Dr Jonathan Dean: Stable Isotope Apprentice – January 2014
Jonathan Dean has recently joined NIGL for 2 years as an Isotope Apprentice, and will be working on a variety of projects in the Stable Isotope Group. He was previously based in the School of Geography, University of Nottingham, where his PhD research focused on oxygen isotope analysis of carbonates and diatoms and uranium-thorium dating of lake sediments from Nar Gölü in central Turkey.
Professor Melanie Leng to join major science review panel – October 2013
Melanie will join the NERC Peer Review College (NERC PRC) as a Core Panel Member from 1st January 2014. The Core panel members have lead responsibility for attending moderating Panel meetings to ensure consistency within and between different Panel areas and funding schemes.
Dr Sarah Bennett: Stable Isotope Research Geochemist – May 2013
Sarah joins NIGL to carry out research in areas of hydrochemistry, pollution studies and surficial and solid earth geochemistry. Sarah’s previous research focussed on the chemistry and biology of deep-sea hydrothermal systems. She joins us from California where she carried out two post docs, one in microbiology at the University of Southern California and one in geochemistry at the NASA Jet Propulsion Laboratory. She carried out her PhD research at the National Oceanography Centre, Southampton.
Dr Andrea Snelling: Isotope Apprentice – 2013
Andrea Snelling joins NIGL as an isotope apprentice to work on stable isotope analysis and mass spectrometry on a variety of projects.
June 2014 – Well done to Andi Smith on the successful defence of his PhD thesis: Speleothem Climate Capture – A Holocene Reconstruction of Northern Iberian Climate and Environmental Change.
An extensive 4 year cave monitoring program has been undertaken at Asiul Cave, a previously unstudied site in Cantabria (Spain). Monitoring indicates that this cave has the potential for long term speleothem development and that stalagmites are ideal for the reconstruction of palaeoclimatic conditions, including importantly palaeorainfall amount reconstruction. Two speleothem samples were therefore removed from the cave and analysed for a suite of geochemical proxies. Coeval oxygen isotope records from Asiul Cave indicate that northern Iberia has experienced considerable deviations in rainfall during the last 12,500 years. These high resolution records are strongly coupled with changes in other regionally important climate archives, helping to add to our understanding of northern Iberian climate evolution. The Asiul speleothem records however, go beyond explaining local changes in environmental conditions by exhibiting a strong coupling between atmospheric conditions, in the form of the North Atlantic Oscillation (NAO) and North
Atlantic Ocean circulation. These speleothem archives indicate that the NAO controls not only the positioning of atmospheric storm tracks throughout Europe but through interactions with the surface layer of the ocean can cause major changes in oceanic circulation. These NAO controlled changes in North Atlantic Ocean circulation have been shown to cause significant cooling within the northern North Atlantic and the southerly transport of ice rafted debris, with a millennial periodicity of ~1500 years. The Asiul cave speleothem record is one of the first convincing archives of a millennial scale NAO system which has the capacity to force changes in oceanic circulation. These speleothems also act to extend existing archives of the NAO back into the Younger Dryas; in doing so the Asiul records challenge our current understanding of NAO dynamics and the exact timing of initial NAO development.
Andi was supervised by Dr Peter Wynn and Prof Phil Barker at Lancaster University and Prof Melanie Leng and Dr Steve Noble at the BGS.
March 2014 – Congratulations to Annemarie Valentine on successfully defending her PhD thesis: An investigation into the seasonality of the Pliocene southern North Sea Basin: a sclerochronological approach.
The Pliocene world c. 5.3 Ma to c. 2.58 Ma exhibited a relatively stable climate with a
warmer global mean surface temperature than present-day by ~2 °C to 3 °C, and
palaeoclimate analysis from this interval is used to understand climate drivers in
Previous oxygen isotope thermometry investigations of Pliocene southern North Sea
Basin (SNSB) Aequipecten opercularis from the Coralline Crag Formation in Suffolk,
UK repeatedly reveal evidence of a cold-temperate climate regime. Contrastingly,
other biological proxies record a warm-temperate/sub-tropical regime.
This investigation concentrated on oxygen, carbon and microgrowth increment
widths (MIWS) of fossil shell material from Pliocene SNSB spanning an interval
of~4.4 Ma to ~2.5 Ma. The study sites included shallow marine Pliocene formations
from the western and eastern SNSB, the Ramsholt Member of the Coralline Crag
Formation, Suffolk UK, and the Luchtbal Sands and Oorderen Sands Members of
the Lillo Formation, Belgium, and the Oosterhout Formation in the Netherlands.
Oxygen isotopic palaeotemperature results showed cooler summer temperatures
than presently in the SNSB, which were reflective of a cool-temperate regime. There
was no evidence of warm-temperate or sub-tropical summer palaeotemperatures in
the Pliocene SNSB as suggested by other planktonic proxies. This investigation
discussed the possible causal factors for the cooler – than– expected winter and
summer palaeotemperatures in the 'warmer' Pliocene world as recorded by this
proxy. Discrepancies between the cool summer benthic palaeotemperatures from the
bivalves and the warmer sub-tropical or warm-temperate summer palaeotemperature
estimations from planktonic biological proxies was rectified by the application of a
theoretical summer stratification factor (SSF). However, rectifying the discrepancies
between cooler (cold-temperate) benthic winter palaeotemperatures and the warmer
winter palaeotemperatures from other proxies was difficult because stratification
does not occur during the winter. Dormancy behaviours in the warm– temperate –
sub–tropical organisms was proposed as a suitable mechanism to allow their
coexistence with the cool-tolerant bivalves, which were able to grow and feed
underneath the thermocline during the summer months. Therefore, the investigation
showed how the Pliocene SNSB exhibited a greater seasonality than occurs
presently in the SNSB.
The driver for the cooler winter temperatures in the Pliocene SNSB was not
identified. Localised explanations including continental wind effects, interannual
variations in MOC strength, and increased storm activity in the winter bringing cooler
water into the SNSB were all suggested as potential drivers. Global features of
climate including interglacial/glacial cycles and orbital forcing effects were factors
also proposed for the overall mixed palaeotemperature signal in the Pliocene SNSB.
Annemarie was supervised at University of Derby by Dr Andy Johnson and by Prof Melanie Leng at the BGS.
March 2014 – Congratulations to Hayley Manners on the successful defence of her thesis: A Multi-Proxy Study of the Palaeocene - Eocene Thermal Maximum in Northern Spain.
At the boundary between the Palaeocene and Eocene epochs (ca. 56 Ma) a significant global warming event, termed the Palaeocene-Eocene Thermal Maximum (PETM), occurred. Records of this event are characterised by a negative carbon isotope excursion (CIE) which has been associated with the release of thousands of petagrams of isotopically light carbon into the ocean-atmosphere system, initiating changes in the carbon cycle, the climate system, ocean chemistry and the marine and continental ecosystems. The amount of isotopically light carbon that was required to cause the event, its source and the rapidity of its release are, however, are still debated. This study uses δ13CTOC, δ13Cn-alkane, δ13<CCARB and palynological data to evaluate the PETM CIE in terms of the magnitude of the CIE in both continental and marine settings, rapidity of release and drawdown of carbon, and mobilisation of different organic matter (OM) pools as a response to the climate change. The sections studied span a continental to marine transect in northern Spain. This represents the first organic geochemical study of these PETM sections, one of the first comparisons of CIE magnitude between continental and marine sections within the same sediment routing system, and one of the first comparisons of the same OM proxies within different depositional
environments. The data suggest that different OM pools were mobilised in response to the PETM, with reworking of older material, soil residence times, and contemporaneous vegetation all contributing. CIE profile shapes predominantly suggest a rapid onset and recovery from the event. The magnitude of the CIE was also assessed. The current resolution of the data suggests that the differences between continental and marine CIE magnitudes could be minimal within a single sediment routing system, perhaps establishing a realistic CIE magnitude for the PETM, for use in future modelling scenarios.
Hayley’s main supervisor was Dr Stephen Grimes (Plymouth) and Prof Melanie Leng at BGS.
March 2014 – Congratulations to Jonathan Dean who gained his PhD entitled: Stable Isotope Analysis and U-Th Dating of Late Glacial and Holocene Lacustrine Sediments from Central Turkey.
