Jane Evans appointed Special Associate Professor - June 2010
Congratulations to Jane Evans who has been appointed Special Associate Professor in the School of Humanities at the University of Nottingham. The appointment is on the basis of Jane being a distinguished practitioner in the field of isotopes in archaeological science and is aimed at strengthening links between BGS and the university.
Dr Nick Roberts: new appointment - June 2010
Nick Roberts has joined NIGL as a research support scientist, working primarily in the plasma ionisation mass spectrometry (PIMS) facility. Nick will be involved in improving current techniques in U-Th-Pb geochronology and Lu-Hf isotope analysis, and will also be involved in developing methodologies on the single-collector mass-spectrometer, including Uranium-series dating of carbonates. Nick has recently finished a PhD at the University of Leicester, of which a significant component involved LA-ICP-MS and TIMS analyses at NIGL.
Dr Nicola Atkinson: new appointment January 2010
Nicola Atkinson has joined NIGL as an Isotope scientist within the geochronology group, where she will provide analytical support for uranium-daughter isotope research undertaken in the geochronology group. Nicola will be responsible for the low-Pb blank chemistry facility used for the analysis of zircons and other U-bearing accessory phases, and will be involved with chemical purification techniques, mass spectrometric analyses of blanks and samples by TIMS and ICP-MS.
Adam Young: new appointment - January 2010
Welcome to Dr Adam Young who recently started a short term training position within NIGL to work on improvement of carbonate isotope techniques and mass spectrometry. Adam will also be continuing his research on environmental change archives from the Badain Jaran Desert, north-west China. In particular he is interested in the modern hydrology and recent lake sediment archives using isotope techniques.
Dr Adam Martin: new PDRA October 2009
Adam Martin has recently joined NIGL as a Post-Doctoral researcher. The post is part of an international multi-disciplinary project, FAR-DEEP (Fennoscandia Arctic Russia - Drilling Early Earth Project). FAR-DEEP is an internationally supported (ICDP, NGU and various national research councils) project with one overarching goal: to develop a comprehensive, self-consistent model explaining the transformation of Earth from an anoxic to oxic planet and the subsequent transition to an aerobic Earth System. NIGL will be responsible for the integration of high-precision geochronology into the models developed from the FAR-DEEP research, and will work closely with other UK researchers from the Scottish Universities Environmental Research Centre and University of St-Andrews, using mainly high precision TIMS and LA-ICP-MS techniques. His research background is in the petrology and chemistry of the Antarctic lithosphere; U-Pb, Ar-Ar, and K-Ar chronology; and low-sulphidation epithermal gold deposits.
Dr Laura Bracciali: new PRDA - September 2009
Laura Bracciali has recently joined NIGL as a Post Doctoral Research Associate investigating the evolving composition of the Brahmaputra River sediments through Neogene time by means of a multi-technique provenance study, with the aim of testing competing hypotheses of drainage evolution and erosion-tectonic coupling. Her research background deals with aspects of igneous and sedimentary petrology, including field work, petrography, trace element/isotope geochemistry, as applied to understanding problems of orogenic evolution and palaeotectonic reconstructions.
Her appointment is associated with a three year NERC standard grant awarded to Randy Parrish.
NERC's Peer Review College - July 2009
Congratulations to Randy Parrish who has been nominated to sit on the NERC Peer Review College from July 2009 to July 2012.
Dr Andrea Snelling: new appointment June 2009
Andrea Snelling recently joined NIGL to work on the δ18O record of diatoms from Antarctica, investigating the evolution of seasonality during the Late Quaternary. Andrea will be preparing and cleaning samples as well as working on novel techniques such as micromanipulation for the abstraction of season specific diatom species for stable isotope analysis. Her appointment is associated with NERC Standard grant award: Diatom Silica Oxygen Isotope Records from the Late Quaternary Antarctic Margin - led by Melanie Leng and George Swann at NIGL and Jenny Pike at Cardiff.
Silicon Editorial Board appointment for Prof Melanie Leng February 2009
Congratulations to Melanie Leng on her appointment to the Editorial Advisory Board of Silicon. The appointment is to run for two years. Silicon is an international, interdisciplinary journal solely devoted to the most important element of the 21st Century. Silicons coverage is unique in presenting all areas of silicon research and development across all disciplines. Silicon is a quarterly journal publishing the very latest cutting edge research in materials chemistry, materials physics, materials biology, materials engineering and environmental science.
Professor Sarah Metcalfe awarded Visiting Research Associate November 2008
Sarah Metcalfe (School of Geography, Nottingham University) has been awarded a VRA at NIGL/BGS. Sarah will be spending her time at NIGL working with Melanie Leng on improved understanding of controls on isotopic composition of Mexican lake systems to develop their use to reconstruct changes in the Mexican monsoon. This will also be tied in with their mutual interest in comparing the tropical Americas with the near East and the balance between mid-latitude and tropical climate systems over time.
Congratulations to Dr George Swann on gaining a NERC Postdoctoral Fellowship - May 2008
George Swann has gained a NERC Postdoctoral Fellowship based at NIGL for 3 years from September 2008. George will be working on investigating
changes in the biological pump of the North Pacific Ocean over the last glacial cycle (MIS 5e to MIS 1) and assess the extent to which these variations
may have modulated past concentrations of atmospheric CO2. This will be primarily accomplished by establishing a high-resolution record
of diatom stable isotopes (δ13C, δ18O, δ30Si) in a series of sediment cores spread across the
North Pacific Ocean. Results from this will enable past spatial and temporal changes in surface water export production, nutrient utilisation and
the stability of the water column to be reconstructed.
In turn, this will allow the role of the North Pacific Ocean in ventilating/drawing-down CO2 into/out of the atmosphere to be established
over both long, glacial-interglacial, and shorter, millennial, timescales.
Melanie Leng awarded Visiting Professor - February 2008
Congratulations to Prof Melanie Leng who has been awarded the position of Visiting Professor in the Department of Geology, University of Leicester.
The appointment is to enhance Leicester-NIGL collaboration in the field of environmental reconstruction using stable isotopes.
Joseph will be based at NIGL while undertaking a joint BGS/Bradford University PhD to study Systematic biosphere mapping of 87Sr/86Sr
ratios across major lithological boundaries in southern England.
Congratulations to Professor Parrish
Randy Parrish has accepted the position of European Editor of Precambrian Research from September 2007: More information
NERC's Peer Review College
Congratulations to Melanie Leng who has been nominated to sit on the NERC Peer Review College from July 2007 to July 2010.
Dr Jane Evans awarded Honorary Fellow
Congratulations to Jane Evans who has been awarded an Honorary Fellowship at the Department of Archaeology, Nottingham University.
May 2010. Congratulations to Maite Hernandez (Bristol/Southampton) who recently defended her PhD entitled: productivity variations around a naturally iron fertilised region of the ocean: The Crozet Plateau, Southern ocean.
An enhancement of the biological pump due to increased Fe input to oceanic HNLC regions has been proposed as a major control on the global carbon cycle during glacial periods. However, identification of Fe fertilization events through the geological past is hampered by (a) the lack of characterization of these events in the modern ocean and (b) the use of single proxies in a given region, which produces equivocal results. A multi-proxy approach provides a way to successfully characterise the response of marine productivity in the modern ocean and further assess productivity variations through geological time. In this thesis, a multi-proxy approach (using biomarkers, bulk and specific compound δ13C values, bulk δ15N values, biogenic silica, Baxs and Babio, carbonate and lithogenic content) is applied to characterise productivity in a naturally fertilised area of the Southern Ocean, the Crozet Plateau, and is compared with a nearby HNLC area of the Southern Ocean.
Maite was supervised by Rich Pancost (Bristol), Rachel Mills (Southampton), and Melanie Leng (NIGL)
April 2010. Congratulations to Charlotte Cook (Exeter University) who has defended her PhD entitled: Late Pleistocene - Early Holocene glacial dynamics, Asian palaeomonsoon variability and landscape change at Lake Shudu, Yunnan Province, southwestern China.
A lack of well-distributed, high-resolution records of Late Quaternary Asian palaeomonsoon variability remains an outstanding issue for palaeoclimatologists, and is especially marked in remote regions such as the mountains of southwestern China. Characterising the nature, timing and magnitude of climate variability in southwestern China is essential for understanding the regional climate as a whole, and the potential social, economic and environmental impacts that may result from Asian monsoon system changes. The research presented in this thesis focuses on a high altitude lake sediment record obtained from Lake Shudu, Yunnan Province, China. The lake is located on the southeastern edge of the Tibetan Plateau. The primary aims of this research were to identify and examine key environmental and climatic shifts which occurred in southwestern China during the Late Pleistocene (Dali) - Early Holocene Period; to examine the possible drivers of these changes; and to compare the findings with other regional proxy records in order to better understand climate dynamics in southwestern China.
These aims were chosen in order to test the hypothesis that Late Quaternary millennial to centennial scale climatic and environmental changes in southwestern China were driven by changes in solar insolation and / or glacial climate boundary conditions, characterised by stepwise increases in palaeomonsoon intensity.
Charlotte was supervised by Richard Jones and Chris Caseldine (Exeter), Peter Langdon (Southampton) and Melanie Leng (NIGL).
November 2009. Congratulations to Nicola Atkinson who has defended her PhD thesis entitled: "Heavy metal geochemistry of contaminated fenlands in NW England"
The use of peri-urban fenlands for agriculture using urban waste as manorial treatments is increasingly common worldwide, particularly in developing countries. The risk to human health from the use of these contaminated materials for crop production has been studied using two historically contaminated fenlands in NW England., Chat Moss (west of Manchester) and Halsall Moss (north of Liverpool). Historical research identified the two mossland areas as contaminated with urban wastes, ranging from domestic to industrial wastes. Profiles of contaminated and control sites on Chat Moss and a contaminated site on Halsall Moss were collected, with pH, organic matter content and trace metal content measured. Trace metal content was elevated over subsoil levels in the topsoil of all sites, with arsenic and cadmium concentrations exceeding Soil Guideline Values in the most contaminated site, but all other metals were within guideline limits. Halsall Moss was found to be less contaminated than Chat Moss, due to the mainly organic nature of the waste disposed at Halsall Moss. The mobility and fractionation of the contamination at the most contaminated site on Chat Moss were studied to understand the behaviour of the metals and assess potential risk to ecological or human health. Using sequential extractions, most metals were identified as hosted by organic, Fe/Mn oxide or residual phases. Lability of Pb in the contaminated Chat Moss soil was assessed using 204Pb stable isotope dilution, a new method developed during this project. It was found that 65% of lead was labile. The impact of flooding events on the Chat Moss soils was assessed, and it was found that under mild reducing conditions, large quantities of arsenic, lead, molybdenum and manganese were released to soil solution, and drinking water limits for these metals were violated.
The effect of soil contamination on vegetables grown on Chat Moss was also investigated, EU limits for Cd were exceeded by lettuce and onion, and EU limits for Pb were exceeded by parsley, carrot, radish and onion. Hazard Quotients used to assess the impact of plant contamination in the context of human intake showed that only cadmium and molybdenum were potentially hazardous.
