MIS 5c Research Articles

Ostracod-based palaeotemperature reconstructions for MIS 11 human occupation at Beeches Pit, West Stow, Suffolk, UK

The Mutual Ostracod Temperature Range (MOTR) method is applied to ostracod assemblages from the well-documented Middle Pleistocene (MIS 11) human occupation site of Beeches Pit, West Stow, Suffolk, England. The results provide palaeotemperature reconstructions which are compared against other proxy data from molluscs and ostracod indicator species. Ostracod assemblages from the lower part of the sequence (Beds 3 and 4) suggest a temperate climate with mean monthly temperatures (January and July) not dissimilar to those of today, while those of the overlying Bed 7 indicate a climatic shift to a more continental climate with winter temperatures at least 4 °C colder than today. These results corroborate previous suggestions that the evidence of human occupation at Beeches Pit occurs not only in the interglacial (MIS 11c) but also in a succeeding cold phase (possibly MIS 11b) and provide the first quantitative palaeotemperature reconstructions for this site and interval.

Natural environment of MIS 5 and soil catena sequence along a loess slope in the Seret River valley: Evidence from the Pronyatyn Palaeolithic site (Ukraine)

The Middle Palaeolithic site in Pronyatyn village is situated on the Ternopil Plateau, on the eastern, long and straight slope of the Krucha Gora hill (369.5 m a.s.l.). The structure of loess cover in this area was investigated in the series of archaeological excavations to a depth of 5–6 m in 1977–1985, 2010 and 2011. Lithological, palaeomagnetical and palynological analyses, as well as TL dating were carried out in the selected profiles. In all profiles, under thin cover of loess from the last aeolian deposition sub-cycle (MIS 2), a set of soils of S1 = Gorohiv s.l.; (MIS 5 complex) exists. This complex is composed of interglacial and interstadial units. Forest and forest-steppe vegetation, followed by a rich steppe with the continuous occurrence of trees and shrubs and without subarctic elements, developed during the stages of its formation. Based on the investigations of loess cover carried out over a large area, it was found that all sequences are spatially diversified in the profiles located along and across the slope in the middle part of this area. This diversity resulted from the development of pedogenetic and slope processes, depending on morphological features of individual slope segments. In the southern part of the study area, outside the extent of artifact occurrence, the deposits representing MIS 5 are undisturbed or slightly disturbed and contain a loess-soil sequence, which is composed of the interglacial Cambisol (with evidence for the Blake palaeomagnetic event) and 2–3 interstadial soils. Artifacts were discovered in the northern and northwestern parts of the study area, within a solifluctionally redeposited chernozem occurring on a denuded Luvisol. Based on the analysis of the artifact collection, the flint industry is the Western-Podolian, Levallois, radial-parallel, flakes-and-blades, without two-sided tools and with domination of knife-like products on Levallois blanks. This suggestion of the flint industry age as within the younger part of MIS 5 is supported by TL dates. It is most possible that this settlement took place in MIS 5c. Based on spatial distribution of artifacts, state of their preservation, and the features of solifluction deposits representing the younger part of MIS 5, we conclude that the site was originally located on the slope above the excavation area, about 30–50 m to the west.

First recorded evidence of subaqueously-deposited late Pleistocene interstadial (MIS 5c) coastal strata above present sea level in Australia

Abstract Significant differences in the elevation of late Pleistocene interstadial coastal strata have been noted at the global scale resulting from the combined effects of tectonism, proximity of field sites to Pleistocene ice sheets, and the variable effects of glacio-hydro-isostatic adjustment processes. Here we report the first recorded example of subaqueously deposited late Pleistocene interstadial coastal sediments above present sea level in Australia, in a far-field location to Pleistocene ice sheets and characterised by minimal to modest rates of vertical crustal movements. Located at Port MacDonnell, in Southern Australia, the sedimentary succession is represented by a flint conglomerate beach facies with interstratified shells. An optically stimulated luminescence (OSL) age of 53 ± 4 ka for an aeolianite unit that unconformably overlies the shelly deposit indicates that the beach facies is older than early MIS 3. OSL analysis also confirms that the MacDonnell Range, located 7 km inland from the present coastline, is of last interglacial age (124 ± 10 ka; MIS 5e). Radiocarbon dating on the operculum of Turbo undulatus from the shelly conglomerate yielded a minimum age of 47,905 ± 2106 yr BP [Wk-34733]. The extent of amino acid racemization (AAR) for Turbo sp. from the shelly unit beneath the aeolianite suggests an interstadial age (102 ± 16 ka). Uplift-corrected palaeo-sea level at the time of deposition of the shelly flint conglomerate was at least − 14 m during MIS 5c. These results are consistent with palaeo-sea level estimates from other far-field settings as well as oxygen isotope-inferred sea levels for this interval and further highlight the regional tectonic stability of Australian coastal landscapes in a global context.

