- URLSzulc, A., Bernard, T., Johnson, C., Carter, A., Gallagher, K., Kinnaird, T.C., Steer, P., Whitham, A.: The Thermal History of East Greenland – Insights From Regional Apatite Fission Track and (U-Th)/He Data. AAPG:SEG International conference & Exhibition, ExCeL, London (2017).
- Abstract URLSanderson, D.C.W., Cresswell, A.J., Kinnaird, T.C., MacKinnon, G., Donnelly, C., Olive, V., Ellam, R., Sakellariou, D., Bailey, G.: IRSL dating of fine-grained marine sediments from the Red Sea continental shelf near Farasan: dealing with signal stability, test-dose sensitisation and U mobility. 15th International conference on luminescence and electron spin resonance dating, Cape Town, South Africa (2017).Luminescence dating is an important tool for constraining sediment formation ages and post-depositional processes in many Quaternary environments. Ideally bright, stable, homogeneous, well-zeroed luminescence signals from materials with constant and readily measured dose rates would be used. However when dating material which crosses glacial cycle boundaries, in settings which have changed markedly during the periods under study, more challenging conditions may be encountered. Here we discuss marine cores from the Red Sea continental shelf near Farasan, collected as part of the DISPERSE project which concerns the environments associated with human dispersal along the Arabian coast. Luminescence profiling of two cores (FA12 and FA13) from the inner shelf suggested preservation of late Pleistocene material, currently at depths of 80-100m, overlain by finer grained holocene sediments. IRSL SARA dating was initially used to confirm this for core FA13. Here we present an extension of this work looking at management of signal stability, examining pre-dose of test dose response and its effect on SARA procedures, and evidence for uranium mobility particularly in the upper layers. Thermally stabilised SARA approaches combine prolonged external preheating prior to first measurement, with later automated readout stages using shorter preheats in an attempt to minimise short-term fading of dating signals. Fading tests over 10^5 - 10^7 s storage periods produced mean decadal fading rates (1.2-3.6%) within overall uncertainties suggesting that this may have succeeded. However, test dose responses were seen to encode pre-dose dependence, with potential to bias dose estimates and response curves. These results are discussed here together with solutions based on additional cycles of external and within-reader irradiation and heating to equalise pre-dose conditions. Both test-dose normalisation and regenerated dose normalisation then give equivalent results, and dose estimates progress stratigraphically. Dosimetry using a combination of thick source beta counting (TSBC), and high-resolution gamma spectrometry (HRGS) revealed signifiance excess uranium (up to 10-15 ppm, from sediments containing 1-2 ppm Th), on the basis of 234Th analysis and excess beta dose rates (attributed to 234Pa) when comparing TSBC and HRGS. Further characterisation using alpha spectroscopy and ICPMS has been undertaken, and used to produce time dependent dose rate models for age estimation. The outcomes provide a chronology for the marine sediments and confirm the presence of late Pleistocene material on the inner shelf.
- Abstract URLSimpson, I.A., Kinnaird, T.C., Coningham, R., Davies, C.: Can we rebuild Kasthamandap? Ensuring outstanding universal value in post-disaster environments. Inaugural International Conference: Global Challenges in Cultural Heritage, University of Stirling, Stirling (2017).Extreme short-term environmental shocks leaving disaster in their wake are a fact of life for millions across the globe. Heritage sites and monuments are often caught up in the destruction but even for sites of international value there is little planning on how to best to handle the immediate aftermath of disaster or how a post-disaster future should be developed. Absence of post-disaster planning can contribute as much damage as the environmental event itself with new and robust protocols needed for effective heritage management when disaster strikes. Nepal’s 7.8 magnitude earthquake of April 2015 caused a human catastrophe with loss of life, livelihoods and destruction within Kathmandu's unique UNESCO World Heritage Sites (WHS). These buildings were not just ornate structures but living monuments, a portal to the gods, and central to thousands of daily lives. Emergency responses to the disaster met immediate humanitarian needs but heritage rehabilitation was unilateral, limited with marginalisation of traditional stakeholders and with irreversible damage to monuments through the adoption of ‘Build Back Better’ post-disaster protocols. Our current science-based geoarchaeology programme based on the post-disaster World Heritage Kasthamandap monument is now suggesting new and conservation sensitive post-disaster heritage protocols are possible, giving new narratives of site formation and guiding future restorations. Our contributions complement and enhance archaeological investigations and include new understanding of site chronologies, achieved through the integrated application of optically stimulated luminescence and radiocarbon; new understanding of pre-monument rural and urban environments by 'reading' sediments with micromorphology, scanning electron microscopy and xrf analyses; and through analyses of sediment physical properties identifying earthquake proofing of monument foundations during earlier construction phases. In short, our work is enhancing the Outstanding Universal Value, integrity and authenticity of this site, sought in UNESCO WHS designations. Implementation of these protocols and the analyses they enable is critically dependent on engagement with local communities and stakeholders. We have developed protocols with first responder groups to ensure appropriate salvage and scientific archiving. Furthermore, we are developing local and regional post-disaster research capacity by sharing experiences, emerging best practices and protocols through interactive and site-based workshops for research-based and local community stakeholders. Our Kathmandu Valley experiences also have resonance in other parts of the South Asian region with interest from Myanmar, Sri Lankan and Indian colleagues who have faced (and will continue to face) similar extreme environmental shocks. We are also producing for capacity building purposes a geoarchaeology based 'Manual’ of heritage post-disaster protocols as a tangible output from the workshop. This will be both hard copy and web-based, and while using the Kathmandu Valley experience as our case studies, the near universal applicability of these protocols in a range of extreme shock scenarios will ensure wide reach.
- Abstract URLCarter, J., Cresswell, A.J., Kinnaird, T.C., Carmichael, L., Murphy, S., Sanderson, D.C.W.: Is something wrong with my photomultiplier? Investigating excess variations in photon counting systems used for luminescence dating and detection of irradiated foods. 15th International conference on luminescence and electron spin resonance dating, Cape Town, South Africa (2017).Photon counting has been used in TL analysis for more than 40 years, with evidence that response to light sources show conformity to Poisson statistics at least for short term variations. Recent papers however have drawn attention to excess variations in some photon counting used in more recent instruments 1,2, and have suggested that the errors estimated for luminescence dating would be underestimated if such excess variations occurred. To investigate this studies of 10 photon counting systems were conducted at SUERC examining the ratio of observed to Poisson variance at very low phosphorescence levels and for dark signals. The results indicate that while phosphorescence is normally detected with variance consistent with Poisson uncertainties some of the systems, and particularly the more modern one showed excess dark signal variations. Further examination suggested that multi-event bursts, which were more prominent in some systems than others, were associated with the majority of the excess dark count variations. Accordingly, a procedure was developed to identify and correct for such events based on retrospectively evaluating the Poisson probability of obtained the observed results. This procedure was then applied to a single grain data set from a Neolithic chambered tomb in Corsica, where significant proportions of grains gave signals which fell below significance levels based on Poisson rejection criteria. When compared the results from corrected data sets (26+-5 Gy) and the original data (25+-4 Gy) lead to similar equivalent doses, from which we conclude that the impact on age determination is modest. Nonetheless it is appropriate to characterise detection systems and to take account of excess variance in dark signals when assessing signal significance.
- Abstract URLKinnaird, T.C., Turner, S., Bolòs, J., Turner, A., Sanderson, D.C.W.: New methods for characterising historic landscapes: OSL profiling and dating of agricultural terraces and earthworks in the west and central Mediterranean. UK meeting on luminescence and ESR dating, University of Liverpool, Liverpool (2016).Dating agricultural terraces is notoriously difficult. The frequent occurrence of residual material in terrace soils and potential for post-depositional disturbance mean that artefactual and lab-based dating methods often provide conflicting evidence. Here we explore a coupled approach using luminescence field-profiling and OSL dating to elucidate soil formation and mixing processes, and contextualise individual (and associated) sediment ages. Instead of relying on single dates provided by archaeological finds or lab methods, field profiling enables the creation of a complete relative sequence for the sediments associated with a feature. This is demonstrated through a series of case-studies in western Catalonia, Spain, where sequences of earthworks from the Middle Ages through to the present day are reconstructed, and to preliminary studies in the Greek Cyclades, on Naxos and Keros. There are detailed documentary sources for Catalonia, which enable location of many field systems, and understanding of the exploitation and organisation of the medieval landscape from the 9th AD onwards (Bolòs 2004). Here terrace systems have existed from at least c. AD 1000. The Catalan landscape also exhibits a range of terrace types including check-dams, terraced fields, step terraces, braided terraces and irrigated terraces. For these reasons it provides a good region to test methods for dating terraces. In contrast, the case-studies in Naxos and Keros, rely on retrogressive analysis to place the field systems into a relative chronology (Crow et al. 2011; Turner and Crow 2010). Field- and lab-profiling provides the first quantitative means of placing these field systems and agricultural terraces into a temporal framework and providing absolute correlations. Archaeologists’ attention often remains focussed on identifying specific and spatially defined ancient ‘sites’, rather than thinking more generally in terms of wider landscape history and processes. In part, this has been because it has been difficult to date the evolution of features like terraces or field boundary banks. The case-studies presented here show that luminescence approaches are a valuable tool to re-construct landscape histories. The method has outstanding potential to deepen our understanding of the chronology of terrace systems across the Mediterranean and around the world, and thus to contribute to creating highly detailed histories of land use.
- Abstract URLAkintunde, B.O., Sanderson, D.C.W., C., K.T., Cresswell, A.J., Carmichael, L.A., Martin, L.: Calibrating gamma dose rates for palaeodosimetric dating systems: Evaluating dose rate gradients. UK meeting on luminescence and ESR dating, University of Liverpool, Liverpool (2016).In palaeodosimetric dating systems, such as luminescence and electron spin resonance dating, the cumulative effects of exposure to ionising radiation in natural materials, quantified as equivalent doses, and related to dose rates in order to determine ages. The dose rates applicable are due to alpha, beta and gamma radiation of natural decay series radionuclides, beta and gamma contributions of natural potassium and rubidium, and an additional contribution from cosmic radiation. While alpha and beta dose rate contributions originate within dating samples, gamma and cosmic contributions come from the surrounding environment and are estimated using a combination of in-situ measurements and modelling. In-situ gamma spectrometry and in-situ luminescence dosimetry are two approaches which can be used to determine dose rates in the complex stratigraphy of archaeological or environmental sites. These approaches are usually calibrated relative to reference fields of homogeneous materials with known concentrations of naturally occurring radionuclides. This poster describes work being undertaken at SUERC to characterise two new reference boxes of 1.2m x 1.2m dimension containing known quantities of rock aggregates from two Scottish Quarries. The boxes were constructed ahead of the UKLUM15 meeting in Glasgow, and working values of the dose rates within the boxes were estimated based on laboratory gamma spectrometry of 54 samples taken during filling. Two access tubes are present to facilitate instrumental or dose rate measurements, and initial simulations of the dose rate gradients in the tubes were conducted by Loic Martin using the DOSIVOX tool. These predict an asymmetric dose rate gradient across the box with central areas of constant dose rate. Here we use a combination of in-situ gamma spectrometry and luminescence dosimetry to measure the dose rate gradients within the boxes and compare the outcomes with simulated predictions.
