pinecone/core-2020-05-10-deduplication huggingface dataset:
Reconstructed centennial variability of Late Holocene storminess from Cors Fochno, Wales, UK

Future anthropogenic climate forcing is forecast to increase storm intensity and frequency over Northern Europe, due to a northward shift of the storm tracks, and a positive North Atlantic Oscillation. However understanding the significance of such a change is difficult because the natural variability of storminess beyond the range of instrumental data is poorly known. Here we present a decadal-resolution record of storminess covering the Late Holocene, based on a 4-m-long core taken from the peat bog of Cors Fochno in mid-Wales, UK. Storminess is indicated by variations in the minerogenic content as well as bromine deposited from sea spray. Twelve episodes of enhanced storm activity are identified during the last 4.5 cal ka BP. Although the age model gives some uncertainty in the timings, it appears that storminess increased at the onset and close of North Atlantic cold events associated with oceanic changes, with reduced storm activity at their peak. Cors Fochno is strongly influenced by westerly moving storms, so it is suggested that the patterns were due to variations in the intensity of westerly airflow and atmospheric circulation during times when the latitudinal temperature gradient was steepened. Document embargo 03/07/2016.authorsversionPeer reviewe
Potential for Southern Hemisphere climate surprises

Climate model results suggest that future climate change in Antarctica will be accompanied by continued strengthening and poleward contraction of the Southern Ocean westerly wind belt. Paleoclimate records suggest past changes in the westerly winds can be abrupt and that healing of the Antarctic ozone hole could lead to poleward contraction of the westerlies and increased meridional atmospheric transport of warm air regionally into Antarctica. An abrupt shift to more meridional circulation could lead to notable changes in moisture availability for extra-Antarctic regions, increased Antarctic ice sheet disintegration and more rapid sea-level rise
Lateglacial to Holocene relative sea-level changes in the Stykkishólmur area, northern Snæfellsnes, Iceland.

Comparatively little research has been undertaken on relative sea-level (RSL) change in western Iceland. This paper presents the results of diatom, tephrochronological and radiocarbon analyses on six isolation basins and two coastal lowland sediment cores from the Stykkishólmur area, northern Snæfellsnes, western Iceland. The analyses provide a reconstruction of Lateglacial to mid-Holocene RSL changes in the region. The marine limit is measured to 65–69 m above sea level (asl), with formation being estimated at 13.5 cal ka BP. RSL fall initially occurred rapidly following marine limit formation, until ca. 12.6 cal ka BP, when the rate of RSL fall decreased. RSL fell below present in the Stykkishólmur area during the early Holocene (by ca. 10 cal ka BP). The rates of RSL change noted in the Stykkishólmur area demonstrate lesser ice thicknesses in Snæfellsnes than Vestfirðir during the Younger Dryas, when viewed in the regional context. Consequently, the data provide an insight into patterns of glacio-isostatic adjustment surrounding Breiðafjörður, a hypothesized major ice stream at the Last Glacial Maximum
A multiproxy (micro-XRF, pollen, chironomid and stable isotope) lake sediment record for the Lateglacial to Holocene transition from Thomastown Bog, Ireland

A multiproxy Lateglacial environmental record is presented for a ca. 3.5-m lacustrine sequence retrieved from a small basin (ca. 2 km2) at Thomastown Bog in County Meath, Ireland. Sediment chemistry, pollen, chironomid and stable isotope data provide a detailed picture of catchment and lake system changes from the end of the last glacial (GS-2a) to the early Holocene that correspond closely to existing local and regional models of climate change. Concomitant adjustments in independent proxy records are matched to the NGRIP oxygen isotope curve giving 12 event-episodes ranging from major climatic shifts to lower amplitude, centennial- to sub-centennial-scale adjustments, including a previously unreported regressive period of landscape instability during the north-west European ‘Rammelbeek Phase’. The study emphasizes the potential of palaeoenvironmental reconstruction from sediment chemistry where the sediment mixing system reflects autochthonous versus allochthonous inputs. The investigation also indicates problems of interpreting isotope data derived from bulk marl due to possible lag effects controlling the delivery of soil and groundwater and multiple sources of HCO3– (aq.). These research findings have implications for core site selection and for studies attempting to use stable isotopes for correlation purposes.\u
Drumlin sedimentology in a hard-bed, lowland setting, Connemara, western Ireland : implications for subglacial bedform generation in areas of sparse till cover.

