Late Pleistocene Deposits Research Articles

Chloritoid in the bottom sediments of the Akademichesky Ridge of Lake Baikal, an indicator of eolian transportation

We present results of study of Holocene and Late Pleistocene deposits recovered on the underwater Akademichesky Ridge in Lake Baikal. The change in mineral composition and grain size in the bottom sediment core is closely consistent with the change of major diatom complexes marking the Holocene–Late Pleistocene boundary. A high content of chloritoid (up to 14.6%) has been found among the heavy minerals of the sand fraction of Late Pleistocene clays. The concentration of chloritoid in Holocene mud is no higher than 1.2%. The source of chloritoid is chloritoid shales of the Anaya Formation (Upper Proterozoic), widespread in the watershed of the Primorsky Ridge in the upper reaches of the Lena and Anaya Rivers. Chloritoid was transported to the area of the Akademichesky Ridge by predominant western and northwestern winds, which is also evidenced from the absence of mechanical impacts on the surface of its grains. The high contents of chloritoid in the Late Pleistocene sediments are due to the more intense eolian transportation at that time as compared with the Holocene.

Eolian and fluvial sedimentation in the southwestern Sinai Mountains, Egypt: a record of flash floods during the late Pleistocene

Wadis emerging from the southwestern Sinai Mountains (Egypt) westwards to the Gulf of Suez are filled by >40 m thick late Pleistocene sediments, which have been subsequently incised to bedrock after the Last Glacial Maximum (LGM). Sedimentation and erosion resulted from changes in the basin's hydrological conditions caused by climate variations. Sediment characteristics indicate distinct processes ranging from high to low energy flow regimes. Airborne material is important as a sediment source. The fills are associated with alluvial fans at wadi mouths at the mountain fronts. Each alluvial fan is associated and physically correlated with the respective sediment fill in its contributing wadi. The alluvial fans have steep gradients and are only a few kilometers long or wide. The alluvial fans converge as they emerge from the adjacent valleys. According to optically stimulated luminescence dating, the initial sediment has an age of ∼45 ka and the sedimentation ends ∼19 ka, i.e., happened mainly during marine isotope stage (MIS) 3 and early MIS 2 formation and initial incision sometime during LGM. As the delivery of sediments in such a hyper-arid environment is by extreme floods, this study indicates an interval of intense fluvial activity, probably related to increased frequency of extreme floods in Southern Sinai. This potentially indicates a paleoclimatic change in this hyper-arid environment.

Late Pleistocene Lizards from Fowlkes Cave, Culberson County, Texas

Abstract Fossils of five or more genera and six species of lizards were identified from late Pleistocene sediments of Fowlkes Cave, Culberson County, Texas. The most abundant species was the roundtail horned lizard Phrynosoma modestum (45 individuals), a common lizard in the Recent Chihuahuan Desert, but the greatest number of fossils represented ≥83 individuals of Phrynosomatidae genus and species indeterminate. Fossils identified to at least the generic level appear to represent xeric-adapted lizards that occur in habitats typical of the Chihuahuan Desert that occur around the cave today.

The depositional Environment at Shuidonggou Locality 2 in Northwest China at ∼72–18 kaBP

Abstract:Shuidonggou site has abundant Paleolithic remains of Late Pleistocene deposition. Studying the evolution of depositional environments is essential to the comprehensive understanding of the living conditions of ancient populations. To reconstruct the depositional environment at Shuidonggou, we carried out archaeological excavations and collected systematic deposition samples at the key position of Shuidonggou Locality 2 for grain size analysis and sporopollen statistics. The environmental evolution around the Shuidonggou site generally underwent four stages at ∼72–18 kaBP. During the first stage (∼72–41 kaBP), the river developed with gravel and sand stratums. During the second stage (41∼34 kaBP), a swamp with numerous aquatic plants formed. In the third stage (34–29 kaBP), site formation was characterized by shallow lake depositional conditions; the climate was relatively warm and humid. The marginal bank depositional conditions deteriorated during the fourth stage (29–18 kaBP), and the site underwent several dry events; the climate also became drier and colder.