Monitoring tectonic uplift and paleoenvironmental reconstruction for marine terraces near Maǧaracik and Samandaǧ, Hatay Province, Turkey.

Near Hatay, the Antakya-Samandağ-Cyprus Fault (ASCF), East Anatolian and Dead Sea Fault Zones, the large faults that form the edges of the African, Anatolian, Cyprus and Arabian Plates, all produce large earthquakes, which have decimated Hatay repeatedly. Near Samandağ, Hatay, differential vertical displacement on the ASCF has uplifted the southeastern side relative to northwestern side, producing large fault scarps that parallel the Asi (Orontes) River. Tectonic uplift coupled with Quaternary sealevel fluctuations has produced several stacked marine terraces stranded above current sealevel. This study dated 24 mollusc samples from 10 outcrops on six marine terraces near Samandağ electron spin resonance (ESR). Ages were calculated using time-averaged and volumetrically averaged external dose rates, modelled by assuming typical water depths for the individual species and sediment thicknesses estimated from geological criteria. Uplift rates were then calculated for each fault block. At all the Mağaracık terraces, the dates suggest that many shells were likely reworked. On the 30 m terrace at Mağaracık IV (UTM 766588-3999880), Lithophagus burrows with in situ shells cross the unconformity. One such shell dated to 62 ± 6 ka, setting the minimum possible age for the terrace. For all the Mağaracık terraces at ∼30 m above mean sealevel (amsl), the youngest ages for the reworked shells, which averaged 60 ± 3 ka for six separate analyses, sets the maximum possible age for this unit. Thus, the terrace must date to 60-62 ± 3 ka, at the MIS 3/4 boundary when temperatures and sealevels were fluctuating rapidly. Older units dating to MIS 7, 6, and 5 likely were being eroded to supply some fossils found in this terrace. At Mağaracık Dump (UTM 765391-4001048), ∼103 m amsl, Ostrea and other shells were found cemented in growth position to the limestone boulders outcropping there <2.0 m above a wave-eroded notch. If the oysters grew at the same time as the wave-cut notch and the related terrace, the date, 91 ± 13 ka, for the oysters, this fault block has been uplifted at 1.19 ± 0.15 m ky(-1), since MIS 5c. At Samandağ Kurt Stream at 38 m amsl, molluscs were deposited fine sandy gravel, which was likely formed in a large tidal channel. Four molluscs averaged 116 ± 5 ka. If these molluscs have not been reworked, this fault block has uplifted at 0.34 ± 0.05 m ky(-1) since the MIS 5d/5e boundary. The differences in these uplift rates suggests that at least one, and possibly two, hitherto undiscovered faults may separate the Mağaracık Dump site from the other Mağaracık sites and from the Samandağ Kurt Stream site.

Pedogenic and palaeoclimatic evidence from an Eemian calcrete in north‐western Sardinia (Italy)

A multidisciplinary approach was followed to study the pedogenic and palaeoclimatic information preserved in a buried palaeosol belonging to a Late Quaternary succession located along the bay of Alghero (north‐western Sardinia). The bay is dominated by a 5‐km long sandy beach‐ridge system backing an N‐S oriented lagoon system (Calich). The succession studied is characterized by basal shallow marine deposits, followed by clayey lagoon sediments and colluvial strata and capped by a relatively thick aeolianite. The research was based on pedological and sedimentological analyses, supported by optically stimulated luminescence (OSL) dating and by an in‐depth micro‐morphological study. Three main climatic pulses were highlighted during the Eemian. A wet period, with intense carbonate leaching occurred at the very beginning of the Eemian interglacial followed by very dry climatic conditions. This dry phase was long and arid enough to allow the formation of a thick calcrete hardpan, a typical feature of semi‐arid environments. The hardpan is dated at about 120 ka (kilo annum) and this dry event is tentatively associated with the late Eemian arid pulse (LEAP). The last phase of the Eemian recorded the restoration of a wetter climate. Finally, the succession indicated that even in a cooler environment, the central Mediterranean most probably maintained temperate conditions at least until the end of the MIS 5c (about 95 ka; early Würm).

