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Abstracts
Grün, R. (2002) ESR dose estimation on fossil tooth enamel by fitting the natural spectrum into the irradiated spectrum. Radiation Measurements 35: 87-93.
Fitting the natural, derivative ESR spectrum into the irradiated spectra has been tested as a method for the estimation of the dose value of powdered fossil tooth enamel, which is the basis of ESR dating. It was found that this method has significant advantages over traditional peak-to-peak assessments, dose versus magnetic field plots as well as deconvolution of the absorption spectrum, because it is less dependent on a range of interferences. Furthermore, the fitting procedure is computationally trivial and the dose results are not dependent on random noise. It is concluded that fitting the natural spectrum ought to provide the most reliable dose estimations for most fossil teeth which have been exposed to doses of more than 5 to 10 Gy.
Grün, R., and Ward, K. (2002) A long-term fading study for ESR intensity measurement and dose evaluation on fossil tooth enamel. Radiation Measurements 35: 269-274.
Two sets of samples, originally measured in 1989 and 1995, respectively, were re-measured in 2001 to assess long-term fading of the ESR signal in fossil tooth enamel. About half of the samples of the 1989 set showed some fading of the central ESR signal, the average intensity of the irradiated aliquots of a sample decreasing by between 3 and 10%. The resulting dose values were on average between 2 and 6% larger than the original estimates. The 1995 sample set did not contain any quantifiable fading component. We infer that there may be a fading component which saturates at relatively low intensities. However, at present we are not confident that any prescribed post-irradiation annealing procedure is capable of eliminating the unstable component without affecting any other ESR parameters.2001
Curnoe, D., Grün, R. and Thackeray, F. (2001) Direct ESR dating of a Pliocene hominid from Swartkrans. Journal of Human Evolution 40: 379-391.
One tooth fragment of a hominid, Paranthropus robustus, along with two bovid teeth from the Hanging Remnant at Swartkrans were analysed by ESR. The dating study was complicated because the samples came from a collection and their precise provenance is unknown. The environmental dose rate was reconstructed by a series of in situ gamma spectrometric measurements and elemental analyses of a series of sediment samples. Subsequent U-series isotopic analyses strongly indicated that each of the three teeth underwent significantly different uranium uptake histories, thus, rendering the assumptive early U-uptake and linear U-uptake models ineffective. ESR and U-series data were used to calculate combined, open system ages, resulting in a best estimate of 1630±160 ka. An additional model that provides the maximum possible age for open systems show that the Hanging Remnant ought be younger than 2.1 million years.
Two bovid samples from Member 2, estimated to be in the one to two million years range, yielded age estimates of between about 100 to 200 ka. Theoretical considerations do not allow for any geochemical processes to cause this severe age underestimation. We conclude that the samples are of middle to late Pleistocene age, their presence in Member 2 was either due to reworking processes or the fact that the sediments from which they were recovered are considerably younger than 1 million years.
Grün, R. (2001) Trapped Charge Dating (ESR, TL, OSL). In: M. Pollard and D. Brothwell (eds) Introduction to Archaeological Sciences: 47-62,Wiley, London.
Trapped charge dating techniques, electron spin resonance, commonly abbreviated to ESR, thermoluminescence (TL) and optically stimulated luminescence (OSL) have played a major role in the establishment of chronologies in archaeology, particularly in the pre-radiocarbon time range. In archaeological applications, ESR is mostly used for dating tooth enamel, TL for sediments and burnt flint and the latest method, OSL, for sediments. TL and ESR have been instrumental to document the early evolution of modern humans in Israel. OSL allows the age estimation of sediments that were only exposed to dim sunlight for short time periods. At present, OSL dating is not yet routinely applied in archaeological studies but one can expect that this technique will lead to a breakthrough of knowledge similar to the revolution achieved by radiocarbon dating in the 1950's and 1960's.
Grün, R. and Beaumont, P. (2001) Border Cave revisited: A revised ESR chronology. Journal of Human Evolution 40: 467-482.