On the occurrence of the scimitar-toothed cat, Homotherium latidens (Carnivora; Felidae), at Kents Cavern, England

Teeth of Homotherium latidens recovered from late Pleistocene sediments, Kents Cavern, England have long been the source of controversy. H. latidens is conspicuously absent from other late Pleistocene cave deposits in Britain, and is widely thought to have been extirpated from the region during the isotope stage 10 glacial period. Here we present high spatial resolution analyses of fluorine and uranium uptake profiles in teeth of three species from the same cave. The H. latidens tooth is clearly distinguished from the unambiguously provenanced Late Pleistocene hyaena and Middle Pleistocene cave bear teeth. These results are consistent with the theory that the H. latidens teeth originated at an exogenous location, were probably transported to Kents Cavern as Palaeolithic trade goods, and were buried in Kents Cavern in Palaeolithic times.

43. Global warming and expanding the range of feral conditions in Yakutia – The coldest region of the North-East Asia

In Yakutia, there has long been a number of natural foci of infectious human and animal diseases such as tularemia, anthrax, rabies, brucellosis, leptospirosis and others. The circulation of pathogens in nature is closely connected with the peculiarities of natural ecosystems and their animal populations, especially the mass species of birds and mammals and their ecto-and endoparasites. Global warming has caused the expansion to the north of the range of many species of birds and their ectoparasites from the southern parts of the Asia–Pacific region. There was the possibility of the spread causative agent of avian influenza H5N1 dangerous to humans, in-line with those observed in recent decades, global warming and the expansion of the range of animal-carriers and custodians of infectious agents are expanding the range of feral diseases such as rabies, brucellosis,and encephalitis, stable foci of new diseases, including pseudotuberculosis, have appeared in our region. With further advancement of the classical forms of rabies in South Yakutia in the central and northern areas of the Arctic, the counter-propagation form of rabies may occur to the south, with the genetic restructuring of their agents as a result of recombination of genes and new mutations. Melting of permafrost soils and an irrigation of territories can promote “awakening” of the centres, previously widespread in the region, of a malignant anthrax and natural smallpox. There is concern has about the recently established detection of viable, including spore-forming, micro-organisms in the remains of the mammoth fauna of the natural burial sites in the Late Pleistocene permafrost sediments over time. The latter indicates that there is potential for the release of pathogens from the surface of especially dangerous infections from that era (epidemiological echo). Previously, Somov (1974), who worked many years in Chukotka and other regions of the Russian Far East, put forward a hypothesis on the preservation of psychrophilic pathogens infections at low temperatures of the environment in saprophytic state that only if it enters the human body become virulent. In this regard, we suggested in 1980 that “the further development of the northern territories may appear natural foci of new, perhaps previously unknown infectious diseases”. Thus, global warming contributes to increased incidence of especially dangerous infections by expanding the range of animal carriers and disseminators of infection due to possible preservation at low temperatures in the state of saprophytic pathogens in the active state.

Deep gullies entrenchment in valley fills during the Late Holocene in the Basento basin, Basilicata (southern Italy)

Deeply entrenched channels namely badland gullies occur on the gently sloping valley floors of any alluvial basins in the semi-arid environments of Fossa Bradanica, Basilicata, southern Italy. Valley fills in this region consist of predominantly Holocene alluvium; late Pleistocene deposits occur as terraces above the present flood plain or as eroded benches buried beneath younger alluvium. Historical fluvial deposition began before 7000 a cal. BP and ended at around 120 a cal. BP. In this study, we focus on the channel entrenchment (badland gullies incision) in the last 4500 years, based on a detailed study of chronostratigraphic alluvial sequences of Basento River. Four main phases of incision have been recorded at around 4500-4350, 1500, 900-800, and 120 a cal. BP. The formation of late-Holocene badland gullies can be related to changes in climate, vegetation and groundwater conditions. Environmental history mainly derived from the high-resolution pollen record of Lago Grande di Monticchio. Badland gullies formation appears to be linked to repeated dry-wet cycles. During dry periods, water tables significantly dropped and vegetation cover decreased with increase in runoff and water discharge from rainfall, leading to deepening and widening of stream channels.