Middle Pleistocene to Holocene coastal evolution of NW Sardinia (Mediterranean Sea, Italy)

The Middle Pleistocene–Holocene Sardinian stratigraphy has been revised to identify the roles played by sea and climate changes in controlling sedimentation. The succession, dated through Optically Stimulated Luminescence (quartz, K-feldspar) and 14C (the most recent) was grouped into eight major stratigraphic units mainly represented by coastal dunes, shallow marine, and alluvial systems. These units range in age from MIS 8 (300 ka) to MIS1 (6 ka).Little information is available for the period between MIS 8 and 6. The available data, however, allow some comments on climate changes over the last 125 ka. The last interglacial (MIS 5) is subdivided into five substages (e–a). MIS5e (Eemian) is considered the climate optimum of this interglacial, sea level was 4–6 m higher than today, and climate conditions were warmer and more humid. MIS 5c is the second high stand peak. Sea level was about 1.5 m above the modern level, and paleoclimatic and paleogeographic conditions were similar to the present. During MIS 4, at the beginning of the glacial phase, a climatic deterioration occurred. Temperatures dropped by 6C° relative to MIS 5e in about 5 ka, and sea level fell about 60 m. This led to a progressive disruption of inland vegetation cover and to repeated valley slope denudation. The sea-level fall created the accommodation space for fan development in sheltered and cliffed areas, where debris flows developed and filled almost completely the terminal parts of the narrow coastal valleys/coves. In wider areas, however, coastal dune fields developed. Contemporaneous presence of alluvial fan and dune systems is associated with the local morphology that could mitigate or amplify moist conditions within a generally arid environment.During MIS 3, several climate fluctuations occurred (wet/arid, D/O-H events). However, the shallow Sardinian shelf was continuously sufficiently exposed to become the source area of bioclastic sands. These sands were blown inland, and formed extensive dunefield systems. Dunes dominated the west coasts of Sardinia under cold and relatively dry conditions. In some areas, these dunefield systems were eventually almost completely dismantled and reworked into water-flow dominated alluvial fans by catastrophic rainfall events. Thus, the local climate quickly switched from arid to humid conditions. No record of the last Glacial Maximum deposits, MIS 2, was observed along the NW Sardinian coast. During the Holocene transgression (MIS1) coastal dune systems developed and progressively migrated inland, and temperature rose to reach the present-day condition.

A comparison of three Eurasian chironomid–climate calibration datasets on a W–E continentality gradient and the implications for quantitative temperature reconstructions

Multiple regional chironomid–climate calibration datasets are available to reconstruct quantitatively July air temperatures from fossil chironomid assemblages. We examined the relationship between July air temperature and the 40 most common chironomid taxa in three independent Eurasian calibration (training) sets. The estimated temperature optimum of each chironomid taxon is systematically lower (by ~1–2 °C) in a Norwegian calibration set compared to Finnish and Russian calibration sets. This result might partly be explained by the fact that the Norwegian calibration set extends further at the cold end of the temperature gradient. A difference in continentality between the Russian sites and the European sites might also contribute to this pattern. The number of taxa that show a statistically significant unimodal response to temperature is higher in the Norwegian calibration set (34 out of 40 taxa) compared to the modern Finnish (11 of 37 taxa; 3 common taxa absent) and the Russian calibration set (20 of 40 taxa), probably due to the longer temperature gradient incorporated in the Norwegian calibration set. We applied all three calibration sets to fossil chironomid assemblages from the high-latitude study site of Sokli (northeast Finland), a site with a unique series of lacustrine deposits covering (amongst others) the Holocene, part of early MIS 3 (at ~53 ka) and MIS 5d–c (at ~110–95 ka) and with independent proxy-records for comparison. In the early Holocene and during MIS 5c, the chironomid-based temperature inferences from all three inference models had similar values. Temperature reconstructions based on the Norwegian calibration set are 2–4 °C lower for the late Holocene, early MIS 3 and MIS 5d than the inferred temperatures based on the other calibration sets. Although the lakes included in the Finnish calibration set are located closest to the site of Sokli, evaluation tests and a comparison with independent proxy data suggests that the Norwegian calibration set provides the most suitable analogues for reconstruction purposes for most of the fossil assemblages. Our results imply that when choosing a calibration set for quantitative climate reconstructions on glacial timescales, regional proximity of the fossil site may not be a sufficient basis, and the length of the temperature gradient of the calibration dataset and factors such as the continentality gradient covered by the calibration set must also be considered.