November 2009. Congratulations to Carys Bennett (Leicester-NIGL-BGS) who successfully defended her PhD thesis on: Lower Carboniferous Ostracods and Isotopes of the Midland Valley, Scotland: testing for the ecological shift into non-marine environments
Ostracods are a diverse group of arthropod crustaceans with a geological record from the Ordovician. Their radiation from marine to non-marine environments is a key step in the evolution of the group. The nature and chronology of this transition is examined, and proxies for non-marine environments determined. The Mississippian of the Midland Valley of Scotland contains a wide range of marine to non-marine ostracods, macrofauna and sediments that make it an ideal study area. This study documents the evidence for early Mississippian freshwater ostracods, 20 million years earlier that the previous records. Twenty five ostracod species are described, four of which are new species. Macrofossils are used to interpret the environmental tolerance of the ostracods. Key brackish to freshwater ostracods are species of Carbonita, Geisina arcuata, and Paraparchites circularis n. sp. Algal palynomorphs associated with the ostracods are interpreted as freshwater in origin. Botryococcus sp., three new types of algal palynomorph and arthropod fragments are identified.
A protocol for the examination of diagenetic alteration of ostracods is proposed, which is essential prior to any isotope analysis. Diagenetically altered ostracods may be mistaken as pristine specimens, without a study of the carapace ultrastructure. The ostracods have undergone seven stages of diagenesis. The carbon and oxygen stable isotope data from the ostracods reflect these stages of diagenesis. This protocol can be applied to other microfossil and macrofossil groups.
October 2009. Congratulations to Christina Jonsson (Stockholm-NIGL) who gained her PhD on "Holocene climate and atmospheric circulation changes in northern Fennoscandia: Interpretations from lacustrine oxygen isotope records".
Christina's thesis involved investigation of how variations in the oxygen isotopic composition of lake waters in northern Fennoscandia are recorded in lake sediment archives, especially diatoms, and how these variations can be used to infer past changes in climate and atmospheric circulation. She showed a long-term Holocene decreasing δ18O which was likely forced by a shift from strong zonal westerly airflow in the early Holocene to a more meridional flow pattern. The large δ18Olakew depletion recorded in the δ18O records around ca. 600 cal yr BP (AD 1350) may be due to a shift to more intense meridional airflow over northern Fennoscandia resulting in an increasing proportion of winter precipitation from the north or southeast. This climate shift probably marks the onset of the so-called Little Ice Age in this region.
Christina was supervised by Ninis Rosqvist in Stockholm University and Melanie Leng at NIGL.
August 2009. Congratulation to Adam Young (UCL-NIGL) who successfully defended his PhD: Lake-sediment records of recent climate variability in north-west China's drylands.
Adam's research looked at group of lakes in the Badain Jaran Desert, in north-west China. Despite the arid nature of the region, there are over 100 permanent groundwater fed lakes in the desert, which are situation between sand dunes that are <500 m tall. The landward limit of precipitation associated with the East Asian summer monsoon lies across the desert and the aim of the PhD was to reconstruct variability of the monsoon from lake sediment records. To achieve this goal, the modern hydrological setting of the lakes needed to be fully understood. Geochemical and isotopic data of lake water and groundwater data showed that the lakes can be divided into a northern and a south-eastern suite that are geochemically, isotopically and physically distinct. They are all evaporatively enriched, but in the south-eastern suite this is controlled by individual basin morphology, whereas the lakes in the northern suite have all reached their maximum heavy isotope enrichment value. An isotope mass balance model showed that δ18O values are primarily controlled by relative humidity, and secondarily by δ18O values of input water. Four short sediment cores from the south-eastern suite were dated using the AD 1963 137Cs peak.
Comparisons of multiproxy analysis (including δ13C and δ18O values of endogenic and biogenic calcite; C/N ratios and δ13C values of organic carbon; and Sr/Ca and Mg/Ca of biogenic calcite) of these cores to regional palaeoclimate records shows that evaporative enrichment has been caused by changes in humidity. The records also suggest that periods of increased monsoonal activity correspond to a decrease in effective moisture across the region. Since 1970 the aridity trend that the lakes have shown is probably caused by anthropogenic increases in global temperature, indicating that further increases may cause the lakes to dry out completely.
July 2009. Congratulations to Keely Mills (Loughborough University) who has defended her PhD thesis entitled: Ugandan Crater Lakes: Limnology, Palaeolimnology and Palaeoenvironmental history.
This thesis presents the results of contemporary limnological and palaeolimnological investigations of a series of crater lakes in order to reconstruct the palaeoenvironmental history of western Uganda, East Africa. The research examines questions of spatial and temporal heterogeneity of climate changes in the context of growing human impacts on the landscape over the last millennium. Sediment records from two lakes, Yamogusingiri and Kyasanduka within the Queen Elizabeth National Park were investigated to look at the long term records of climate and environmental change (spanning the last c. 1000 years). High-resolution (sub-decadal), multiproxy analyses of lake sediment cores based on diatoms, bulk geochemistry (C/N and δ13C) and sedimentary variables provide independent lines of evidence that allow the reconstruction of past climate and environmental changes.
This multiproxy approach provides a powerful means to reconstruct past environments, whilst the multi-lake approach assists in the identification and separation of local (e.g. catchment-scale modifications and groundwater influences) and regional effects (e.g. climatic changes).
June 2009. Congratulations to Andrea Snelling (Leicester-BGS) who successfully defender her PhD thesis: Characterisation of stratigraphy and palaeoceanography using graptolites: exploring new concepts in the Aeronian (Silurian) of Wales, Scotland and Northern Ireland.
Her research compared the graptolite faunas from the three study areas and investigated new techniques for graptolite biostratigraphy including X-ray imaging. Species that had not been recovered using conventional collecting techniques were revealed and the technique also identified concentrations of graptolite fossils within anoxic hemipelagic sequences. A schema of facies types was constructed for anoxic hemipelagite mud-rocks on a sub-millimetre scale to identify if the concentrations of graptolite fossils were linked to particular facies types. This study also investigated the use of graptolite periderm (skin) for δ13C analysis.
April 2009. Congratulations to Alex Dickson (UCL-NIGL) who successfully defended his thesis: Palaeoceanographic variability in the South East Atlantic Ocean during periods of low orbital eccentricity
The Marine Isotope Stage (MIS) 11 interglacial has been considered to be analogous to the Holocene because of a similarity in the conditions of orbital forcing (low eccentricty and precession), but the role of climatic feedback processes linking orbital drivers to climate signatures is not well understood. Alex's thesis examines palaeoceanographic sediment records from the South East Atlantic Ocean covering the last 50,000 years and the period encompassing MIS-11 (335-475 ka) to better understand how different facets of the climate systems were linked together in these two periods of low orbital eccentricity.
March 2009. Congratulations to Tanya Knowles (NHM, Reading) who successfully defended her PhD thesis: Fossil cheilostome Bryozoa of the mid-Pliocene North Atlantic and the inference of environmental regimes.
This research was based on bryozoans from the mid-Pliocene warm period, a time characterised by global warmth and high sea levels. The Mean Annual Range of Temperature (MART) experienced by a bryozoan colony can be estimated utilising the inverse relationship between zooid size in cheilostome bryozoans and water temperature at the time of budding as well as from oxygen isotope analysis of the calcareous skeleton. In this study both techniques were applied to Pliocene bryozoan material from the UK, US Coastal Plain, Florida and the Isthmus of Panama. The data from a range of latitudes provide information about shelf sea temperatures, and were found to be consistent with outputs from mid-Pliocene scenarios generated by numerical models of climate.
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)
Quaternary Science Reviews - August 2010
This paper reviews our current understanding of karst drip-water hydrology, emphasizing the extent of non-linear and non-stationary process dynamics that render stalagmite palaeoclimate reconstructions using a statistical pseudo-proxy approach difficult to implement.
Bradley, C., Baker, A., Jex, C.N., Leng, M.J. 2010. Hydrological uncertainties in the modelling of cave drip-water δ18O and the implications for stalagmite palaeoclimate reconstructions. Quaternary Science Reviews, 29, 2201-2214.
A sub-centennial-resolution record of lacustrine carbonate oxygen isotopes from the closed-basin Lake Qinghai on the NE Tibetan Plateau shows pronounced variability over the past 1500 years. It is proposed that the Little Ice Age signal in Lake Qinghai resulted from a reduction in evaporation caused by colder air temperatures, coupled with a decrease in oxygen isotope composition of input waters as a result of an increase in the relative importance of westerly derived precipitation.
Henderson, A.C.G., Holmes, J.A., Leng, M.J. 2010. Late Holocene isotope hydrology of lake Qinghai, NE Tibetan Plateau: effective moisture variability and atmospheric circulation changes. Quaternary Science Reviews, 29, 2215-2223.
Two methods for calculating sedimentary Biogenic Silica (BSi) concentrations are assessed using late glacial/Holocene aged material from Lake Baikal, Russia. Results show that the Si-only and Si/Al wet-alkaline methods produce comparable data when levels of non-BSi digestion are low to moderate making both techniques suitable for use in palaeoenvironmental research.
Swann, G.E.A. 2010. A comparison of the Si/Al and Si/time wet-alkaline digestion methods for measurement of biogenic silica in lake sediments. Journal of Paleolimnology, 44, 375-385.
The sedimentary record from the paleolake at Les Echets in eastern France allowed a reconstruction of the lacustrine response to several abrupt climate shifts during the last glacial period referred to as Dansgaard-Oeschger (DO) cycles.
Ampel, L., Wohlfarth, B., Risberg, J., Veres, D., Leng, M.J., Kaislahti Tillman, P. 2010. Diatom assemblage dynamics during abrupt climate change: the response of lacustrine diatoms to Dansgaard-Oeschger cycles during the last glacial period. Journal of Palaeolimnology, 44, 397-404.
The Lateglacial-early Holocene transition from the Lago Chungará record in northern Chilean Altiplano is made up of laminated sediments composed of light and dark pluriannual couplets of diatomaceous ooze. Diatom oxygen isotope composition of diatom laminae suggest that during the Lateglacial-early Holocene transition there occurred a series of decadal-to-centennial wet–dry oscillations. The spectral analyses of the δ18Odiatom values suggest that these events could be triggered by both El Niño-Southern Oscillation (ENSO) and solar activity.
Hernández, A., Giralt, S., Bao, R., Sáez, A., Leng, M.J., Barker, P.A. 2010. ENSO and solar activity signals from oxygen isotopes in diatom silica during Lateglacial-Holocene transition in Central Andes (18°S). Journal of Paleolimnology, 44, 413-429.
Savo volcano, a recently eruptive (1830–1840 AD) trachyte-dominated island arc stratovolcano in the Solomon Islands, has an unusual hydrothermal system. Hot springs (c. 100 °C) near to the volcanic crater discharge alkaline waters instead of the more commonly recognised acidic fluids. Strontium, oxygen and hydrogen isotopes confirm water–rock reaction and mixing with groundwater as primary controls on the composition of the alkaline sulphate springs. The highly unusual dilute chemistry of all discharges at Savo is a consequence of climatic control (high regional rainfall), and results from open system mixing at depth between hydrothermal and meteoric waters.