Water is a politically sensitive resource in the Near East and water stress is increasing. It is therefore vital that there is a strong understanding of past hydrological variability, so that the drivers of change can be better understood, and so that the links between the palaeoclimate and archaeological records in this key region in the development of human civilisation can be investigated. To be of most use, this requires high resolution records and a good understanding of palaeoseasonality. A sediment sequence spanning ~14,000 years was retrieved from Nar Gölü, a lake in central Turkey. My thesis focussed in particular on oxygen isotope analysis of carbonates and comparing δ18Ocarbonate and δ18Odiatom data in order to examine palaeoseasonality. Due to the high resolution δ18Ocarbonate data, it was possible to show that the rapidity of the Younger Dryas to Holocene transition at Nar Gölü was similar to that seen in North Atlantic records and that centennial scale arid events in the Holocene seem to occur at the time of cold periods in the North Atlantic. Taken together, this suggests a strong teleconnection between the two regions. However, the longer duration of the aridity peaks ~9,300 and ~8,200 years BP at Nar Gölü, compared with the more
discrete cooling events at this time in the North Atlantic, suggest that there are additional controls on Near East hydroclimate. There is a multi-millennial scale trend of increasing δ18Ocarbonate values from the early to late Holocene. This ‘Mid Holocene Transition’ has previously been identified in the Near East, however here it is demonstrated that water balance and not a shift in the seasonality of precipitation was the primary cause. Finally, for the first time, the stability of Near East climate in the early Holocene is robustly demonstrated, suggesting that this could have been a key enabler of the development of agriculture at this time.
Jon was supervised at University of Nottingham by Dr Matthew Jones and Prof Sarah Metcalfe, at NIGL he was supported by Dr Stephen Noble and Prof Melanie Leng
December 2013 – congratulations to Sven Könitzer who was granted a doctorate for his PhD research entitled: Primary biological controls on UK Lower Namurian shale gas prospectivity: A step towards understanding a major potential UK unconventional gas resource.
Sven’s research is the first to analyse the abundance and type of organic matter preserved in deeper-water mudstones deposited in a Late Mississippian UK basin alongside a detailed sedimentological study to determine the key depositional processes and the palaeoenvironment. This study is a key step in understanding where, and why, organic matter is concentrated in fine-grained sedimentary rocks. Mudstones of this age, deposited across central and northern England, are known oil and gas source rocks and are currently the focus of attention for onshore shale gas exploration. Shale gas is formed from organic matter present during maturation and is mostly retained in the same rock formation.
Sven was supervised by Prof Sarah Davies (Leicester) and Prof Mike Stephenson, Prof Melanie Leng, and Dr Chris Vane at the BGS
A full list of publications can be found in the NIGL Annual Reports. This section
highlights some of our high-impact papers as they go to press. A full list of NERC staff publications and outputs can be found in the NERC Open Research Archive (NORA)
Geology – July 2014
The Paleocene–Eocene Thermal Maximum (PETM), ca. 56 Ma, was a major global environmental perturbation attributed to a rapid rise in the concentration of greenhouse gases in the atmosphere. Geochemical records of tropical sea-surface temperatures (SSTs) from the PETM are rare and are typically affected by post-depositional diagenesis. To circumvent this issue, we have analyzed oxygen isotope ratios (δ18O) of single specimens of exceptionally well-preserved planktonic foraminifera from the PETM in Tanzania (δ19°S paleolatitude), which yield extremely low δ18O, down to <–5‰. After accounting for changes in seawater chemistry and pH, we estimate from
the foraminifer δ18O that tropical SSTs rose by >3 °C during the PETM and may have exceeded 40 Â°C. Calcareous plankton are absent from a large part of the Tanzania PETM record; extreme environmental change may have temporarily caused foraminiferal exclusion.
Aze, T., Pearson, P.N., Dickson, A.J., Badger, M.P.S., Bown, P.R., Pancost, R.D., Gibbs, S.J., Huber, B.T., Leng, M.J., Coe, A.L., Cohen, A.S., and Foster, G.L. 2014. Extreme warming of tropical waters during the Paleoceneâ€“Eocene Thermal Maximu. Geology, 42.
The discovery of the mortal remains of King Richard III provide an opportunity to learn more about his lifestyle, including his origins and movements and his dietary history; particularly focussing on the changes that Kingship brought. We analysed bioapatite and collagen from sections of two teeth which formed during Richard's childhood and early adolescence, and from two bones: the femur (which averages long-term conditions), and the rib (which remodels faster and represents the last few years of life). We applied multi element isotope techniques to reconstruct a full life history. The isotopes initially concur with Richard's known origins in Northamptonshire but suggest that he had moved out of eastern England by age seven, and resided further west, possibly the Welsh Marches. In terms of his diet, there is a significant shift in the nitrogen, but not carbon isotope values,
towards the end of his life, which we suggest could be explained by an increase in consumption of luxury items such as game birds and freshwater fish. His oxygen isotope values also rise towards the end of his life and as we know he did not relocate during this time, we suggest the changes could be brought about by increased wine consumption. This is the first suggestion of wine affecting the oxygen isotope composition of an individual and thus has wider implications for isotope-based palaeodietary and migration reconstructions.
Lamb, A.L., Evans, J.E., Buckley, R., Appleby, J. 2014. Multi-isotope analysis demonstrates significant lifestyle changes in King Richard III. Journal of Archaeological Science, 48, 5–14.
The exploitation of marine molluscs by Mediterranean hunter-gatherers increased from the Upper Palaeolithic onwards, although their role in subsistence has rarely been investigated fully. An ideal area to address this issue is the archipelago of the Egadi Islands, most of which were isolated by Post-Glacial sea level rise. Here we report on the results of the study of the mollusc assemblage recovered during the 1972 excavations at Grotta d'Oriente, a cave on Favignana, occupied from the Late Pleistocene to the middle Holocene. Marine molluscs, including principally rocky shore intertidal gastropods (Patella and Osilinus), were taken to the cave for consumption throughout its occupation, sporadically in the early Mesolithic, but more frequently and throughout the year in the late Mesolithic and early Neolithic. Progressive isolation resulted in intensification of
shellfish exploitation, but not, however, in long-term over-exploitation of all intertidal marine gastropods, despite their vulnerability to human predation. The archaeozoological and isotopic data suggest that shellfish were a useful source of protein for the occupants of Grotta d'Oriente, but that the main role of marine molluscs was probably to provide nutrients not readily available in the terrestrial foods which constituted the bulk of the diet.
Marcello, M., Thomas, K., Crema, E.R., Leng, M.J. 2014. A matter of taste? Mode and periodicity of marine mollusc exploitation on the Mediterranean island of Favignana (Egadi Islands, Italy) during its isolation in the early Holocene. Archaeofauna, 23, 133-147.
International Journal of Earth Sciences – August 2014
Lake Ohrid (Macedonia/Albania) is the oldest extant lake in Europe and exhibits an outstanding degree of endemic biodiversity. Here, we provide new high–resolution stable isotope and geochemical data from a 10 m core (Co1262) through the Late Glacial to Holocene and discuss past climate and lake hydrology (TIC, δ13Ccalcite, δ18Ocalcite) as well as the terrestrial and aquatic vegetation response to climate (TOC, TOC/N, δ13Corganic, Rock Eval pyrolysis). The data identifies 3 main zones: (1) the Late Glacial–Holocene transition represented by low TIC and TOC contents, (2) the early to mid–Holocene characterised by high TOC and increasing TOC/N and (3) the Late Holocene–Present which shows a marked decrease in TIC and TOC. In general, an overall trend of increasing δ18Ocalcite from 9 ka to present suggests progressive aridification through the Holocene, consistent with previous records from Lake Ohrid and the wider Mediterranean region. Several proxies show commensurate excursions that imply the impact of short-term
climate oscillations, such as the 8.2 ka event and the Little Ice Age. This is the bes–dated and highest resolution archive of past Late Glacial and Holocene climate from Lake Ohrid and confirms the overriding influence of the North Atlantic in the north–eastern Mediterranean. The data presented set the context for the International Continental scientific Drilling Program Scientific Collaboration On Past Speciation Conditions in Lake Ohrid project cores recovered in spring–summer 2013, potentially dating back into the Lower Pleistocene, and will act as a recent calibration to reconstruct climate and hydrology over the entire lake history.