Late Pleistocene sedimentation in the foreland of South-Eastern Alps

Late Pleistocene sedimentation in the foreland of South-Eastern Alps

Dating Late and Middle Pleistocene sediments using post infrared-infrared stimulated luminescence (post IR-IRSL) in K-feldspar

Dating Late and Middle Pleistocene sediments using post infrared-infrared stimulated luminescence (post IR-IRSL) in K-feldspar

Luminescence dating indicates radiocarbon age underestimation in late Pleistocene fluvial deposits from eastern England

Robust geochronological control is crucial for interpreting and correlating the environmental record from fragmentary terrestrial sequences from the last glacial period. Traditional terrestrial stratigraphies are typically reliant on radiocarbon dating, although estimates of antiquity for samples older than 40 ka may be unreliable. Optically stimulated luminescence (OSL) dating of sediments is an alternative for dating the whole of the last glacial period and also provides the opportunity to independently test radiocarbon based chronologies. This paper presents a set of nine directly comparable paired OSL and accelerator mass spectrometry (AMS) radiocarbon ages from multiple sites within Devensian fluvial sediments in lowland Britain and shows that it is possible to obtain robust OSL age estimates throughout this time period. The two techniques agree well for ages younger than ca. 29 14C ka BP (ca. 35 cal. ka BP) but disagree beyond ca. 35 14C ka BP (ca. 40 cal. ka BP). This is thought to be due to radiocarbon ages on older organic material having been contaminated by low levels of modern carbon. It is therefore suggested that all conventionally pre-treated radiocarbon ages greater than 35 14C ka BP should be treated with extreme caution.

Photons and fauna: OSL dating of late Pleistocene megafaunal deposits in south-western Western Australia

Photons and fauna: OSL dating of late Pleistocene megafaunal deposits in south-western Western Australia

Late Pleistocene beach deposits, tectonics and sea-level changes on Cyprus, and their possible association with Neolithic colonization and settlements

Late Pleistocene beach deposits, tectonics and sea-level changes on Cyprus, and their possible association with Neolithic colonization and settlements

Uranium comminution ages: Sediment transport and deposition time scales

The uranium isotope comminution age is determined from the 234U/238U ratio and reflects the timescale associated with the transformation of bedrock to sediment. The comminution age is applicable to Late Pleistocene sediments and measures the amount of time elapsed since sediment generation by mechanical weathering and erosion. The age significance of the 234U/238U ratios is based on physical disruption of the 238U-decay series by recoil loss of 234Th that occurs in mineral grains smaller than 50μm. Results from study of fine-grained deep sea sediments in the North Atlantic Ocean, alluvial sediments in California and Australia, and modern glacial outwash are encouraging, but critical aspects of the method require further investigation. Particular issues are the effects of laboratory chemical leaching treatment on sediment samples and estimation of 234U loss rates as a function of grain size. In the North Atlantic marine environment the U isotope variations are inferred to reflect differences in the transport time of the sediment–the time elapsed between the generation of the small sediment particles by glacial action in Iceland and Fennoscandian source areas, and the time of deposition on the seafloor in the North Atlantic Ocean at a drift site south of Iceland. Calculated transport times vary from less than 10kyr to about 400kyr, and correlate with provenance and glacial cycles. Application to alluvial sediments in California and Australia suggests that where sediments are glacially-derived and transported short distances, the U comminution age may approximate the sedimentation age, but in larger basins that are not glaciated the sediments retain information about residence/transport times that can extend to ca. 400kyr. To verify that initial 234U/238U ratios for glacial sediments are close to the secular equilibrium ratio, outwash from several major glaciers around the world was measured and found to be within±1% of the accepted equilibrium 234U/238U value.