- Abstract URLPane, S.H.A., Sanderson, D.C.W., Kinnaird, T.C., Carmichael, L.A.: Investigating feldspar compositions and kinetic responses in TL onset methods for thermal history analysis. UK meeting on luminescence and ESR dating, University of Liverpool, Liverpool (2016).Stimulated luminescence methods have recognised potential for recording thermal histories in archaeological, geological, geo-environmental and engineering applications. Yet the dependences of luminescence behaviour on specific mineral composition, and geological, radiation and thermal histories are potentially complex, and need to be monitored and compensated for by calibration procedures. Recent work on OSL and IRSL thermochronology methods have focussed on the use of isothermal decay analysis to estimate kinetic parameters, used in combination with dose response curves and fading tests to account for the partial filling of natural systems in response to their recent thermal histories (Guralnik, 2014). By contrast TL onset temperature methods utilise the properties of systems containing distributions of traps, whose least stable surviving components can be rapidly and precisely registered on the rise of a natural TL curve. The feldspar system is well suited to this approach. More recently TL onset methods have been shown to respond to geothermal temperatures in the range from 10-40°C in the 2.5 km deep Outokumpu borehole (Sanderson et al 2014), and to register thermal gradients in shallow boreholes in Scottish Granites (Mooney et al, 2014). The procedures included regenerative calibration to account for sample specific behavioural changes within variable lithology. However it was notable that the relationship between onset temperature in the natural cycle and external controls was more precisely reproduced, than the overall uncertainty following regenerative calibration. In this poster a combination of SEM characterisation and luminescence analysis is used to look at the extent to which the calibration data dispersion observed can be related to feldspar composition within the samples. The potential for improving temperature resolution of calibrated data to the 1-2 degree resolution of onset temperature measurements by selecting individual feldspar components is assessed.
- Abstract URLSanderson, D.C.W., Kinnaird, T.C.: Optically Stimulated Luminescence dating as a geochronological tool for the dating of Late Quaternary sediments in the Red Sea region. . International Workshop on 'The Red Sea, its Origin, Structure and Environment', Jeddah, Saudi Arabia (2016).Optically stimulated luminescence, and its related variants, have emerged in recent decades as important geochronometric tools for constraining sediment formation ages and post-depositional processes in many Quaternary palaeo-environments, including those of the Red Sea region. In this presentation the underlying principles and age limits of luminescence dating are outlined. Examples are discussed of work which has defined the age limits of relic dune systems in the Saudi peninsula, and studies conducted within the DISPERSE project on marine cores off the Farasan coast and on the littoral fringe of southwest Saudi Arabia. The results confirm the utility of luminescence dating to palaeo-environmental work in the Red Sea region, and testify to varied environmental conditions in the past, which make this area critical for human dispersal and occupation during the Palaeolithic. It is to be hoped that further research in coming decades will provide a dense regional chronology that can be used to define the environmental history of this important area. Luminescence dating is part of a class of radiation damage dating methods, which include electron spin resonance (ESR) dating and methods based on stimulated luminescence of minerals, by heat, as in thermoluminescence (TL), or light, as in photostimulated luminescence (PSL) or optically stimulated luminescence (OSL). In these methods prolonged exposure to ionising radiation in the physical environment deposits energy, and information, through charge-trapping at defect centres in insulating minerals. By stimulating release of such radiation induced trapped charge, using heat (TL) or light (OSL), measureable light emission occurs that can be detected and quantified using photon counting methods. The strength of luminescence signals depends on the extent of prior exposure to natural radiation since an earlier zero condition, and on the sensitivity of the individual minerals, which has a complex dependence on formation and post formation conditions. In dating techniques, a series of calibration experiments are undertaken with laboratory sources to quantify the natural luminescence signal in terms of “equivalent dose”. This corresponds to the radiation dose (in units of Grays, which are a measure of energy deposition per unit mass) which would account for the natural signals observed from the mineral system under study. In parallel with the equivalent dose determination, a combination of low-level radiometric measurements, radionuclide concentration measurements, and dosimetric modelling is used to define palaeo-dose rates from the sample and its environment. The luminescence age is then determined as the quotient of equivalent dose to palaeo-dose rate. For sediments which have (i) been effectively zeroed prior to last deposition (for example by light exposure, or by heat), (ii) which have not been subject to post-depositional alterations, (iii) whose luminescence signals are retained with stability, and (iv) whose dose response characteristics can be reconstructed in the laboratory without bias, luminescence ages correspond to the physical time interval since deposition. For systems with more complex behavior of origins, the system can deliver information on depositional and post-depositional conditions which may be of value in combination with other information to help constrain understanding of sedimentary records. The system is also capable of yielding information about past thermal histories, and of registering the effects of prolonged light exposure to lithic surfaces.
- Abstract URLRobertson, A.H.F., Kinnaird, T.C., McCay, G., Palamakumbura, R., Chen, G.: Closure of S Neotethys in the E Mediterranean region, exemplified by the tectonic development of the Kyrenia active margin/collisional lineament, N Cyprus. European Geosciences Union General Assembly (2016).Active margin processes including subduction, accretion, arc magmatism and back-arc extension play a key role in the diachronous, still incomplete closure of the S Neotethys. The S Neotethys rifted along the present-day Africa-Eurasia continental margin during Late Triassic and, after sea-floor spreading, began to close related to northward subduction during Late Cretaceous. The northern, active continental margin of the S Neotethys bordered several rifted continental fragments. The present-day convergent margin ranges from still subaqueous (e.g. Mediterranean Ridge) to subaerial and is variably obscured by microcontinent-continent collision (e.g. SE Turkey). An excellent, subaerial record of convergent margin-early stage collisional processes are exposed in the Kyrenia Range, N Cyprus; a result of strong uplift during the last ca. 2.5 Ma (Pleistocene). This likely resulted from collision of a continental promontory of N Africa (Eratosthenes Seamount) with the S Neotethyan active margin. A multi-stage convergence history is revealed by a combination of mainly field structural, sedimentological and igneous geochemical studies. Initial Late Cretaceous convergence resulted in burial metamorphism, possibly related to the collision, then rapid exhumation of a continental fragment (stage 1). During the latest Cretaceous-Palaeogene, the Kyrenia lineament was characterised by subduction-influenced magmatism and syn-tectonic deposition. Early-Mid Eocene, S-directed thrusting and folding (stage 2) was likely influenced by final closure of the Izmir-Ankara-Erzincan ocean to the north (‘N Neotethys’). Convergence continued during the Neogene, dominated by deep-water terrigenous gravity-flow accumulation. Further S-directed compression took place during Late Miocene-earliest Pliocene (stage 3) in an oblique left-lateral stress regime, probably influenced by collision of the Tauride and Arabian continents to the E. Strong uplift of the active margin took place during the Pleistocene related to incipient continental collision (stage 4), as documented by a downward-younging flight of marine and continental terrace deposits. Each of the four above main deformation stages records an interruption of relatively steady state convergence by a collisional event within the wider region, with interesting regional implications.
- Abstract URLPalamakumbura, R.N., Robertson, A.H.F., Kinnaird, T.C., van Calsteren, P., Kroon, D., Tait, J.A.: Quantitative dating of Pleistocene terrace deposits of the Kyrenia Range, northern Cyprus: implications for timing, rates of uplift and driving mechanisms in an incipient collision zone. . European Geosciences Union General Assembly. p. 17th-22nd April (2016).The Kyrenia Range is a narrow E-W trending mountain range up to c. 180 km long by up to ca. 20 km wide, which is located < 100 km south of the Anatolian orogenic plateau within the easternmost Mediterranean Sea. The Kyrenia Range structural lineament underwent tectonically driven uplift mainly during the Pleistocene in a setting dominated by incipient continental collision. The likely driver of the uplift was the collision of the Eratosthenes Seamount, an inferred promontory of northern Africa, with a subduction zone located to the south of Cyprus. To help understand the tectonic processes driving the uplift of the Kyrenia Range and how these relate to the surface uplift of other areas of the Eastern Mediterranean, several quantitative techniques have been used to date uplift-related terrace deposits exposed on the northern flank of the range. Uranium-series disequilibrium (U-series) dating provides ages of 127, 131 and 242 ka from solitary coral in shallow-marine deposits of the lowest terraces, whereas optically stimulated luminescence (OSL) dating gives ages of 53 and 76 ka from coastal aeolianite deposits. Prior to major tectonic uplift a shallow-marine carbonate setting surrounded the Kyrenia Range. Some of the youngest pre-uplift marine carbonates yielded a reversed magnetic polarity, which constrains them as older than the last palaeomagnetic reversal (0.78 Ma). The combined evidence suggests that marine environments persisted into the Early Pleistocene, prior to major surface uplift of the Kyrenia Range lineament, which appears to have climaxed in the Middle Pleistocene. The inferred uplift rates of the Kyrenia Range lineament range from >1.2 mm/yr, for the Middle Pleistocene, to <0.2 mm/yr during the Late Pleistocene. The uplift rates of the Kyrenia Range appear to be on average significantly faster than those inferred for some adjacent regions of the Eastern Mediterranean during the Pleistocene (e.g. Lebanon coast; southern Anatolian plateau margin). The new data also suggest that the Kyrenia Range was uplifted contemporaneously with the ophiolitic Troodos Massif of southern Cyprus, which is in keeping with the model of regional-scale collision of the Eratosthenes Seamount with the Cyprus trench. The uplift of the Kyrenia Range lineament took place directly adjacent to the southern margin of the much larger Anatolian orogenic plateau, which was also mostly uplifted during the Pleistocene. The timing and processes involved in the uplift of the Kyrenia Range lineament are relevant to long-term processes of continental accretion and plateau uplift. On a longer time scale, the on-going collision the Kyrenia Range can be seen as being on the way to being accreted into the larger Anatolian orogenic plateau. Terranes similar to the Kyrenia Range lineament may therefore exist embedded within the uplifted margins of orogenic plateaus in other areas of the world (e.g. southern Tibet).
- Abstract URLMooney, A., Marshall, E., Sanderson, D.C.W., Kinnaird, T.C.: Re-appraising the heat flow of Scottish granites using TL onset temperature methods. UK Luminescence and Electron Spin Resonance Dating (2015).In response to increasing demand for low carbon energy there is a global search for viable geothermal resources, resulting in reappraisal of temperature gradients of sub-surface strata. In the UK appraisals of the heat flow from radiothermal granites were conducted in the 1980’s in response to the increased oil prices of the 1970s. Recent research has suggested that failure to account fully for Pleistocene cooling may have led to systematic underestimates of the potential resource for deep geological resources in UK locations covered by the British Ice Sheet, when comparing heat flow observed in contemporary thermal gradients, with heat production rates estimated from radionuclide concentrations. Research at SUERC, based on model feldspars and samples from a deep borehole in Finland, confirmed the potential of thermoluminescence (TL) onset temperature methods to estimate thermal gradients with information recovered from signals accumulated over recent Quaternary timescales, as a new tool to re-appraise the heat production-heat flow paradox implied by these earlier geothermal assessments. In this work we have obtained granite samples from three of the original boreholes in the Grampian region in the Scottish Highlands. TL onset temperature methods have been applied to feldspar concentrates extracted from these samples, to look for thermal gradient anomalies, with potential linkage to Pleistocene cooling effects . New estimates of radionuclide contents using high resolution gamma spectrometry for comparison with the scintillation spectrometry based work of the 1980s, and to undertaken new estimates of nuclide specific heat production rates from these locations. Sixteen samples were obtained from the British Geological Survey rock store from retained core material from the Ballater, Cairngorm and Bennachie granites, at depths of approximately 90-100, 150-200 and 280-300 m. Following mineral separation, natural TL was recorded on duplicate aliquots using an SUERC TL reader and first peak half maxima temperatures determined. The data were calibrated using regenerative procedures with reheating in a laboratory furnace for 30 minutes, at temperatures from 50-250 °C, and used to determine apparent temperatures for each sample. Thermal activation energies and frequency factors for the natural and regenerated data sets were determined, and used to estimate the temporal response times for natural systems at the different borehole depths. Gamma spectrometry was conducted using 50 g ground mass samples from the same material, analysed for 40K and U, Th series using a shielded 50% GMX spectrometer, and activity concentrations determined relative to the SUERC internal Shap granite standard. Series specific heat production coefficients were used to determine the heat production for each sample. The results from Ballater show a similar profile to that obtained from the Outokumpu borehole in Finland and may be consistent with Pleistocene cooling anomalies. For the Bennachie and Cairngorm granites more complex thermal profiles were observed, with a thermal deficit at 150-200m, which appears to correspond with previously unreported U series anomalies in the radioactivity profiles. These results add significant new information to the discussion of the heat flow anomaly of these granites, but also suggest that hydrological processes may need to be considered further alongside Pleistocene cooling to account for the radiometric and luminescence anomalies.