Lacey, J.H., Francke, A., Leng, M.J., Vane, C.H., Wagner, B. 2014. A high resolution Late Glacial to Holocene record of environmental change in the Mediterranean from Lake Ohrid (Macedonia/Albania). International Journal of Earth Sciences. DOI 10.1007/s00531-014-1033-6.
Peri-urban floodplains are an important interface between developed land and the aquatic environment and may act as a source or sink for contaminants moving from urban areas towards surface water courses. With increasing pressure from urban development the functioning of floodplains is coming under greater scrutiny. A number of peri-urban sites have been found to be populated with legacy landfills which could potentially cause pollution of adjacent river bodies. Here, a peri-urban floodplain adjoining the city of Oxford, UK, with the River Thames has been investigated over a period of three years through repeated sampling of groundwaters from existing and specially constructed piezometers. A nearby landfill has been found to have imprinted a strong signal on the groundwater with particularly high concentrations of ammonium and generally low concentrations of nitrate and dissolved oxygen. An intensive study of nitrogen dynamics through the use of N-species chemistry, nitrogen
isotopes and dissolved nitrous oxide reveals that there is little or no denitrification in the majority of the main landfill plume, and neither is the ammonium significantly retarded by sorption to the aquifer sediments. A simple model reveals that up to 15% of the ammonium loading at the study site and over the length of the reach could increase in-stream concentrations by nearly 40%. Catchment management plans that encompass floodplains in the peri-urban environment need to take into account the likely risk to groundwater and surface water quality that these environments pose.
Gooddy, D.C., Macdonald, D.M.J., Lapworth, D.J., Bennett, S.A., Griffiths, K.J. Nitrogen sources, transport and processing in peri-urban floodplains, Science of the Total Environment 494-495 (2014) 28-38.
We consider whether the Anthropocene is recorded in the isotope geochemistry of the atmosphere, sediments, plants and ice cores, and the time frame during which any changes are recorded, presenting examples from the literature. Carbon and nitrogen isotope ratios have become more depleted since the 19th century, with the rate of change accelerating after âˆ¼AD 1950, linked to increased emissions from fossil fuel consumption and increased production of fertiliser. Lead isotope ratios demonstrate human pollution histories several millennia into the past, while sulphur isotopes can be used to trace the sources of acid rain.
Radioisotopes have been detectable across the planet since the 1950s because of atmospheric nuclear bomb tests and can be used as a stratigraphic marker. We find there is isotopic evidence of widespread human impact on the global environment, but different isotopes have registered changes at different times and at different rates.
Stratigraphical Basis for the Anthropocene – June 2014
Humankind has pervasively influenced the Earth’s atmosphere, biosphere, geosphere, hydrosphere and cryosphere, arguably to the point of fashioning a new geological epoch, the Anthropocene. To constrain the Anthropocene as a potential formal unit within the Geological Time Scale, a spectrum of indicators of anthropogenically-induced environmental change is considered, and shown as stratigraphical signals that may be used to characterize an Anthropocene unit, and to recognize its base. This volume describes a range of evidence that may help to define this potential new time unit and details key signatures that could be used in its definition. These signatures include lithostratigraphical (novel deposits, minerals and
mineral magnetism), biostratigraphical (macro- and micro-palaeontological successions and human-induced trace fossils) and chemostratigraphical(organic, inorganic and radiogenic signatures in deposits, speleothems and ice and volcanic eruptions). We include, finally, the suggestion that humans have created a further sphere, the technosphere, that drives global change.
C.N. Waters, J.A. Zalasiewicz, M. Williams, M.A. Ellis and A.M. Snelling. 2014. A Stratigraphical Basis for the Anthropocene. Special Publication 395. http://nora.nerc.ac.uk/506924/.
International Journal of Earth Sciences – May 2014
Lake Ohrid (Macedonia/Albania) is the oldest extant lake in Europe and exhibits an outstanding degree of endemic biodiversity. Here, we provide new high-resolution stable isotope and geochemical data from a 10 m core (Co1262) through the Late Glacial to Holocene and discuss past climate and lake hydrology (TIC, δ13Ccalcite, δ18Ocalcite) as well as the terrestrial and aquatic vegetation response to climate (TOC, TOC/N, δ13Corganic, Rock Eval pyrolysis). The data identifies 3 main zones: (1) the Late Glacial–Holocene transition represented by low TIC and TOC contents, (2) the early to mid-Holocene characterised by high TOC and increasing TOC/N and (3) the Late Holocene–Present which shows a marked decrease in TIC and TOC. In general, an overall trend of increasing δ18Ocalcite from 9 ka to present suggests progressive aridification through the Holocene, consistent with previous records from Lake Ohrid and the wider Mediterranean region. Several proxies show commensurate excursions that imply the impact of
short-term climate oscillations, such as the 8.2 ka event and the Little Ice Age. This is the best-dated and highest resolution archive of past Late Glacial and Holoce climate from Lake Ohrid and confirms the overriding influence of the North Atlantic in the north-eastern Mediterranean. The data presented set the context for the International Continental scientific Drilling Program Scientific Collaboration On Past Speciation Conditions in Lake Ohrid project cores recovered in spring–summer 2013, potentially dating back into the Lower Pleistocene, and will act as a recent calibration to reconstruct climate and hydrology over the entire lake history.
Lacey, J.H., Francke, A., Leng, M.J., Vane, C.H., Wagner, B. 2014. A high–resolution Late Glacial to Holocene record of environmental change in the Mediterranean from Lake Ohrid (Macedonia/Albania). International Journal of Earth Sciences. DOI 10.1007/s00531-014-1033-6.
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 >38μm) 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.
Bailey, Hannah L.; Henderson, Andrew C.G.; Sloane, Hilary J.; Snelling, Andrea; Leng, Melanie J.; Kaufman, Darrell S. 2014. The effect of species on lacustrine δ18Odiatom and its implications for palaeoenvironmental reconstructions. Journal of Quaternary Science, 29 (4). 393-400.
The Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project is an international research initiative to study the influence of major geological and environmental events on the biological evolution of lake taxa. SCOPSCO drilling campaigns were carried out in 2011 and 2013. In 2011 we used gravity and piston coring at one of the five proposed drill sites, and in 2013 we undertook deep drilling with the Deep Lake Drilling System (DLDS) of Drilling, Observation and Sampling of the Earth's Continental Crust (DOSECC). In April and May 2013, a total of 2100 m sediments were recovered from four drill sites with water depths ranging from 125 to 260 m. The maximum drill depth was 569 m below the lake floor in the centre of the lake. By retrieving overlapping sediment sequences, 95% of the sediment succession was recovered. Initial data from borehole logging, core logging and geochemical measurements indicate that the sediment
succession covers >1.2 million years (Ma) in a quasi-continuous sequence. These early findings suggest that the record from Lake Ohrid will substantially improve the knowledge of long-term environmental change and short-term geological events in the northeastern Mediterranean region, which forms the basis for improving understanding of the influence of major geological and environmental events on the biological evolution of endemic species.
Wagner, B., Wilke, T., Krastel, S., Zanchetta, G., Sulpizio, R., Reicherter, K., Leng, M., Grazhdani, A., Trajanovski, S., Francke A., Lindhorst, K., Cvetkoska, A., Reed, J.M., Zhang, X., Lacey, J.H., Wonik, T., Baumgarten, H., Vogel, H. 2014. The SCOPSCO drilling project recovers more than 1.2 million years of history from Lake Ohrid. Scientific Drilling, 17, 19-29.
