site. The age of most presumed Eemian sites is supported by the amino acid results; the Reighton site also seems to belong in this interglacial.

Aminostratigraphy of European marine interglacial deposits

Molluscan fossils collected from shallow water marine sediment across NW Europe and nearby Arctic regions have been analysed for the extent of isoleucine epimerization (DL ratio) in indigenous protein residues. The DL ratios confirm that essentially all ‘classical’ Eemian sites from NW Europe are of the same age, and are correlative with the type locality near Amersfoort in the Netherlands; shells from interglacial marine sediment beneath the type Weichselian till in Poland also correlate with the type Eemian site. DL ratios in Holsteinian marine shells (0.29) are substantially higher than in their Eemian counterparts (0.17); ‘Late Cromerian’ shells yield even higher ratios (0.46). DL ratios in late glacial shells (0.06) and Middle Weichselian shells (0.09) permit differentiation from modern (0.01) and last interglacial material. Based on the position of the Matuyama-Brunhes boundary and the differences in DL ratios, the Eemian must correlate with isotope substage 5e, whereas the Holsteinian is most likely substage 7c, possibly stage 9 but certainly younger than stage 11. Intra-Saalian warm periods may be terrestrial equivalents of the younger substages of stage 7. Extensive pre-Eemian marine sediments along the SW coast of Denmark previously correlated with the Holsteinian are shown to be of ‘Late Cromerian’ age. The underlying till there is the first widespread evidence of a pre-Elsterian till in NW Europe.DL ratios in molluscs from last interglacial sites along the Arctic coast of the USSR, the Arctic Islands and eastern Greenland are substantially lower than in their European counterparts due to their low thermal histories. The combined mid- and high-latitude data are used to develop a predictive model for the expected DL ratio in any of several moderate epimerization-rate taxa for last interglacial sites with mean temperatures between −20 and +15°C.Not all sites could be unambiguously assigned to an established interglacial. The Fjøsanger (Norway) and Margareteberg (Sweden) sites previously thought to be Eemian, yield DL ratios higher than in secure nearby Eemian material. It is yet unresolved whether these are aberrant sites or if they predate the last interglacial. In situ shoreline deposits encountered in borings in SW Belgium and in exposures on the Belgium coastal plain contain molluscs that yield DL ratios intermediate between secure Eemian and Late Weichselian ratios, raising the possibility that a late stage 5 high-sea-level event attained near-modern levels in the southern North Sea basin. Resolution of these uncertainties is the focus of future work.