- Abstract URLDodds, L., Carmichael, L., Sanderson, D.C.W., Kinnaird, T.C., Hamiliton, K.: Investigating thermoluminescence and photostimulated luminescence as tools in food authentication. UK Luminescence and Electron Spin Resonance Dating (2015).Luminescence has been used extensively since its discovery in the late 17th century for a wide variety of different identification techniques ranging from mineral dating methods, to irradiated food detection and antique authentication. As food authenticity has become an increasing issue this investigation was designed in order to explore the use of thermoluminescence (TL) and photostimulated luminescence (PSL) as a method of food authentication by identifying provenance information. Shellfish products, in particular razor clams, were examined as this product is exported globally and is of high value to the Scottish food industry. A preliminary study was carried out on an archive of more than 16000 TL data files, which included both natural and 1kGy irradiated data sets. The study showed significant promise in the global location discrimination of shrimp and prawn samples. This then lead to the experimental study of razor clams, sourced from 3 locations across Scotland, using both TL and PSL techniques. Variation was demonstrated on this local scale using first peak half maximum analysis of TL data and it was also shown that sufficient minerals could be extracted from the razor clams in order to measure PSL in the blue optical (470nm) and infrared (880nm) stimulation wavelength ranges. In particular it was shown in this study that samples sourced from the Outer Hebrides varied more significantly than those sourced from Orkney and East Lothian. Finally it was concluded from this analysis that luminescence does in fact show significant location discrimination potential and with further development could potentially be used in food authentication.
- Abstract URLHamilton, K., Carmichael, L., Sanderson, D.C.W., Meehan, E., Paling, S., Cresswell, A., Kinnaird, T.C., Dodds, L.: Investigating the use of low level gamma spectrometry in studies of food authenticity. UK Luminescence and Electron Spin Resonance Dating (2015).Gamma spectrometry is a well-established and frequently used technique in the identification and quantification of radionuclides, mainly in the areas of nuclear physics, geochemical investigations and astrophysics. The area of food authentication has become more prominent with consumers becoming increasingly aware and taking an interest in where their food originates. This investigation focuses on transferring low level gamma spectrometry into the area of food provenance and authentication, by looking at spectra produced from lamb samples of known origin. Analysis was carried out using a shielded 50% relative efficiency GMX detector in the Scottish Universities Environmental Research Centre on 16 samples of lamb meat to determine whether there were measurable quantities of radionuclides present, and if so whether the activity concentrations were specific to geographical location. Of these samples 14 were from known locations across Scotland and one each from New Zealand and Chile. Gamma rays from the natural series of uranium and thorium along with potassium and anthropogenic radionuclides were studied. From t radionuclides Potassium 40 & Caesium 137, could be detected reasonably well. These radionuclides were shown to have some potential in giving indications of geographical information. However the radionuclides, from the both the thorium & uranium decay chains, were harder to measure as the activity concentrations in the samples were at or beneath detection limit for the surface detector. To improve detection conditions comparative measurements were made with a LoAx Germanium detector operated in the Boulby Underground Laboratory. Detection limits at Boulby of approximately 250 mBq kg-1 were obtained in this work, which compare favourably with the surface measurements at SUERC with detection limits of 450 mBq kg-1. In both cases the results show that radiocaesium activity concentrations in lamb meat have promising regional variations within Scotland, relating to rainfall and past fallout deposition histories, and that the two imported samples can be distinguished from the locally produced lamb. Potassium 40 is readily detected but conveys information about lean mass content of meat rather than provenance. Further work is needed to improve measurements conditions to establish whether natural series activity may add useful provenance information.
- URLKinnaird, T.C., Sanderson, D.C.W., Dawson, T.: Defining the chronostratigraphy of a prehistoric settlement mound: luminescence profiling and dating at Baile Sear. 21st Annual Meeting of the EAA (2015).
- Abstract URLSanderson, D.C.W., Kinnaird, T.C., Leandri, F., Leandri, L., Casanova, M.: OSL dating of megalithic monuments at Capu di Lugu, Belvédère-Campomoro, SW Corsica. UK Luminescence and Electron Spin Resonance Dating (2015).Corsica has rich and diverse archaeological landscapes including the remarkable Statue Menhirs, considered as emblematic adaptions from megalithism in a Mediterranean island setting. Megalithic monuments are numerous on the island, the relationship between the Corsican and other European examples relating to important questions of cultural contact and innovation in prehistory. Chronology is central to research frameworks within which the evolution and dynamics of island culture can be related to the European assemblage. Yet dating is problematic, depending largely on material with indirect associations with the critical stages of construction, modification, and disuse of the monuments and their environments. Further development of methods to date lithic monuments is needed, as is modern work to tie them to the chronologies of associated cultural landscapes and palaeo-environments. In this paper we present OSL investigations associated with archaeological intervention by the Regional Archaeological Service of Corsica (DRAC) at Capu di Lugu. Excavations were carried out in May 2014 at the Stantare Menhir and Tolla 2, a nearby chambered tomb. Both sites have been affected by past agricultural activities, and face further disruption with the resumption of upland pasturing. DRAC are therefore working closely with the proprietor to document surviving features and develop managed solutions to record and conserve archaeological elements in the landscape. Critical questions for the work reported here, were to assess whether OSL profiling could identify undisturbed sediments with clear associations to constructional features, which could be used for dating. Real-time profiling was used to map the luminescence chrono-stratigraphy of sediments associated with the principal stones on both sites. Some 92 samples were investigated in the field, from 10 sedimentary sequences. This was followed by laboratory characterisation of 33 selected sediments, and OSL dating of 5 samples. The profiling results can distinguish the natural stratigraphy of the immediate surroundings of the Stantare site from archaeological deposits in the stone socket, and revealed the gradations of luminescence intensity within it. The laboratory profiles however confirmed that the combination of modern root disturbance, and residual signals from degraded clasts in the fill, so far prohibit accurate dating of the Menhir setting. At the Tolla 2 site profiling data successfully identified a set of undisturbed sediments in key association to the principal end slab of the tomb. OSL dates were however obtained from sediments beneath the slab, which fall into the archaeological period. The youngest two imply a constructional date of 2870+-190 BC. We believe that these are the first successful OSL dates for construction of a major Megalithic monument in Corsica. Considering the results obtained on a degraded site such as Capu di Lugu, the method has potential for application elsewhere.
- Abstract URLPalamakumbura, R., Robertson, A.H.F., Kinnaird, T.C., Sanderson, D.C.W.: Post-IR IRSL dating of carbonate aeolianite deposits to constrain tectonic and sea-level controls on terrace formation processes in northern Cyprus. UK Luminescence and Electron Spin Resonance Dating (2015).The Kyrenia Range, northern Cyprus is an east-west trending mountain range, which formed due to major tectonic uplift during the Middle to Late Pleistocene. Luminescence dating is used to unravel the tectonic and sea-level processes affecting the mountain range during the Late Pleistocene. The tectonic uplift resulted in a series of stepped terraces on the flanks of the mountain range. This study focuses on the youngest of all the Pleistocene terraces, locally known as the Koupia terrace. The Koupia terrace comprises patchy deposits of lithified carbonate aeolianite along the northern coast of Cyprus. Initial field profiling was carried out on the Koupia terrace deposits (Palamakumbura et al., 2015) to asses their luminescence characteristics and aid with sedimentary interpretations. Laboratory profiling was undertaken on two sedimentary sections to accurately constrain how the luminescence characteristics vary within each section to improve the accuracy of dating. Dating samples were taken from the base of the terrace deposits with lowest scatter of stored doses and sensitivities. Dose rates were calculated from eight samples collected from around the two dating samples. A combination of field gamma spectrometry, high-resolution gamma spectrometry (HRGS) and thick source beta counting (TSBC) were used to calculate dose rates. Wet gamma dose rates of 0.4 to 0.7 mGya-1 were deduced in the laboratory, which is comparable to field measurements of 0.4 to 0.5 mGya-1 (Palamakumbura et al., 2015). OSL dating was initial attempted on quartz however, the quartz proved to have low intensities, low sensitivity and a lack of thermal stability of the fast component. Therefore, the quartz system was not used for dating; focus was therefore shifted on to the feldspar system for dating. IRSL and post-IR IRSL analysis was carried out on 16 aliquots of K feldspar per sample using single aliquot regenerative (SAR) protocols. The stored dose estimates from IRSL and post-IR IRSL produced a large scatter of values, which is attributed to the sedimentary history of the deposit, which resulted in mixed age grains. Fading tests were carried out over 106 seconds, giving ratios of 0.93 ± 0.06 and 1.08 ± 0.08, for IRSL and post-IR IRSL, respectively. Finally, ages were calculated with standard microdosimetric models providing two ages of 76.1 ± 3.5 ka and 58.7 ± 2.6 ka. The final ages show that the carbonate aeolianite deposits of the Koupia terrace formed during the most recent glacial stage during a global sea-level minimum. These deposits are interpreted as representing arid climatic conditions during a glacial stage in northern Cyprus, with ongoing tectonic uplift during the Late Pleistocene.
- URLPalamakumbura, R.N., Robertson, A.H.F., Kroon, D., Kinnaird, T.C.: Plio-Pleistocene tectonic uplift the Kyrenia Range, northern Cyprus, in its regional Eastern Mediterranean setting. Tectonics Study Group Annual Meeting (2015).
