pinecone/core-2020-05-10-deduplication huggingface dataset:
Application of stable carbon isotopes for reconstructing salt-marsh floral zones and relative sea level, New Jersey, USA

We investigated use of δ13C in bulk organic sediment to define the botanical origin of samples preserved in coastal sediment as a means to reconstruct relative sea level in New Jersey, USA. Modern transects at three sites demonstrated that low and high salt-marsh floral zones dominated by C4 species (Spartina alterniflora and Spartina patens) were associated with sediment δ13C values between −18.9‰ and −15.8‰ and occurred from mean tide level (MTL) to mean higher high water (MHHW). Brackish transitional settings vegetated by Phragmites australis with Iva fructescens and Typha sp. (C3 species) and freshwater upland samples (C3 species) were characterized by bulk sediment δ13C values of −27.0‰ to −22.0‰ and existed above MHHW. Parallel transects at one site suggested that intra-site variability was not discernible. The utility of δ13C values for reconstructing relative sea level in New Jersey is limited by an inability to differentiate between brackish sediments related to sea level and freshwater upland samples. To facilitate this distinction in a 4.4 m core, we used a multi-proxy approach (δ13C values with presence or absence of agglutinated foraminifera) to recognize indicative meanings for four sample types. Sediment with δ13C values greater than −18.9‰ was derived from a vegetated salt-marsh and formed between MTL and MHHW. Sediment with δ13C values less than −22.0‰ and containing agglutinated foraminifera formed in a brackish transitional zone between MHHW and highest astronomical tide (HAT). This is the narrowest elevational range of the four sample types and most precise sea-level indicator. Sediment with δ13C values less than −22.0‰ and lacking foraminifera can only constrain the upper bound of former sea level. Samples with intermediate values (−22.0‰ to −18.9‰) formed between MTL and HAT. Using these indicative meanings and radiocarbon dates, we suggest that a transition from brackish to salt-marsh δ13C values recorded in the core took approximately 350 years (from 1800 to 1450 cal. a BP)
New age constraints for the maximum extent of the last British-Irish Ice Sheet (NW sector)

This paper presents the first terrestrial age constraints from the outer continental shelf for the maximum extent of the NW sector of the last British–Irish Ice Sheet. Cosmogenic 10Be ages from eight glacially transported boulders on the island of North Rona show that the Late Devensian (Late Weichselian) British–Irish Ice Sheet overrode the island at its maximal stage and retreated c. 25 ka BP. These new dates, supported by other geological evidence, indicate that the north-western part of the ice sheet was most extensive between 27 and 25 ka BP, reaching the outer continental shelf during the global eustatic sea-level minimum at the Last Glacial Maximum
Interglacial intensity in the North Atlantic over the last 800,000 years : investigating the complexity of the mid-Brunhes Event (MBE).

The mid-Brunhes Event (MBE) represents a step-like increase, between Marine Isotope Stages (MIS) 13/11, in the intensity of interglacial warmth. A transect of palaeoclimatic records in the North Atlantic from 40°N to the Nordic Seas indicates strong differences in the expression of the MBE within this region. Between 40 and 56°N sea surface and air temperature records suggest that all interglacials of the past 800 000 years were characterized by similar levels of warmth, so there is no evidence for an MBE in these latitudes of the North Atlantic. North of 56°N there is increasing evidence for interglacials MIS 19–13 being cold relative to MIS 11–1. As most records of long-term interglacial diversity suggest the MBE is a global event the North Atlantic is clearly anomalous. Furthermore, the strong spatial difference in temperature conditions during interglacials MIS 19–13 in the North Atlantic means that the temperature gradient across this region would have been enhanced, in fact effectively doubled in magnitude, during this interval
Establishment of modern circulation pattern atc. 6000 cal a BP in Disko Bugt, central West Greenland : opening of the Vaigat Strait.