Cores of coastal drumlins in Connemara contain stratified diamictons that interdigitate with gravelly clinoforms and finer grained rhythmites. The diamictons are interpreted as subaqueous mud apron deposits delivered by subglacial till advection to continuously failing subaqueous ice-contact fans, whose strata were being syn-depositionally over-steepened by glacitectonic deformation. The localized nature of the stratified sediments reflects the emergence of subglacial deforming tills and meltwater deposits in a glacilacustrine environment to produce interdigitated mass flow diamictons and grounding line fans/wedges. These depo-centres became glacitectonized and subglacially streamlined during glacier overriding and hence regional drumlin sedimentology reflects the varying degrees of inheritance of pre-existing glacigenic deposits and suggests that drumlin production relates more to the position of localized sediment accumulations at the glacier bed than full-depth till deformation processes (e.g. instability mechanisms) within the same drumlin field. Till cored drumlins give way down ice to stratified cored drumlins with till caps and then to stratified drumlins. This zonation is compatible with the increased lateral variability in drumlin composition that would arise from the occurrence of linear assemblages of glacifluvial (esker) and subaqueous (grounding line) sediments in an otherwise marginal-thickening till sheet
Chronological variations in handaxes : patterns detected from fluvial archives in north-west Europe.

The use of handaxe morphology as a cultural and temporal marker within the Quaternary Lower–Middle Palaeolithic record has had a very chequered history, and abuses in the past have led recent generations of archaeologist to reject it out of hand. In Britain, however, advances in dating Pleistocene sediments, setting their ages within a framework of ∼11 glacial–interglacial cycles over the past 1 Ma, has revealed several patterns in technology and morphology that must be related to changing practices and cultural preferences over time. These are not predictable, nor are they linear, but nevertheless they may aid understanding of the movements of different peoples in and out of Britain over the past 500 000 years. It is also clear that such patterns are to be expected over a much wider region of the nearby continent, although they might not be identical, or even similar, to those established for southern Britain. This paper extends from explanation of the British patterns to an exploration of the extent to which something comparable can be recognized in neighbouring areas of continental Europe: a baseline for a planned collaborative survey of data from the Acheulean of north-west European river systems
A Marine Isotope Stage 4 age for Pleistocene raised beach deposits near Fethard, southern Ireland.

Raised beach deposits around the Irish coast have been interpreted as interglacial or last glacial in age. On the south coast of Ireland, the Courtmacsherry Formation raised beach (CFB), near Fethard, County Wexford, was dated using optically stimulated luminescence (OSL). This site was previously dated to Marine Isotope Stage (MIS) 6–5, but more recent dating of the CFB elsewhere along the south coast shows it is considerably younger (MIS 4–3). The OSL analyses in this paper aimed to determine if new dating would support the greater age of the Fethard raised beach or realign it with the CFB. The new OSL ages place the formation of the Fethard raised beach between 57 ± 6 and 45 ± 6 ka, with 53 ± 5 ka the most likely age if a single depositional event is assumed. This is consistent with OSL dates of the CFB elsewhere. An MIS 4–3 age has important implications in understanding the palaeogeography and timing of glaciation in Ireland, and requires a reassessment of regional relative sea level history. As the eustatic response to global ice volume resulted in lowered relative sea level during MIS 4–2, a crustal response to glaciation is implied by the new dates
A late Pleistocene-Holocene multi-proxy record of palaeoenvironmental change from Still Bay, southern Cape coast, South Africa