- Abstract URLRobertson, A.H.F., Kinnaird, T.C., McCay, G., Palamakumura, R., Taslı, K.: Synthesis of Late Cretaceous-Quaternary tectonic, sedimentary and magmatic processes and basin formation related to episodic subduction-collision in the easternmost Mediterranean region. European Geosciences Union General Assembly 2015 (2015).Mesozoic oceanic crust of the easternmost Mediterranean has experienced northwards subduction during Late Cretaceous-Cenozoic, either continuously or discontinuously based on kinematic evidence. Much of the existing information on sedimentation within the easternmost Mediterranean oceanic basin comes from the non-emplaced continental margins of the Levant and North Africa. In addition, sedimentary basins related to plate convergence are recorded along the northern margin of the Southern Neotethyan ocean, mainly in the Kyrenia Range of northern Cyprus and its extension into the Misis Mountains of southern Turkey, coupled with the adjacent submerged areas. In a setting of only incipient continental collision such as the easternmost Mediterranean the sedimentary basins would be expected to remain entirely submarine. In contrast, the Kyrenia Range has been strongly uplifted and subaerially exposed during Late Pliocene-Quaternary time. This allows the recognition of a number of discrete phases of sedimentary basin formation: 1. Late Cretaceous (Campanian-Maastrichtian): silicic volcanism to create a subaqueous volcaniclastic apron; 2. Maastrichtian-Paleocene: pelagic carbonate deposition interspersed with proximal gravity flows and within-plate type alkaline volcanics; 3. Early Eocene: large-scale sedimentary melange (olistostrome) emplacement; 4. Late Eocene-Late Miocene: terrigenous gravity-flow deposition in a deep-water fault dissected ‘fore arc’ setting. Initial, Late Eocene non-marine coarse clastic alluvial fan deposition was succeeded by Oligocene-Miocene deep-marine siliciclastic gravity flow deposits, fining and shallowing upwards during the Late Miocene; 5. Messinian: localised precipitation of evaporites in small fault-controlled basins; 6. Pliocene: shallow-marine siliciclastic-carbonate deposition in a shelf-depth, overall regressive setting; 7. Latest Pliocene to mid-Pleistocene: gravitational accumulation of coarse talus along a strongly uplifting subaerial lineament; 8. Mid-Late Quaternary: gradual tectonic uplift giving rise to a flight of shallow marine to non-marine terrace deposits, that were also influenced by eustatic sea-level fluctuations and climatic change. The stages of basin development were punctuated by four main episodes of compression/uplift. A. Late Miocene underthrusting/metamorphism/ exhumation; B. Mid-Eocene southwards thrusting; C. Late Miocene southward thrusting/left-lateral transpression; D. Late Pliocene-Mid Quaternary tectonic uplift. In a setting of continuing plate convergence why did the nature of sedimentation change so dramatically through time? The deformation front between the Kyrenia Range and the Troodos Massif is delineated by the Ovgos Fault which shows an episodic development including Late Miocene compression (transpression) and Quaternary left-lateral strike slip. The Late Cretaceous volcanogenic rocks relate to a phase of regional arc magmatism also documented in SE Turkey. Subduction appears to have slowed or ceased during the Maastrichtian-Palaeocene while the active margin experienced extension or transtension. Following final closure of a Tethyan oceanic basin further north (‘northern Neotethys’) subduction appears to have relocated southwards and re-activated/accelerated during the Early Eocene triggering large-scale collapse of the over-riding plate and olistostrome formation. Diachronous continental collision was in progress during Early Miocene causing strong uplift of the over-riding plate, intense erosion and voluminous siliciclastic sediment supply to a fore-arc type basin in the N Cyprus-Misis area (becoming foreland basin further east, in SE Turkey). The Pliocene was characterised by eastward ‘tectonic escape’ of the Anatolian plate towards the Aegean and this allowed relatively fine-grained deposition to accumulate along the former convergent continental margin in northern Cyprus and adjacent areas (e.g. Mesaoria basin). The dramatic late Pliocene to mid-Quaternary uplift of the Kyrenia-Misis lineament, plus the Troodos massif to the south, can be explained by regional-scale collision of the Eratosthenes Seamount with the Cyprus trench to the south in a setting, more broadly, of slab rupture or break-off. The summary and synthesis given here is based on a combination of field mapping, structural, sedimentological and biostratigraphical studies, in the light of knowledge of the wider Eastern Mediterranean and Anatolian regions.
- Abstract URLSanderson, D.C.W., Murphy, S., Kinnaird, T.C., Tait, A.: Developments and applications of the SUERC portable OSL reader. UK Luminescence and Electron Spin Resonance Dating (2015).Portable OSL readers were first developed at SUERC in 2005 ahead of fieldwork examining tsunami deposits in SE Asia, and have subsequently undergone an evolution and development both in terms of instrumentation and in fields of application. Whereas the initial reader used continuous wave stimulation only, the introduction in the second generation instruments of the pulsed PSL stimulation board originally developed for detection of irradiated foods, opened the way to both CW and pulsed synchronous detection. Sequence software developed in 2009 provided access to pulsed modes as well as to CW, and to versatility in developing complex measurement sequences for multi-wavelength stimulation and bleaching. Meanwhile the hardware evolution has continued, with significant weight reductions within the original two box configuration, and new systems now produced to a one box design which removes signal and cable connection between the detector head and the control unit, and provides for a developmental environment for further enhancements. Systems have been supplied to a number of user groups working in geoscience and archaeology, who have engaged in a diverse range of application work, the majority of which continues to use CW stimulation. The original recognition that OSL intensities combine age proxy information with co-factors relating to sediment origin, brightness and dose rate holds up. The use of depletion indices as proxies for optical attenuation properties and initial residual conditions is also useful for field interpretation. Stratigraphically significant variations in post-stimulation phosphorescence (PSP) and IRSL/OSL ratios have been observed, and can be potentially useful to field interpretation of data. At SUERC the use of portable OSL profiling has become routine practice in dating applications and sampling in geoscience and archaeology – with more than 30 case studies to date in marine and terrestrial contexts. Discontinuities, erosional contacts, and inversions have been seen and recognized using field profiling, and it has proved helpful in both sample positioning and in interpreting sedimentary sequences. Where sedimentary systems have been well characterized, which increasingly involves luminescence profiling, it is also possible to use rapid OSL screening measurements to map, classify and interpret sediment stratigraphies. The poster illustrates some recent applications of the systems. They are also useful for teaching, and have potential for dosimetry applications.
- Abstract URLCastillo, M., Muñoz-Salinas, E., Sanderson, D.C.W., Kinnaird, T.C., Ferrari, L., Arce, J.L., Cruz-Zaragoza, E.: Using OSL for interpreting sediment transport processes: From mountain rivers of the Jalisco Block to alluvial deposits at the Usumacinta-Grijalva River Basin (Mexico). UK Luminescence and Electron Spin Resonance Dating (2015).The OSL has been proved to be a powerful tool for dating and obtaining information about the processes involved in sediment transport at different types of fluvial settings. In this oral paper we present the main results of two researches carried out at different sedimentary fluvial environments. The OSL is used in both studies to evaluate the grade of resetting of the mineral grains transported by rivers. In our two study areas we observe that the mineral grains are poorly reset, in these cases the inherited signals are useful to elucidate the mechanisms that drive the erosion of the landscape. The first case of study corresponds to the Jalisco Block, which is a tectonically active landscape located in the west of Mexico. There, rivers flowing to the Pacific coast deliver large amounts of sediment from the highlands to the floodplains. We observed that in the most tectonically active areas of the Jalisco Block the sediment mobilized in the channels have higher values of luminesce compared to areas with mild tectonic activity. Our second case of study is located along the floodplain of the Usumacinta and Grijalva River Basin, which is composed by alluvial deposits resulting from the denudation of mild tectonically active mountain ranges. In this case the sequences of recent flood deposits, evaluated by means of vertical sediment profiles, provided information about the source of the sediment. Our results also suggest that the erosion and sediment accumulation in the landscape is likely to be controlled by the activity of cyclones, which trigger hyper-concentrated flows that leave horizons with poorly rested sediments along the floodplain.
- Abstract URLSimpson, I.A., Coningham, R., Manuel, M., Davis, C., Strickland, K., Acharya, K., Hyland, K., Bull, I., Kinnaird, T.C., Sanderson, D.C.W.: Reconstructing sacred landscapes from soils-based research. European Geosciences Union General Assembly 2015 (2015).From soils- and sediments- based records we reconstruct development of the sacred landscape at Lumbini UNESCO World Heritage Site in the central Nepalese Terai, the birthplace of Buddha, a world religion and now a major place of pilgrimage to its temple site. The Terai is a plain less than 100 m above sea level with incising rivers that originate in the Churia Hills and flow to the Ganges. Alluvial sediments on the Terai plain, originating as laterite soils within the hills, are characterised by a range of textural classes rich in iron oxides and manganese, with sandier sediments near water sources and finer textures near the distal ends of alluvial reaches. Our objectives are to establish a chronological framework for occupation, identify influences of alluvial environments on site occupation and determine the process of secular and sacred site formation within the World Heritage Site. A set of key stratigraphies are the basis for our analyses and are located in a palaeo-channel adjacent the temple site, within the temple site itself, and within the mound of the original Lumbini village. Optically stimulated luminescence (OSL) measurements of soils and sediments together with supporting single entity radiocarbon measurements provide robust chronological frameworks. Assessment of field properties, thin section micromorphology and organic biomarkers offer new insight into the intimate and complex relationships between natural, cultural and culturally mediated processes in landscape development. Integration of our findings allows a detailed narrative of cultural landscape development at Lumbini. The area was occupied from ca. 1,500 BC first of all by a transient community who used the area for product storage and who were subject to persistent flooding with periodic major flood events. Subsequent occupation deliberately raised a permanent village settlement above the level of flood events flooding and which had associated managed field cultivation. Village life was well established by the time of the Buddha’s birth. Dating of the early and previously unknown temple site indicates a birth date of ca. 550 BC. Reconstruction of the early temple site indicates an enclosed open space with tree cover that was further elaborated with a surrounding walkway and cover during a later phase of construction. Triterpeniod and wax ester soil biomarkers indicate that the tree cover was most likely Ficus religiosa (Pipal). The study offers the first geoarchaeological investigation of Lumbini and the implications this carries for the understanding of international heritage and its conservation.
- Abstract URLKinnaird, T.C., Robertson, A.H.F.: Structural development of the Central Kyrenia Range (north Cyprus) in its regional setting in the eastern Mediterranean. Final Symposium of the Darius Programme (2014).A detailed structural analysis of the Mesozoic–Cenozoic geological development of the central segment of the Kyrenia Range in its regional tectonic context is given here. The structural evidence comes from five structural traverses, outcrop observations, small-scale structures and related regional evidence. The majority of the structures are fault planes, of which a subordinate number exhibit slickenlines (fault plane data, n = 2688; with kinematics, n = 537). Additional kinematic data were obtained from C–S fabrics and folds. Small-scale structures in each stratigraphic unit were ‘backstripped’ to reveal relative chronology. Synthesis of the structural information indicates three phases of convergence-related deformation: (1) Late Cretaceous, associated with greenschist facies metamorphism, followed by exhumation that was probably associated with WNW–ESE to ENE–WSW-trending high-angle faulting; (2) Mid-Eocene, associated with southward thrusting, coupled with ~N–S strike-slip (transfer faulting) and oblique faulting in an overall sinistral transpressive stress regime; (3) Late Miocene-earliest Pliocene, involving southward thrusting and folding, localised back-thrusting, extensive fault reactivation and large-scale segmentation of the range. Intense uplift of the Kyrenia Range took place during the Plio-Pleistocene, possibly related to the collision of the Eratosthenes Seamount with the Cyprus trench to the south of the island. The three main convergent phases relate to stages of northward subduction and diachronous continental collision affecting the northerly, active continental margin of the Southern Neotethys.