In view of a decade of progress in ESR dating we have revised the ESR chronology of Border Cave. A detailed gamma ray survey in 1994 and newly calculated beta attenuation data led to total dose rate estimations that are between 0 and 30% smaller than previously estimated. Accordingly, the resulting ESR age estimates are between 0 and 30% older. The ESR dates are now in good agreement with independent age estimates, particularly 14C and amino acid racemisation. New ESR dates on of the lowermost sedimentary layers, 5 WA (white ash), indicate that the sedimentation of the sequence started around 200,000 years ago.
Grün, R., Moriarty, K. and Wells, R. (2001) ESR dating of the fossil deposits in the Naracoorte Caves, South Australia. Journal of Quaternary Science 16: 49-59.
The caves near Naracoorte, South Australia, contain one of the richest and most diverse fossil fauna assemblies on the Australian continent. Three sites were selected for ESR dating because clastic, fossiliferous sediments were sandwiched between speleothem layers. This allows independent age control by highly precise TIMS U-series dating. We find that all ESR results agree within the constraints given by the U-series dates, and allow further refinement of the age of the fauna analysed, indicating that most of the fauna in the large Victoria Cave Fossil Chamber is twice as old as previously reported.
Our dating results, spanning from 280 to 500 ka for the Fossil Chamber, Victoria Cave, to about 125 ka for the Grant Hall, Victoria Cave, and 170 to 280 ka for the Fossil Chamber, Cathedral Cave, indicate little change, if any, in the megafaunal assemblage from the early Middle to the early Late Pleistocene. This changed dramatically after the last interglacial when a large proportion of the megafauna suddenly disappeared.
Grün, R., Robertson, S. and Gordon, M. Dose evaluation on a fossil tooth using an enamel fragment as well as multiple and single powder aliquots. Ancient TL 19: 5-11.
The use of single aliquots for ESR dating of tooth enamel has the advantage that small samples can be analysed ( 5 to 30 mg), requiring less sample preparation time, and that sample inhomogeneity becomes insignificant. Single aliquots dose measurements can be carried out on powders as well as fragments. The analysis of the latter is necessary when working on valuable samples, such as fossil human teeth. Thus far, no experiments have been carried out to validate single aliquot measurements on powders nor fragments. This presents a series of experiments which imply that powders and fragments give comparable results, however, post-irradiation annealing leads to significant dose underestimations.2000
Grün, R. (2000) Methods of dose determination using ESR spectra of tooth enamel. Radiation Measurements 32: 767-772.
In recent years, doubts have been cast on the validity of the conventionally applied peak-to-peak method for dose estimation. Alternative methods are reviewed, including dose versus magnetic field plots, deconvolution using Gaussian and Lorentzian line shapes, and fitting the absorption and derivative spectra with an experimentally derived spectrum of the CO2- radical. The latter methods most probably yield the most reliable results. Conventional peak-to-peak dose estimations are closely similar. On a 2- basis, nearly all methods yield statistically indistinguishable results.
Grün, R. (2000) Electron Spin Resonance Dating. In: E. Ciliberto and G. Spoto (eds) Modern Analytical Methods in Art and Archaeology. Chemical Analyses Series 155: 641-679, Wiley, New York.
Electron spin resonance (henceforth ESR) dating was first applied by Ikeya who dated a speleothem from Akiyoshi Cave, Japan. Since then, a wide range of materials have been studied in applications in geology, geography and archaeology. ESR can be used for dating of minerals which have been precipitated, such as secondary carbonates or tooth enamel, as well as materials which have been heated in the past such as burnt flint.
In archaeology, ESR dating of tooth enamel and carbonates, such as speleothems, spring deposited travertines and shells, are of particular interest and these particular applications were recently reviewed by Grün. First ESR results on burnt flint seemed promising. However, so far it was not possible to reach the reliability that is routinely obtained by thermoluminescence. Maurer showed that it is in principle possible to obtain ESR age assessments of quartz extracted from ceramics. Unfortunately, ESR is several orders of magnitude less sensitive than thermoluminescence, thus, this ESR dating approach has not been further pursued. Most of recent ESR research focusses on dating of tooth enamel and only this application is reviewed here.
Grün, R. (2000) Dating beyond the radiocarbon barrier using U-series isotopes and trapped charges. In: D.C. Creagh and D.A. Bradley (eds), Radiation in Art and Archeometry: 472-493, Elsevier, Amsterdam.