The file associated with this record is under a 12-month embargo from publication in accordance with the publisher's self-archiving policy, available at http://olabout.wiley.com/WileyCDA/Section/id-820227.html. The full text may be available through the publisher links provided above.The southern Cape is a key focus for southern Africa palaeoenvironmental research as it represents the transitional region between temperate westerlies and sub-tropical rainfall sources. This study presents pollen, plant biomarker, geochemical and charcoal data preserved in the Rietvlei wetland. The bulk of the record spans the last 16 kyr, but it also provides rare insights into late MIS 3 (c. 35-30k cal a BP). The data suggest that during the Pleistocene the development and permanence of this wetland was likely influenced by sea-level change via control on the local water table; notably lower sea levels within MIS 2 resulted in very limited wetland productivity. The MIS 3 section provides evidence both supporting previous suggestions of relatively humid conditions, but also some indication of periodic arid phases. The Holocene record suggests clear contrasts between the early (11-7k cal a BP – relatively humid), mid-Holocene (7-3.3k cal a BP; more arid, less productive wetland conditions) and latest Holocene (last 2k cal a BP resurgence in both fynbos and aquatic/riparian pollen). While isolating the roles of winter/summer rainfall remains challenging, these data clarify the nature of change during key episodes in the regional palaeoenvironmental record.Peer-reviewedPost-prin
Evidence for late Middle Pleistocene glaciation of the British margin of the southern North Sea.

The timing and extent of late Middle Pleistocene glaciations in England and the southern North Sea are controversial topics. The recent Trent Valley Palaeolithic Project uncovered evidence for a post-Anglian, pre-Devensian glaciation that affected much of central and eastern England; the Wragby Till of Lincolnshire is associated with this glacial event, attributed here to Marine Oxygen Isotope Stage (MIS) 8. Coeval glacigenic deposits in the Middle Trent suggest that both western and eastern lobes of MIS 8 ice reached the Derby area. These various deposits have been assigned previously to MIS 12, 10 or 6, although the last can be excluded for the Wragby Till, which is overlain by Trent terrace deposits assigned to MIS 7 (from biostratigraphy and amino acid dating). The disposition of these glacigenic deposits within the landscape, particularly in relation to terrace deposits of the ancestral River Trent, and the absence of MIS 11 and 9 deposits within the footprint of the glaciation also provide compelling evidence. At its maximum extent in eastern England the MIS 8 ice reached the Peterborough area; identifying its extension (or otherwise) into areas such as north-west Norfolk and the West Midlands requires further work
Mid-Pleistocene thin-skinned glaciotectonic thrusting of the Aberdeen Ground Formation, Central Graben region, central North Sea

This paper presents the results of a high-resolution 2D seismic survey of mid-Pleistocene glaciogenic sediments in the Central Graben region of the central North Sea. Sediments have undergone major glaciotectonic thrusting and folding associated with the repeated southerly advance of a mid-Pleistocene ice sheet. The total observed length of the thrust-stacked section is approximately 5–6 km, comprising a series of discrete thrust slices, which range in length from < 300 m to > 700 m. The basal detachment of the thrust complex occurs at a depth of ca. 220 m below the sea bed within the upper Aberdeen Ground Formation. A thin-skinned glaciotectonic model involving proglacial to ice-marginal glaciotectonic thrusting followed by post-tectonic deposition is proposed. Initial ice advance led to the over-pressurizing of groundwater within a laterally extensive sand sheet in the upper Aberdeen Ground Formation, promoting the formation of a major décollement surface at the base of the developing thrust-stack. Over-pressurization of the groundwater system is thought to have occurred in response to rapid ice advance, suggesting that the development of large-scale thrust complexes may be associated with surge-type behaviour. The proposed model evidences complex dynamics of mid-Pleistocene ice sheets within the central North Sea
Interpretation and application of carbon isotope ratios\ud
in freshwater diatom silica