Neotectonics and paleoseismicity of the lower Katun’ valley (Gorny Altai)

The lower Katun’ area has a complex neotectonic framework, with the largest fault zone of Katun’ consisting of several en-echelon graben segments. Late Pleistocene sediments that fill the Katun’ Fault bear signature of earthquake-induced soft-sediment deformation (seismites). Deformation due to seismic triggers can be discriminated from nonseismic one on the basis of special features and be related to prehistoric earthquakes according to a number of criteria. The observed deformation inside and outside burial mounds of the Chultukov Log-1 group may result from an earthquake that occurred in the end of the first millennium BC. Fault scarps in Late Pleistocene sediments, as well as deformed Iron Age tomb patterns, indicate that the Katun’ lower reaches can have experienced past earthquakes of intensity at least 5 or 6 and magnitudes from 4.5 to 6.0.

Late glacial and Holocene sedimentary environments of Quesnel Lake, British Columbia

At 512m Quesnel Lake is the third deepest in North America and at 100km long its drainage basin spans from the arid interior plateau to the high mountains of the eastern Cordillera where small glaciers are a significant source of sediment. In most of the lake sediment is 0 to 40m thick, reaching a maximum of just over 100m thick near the junction of the three arms. Cores from three locations in the lake provide evidence that the entire Holocene record is contained in the upper 4 to 6m of the sedimentary record where rates of accumulation have been constant or have decreased slowly. The highest rates (0.35 to 0.72mm/a) occur near points of inflow, while the lowest rate (0.22mm/a) occurs in a sheltered environment with limited inflow, and significant hypolimnic circulation which may flush water and suspended sediment from the water column. Late Pleistocene sediment beneath has a similar acoustic signature to the cored Holocene record above, suggesting that the sedimentary processes governing its deposition were not greatly different than in the present lake but that extensive glacial and paraglacial sources contributed to a significantly higher rate of accumulation. Mazama ash analyzed from two locations near points of inflow has an age of 7576±60cal. BP according to our chronology. Vivianite, which is uncommon in lakes of the Cordillera, occurs in the middle of the cores mainly associated with macroscopic wood fragments and indicates reducing conditions within the sediment.

Magnetic properties of greigite in the Late Pleistocene sediments of the North Caspian

The results of magnetic and X-ray studies of the magnetic extracts separated from highly magnetically susceptible horizons of the Late Pleistocene sediments from the North Caspian Basin are presented. Greigite is shown to be the major carrier of magnetic properties in these horizons. Its coercive parameters are characteristic of the predominantly single-domain state of magnetic grains. It is found that the Curie point of greigite is at least 460°C, while the specific magnetization of pure greigite is half the saturation magnetization of magnetite.

Delineating stratigraphic breaks at the bases of postglacial eolian dunes in central Alberta, Canada using a portable OSL reader

ABSTRACTTemporal constraints for the Late Pleistocene deposition of eolian dunes that occur in central and northern Alberta, Canada can be provided by dating sediments from the dune bases using luminescence techniques. In places, however, the postglacial dunes overlie glaciofluvial sands that resemble the eolian deposits in texture such that demarcating the bases of the dunes is often problematic. In this study we address the problem by employing a portable optically stimulated luminescence (OSL) reader to construct luminescence profiles that depict luminescence signal variation with depth. With the portable OSL reader, measurement can be performed on bulk sediments, negating the need for laborious separation procedures to isolate pure mineral fractions, as is required in regular luminescence dating. Measurements can also be carried out in the field, permitting quicker decision making during sample collection. Results from this study, presented as depth variations of feldspar derived infrared stimulated luminescence (IRSL) signals and predominantly quartz‐generated post‐IR blue OSL signals, show that luminescence profiling enables one to distinguish between eolian deposits that make up the dunes from the underlying non‐eolian sands. The identification of such cryptostratigraphic interfaces is made possible by differences in the dosimetric histories of the sediments. The delineation of the dune bases allows targeted sampling that yields best luminescence age approximations for the initiation of postglacial eolian deposition in the region. Luminescence profiling of eolian sequences would also, in theory, permit the identification of depositional breaks of extended duration. Copyright © 2012 John Wiley & Sons, Ltd.