U-series and trapped charge dating are methods that can be applied to establish chronologies well beyond the range of radiocarbon dating. This paper gives a short introduction into these methods and their potential is illustrated with the dating of the Lake Mungo 3 skeleton
Since the introduction of radiocarbon dating in the late 1940's, archaeology underwent a revolution by being able to obtain absolute chronologies. Using the most sophisticated equipment, AMS accelerators, and sample pretreatment techniques, radiocarbon is limited to the dating materials that are younger than 60,000 years and in most cases younger than 40,000 years. The theoretical basis for K/Ar (and Ar/Ar) dating was also introduced in the late 1940's and has found wide application since the mid 1960's. The method provides chronologies for most of the Earth's history, but reliable dates can only be obtained from in situ volcanic material and until recently was not suited for the timescale of less than about 200,000 years. For a long time there was a significant chronological gap for which it was difficult to obtain numerical age estimates.
The last two decades have seen the increased application of U-series as well as trapped charge dating in archaeology. These methods have made considerable impacts, for example, on our understanding of modern human evolution. They have demonstrated that modern humans lived in the Levant at about 100,000 years ago, nearly 60,000 years earlier than when they first arrived in Europe. A recent dating study showed that anatomically fully modern humans arrived in Australia at about 60,000 years.
Grün, R. and Schwarcz, H.P. (2000) Revised U-series/ESR model ages for teeth from the Hoxnian type locality. Quaternary Science Reviews 19: 1151-1154.
Re-calculation of previously published U-series/ESR age results on two teeth from Layer C of the type locality of the Hoxnian Interglaciation resulted in a mean age of 404+33-42 ka. This age indicates that the deposition of this layer took place during oxygen isotope stage 11, possibly at the boundary to stage 10.
Grün, R., Spooner, N.A., Thorne, A., Mortimer, G., Simpson, J.J., McCulloch, M.T., Taylor, L. and Curnoe, D. (2000) Age of the Lake Mungo 3 skeleton, reply to Bowler & Magee and to Gillespie & Roberts. Journal of Human Evolution 38: 733-741.
We have carried out a comprehensive ESR and U-series dating study on the Lake Mungo 3 (LM3) human skeleton. The isotopic Th/U and Pa/U ratios indicate that some minor uranium mobilisation may have occurred in the past. Taking such effects into account, the best age estimate for the human skeleton is obtained through the combination of U-series and ESR analyses yielding 62,000±6,000 years. This age is in close agreement with OSL age estimates on the sediment into which the skeleton was buried of 61,000±2,000 years. Furthermore, we obtained a U-series age of 81,000±21,000 years for the calcitic matrix that was precipitated on the bones after burial. All age results are considerably older than the previously assumed age of LM3 and demonstrate the necessity for directly dating hominid remains. We conclude that the Lake Mungo 3 burial documents the earliest known human presence on the Australian continent. The age implies that people who were skeletally within the range of the present Australian indigenous population colonised the continent during or before oxygen isotope stage 4 (57,000 to 71,000 years).
Grün, R. and Stringer, C.B. (2000) ESR and U-series analyses of dental material from Tabun C1. Journal of Human Evolution 39: 601-612.
The antiquity of the Tabun Neanderthal remains was recently reassessed when gamma spectrometric U-series analyses of bone material from the complete skeleton, C1, yielded closed system ages in the range of about 14 to 63 ka (Schwarcz et al. 1998). Unfortunately, the precise provenance of the skeleton is disputed. Although it was excavated from Layer C (Garrod and Bate 1937), Garrod thought it may have been buried from Layer B. Others speculated it might actually have derived from layer D (Trinkaus 1983, 1984). Bar-Yosef and Callander (1999) concluded from the study of hitherto unpublished notes from Garrod as well as a review of the published observations, that the skeleton was most likely excavated from Layer B. Bar-Yosef and Callander (1999) felt, however, that some lingering doubts remained (i.e. C1 could be from Layer C after all) which might be resolved by dating studies. Two independent chronologies have been established for the Tabun sequence by ESR (Grün et al. 1991) and TL (Mercier et al. 1995). Although there are some discrepancies between the ESR and TL chronologies, both imply that layers B to D are considerably older than the U-series age of C1 (Schwarcz et al. 1998). The young age and inferred Upper Palaeolithic association of C1 (Schwarcz et al. 1998) was criticised on U-series methodological (Millard and Pike 1999) as well as stratigraphical and archaeological grounds (Alperson et al. 2000).