Climate of the Past – May 2014
The transboundary Lake Prespa (Albania/former Yugoslav Republic of Macedonia/Greece) has been recognized as a conservation priority wetland. The high biodiversity encountered in the catchment at present points to the refugial character of this mountainous region in the southwestern Balkans. A lake sediment core retrieved from a coring location in the northern part of the lake was investigated through sedimentological, geochemical, and palynological analyses. Based on tephrochronology, radiocarbon and electron spin resonance (ESR) dating, and cross correlation with other Northern Hemisphere records, the age model suggests that the basal part of core Co1215 reaches back to 92 ka cal BP. Here we present the responses of this mid-altitude site (849 m a.s.l.) to climate oscillations during this interval and assess its sensitivity to millennial-scale variability. Endogenic calcite precipitation occurred in marine isotope stages (MIS) 5 and 1 and is synchronous with periods of increased primary production (terrestrial and/or lacustrine). Periods of pronounced phytoplankton blooms (inferred from green algae and dinoflagellate concentrations) are recorded in MIS 5 and MIS 1 and
suggest that the trophic state and lake levels underwent substantial fluctuations. Three major phases of vegetation development are distinguished: the forested phases of MIS 5 and MIS 1 dominated by deciduous trees with higher temperatures and moisture availability, the open landscapes of MIS 3 with significant presence of temperate trees, and the pine-dominated open landscapes of MIS 4 and MIS 2 with lower temperatures and moisture availability. Our findings suggest significant changes in forest cover and landscape openness, as well as in the properties of the vegetation belts (composition and distribution) over the period examined. The study area most likely formed the upper limit of several drought-sensitive trees (temperate tree refugium) at these latitudes in the Mediterranean mountains.
Panagiotopoulos, K., Böhm, A., Leng, M.J., Wagner, B., Schäbitz, F. 2014. Climate variability over the last 92Ka in SW Balkans from analysis of sediments from Lake Prespa. Climate of the Past, 10, 643-660.
Journal Of Archaeological Science – May 2014
Two sets of well-preserved human footprints have been found in tufa sediments in the Cuatrociénegas Basin, NE Mexico, and here we present their U-series dates of 10.55 ± 0.03 ka and 7.24 ± 0.13 ka. The former are the oldest known footprints in Mexico, although their exact location is unknown, the latter form part of a trackway with eleven in situ human footprints. Oxygen (and to a lesser extent) carbon isotope data from the sediments suggest that the tufa with in situ footprints formed during a transition to a wetter (less arid) period, while pollen evidence indicates the basin floor presence of pecan (Carya) and willow (Salix sp.) before the onset of regional Chihuahuan Desert aridity.
These footprints confirm the presence of humans, possibly nomadic hunter–gatherer groups, which persisted until the 18th Century AD.
Feldstead, N.J., Gonzalez, S., Huddart, D., Noble, S.R., Hoffmann, D.L., Metcalfe, S.E., Leng, M.J., Albert, B.M., Pike, A.W.G., Gonzalez-Gonzalez, A., Jimenez-Lopez, J, C. 2014. Holocene-aged human footprints from the Cuatrocienegas Basin, NE Mexico. Journal of Archaeological Sciences, 42, 250-259.
Journal of Sedimentary Research – March 2014
Deep-water mudstones from ancient epicontinental settings are significant repositories for organic matter, but the detailed temporal variations of, and controls on, the abundance and type of organic matter (OM) is little studied. Using micro-petrographic and geochemical data from late Mississippian mudstones of the Widmerpool Gulf, UK, the processes that delivered fine-grained sediment to this basin during a glacioeustatic sea-level cycle are interpreted from detailed lithofacies analysis. Seven primary lithofacies are identified from core, which show specific and systematic variations in total organic carbon (TOC) content and bulk carbon isotope composition of organic material (δ13Corg). During sea-level highstands, thin-bedded carbonate-bearing mudstones are the dominant facies deposited, contain up to 6.6% TOC (average 4.6±1.3%), and have mean δ13Corg of &nda28.5±0.9‰. During phases of lower sea level, thin-bedded silt-bearing clay-rich mudstones with up to 4.1% TOC (average 2.3±0.8%; mean δ13Corg: –28.2±1.0‰) were interbedded with more organic-lean graded silt-bearing mudstones and sand-bearing silt-rich mudstones (average TOC: 1.7±0.6%) derived from turbidity currents. The latter (mean δ13Corg: –26.2±0.7‰) are closely linked to significant proportions of terrestrial plant material, while some rare plant debris- and sand-bearing mudstones produced from debris flows have more than 7.0% TOC and δ≥–26.0‰.
The δ13C values of wood fragments ranged from –27.1‰ to –24.0‰ and therefore the δ13Corg is interpreted as a function of the ratio of marine and terrestrial organic matter. More negative values in the carbonate-bearing and the clay-rich mudstones indicate marine planktonic algae whereas the least negative values reflect greater contribution of terrestrial plant material. The data suggest that the marine conditions prevailed and supported marine planktonic algae throughout different sea-level stages. Marine OM was delivered to the sea floor by continuous hemipelagic settling whereas terrestrial OM was delivered by sediment density flows. Variations in bioproductivity and dilution by siliciclastics influenced the burial rate of marine OM. Organic-rich mudstones preserved in these marine basins are potential hydrocarbon source rocks, especially as unconventional (shale gas) reservoirs. Detailed microtextural and compositional analysis coupled with rigorous geochemical parameters as used in this study are important for the understanding of the source-rock potential of basinal mudstones, and of fine-grained organic-rich sediments in general.
Konitzer, S.F., Davies, S.J., Stephensin, M.H., Leng, M.J. 2014. Depositional Controls On Mudstone Lithofacies In A Basinal Setting: Implications for the Delivery of Sedimentary Organic Matter. Journal of Sedimentary Research, 84, 198-214.
The 74 (75) ka Toba eruption in Sumatra, Indonesia, is considered to be one of the largest volcanic events during the Quaternary. Tephra from the Toba eruption has been found in many terrestrial and marine sedimentary deposits, and acidity peaks related to the eruption have been used to synchronize ice core records from Greenland and Antarctica. Seismic profiles and sedimentological data from Lake Prespa on the Balkan Peninsula, SE Europe, indicate a lake level lowstand at 73.6 ± 7.7 ka based on ESR dating of shells. Tephrostratigraphy, radiocarbon dating and tuning of the total organic carbon content with the NGRIP isotope record, corroborate that the lake level lowstand was a short-term event superimposed on the general cooling trend at the end of MIS 5, most likely at the onset of the Greenland Stadial GS-20. Acknowledging that tectonic events or karst
processes could have triggered this lake level lowstand, the chronological correspondence between the lowstand and the Toba eruption is intriguing. Therefore a Toba-driven short-term shift to aridity in the Balkan region, leading to lake level changes and triggering spatial expansion events in one of the lake's most abundant benthic species, the carino mussel Dreissena presbensis, cannot be excluded.
Citation: Wagner, B., Leng, M. J., Wilke, T., Böhm, A., Panagiotopoulos, K., Vogel, H., Lacey, J. H., Zanchetta, G., and Sulpizio, R.: Distinct lake level lowstand in Lake Prespa (SE Europe) at the time of the 74 (75) ka Toba eruption, Clim. Past, 10, 261-267, doi:10.5194/cp-10-261-2014, 2014.
Iron (Fe) oxidizing bacteria have the potential to produce morphologically unique structures that may be used as biosignatures in geological deposits. One particular example is Mariprofundus ferrooxydans, which produces extracellular twisted ribbon-like stalks consisting of ferrihydrite, co-located with organic and inorganic elements. It is currently thought that M. ferrooxydans excrete and co-precipitate polysaccharides and Fe simultaneously, however the cellular production of these polysaccharides has yet to be confirmed. Here, we report on a time series study that used scanning
transmission X-ray microscopy (STXM) and C 1s and Ca 2p near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy to investigate production of polysaccharides over the growth cycle of M. ferrooxydans.
Sarah A. Bennett, Brandy M. Toner, Roman Barco and Katrina J. Edwards. 2014. Carbon adsorption by Fe oxyhydroxide stalks produced by a lithotrophic iron-oxidizing bacteria. Geobiology DOI:10.1111/gbi.12074
The Limfjord region of northern Jutland, Denmark, supports a rich archaeological record dating back to the Mesolithic, which documents long-term change in human practices and utilisation of marine resources since approximately 7500 BP. The presence and availability of marine resources in the Limfjord is sensitively regulated by environmental parameters such as salinity, sedimentary regime, nutrient status and primary productivity, but long-term changes in these parameters are currently poorly understood. In this study a multiproxy approach (including sedimentary parameters, diatoms, molluscs, foraminifera, sedimentary pigments, C and O stable isotopes and plant macrofossils) has been adopted to assess environmental change over the period ca 7500–1500 cal yrs BP at Kilen, a coastal fjord (before AD 1856) situated in the Western Limfjord. A diatom-based salinity transfer function based on a pan-Baltic training set has been applied to the fossil diatom dataset for quantitative assessment of salinity change over the study period. This study demonstrates that large-scale shifts in salinity are a common feature of the Limfjord's long-term history and are driven by the level of connection with the North Sea and the Skagerrak respectively,
which in turn is likely driven by the complex interplay between climate, sea-level change, current velocity and rates of erosion/sedimentary accretion. Three shifts in state at Kilen are identified over the study period: a deep, periodically stratified fjord with medium–high salinity (and high productivity) between ca 7500–5000 BP, followed by a gradual transition to a shallow benthic system with more oceanic conditions (i.e. higher salinity, lower productivity, slower sedimentary accumulation rate and poorer fossil preservation) after ca 5000 BP and no stratification after ca 4400 BP, and lastly, within this shallow phase, an abrupt shift to brackish conditions around 2000 BP. Environmental–societal interactions are discussed on the basis of the data presented in this study and current environmental hypotheses for cultural change are challenged.