- Abstract URLSanderson, D.C.W., Kinnaird, T.C., Turner, C., Stephesn, W.E., Kukkonen, I.T., Spencer, J.Q.: TL methods for geothermal resource evaluation: appraising onset temperature methods for recovering thermal histories. 14th International Conference on Luminescence and Electron Spin Resonance Dating (2014).Reducing dependence on carbon based energy resources remains an urgent global problem if the impacts of anthropogenic climate change are to be diminished. Both UK and Scottish Governments have targets to increase renewable energy contributions by 2020, and recognize the potential for geothermal resources. Radiothermal granites are found in Cornwall, northern England and the eastern Highlands of Scotland. However, thermal gradients recorded in the 1980’s from shallow boreholes suggested that the resource potential of the granites in SW England were greater. It has recently been suggested that this evaluation may have underestimated the potential heat flow from deeper sources in the north, as a consequence of Pleistocene cooling effects. With this in mind, work has been undertaken to explore the potential of luminescence methods to register time averaged thermal histories over the timescales of glacial cooling cycles with a view to re-examining shallow borehole samples for thermal anomalies. It complements recent interest in OSL and IRSL methods for thermochronology. Here we examine the thermoluminescence (TL) response of multitrap and distributed trap systems, both under isothermal irradiation conditions in the laboratory, and in a test case using material from the 2.5 km deep Outokumpu borehole in Finland. Previous work 1,2,3 looking at luminescence systems for assessing thermal exposures of heated archaeological materials showed that, under isothermal conditions, partial annealing of luminescence signals from prior irradiation could be systematized. The onset temperature of surviving geological thermoluminescence showed a linear dependence on temperature and a log dependence on duration of heating. Experimental firings of a simulated hearth confirmed extension of this relationship, which is attributed to a pseudo-continuum of trap depths, to non-isothermal treatments up to 105s. Approaches based on this system have been successfully applied to thermal analysis of lithic and ceramic materials in archaeological settings, and to high precision assessment of fire damaged concrete in railway tunnel fires. Here, we report a two part study. Initially work was conducted with IAEA F1 feldspar, gamma irradiated at a series of temperatures ranging from room temperature to 200°C. This confirmed that TL onset temperature maintains a simple dependence on irradiation temperature under isothermal conditions. The second part involved a series of samples at 500 m depth intervals from Outokumpu covering an environmental temperature range from 6 to 38 °C. The results confirm that TL onset temperature is a sensitive palaeothermometric indicator, with potential to extend the toolkit for geothermal resource appraisals.
- Abstract URLKinnaird, T.C., Sanderson, D.C.W., Bigelow, G.: Feldspar SARA IRSL dating of very low dose rate aeolian sediments from Sandwick South, Unst, Shetland. 14th International Conference on Luminescence and Electron Spin Resonance Dating (2014).Young sediments, with low sensitivity and low dose rates, are challenging for luminescence dating. Here, we present work on the site of Sandwick South, a Norse settlement, in which these challenges were present. Field gamma dose rates below 0.1 mGy a−1, and total dose rates of 0.4–0.5 mGy a−1, combined with expected ages of less than 1 ka, resulted in a requirement for quantitative determination of equivalent doses of 0.2–0.4 Gy. The bedrock geology of the area are metagabbros, which explain both the exceptionally low dose rates and the lack of autochthonous quartz. Luminescence profiling during fieldwork revealed stratigraphically progressive OSL and IRSL signals, indicating phases in the sediments with dating potential. While laboratory characterisation recovered some quartz, its low yields and luminescence sensitivity precluded application of quartz methods. Electron microscopy confirmed the presence of feldspars, which were separated and used for IRSL Single Aliquot Regeneration Additive (SARA) analysis. Counting times for both high resolution gamma spectrometry (HRGS) and thick source beta counting (TSBC) measurements were extended by 1 order of magnitude, resulting in overall uncertainties of <6% for these low dose rates. Dose estimates were obtained using an adapted SARA protocol, incorporating long overnight preheats before first measurement, with the aim of mitigating short-term fading effects. Using these procedures, archaeologically meaningful dates were obtained from this difficult material, which are internally consistent, coherent with stratigraphy, and concordant with the radiocarbon constraints of the associated archaeological settlement. The dates demonstrate sand accumulation in the early to mid-13th century AD and also in the 18th century AD, which are contemporary with disruptive sand movements registered in other coastal regions of the Northeast Atlantic and North Sea regions. The approaches adopted here have provided solutions to the challenging conditions of this young, insensitive material and can therefore be considered to extend the range and applicability of luminescence dating methods.
- Abstract URLJohnson, C., Gallagher, K., Carter, A., Kinnaird, T.C., Whitham, A.G., Szulc, A.: Vertical profile AFT dating in East Greenland. 14th International conference on thermochronology (2014).Following the break-up of the Caledonian orogeny, East Greenland experienced protracted rifting from the Devonian until the separation of the Jan Mayen microcontinent in the Late Eocene-Early Oligocene. The present-day continent-ocean boundary is proximal to the coast of East Greenland (Scott, 2000). Therefore, a large volume of East Greenland-derived sediment is likely to now reside in basins of hydrocarbon importance on the Norwegian conjugate margin. The Caledonian basement in East Greenland is locally cut by planation surfaces that are of uncertain age. Post-Caledonian stratigraphy includes several biostratigraphically dated unconformities. Apatite fission track dating constrains the timing of the denudation events that resulted in these surfaces and contributed abundant sediment to Mid Norway. A suite of 69 samples from 14 vertical profiles (up to 1 km thick) was taken from Devonian and Carboniferous strata and Caledonian basement across East Greenland (70-75°N). Following the method of Johnson and Gallagher (2000), data from multiple samples along individual profiles were modelled together to better constrain the cooling history of the rock columns represented by the profiles. Palaeotemperature gradients were combined with thermal conductivity data on individual samples to estimate palaeoheatflow and thereby the thickness of the missing sections. Central AFT ages range from 274 ± 13 Ma to 32 ± 3 Ma. AFT age peaks define four distinct periods of denudation at 205-176 Ma, 156-148 Ma, 107-86 Ma, and 50-20 Ma. The age peaks are spatially correlated with major Caledonian structures, implying reactivation until at least the Neogene. The results highlight the importance of a Mid-Late Permian angular unconformity that is overlain by minimal synrift sediment, and a Mid Jurassic unconformity that is overlain by abundant synrift sediment. AFT ages from two planation surfaces that cut the Caledonian basement indicate rapid denudation during the Mid Permian-Early Triassic and a second phase during the Late Cretaceous-Mid Palaeogene, which may account for the limited Cretaceous strata on Jameson Land. It is likely that other planation surfaces located variously beneath Palaeogene, Triassic, and Mid Jurassic strata also originated during the Mid-Late Permian. The most recent period of denudation followed the emplacement of flood basalts at ~58-56 Ma. The results indicate that the basalts were once widely distributed between the Blosseville Kyst and Hold with Hope. Denuded sediment volume estimates exceed the present-day accommodation space of the East Greenland margin. This provides additional evidence that much East Greenland-derived sediment now resides on the Mid Norway continental margin.
- Abstract URLSanderson, D.C.W., Cresswell, A.J., Kinnaird, T.C., Meehan, E., Paling, S.: Low energy gamma spectroscopy applied to luminescence dating: evaluating dose rate measurements in surface and deep underground laboratories. UK Luminescence and Electron Spin Resonance Dating (2013).Radioactivity and its environmental distribution are widely analysed for diverse purposes. In radioecology transfer of nuclides through the biosphere is of central interest; underpinning models for dosimetry to human and non-human species. In geosciences and environmental studies radionuclides are used to understand rates of process change in natural and anthropogenic systems. Radionuclides are also used in archaeological studies and in the analysis of authenticity and provenance of materials and products. Dating sedimentary systems is increasingly important to studies of environmental change, and to assessing the impact of human activities on the environment. In luminescence dating high resolution gamma spectrometry is used to characterize the natural decay series and with other measurements, to evaluate dose rates for age analysis. Where large samples are available this can produce percent level precision and accuracy achievable within reasonable measurement periods. However where sample size is limited, or dose rates are particularly low (for example in low potassium sands associated with Aeolian or coastal dating) the performance is background limited. Here we introduce work recently initiated between SUERC and the Boulby Underground Science Facility to explore detection limits available for low-energy gamma spectrometry in the deep underground environment, where cosmic radiation is virtually absent. Systems have been appraised in a series of surface and underground environments, with and without muon suppression, and a low energy spectrometer has been established in the Boulby laboratory to evaluate dose rate performance for small samples. The underground and muon suppressed systems have significantly lower backgrounds than systems using simple passive shielding. Dose rate determinations have been undertaken from a series of dating samples which had previously been measured at SUERC. These will be outlined together with a discussion of the remaining sources of background and the potential to reduce them further.
- Abstract URLCresswell, A.J., Sanderson, D.C.W., Kinnaird, T.C.: Gamma Dosimetry in Complex Sedimentary Sequences. UK Luminescence and Electron Spin Resonance Dating (2013).Luminescence dating practice at SUERC has, for many years, used environmental dose rates estimated from a reconciliation of field gamma spectrometry and laboratory gamma spectrometry. In some cases, gamma spectrometry surveys of wider contexts have been used to assess the homogeneity of dose rates across sites where samples may be obtained at later stages of field work. Additionally, there are circumstances where samples analysed in the laboratory are the main source of information about external dosimetry of dating material. But, where possible, in-situ gamma spectrometry is directly associated with specific dating samples in which case field derived dose rates are used preferentially where differences between sample (laboratory derived) and in-situ measurements can be attributed to dosimetric heterogeneity associated with complex stratigraphy. Also in recent years, the routine use of field and laboratory luminescence profiling has been adopted to help address sedimentary discontinuities and heterogeneity, and to guide the location of dating samples and their interpretation in complex cases. On occasions it is also desirable to use profiling measurements and samples to estimate ages or sedimentation rates at positions in between the full dating samples and their associated dosimetry. In which case, careful interpolation of dose rates provides one potential approach. The work presented here aims to improve the determination of gamma dose rates at unsampled positions within complex sequences by modelling the radiation transport from defined layers with known compositions. A Monte Carlo code developed at SUERC for mobile gamma spectrometry was validated for the full natural series and incorporates a stochastic poling scheme to allow efficient and unbiased simulation of the complete gamma line list for the natural U and Th series. This poling scheme has been applied to the GEANT package, and simulations conducted for the SUERC gamma ray spectrometry pads and exploratory simulations conducted of a complex coastal sequence from the northern isles. The overall approach will be outlined here with early results and an appraisal of potential.
- Abstract URLGibson, T., K., G., Kinnaird, T.C.: Characterizing floodplain aggradation along the North Saskatchewan river using portable optically-stimulated luminescence. 71st Annual Plains Anthropological Conference (2013).Alluvial terraces are areas that are of high archaeological potential, as they are preferred locations for human settlement while undergoing periodic influxes of sediment, contributing to site preservation, but also to erosion and artifact redistribution. This poster presents results of an exploratory study that characterizes fluctuations in floodplain activity on the lowest terrace along the North Saskatchewan river at Edmonton, Alberta, Canada. Previous research places terrace formation at 8000 years before present and artifacts within the flood sediments indicate occasional precontact occupation of the area, and historic-era activities as well. Using portable optically-stimulated luminescence measurements anchored by the known date of a Mazama eruption exhibited in the stratigraphy, we consider rate of floodplain accretion, duration of standstill 74 phases, andthe identification of erosive phases. This work underscores the relationship between human occupation and low-energy floodplain dynamics and addresses broader issues related to the application of luminescence methods to date archaeological sites in these contexts.