In this study we have applied ESR dating of tooth enamel and U-series dating on dental material from C1. Our results indicate, that C1 is an old specimen, more than 100,000 years old and was most probably buried from Level B into Level C.
Robertson, S. and Grün, R. (2000) Dose determination on tooth enamel fragments from two human fossils. Radiation Measurements 32: 773-779.
The ESR dose values of two human tooth enamel fragments were measured in 10 steps with an automated goniometer. ESR spectra were deconvoluted using four Gaussian peaks. The central region of the spectra is interfered with by an additional line which yields significantly lower dose values than the central, apparently axial region. There is a strong relationship between dose and width of the deconvoluted axial peaks. We attribute this to incomplete separation between the axial and interfering peaks.
Vanhaelewyn, G., Callens, F. and Grün, R. (2000) EPR spectrum deconvolution and dose assessment of fossil tooth enamel using maximum likelihood common factor analysis. Applied Radiation and Isotopes 52: 1317-1326.
In order to determine the components which give raise to the EPR spectrum around g=2 we have applied maximum likelihood common factor analysis, MLCFA, on the EPR spectra of enamel sample 1126 which has previously been analysed by continuous wave (CW) and pulsed EPR as well as EPR microscopy. MLCFA yielded agreeing results on three sets of X-band spectra and the following components were identified: an orthorhombic component attributed to CO2-, an axial component (CO33-), as well as four isotropic components, three of which could be attributed to SO2-, a tumbling CO2- and a central line of a dimethyl radical. The X-band results were confirmed by analysis of Q-band spectra where three additional isotropic lines were found, however, these three components could not be attributed to known radicals.
The orthorhombic component was used to establish dose response curves for the assessment of the past radiation dose, DE. The results appear to be more reliable than those based on conventional peak-to-peak EPR intensity measurements or simple Gaussian deconvolution methods.
Curnoe, D., Grün, R. and Thackeray, F. (in press) Direct ESR dating of a Pliocene hominid from Swartkrans. Journal of Human Evolution. ESR dating of tooth enamel samples from Swartkrans early hominid cave site indicate this site dates to older than 2 Ma. An enamel fragment attributed to P. robustus from the Hanging Remnant of Member 1 of the Swartkrans Formation is directly dated with an experimental ESR method. The results indicate this species probably lived around 2.2±0.3 Ma.
ESR dating of bovid teeth from the Hanging Remnant suggest this unit may sample a broader temporal period than previously thought. Teeth from Member 2 are also dated and reveal the presence of reworked teeth or intrusive younger deposits in the Swartkrans Formation.
Given suitable geological conditions, including relatively low sample and sediment uranium concentrations, and good understanding of stratigraphy and sample provenance, ESR dating may provide reliable dates for Pliocene-Pleistocene hominid-bearing sites. It is also appears possible to provide reliable age estimates for individual hominids with minimal damage to important fossils. [ Ref ]
Grün, R. (in press) Electron Spin Resonance Dating. In: E. Ciliberto & G. Spoto (eds) Modern Analytical Methods in Art and Archaeology . Wiley, New York. In archaeology, electron spin resonance (ESR) dating has been applied for more than 15 years. The strength of the method lies in dating of tooth enamel beyond the range of radiocarbon dating and up to about 2 million years. In recent years, ESR dating has also been applied on fossil hominids. ESR dating of tooth enamel is reviewed in detail and examples are given to illustrate the contribution that ESR dating has made for the establishment of chronologies for human evolution. [ Ref ]
Grün, R. (submitted) Trapped Charge Dating (ESR, TL, OSL). In: M. Pollard & D. Brothwell (eds) Introduction to Archaeological Sciences. Wiley, London.