Jonathan P. Lewis, David B. Ryves, Peter Rasmussen Karen L. Knudsen, Kaj S. Petersen, Jesper Olsen, Melanie J. Leng, Peter Kristensen, Suzanne McGowan, Bente Philippsen. 2013. Environmental change in the Limfjord, Denmark (ca 7500–1500 cal yrs BP): a multiproxy study. Quaternary Science Reviews, 78, 126–140.
The Mg/Ca, Sr/Ca, δ18O and δ13C compositions are given for well-preserved specimens of ten belemnite species/genera from three stratigraphic intervals. The data help assess the use of these proxies for palaeo-oceanography. Samples are from Dorset, UK (Pliensbachian; 5 species); Cambridgeshire, UK (Callovian; 1 species); and the Vocontian Basin, SE France (Valanginian; 4 genera). In none of these belemnite populations (at species or genera level) does Mg/Ca correlate with δ18O. Neither do values of δ18O correlate with Mg/Ca along a microsampled radial profile across a single specimen of
Cylindroteuthis puzosiana (Callovian). The use of Mg/Ca is therefore considered to be unreliable as a palaeo-temperature indicator for these belemnite species and genera.
Q. Li, J.M. McArthur, P. Doyle, N. Janssen, M.J. Leng, W. Müller, S. Reboulet. 2013. Evaluating Mg/Ca in belemnite calcite as a palaeo-proxy. Palaeogeography, Palaeoclimatology, Palaeoecology, 388, 98-108.
Proceedings of the National Academy of Sciences – July 2013
The spread of farming from western Asia to Europe had profound long-term social and ecological impacts, but identification of the specific nature of Neolithic land management practices and the dietary contribution of early crops has been problematic. Here, we present previously undescribed stable isotope determinations of charred cereals and pulses from 13 Neolithic sites across Europe (dating ca. 5900–2400 cal B.C.), which show that early farmers used livestock manure and water management to enhance crop yields. Intensive manuring inextricably linked plant cultivation and animal herding and contributed to the remarkable resilience of these combined practices across diverse climatic zones. Critically, our findings suggest that commonly
applied paleodietary interpretations of human and herbivore δ15N values have systematically underestimated the contribution of crop-derived protein to early farmer diets.
Amy Bogaard, Rebecca Fraser, Tim H. E. Heaton, Michael Wallace, Petra Vaiglova, Michael Charles, Glynis Jones, Richard P. Evershed, Amy K. Styring, Niels H. Andersen, Rose-Marie Arbogast, László Bartosiewicz, Armelle Gardeisen, Marie Kanstrup, Ursula Maier, Elena Marinova, Lazar Ninov, Marguerita Schäfer, and Elisabeth Stephan. 2013. Crop manuring and intensive land management by Europe’s first farmers. PNAS doi: 10.1073/pnas.1305918110.
Global and Planetary Change – July 2013
Long (multi-millennial), continuous lake pollen records have provided insights into terrestrial ecosystem responses to orbital- and sub-orbital-scale climate forcing. By comparison, the potential of diatoms and stable isotopes to provide additional insights into limnetic response over comparable timescales has not been explored to the same extent, particularly in the Mediterranean region, even though such proxies are known to respond sensitively and rapidly to environmental change. Here we present a 19,000-year multiproxy record of limnetic change in the Ioannina basin, NW Greece, spanning the penultimate interglacial–glacial transition and the early penultimate glacial (c. 189–170 ka BP). The diatom record, the first from this interval in Southern Europe, reveals that lake conditions changed in concert with muted millennial-scale climate oscillations thought to originate in the North Atlantic, demonstrating clearly the sensitivity of diatoms to sub-orbital climate variability. Diatom and isotope-inferred changes in lake conditions coincided with the MIS 7/6 transition, whilst the new δ18O record suggests
increased moisture availability in SE Europe during MIS 6.5, adding support for a Mediterranean-wide increase in precipitation. Comparison with pollen data from the same sequence demonstrates that lake and terrestrial ecosystems co-varied, with no delay in forest expansion in response to climate change during this interval. Substantial changes in lake conditions contrast with subdued changes in catchment vegetation during an 8000 year-long cold interval in the early penultimate glacial. This may reflect differences in limnetic and terrestrial thresholds of response to environmental change, and perhaps also the influence of site specific factors in modulating terrestrial ecosystem response.
Wilson, Graham, Frogley, M., Roucoux, K., Jones, T., Leng, M., Lawson, I. and Hughes, P. (2013) Limnetic and terrestrial responses to climate change during the onset of the penultimate glacial stage in NW Greece. Global and Planetary Change, 107. pp. 213-225.
Journal of Paleolimnology – May 2013
Isotope geochemistry is an essential part of environmental and climate change research and over the last few decades has contributed significantly to our understanding of a huge array of environmental problems, not least in palaeolimnology and limnogeology. Here we describe some of the recent developments in the use of stable isotopes in palaeo-lake research. These are: better preparation, analysis, and interpretation of biogenic silica oxygen and silicon isotopes; extraction and characterisation of specific compounds such as leaf waxes and algal lipids for isotope analysis; determining the excess of 13C-18O bonds in
clumped isotopes; and the measurement of multiple isotope ratios in chironomid chitin. These advances have exciting prospects and it will be interesting to see how these techniques develop further and consequently offer a real advancement in our science over the next decade.
Leng, M.J. and Henderson, A.C.G. 2013. Recent advances in isotopes as palaeolimnological proxies. Journal of Paleolimnology, 49, 481-496.
Encyclopedia of Quaternary Science, 2nd Edition – April 2013
The second revised edition of the Encyclopedia of Quaternary Science, provides both students and professionals with an up-to-date reference work on this important and highly varied area of research. There are lots of new articles, and many of the articles that appeared in the first edition have been updated to reflect advances in knowledge since 2006, when the original articles were written.
Leng, M.J., Barker, P.A., Swann, G.E.A., Snelling, A.M. 2013. δ18O Records. In: Elias, S.A. (ed). The Encyclopedia of Quaternary Science, vol. 1, pp.481-488. Amsterdam: Elsevier.
Paleoceanography – April 2013
The development of a permanent, stable ice sheet in East Antarctica happened during the middle Miocene, about 14 million years (Myr) ago. The middle Miocene therefore represents one of the distinct phases of rapid change in the transition from the “greenhouse” of the early Eocene to the “icehouse” of the present day. Carbonate carbon isotope records of the period immediately following the main stage of ice sheet development reveal a major perturbation in the carbon system, represented by the positive δ13C excursion known as carbon maximum 6 (“CM6”), which has traditionally been interpreted as reflecting increased burial of organic matter and atmospheric pCO2 drawdown. More recently, it has been suggested that the δ13C excursion records a negative feedback resulting from the reduction of silicate weathering and an increase in atmospheric pCO2.
Here we present high-resolution multi-proxy (alkenone carbon and foraminiferal boron isotope) records of atmospheric carbon dioxide and sea surface temperature across CM6. Similar to previously published records spanning this interval, our records document a world of generally low (~300 ppm) atmospheric pCO2 at a time generally accepted to be much warmer than today. Crucially, they also reveal a pCO2 decrease with associated cooling, which demonstrates that the carbon burial hypothesis for CM6 is feasible and could have acted as a positive feedback on global cooling.
Badger M, Lear C, Pancost R, Foster G, Bailey T, Leng M, Abels H. 2013. CO2 drawdown following the middle Miocene expansion of the Antarctic Ice Sheet. Paleoceanography 28, 42–53.