- Abstract URLGilliland, K., Kinnaird, T.C., Gibson, T.: Perceiving the Palaeoindian Period: Using sediment luminescence characteristics to expand understandings about the timing and nature of human occupation of the early landscape in the northwestern Lake Superior Region, Canada. Developing International Geoarchaeology (DIG) (2013).Extensive rescue excavations at eight sites along a relict shoreline in the northwestern Lake Superior region, Ontario produced hundreds of lithic artifacts in quantities rarely encountered elsewhere, making this group of sites unique in their potential to impact current understandings of the occupation history of the region. Typologically, the artifacts appear to belong to the Lakehead Complex, assumed to date to the Palaeoindian period (i.e. 8000 years before present or earlier). However, this assumption is questionable as, until recently, the Lakehead Complex has never been dated using in situ materials. To that end, a combination of optically-stimulated luminescence and AMS radiocarbon dating was undertaken to produce a chronological framework for the sites. Contrary to expectations, most of the ages produced suggest that artifact-bearing deposits date predominantly to the middle Holocene period. To assess the validity of our chronology, we undertook luminescence profiling in both field and laboratory contexts, identifying several discrete packages of sediment, including early beach deposits, a subsequent reworking phase, and early and later cultural periods. These packages have stratigraphic integrity and are laterally consistent across the landscape, indicating the reliability of our chronology and demonstrating the fundamental importance of luminescence profiling in assessing depositional characteristics prior to undertaking a program of chronometric dating.
- Abstract URLKinnaird, T.C., Sanderson, D.C.W., Cresswell, A.J., Dawson, T.: A high-resolution chronology for the construction and utilisation of a Hebridean wheelhouse at Sloc Sabhaidh, North Uist. UK Luminescence and Electron Spin Resonance Dating (2013).ield and laboratory luminescence profiling techniques, coupled with quantitative OSL SAR analysis and Bayesian assimilation methods, have been applied to sediments associated with a Hebridean wheelhouse, and its immediate environment, to define its full sequence of construction, utilisation and abandonment. The wheelhouse is situated on the site of an earlier structure, represented by occupational layers which extend beneath the monument, and by midden deposits, which surround and overlie the existing structures. The monument consists of a circular external wall, and five internal radial piers (only one half of the structure was excavated), indicating a structure spanning at least 13 m. Material associated with the earliest Iron Age occupation of the wheelhouse and preceding structure(s) are dated to the 4th to 3rd century BC. The most probable date for construction of the wheelhouse is the 1st/2nd century AD. In the monument, material dating to the earliest occupation of the wheelhouse is preserved in the northern chamber, and its associated pits (c. AD 150). There is evidence of at least one episode of extensive re-building of the wheelhouse (c. AD 750), associated with the collapse of the southern part of the external wall (c. AD 600-750). This led to a re-organisation of the interior space, the abandonment of the southern chamber (c AD 750), modification of the original piers, meaning that the structure ceased to be a wheelhouse in the conventional sense. The central chamber contains a hearth sequence, which indicates occupation of this chamber through a later phase of occupation (~ 700AD) until the Norse period (~ AD 940). The final abandonment of the site is registered by clean abandonment sands starting from the tenth century AD, consistent with abandonment in the Norse period, and with the upper occupation in the northern and central chambers. This high-resolution chronology, providing information on the changing functionality and form of the monument, and the division and representation of space within the monument, is pertinent when one considers the outstanding questions in Hebridean Iron Age archaeology. The data imply a protracted period of settlement longevity, previously unrecognised in the Hebridean Iron Age and later periods, and contradictory to the traditional perceptions of periodic occupation, and the periodic replacement of earlier structures, and instead attests to a thriving Iron Age community in North Uist.
- Abstract URLMunoz-Salinas, E., Castillo, M., Sanderson, D.C.W., Kinnaird, T.C., Cruz-Zaragoza, E.: Assessing sedimentation rates at Usumacinta and Grijalva river basin (Southern Mexico) using OSL and suspended sediment load analysis: A study from the Maya Classic Period. AGU Fall Meeting (2013).Studying sedimentation rates on floodplains is key to understanding environmental changes occurred through time in river basins. The Usumacinta and Grijalva rivers flow most of their travel through the southern part of Mexico, forming a large river basin, crossing the states of Chiapas and Tabasco. The Usumacinta-Grijalva River Basin is within the 10 major rivers of North America, having a basin area of ~112 550 km2. We use the OSL technique for dating two sediment profiles and for obtaining luminescence signals in several sediment profiles located in the streambanks of the main trunk of the Usumacinta and Grijalva rivers. We also use mean annual values of suspended sediment load spanning ~50 years to calculate the sedimentation rates. Our OSL dating results start from the 4th Century, when the Maya Civilization was at its peak during the Classic Period. Sedimentation rates show a notable increase at the end of the 19th Century. The increase of the sedimentation rates seems to be related to changes in land uses in the Sierra Madre de Chiapas and Altos de Chiapas, based on deforestation and land clearing for developing new agrarian and pastoral activities. We conclude that the major environmental change in the basin of the Usumacinta and Grijalva Rivers since the Maya Classic Period was generated since the last Century as a result of an intense anthropogenic disturbance of mountain rain forest in Chiapas.
- URLKinnaird, T.C., Sanderson, D.C.W., Ghilardi, M., Bicket, A., Vella, M.-A., Diouf, O., CEREGE, co-workers at: Geo-archaeological investigations of the Pont d’Avignon (Saint Bénézet Bridge): chronological constraints on the fluvial dynamics of the Rhône from early Medieval times. 2nd Luminescence in Archaeology Science Symposium (2012).
- Abstract URLKinnaird, T.C., Sanderson, D.C.W., Ghilardi, M., Bicket, A., Vella, M.-A., Diouf, O., CEREGE., co-workers at: Sous le Pont d'Avignon: OSL dating of sediments in the lower Rhone at Villeneuve les Avignon. UK Luminescence and Electron Spin Resonance Dating Meeting (2012).OSL investigations provide a chronological framework to reconstruct the fluvial dynamics of the Rhône River at Avignon (south France) through the late Medieval to early modern periods, and support geo-archaeological investigations of the Pont d’Avignon. Diachronic analysis of historic cartographic data has provided a relative chronology for geomorphic changes of the River Rhône, which with historical accounts of the bridge; provide a link between the construction, utilisation and abandonment of the bridge with historic flooding events. Five boreholes were drilled through the west bank of the Rhône to a depth of c. 8m, in the vicinity of Villeneuze-lés-Avignon. Detailed luminescence investigations were carried out on two cores, which contain (from top down) several metres of silty clay, interpreted as post-abandonment fills, several metres of sands, interpreted as late channel fills, and gravels at c. 7.35 m, reflecting the main fill. Initial luminescence profiling, using portable OSL equipment, was used to characterise the stratigraphy in each core. It was possible to correlate between the lithostratigraphic units identified in each core on the basis of their luminescence charac-teristics. Additionally, the field profiles indicated the parts of the cores that may be better suited for dating, and showed that similar signal levels might be expected above and beneath the main sand accumulation, suggesting a high rate of sedimentation and a relative short chronology. Laboratory analysis comprised luminescence screening measurements on 15 selected samples, to assess sensitivities and approximate stored doses, and quantitative OSL SAR analysis on 9 dating samples. The laboratory profiling results implied that the age progression above and beneath the sand accumulation was modest, reinforcing the notion that the chronology was short. The individual dates fall into the late medieval to early modern period of French history, with statistical combinations pointing to an early to mid 17th century accumulation of sediment. These dates are consistent with the interpretation that the sediment accumulation is associ-ated with destructive floods, in the period associated with the end of the Little Ice Age and the warming period that followed it. It was during this period that the Pont d’Avignon was finally destroyed and that attempts to repair the broken arches were abandoned. The OSL investigations have indicated a compelling link between historic flooding events which led to the destruction of the Pont d’Avignon and the sediment deposited in over bank deposits as these floods retreated.
- Abstract URLSanderson, D.C.W., Kinnaird, T.C., Murphy, S., Ghilardi, M., Bicket, A.: Stimulation Phosphorescence (PSP) as a luminescence profiling indicator: application to the Villeneuve-lez Avignon sediment cores. UK Luminescence and Electron Spin Resonance Dating Meeting (2012).Luminescence profiling 1-9 is increasingly used to help understand sediment evolution and guide sampling for dating. In earlier works CW mode intensities were discussed as combined proxies for age, luminescence sensitivity (including attenuation effects) and dose rate. Depletion rates encode information about sample attenuation coupled to signal inheritance, and IR/OSL ratios may also encode mineralogical information. Inversions, discontinuities, and mixed layers are frequently encountered in screening work and are usually informative. Post-stimulation phosphorescence (PSP) is further considered here, illustrated by sediment cores from the Lower Rhone. The magnitudes of PSP, following dark count subtraction, can be ex-pressed relative to prior stimulated luminescence signals, thus reducing the influence of sample sensitivity on PSP profiles. It is argued that such ratios vary in response to the coupling between deep and shallow traps within the luminescence-sensitive minerals in the samples, and are thus sensitive to diagenetic origins. The ratio IR-PSP/OSL-PSP may additionally be influenced by relative spectral absorption properties of the bulk sediments being examined. In the Rhone cores PSP intensities and their ratios show stratigraphically significant variations, which link both to sediment grain size, and to the chronology of the materials associated with LIA flood deposits.
- URLPalamakumbura, R.N., Kinnaird, T.C., Robertson, A.H.F., Sanderson, D.C.W.: Pleistocene to recent uplift of coastal terraces in Northern Cyprus constrained by OSL. UK Luminescence and Electron Spin Resonance Dating Meeting (2012).
- Abstract URLGhilardi, M., Vella, M.-A., Diouf, O., Demory, F., Sabatier-Delanghe, D., Parisot, J.-C., Hermitte, D., Mathe, P.-E., Quensnel, Y., Fluery, J., Dussouillez, P., Provansal, M., Sanderson, D., Kinnaird, T.C., Bicket, A., Hartmann-Virnich, A., Delpey, Y., Berthelot, M.: Finding the lost arches of the Medieval Bridge of Avignon (Provence, South France): A geoarchaeological approach. European Geosciences Union General Assembly (2012).This papers aims to precisely locate the medieval arches of the so called Avignon’s (Saint Bénézet) Bridge (South France) and to reconstruct the fluvial dynamics of the Rhone River from Early Medieval Times to the 19th century. Until now, just four remnant arches are still visible (near Avignon) and it is estimated that 22 arches (which represents a total length of approximately 920 meters) were built to span over one of the largest French Rivers. The late roman and early mediaeval dates of several foundation poles extracted from the river bed might suggest the existence of an earlier bridge, though it remains uncertain if any of such an earlier structure was still visible when the first mediaeval bridge was built. The mediaeval bridge was erected from 1177 until 1185 (in less than 10 years), but modified a few decades later when stone arches were erected, thus raising the road level substantially. The structure of the bridge being vulnerable, seasonal floods proved a neverending threat and cause of damage which was frequently repaired with masonry or wood. Final abandon of the edifice could be placed in the late 1660s – Early 1670s according to historical sources. Questions arose about the location of the “lost arches” and evident flood events dated back to the Little Ice Age (e.g. 1500 to 1850) could be responsible of the partial destruction of the bridge. Few archaeological, architectural, historical and palaeoenvironmental works have been undertaken in order to determine the precise shape of the Saint Bénézet Bridge at certain stages of its history. Since 2010, a joint team composed by laboratories affiliated to the French Public Research Centre (CNRS) and to Universities of Avignon and of Aix-Marseille is trying to link the different phases of constructions/destructions of the monument with the fluvial dynamics of the Rhone River for the concerned period (ANR PAVAGE). The geoarchaeological approach adopted comprises bathymetric surveys (SONAR and Acoustic camera techniques) together with geophysical prospections (Electric Resistivity Tomography and Magnetic Cartography methods) in order to reveal potential locations of arches within the modern Rhone River channels (Villeneuve Lez Avignon and Avignon’s arms) and on the Barthelasse fluvial island. In addition historical sources, such as maps, were integrated together with the acquired geophysical data in a Geographic Information System in order to identify possible remnant arches. Finally, boreholes have been drilled and later linked with the geophysical data, to reveal the alluvial litho-stratigraphy and describe the geomorphic the changes in the fluvial system. Results clearly reveal the presence of large carved stone accumulation at a regular interval in the Villeneuve-Lez-Avignon and Avignon’s branches. An interpretation concerning the shape of the Saint Bénézet Bridge, in a changing morpho-dynamic context, can be assumed and fits well with various sketches and maps established from the 16th to the 17th Centuries.