Environmental interpretation of fossil insect assemblages from MIS 5 at Ziegler Reservoir, Snowmass Village, Colorado

Organic-rich lake sediments from a trench exposed at the Ziegler Reservoir fossil site near Snowmass Village, Colorado yielded a sequence of 27 insect fossil assemblages, spanning the time interval from about 125 to 77ka. The assemblages appear to represent MIS 5e, 5c, 5b, and 5a. A total of 99 taxa were identified, mostly beetles. The fossils represent the oldest known Pleistocene insect faunas from high elevation in the Rocky Mountains, and document a series of climatic oscillations from full interglacial to stadial and interstadial environments, accompanied by changes in regional biological communities. The MIS 5e fauna indicates summer temperatures similar to modern values, with winter temperatures 5–7°C cooler than today. Regional climates cooled somewhat by MIS 5c, and during MIS 5b summer temperatures were 5–6°C colder than modern values. Summer temperatures recovered to near-modern levels during early MIS 5a, and cooled by 1–2°C at its end, although winter temperatures were apparently above modern levels. The indication of milder but wetter winters, strengthened by the inclusion of species found today only in the Pacific Northwest region, suggests conditions that may have led to increased snowpack at high elevations in this part of the Rocky Mountains, linked with the onset of MIS 4 glaciation.

Archaeological sites of the Süttő Travertine Complex (Hungary) with stratigraphical and paleoecological implications from their faunas

The Süttő Travertine Complex in northern Hungary is known in the geological literature for more than a century as a series of paleontological sites. This site is one of the largest travertine occurrences of the Gerecse Hills. Loose Upper Pleistocene eolian sediments (mainly Riss-Würmian loess and Holocene topsoil) cover the eroded surface of the travertine. Beside vertebrate assemblages, two archaeological sites were described from this area. One (Süttő-Diósárok) was a Paleolithic fire pit situated in the road cut between Süttő and the quarries, while the other one was discovered in a fissure of the northern wall of Diósvölgy Quarry. The latter is part of the Süttő 1 vertebrate site.Vértes (1965) referred the artifacts from Süttő-Diósárok to the Moustérian (Tata Culture). This site is referred here to MIS 5c, based on the vertebrate and snail faunas representing warm and dry climate, and steppe-like vegetation, as well as the tool-bearing dark brown chernozem-like paleosol layer of the loess–paleosol sequence, with a luminescence age of 93.7 ± 21.1 ka.Artificially fractured bones were excavated from the small cavity of Süttő 1. Some of those remains display toolmarks. Unfortunately, these bones are currently missing from the collection. The latter artifacts most likely belong to a level which pre-dates the Tata Culture. Paleoecological inferences based on the mammalian and mollusc faunas indicated warm, humid climate and forest vegetation, therefore suggesting a stratigraphic correlation of Süttő 1 with the Eemian interglacial (MIS 5e).

Late Pleistocene climate change and landscape dynamics in the Eastern Alps: the inner-alpine Unterangerberg record (Austria)

Drill cores from the inner-alpine valley terrace of Unterangerberg, located in the Eastern Alps of Austria, offer first insights into a Pleistocene sedimentary record that was not accessible so far. The succession comprises diamict, gravel, sand, lignite and thick, fine grained sediments. Additionally, cataclastic deposits originating from two paleo-landslide events are present. Multi-proxy analyses including sedimentological and palynological investigations as well as radiocarbon and luminescence data record the onset of the last glacial period (Würmian) at Unterangerberg at ∼120–110 ka. This first time period, correlated to the MIS 5d, was characterised by strong fluvial aggradation under cold climatic conditions, with only sparse vegetation cover. Furthermore, two large and quasi-synchronous landslide events occurred during this time interval. No record of the first Early Würmian interstadial (MIS 5c) is preserved. During the second Early Würmian interstadial (MIS 5a), the local vegetation was characterised by a boreal forest dominated by Picea, with few thermophilous elements. The subsequent collapse of the vegetation is recorded by sediments dated to ∼70–60 ka (i.e. MIS 4), with very low pollen concentrations and the potential presence of permafrost. Climatic conditions improved again between ∼55 and 45 ka (MIS 3) and cold-adapted trees re-appeared during interstadials, forming an open forest vegetation. MIS 3 stadials were shorter and less severe than the MIS 4 at Unterangerberg, and vegetation during these cold phases was mainly composed of shrubs, herbs and grasses, similar to what is known from today's alpine timberline. The Unterangerberg record ended at ∼45 ka and/or was truncated by ice during the Last Glacial Maximum.