Over the past 50 years, warming of the Antarctic Peninsula has been accompanied by accelerating glacier mass loss and the retreat and collapse of ice shelves. A key driver of ice loss is summer melting; however, it is not usually possible to specifically reconstruct the summer conditions that are critical for determining ice melt in Antarctic. Here we reconstruct changes in ice-melt intensity and mean temperature on the northern Antarctic Peninsula since AD 1000 based on the identification of visible melt layers in the James Ross Island ice core and local mean annual temperature estimates from the deuterium content of the ice. During the past millennium, the coolest conditions and lowest melt occurred from about AD 1410 to 1460, when mean temperature was 1.6°C lower than that of 1981–2000. Since the late 1400s, there has been a nearly tenfold increase in melt intensity from 0.5 to 4.9%.
The warming has occurred in progressive phases since about AD 1460, but intensification of melt is nonlinear, and has largely occurred since the mid-twentieth century. Summer melting is now at a level that is unprecedented over the past 1,000 years. We conclude that ice on the Antarctic Peninsula is now particularly susceptible to rapid increases in melting and loss in response to relatively small increases in mean temperature.
Nerilie J. Abram, Robert Mulvaney, Eric W. Wolff, Jack Triest, Sepp Kipfstuhl, Luke D. Trusel, FranÃ§oise Vimeux, Louise Fleet & Carol Arrowsmith. 2013. Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century. Nature Geoscience. Online.
The Antarctic Peninsula is one of the fastest-warming regions on Earth, but its palaeoenvironmental history south of 63° latitude is relatively poorly documented, relying principally on the marine geological record and short ice cores. In this paper, we present evidence of late-Quaternary environmental change from the Marguerite Bay region combining data from lake sediment records on Horseshoe Island and Pourquoi-Pas Island, and raised beaches at Horseshoe Island, Pourquoi-Pas Island and Calmette Bay. Lake sediments were radiocarbon dated and analysed using a combination of sedimentological, geochemical and microfossil methods. Raised beaches were surveyed and analysed for changes in clast composition, size and roundness. Results suggest a non-erosive glacial regime could have existed on Horseshoe Island from 35,780 (38,650–33,380) or 32,910 (34,630–31,370) cal yr BP onwards.
There is radiocarbon and macrofossil evidence for possible local deglaciation events at 28,830 (29,370–28,320) cal yr BP, immediately post-dating Antarctic Isotopic Maximum 4, and 21,110 (21,510–20,730 interpolated) cal yr BP coinciding with, or immediately post-dating, Antarctic Isotopic Maximum 2. The Holocene deglaciation of Horseshoe Island commenced from 10,610 (11,000–10,300) cal yr BP at the same time as the early Holocene temperature maximum recorded in Antarctic ice cores.
Late Quaternary environmental changes in Marguerite Bay, Antarctic Peninsula,inferred from lake sediments and raised beaches. (2013) Dominic A. Hodgson; Stephen J. Roberts; James A. Smith; Elie Verleyen; Mieke Sterken; Minke Labarqueb; Koen Sabbe; Wim Vyverman; Claire S. Allen; Melanie J. Leng; Charlotte Bryant. Quaternary Science Reviews 68: 216–236.
Journal of Climate – April 2013
Climate change west of the Antarctic Peninsula is the most rapid of anywhere in the Southern Hemisphere, with associated changes in the rates and distributions of freshwater inputs to the ocean. Here, results from the first comprehensive survey of oxygen isotopes in seawater in this region are used to quantify spatial patterns of meteoric water (glacial discharge and precipitation) separately from sea ice melt. High levels of meteoric water are found close to the coast, due to orographic effects on precipitation and strong glacial discharge. Concentrations decrease offshore, driving significant southward geostrophic flows (up to ~30 cm sâˆ’1).
These produce high meteoric water concentrations at the southern end of the sampling grid, where collapse of the Wilkins Ice Shelf may also have contributed. As the regional freshwater system evolves, the continuing isotope monitoring described here will elucidate the ongoing impacts on climate and the ecosystem.
Michael P. Meredith, Hugh J. Venables, and Andrew Clarke, Hugh W. Ducklow and Matthew Erickson, Melanie J. Leng, Jan T. M. Lenaerts and Michiel R. van den Broek. 2013. The Freshwater System West of the Antarctic Peninsula: Spatial and Temporal Changes. Journal of Climate, 26, p. 1669-1684.
Journal Quaternary Science Reviews – March 2013
Isotope geochemistry is increasingly an essential part of environmental and climate change research and now routinely contributes to our understanding of many critical environmental problems, which span the whole of Earth system science and not least in palaeolimnology and limnogeology. The International Association of Limnogeology organises an international conference every four years. The fifth International Limnogeology Congress, ILIC V, was held in Konstanz, Germany, from August 31st - September 3rd, 2011. During this congress we identified several papers where isotope methodologies were used in a particularly novel way, or provided an ‘added value’ data set.
Many of these are brought together in this volume as a series of state-of-the-art papers dealing with various aspects of isotopes in lake sediment archives. These papers are themed under isotopes in contemporary processes, isotopes in diatom silica from lake sediments, isotopes in organic materials in lake sediments, and isotopes in carbonates from lake sediments. The journal editors of this volume are Prof Melanie J. Leng (British Geological Survey and University of Leicester), Prof Phillip A. Barker (Lancaster University) and Prof Antje Schwalb (Universität Braunschweig,Germany).
The Early Jurassic Epoch was a predominantly greenhouse phase of Earth history, but a comprehensive understanding of its climate dynamics is hampered by a lack of high resolution multi-proxy environmental records. Here we report a geologically brief (approximately several hundred thousand years) negative carbon isotope excursion in both marine and terrestrial materials, recognised for the first time for the Late Sinemurian Substage (Early Jurassic, ~194 Ma) of eastern England. The Late Sinemurian carbon isotope excursion,
which is termed the S-CIE, is accompanied by peaks in the abundance of various pollen grains...
Riding, J.B., Leng, M.J., Kender, S., Hasselbo, S.P., Feist-Burkhardt, S. 2013. Isotopic and palynological evidence for a new Early Jurassic environmental perturbation. Palaeogeography, Palaeoclimatology, Palaeoecology, 374, 16-27.
The current issue of Elements Magazine is entitled ‘100 years of Isotope Geochronology’ and is co-edited by Dr Dan Condon (NIGL) and includes a several papers co-authored by Dan Condon and Matt Horstwood.
Earth and Planetary Science Letters – January 2013
Understanding the response of the Antarctic ice sheets during the rapid climatic change that accompanied the last deglaciation has implications for establishing the susceptibility of these regions to future 21st Century warming. A unique diatom δ18O record derived from a high-resolution deglacial seasonally laminated core section off the west Antarctica Peninsula is presented. By extracting and analysing single species samples from individual laminae, season-specific isotope records were separately generated to show
changes in glacial discharge (comprised of both glacial and iceberg sourced meltwater) to the coastal margin during spring and summer months...
Swann, G.E.A., Pike, J., Snelling, A.M., Leng, M.J., Williams, M.C. 2013. Seasonally resolved diatom δ18O records from the West Antarctica Peneinsula over the last deglaciation. Earth and Planetary Science Letters, 364, 12-23.
This paper describes a multi-proxy palaeoecological investigation of lake sediments undertaken in conjunction with an archaeological survey of the Upper Sangro Valley in the Abruzzo National Park, Central Italy. The data show how cultural factors had a profound effect on this mountainous region which, in this case, outweighed the effects of climatic fluctuations which are known to have occurred locally and across the wider region. These findings have positive implications for the
conservation of top predators which require large wooded ranges.
Brown, A.G., Hatton, J., Selby, K.A., Leng, M.J., Christie, N. 2013. Multi-proxy study of Holocene environmental change and human activity in the Central Apennine Mountains, Italy. Journal of Quaternary Science, 28, 71-82.