D.J. Smith, G.R.T. Jenkin, J. Naden, A.J. Boyce, M.G. Petterson, T. Toba, W.G. Darling, H. Taylor, I.L. Millar. 2010. Anomalous alkaline sulphate fluids produced in a magmatic hydrothermal system – Savo, Solomon Islands. Chemical Geology, 275, 35-49.
The chemical and isotopic composition of some Cenozoic volcanic rocks from Jamaica is very similar to that of the oldest surviving continental crust on Earth. We know that the Jamaican rocks were generated by underthrusting (or subduction) and partial melting of oceanic plateau crust beneath Jamaica. This setting is analogous to proposed plate tectonic processes in the early Archaean where hot, thick, and more buoyant oceanic crust underthrusts adjacent plates. The new data support the existence of plate tectonics and primitive subduction zones more than 3,500 million years ago.
Hastie,A.R., Kerr, A.C., McDonald, I., Mitchell, S.F., Pearce, J.A., Wolstencroft, M. and Millar, I.L. 2010. Do Cenozoic analogues support a plate tectonic origin for Earth's earliest continental crust? Geology, 38, p495-498.
Stalagmite records of oxygen (δ18O) isotopes, sampled at sub-annual resolution by micro-mill techniques are correlated with climate parameters over the instrumental period (1961 to 2005 AD). The strongest correlations were found between δ18O and total amount of late autumn–winter precipitation (October to January) smoothed by 6 yr, with marginally weaker correlations between the total amount of late autumn–spring precipitation (ONDJF and ONDJFMA) smoothed over the same time period.
Jex, C., Baker, A., Fairchild, I.J., Eastwood, W., Leng, M., Sloane, H., Thomas, L., Bekaroglu, E. 2010. Calibration of speleothem δ18O with instrumental climatic records from Turkey. Global and Planetary Change, 71, 207-217.
Solute yields, laboratory dissolution data and both chemical and isotopic markers of rock weathering reactions are used to characterise the biogeochemistry of glacial meltwaters draining a maritime Antarctic glacier.
Hodson, A, Heaton, T, Langford, H, Newsham, K. 2010. Chemical weathering and solute export by meltwater in a maritime Antarctic glacier basin. Biogeochemistry, 98, 9-27.
Detrital carbonate contamination is one of the principal problems with the integrity of stable isotope data from authigenic lake carbonates. Here we investigate the origin and climatic implications of stable isotope data from carbonate minerals deposited in two Mediterranean lakes: Gölhisar Gölü (SW Turkey) and Lake Pamvotis (NW Greece).
Leng, M.J., Jones, M.D., Frogley, M.F., Eastwood, W.J., Kendrick, C.P., Roberts, C.N. 2010. Detrital carbonate influences on bulk oxygen and carbon isotope composition of lacustrine sediments from the Mediterranean. Global and Planetary Change, 71, 175-182.
Preservation of organic matter in estuarine and coastal areas is an important process in the global carbon cycle. This paper presents bulk δ13C and C/N of organic matter from source to sink in the Pearl River catchment, delta and estuary, and discusses the applicability of δ13C and C/N as indicators for sources of organic matter in deltaic and estuarine sediments.
Yu, F., Zong, Y., Lloyd, J.M., Huang, G., Leng, M.J., Kendrick, C., Lamb, A.L., W.-S Yim, W. 2010. Bulk organic δ13C and C/N as indicators for sediment sources in the Pearl River delta and estuary, southern China. Estuarine, Coastal and Shelf Science, 87, 618-630.
Sediment core MD04-2822 from the Rockall Trough, northeast Atlantic, provides lithological evidence for the expansion of the British Ice Sheet (BIS) onto the Hebridean margin during both the penultimate (Marine Isotope Stage (MIS) 6/Wolstonian/Saalian) and last glaciations (Devensian/Weichselian).
Hibbert, F.D., Austin, W.E., Leng, M.J., Gatliff, R.W. 2010. British ice sheet dynamics inferred from North Atlantic ice-rafted debris records spanning the last 175,000 years. Journal of Quaternary Science, 25, 461-482.
Rapid Communications in Mass Spectrometry - April 2010
Stable isotopes of water have been previously used in catchment studies to separate rain-event water from pre-event groundwater. However, there are a lack of studies at the smaller scale looking at the separation of event water from pre-event water. This is particularly relevant for heavy clay soil systems through which the movement of water is uncertain but is thought to be rainwater-dominated. The data presented here were collected at a rural site in the south-west of England.
Granger, S.J., Bol, R., Meier-Augenstein, W., Leng, M.J., Kemp, H., Heaton, T.H.E., White, S. 2010. The hydrological response of heavy clay grassland soils to rainfall in south-west England using δ2H. Rapid Communications in Mass Spectrometry, 24, 475-482.
Bioclastic flow deposits offshore from the Soufrière Hills volcano on Montserrat in the Lesser Antilles were deposited by the largest volume sediment flows near this active volcano in the last 26 kyr. The volume of these deposits exceeds that of the largest historic volcanic dome collapse in the world, which occurred on Montserrat in 2003. These flows were most probably generated by a large submarine slope failure of the carbonate shelf comprising the south-west flank of Antigua or the east flank of Redonda; adjacent islands that are not volcanically active. The bioclastic flow deposits are relatively coarse-grained and either ungraded or poorly graded, and were deposited by non-cohesive debris flow and high density turbidity currents. The bioclastic deposit often comprises multiple sub-units that cannot be correlated between core sites; some located just 2 km apart. Multiple sub-units in the bioclastic deposit result from either flow reflection, stacking of multiple debris flow lobes, and/or multi-stage collapse of the initial landslide.
This study provides unusually precise constraints on the age of this mass flow event that occurred at ca 14 ka. Few large submarine landslides have been well dated, but the slope failures that have been dated are commonly associated with periods of rapid sea-level change.
Trofimovs, J., Fisher, J.K., Macdonald, H.A., Talling, P.J., Sparks, R.S.J., Hart, M.B., Smart, C.W., Boudon, G., Deplus, C., Komorowski, J, C., Le Friant, A., Moreton, S.G., Leng, M.J. 2010. Evidence for carbonate platform failure during rapid sea-level rise; ca 14 000 year old bioclastic flow deposits in the Lesser Antilles. Sedimentology, 57, 735-759.
Determining the response of sites within the Arctic Circle to long-term climatic change remains an essential pre-requisite for assessing the susceptibility of these regions to future global warming and Arctic amplification. Here we present diatom δ18O and δ30Si data from Lake El'gygytgyn, Russia, and suggest environmental changes that would have impacted across West Beringia from the last glacial maximum to the modern day. In combination with other records, the results raise the potential for climatic teleconnections to exist between the region and sites in the North Atlantic. The presence of a series of 2-3‰ decreases in δ18Odiatom during both the last glacial and the Holocene indicates the sensitivity of the region to perturbations in the global climate system. Evidence of an unusually long Holocene thermal maximum from 11.4-7.6 ka BP is followed by a cooling trend through the remainder of the Holocene in response to changes in solar insolation.
This is culminated over the last 900 years by a significant decrease in δ18Odiatom of 2.3‰, which may be related to a strengthening and easterly shift of the Aleutian Low in addition to possible changes in precipitation seasonality.
Swann, G.E.A., Leng, M.J., Juschus, O., Melles, M., Brigham-Grette, J., Sloane, H.J. 2010. A combined oxygen and silicon diatom isotope record of Late Quaternary change in Lake El'gygytgyn, North East Siberia. Quaternary Science Reviews, 29, 774-789.
Early Holocene warming in Iceland caused rapid glacial ice melt which led to exposed landscapes on which soils developed and floras quickly established. Our records from northern Iceland suggest temperatures were up to 2-2.5°C warmer than present throughout the first two millennia post deglaciation (~10,500 to 8,500) on a background of soil and catchment development before catchment conditions started to stabilise. The warming trend over this period was not uniform however, but punctuated by a series of relatively short lived climatic events. Specifically inwash events are suggested by the δ13Corganic, %TOC and C/N data around 9600 cal BP and 8250 cal BP and are correlated by two independent sites.
There is also evidence from the δ18Ocarbonate and δ13Ccarbonate records which suggests that progressive evaporation of the lakes in the region occurred from ~8200 cal BP, the timing of which accords well with other isotopic records of drier conditions from around the North Atlantic.
Langdon, P.G., Leng, M.J., Holmes, N. and Caseldine, C.J. 2010. Lacustrine evidence of early Holocene environmental change in Northern Iceland: a multiproxy palaeoecology and stable isotope study. The Holocene, 20, 205-214.
We use lake sediment studies from Sweden to illustrate how Holocene-aged oxygen isotope records from lakes located in different hydrological settings can provide information about climate change. In particular changes in precipitation, atmospheric circulation and water balance. We highlight the importance of understanding the present lake hydrology, and the relationship between climate variables and the oxygen isotopic composition of precipitation (δ18Op) and lake waters (δ18Olakewater) for interpretation of the oxygen isotopic record from the sediments (δ18O). Both precipitation reconstructions from northern Sweden and water balance reconstructions from south and central Sweden show that the atmospheric circulation changed from zonal to a more meridional airflow over the Holocene. Superimposed on this Holocene trend are δ18Op minima resembling intervals of the negative phase of the North Atlantic Oscillation (NAO), thus suggesting that the climate of Northern Europe is strongly influenced by atmospheric and oceanic circulation changes over the North Atlantic.
Jonsson, C.E., Andersson, S., Rosqvist, G.C., Leng, M.J. 2010. Reconstructing past atmospheric circulation changes using oxygen isotopes in lake sediments from Sweden. Climate of the Past, 6, 46-62.
This study has produced the first reconstruction of long-term (25,000 years) variation in hydrological balance (rainfall and drought) from near the Equator.
Dirk Verschuren, Jaap S. Sinninghe Damsté, Jasper Moernaut, Iris Kristen, Maarten Blaauw, Maureen Fagot, Gerald H. Haug, Bas van Geel, Marc De Batist, Philip Barker, Mathias Vuille, Daniel Conley, Daniel O. Olago, Isla Milne, Birgit Plessen, Hilde Eggermont, Christian Wolff, Elisabeth Hurrell, Jort Ossebaar, Anna Lyaruu, Johannes van der Plicht, Brian F. Cumming, Achim Brauer, Stephen M. Rucina, James M. Russell, Edward Keppens, Joseph Hus, Raymond S. Bradley, Melanie Leng, Jens Mingram, Norbert R. Nowaczyk.2009. Half-precessional dynamics of monsoon rainfall near the East African equator. Nature, 462,637-641.