Trapped charge dating techniques, electron spin resonance, commonly abbreviated to ESR, thermoluminescence (TL) and optically stimulated luminescence (OSL) have played a major role in the establishment of chronologies in archaeology, particularly in the pre-radiocarbon time range. In archaeological applications, ESR is mostly used for dating tooth enamel, TL for sediments and burnt flint and the latest method, OSL, for sediments. TL and ESR have been instrumental to document the early evolution of modern humans in Israel (Valladas et al. 1987, Mercier et al. 1995; Grün and Stringer 1991). OSL allows the age estimation of sediments that were only exposed to dim sunlight for short time periods. At present, OSL dating is not yet routinely applied in archaeological studies but one can expect that this technique will lead to a breakthrough of knowledge similar to the revolution achieved by radiocarbon dating in the 1950's and 1960's. Recent reviews on ESR dating in archaeology were published by Rink (1997) and Grün (1997), on luminescence dating by Aitken (1997, 1998) and Roberts (1997). [ Ref ]
Grün, R., Yan, G., McCulloch, M. & Mortimer, G. (in press) Detailed mass spectrometric U-series analyses of two teeth from the archaeological site of Pech de l'Aze II: implications for uranium migration and dating. Journal of Archaeological Science.
We report Th/U ages obtained by thermal ionisation mass spectrometry of cross sections of two teeth from the archaeological site of Pech de l'Aze II. The aim of this study is to reconstruct the pathways and time dependency of uranium uptake into different constituents of the two teeth.
A previous ESR dating study of the two teeth yielded age estimates in the range of about 130,000 to 200,000 years which was in agreement with the geological assignment of Riss for layers from which the specimens were recovered. The closed system U-series ages of all analyses range from 48 to 137 ka, thus yielding age estimates which are between 30 and 90 ka too young. The apparent closed system U-series ages of the dentine and cement fractions at the top of the teeth are the oldest becoming gradually younger towards the interior of the two teeth. The difference of apparent U-series ages of dentine at the outer and inner parts of the two teeth is about 35 ka. The enamel sections show the same patterns in U-concentration and progression of apparent Th/U ages as the adjacent dentine samples, but with generally younger ages. Our results indicate that uranium migrates both from the top and the base into the dentine of the teeth and from there into the adjacent enamel. Depending on the position of the sample, significant uranium uptake appears to have taken place over many tens of thousands of years. Modelling the U-uptake histories using a parametric model shows that for the cement and dentine components uptake is intermediate between linear uptake (LU) and early uptake (EU = closed system). The enamel, although often assumed to more closely approximate a closed system, shows evidence of more recent U-uptake. These results also imply that it is not possible to use a simple, single parameter U-uptake model for all components of a given tooth neither for U-series nor ESR dating. [ Ref ]
Grün, R., Tani, A., Gurbanov, A., Koshchug, D., Williams, I. and Braun, J. (in press) A new method for the estimation of cooling and denudation rates using paramagnetic centres in quartz: A case study on the Eldzhurtinskiy Granite, Caucasus . Journal of Geophysical Research.
We present a new method for the assessment of the most recent cooling and denudation rates using paramagnetic centers in quartz measured by electron spin resonance (ESR) spectroscopy. These centers have a relatively low thermal stability. For cooling rates of 40 o and 1000 o C Myr -1 , effective closure temperatures vary between 55 o and 82 o C (Ti center) and 49 o and 64 o C (Al center), respectively. Samples were collected from two cores that were drilled into the Eldzhurtinskiy Granite, which has an emplacement age of - 2 Ma as measured by U/Pb analyses of zircons. One 1500 m core was taken from a drill hole into the dome of the granite, a second core of 4000 m from a drill hole at the base of the Baksan Valley. Our results yield cooling rates of between 160 and 250 o C Myr -1 for the upper core and between 570 o and 600 o C Myr -1 for the lower core; the corresponding denudation rates are - 2.5 (upper core) and 5.5mm a -1 (lower core). The shape of the temperature profile of the lower core indicates recent erosion. When fitting the temperature data with a two-dimensional heat-transfer model, we obtain a net denudation rate of - 10 mm a -1 and cooling rates in the range of 500 o C Myr -1 , thus confirming the cooling rates estimated by ESR. However, the ESR denudation rates underestimate the erosion rate of the Baksan Valley because the geothermal gradient is not equilibrated between the surface and the depth of the annihilation temperatures, 950 and 1800 m for the Al and Ti centers, respectively. We conclude that ESR measurements of paramagnetic centers in quartz will allow the reconstruction of landscape dynamics for the past 10-1000 kyr and that in conjunction with U/Pb, fission track, and Ar/Ar analyses it will be possible to develop dynamic models for Quaternary tectonic movements. [ Ref ]
Thorne, A., Grün, R., Mortimer, G., Spooner, N.A., Simpson, J.J., McCulloch, M.T., Taylor, L. and Curnoe, D. (1999) Australia's oldest human remains: age of the Lake Mungo 3 skeleton. Journal of Human Evolution 36: 591-612.