The Antarctic Peninsula Ice Sheet is the most northerly of the Antarctic ice sheets and the most vulnerable to climate warming. In light of recent instrumental records of warming along the Antarctic Peninsula, there has been much debate about what has influenced rising temperatures along the west Antarctica Peninsula (WAP) during the Holocene, with terrestrial and oceanic proxies often suggesting different, sometimes opposing, mean conditions. Here, we present a Holocene glacial (terrestrial ice) melt water record derived from marine δ18Odiatom from Palmer Deep, west Antarctic Peninsula. Our results provide a unique opportunity to assess atmospheric versus oceanic influence on melting along the WAP. We demonstrate that since approximately 5.0 ka the increasing occurrence of La NiÃ±a, as recorded in the lower latitude Pacific, and increasing summer insolation at 60ºS have had a stronger influence on glacial melt water inflow to the WAP margin than oceanic processes driven by the southern westerly winds.
Pike, J., Swann, G.A.E., Leng, M.J., Snelling, A. 2013. Glacial discharge along the west Antarctic Penninsula during the Holocene. Nature Geoscience. Online.
The late Mesoproterozoic Sveconorwegian orogen in southwest Baltica is traditionally interpreted as the eastward continuation of the Grenville orogen in Canada, resulting from collision with Amazonia, forming a central part in the assembly of the Rodinia supercontinent. We challenge this conventional view based on results from recent work in southwest Norway demonstrating voluminous subduction–related magmatism in the period 1050–1020 Ma, followed by geographically restricted high–T/medium–P metamorphism between 1035 and 970 Ma, succeeded by ferroan magmatism over large parts of south Norway in the period 990–920 Ma.
This magmatic and metamorphic evolution may be better understood as reflecting a long–lived accretionary margin, undergoing periodic compression and extension, than continent–continent collision. This study has implications for Grenville–Sveconorwegian correlations, comparisons with modern continental margins, Rodinia reconstructions and how we recognize geodynamic settings in ancient orogens.
Slagstad, T., Roberts, N.M.W., Marker, M., Røhr, T., Schiellerup, H. 2013. A Non-Collisional, Accretionary Sveconorwegian Orogen. Terra Nova 25, 30-37.
Precambrian Research – January 2013
We present a study of the position, nature and geochronology of the eastern margin of the Tanzania Craton near Mpwapwa, which yields new constraints on Archaean to Neoproterozoic orogenesis of central Tanzania. The eastern margin of the Tanzania Craton is a ca. 1960 Ma top-to-the-NW ductile thrust zone. Orthogneisses of the eastern part of craton were dated by U–Pb zircon at ca. 2.7 Ga. High grade paragneisses to the east (Mpwapwa Group) are also Archaean (>ca. 2.6 Ga) and thus do not belong to the Usagaran belt, but to the “Western Granulite” of the East African Orogen. Charnockites in the south have been dated at 2701 ±
21 Ma and point to a third Archaean assemblage. A post-Usagaran granite dated at 1873 ± 31 Ma shows Neoproterozoic metamorphic zircon rims that grew during the East African orogenic event.
A sliver of southern tonalitic orthogneiss, entrained in the craton margin shear zone, is an igneous rock of probable early Palaeoproterozoic or Archaean age (>ca. 2300 Ma) with a strong metamorphic overprint at ca. 1960 Ma (zircon), confirmed by a metamorphic titanite age of ca. 1990 Ma, this is believed to date the initial phase of craton-margin shearing and juxtaposition of the Archaean crustal blocks.
Thomas, R.J., Roberts, N.M.W., Jacobs, J., Bushi, A.M., Horstwood, M.S.A., Mruma, A. 2013. Structural and geochronological constraints on the evolution of the eastern margin of the Tanzania Craton in the Mpwapwa area, central Tanzania. Precambrian Research 224, 671-689.
August 2014 - Can isotopes help define the Anthropocene? By Dr Jonathan Dean
The Anthropocene is a term that is increasingly being used to refer to the current interval in geological time in which humans have become a dominant force of global environmental change. It was coined by Prof Eugene Stoermer, a biologist, in the 1980s and popularised in the early 2000s by Prof Paul Crutzen, an atmospheric chemist…
July 2014 - Using carbon isotopes to study Lake Baikal... by Sarah Roberts
Today we're very pleased to share a guest post from Sarah Roberts, a Postgraduate Researcher at the School of Geography, University of Nottingham. Here she introduces her exciting collaborative work, to investigate changes in nutrient fluxes at Lake Baikal, Siberia, with the Baikal research team; Dr. George Swann, Prof. Anson Mackay, Dr. Suzanne McGowan and Dr. Virginia Panizzo (BGS Visiting Research Associates) and BGS staff...
July 2014 - The Ohrid Sequel: Cheshire Mere... by Jack Lacey
Jack Lacey is a familiar face to the blog. Over the last 16 months he's taken us along on amazing fieldwork adventures to Lake Ohrid, drilling through 3 million years of Earth's history and looking for the impacts of volcanic super eruptions using lake sediment records. But this was just phase 1 of his PhD research. Here Jack tells us what's in store for Phase 2 as he works within the Centre for Environmental Geochemistry, a collaboration between the University of Nottingham and the BGS...
A new research project has begun to examine the history of chickens, involving archaeological records to investigate the history of the world’s most widely established livestock species, originally descended from the wild jungle fowl of South East Asia. The project, entitled "Cultural and Scientific Perceptions of Human-Chicken Interactions", was made possible with the help of a £1.94 million grant from the AHRC under the Science In Culture Awards Large Grants call. Researchers from Bournemouth University, as well as the Universities of Durham, Nottingham, Leicester, Roehampton and York, will be examining when and how rapidly domesticated chickens
spread across Europe and the history of their exploitation for meat and eggs. Research methods will include stable isotope analysis at the BGS Stable Isotope Facility, in collaboration with the University of Nottingham within The Centre for Environmental Geochemistry...
May 2014 - The mass exodus of geoscientists to Vienna... by Prof Melanie Leng
Every year around this time a European Geosciences Union (EGU) is held in Vienna, Austria. The weeklong conference brings together geoscientists from all over the world to discuss their latest findings in earth, planetary and space sciences...
April 2014 - Oxygen isotopes and lakes by Prof Melanie Leng and Dr Jonathan Dean
Lakes occur across the globe and are sensitive to climatic change. Analysing the sediments that have accumulated at the bottom of lakes over time can help us to reconstruct past environmental change...
March 2014 - Geoblog on the new mass spectrometer at the BGS
The British Geological Survey (BGS) took delivery of a new mass spectrometer this month. This instrument, acquired with joint funding from the University of Nottingham, will provide the UK’s environmental geoscience community access to one of the most precise research equipment for use in environmental research. Melanie Leng tells us more...
February 2014 - Ancient Climate Secrets by Jonathan Dean
Jonathan Dean started working as a Stable Isotope Apprentice in NIGL this January after he finished his PhD research at the University of Nottingham. Here he tells us a little bit about his research into how lake sediments are revealing secrets of past climates...
January 2014 - Using “proxy” data to tell us about past climate change by Melanie Leng
One of the highlights of 2013 was publication of our research, in collaboration with the British Antarctic Survey and various UK Universities, on past climates along the Antarctic Peninsula, here Professor Melanie Leng tells us how climate change from 11,000 years ago to the last few decades has affected the Antarctic from 'proxy data'…
November 2013 - The Thrill to Drill (over the next 10 years) by Prof Melanie Leng
Last week the International Continental scientific Drilling Program (ICDP) Science Conference was held in the historic Telegrafenberg in Potsdam, Germany. The aim of the conference was to debate and map ICDP’s way forward over the next 5 – 10 years and develop a science plan for continental deep drilling. Here Melanie Leng gives us a brief overview:
September 2013 – The TW:eed core arrives at the National Core Repository in Keyworth..... by Dr Andrea Snelling
Andrea Snelling has just joined the TW:eed team. Her speciality within TW:eed is to use stable isotope composition of the rocks to help interpret palaeoenvironment around the time of tetrapod evolution...
September 2013 – QRA Post Graduate Symposium blog..... by Mel Leng
In the last week of August the Quaternary Research Association held their annual post graduate symposium. The symposium, held at the University of Southampton, was a meeting arranged by- and for only PhD and MSc students studying climate and environmental change over the last 2.6 million years...
July 2013 – BGS GeoBlog - The International Continental scientific Drilling Program (ICDP) funding process – part 2..... by Melanie Leng
The UK became a member of the ICDP in 2012, this enables us (UK geoscientists) to apply for funding for deep scientific drilling projects, as well as having representatives on the three committees that oversee ICDP funding allocations. Melanie Leng sits on the Executive Committee and here explains her first experience of the panel which met in Sendai, Japan, last week...