With the current concern about global warming there is much interest in understanding conditions which occurred the last time the Earth was experienceing 'greenhouse' conditions – during the Pliocene period about 2 to 5 million years ago. We have therefore been studying patterns of oxygen and carbon isotope compositions, and microgrowth-increment size, in shells of the Queen Scallop Marine in Pliocene rocks of the Coralline Crag formation along the Suffolk coast of the southern North Sea. The data indicate that these shells grew when minimum (winter) seafloor temperatures were similar to present values (typically 6–7 °C), and maximum (summer) seafloor temperatures a few degrees lower than present values (typically 16–17 °C) for the southern North Sea. These results contrast with evidence from other proxies which point to Pliocene winter and summer sea temperatures being higher than at present. We propose the existence of intense thermal stratification in summer, with summer surface temperatures being much higher than those recorded isotopically on the seafloor, and a wider annual range of surface temperature (probably over 14 °C) than at present. The results have important implications for using the Pliocene as a test-bed for numerical models of a greenhouse Earth.
Andrew L.A. Johnson, Jonathan A. Hickson, Annemarie Bird, Bernd R. Schöne, Peter S. Balson, Timothy H.E. Heaton, Mark Williams. 2009. Comparative sclerochronology of modern and mid-Pliocene (c. 3.5 Ma) Aequipecten opercularis (Mollusca, Bivalvia): an insight into past and future climate change in the north-east Atlantic region Palaeogeography, Palaeoclimatology, Palaeoecology, 284, 164–179.
SILICON - November 2009
Silicon isotope geochemistry is a relatively new branch of environmental change research. Here we review the recent developments in the preparation of materials, analytical methods and applications of stable silicon isotope geochemistry in the most common types of biogenic silica currently being analysed. These materials are: diatom, radiolarian and siliceous sponges in lake and ocean sediments and plant phytoliths which are preserved in soils. Despite analyses of Si isotopes being carried out on rocks and minerals since the 1950's and the increasingly widespread use of Si isotopes since the 1990's, to date only a relatively small number of studies have applied Si isotope ratios to environmental change. In lake and ocean sediments the analysis of Si isotope ratios from biogenic materials hold potential to provide an important source of palaeoenvironmental information, especially where carbonates are not preserved.
In plants and soils few studies have used Si isotopes, but important advances have recently been made in the understanding within plant fractionations. These may be useful in the application of Si isotopes in phytoliths to archaeological and palaeoenvironmental contexts.
Leng, M.J., Swann, G.E.A., Hodson, M.J., Tyler, J.J., Patwardhan, S.V., Sloane, H.J. 2009. The potential use of silicon isotope composition of biogenic silica as a proxy for environmental change. SILICON, 1, 65-77.
In this paper we present geological evidence from the Larsemann Hills (Lambert Glacier - Amery Ice Shelf region, East Antarctica) of marine sediments at an altitude of c. 8 m a.s.l., as revealed by diatom, pigment and geochemical proxies in a lake sediment core. The sediments yielded radiocarbon dates between c. 26 650 and 28 750 14C yr BP (31 366-33 228 cal yr BP). This information can be used to constrain relative sea level adjacent to the Lambert Glacier at the end of Marine Isotope Stage 3. These data are compared with the age and altitude of Marine Isotope Stage 3 marine deposits elsewhere in East Antarctica and discussed with reference to late Quaternary ice sheet history and eustatic sea-level change.
Hodgson, D.A., Verleyen, E., Vyverman, W., Sabbe, K., Leng, M.J., Pickering, M.D., Keely, B.J. 2009. A geological constraint on relative sea level in Marine Isotope Stage 3 in the Larsemann Hills, Lambert Glacier region, East Antarctica (31 366-33 228 cal yr BP). Quaternary Science Reviews, 28, 2689-2696.
Lakes in sub-Arctic regions have the potential of retaining many different aspects of water isotope composition in their sediments which can be used for palaeoclimate reconstruction. It is therefore important to understand the modern isotope hydrology of these lakes. Here we discuss the significance of variations in water isotope composition of a series of lakes located in north-west Swedish Lapland. Climate in this region is forced by changes in the North Atlantic which renders it an interesting area for climate reconstructions. We compare δ18Olake and δ2Hlake collected between 2001 and 2006 and show that lakes in this sub-Arctic region are currently mainly recharged by shallow groundwater and precipitation which undergoes little subsequent evaporation, and that the δ18O and δ2H composition of input to the majority of the lakes varies on a seasonal basis between winter precipitation (spring thaw) and summer precipitation.
Seasonal variations in the isotopic composition of the lake waters are larger in lakes with short residence times (<6 months), which react faster to seasonal changes in the precipitation, compared to lakes with longer residence times (>6 months), which retain an isotopic signal closer to that of annual mean precipitation. Lake waters also show a range of isotope values between sites due to catchment elevation and timing of snowmelt. The lake water data collected in this study was supported by isotope data from lake waters, streams and ground waters from1995 to 2000 reported in other studies.
Jonsson, C.E., Leng, M.J., Rosqvist, G.C., Seibert, J. Arrowsmith, C. 2009. Stable oxygen and hydrogen isotopes in sub-Arctic lake waters from northern Sweden. Journal of Hydrology, 376, 143-151.
Journal of the Geological Society - September 2009
Brachiopod carbonate from Early Permian brachiopod shells from low palaeolatitude north Iran and higher palaeolatitude Pakistan Karakorum were screened for diagenesis and analysed for oxygen isotope ratios to derive seawater palaeotemperatures. Screening techniques employed included SEM ultrastuctural analysis, cathodoluminescence (CL), image analysis of CL images, trace-element (Sr, Mn, Fe) determinations, and carbon and oxygen stable-isotope determinations. The Karakorum shells were found to be diagenetically altered, but those from north Iran were judged to be pristine. Using data from pristine material, two distinct time slices were analysed: the early and middle Asselian. The maximum calculated temperatures in the middle Asselian are about 2°C lower than those for the early Asselian. The average temperature for both time slices is similar to modern tropical sea-surface temperatures, indicating that low-latitude Early Permian ocean waters in Iran did not undergo significant cooling during the final Glacial III episode of Gondwanan glaciation.
This confirms other evidence based on biotic provinces, which suggests that during the Permo-Carboniferous glaciation, the low-latitude warm belt became narrower and confined to the western Tethys and Cathaysian provinces, and was not subject to a reduction in temperature, but rather a reduction in size.
Angiolini, L., Jadoul, F., Leng, M.J., Stephenson, M.H., Rushton, J., Chenery, S., Crippa, G. 2009. How cold were the Early Permian glacial tropics? Testing sea-surface temperature using the oxygen isotope composition of rigorously screened brachiopod shells. Journal of the Geological Society, London, 166, 933-945.
Rapid Communications in Mass Spectrometry - August 2009
Experimental calibration of the 18O/16O isotope fractionation between the biogenic aragonite of Viviparus contectus (Gastropoda) and its host freshwater was undertaken to generate a species specific thermometry equation. The temperature dependence of the fractionation factor, and the relationship between temperature, δ18Ocarb. and δ18Owater were calculated from specimens maintained under laboratory and field (collection and cage) conditions. Regression analysis indicated that the laboratory and field experiments produced clear but different linear trends and we have shown that the field cage thermometry equation is the most suitable for application to the fossil record. Comparisons made with existing aragonitic thermometry equations shows that the Viviparus contectus field collection and field cage equations are similar to those of both marine and freshwater aragonitic gastropods.
Caged specimens were grown (Somerset, UK) between February and August 2008, with water samples and temperature measurements taken monthly. Seasonal δ18O profiles from specimens retrieved from the field cage experiment indicate that during shell secretion the δ18O composition of the shell carbonate is not influenced by size, sex or whether females contained eggs or juveniles.
Bugler, M.J., Grimes, S.T., Leng, M.J., Rundle, S.D., Price, G.D., Hooker, J.J., Collinson, M.E. 2009. Generation of a Viviparus contectus thermometry equation through experimental calibration of oxygen isotopic fractionation. Rapid Communications in Mass Spectrometry,23, 2939-2951.
Journal of Archaeological Sciences - August 2009
Variations in the 13C/12C ratios of wheat grain at different spatial and temporal scales are examined by analysis of modern samples, including harvests of einkorn and durum wheat from Greece, and serve as a guide to interpreting data for Bronze Age grains from Assiros Toumba. The normal distribution and low variability of δ13C values of einkorn from 24 containers in the Assiros storerooms are consistent with pooling of local harvests, but less likely to represent the harvest of several years or include grain imported from further afield. Correlation between emmer and spelt δ13C values provides strong support for other evidence that these were grown together as a maslin crop. 13C discrimination for the Bronze Age samples is estimated to be 2.5‰ larger than at present, and would be consistent with the watering of the cereal crops as part of an intensive, horticultural regime of cereal cultivation.
Heaton, T.H.E., Jones, J., Halstead, P. and Tsipropoulos, T (2009). Variations in the 13C/12C ratios of modern wheat grain, and implications for interpreting data from Bronze Age Assiros Toumba, Greece. Journal of Archaeological Sciences, 36, 2224-2233.
Rapid Communications in Mass Spectrometry - August 2009
Rice accumulates large amounts of silicon which improves its growth and health due to enhanced resistance to biotic and abiotic stresses. Silicon uptake and loading to xylem in rice are predominantly active processes performed by transporters encoded by the recently identified genes. Silicon deposition in rice during translocation to upper plant tissues is known to discriminate against the heavier isotopes 29Si and 30Si resulting in isotope fractionation within the plant. We analyzed straw and husk samples of mutant rice both for silicon content and δ29Si using IRMS and compared these results with the corresponding wild type varieties. These initial results show the potential of Si isotopes to enlighten the influence of active uptake on translocation and deposition processes in the plant.
Köster, J.R., Bol, R., Leng, M.J., Parker, A.G., Sloane, H.J. and Ma, J.F. 2009. Effects of active silicon uptake by rice on 29Si fractionation in various plant parts. Rapid Communications in Mass Spectrometry, 23, 2398-2402.
Tracing migratory birds using 87Sr/86Sr isotopes. Jane Evans (NIGL) in collaboration with Rhys Bullman (Stirling University) show that migratory birds pick up a distinctive Sr isotope signature from their natal areas that can be used to help fingerprint their origins. Redshank hatched in Iceland have a significantly different isotope composition from those birds hatched in Scotland. The Icelandic redshank retain a distinctive signature even after they have flown to Scotland over winter and returned to Iceland. Stable isotopes have been used in the study of birds for many years, but the application of strontium isotopes adds a new dimension that can relate birds to the land rather than dietary remain of climate zone.
Evans, J. and Bullman, R. 2009. 87Sr/86Sr isotope fingerprinting of Scottish and Icelandic migratory shorebirds, Applied Geochemistry, doi: 10.1016/j.apgeochem.2009.07.006
Climate of the Past - July 2009
The rapid expansion of the Inca from the Cuzco area of highland Peru (ca. AD°1400-1532) produced the largest empire in the New World. Although this meteoric growth may in part be due to the adoption of innovative societal strategies, supported by a large labour force and a standing army, we argue that it would not have been possible without increased crop productivity, which was linked to more favourable climatic conditions. We present a multi-proxy, high-resolution 1200-year lake sediment record from Marcacocha, 12°km north of Ollantaytambo, in the heartland of the Inca Empire. This record reveals a period of sustained aridity that began from AD°880, followed by increased warming from AD°1100 that lasted beyond the arrival of the Spanish in AD°1532. These increasingly warmer conditions would have allowed the Inca and their immediate predecessors the opportunity to exploit higher altitudes (post-AD°1150) by constructing agricultural terraces that employed glacial-fed irrigation, in combination with deliberate agroforestry techniques.