Pleistocene vertebrate faunas of the Süttő Travertine Complex (Hungary)

Numerous fossil remains (vertebrates, molluscs and plants) were found in more than twenty sites of the Süttő Travertine Complex during the last 150 years. The majority of these remains were recovered from fissures of the travertine, but also from the travertine and an overlying loess–paleosol sequence. The aims of this study were to review the fossil content, to determine the stratigraphical positions of the various vertebrate faunas of Süttő and provide paleoecological interpretation of the periods on the basis of their faunas and floras. In addition, this paper describes new faunas and floras from the sites Süttő 16–20 and provides 14C dates for Süttő 16.On the basis of the new uranium series isotope and optical dating (OSL), the age of the travertine complex is Middle Pleistocene (235 ± 21–314 ± 45 ka, MIS 7–9), while the age of the loess–paleosol sequence in superposition of the travertine is Middle–Late Pleistocene (MIS 2–MIS 6). In contrast, the fossils of the travertine indicated an older, Pliocene–Early Pleistocene age. A fissure (Süttő 17) and a red clay layer (Süttő 19) contained mammal faunas of Early–Middle Pleistocene age. These results indicated the existence of older travertine in certain quarries (Hegyháti quarry, Cukor quarry).Sedimentological and OSL data of well-dated layers of the loess–paleosol sequence (Süttő/LPS) at Süttő allowed a correlation with the layers of Süttő 6. The paleosol layer in the upper part of the sequence of Süttő 6, was correlated with a pedocomplex of the overlying loess–paleosol sequence, which was dated to MIS 5c (upper, dark soil) and MIS 5e (lower, reddish brown soil). The paleoecological analysis of the mammal and mollusc faunas supported the former interpretation of Novothny et al. (2011) inferring warm, dry climate during the sedimentation of the upper layers, and more humid climate for the lower layers). However, the fauna of the lower soil layer indicated cold climate, so an age of MIS 5d is suggested.Dating of the fissure faunas is based on similarity studies. For some faunas, this method cannot be used, because of the low number of species. On the basis of the species compositions and former interpretations, these faunas originated mainly from sediments that were deposited under cold climatic conditions. Other fissure faunas were dated by AMS 14C (Süttő 16), or by correlation with soil layers of Süttő 6. According to these results, most of the fissure faunas can be correlated with different phases of MIS 5. However, there are a younger (MIS 2) and an older (Early–Middle Pleistocene) fissure fauna also.

A short-term climate oscillation during the Holsteinian interglacial (MIS 11c): Characteristics, spatial extent and potential triggering mechanisms

A short-term climate oscillation during the Holsteinian interglacial (MIS 11c): Characteristics, spatial extent and potential triggering mechanisms

Coupled U-series and OSL dating of a Late Pleistocene cave sediment sequence, Morocco, North Africa: Significance for constructing Palaeolithic chronologies

Cave sequences provide some of the most important archives of Palaeolithic archaeology that are currently available. The potential value of such sequences is, however, frequently limited by the problems associated with constructing robust chronologies for archaeologically significant levels. In this study, we apply 230Th/U and OSL SAR techniques to the dating of deposits from the Calcareous Group at Grotte des Pigeons, Taforalt, eastern Morocco. The advantage of combining these techniques is: 1) they allow the cross-checking of chronologies derived from independent sets of measurements and assumptions, and 2) they date different facies of cave sediments (i.e. clastic cave sediments as opposed to cave precipitates such as speleothems) allowing the timing of deposition by different cave processes to be constrained more robustly. The age estimates derived by these techniques from different sampling locations are in good agreement with one another, suggesting the potential of these techniques when used in tandem for producing more robust chronologies of Palaeolithic sequences. The deposition of the Calcareous Group is placed within the middle to late part of MIS 5 (MIS 5c to 5a). Furthermore, the Bayesian analysis of the dates derived in this study along with those that have been previously published, allows the duration of deposition of this unit to be estimated at 25.4 ± 3.7 ka (mean ± 1σ). The paper concludes by discussing the significance of these ages for the archaeology of the Taforalt sequence. We suggest that the collection of samples for multiple independent dating methods in direct association combined with the use of careful, stratigraphic constraints in Bayesian models results in the most robust dates available for such cave sequences.