We have carried out a comprehensive ESR and U-series dating study on the Lake Mungo 3 (LM3) human skeleton. The isotopic Th/U and Pa/U ratios indicate that some minor uranium mobilisation may have occurred in the past. Taking such effects into account, the best age estimate for the human skeleton is obtained through the combination of U-series and ESR analyses yielding 62,000±6,000 years. This age is in close agreement with OSL age estimates on the sediment into which the skeleton was buried of 61,000±2,000 years. Furthermore, we obtained a U-series age of 81,000±21,000 years for the calcitic matrix that was precipitated on the bones after burial. All age results are considerably older than the previously assumed age of LM3 and demonstrate the necessity for directly dating hominid remains. We conclude that the Lake Mungo 3 burial documents the earliest known human presence on the Australian continent. The age implies that people who were skeletally within the range of the present Australian indigenous population colonised the continent during or before oxygen isotope stage 4 (57,000 to 71,000 years). [ Ref ]
Vanhaelewyn, G., Callens, F. and Grün, R. (in press) EPR spectrum deconvolution and dose assessment of fossil tooth enamel using maximum likelihood common factor analysis. Applied Radiation and Isotopes.
In order to determine the components which give raise to the EPR spectrum around g=2 we have applied maximum likelihood common factor analysis, MLCFA, on the EPR spectra of enamel sample 1126 which has previously been analysed by continuous wave (CW) and pulsed EPR as well as EPR microscopy. MLCFA yielded agreeing results on three sets of X-band spectra and the following components were identified: an orthorhombic component attributed to CO 2 - , an axial component (CO 3 3- ), as well as four isotropic components, three of which could be attributed to SO 2 - , a tumbling CO 2 - and a central line of a dimethyl radical. The X-band results were confirmed by analysis of Q-band spectra where three additional isotropic lines were found, however, these three components could not be attributed to known radicals.
The orthorhombic component was used to establish dose response curves for the assessment of the past radiation dose, D E . The results appear to be more reliable than those based on conventional peak-to-peak EPR intensity measurements or simple Gaussian deconvolution methods. [ Ref ]
Grün, R. (1998) Reproducibility measurements for ESR signal intensity and dose determination: high precision but doubtful accuracy. Radiation Measurements 29: 177-193.
Reproducibility measurements on fossil tooth enamel show that the intensity of the main signal can be measured with high precision (< 1%). Dose response curves based on conventional peak-to-peak measurements yield doses with errors in the range of 1 to 3.5%. The most appropriate weighting model for exponential regression is the experimentally determined variance; a model using weights inversely proportional to intensity squared also gives sensible results.
Dose versus magnetic field plots on derivative and absorption spectra yield dose values with similar high precisions. However, these plots cast doubt on the general validity of ESR dose assessments from complex ESR spectra such as fossil tooth enamel. Meaningful spectrum deconvolution is urgently required for the estimation of reliable dose values. [ Ref ]
Grün, R. (1998) Dose determination on fossil tooth enamel using spectrum deconvolution with Gaussian and Lorentzian peak shapes . Ancient TL 16: 51-55.
ESR spectrum decomposition was carried out with the commercial PeakFit program using Gaussian and Lorentzian peak shapes. The results show that there is at least one component in the ESR spectrum that yields significantly lower dose values than the central peak region which is used for conventional peak-to-peak dose determinations. Both deconvolution methods yield closely similar results to simple plateaux dose assessments, which are presently much faster to perform. [ Ref ]
Grün, R., Huang, P.H., Huang, W., McDermott, F., Stringer, C.B., Thorne, A. and Yan, G. (1998) ESR and U-series analyses of teeth from the palaeoanthropological site of Hexian, Anhui Province, China. Journal of Human Evolution 34: 555-564.