There may be some important lessons to be learnt today from these strategies for sustainable rural development in the Andes in the light of future climate uncertainty.
Chepstow-Lusty, A.J., Frogley, M.R., Bauer, B.S., Leng, M.J., Boessenkool, K.P., Caarcaillet, C., Ali, A.A., Gioda, A. 2009. Putting the rise of the Inca Empire within a climatic and land management context. Climate of the Past, 5, 375-388.
Journal of the Geological Society, London - July 2009
Strontium isotope composition is increasingly being used to compare and provenance materials such as food and water and is also well established as a technique for looking at human origin and migration in archaeological studies. With these studies come the need for reference data against which the models of origin and transport can be tested. This paper presents the first attempt at biosphere 87Sr/86Sr mapping in the UK in order to make an understandable and useable data set for use in archaeological and forensic migration studies. The aim is to create a simplified map of isotope packages against which samples can be compared. The study assesses the merits of different biosphere sample types, for example, flora, fauna, and water, the effects of topography and surface cover, and considers the use of published 87Sr/86Sr data, from bedrock samples, as a method of estimating biosphere 87Sr/86Sr compositions. The Isle of Skye, Scotland, was chosen as the location for this pilot study because of the wide range of lithologies present which may be the source of both the high and the low 87Sr/86Sr ratios.
Evans, J.A. and Montgomery, J. and Wildman, G. 2009. Isotope domain mapping of 87Sr/86Sr biosphere variation on the Isle of Skye, Scotland, J. Geol Soc Lond. 166, 1-15.
Palaeogeography, Palaeoclimatology, Palaeoecology - July 2009
Lake Ashenge, a closed-basin lake near the northernmost penetration of summer monsoon rains, is well placed to provide a continental record of past changes in the strength of the African monsoon system. Diatom and oxygen isotope analyses of the lake sediments confirm the overall trend of climate change during the past 17,000 years was driven by precessional forcing, punctuated by abrupt shifts that may be linked to changes in Atlantic surface temperatures. The lake level was low from at least 17.2 to 16.2 cal kyr BP, and then rose between 16.2 and 15.2 cal kyr BP, which may represent a temporary reactivation of the monsoonal circulation system. The lake was significantly low between 13.6 and ~11.8 cal kyr BP coinciding approximately with the Younger Dryas, but beginning 900 years before its recognised onset in the Greenland ice-core record. A major sedimentary hiatus, covering the interval ~11.8 to 7.6 cal kyr BP, was probably caused by an early Holocene lowstand, the precise timing of which cannot be determined because pre-lowstand sediments were eroded from the core site.
The lake filled to its overflow from 7.6 cal kyr BP until 5.6 cal kyr BP, when the sediments record an abrupt lake response to the regional transition to arid conditions that mark the end of 'African Humid Period'. Evidence is also presented for climate changes which may have been associated with the rise and fall of Aksum, Ethiopia's first great civilisation.
Marshall, M.H., Lamb, H.F., Davies, S.J., Leng, M.J., Kubsa, Z., Umer, M. Climatic change in northern Ethiopia during the past 17,000 years: A diatom and stable isotope record from Lake Ashenge. Palaeogeography, Palaeoclimatology, Palaeoecology, 279, 114-127.
Journal of the Geological Society, London - June 2009
Laser ablation multi-collector ICP-MS analyses carried out at NIGL have helped to resolve a long-standing debate regarding assembly of different crustal blocks in the west of Ireland. U-Pb age spectra from detrital zircons contained in ca 464 Ma sandstones collected from South Mayo, Ireland indicate there were two different sources for sediments deposited over the same time interval. These different sources correspond to two distinct volcanic-arc phases on the Laurentian margin, with eastern and southerly derived strata having distinctly different middle to lower Ordovician detrital zircon signatures. The main conclusion from this study is that the Connemara block was proximal to the South Mayo Trough by at least 464 Ma. This is considerably earlier than previously envisaged.
MCCONNELL, B., RIGGS, N. and CROWLEY, Q.G., 2009. Detrital zircon provenance and Ordovician terrane amalgamation, western Ireland. Journal of the Geological Society, London, 166, 473-484.
Journal of the Geological Society, London - June 2009
This paper is underpinned by high-precision U-Pb TIMS analyses carried out at NIGL as part of a NIGFSC supported Ph.D. project (Joanne Neilson, University of Liverpool). It represents a considerable advance in the understanding of tectonic processes in relation to the timing of magmatism within the Grampian Highlands of Scotland and further afield. High-precision U-Pb zircon analyses indicate that magmatism at Glencoe and Lorn was continuous over a ca 22 m.y. period from about 425 Ma to 408 Ma. The post-collision magmatism and uplift resulted from break-off of subducted oceanic lithosphere and consequent rise of asthenosphere.
NEILSON, J.C., KOKELAAR, B.P. and CROWLEY, Q.G., 2009. Timing, relations and cause of plutonic and volcanic activity of the Siluro-Devonian post-collision magmatic episode in the Grampian Terrane, Scotland. Journal of the Geological Society, London, 166, 545-561.
Journal of the Geological Society, London - June 2009
Laser ablation ICP-MS analyses carried out at NIGL's PIMMS facility form the basis of this publication, which has arisen out of part of a NIGFSC supported Ph.D. project (Gavin Chan, University of Oxford). Accessory phases were analysed from granulite xenoliths brought up by an ultra-potassic dyke in southern Tibet. Dating of these accessory phases indicate that the crust below southern Tibet had reached a thickness of ca 80 km by 17-14 Ma and has remained unchanged until the present day.
CHAN, G.H., WATERS, D.J., SEARLE, M.P., AITCHISON, J., HORSTWOOD, M.S.A., CROWLEY, Q.G., LO, C.-H. and CHAN, J.S.-L., 2009. Probing the basement of southern Tibet: evidence from crustal xenoliths entrained in a Miocene ultrapotassic dyke. Journal of the Geological Society, London, 166, 45-52.
Sedimentology - June 2009
A detailed chemical and isotope profile through a 30-cm thick section of Silurian interbedded turbiditic and hemipelagic mudrocks from the central Wales Basin shows well-marked chemical and isotope trends. The variations reflect an interplay of depositional mode and diagenetic fractionation. Sm and Nd values are substantially higher and Sm/Nd ratios tend to be lower in the organic-rich hemipelagite layers due to diagenetic concentration in the hemipelagites. There is a corresponding depletion in the turbidite mudstones. The patterns seen in these rocks demonstrate the sensitivity of mudrock trace element and isotope compositions to both small-scale sedimentary structure and large-scale basin architecture.
EVANS, J.A., ZALASIEWICZ, J.A. and CHOPEY-JONES, A., 2009. Facies effects on the behaviour of Nd and Sr isotope systems in turbidite mudrocks during diagenesis. Sedimentology, 56, 863-872.
Archaeometry - June 2009
Carbonized plant remains are found worldwide in many archaeological contexts, often in association with charred wood from hearths or as a result of deliberate or accidental burning. However, in many burial environments, uncarbonized plant material is prone to decay and this disparity in survival raises the possibility that the carbonization process creates a stable carbon structure that is resistant to chemical and biological degradation. Strontium isotope analysis has been successfully used to provenance modern foodstuffs such as wine and water as a tool for human migration studies and to establish the origin of archaeological plant material. However, for archaeological studies, it is imperative to demonstrate that post-mortem alteration has not affected the material analysed to any significant degree. Tooth enamel has been shown to be a reasonably reliable archive of lifetime strontium values, because its biogenic integrity is minimally compromised during burial as a result of the dense,felted, inorganic structure. In contrast, there is little evidence to demonstrate the biogenic integrity of strontium within ancient plant material recovered from archaeological sites.
HEIER, A., EVANS, J.A. and MONTGOMERY, J., 2009. The potential of carbonized plant material to preserve its 87Sr/86Sr life time signature within the burial environment. Archaeometry, 51, 277-291.
Mineralogical Magazine - June 2009
Jurassic dykes of western Dronning Maud Land (Antarctica) form a minor component of the Karoo large igneous province. An extensive local dyke swarm intrudes Neoproterozoic gneisses and Jurassic syenite plutons on the margins of the Jutulstraumen palaeo rift in the Svedrupfjella region. The dykes were intruded in three distinct episodes (~204 Ma, ~176 and ~170 Ma). The 204 Ma dykes are overwhelmingly low-Ti, olivine tholeiites including some primitive (picritic) compositions (MgO >12wt.%; Fe2O3 >12 wt.%; Cr >1000 ppm; Ni >600 ppm). This 204 Ma event precedes the main
Karoo volcanic event by~25 Ma, so any correlations to the wider province are difficult to make. However, it may record the earliest phase of rift activity along the Jutulstraumen. The 176 Ma dyke event is more intimately associated with the two syenite plutons. The dykes are alkaline (basanite/
tephrite) and were small-degree melts from an enriched, locally derived source and underwent at least some degree of interaction with a syenitic contaminant.
This ~176 Ma dyke event is widespread elsewhere in the Karoo (southern Africa and Dronning Maud Land). Later-stage (170 Ma) felsic
(phonolite-comendite) dykes intrude the 176 Ma basanite-tephrite suite and represent the last phase of magmatic activity in the region.
RILEY, T.R., CURTIS, M.L., LEAT, P.T. and MILLAR, I.L., 2009. The geochemistry of Middle Jurassic dykes associated with the Straumsvola - Tvora alkaline plutons, Dronning Maud Land, Antarctica and their association with the Karoo large igneous province. Mineralogical Magazine, 73(2), 223-244.
The stable isotope data extend and expand upon previous isotopic investigations of the Middle to Late Jurassic interval. The belemnite samples collected from the Staffin Bay and Staffin Shale formations from the Isle of Skye, Scotland, yielded oxygen isotope values consistent with Callovian-Kimmeridgian palaeotemperatures of 6.7-20.6 oC. The carbon isotope data comprise one of the first investigations of the relationship between terrestrial δ13Corg (predominantly fossil wood debris) and marine δ13Ccarb (belemnites) as derived from a geologically coeval record. The Staffin Bay data reveal a broad Early to Mid-Oxfordian positive carbon isotope excursion. The excursion maximum occurs in the cordatum Zone (British Boreal ammonite zonation), although high values persist into the tenuiserratum Zone. The correspondence between the marine and terrestrial records indicates a strong coupling of the ocean-atmosphere system and suggests that the total exchangeable carbon reservoir would have been affected at this time.
The Mid-Oxfordian negative carbon isotope excursions identified in published Tethyan records and commonly attributed to methane release are not recorded in the Staffin Bay data, which may suggest that the Tethyan excursions do not represent fluctuations in the global carbon reservoir and that the fidelity of the methane hypothesis should be re-evaluated.