Origin of magnetic mineral concentration variation in the Southern Ocean

In the Southern Ocean, magnetic mineral concentration increases in glacial periods. The variation pattern closely resembles eolian dust flux records from Antarctic ice cores, but the cause of the linkage remains unclear, as the dust flux is too small for the source of terrigenous materials in the Southern Ocean. We have conducted an environmental magnetic study of late Pleistocene sediments from the south Indian Ocean to investigate the origin of the magnetic concentration changes. Biogenic magnetites can be detected using the characteristics of almost no magnetostatic interactions and narrow coercivity distribution, reflecting occurrence of single‐domain magnetites in a chain. We interpret that a non‐interacting component on first‐order reversal curve diagrams and low‐coercivity components with small dispersion from isothermal remanent magnetization (IRM) component analyses represent biogenic magnetites, and that the interacting and middle‐coercivity components represent terrigenous maghemites. The ratio of anhysteretic remanent magnetization susceptibility to saturation IRM reflects relative abundance of the biogenic and terrigenous components. It was revealed that biogenic magnetites are a dominant constituent of the magnetic minerals. In glacials, the abundance of both biogenic and terrigenous components increased with increased proportions of the latter. Increased ocean productivity in glacials is suggested from increased proportions of biogenic magnetites with elongated morphologies, indicative of less‐oxic conditions, and increased sedimentation rates. These observations suggest that the increased magnetic concentration in glacials in the Southern Ocean may be explained by iron fertilization; the production of biogenic magnetites was enhanced associated with increased ocean productivity, which was fueled by increased eolian dust flux.

Pleistocene terraces of the Vltava River in the Budějovice basin (Southern Bohemian Massif): New insights into sedimentary history constrained by luminescence data

We studied Quaternary sediments from the Budějovice basin in southern Bohemia, now being able to reconstruct the landscape formation of this area during the late Pleistocene. The main objective of this study was to map fluvial terraces of the rivers Vltava and Malše in the basin and to constrain their ages by luminescence dating. Topographic data from a high-resolution DEM in combination with lithological profiles of more than 1000 boreholes allowed identifying five terrace levels (BB 1 to BB 5) with bases ranging from 7m below to 26m above the recent mean water level of the Vltava River. For the lowermost terrace level BB 1, a consistent stratigraphy with ages ranging between 84.5±9.0ka and 7.9±0.8ka was constrained. Additionally, we obtained luminescence ages of alluvial fan and colluvial deposits, which allow us to better constrain the late Pleistocene sedimentation history of the study area. Based on the spatial distribution of derived ages, the terrace level BB 1 represents a complex sediment body incorporating more distinct packages of river aggradation. The presence of stacked fluvial deposits of Pleistocene age underneath the recent floodplain points to an ongoing subsidence or relative tectonic stability of the Budějovice basin during the late Pleistocene.

Late Pleistocene artefacts and fauna from Rusinga and Mfangano islands, Lake Victoria, Kenya

Surveys and excavations in 2009–2011 recovered fossil and artefact assemblages from late Pleistocene sediments on Rusinga and Mfangano islands (Lake Victoria, Kenya). Radiometric age estimates suggest that the Rusinga material dates to between 100 and 33 kya, whereas that from Mfangano may date to ≥35 kya. The preservation of a large and diverse suite of vertebrate fossils is unusual for Pleistocene sites in the Lake Victoria region and the composition of the faunal assemblages from both islands strongly suggest an open, arid, grassland setting very different from that found in western Kenya today. Middle Stone Age (MSA) artefacts from Rusinga and possible Later Stone Age (LSA) or MSA/LSA assemblages from Mfangano are distinct from Lupemban MSA sites characteristic of the Lake Victoria region and instead share a number of typological and technological features with late Pleistocene sites from open grassland settings in the East African Rift System. This highlights the complex roles that shifting environments, as well as temporal change, may have played in the development of regional variation among Equatorial African artefact assemblages in the Pleistocene.