- Abstract URLKinnaird, T.C., Dixon, J.E., Peltenburg, E., Sanderson, D.C.W.: Geo-archaeological investigations at Sousikou-Laona (cyprus): placing the Chalcolithic settlement and cemeteries in a landscape context. 2nd Luminescence in Archaeology Science Symposium (2012).The Chalcolithic settlement and cemeteries of Sousikou are one of the best known sites of Erimi culture in 4th Millennium BC Cyprus, containing many unique objects and artefacts, and evidence for the manufacture of the cruciform picrolite figurines. The complex is located on a spur formed by the con-ference of the Dhiarzos and Argakin Vathin rivers in the southwest of Cyprus, with views west over the Dhiarzos to the Ktima lowlands, east to the Troodos mountains, and south to the Mediterranean Sea. In detail, the complex is dissected by a ravine, cut by the Vathyrkakas stream, which separates the settle-ment (located on an elevated spur) from the main concentration of graves (located on an elevated plat-eau to the east). Given its location, between the hilly uplands and interior of the island, and the flat low-lands, the position of the complex here is likely to reflect its environmental and spatial context. The placement of the settlement and cemeteries on opposite sides of the ravine has long intrigued the archaeologists working on this site; they have favored an interpretation in which the ravine was cut following abandonment of the site. To understand the relationship between site place-ment and geology, geomorphology and environment, the authors have undertaken a range of geomorphological investigations in the wider region. This has involved the identification and correlation of a number of regional erosion surfaces (Kinnaird et al., 2011) and channel fills (Deckers et al. 2005), and the construction of a relative chronology to unravel the incision histories of the Dhiarzos and Argakin Vathin rivers. OSL dating and magnetostratigraphic studies have provided the chronological framework to this investigation. The present-day drainage of the Dhiarzos and its tributaries was established by the late Pliocene-early Pleistocene; this ‘inital topography’ developed in response to progressive uplift of the Troodos Massif, combined with slightly lower base-levels related to eustatic sea-level. From then, through the Chalcolith-ic period, to the second century BC, material was regularly flushed through the Vathyrkakas ravine, such that no detritus associated with the settlement is preserved in the axis of the ravine, or any early channel fills. During this period, the slopes of the ravine, on which part of the settlement was located, have evolved, as witnessed by the part collapse of several structures. The earliest occupational layers in the settlement are intercalated with colluvial layers. The chalcolithic inhabitants carved hollows and pits out of the soft bedrock: hearths and plastered surfaces within these hollows attest to occupation. In this process, they de-stabilised the slopes, generating slope failures. Initial luminescence profiling, using portable OSL equipment, was used to characterize the stratigraphy through a number of profiles examining these intercalated layers. Preliminary laboratory analysis, using a simplified 2-step SAR procedure, indicated that material in all units shared similar sensitivities and stored dose estimates, attesting to a short chro-nology. Quartz SAR OSL ages provide the chronology to interpret the late incision history of the Argakin Vathyrkakas ravine. The geo-archaeological investigations have revealed how the inhabitants dealt and interacted with the geology, landscape and topography of their chosen location.
- Abstract URLMunoz-Salinas, E., Castillo, M., Cruz-Zaragoza, E., Sanderson, D.C.W., Kinnaird, T.C.: Using OSL to Unravel Sedimentation Processes at Usumacinta and Grijalva Rivers (SE Mexico). AGU Fall Meeting (2012).The Usumacinta and Grijalva rivers, flowing on the southeastern Mexico, produce the largest runoff of freshwater in Mexico. The Usumacinta and Grijalva join, close to the city of Tabasco, forming a large floodplain. Due to the high discharge, these rivers deliver large quantities of sediment every year. Floods are common during the hurricane season (between May and November) affecting in some cases the populations of the state of Tabasco and in other cases leaving households on a flood risk. In this study we analyze the sedimentation processes at the Usumacinta and Grijalva rivers to determine the flood timing and sediment delivery rates at the floodplain. We use the OSL technique to analyze the luminescence signals coming from fluvial sediments to obtain sedimentation phases and ages in order to estimate fluvial sedimentation rates. To fulfill our goal, we carried out during fieldwork sedimentary profiles at Grijalva and Usumacinta river deposits. Our results of luminescence signals indicate that the Usumacinta and Grijalva rivers exhibit a complex dynamic in the floodplain. We interpret that rivers produce the sediment incision followed by a process of sediment accretion on the margins of rivers.
- URLRobertson, A.H.F., McCay, G.A., Kinnaird, T.C., Taslı, K., Raffi, I., Kroon, D., Ellam, R.M., Morris, A., Anderson, M., Necdet, M.: Tectonic development of Southern Neotethys in the E Mediterranean: Constraints from the Kyrenia Range (North of Cyprus). European Geosciences Union General Assembly (2011).
- Abstract URLKinnaird, T.C., Sanderson, D.C.W., Bishop, P., Downie, B., Simpson, I.A.: Using deep-trap luminescence signals to overcome thermal stability limits in dating tropical environments: case studies from Tanzania and Sri Lanka. 13th International Conference on Luminescence and Electron Spin Resonance Dating (2011).Tropical environments present challenges not always experienced in routine luminescence dating work, particularly for older samples where thermal stability at elevated temperatures and saturation limits are pertinent. In this paper, we report on investigations of OSL, TL, IRSL and deep-trap signals from studies in Tanzania and Sri Lanka. We consider the stability of electron traps at a range of ambient temperatures, based on pulsed annealing of natural and regenerated luminescence signals, the impact of elevated temperatures on signal accumulation, and sensitivities to bleaching of deep-trap signals that have been used to extend age-range. The sediments in both cases come from terrestrial tropical environments: southeast Tanzania (latitude ~ 6 °S, elevation 20-30 m asml) and southwest Sri Lanka (latitude ~ 8 °N, elevation 120 m amsl). The Tanzanian study aimed to date raised beach ridges extending 10-20km inland from the coast to provide a temporal framework to interpret sea-level change and tectonic uplift. The Sri Lankan study aimed to date the first period of occupation of the Fahian-lena rock-shelter, one of the earliest sites of modern human settlement along the route of late human dispersal to south-southeast Asia. Each site presents its own set of challenges. The Tanzanian deposits date to the early Pleistocene; with several samples yielding natural quartz OSL values in excess of laboratory saturation levels. Therefore high-temperature quartz approaches and post-IR IRSL deep-trap feldspar signals were used to extend the dating range. Thermal stability analyses were conducted to assess the relationship between IRSL and post-IRSL signals from K feldspars, and to compare TT-OSL, post-OSL TL and OSL signals from quartz. It was concluded that the IRSL signals in this case lack sufficient thermal stability to register dates ≥ 50 ka in this tropical environment. Post-IR IRSL signals originate from distinct and deeper traps and can be used for dating beyond the quartz SAR limit. Similarly the TT-OSL and post-OSL TL signals from the quartz phase exhibit both higher saturation levels and greater thermal stability than OSL. In the Sri-Lankan case quartz from Fahien-lena exhibits strong systematic dependence of equivalent dose on preheating temperature. This was subsequently shown to relate to the thermal stability distribution of the contributing signal sources, leading to ambiguous age estimates using standard procedures. Trap lifetimes were modelled based on kinetic parameters obtained through pulsed annealing experiments. At ambient storage temperatures of 30-40 °C most quartz OSL signals lack sufficient thermal stability to cover the period of interest (> 40 ka). The post-OSL TL approach was utilised as a means of overcoming those limitations. In both cases, the challenges of dating older Quaternary samples from tropical environments are significantly overcome using these deep-trap approaches. While the signals are harder to reset in daylight OSL or IRSL signals, our experience in these studies confirms their utility for dating older samples from elevated temperature environments.
- URLHoey, T., Hodge, R., Sanderson, D.C.W., Kinnaird, T.C.: Using optically stimulated luminescence to ‘illuminate’ sediment transport processes. European Earth Surface Process Group Meeting (2011).
- Abstract URLHewawasam, T., Bishop, P., Kinnaird, T.C., Sanderson, D.C.W.: OSL Dating of Gem-Bearing Alluvial Sections of Sri Lanka. 13th International Conference on Luminescence and Electron Spin Resonance Dating (2011).Sri Lanka has long been known for a rich diversity of gemstones in alluvial sections in broad river valleys at the bottom of the Central Highlands, but their absolute age of deposition is hitherto unknown. The gem-bearing gravel layers, enriched in heavy minerals and quartz pebbles/cobbles, are mostly found immediately above weathered rock. Overlying sedimentary materials have marked stratigraphy, consisting of several layers of varied composition and particle size. The alluvial sections show average thicknesses of about 7m over the region, extending in some sections to 20m or more. Previous palaeontological studies have suggested that these sections are of Quaternary age. The alluvial sections were derived from high-relief areas (composed of crystalline metamorphic rocks) in the Central Highlands containing residual and colluvium covers produced by slow hill-slope erosion processes (at rates of 20-40 mm/ky as derived by cosmogenic nuclides) and subsequent fluvial processes. Also, some of the alluvial fills consist of material derived from abrupt and episodic events such as landslides and flooding in periods of intensified monsoonal activity. Hence the erosion, transportation and deposition processes responsible for the sediments reflect the region‘s environmental history. Therefore, dating the alluvial layers, and relating their sedimentation rates and compositional variation across the stratigraphy, will enhance our knowledge and understanding of the environmental history of this tropical region as well as constraining the formation age of these important gem-bearing deposits. In this study, OSL profiles were constructed for seven alluvial sections from two field campaigns in October 2010 and February 2011 in Sri Lanka, using the SUERC OSL portable reader. Twenty-one samples from two alluvial sections (Pelmadulla (7.5m thick) and Ganegama (4.7m thick)) were prepared for luminescence profiling in the laboratory, by separating the polymineral and quartz-rich fractions from small samples. Detailed dating analyses were also carried out on six tube samples, three from each section, collected from the top and middle of the alluvial fill and from the basal gem-bearing gravel layer. The SAR protocol was used to measure the luminescence in quartz grains and dose rates were calculated by beta and gamma spectrometry. Laboratory profiling of the upper alluvial fills in the Pelmadulla and Ganegama sections yield apparent stored doses of between 2 and 20 Gy. In contrast, high stored doses were measured in the basal fill and gem-bearing gravel layer, ranging from 15 to 75 Gy. This remarkable difference in stored doses implies one or more depositional breaks in the sedimentary sequence. Detailed age determinations in the gem-bearing gravel layers give ages of 10ky and 9ky for the Pelmadulla and Ganegama sections, respectively. Overlying fills from both sections produced young depositional ages of 200-600y. Thus, the gem-bearing layers at the base of the sections are evidently older, with Late Pleistocene to Early Holocene ages. The overlying fills appear to have been rapidly deposited, more recently, probably by flushing of pre-existing material through the system during intensified climatic events. Our finding of recent rapid sedimentation in the inland river basins is supported by the minimum deposition along the Southern Coast of Sri Lanka over the last 4ky, as revealed by radiocarbon studies. The presentation describes these findings, which to our knowledge, provide the first absolute chronology for these Sri Lankan gem-bearing sediments.