Carbon incorporated into diatom frustule walls is protected from degradation enabling analysis for carbon isotope composition (δ13Cdiatom). This presents potential for tracing carbon cycles via a single photosynthetic host with well-constrained ecophysiology. Improved understanding of environmental processes controlling carbon delivery and assimilation is essential to interpret changes in freshwater δ13Cdiatom. Here relationships between water chemistry and δ13Cdiatom from contemporary regional data sets are investigated. Modern diatom and water samples were collected from river catchments within England and lake sediments from across Europe. The data suggest dissolved, biogenically produced carbon supplied proportionately to catchment productivity was critical in the rivers and soft water lakes. However, dissolved carbon from calcareous geology overwhelmed the carbon signature in hard water catchments. Both results demonstrate carbon source characteristics were the most important control on δ13Cdiatom, with a greater impact than productivity. Application of these principles was made to a sediment record from Lake Tanganyika. δ13Cdiatom co-varied with δ13Cbulk through the last glacial and Holocene. This suggests carbon supply was again dominant and exceeded authigenic demand. This first systematic evaluation of contemporary δ13Cdiatom controls demonstrates that diatoms have the potential to supply a record of carbon cycling through lake catchments from sediment records over millennial timescales
The Middle Pleistocene glacial evolution of northern East Anglia, UK: a dynamic tectonostratigraphic-parasequence approach

The Middle Pleistocene glacial history of northern East Anglia is a controversial topic with differing opinions surrounding chronology, provenance and the relative stratigraphic framework. Reconciling the stratigraphic framework of the region is an essential first step to developing onshore–offshore geological models and a robust event-driven chronological framework. Within this study a dynamic tectonostratigraphic–parasequence methodology is applied to deposits traditionally attributed to the Anglian Glaciation (Marine Isotope Stage 12). This approach offers an insight into ice-bed coupling during glaciation and how evolving boundary conditions influenced glacier dynamics. Six major tectonostratigraphic–parasequence assemblages (A1–A6) are recognized in northern East Anglia and correlate with successive advances into the region of North Sea or Pennine lobes of the British Ice Sheet. Individual tectonostratigraphic–parasequence assemblages are bound at their base by a sedimentary contact or, more commonly, a glacitectonic zone. The geometry and structural characteristics of these glacitectonic zones reflect temporal and spatial variations in ice-bed coupling (traction), a function of substrate rheology and, in turn, variations in lithology, porewater availability and thermo-mechanical properties. The role of permafrost may also be significant, promoting proglacial/ice-marginal thrust stacking in front of advancing ice and enhanced ice-bed decoupling during subsequent overriding and subglacial till accretio
The δ18O stratigraphy of the Hoxnian lacustrine sequence at Marks Tey, Essex, UK : implications for the climatic structure of MIS 11 in Britain.

Marine Isotope Stage 11 (MIS 11) is considered one of the best analogues for the Holocene. In the UK the long lacustrine sequence at Marks Tey, Essex, spans the entirety of the Hoxnian interglacial, the British correlative of MIS 11c. We present multiproxy evidence from a new 18.5-m core from this sequence. Lithostratigraphy, pollen stratigraphy and biomarker evidence indicate that these sediments span the pre-, early and late temperate intervals of this interglacial as well as cold climate sediments that post-date the Hoxnian. The δ18O signal of endogenic carbonate from this sequence produces several clear patterns that are interpreted as reflecting the climatic structure of the interglacial. As well as providing evidence for long-term climate stability during the interglacial and a major post-Hoxnian stadial/interstadial oscillation the δ18O signal provides strong evidence for abrupt cooling events during the interglacial itself. One of these isotopic events occurs in association with a short-lived increase in non-arboreal pollen (the NAP phase). The results presented here are discussed in the context of other MIS 11 records from Europe and the North Atlantic, particularly with respect to our understanding of the occurrence of abrupt climatic events in pre-Holocene interglacials
Early-Mid Pleistocene environments in the Valsequillo Basin, Central Mexico: a reassessment

The Valsequillo Basin in Central Mexico has been of interest due to the presence of megafaunal remains and evidence for early human occupation, but research has been controversial. It has been suggested that extensive and deep lakes characterized the Early Pleistocene environment but sediment exposure is highly fragmentary and reliable dating has been difficult. Here we report, for the first time, Early Pleistocene palaeoenvironmental reconstructions using stable isotopes, diatoms, tephra and pollen. We studied several stratigraphic sections of mainly non-volcanic rocks, containing the 1.3-Ma Xalnene Ash as a stratigraphic marker. The isotope and other proxy data show that topographically low points in the basin were occupied by spring-fed, shallow water lakes during the Early–Mid Pleistocene, with a trend to drier conditions. The basin was a dynamic volcaniclastic environment during this period, with the production of the Toluquilla volcanic sequence and other rhyolitic–dacitic volcanic ashes interbedded with the lake sediments at the sections studied. There is no evidence from the sections for extensive and deep lakes before or after deposition of the Xalnene Ash. Wetter conditions in the basin during the Early Pleistocene would have made it attractive for megafauna
A tale of two lakes: a multi-proxy comparison of Lateglacial and Holocene environmental change in Cappadocia, Turkey