A short-term climate oscillation during the Holsteinian interglacial (MIS 11c): An analogy to the 8.2 ka climatic event?

To gain insights into the mechanisms of abrupt climate change within interglacials, we have examined the characteristics and spatial extent of a prominent, climatically induced vegetation setback during the Holsteinian interglacial (Marine Isotope Stage 11c). Based on analyses of pollen and varves of lake sediments from Dethlingen (northern Germany), this climatic oscillation, here termed the “Older Holsteinian Oscillation” (OHO), lasted 220years. It can be subdivided into a 90-year-long decline of temperate tree taxa associated with an expansion of Pinus and herbs, and a 130-year-long recovery phase marked by the expansion of Betula and Alnus, and the subsequent recovery of temperate trees. The climate-induced nature of the OHO is corroborated by changes in diatom assemblages and δ18O measured on biogenic silica indicating an impact on the aquatic ecosystem of the Dethlingen paleolake. The OHO is widely documented in pollen records from Europe north of 50° latitude and is characterized by boreal climate conditions with cold winters from the British Isles to Poland, with a gradient of decreasing temperature and moisture availability, and increased continentality towards eastern Europe. This pattern points to a weakened influence of the westerlies and/or a stronger influence of the Siberian High. A comparison of the OHO with the 8.2ka event of the Holocene reveals close similarities regarding the imprint on terrestrial ecosystems and the interglacial boundary conditions. Hence, in analogy to the 8.2ka event, a transient, meltwater-induced slowdown of the North Atlantic Deep Water formation appears as a plausible trigger mechanism for the OHO. If correct, meltwater release into the North Atlantic may be a more common agent of abrupt climate change during interglacials than previously thought. We conclude that meltwater-induced climate setbacks during interglacials preferentially occurred when low rates of summer insolation increase during the preceding terminations facilitated the persistence of large-scale continental ice-sheets well into the interglacials.

Vegetation patterns under climate changes in the Eemian and Early Weichselian in Central Europe inferred from a palynological sequence from Ustków (central Poland)

This paper presents a fresh examination of a pollen profile from Ustków (central Poland), which after preliminary results was thought to span a period between the Early Eemian (MIS 5e) and the upper Pleni-Weichselian (MIS 3). The newly obtained results confirmed the age assessment of the bottom series, but revealed a much older age for the uppermost part of the profile as far back as the Rederstall stadial (MIS 5b). Palynological research showed slightly different patterns of vegetation in comparison to other sites located in Central Europe. Among them were an early Ulmus maximum coinciding with the Betula optimum in the Early Eemian, a relatively late optimum of Taxus baccata during the decline of the Middle Eemian, and a distinct division of the older part of the Late Eemian into phases of Abies-Picea and Picea-Pinus forest domination. The Herning stadial (MIS 5d) falls into a typical bipartition reflected by heathland domination during its older part and the prevalence of Juniperus thickets and Artemisia-Poaceae steppe during its younger part, which makes this succession similar to those from northern Germany. The pollen spectra reflecting the Brørup interstadial (MIS 5c) distinctly revealed an intra-Brørup cold oscillation rarely detected in profiles from Central Europe and a period of Larix dominated forests during the latest part of the interstadial (extraordinarily high percentages exceeding 15% of the total pollen sum). Local pollen taxa, together with the lithological composition of deposits, revealed that there was a water body in the area during the periods of the Late Saalian/Early Eemian transition–Middle Eemian (the decline of the Tilia phase), the Herning stadial (MIS 5d), the early Brørup interstadial (MIS 5c), and the Rederstall stadial (MIS 5b). Between these time-intervals a poor and/or rich fen and/or bog functioned.

Large shifts in vegetation and climate during the Early Weichselian (MIS 5d-c) inferred from multi-proxy evidence at Sokli (northern Finland)