- Abstract URLKinnaird, T.C., Robertson, A.H.F.: Alternative tectonic models for the late Cenozoic evolution of Cyprus: New evidence from the southern part of Cyprus. Tectonics Studies Group Annual Meeting (2007).Three published tectonic models for the neotectonic setting of Cyprus currently exist i.e. (i) subduction/incipient collision, (ii) advanced collision and (iii) transpression/ restraining bend. In the first model (favoured here) a subduction zone, the ‘Cyprus Arc’, existed between the Eratosthenes Seamount and the S coast of Cyprus. Subduction was initiated in the Mid-Miocene (c. 15 Ma). Extension in the overlying plate formed sedimentary basins and was caused by retreat of the trench (‘roll-back’). The Eratosthenes Seamount then collided with the trench in the Pliocene (c. 3Ma), obstructing subduction and initiating rapid uplift of the island. In the second model, involving more advanced collision, south-verging, thick-skinned, linked imbricate thrusts (e.g. the ‘Paphos Thrust’) formed at depth near the ‘Cyprus arc’, between the Kyrenia Range to the N (the Kyrenia fold/thrust belt) and the Eratosthenes Seamount in the S. The present thrust geometry dates from the Eocene (c.45 Ma) when imbricate thrusting first began in the ‘forearc’, forming a ‘Troodos-Larnaca culmination’. In the third model, a system of left-lateral faults exists between two restraining blocks, the Kyrenia Range and the Eratosthenes Seamount, which controlled the uplift of the Troodos massif. The Neogene-recent was dominated by transpression as Cyprus was extruded westwards related to the ‘tectonic escape’ of Anatolia.
- URLKinnaird, T.C., Sanderson, D.C.W., Burbidge, C., Robertson, A.H.F., Panayides, I., Tsiolakis, E., Zomeni, Z.: Optically stimulated luminescence: A means of dating neotectonism in southern Cyprus? UK Luminescence and Electron Spin Resonance Dating Meeting (2006).
- Abstract URLKinnaird, T.C., Robertson, A.H.F.: An integrated sedimentological and magnetostratigraphic study of the Pissouri Basin: constraints on the uplift history of Cyprus? British Sedimentological Research Group Annual Meeting (2006.).An integrated sedimentological, structural and magnetostratigraphic study sheds light on the Late Pliocene-Holocene uplift history of the Troodos Massif, southern Cyprus. Plio-Quaternary marine to non-marine sedimentary rocks in the Pissouri Basin, southwest Cyprus, provide an excellent record of syn-tectonic uplift. The discrete NNW-SSE-trending extensional Pissouri basin was initiated during the Early Miocene, related to changes in regional stress patterns related to subduction and/or continental collision to the south. A possible cause of extension was relative "roll-back" of the subducting/colliding plate to the south. The Pissouri Basin experienced a transition from deep-water pelagic sediments of the Maastrichtian - L. Oligocene Lefkara Formation, to more varied shallower water, mixed carbonate and terrigenous sediments of the L. Oligocene - E. Miocene Pakhna Formation. By the latest Miocene (Messinian) the Basin existed as a shallow, fault-bounded, silled depression semi-isolated from the Mediterranean Sea to the south. A range of pre-evaporitic to evaporitic facies accumulated, including minor amounts of microbial carbonate, overlain by fine to coarse-grained and redeposited gypsum. Facies analysis indicates several periods of tectonic instability during the Messinian, associated with sediment redeposition and slumping. During the latest Miocene, small fan-deltas prograded from the fault-active basin margins into ephemeral lakes overlain by palaeosols (‘Lago Mare’ facies). The sea flooded back at the end of the Messinian, followed by deposition of marginal fan-deltas, which pass basinwards into shelf-depth marls (Nicosia Formation). These sediments are intercalated with terrigenous siltstone/sandstone turbidites, previously interpreted as the bottomsets and foresets of large marine fan-deltas. Large, intercalated lenses of bioclastic calcarenites and ophiolite-derived sandstones are interpreted as conduits for marginal shelf and terrigenous material. Soft-sediment deformation and slump structures (e.g. overturned and recumbent ductile folds) characterise the margins of these channels. The orientation of the channelling and slumping indicates a generally southward palaeo-slope towards the deep Mediterranean Sea. Higher within the Plio-Pleistocene succession, stacked micro-Gilbert-type fan-deltas (<1.77 Ma) are interbedded with Terra Rosa-type palaeosols that are interpreted as prograding fan-delta topsets. To determine timing of the uplift we have generated a magnetostratigraphy for the basin by palaeomagnetically analysing each unit of the Plio-Pleistocene basin-fill. Our results indicate that rapid uplift began in the latest Pliocene (c. 1.77 Ma), coincident with the large-scale progradation of the Gilbert-type fan-deltas. This timing of uplift is compatible with earlier results from elsewhere around the Troodos Massif (‘Mesaoria Basin’). The regional driving force of the uplift has been seen as the collision of the Eratosthenes Seamount with the Cyprus active margin to the south of Cyprus.
- Abstract URLKinnaird, T.C., Robertson, A.H.F.: Alternative models for the late Cenozoic tectonostratigraphic evolution of Cyprus: New evidence from southern Cyprus. Inaugural International Meeting of IGCP 518: Fluvial sequences as evidence for landscape and climatic evolution in the Late Cenozoic (2005).The neotectonic setting of Cyprus is controversial and several models exist including, (i) subduction/incipient collision, (ii) advanced collision and (iii) transpression. In the first model, a subduction zone, commonly referred to as the Cyprus Arc, is believed to exist between the Eratosthenes Seamount and the south coast of Cyprus. Subduction in its present setting was initiated in the Mid-Miocene (c. 15Ma). Extension in the overlying plate, forming the Polis and Mesaoria Basins, was caused by retreat of this trench. The Eratosthenes seamount is believed to have collided with the arc in the Pliocene (c. 3Ma); this obstructed subduction and initiated rapid uplift of the island. In a second interpretation, a series of south-verging, thick-skinned linked imbricate thrusts are believed to occur at depth in the forearc region of the Cyprus arc, between the Kyrenia Range in the north (i.e. the Kyrenia fold/thrust belt) and the Eratosthenes Seamount in the south (i.e. the ‘Paphos Thrust’). It is argued that the present thrust geometry was initiated in the Eocene (c.45 Ma); when imbricate thrusting developed in the forearc region, forming the ‘Troodos-Larnaka culmination’. In this model, the Mesaoria Basin evolved in the Miocene to Pliocene as a piggy-back basin. In a third hypothesis, a system of left-lateral faults are inferred between two restraining blocks; the Kyrenia Range in the north and the Eratosthenes Seamount in the south. In this model late Miocene tectonism was dominated by transpression. Cyprus is envisaged as being extruded westwards, similar to (and related to) the escape tectonics, resulting in the Anatolian Plate motion. To test these tectonic models we are currently investigating the structural and sedimentological evolution of southern Cyprus, during the Neogene-Recent. We have found that sedimentation since Late Miocene time was in structurally controlled depressions/basins, elongated NNW-SSE; consistent with a localised WSW-ENE extensional tectonic regime. Geophysical evidence (focal earthquake mechanisms, seismic tomography) suggests that collision is nowadays occurring at depth beneath Cyprus. However, at a higher structural level our data are consistent with gravity spreading outwards from the developing collision/’subduction’ zone. The argument that southern Cyprus, specifically, has been in a syn-collisional setting since the Mid-Miocene is not been supported by our studies. Evidence for this model apparently came from the appearance of Troodos ophiolite-derived conglomerates within latest Miocene non-marine facies (Lago Mare facies) in SW Cyprus. However, detailed sedimentary logging, facies analysis and geomorphological studies indicate that these conglomerates are instead terrace deposits of Early-Mid Pleistocene age (when by general agreement collision-related uplift was taking place). Other reported evidence for the ‘collisional’ models is inferred compression-related thrusting in SW Cyprus (i.e. “Paphos thrust’). However, this deformation could also relate to high-level extensional gravity tectonics. Our present view is that southern Cyprus continues to undergo WNW-ENE extension related to the southwest-ward retreat of the Cyprus active margin in a regional setting of incipient continental collision.
- Abstract URLKinnaird, T.C., Robertson, A.H.F., Panayides, I.: Later Tertiary tectonic and sedimentary response to subduction and diachronous continental collision in southern Cyprus. International Symposium on the Geodynamics of Eastern Mediterranean: Active Tectonics of the Aegean (2005).African-Anatolian collision has been accommodated through a variety of tectonic processes: subduction, “back-arc” extension, collision and strike-slip faulting. To the south of Cyprus, this collision occurs at the Cyprean Arc. The tectonic setting of Cyprus is controversial and several models exist, including; (1) subduction/incipient collision; with associated extension in the over-riding plate; (2) advanced collision; with apparent compression-related thrusting in SW Cyprus (i.e. “Paphos thrust’); and (3) transpression; with left-lateral strike-slip deformation between the Kyrenia Range in the north and the Eratosthenes Seamount in the south. To test these tectonic models we are currently investigating the structural and sedimentological evolution of southern Cyprus. The aim is to use evidence from sedimentary facies, combined with information concerning penetrative structures and also with information on syn-sedimentary structures to assess the historic- and neo- tectonic situations of Cyprus. Our interpretation is that areas to the east of Cyprus (Syria, S Turkey) were in a collisional setting from Mid-Miocene time onwards (c.20Ma). However, Cyprus remained in an oceanic embayment (Levant Sea) and subduction continued during the Pliocene. Compressional processes would have been active at depth. However, at a higher structural level southward extension (trench roll-back) was taking place. In the late Pliocene (c.3Ma), the Eratosthenes Seamount collided with the Cyprus Trench, obstructed subduction and initiated rapid uplift of the Island. Tectonic escape was permitted to the SW, as oceanic crust remained in this direction. Geophysical evidence (focal earthquake mechanisms, seismic tomography) suggests that collision is nowadays occurring at depth beneath Cyprus. However, at a higher structural level in the SW the active margin still appears to be undergoing gravity spreading outwards from the developing collision zone
- Abstract URLKinnaird, T.C., Prave, A.R., Oliver, G., Parrish, R., Horstwood, M.: A revised model for the late Meosproterozoic – early Neoproterozoic tectonostratigraphic evolution of Scotland: The Torridonian revisited. British Sedimentological Research Group Meeting (2005).The Torridonian succession of NW Scotland comprises three groups, deposited during late Mesoproterozoic to early Neoproterozoic time, the Stoer, Sleat and Torridon. Previous workers have inferred that each was formed in a rift basin and that each is internally conformable. New fieldwork and detrital zircon age data indicate that this model is incorrect. Our main findings are as follows: (1) the facies characteristics and detrital zircon data for the Sleat Group indicate that it is genetically unrelated to the Torridon Group; (2) the Sleat and Stoer Groups contain features suggestive of deposition in extension-related basins that predate the c. 1.0 Ga Grenville Orogeny; (3) the base of the Applecross–Aultbea succession of the Torridon Group is an unconformity; (4) the Applecross–Aultbea succession is most objectively interpreted as a non-marine molasse. The significance of these data is that they can be used as a constraint to test and define tectonic models for the deposition of the Torridonian succession and geological evolution of the Scottish Highlands. The view that the Torridonian rocks record deposition in a suite of long-lived rifts whereas the rest of the consanguineous Laurentian margin experienced collisional and orogenic episodes becomes equivocal and in need of reassessment, if not outright abandonment.