ESR and U-series analyses of teeth from the palaeoanthropological site of Hexian which contained Homo erectus remains, illustrate the limited effectiveness of stand-alone ESR and U-series age estimates on faunal materials. The problem lies in the unknown U-uptake history causing very large uncertainties in the age results of both techniques. This study demonstrates the particular strength that lies in the integration of ESR and U-series dating analyses. This allows the estimation of the U-uptake history. We obtained a combined ESR/U-series age estimate of 412±25 ka (average of six analyses on two teeth). This pinpoints the deposition of the faunal remains to the time of the transition between oxygen isotope stages 12 and 11. This is in agreement with the faunal composition which show a mixture of cold adapted northern mammals and more subtropical-tropical southern elements. The age also implies that the advanced Hexian Homo erectus occurred at a similar time as the less advanced Homo erectus specimens at Locality 1 at Zhoukoudian (LI-LIII). [ Ref ]
Radtke, U., Grün, R. & Mangini, A. (1998) The Pleistocene coral reefs of Kikai-Jima (Ryukyu Islands, Japan) and their significance for palaeo sea-level reconstructions. Ocean Research 19: 245-255
Kikai-jima is located in the northern part of the Ryukyu Islands and is the nearest island (about 80 km) to the Ryukyu Trench in the East of the island chain. The island is covered by raised Quaternary coral reef terraces (Ryukyu Group) have been formed as a veneers or patches on the bedrock. Samples of oxygen isotope stage 5e were found on the highest terrace at elevations of up to 224 m a.s.l. documenting a rapid uplift of the island. Initial dating studies promised that the coral sequence was of equal importance for palaeo sea-level reconstruction as the ones of Huon Peninsula. Subsequent investigations indicated, however, that the tectonic history of Kikai was very complex and that it was not possible to establish a clear chronostratigraphic sequence.
In view of the great potential for the establishment of an independent palaeo sea-level record further samples were collected for " -spectrometric U-series and ESR dating. Our results confirm the complexity of the reef sequence which is caused by differential tectonic activity. This prohibits any pseudo-precise palaeo sea-level reconstructions. We also conclude that sea level reconstructions based on medium precision age estimates should be abandoned altogether. [ Ref ]
Simpson, J.J. and Grün, R. (1998) Non-destructive gamma spectrometric U-series dating. Quaternary Science Reviews 18: 1009-1022.
Prehistoric hominid fossils are too valuable to be dated by destructive or even partially destructive methods. Non-destructive U-series dating by g -ray counting can therefore be a valuable method if relatively large hominid fragments, such as skulls, containing measurable amounts of uranium are available. We present a description of the method as well as some results including those obtained from a previously dated coral as well as two Australian hominid skulls (WLH 50 and Mungo 3). The dating procedure is designed to minimise systematic errors which may easily overwhelm statistical errors if care is not taken. The gamma spectrometric results are in good agreement with alpha and mass spectrometric measurements as well as independent age determinations. The results show no evidence for any uranium uptake over longer time periods. [ Ref ]
Abeyratne, M., Spooner, N., Grün, R. and Head, J. (1997) Multidating studies of Batadomba Cave, Sri Lanka. Quaternary Science Reviews 16: 243-255.
In order to explore the reliability of dating techniques and to determine which materials are most useful for the establishment of precise chronologies, 14 C, ESR, TL and OSL analyses were carried out on charcoal bones, shells and sediments from the archaeological site of Batadomba Cave, Sri Lanka. The dating techniques were complemented by Fourier transform infra-red (FTIR) spectrometry, X-ray diffraction analysis as well as scanning electron microscopy (SEM). Compared with the new and existing charcoal 14 C chronology, radiocarbon dating of shells, luminescence dating of sediments as well as ESR dating of shells provided reasonable agreement. Outliers could be explained by diagenetic alteration of the samples. ESR dating of bones seems to be fraught with many complications, but also provided some reasonable age estimates. [ Ref ]
Chen, Y., Feng, J., Gao, J., Taylor, L. and Grün, R. (1997) Observations on the micro-texture and ESR spectra of quartz from fault gouge. QuaternaryScience Reviews 16: 437-493.