Variations in the Holocene circulation of the West Greenland Current (WGC) in the Disko Bugt region have been reconstructed from a suite of sediment cores. Palaeoceanographic proxies include magnetic susceptibility (MS) and X-ray fluorescence titanium counts, which document a major shift in circulation at c. 6000 cal a BP. Before this date, sediments in southern Disko Bugt were characterized by high terrigeneous and basaltic input, suggesting widespread influence of meltwater plumes. Our data show that the WGC re-circulated in the southern Disko Bugt area because a potential northern pathway, the narrow Vaigat Strait, was blocked by icebergs that calved from marine outlet glaciers in eastern Disko Bugt. Sediments in southern Disko Bugt deposited after c. 6000 cal a BP have significantly lower terrestrial and basaltic sediment input, which coincides with minimum Holocene ice sheet extent. The reduced meltwater and iceberg discharge to the embayment caused the Vaigat Strait to become free of blocking icebergs and terrigenous input was partly diverted to the outer shelf. Thus, the modern circulation pattern of the WGC was established in the Disko Bugt region through the opening of the Vaigat Strait c. 6000 cal a BP
Apparent OSL ages of modern deposits from Fåbergstølsdalen, Norway : implications for sampling glacial sediments

This work was funded by NERC, grant number F008589/1The application of optically stimulated luminescence (OSL) dating within glacial settings can be limited where sediments have not had their OSL signal fully reset by sunlight exposure. Heterogeneous bleaching can result in age overestimations, and although it is recognized that certain depositional settings are more likely to have experienced sufficient sunlight exposure to bleach the OSL signal, no comprehensive study has empirically investigated the processes of sediment bleaching, or the variability in bleaching between deposits of the same type and within the same glacial catchment. A suite of modern glacial and glaciofluvial sediments from Fåbergstølsdalen, southern Norway, have been analysed to explore the controls that sedimentary processes and depositional setting have on bleaching of the OSL signal of quartz. There is considerable variability in the residual OSL ages of similar modern deposits, which reflects high sensitivity of the OSL signal to sediment source, sedimentary process, transport distance and depositional setting. Overdispersion values are greatest for the sediments which have been most heterogeneously bleached and these sediments have the lowest residual ages. Sampling strategies that incorporate sufficient consideration of the depositional framework of sample settings can minimize the effects of unbleached residuals on OSL age determinations.Publisher PDFPeer reviewe
The evolution of periglacial patterned ground in East\ud
Anglia, UK

During the Late Pleistocene, East Anglia experienced multiple cycles of periglacial activity. This research investigates whether chalkland patterned ground infilled with coversand developed during one or more glacial cycles or only during the last period of intensive periglacial activity to affect lowland Britain. Single grain luminescence ages from polygons and stripes at six sites in East Anglia suggest that the patterns experienced multiple phases of activity during the last 90–10 ka but do not date back to earlier glacial cycles. This activity is attributed to four main phases: (1) ∼55–60 ka, (2) ∼31–35 ka, (3) ∼20–22 ka and (4) ∼11–12 ka. Most sites show some activity around the Greenland Stadial 2a and the Younger Dryas Stadial, but polygons show a longer, more temporally and spatially varied record than stripes. Interpreted phases of activity mostly coincide with stadials within the last glacial–interglacial cycle, possibly at the end of climatic cold phases.\u
Late Holocene paleoseismology of a site in the region of maximum submergence during the 1964 Mw 9.2 Alaska earthquake.

Sediment archives of coseismic deformation from regions of maximum coseismic displacement act as key datasets for the development and constraint of models of surface elevation change associated with Holocene great earthquakes. We present new lithologic and biostratigraphic investigations of a previously thought lost core from Portage, at the head of Turnagain Arm, upper Cook Inlet, which is within the zone of maximum coseismic subsidence during the AD 1964 Alaska earthquake. Quantitative analysis of diatoms preserved over six peat–silt couplets before the AD 1964 earthquake show six phases of rapid relative sea-level rise. Radiocarbon dates from each contact show that all six correlate with independently modelled ages of great earthquakes recorded in the Prince William Sound segment of the Aleutian megathrust during the last 4000 years. As with the other sites in the upper Cook Inlet, there is no evidence for an earthquake between the penultimate great earthquake, ∼880 a BP, and AD 1964 in contrast to those separately recorded at Kodiak Island and Katalla. Correlation of the six earthquakes at Portage with those at Girdwood, and no evidence for additional peat–silt couplets, support our previous interpretation that the extra three peat–silt couplets at Girdwood lacking evidence of intertidal sedimentation represent local-scale changes in environment rather than coseismic subsidence and short recurrence intervals of great earthquakes
The effect of species on lacustrine δ18Odiatom and its implications for palaeoenvironmental reconstructions