June 2013 – BGS GeoBlog - Flights and Funding for ICDP - part 1..... by Melanie Leng
9 hours ago I touched down in Tokyo, Japan. I'm on my way to Sendai to represent the UK geoscience community on the ICDP Executive Committee. Here I fill you in on what I have learned so far about the ICDP funding process...
June 2013 – BGS GeoBlog - Spot the Geologist - the start of my PhD..... by Leah Nolan
Leah starts her PhD research, in Geology at Leicester University and in association with the BGS, in October. Here she describes her first field visit to the picturesque Lathkill Dale in the Peak District where famous Lower Carboniferous limestones out crop...
April 2013 – BGS GeoBlog - Final steps of our South Georgia expedition by Mel Leng
I am back on board the Polarstern after an amazing few weeks on South Georgia. Today we visited the old whaling station of Grytviken next to the British Antarctic Survey’s research base at King Edward Point…
April 2013 – BGS GeoBlog - Sightseeing in South Georgia by Melanie Leng
II have finally arrived on the Falkland Islands after an epic field trip to South Georgia. We have been dropped off by the Polarstern and this is the final step before we leave for the UK in a few days…
April 2013 – BGS GeoBlog - The End of the South Georgia expedition
A BGS blog by Melanie Leng: We are almost at the end of our expedition to South Georgia. Worsening weather around the South Sandwich Islands has meant that the Polarstern has had to abandon some of it’s seabed surveying…
March 2013 – BGS GeoBlog - Preparing for an expedition to South Georgia
A BGS blog by Melanie Leng: In a few days I'll be following in the footsteps of James Cook (1775) and Ernest Shackleton (1916) and embarking on an adventure in the South Atlantic. I'm bound for fieldwork on South Georgia, a remote and inhospitable island with no permanent inhabitants, approximately 200km SE of the Falkland Islands…
March 2013 – BGS GeoBlog - Drilling through 3 million years of Earth’s history in the Mediterranean by PhD student Jack Lacey
Meet Jack….a PhD student from University of Leicester looking into 3 million years of the Earths history. His BGS/NIGL sponsored PhD is part of a multi-million dollar campaign to investigate the evolution and climate of Lake Ohrid through the drilling and recovery of a 750 meter-long sediment core. Amazingly that's the length of 90 double decker buses or 37 cricket pitches!! Here Jack introduces the project and explains what he'll be up to over the next few months (and years)…
March 2013 – BGS GeoBlog - Can clam shells explain the demise of a civilisation?
A BGS blog by Melanie Leng: Clam shells used for food, jewellery and in the wall covering of shelters found at the world famous Çatalhöyük UNESCO archaeological site in Central Turkey between 8-9,000 years ago give a unique insight into the demise of a short lived civilisation…
WalesOnline (Western Mail) – Evidence of continued climate change for thousands of years – January 2013
As Wales continues to endure freezing temperatures after a year of extreme weather a study by a Welsh university has revealed continued patterns of climate change over the past 12,000 years… Read more: Wales Online
January 2013 – BGS GeoBlog - Tiny fossils reveal evidence for climate change and melting of Antarctica
A BGS blog by Melanie Leng: The Antarctic Peninsula Ice Sheet is one of the most rapidly warming areas of the planet. This is causing concern as it contains enough water to raise global sea levels by 5m. By analysing the chemistry of microscopic marine algae that lived in the ocean surrounding Antarctica, scientists have created a record of the amount of melting of the ice sheet that stretches back 12,000 years. This window through time has already unlocked hidden patterns in our past climate…
February 2014: International Drilling Panel for Professor Melanie Leng
Melanie Leng has been nominated to represent the International Continental scientific Drilling Program (ICDP) on the International Ocean Discovery Program (IODP)/European Consortium for Ocean Research Drilling (ECORD) outreach task force.
Working together, the ICDP and IODP have organised an outreach task force to facilitate joint outreach activities that might include conference booths/sessions and town hall meetings etc., which develops on from the combined 'Scientific Drilling' journal.
The task force will have a remit to develop new outreach tools and strategies for the long-term. Please contact Melanie if you are interested drilling outreach.
Follow ICDP on Twitter: @icdpDrilling and Mel: @MelJLeng
August 2013: Top spot for Quaternary Science Reviews article on isotopes in climate change research
A review article on the use of isotope geochemistry in lake sediments as a means of understanding past climates remains one of the top down loaded articles in, the environmental change journal, Quaternary Science Reviews. The paper by Professor Melanie Leng (BGS/University of Leicester) and Professor Jim Marshall (University of Liverpool) has been consistently one of the journal’s most down loaded articles since its publication in 2004. As a reward for it’s popularity the journal have made the article open access till 31st October 2013. The paper has been cited over 350 times (Google Scholar).
July 2013: NERC £1.2 m grant: Climatic change and human evolution
The Natural Environment Research Council (NERC) has approved a grant of £1.2 m to a UK team including researchers at the British Geological Survey (BGS) to investigate the influence of past climatic changes on human evolution in Africa.
In November 2013, working with partners from Germany, the US, and Ethiopia, the team will drill a 400 m-deep sediment core from Chew Bahir, an ancient lake basin in south Ethiopia, close to some of the world's most famous human fossil sites.
Over the next three years, the cores will yield a high-resolution record of changes in rainfall, temperature and vegetation spanning at least the last 500 000 years, a period that covers the evolution of our species, Homo sapiens, and dispersal of our distant ancestors from Africa into Asia and Europe.
Until now, there have been no such long environmental records from the African centre of human origins, so ideas about how climatic change may have influenced the emergence and dispersal of modern humans have remained largely speculative. By placing the fossil and archaeological data against a detailed record of regional climatic variation, and by modelling the likely effects of changing local environments on ancient human populations, the project will develop the first rigorous tests of hypotheses about how climate drove the genetic and cultural evolution of our species, and our eventual spread to every part of the globe.
The Chew Bahir project is part of the Hominin Sites and Paleolakes Drilling Project, a multi-national research effort to obtain core records of climatic change from five key palaeoanthropological sites in east Africa, covering the last four million years of human evolution.
The UK part of the project is headed by Professor Henry Lamb (Aberystwyth University) who leads a strong research team, including Professor Melanie Leng (BGS/University of Leicester) as well as scientists from Bangor, Liverpool, Newcastle, Oxford, and St Andrews universities.
Cores, from Kenya and Chew Bahir will be analysed initially at the US National Lake Core laboratories (LacCore) at the University of Minnesota, Minneapolis. Samples for dating, microfossil, and geochemical/isotope analysis will then be studied at the team's specialist laboratories (including the BGS stable isotope laboratory) in the UK and Cologne, Germany.
A one day workshop (keynote speakers plus posters) on issues around the nitrogen isotope cycle and the Anthropocene.
There are several types of temporal record (ice cores, sediments, tree rings) which show a reduction in 15N/14N ratios during the 'Anthropocene', a period in which there has been a substantial increase in the amount of reactive nitrogen in the earth's nitrogen cycle. These changes are thought to be mainly due to the industrial synthesis and application of fertilizers, other changes in farming, and the combustion of fossil fuels. However, there does not seem to be any general agreement on the mechanism/s which cause this change in 15N/14N ratios, or indeed whether the changes in different records are related.
The workshop will therefore aim to promote discussion around: 15N depletion in organic matter in recent lake sediments; the lag between 15N in recent ice cores and lake sediments; recent 15N changes in modern plants/trees and soils; changing sources of N in glaciers and ice cores; and on how changes in source inputs to the atmosphere, and/or changes in its chemistry processes during the past few hundred years might have resulted in a decrease in 15N/14N of deposited N?
Key note presentations:
Jan Zalasiewicz (University of Leicester): Stratigraphy of the Anthropocene: an overview.
Jan Kaiser (University of East Anglia): Isotopic evidence of sources and chemical processing of nitrogen in the atmosphere.
Eric Wolff (University of Cambridge): Ice core signals of a changing nitrogen cycle.
Tim Heaton (British Geological Survey): Sediment, soil and plant records of changes in 15N/14N ratios during the Anthropocene.
The meeting will be held at the British Geological Survey in Keyworth on Wednesday 29th October 2014. Contact Melanie Leng for more information or register an interest in attending.