Individual palaeoenvironmental records represent a combination of regional-scale (e.g. climatic) and site-specific local factors. Here we compare multiple climate proxies from two nearby maar lake records, assuming that common signals are due to regional-scale forcing. A new core sequence from Nar Lake in Turkey is dated by varves and U–Th to the last 13.8 ka. Markedly dry periods during the Lateglacial stadial, at 4.3–3.7 and at 3.2–2.6 ka BP, are associated with peaks in Mg/dolomite, positive δ18O, elevated diatom-inferred electrical conductivity, an absence of laminated sediments and low Quercus/chenopod ratios. Wet phases occurred during the early–mid Holocene and 1.5–0.6 ka BP, characterized by negative δ18O, calcite precipitation, high Ca/Sr ratios, a high percentage of planktonic diatoms, laminated sediments and high Quercus/chenopod ratios. Comparison with the record from nearby Eski Acıgöl shows good overall correspondence for many proxies, especially for δ18O. Differences are related to basin infilling and lake ontogeny at Eski Acıgöl, which consequently fails to register climatic changes during the last 2 ka, and to increased flux of lithogenic elements into Nar Lake during the last 2.6 ka, not primarily climatic in origin. In attempting to separate a regional signal from site-specific ‘noise’, two lakes may therefore be better than one
Quaternary fossil fauna from the Luangwa Valley, Zambia.

This paper describes a large collection of Quaternary fossil fauna from the Luangwa Rift Valley, Zambia. Stone Age artefacts have been recovered from stratified fluvial contexts, but no in situ fossil faunas have yet been recovered. We report on 500 fossil specimens collected from the surface of point bars exposed seasonally along the banks of the main Luangwa River channel. We used non-destructive X-ray fluorescence analysis of the fossils' chemical signatures to determine whether they derive from one or many primary contexts, and the relationship between chemical signature and state of preservation. Specimens are identified to taxon (genus) to reconstruct palaeoenvironments and biochronology. A relatively wide range of taxa is identified, including a fossil hominin talus, described here. None of the fossils is positively attributable to extinct species, except a femur of an extinct Theropithecus reported in 2003. Although no additional extinct taxa were identified, some of the remains were attributable to genera that are not currently found in this region. The results suggest that most of the assemblage derives from sediments which are Middle Pleistocene or later, and that past environments in the Luangwa Valley may have differed from the habitat availability found today
Low-latitude Holocene hydroclimate derived from lake sediment flux and geochemistry

This study investigates hydrological responses to climatic shifts using sediment flux data derived from two dated palaeolake records in south-east Arabia. Flux values are generally low during the early Holocene humid period (EHHP) (∼9.0–6.4k cal a BP) although several short-lived pulses of increased detrital input are recorded, the most prominent of which is dated between ∼8.3 and 7.9k cal a BP. The EHHP is separated from the mid-Holocene humid period (MHHP) (∼5.0–4.3k cal a BP) by a phase of increased sediment flux and aridity, which began between ∼6.4 and 5.9k cal a BP and peaked between ∼5.2 and 5.0k cal a BP. The termination of the MHHP is marked by a phase of high detrital sediment flux between ∼4.3 and 3.9k cal a BP. While long-term shifts in climate are most likely linked to changes in the summer position of the Intertropical Convergence Zone and associated Indian and African monsoon systems, it is noted that the abrupt, short-term phases of aridity observed in both records are coeval with intervals of rapid climate change globally, which triggered non-linear, widespread landscape reconfigurations throughout south-east Arabia