For decades, detailed studies on Early Weichselian deposits have been made in central Europe. In contrast, these studies are rare in Fennoscandia in northern Europe. We here integrate an extensive multi-proxy data set obtained on sediments of MIS 5d-c age that form part of a long sediment record preserved at Sokli in northern Finland. We make a detailed interpretation of the vegetation and depositional history for MIS 5d-c using pollen, macrofossils, diatoms and other siliceous microfossils, insect remains, and sediment characteristics, and combine these data with recently published estimates on July temperatures based on chironomids and selected plant indicator species in order to make inferences of paleo-climate regimes. The fossil record obtained on the seven meter thick MIS 5d-c deposit at Sokli is exceptionally rich in species due to the large variety of habitats associated with an overall fluvial depositional environment. A braided river system flanked by steppe-tundra vegetation is inferred for MIS 5d. Mean July temperatures of at least 12–14 °C are indicated by chironomids and plant indicator species and are in agreement with the presence of conifers and birch trees as recorded by macrofossils. The reconstructed environmental conditions suggest strong continental climate conditions at Sokli during MIS 5d. The gradual infilling of an oxbow lake and subsequent return to stream channel deposition is traced in great detail in the overlying gyttja and gravelly sediment of MIS 5c age. The terrestrial pollen and plant macrofossil record from the gyttja shows the establishment of birch forest followed by the spread of pine and then spruce. Rich plant indicator species assemblages indicate that the boreal environment at Sokli during MIS 5c experienced July temperatures several degrees higher than the present-day value of 13 °C. The high summer temperatures and presence of larch suggest more continental conditions. More open vegetation returned at Sokli during late MIS 5c and was followed by glaciation by the Fennoscandian Ice Sheet (MIS 5b). Despite the major differences in zonal vegetation types during MIS 5d-c, differences in reconstructed July temperatures are minor and suggest that winter temperatures combined with precipitation values mostly determined the stadial–interstadial climate variability. The most compelling conclusion from our study is that forest development during MIS 5c was remarkably similar to that recorded for the Eemian (MIS 5e) and Holocene Interglacials at the high-latitude site Sokli, and also to that inferred from MIS 5c sediments on the northern European mainland. Our results question the definition of MIS 5c in the terrestrial record of Europe as an interstadial interval of the last glacial cycle and suggest inclusion of MIS 5c together with the Eemian (MIS 5e) in an interglacial complex.

The variegated (VT) tephra: A new regional marker for middle to late marine isotope stage 5 across Yukon and Alaska

The Variegated (VT) tephra, likely sourced from the eastern Aleutian arc, has a geographic distribution that places it amongst the most widespread tephra beds in eastern Beringia. First identified in the Fairbanks area of interior Alaska, it has been identified at eight additional sites ranging from Togiak Bay in southwestern Alaska, to the Klondike area of west-central Yukon. Correlation of these occurrences is established through the equivalence of glass major and trace-element geochemistry, Fe-Ti oxide geochemistry, stratigraphy, and independent age data. In Yukon and Alaska, VT tephra has a minimum bulk tephra volume estimate of ∼32 km 3. Previous age estimates for VT tephra have varied, ranging from a glass fission-track age of 125 ± 30 ka to a weighted mean thermoluminescence (TL) age of 77.8 ± 4.1 ka from bracketing ages on loess. A new infrared stimulated luminescence (IRSL) age of 106 ± 10 ka, paleoenvironmental data, and several TL and IRSL ages from Togiak Bay suggest that the time of deposition is more likely between these previous age estimates: post-marine isotope stage (MIS) 5e but underlying a prominent soil likely associated with MIS 5c, placing it within late MIS 5d.

“Warm” stages in the West Siberian Late Pleistocene

The revised study of stratotypes and key sections of the Karginsky regiostage in the West Siberian Plain with the use of 230Th/U dating determinations and advanced 14C dating indicated that many 14C ages obtained in the 1960–1970s were incorrect, and revealed the pre-Karginsky age of the Karginsky regional substage stratotypes adopted in the modern Pleistocene stratigraphic schemes of West Siberia. The available 230Th/U and 14C data along with the new paleobotanical record provided substantial refinement of the Late Pleistocene succession of paleoclimatic events in the West Siberian Plain. The 5e5 and 5e1 optima corresponding to climatic events of the Greenland ice core and 5e2 and 5e4 pessima are revealed in boreal West Siberia. The obtained 230Th/U dating determinations, even with their wide tolerance interval, make it possible to recognize not only the major but certain minor climatic events within the Kazantsevsky interglacial in boreal West Siberia. Beds corresponding to MIS 5c are recorded in the middle reaches of the Ob River. The preceding cooling was comparable with that of the later stages of the Zyryansky glaciation and is correlated with MIS 5d, which suggests the beginning of the Zyryansky glaciation occurred in the second half of MIS 5. The obtained records do not require elimination or reducing of the range of the Karginsky regiostage. However, the stratotypes of its regional sub-stages, chosen mainly in the 1960–1970s, appear to be invalid.