Nunn, E.V., Price, G.D., Hart, M.B., Page, K.N., Leng, M.J. 2009. Isotopic signals from Callovian_Kimmeridgian (Middle_Upper Jurassic) belemnites and bulk organic carbon, Staffin Bay, Isle of Skye, Scotland, Journal of the Geological Society, 166, 633-641.
The sedimentary record from the paleolake at Les Echets in eastern France allowed a reconstruction of the lacustrine response to several abrupt climate shifts during the last glacial period referred to as Dansgaard-Oeschger (DO) cycles. The high-resolution diatom stratigraphy has revealed distinct species turnover events and large fluctuations in stable oxygen isotope values in diatom frustules, as a response to DO climate variability. More or less identical species compositions became re-established during each DO stadial and interstadial phases, respectively. However, the relative abundance of the most dominant species within these assemblages varies and might indicate differences in climatic conditions. Interstadial phases are characterized by identical species successions.
Transitions from stadial to interstadial conditions show a distinct Fragilaria-Cyclotella succession, which resembles the diatom regime shifts that have been recognized in some lakes in the Northern Hemisphere since the mid-19th century.
Ampel, L., Wohlfarth, B., Risberg, J., Veres, D., Leng, M.J., Kaislahti Tillman, P. 2009. Diatom assemblage dynamics during abrupt climate change: the response of lacustrine diatoms to Dansgaard-Oeschger cycles during the last glacial period. Journal of Palaeolimnology, DOI 10.1007/s10933-009-9350-7.
Late Quaternary vegetation history and environmental changes in a biodiverse tropical ecosystem are inferred from pollen, charcoal and carbon isotope evidence derived from a ~48,000 yr sedimentary record from the Uluguru Mountains, a component of the Eastern Arc Mountains of Kenya and Tanzania. Results indicate that Eastern Arc forest composition has remained relatively stable during the past 48,000 yr, resulting in the diverse forests observed today. The pollen and isotope data presented indicate no significant loss in moist forest taxa through the last glacial maximum, thereby providing support for the long-term environmental stability of the Eastern Arc. Anthropogenic activities, including burning and forest clearance, were found to play a moderate role in shaping the mosaic of forest patches and high altitude grasslands which characterise the site today; however this influence was tempered by the inaccessibility of the mountain.
Finch, J.M., Leng, M.J., Marchant, R.A. 2009. Late Quaternary vegetation dynamics in a biodiversity hotspot, the Uluguru Mountains of Tanzania. Quaternary Research, 72, 111-122.
Journal of Geophysical Research Atmosphere - April 2009
Large and abrupt temperature oscillations during the last glacial period, known as Dansgaard-Oeschger (DO) events, are clearly observed in the Greenland ice core record. Here we present a new high-resolution chemical (2 mm) and stable isotope (20 mm) record from the North Greenland Ice Core Project (NGRIP) ice core at the onset of one of the most prominent DO events of the last glacial, DO-8, observed ~38,000 years ago. The unique, subannual-resolution NGRIP record provides a true sequence of change during a DO warming with detailed annual layer counting of very high depth resolution geochemical measurements used to determine the exact duration of the transition.
The continental ions, indicative of long-range atmospheric loading and dustiness from East Asia, are the first to change, followed by the snow accumulation, the moisture source conditions, and finally the atmospheric temperature in Greenland. The sequence of events shows that atmospheric and oceanic source and circulation changes preceded the DO warming by several years.
Thomas, E. R., E. W. Wolff, R. Mulvaney, S. J. Johnsen, J. P. Steffensen, and C. Arrowsmith. 2009. Anatomy of a Dansgaard-Oeschger warming transition: High-resolution analysis of the North Greenland Ice Core Project ice core, J. Geophys. Res., 114, D08102, doi:10.1029/2008JD011215.
The Carbon Isotope Excursion associated with the Paleocene-Eocene Thermal Maximum has been detected for the first time in the total organic carbon contained within the continental sediments of the South Central Pyrenees. Previous studies have detected the CIE in the South Central Pyrenees in both marine and soil carbonates. These studies have located the onset of the CIE either above or within the Claret Conglomerate, interpreted as a megafan produced by a change in the precipitation regimen at the beginning of the PETM. Our higher resolution δ13CTOC study places the onset of the CIE below the base of the Claret Conglomerate and therefore suggests a 4 to 9 kyr time lag between the onset of the CIE and an increase in intense seasonal precipitation rates.
Furthermore, this study suggests that the CIE took place ~30-55 kyr after the deposition of important late Cernaysian Tremp mammalian sites which contain the youngest known occurrence of endemic Paleocene mammalian taxa in Europe.
Domingo, L., López-Martínez, N., Leng, M.J., Grimes, S.T. 2009. The Paleocene-Eocene Thermal Maximum record in the organic matter of the Claret and Tendruy continental sections (South Central Pyrenees, Lleida, Spain). Earth and Planetary Science Letters, 281, 226-237.
The mid-Carboniferous strata of northern England are characterised by mixed clastic-carbonate cycles (Yoredale cycles), attributed to the short eccentricity Milankovitch rhythm. In a typical cycle, transgressive normal-marine shelf carbonates are succeeded by marine shales, then highstand prodelta mudstones and delta front-delta top sandstones with local coals. It is inferred that millennial-scale climatic changes occur within the Carboniferous, and were responsible for the deposition of the beds that are a characteristic feature of many marine sedimentary successions in the geological record. The most likely over-riding control is fluctuations in solar output.
Tucker, M.E., Gallagher, J., Leng, M.J. 2009. Are beds in shelf carbonates millennial-scale cycles? An example from the mid-Carboniferous of northern England. Sedimentary Geology, 214, 19-34.
Journal of Analytical Atomic Spectrometry - March 2009
Sample preparation and analytical techniques have been 'borrowed' from geochronology for a novel application in nuclear forensics. This paper demonstrates for the first time, the application of high precision isotope ratio LA-MC-ICP-MS analyses to a large population of individual uranium-oxide grains from environmental samples. These data reveal details of the history of uranium processing in Colonie, NY, USA. The research is part of an environmental case-study investigating the distribution of depleted uranium contamination surrounding a former munitions factory.
Lloyd, N.S., Parrish, R.R., Horstwood, M.S.A., and Chenery, S.R.N. (2009) Precise and accurate isotopic analysis of microscopic uranium-oxide grains using LA-MC-ICP-MS. Journal of Analytical Atomic Spectrometry. DOI: 10.1039/b819373h
Measurements of diatom oxygen isotopes hold the potential to provide an important additional source of palaeoceanographic information in regions depleted in carbonates. However only a handful of studies have applied δ18Odiatom in marine reconstructions. Here the historical development and current state of affairs concerning the usage of δ18Odiatom in palaeoceanography is reviewed. This includes a summary of sample purification and analytical techniques, existing palaeoceanographic reconstructions, vital effects and secondary isotope exchanges; and a review of the current and future developments required to improve the reliability of δ18Odiatom based reconstructions in palaeoceanography.
Swann, G.E.A. and Leng, M.J. 2009. A review of diatom δ18O in palaeoceanography. Quaternary Science Reviews, 28, 384-398.
Journal of Archaeological Science - February 2009
Following on from the recent paper detailing the application of LA-MC-ICP-MS to Sr isotope analyses of teeth and bones (Horstwood et al 2008, GCA, see earlier highlight), NIGL scientist Matt Horstwood (in collaboration with Geoff Nowell of Durham University) has further detailed the approach required for this complex analysis in a formal comment to a paper published in the Journal of Archaeological Science. The comment demonstrates that far from interpreting Neanderthal mobility from data from an ancient tooth, the data more likely indicate immobility once appropriately corrected. Regardless of the scientific interpretation of the data, this paper demonstrates further the problems that can beset LA-ICP-MS isotope data when complex matrix derived interferences are present.
Nowell, G.M., Horstwood, M.S.A. Comments on Richards et al. Journal of Archaeological Science 35, 2008 "Strontium isotope evidence of Neanderthal mobility at the site of Lakonis, Greece using laser-ablation PIMMS", Journal of Archaeological Science (2009), doi: 10.1016/j.jas.2009.01.019
Now for the science bit...an article by Melanie Leng, Tim Heaton and Jane Evans on the value of stable isotopes to todays policy makers: issue 20, pages 220-221.
April 2010 Planet Earth News High and dry in the Andes.
The Spring 2010 edition of Planet Earth reports on a project in which NIGL joined forces with Dr Mick Frogley (Sussex) and Dr Alex Chepstow-Lusty (Lima) to understand how the indigenous cultures in Peru coped with limited water supplies in the past.
April 2010 Planet Earth News Finding the wisdom in teeth.
The Spring 2010 edition of Planet Earth reports on a project in which NIGL uses isotope techniques to shed new light on the origins of archaeological finds and human migration in prehistoric Britain.
NERC Isotope Geosciences Laboratory's Dr Jane Evans talks to Planet Earth online about how she figured out that a pit full of decapitated bodies in Dorset were Vikings.... I'm not aware of many other burial sites in this country with this level of slaughter. It's particularly unusual says Dr Jane Evans.
March 2010 Decapitated bodies - isotopes show they were Vikings.
The decapitated individuals found in a mass grave in Dorset last year are of Scandinavian origin. Isotope analysis of tooth enamel and dentine from ten individuals was carried out at NIGL for Oxford Archaeology and Dorset County Council. The results show that they all came from a region with a colder climate than Britain, such as Norway or Sweden. Their diet matches better with Scandinavian medieval diets than with Anglo Saxon ones. The isotope results show considerable variation, indicating that these individuals came from a number of different locations within Scandinavia.
Stonehenge bones may be evidence of winter solstice feasts
Professor Mike Parker Pearson of the University of Sheffield and his team including Dr Jane Evans (NIGL) have just won a grant of £800,000 from the Arts and Humanities Research Council, to answer some of the riddles about the enigmatic prehistoric Stonehenge monument.
27 October 2009 - PlanetEarth Online NEWS: Bronze Age cattle travelled long distances, by Sara Coelho
Show me your teeth and I'll tell you where you're from: archaeologists analysing isotopes in tooth enamel from cattle buried at two Bronze Age barrows have found that at least some of the animals originated from elsewhere, revealing long-distance trading networks in ancient Britain.
Jacqueline Towers, Janet Montgomery, Jane Evans, Mandy Jay, Mike Parker Pearson. An investigation of the origins of cattle and aurochs deposited in the Early Bronze Age barrows at Gayhurst and Irthlingborough. 2009 doi: 10.1016/j.jas.2009.10.012
One of our recent papers was highlighted this month in Nature:
Chepstow-Lusty, A.J., Frogley, M.R., Bauer, B.S., Leng, M.J., Boessenkool, K.P., Caarcaillet, C., Ali, A.A., Gioda, A. 2009. Putting the rise of the Inca Empire within a climatic and land management context. Climate of the Past, 5, 375-388.
Archaeology: Maya, Khmer and Inca, page 479
Past societies have struggled against environmental problems similar to those that beset us today. This publication (one of three discussed) illuminates the outcomes for tropical civilizations during the period AD 7001600. By Jared Diamond.
July 2009 - Planet Earth News - Malta has a serious nitrate pollution problem. But where is it all coming from?