The oxygen isotope composition of diatom silica (δ18Odiatom) is increasingly being used to reconstruct climate from marine and lacustrine sedimentary archives. Although diatoms are assumed to precipitate their frustule in isotopic equilibrium with their surrounding water, it is unclear whether internal processes of a given species affect the fractionation of oxygen between the water and the diatom. We present δ18Odiatom data from two diatom size fractions (3–38 and >38 µm) characterized by different species in a sediment core from Heart Lake, Alaska. Differences in δ18Odiatom between the two size fractions varies from 0 to 1.2‰, with a mean offset of 0.01‰ (n = 20). Fourier transform infrared spectroscopy confirms our samples consist of pure biogenic silica (SiO2) and δ18Odiatom trends are not driven by contamination. The maximum offset is outside the range of error, but the mean is within analytical error of the technique (± 1.06‰), demonstrating no discernible species-dependent fractionation in δ18Odiatom. We conclude that lacustrine δ18Odiatom measurements offer a reliable and valuable method for reconstructing δ18Owater. Considering the presence of small offsets in our two records, we advise interpreting shifts in δ18Odiatom only where the magnitude of change is greater than the combined analytical error.\u
Testate amoebae as a proxy for reconstructing Holocene water table dynamics in southern Patagonian peat bogs

Funded by Natural Environment Research Council. Grant Numbers: NE/I022809/1, NE/I022981/1, NE/I022833/1, NE/I023104/1 Ricardo Muza and the Wildlife Conservation Society Karukinka Park Acknowledgements This work was supported by the Natural Environment Research Council (grant numbers NE/I022809/1, NE/I022981/1, NE/I022833/1 and NE/I023104/1). We thank Ricardo Muza and the Wildlife Conservation Society (WCS) Karukinka Park rangers for facilitating access to Karukinka Park. We also thank François De Vleeschouwer, Gaël Le Roux, Heleen Vanneste, Sébastien Bertrand, Zakaria Ghazoui and Jean-Yves De Vleeschouwer for fieldwork assistance. Nelson Bahamonde (INIA, Punta Arenas, Chile) and Ernesto Teneb (UMag, Punta Arenas, Chile) provided logistical support for the fieldwork in Chile. Dr Andrea Coronato (CADIC, Ushuaia) kindly provided logistical support for the research in Argentina. Thanks to Jenny Johnston for cartography, David Jolley for assistance in microscopic photography and Audrey Innes for laboratory assistance. We highly appreciate reviews by Matt Amesbury and an anonymous reviewer. R.P. is supported by an Impact Fellowship from the University of Stirling.Peer reviewedPublisher PD
The use of multivariate statistics to resolve multiple contamination signals in the oxygen isotope analysis of biogenic silica

Analysis of the oxygen isotope composition (δ18O) of diatom silica is a commonly used tool for palaeoclimate reconstruction that recent studies have demonstrated may be complicated by the presence of non-diatom detrital material. Such contamination can mask any true climate-driven signal, leading to spurious results. Analysis of the 2.6-Ma Barsemoi diatomites from the East African Rift Valley highlights the presence of both tephra and clay in purified samples. Here we present a new method for assessing the relative contribution and geochemical composition of contamination components where sedimentary samples may be affected by more than one type of contamination. This approach shows that the incorporation of analytical techniques, such as X-ray fluorescence spectrometry, coupled with statistical modelling, can be used to develop a three end-member model to successfully resolve climate-driven changes in δ18Odiatom. Mass-balance corrections made to δ18Odiatom data demonstrate the importance of adopting quantitative geochemical analysis in tandem with the δ18O analysis of biogenic silica, to obtain accurate and meaningful results for palaeoclimate reconstruction.\u
Using palaeoenvironmental DNA to reconstruct past environments: progress and prospects