Geoarchaeological alluvial terrace system in Tarazona: Chronostratigraphical transition of Mode 2 to Mode 3 during the middle-upper pleistocene in the Guadalquivir River valley (Seville, Spain)

A geoarchaeological study of some lithic assemblages found in late Middle Pleistocene and beginning Upper Pleistocene alluvial terraces system has been carried out. The MIS 6/MIS 5 transition in the fluvial terraces of the Guadalquivir River has been identified in the Middle Terraces Complex (MTC) at Tarazona (T11.1, +44–38 m and T11.2, +36–30 m) Seville (Spain). The results were obtained from an archaeological excavation (TAR-III), and two other complementary archaeological sites (TAR-I and TAR-II). Geomorphological cartography, chronostratigraphic study with OSL dating, cantometric analysis and technotypological characterization of 5870 lithic pieces (measurement techniques for erosion and transport on gravels and lithic) have been accomplished. The alluvial chronosequence shows a probable climatic character with autocyclic sedimentary processes correlated with the transition from MIS 6 to MIS 5. Four alluvial Episodes with associated lithic techno-complexes were identified, which refer to the chronostratigraphic transition from Mode 2 to Mode 3 during the late Middle Pleistocene (MIS 6) and the beginning of Upper Pleistocene (MIS 5): Episode 1 with Mode 2 (MIS 6); Episode 2 with varied assemblages that could be associated to Mode 2 or Mode 3 (129/121 ka, MIS 5e and MIS 5d, pre-110 ka); Episode 3 with Mode 3 (between 110 and 104 ka, MIS 5c), and Episode 4 with Mode 3 (post-MIS 5c). The archaeological sites have lithic pieces which were knapped in situ (workshop, habitual or temporary sites) or were slightly displaced. The raw material selection of high quality (quartzites from alluvial deposits) is very notable during Mode 2 (Acheulian) (TAR-I2), Mode 2 or Mode 3 assemblages (TAR-III5) and Mode 3 (TAR-III1, 2, 3). During Mode 3 (Middle Paleolithic) (TAR-II1), the selection of flint raw material was from areas near or in the Guadalquivir terraces.

A high-resolution Late Quaternary climatostratigraphic record from Iskitim, Priobie Loess Plateau, SW Siberia

The Siberian loess, being a part of the Eurasian loess belt, has provided the most complete terrestrial record of past climate change in the north-central Asia. The continuous high-resolution sections of aeolian dust deposits inter-bedded with fossil soils from the Priobie Loess Plateau and the Northern Altai Plains – mapped as a part of the 2000 km W–E Siberian palaeoclimate transect – have produced extraordinary evidence of the Late Quaternary climate evolution and landscape development in the parkland-steppe north of the Altai-Sayan Mountains. A complete stratigraphic loess-palaeosol record was studied at the Iskitim reference section, spanning the last c. 250 ka (MIS 7-1). The climate-indicative proxy data (magnetic susceptibility, grain size, %CaCO 3, %TOC) and thin-section studies show marked and cyclic climatic variations, particularly pronounced during the Last Interglacial–Glacial cycle equivalent to the loess reference sites from the Yenisei and Katun/Altai Plain areas (the Kurtak and Krasnogorskoye sections). The Iskitim loess-palaeosol record illustrates a rapid onset of the Last Interglacial in agreement with the marine oxygen isotope records, with a strongly continental warm climate culminating around the peak of the Last Interglacial (MIS 5e). This was succeeded by a dramatic cooling (MIS 5d) defined by a major cryogenic event that resulted in deformation of the MIS 5e chernozem followed by loess deposition in congruence with the Lake Baikal detrital stratigraphic sequence. Cooler climate conditions during the subsequent interglacial sub-stages (MIS 5c and 5a) correspond to shifts in the bioclimatic zonal development, with a gradual replacement of parkland-steppe and mixed southern taiga by boreal forest, and by cold arid periglacial tundra-steppe during the stadial sub-stages (MIS 5d and 5b). Following the most intensive loess sedimentation during the early Last Glacial (MIS 4), a new cycle with warm and very cold climate variations characterises the mid-Last Glacial interstadial interval (MIS 3), with most favourable surface-stabilisation phases represented by cryogenically distorted parkland chernozem soils. The Iskitim loess-palaeosol sequence, characterised by intensive syndepositional pedogenic processes, provides unique evidence of a dynamic climate change during the Late Quaternary in the continental north-central Asia and a linkage site for transcontinental Eurasian correlations of high-resolution loess records.