The Summer 2009 edition of Planet Earth reports on a project in which NIGL joined BGS hydrologists to conduct an isotope and geochemical survey of groundwater in Malta.
The country is one of the most densely populated in the world, with over 80% of the land either built upon or used for intensive arable and livestock farming. Our detailed 15N/14N and 18O/16O survey demonstrated that these activities have led to Maltas groundwater having the most widespread nitrate pollution in the EU.
J. Geophys. Res. 114, D08102 (2009): The last glacial period was punctuated by abrupt transitions to interstadial (warm) conditions. An analysis of an event 38,000 years ago as recorded in the ice core from the North Greenland Ice Core Project reveals that mid-latitude climate change preceded Greenland warming by several years.
Elizabeth Thomas of the British Antarctic Survey and colleagues (including Carol Arrowsmith of NIGL) used multiple proxies to reconstruct climatic conditions during this abrupt warming, one of the most prominent of the last glacial period. The ice core's annual layers showed that the approximately 11°C warming over Greenland occurred over about 26 years. However, the team also found that a few years before the warming kicked in, the dust supply from Asia declined, which they relate to a strengthening of the summer monsoon.
At about the same time, there was a shift in the hydrogen and oxygen isotopes of the ice, suggesting a northward migration of the polar front.
The lag between the strengthening of the Asian monsoon and Greenland warming could point to a trigger for glacial abrupt climate change in the tropics or the Southern Hemisphere, rather than the north.
June 2009 - Planet Earth News - Burned grains hold clues to ancient farms
A granary that burned down 2300 years ago stored wheat from a single, carefully farmed harvest, research suggests. The findings are based on chemical comparisons of old and modern wheat grains and give new insights to Bronze Age farming practices.
A granary at Assiros Toumba in Greece was burned to the ground around 1300 BC, during the Bronze Age, together with large quantities of grain stored in clay bins and jars. It was a large facility and the fire was undoubtedly a catastrophic accident for the people whose grain was stored there. The reasons for the fire are unknown. Archaeologists also did not know what kind of wheat was in store at Assiros Toumba: was it all from the same year, or from different harvests? Was it the product of local farmers or a regional storage centre? One way to answer these questions is to look at the wheat grains carbon stable isotopes. The analyses of the old wheat grains show that the carbon isotope ratios are very similar and the differences are within the natural variations observed in a single modern wheat field. The lack of variation suggests that all the wheat in Assiros Toumba comes from a single years harvest gathered over a small area, write the authors in the report published this week in the Journal of Archaeological Science.
The ancient carbon isotope ratios also suggest that the Assiros Toumba wheat grew with plenty of water. As there is no evidence for higher rainfall during the Bronze Age, the findings suggest that the crops were well watered by the farmers, who also kept the fields free from weeds that might have competed with the wheat for moisture. The results help to provide a better understanding of farming practices in the Assiros Toumba region during the Bronze Age. Farmers kept intensive, well-watered and weed free wheat fields and stored the harvest in communal storage rooms, perhaps controlled by ruling elites.
Tim H.E. Heaton, Glynis Jones, Paul Halstead, Taxiarchis Tsipropoulos. Variations in the 13C/12C ratios of modern wheat grain, and implications for interpreting data from Bronze Age Assiros Toumba, Greece. Journal of Archaeological Science. Available online 21 June 2009
Professor Randy Parrish: Tracking time of the Earth and Solar System, Geological Society of London: Shell London Lecture Series, 13th May 2009
Abstract: The current estimate of the age of the earth (and the accretion of the other planets) is close to 4,567 million years before present, a value that has been refined progressively since the discovery of radioactivity and its implications to the evolution of the earth. The science (and to some extent art) of geo- and cosmo-chronology underpins this ancient age and involves a huge array of technical and scientific achievements where more precise estimates increasingly depend upon ever more precise measurement of tiny amounts of rare terrestrial and extraterrestrial material. The reliability of the measurements and their evolution of techniques can be traced back to metrology, or the science of measurement. Much of what we know about the earth and its evolution is made possible because of geochronology, without which the duration and rate of events cannot be determined with any certainty in the geological record. In fact testing hypotheses regarding the synchronicity of global events (extinctions, rapid climate excursions, etc.) and determining cause and effect (bolide impact leading to extinctions) is crucially dependent on further refinements of precision and accuracy in geochronology.
The lecture will wander through earth and cosmic events and highlight some of the more interesting advances in thinking and method that have shaped our view of the antiquity of the earth and its methods of time keeping.
Sir David Attenborough and The Tree of life: screened 9pm BBC1, Sunday 1st February 2009
NIGL is privileged to have been asked to contribute to a one-off BBC special documentary in which Sir David Attenborough discusses evolutionary 'fact' and the contribution of the great Charles Darwin in this the bicentennial anniversary of his birth and the 150th anniversary of the publication of his great work Origin of Species. The BBC team filmed various aspects of the process of zircon dating over the course of their visit. In the end, a small segment filmed in the PIMS lab showing laser ablation U-Pb analysis of zircon crystals from Charnwood Forest was used in the program to highlight the ability to determine the age of deposits containing fossils of early multi-cellular life.
The programme can be viewed again via the BBC website.
Bering Sea diatom isotope records during the onset of Northern Hemisphere Glaciation
The progressive advancement of ice-sheets across the Northern Hemisphere in the late Pliocene and the development of glacial-interglacial cycles which punctuate the Quaternary marks a significant threshold in the Earth's climate history. Of particular note are the transitions associated with the onset of major Northern Hemisphere Glaciation (NHG), c. 2.85-2.73 Ma, when large ice-sheets developed across Greenland, Eurasia and Northern America. This project aims to investigate the nature of these changes in the Bering Sea by measuring diatom δ13C, δ18O and δ30Si from 3.2-2.5 Ma at IODP Site U1341. Situated south of the sea-ice extent at the western flank of Bowers Ridge, the results will permit an assessment of linkages between the Pacific Ocean and Bering Sea with regards to meltwater influx and the biological pump.
Establishing an understanding of the latter is critical for determining the role of the oceans in regulating atmosphere CO2 concentrations over this time-frame.
This project is headed by George Swann (NIGL) and includes Andrea Snelling (NIGL) and Jenny Pike (Cardiff).
June 2010: Prof Randy Parrish receives Murchison Medal
Congratulations to Randy for being awarded the Murchison Medal by the Geological Society of London. The Murchison Medal is awarded to people who have made a significant contribution to science by means of a substantial body of research. Council looks at breadth as well as depth in pure and applied hard rock science.
The Svalbard exemplar of Neoproterozoic glaciation
Although life successfully moderates surface conditions on Earth, some events in Earth History have threatened the viability of most life forms. Arguably the most profound and long-lasting challenge in the last 2 billion years was glaciation on a near-global scale, with the best documented event being around 650 to 630 million years ago ("Marinoan" glaciation). The Snowball Earth hypothesis proposes that snow and ice became so widespread that the Earth become much more reflective of solar radiation and cooled to a mean temperature of around -50 degrees Celsius. Glaciation was eventually terminated by the build-up of carbon dioxide emitted from volcanoes, that was not used up by the weathering of rocks since rocks were buried beneath the extensive snow and ice cover. Almost all facets of the Snowball Earth hypothesis, and of alternative hypotheses, are open to challenge, there is general agreement that glaciation reached tropical latitudes at sea level.
New lines of evidence are needed to refresh the debates and constrain future modelling efforts.
This project is headed by Ian Fairchild (Birmingham) and includes Dan Condon (NIGL) as a Co-I.
April 2010: NERC AFI grant
Terrestrial Holocene climate variability on the Antarctic Peninsula
The Antarctic continent is an important part of the Earth system, both influencing and responding to global ocean and atmospheric circulation. A key question in understanding and attribution of Antarctic climate change is whether the recorded changes on the Peninsula are unusual compared with past natural climate variability. Moss banks are ideal deposits for reconstructing climate change over the land surface of the Antarctic Peninsula because of their location in relation to recorded temperature changes, their age, and their attributes as archives.
The moss banks have accumulated peat over the past 5-6000 years at locations throughout the western Antarctic Peninsula. They are formed of only one or two species, annual growth can be traced in the surface peats and preservation of moss remains is good. We will use multi-proxy indicators of past climate (stable isotopes, measures of decay, testate amoebae and moss morphology) to reconstruct climate variability from critical locations across the observed gradient in rate of temperature change between 69o and 61o S.
This project is headed by Dan Charman (Exeter) with Melanie Leng (NIGL) as a project partner.
February 2010: New funding - British Isotopes in Rainfall Project
This new project, in association with The Climatological Observers Link (COL) and other selected rainfall observation stations, aims to map the variability in oxygen and hydrogen isotopes in UK rainfall initially over a series of rainfall events in March 2010. The project is being run by Dr Matt Jones (Nottingham), Dr Jon Tyler (Oxford) and Prof Melanie Leng (NIGL).
Dating the "Taung Child" Australopithecus africanus type specimen through U-Pb measurements of associated calcite crystals
The "Taung Child" was found in 1924 at the Buxton limestone quarry, Northwestern Province, South Africa. The "Taung Child" was the first early hominid found in Africa and became the type specimen of Australopithecus africanus. Mining activities continued at the quarry and the geological context of the specimen was lost, hampering attempts to date the hominid and understand its ecological context. Because of this, current estimates for the age of the "Taung Child" range from 3 million to 1 million years old. Such chronological uncertainty greatly hampers our understanding of early hominid evolution in Africa. We propose to take samples of calcite crystals attached to the endocast of the "Taung Child" and other associated fossils for uranium-lead dating using state-of-the-art facilities at the NERC Isotope Geosciences Laboratory. Pilot evidence demonstrates the suitability of such calcite crystals for high-precision age determination, and permission to sample the calcites has been granted by the Hominid Access Committee.
The proposed radiometric dates for the "Taung Child" are likely to alter the current age-range for Australopithicus africanus, perhaps changing our understanding of ancestor-decendant relationships among early hominin species.
The methods undertaken in this study can be applied to other early hominin specimens from the "Cradle of Humankind" World Heritage Site, South Africa, thereby improving the chronology of human evolution in Africa, and the methods will be refined to maximize the scientific information obtained from the minimum use of valuable fossil material, thereby improving generic methods of analysis of rare and invaluable museum collections.
This project is headed by Prof Randy Parrish (NIGL), with Dr Philip Hopley, Birkbeck College London; Dr Colin Mentor, University of Johannesburg; and Dr Bernhard Zipfel, University of the Witwatersrand.
January 2010: NERC Small grant
Critically testing the role of δ30Si (diatom) as a novel productivity signal in temperate lakes.
Despite occupying only ~3% of the earth's land surface, lakes are productivity hotspots and play an important role in the biological fixing, mineralisation and burial (collectively cycling) of carbon, at both a landscape and global scale. Lakes are sensitive to environmental change, yet the ways that lake ecosystems respond (in terms of their overall structure, and processes such as lake productivity) are poorly understood. A NERC-funded project aims to characterise the seasonal dynamics of silicon and δ30Si and link these to diatom productivity in an eutrophic, freshwater lake (Rostherne Mere, Cheshire, UK) to test critically the use of δ30Sidiatom as a productivity proxy in freshwater systems. New analytical developments also make it possible to measure δ18O in diatom silica from the same samples, thus providing the opportunity to link δ30Si and diatom productivity to climatic and hydrological variability. We will monitor bulk sediment formation, planktonic diatom dynamics, climate, hydrology and lake function (stratification) over an 18-month period (including two spring seasons) at high resolution by means of automatic traps, automatic water sampler, on-lake weather station, and a thermistor chain.