Palaeoenvironmental DNA (PalEnDNA) is defined as ancient DNA (aDNA) originating from disseminated genetic material within palaeoenvironmental samples. Sources of PalEnDNA include marine and lake sediments, peat, loess, till, ice, permafrost, palaeosols, coprolites, preserved gut contents, dental calculus, tephras, and soils as well as deposits in caves/rockshelters and at archaeological sites. PalEnDNA analysis provides a relatively new tool for Quaternary and archaeological sciences and its applications have included palaeoenvironmental and palaeodietary reconstructions, testing hypotheses regarding megafaunal extinctions, human–environment interactions, taxonomic studies and studies of DNA damage. Because PalEnDNA samples comprise markedly different materials, and represent wide-ranging depositional and taphonomic contexts, various issues must be addressed to achieve robust, reproducible findings. Such issues include climatic and temporal limitations, the biological origin and state (free versus bound) of PalEnDNA, stratigraphic reliability, sterile sampling, ability to distinguish modern from aDNA signals, DNA damage and PCR amplification, DNA extraction methods, and taxonomic resolution. In this review, we provide a non-specialist introduction to the use of PalEnDNA for Quaternary and archaeological researchers, assess attributes and limitations of this palaeoenvironmental tool, and discuss future prospects of using PalEnDNA to reconstruct past environments
A glacial cryptic refuge in south-east Australia: human occupation and mobility from 36 000 years ago in the Sydney Basin, New South Wales

Excavations across a source-bordering dune overlooking the Hawkesbury River in north-west Sydney, Australia, suggest initial occupation of the region by at least 36 ka, with variable but uninterrupted use until the early Holocene; following abandonment, the site was then re-occupied by ∼3 ka. Along with a handful of other sites, the results provide the earliest reliable evidence of permanent regional populations within south-eastern Australia, and support a model in which early colonizers followed the coastal fringe with forays along the main river systems. The evidence is consistent with the demographic model of Williams, 2013 (Proceedings of the Royal Society Series B 280: 20130486), which suggested low, but established regional populations before the Last Glacial Maximum (LGM), a population nadir following the LGM and increasing use of the region from ∼12 to 8 ka. The site exhibits increased use at the onset and peak of the LGM, and provides an example of a cryptic refuge as defined by Smith, 2013 (The Archaeology of Australia's Deserts. Cambridge University Press: New York). Specifically, changing artefact densities and attributes show the site was used repeatedly, but for shorter periods through this time, and suggest it formed one of a series of key localities in a point-to-point (rather than home-base) subsistence strategy. This strategy was maintained until the site's abandonment in the early Holocene, despite changing population and climatic conditions through the Terminal Pleistocene
Vegetation and environments since the Last Glacial Maximum in the Southern Tablelands, New South Wales

Regional changes in vegetation and environment in the last 16 ka have been reconstructed from Micalong Swamp and Willigobung Swamp (35ө on the western Southern Tablelands of New South Wales (NSW). Micalong Swamp lies at 980?m above sea level (a.s.l.), which is close to the subalpine treeline at this latitude. Willigobung Swamp (780?m a.s.l.) approaches the modern ecotone between dry and wet montane forest formations. The sites are sensitive to shifts in temperature and precipitation and are the first reported pollen records from the western montane slopes of NSW. A radiocarbon-based chronology indicates that Micalong Swamp was a swampy, gravel floodplain surrounded by alpine grassland before 16.1 ka. Subalpine woodland may have become established at 1000?m by 16-14 ka. Organic fen sedimentation developed <11.8 ka at Willigobung, and ~11.7 ka at the higher elevation Micalong Swamp. Wet forest elements were present at both sites around 10 ka and persisted for 3-4 ka. Sedimentation in a shallow lake or fen between 10 and 8 ka supports this evidence for wetter conditions in the early Holocene. In the late Holocene an expansion of subalpine flora between 2.7 and 0.9 ka preceded by shallow lake/fen sedimentation is consistent with regional evidence for neoglacial cooling.Full Tex
Speleogenetic evidence from Ogof Draenen for a pre-Devensian glaciation in the Brecon Beacons, South Wales, UK

The British Isles have been affected by as many as 30 glaciations during the Quaternary. However, the evidence for pre-Devensian glaciations in upland regions is scarce. Understanding the extent and timing of earlier upland glaciations is essential for modelling the long-term evolution and sensitivity of the British Ice Sheet. Caves, being protected from surface erosion and weathering, can preserve evidence of earlier glaciations in the form of speleothem and sediment archives. The ∼70-km-long Ogof Draenen cave system in South Wales, UK, contains multiple cave levels related to changes in the surface topography and drainage during the past 0.5 Ma. The cave contains evidence of massive influxes of sediment that were sufficient to choke the cave and alter the underground drainage. Analysis of the cave sediments, passage morphology and geometry suggests the cave once acted as a subterranean glacial spill-way before being overridden by ice. Speleothem U-series data demonstrate that this sediment influx occurred before Marine Isotope State (MIS) 9, probably during the Anglian glaciation (MIS 12). Evidence from Ogof Draenen indicates the impact of subsequent glaciations on the landscape evolution of the region was minimal and that much of the surface topography dates from the Anglian
A combined biogeochemical and paleobotanical approach to study permafrost environments and past dynamics.

When investigating past peatland processes and related carbon cycle dynamics, it is essential to identify and separate different peat environments: bogs, fens and permafrost, and their historical plant assemblages. Bog peat layers contain relatively well-preserved plant material for palaeoecological examination, whereas fen and permafrost peats are often highly humified, which in turn constrains reconstructions of past plant assemblages. Here, we analysed the chemical composition of arctic peat plateau plants to create a local reference training-set of plant biomarkers. We then combined palaeobotanical, biogeochemical and chronological analyses to one permafrost peat sequence collected from the East European Russian tundra (67°03′N, 62°57′E) to investigate past peatland dynamics and to evaluate the performance of the biomarker method in a highly decomposed permafrost environment. The results show that the chronologically constrained macrofossil analysis provided most of the essential information about the peatland succession. However, a more robust reconstruction of the past peatland dynamics was achieved by combining palaeobotanical and biogeochemical data sets. The similarity of the lipid biomarker distributions of the arctic and boreal peatland plants also implies that any established modern biomarker training-set of peatland plants could be applied universally to palaeoecological studies on peat sediments
From pollen percentage to vegetation cover – evaluation ofthe Landscape Reconstruction Algorithm in western Norway

The Landscape Reconstruction Algorithm (LRA) with the two models REVEALS and LOVE is developed to transform pollen percentage data to vegetation cover. This paper presents the first study to evaluate LRA in a region with large topographic variations within a short distances. The REVEALS model estimates regional vegetation abundance based on pollen assemblages from large lakes (100–500 ha). Pollen surface samples from one large and 28 small lakes are used together with a combination of regionally derived pollen productivity estimates and available estimates from other regions of Europe. The results show a good relationship between REVEALS-estimated forest cover and vegetation abundance based on the CORINE land-cover data. The REVEALS results using various sets of pollen assemblages from small lakes were comparable to those using one large lake. Local vegetation abundance using the LOVE model was estimated around 26 lakes. For common taxa, such as Pinus and Poaceae, the LOVE-based estimates of plant abundance match well with the distance-weighted plant abundances based on vegetation maps. Our results indicate that the LRA approach is effective for reconstruction of long-term vegetation changes in western Norway and other regions with high topographic relief when no major gradients exist in the pollen data
Editorial: Quaternary revolutions

PublishedEditorialJournalEditorialThe QRA@50 meeting was organized by a team
of people including the editors, John Catt, Catherine Souch, Tom Hill,
Danni Pearce and a team of postgraduates and staff from the Royal
Geographical Society-Institute of British Geographers (RGS-IBG). It
was made possible by support from a number of sponsors, including
RGS-IBG, van Walt, Beta Analytic Ltd, the Natural History Museum,
Wiley-Blackwell and C3W (Climate Change Consortium of Wales).
We would like to thank the reviewers of all the papers for their
comments and suggested improvements to the papers