The team of researchers include: Dr David Ryves (Loughborough University), Dr Jon Tyler (Oxford University) and Prof Melanie Leng (NIGL) and Dr Phillip Barker (Lancaster University).
2010 Schlumberger Medal of the Mineralogical Society
Congratulations to Professor Randy Parrish who has been awarded the 2010 Schlumberger Medal of the Mineralogical Society.
This annual award was founded in 1990 through the generous sponsorship of Schlumberger Cambridge Research and has the purpose: To recognize scientific excellence in mineralogy and its applications; mineralogy being broadly defined and reflecting the diverse and worldwide interests and membership of the Society with its various specialist groups. Evidence of such excellence should be in the form of published work by a currently active scientist. Professor Parrish will be presented with this award at the 44th Annual conference of the Volcanic and Magmatic Studies Group in Glasgow in January 2010.
August 2009: Leverhulme grant success
Evaluating Hunter-Gatherer Subsistence Strategies in Late-Glacial Central Italy. PI Dr R. Donahue (Bradford) with Dr Jane Evans (NIGL)
This 3-year interdisciplinary research programme will evaluate two competing models of dietary and mobility strategies of hunter-gatherers in Mediterranean Europe during the Late-glacial and early Holocene (~;20,000--~8,000 BP). Research has led to the hypothesis that the Broad Spectrum Revolution, characterised by the diversification of food resources prior to the origins of agriculture in the Middle East, began during the Upper Palaeolithic throughout the Mediterranean region. The Seasonal Mobility hypothesis, previously proposed, presents foragers during the Late-glacial in Mediterranean Europe as highly specialised hunters of herd species, primarily the steppe horse and red deer, which migrated between highland meadows in summer and coastal plains in winter. Both hypotheses are supported by archaeological evidence, but are theoretically mutually exclusive. The first model predicts increasing sedentism and regionalization of resource exploitation, while the second predicts highly mobile, specialized hunters. Resolving this problem has major implications on the roles of logistic and residential mobility during the Upper Palaeolithic, for hunter-gatherer responses in dynamic environments with abrupt climate change, for palaeodemography at the end of the Pleistocene, and for the adoption of agriculture in Mediterranean Europe.
The international team will integrate innovative scientific techniques with established archaeological methods to test critical expectations of these models. Central Italy is exceptionally appropriate for this study as it contains a rich archaeological record for the Late-glacial and has been a source of inspiration for both hypotheses.
August 2009: AHRC grant success
Feeding Stonehenge: provisioning henges and households in southern Britain in the 3rd millennium BC, PI's Mike Parker Pearson (Sheffield) and Dr Jane Evans (NIGL)
The great henge complexes of southern Britain have long been recognised as ceremonial sites for large-scale feasting by gatherings of people who probably came from far and wide. Yet we have little indication of the catchment or hinterland of Stonehenge and its close neighbours Woodhenge and Durrington Walls, or of the other 3rd millennium BC Wessex henge complexes where feasting debris is prolific. Were these henges the foci of competing polities within the Wessex chalklands or were they destinations for celebration at specific moments in a calendrical round? Nor do we know much about the rearing and movement of livestock slaughtered at these sites, or the details of henge-builders' provision and consumption. The 2003-2007 excavations at Durrington Walls, largely funded by AHRC, have uncovered an unexpectedly well-preserved and artefact-rich Neolithic settlement with surviving house floors and their debris, yard compounds with middens identifiable to particular houses, and distinct zoning between public and private spaces. These present a unique opportunity for a detailed economic study of the Stonehenge people at nested scales from household to henge community.
July 2009: The Geological Society of America elected Fellow
Professor Randy Parrish has been elected Fellow of the GSA for innovative development and application of geochronology and geochemistry to tectonics and crustal evolution. He will be recognised at the 2009 GSA Annual Meeting in Portland.
February 2009: British Academy Small Grant Success
Where did the Iron Age chariot builders of East Yorkshire come from?
This long-standing puzzle for British archaeology may soon be solved. Dr. Janet Montgomery has been awarded a grant from the British Academy to investigate the geographic origins of Iron Age people of the East Yorkshire Wolds, in particular the ‘chariot' burials, using isotopic analysis of skeletal material. Her co-investigators are Dr. Mandy Jay, University of Durham and Dr. Jane Evans, NIGL and Jacqueline Towers, a recent University of Bradford MSc graduate. The project is being undertaken with the support of the Hull and East Riding Museum and the British Museum.
The Archean-Proterozoic Transition: Constraining the Emergence of Modern Aerobic Earth System.
NIGL is part of a NERC supported UK team (with partners at SUERC and University of St Andrews) of the Fennoscandia Arctic Russia - Drilling Early Earth Project (FAR-DEEP) project. FAR-DEEP is an internationally supported (including ICP, NASA, NERC, German Deutsche Forschungsgemeinschaft, Norwegian Science Council, Geological Survey of Norway, USA NSF, and University of Bergen) project with one overarching goal: to develop a comprehensive, self-consistent model explaining the transformation of Earth from an anoxic to oxic planet and the subsequent transition to an aerobic Earth System. The excellent rock archive obtained by the FAR-DEEP drilling provides the opportunity to obtain the necessary and sufficient data to resolve questions of 'how' and 'when' Earth became oxygenated and define a comprehensive, self-consistent biogeochemical model of Earth's transition to an oxic state.
This affords a unique chance to integrate outcrop and core data into an all-inclusive model of Archaean-Palaeoproterozoic Earth System evolution using isotope geochemistry and modelling, geochronology, geobiology, igneous petrology, palaeomagnetism, sedimentology and basin analysis.
There are opportunities for a three year PDRA position focussed on the development of a highly-resolved and robust temporal framework for this interval. Expressions of interest are very welcome - contact Dan Condon for more information.
January 2009: Successful NERC Standard Grant
Diatom Silica Oxygen Isotope Records from the Late Quaternary Antarctic Margin (2009-2011).
The project led by Melanie Leng and George Swann at NIGL and Jenny Pike at Cardiff aims to understand the role of the Antarctic ice sheets in the global ocean-atmosphere system with a view to understanding their potential future variability under a warming climate. Exceptionally well-preserved Antarctic margin sediment cores contain an excellent archive of these ice-ocean-climate interactions, often on seasonal timescales, from the end of the last ice age and throughout the recent warm interglacial. Diatom oxygen isotope measurements provide a means of obtaining oxygen isotope records in high latitude environments. The measurement of oxygen isotopes in diatoms will be used to investigate changes in salinity, freshwater input and sea surface temperature. The research proposed here will be the first attempt to produce diatom oxygen isotope records from the Antarctic margin, a region sensitive to the waxing and waning of the Antarctic ice sheets in terms of melt water through-put to the Southern Ocean.
Figure: Sediment core (left to right, clockwise) showing spring and summer diatom blooms, diatoms and diatom ornamentation from deglacial sediments from Antarctica
From 4-6th April 2011, the next IBIS meeting will take place in Antwerp, Belgium. It will be hosted in the historical city campus buildings of the University of Antwerp. During our 3-day programme, we would like to host a diverse meeting for everyone involved in research of biological silica cycling. We hope everyone will join for the first International IBIS-meeting. We will have a diverse programme with 3 invited speakers (Olivier Ragueneau and 2 others yet to be decided) and sessions on various aspects of the terrestrial, coastal and ocean biogenic silica cycle, isotopes in biogenic silica and their applications, and the importance of biological Si cycling in global Si budgets.
Registration will start from November 1st 2010, when we will have the names of all our invited speakers, and registration facilities will be opened. Please check our website for regular updates. We will also send around more circulars in the coming months.
The meeting organizers are:
Eric Struyf, Jonas Schoelynck, Floor Vandevenne, Sander Jacobs and Patrick Meire
Bradley, C., Baker, A., Jex, C.N., Leng, M.J. 2010. Hydrological uncertainties in the modelling of cave drip-water δ18O and the implications for stalagmite palaeoclimate reconstructions. Quaternary Science Reviews, 29, 2201-2214.
Swann, G.E.A. 2010. A comparison of the Si/Al and Si/time wet-alkaline digestion methods for measurement of biogenic silica in lake sediments. Journal of Paleolimnology, 44, 375-385.
D.J. Smith, G.R.T. Jenkin, J. Naden, A.J. Boyce, M.G. Petterson, T. Toba, W.G. Darling, H. Taylor, I.L. Millar. 2010. Anomalous alkaline sulphate fluids produced in a magmatic hydrothermal system – Savo, Solomon Islands. Chemical Geology, 275, 35-49.
Hastie,A.R., Kerr, A.C., McDonald, I., Mitchell, S.F., Pearce, J.A., Wolstencroft, M. and Millar, I.L. 2010. Do Cenozoic analogues support a plate tectonic origin for Earth's earliest continental crust? Geology, 38, p495-498.
Jex, C., Baker, A., Fairchild, I.J., Eastwood, W., Leng, M., Sloane, H., Thomas, L., Bekaroglu, E. 2010. Calibration of speleothem δ18O with instrumental climatic records from Turkey. Global and Planetary Change, 71, 207-217.
Hodson, A, Heaton, T, Langford, H, Newsham, K. 2010. Chemical weathering and solute export by meltwater in a maritime Antarctic glacier basin. Biogeochemistry, 98, 9-27.
Yu, F., Zong, Y., Lloyd, J.M., Huang, G., Leng, M.J., Kendrick, C., Lamb, A.L., W.-S Yim, W. 2010. Bulk organic δ13C and C/N as indicators for sediment sources in the Pearl River delta and estuary, southern China. Estuarine, Coastal and Shelf Science, 87, 618-630.
Hibbert, F.D., Austin, W.E., Leng, M.J., Gatliff, R.W. 2010. British ice sheet dynamics inferred from North Atlantic ice-rafted debris records spanning the last 175,000 years. Journal of Quaternary Science, 25, 461-482. 
Granger, S.J., Bol, R., Meier-Augenstein, W., Leng, M.J., Kemp, H., Heaton, T.H.E., White, S. 2010. The hydrological response of heavy clay grassland soils to rainfall in south-west England using δ2H. Rapid Communications in Mass Spectrometry, 24, 475-482.
Trofimovs, J., Fisher, J.K., Macdonald, H.A., Talling, P.J., Sparks, R.S.J., Hart, M.B., Smart, C.W., Boudon, G., Deplus, C., Komorowski, J, C., Le Friant, A., Moreton, S.G., Leng, M.J. 2010. Evidence for carbonate platform failure during rapid sea-level rise; ca 14 000 year old bioclastic flow deposits in the Lesser Antilles. Sedimentology, 57, 735-759. 