We have investigated fault gouge samples from a variety of sites in eastern China with ESR, optical and scanning electron microscopy (SEM), X-ray diffraction and cathodoluminescence. The results reveal two different types of quartz, a macrocrystalline and a microcrystalline variety. The macrocrystalline samples show increasing ESR intensities of the E' centre with increasing grain size whilst the microcrystalline samples show the opposite trend. We also found that the dissolution of quartz grains and secondary quartz precipitation on the surface of the grains is significant in some samples, indicating active chemical weathering in these fault zones. The occurrence of secondary quartz has serious implications for the reliability of any dating attempt. [ Ref ]
Chen, Y., Gao, J., Feng, J., and Grün, R. (1997) Investigation of the potential use of ESR signals in quartz for palaeothermometry. Quaternary Science Reviews 16: 495-499.
In order to investigate the possible use of ESR signals for palaeothermometry, samples from three petroleum exploration drill holes in Eastern China were studied. We found that the ratio of the intensities of the natural E' signal (I 1 ) over the signal after heating at 250 o C for 60 min (I 2 ) is higher for the deeper samples which were generally exposed to higher temperatures than those of the shallower samples. This behaviour can be used for establishing the contemporary storage temperatures at least up to 100 o C. [ Ref ]
Grün, R.(1997) Electron spin resonance dating. In: R.E. Taylor & M.J. Aitken (eds) Chronometric and Allied Dating in Archaeology : 217-261, Plenum, New York.
Electron spin resonance (ESR) dating was introduced to archaeology about 15 years ago. Although the method is still in a rapid phase of development it has already demonstrated its value by providing new chronological evidence about the evolution of modern humans. ESR dating in archaeology is mainly applied to tooth enamel and tooth enamel. Both applications are described in detail. Examples are given by the critical review of ESR age estimates on tooth enamel excavated from various hominid bearing sites in Israel and speleothems from the hominid site of Petralona. [ Ref ]
Grün, R., Abeyratne, M., Head, J., Tuniz, C. and Hedges, R.E.M. (1997) AMS 14 C analysis of teeth from archaeological sites showing anomalous ESR dating results. Quaternary Science Reviews 16: 437-444.
We have carried out AMS radiocarbon analysis on two groups of samples: the first one gave reasonable ESR age estimates and the second one yielded serious age underestimations. All samples were supposedly older than 35 ka, the oldest being around 160 ka. Two pretreatment techniques were used for radiocarbon dating: acid evolution and thermal release. Heating to 600, 750 and 900 o C combined with total de-gassing at these temperatures was chosen to obtain age estimates on the organic fraction, secondary carbonates and original carbonate present in the hydroxyapatite mineral phase, respectively. All radiocarbon results present serious age underestimations. The secondary carbonate fraction gives almost modern results indicating an extremely rapid exchange of this component. Owing to this very rapid carbonate exchange it is not likely that the ESR signals used for dating are associated with the secondary carbonates. One tooth from Tabun with independent age estimates of > 150 ka was further investigated by the Oxford AMS laboratory yielding an age estimate of 1930±100 BP on the residual collagen from dentine and 18,000±160 BP on the carbonate component of the enamel bioapatite. We did not, however, find an explanation of why some samples give serious ESR underestimations whilst many others provide reasonable results. [ Ref ]
Grün, R., Huang, P.H., Wu, X., Stringer, C.B. & Thorne, A. (1997) ESR analysis of teeth from the palaeoanthropological site of Zhoukoudian, China. Journal of Human Evolution 32: 83-91.
An ESR dating study on teeth collected from layers 3, 6/7 and 10 at Locality 1, Zhoukoudian provides results that are in general agreement with an earlier multi-dating study and confirm an age range of 300 to 550 ka for the Homo erectus remains in the Peking Man Cave. Uncertainties due to U-uptake and the external gamma dose rates do not allow very precise age estimates for the respective layers. [ Ref ]
Grün, R., Kohno, H., Tani, A., Yamanaka, C., Ikeya, M. and Huang, H.P. (1997) Pulsed ESR measurements on fossil teeth. Radiation Measurements 27: 425-431.
Deconvolution of X-band spectra has shown that the signal that is used in dating studies is composed of at least three different peaks. Our measurements show that pulsed ESR can separate the axial signal from two wider peaks that are suspected of interfering with any reliable dose assessment. However, its significantly lower sensitivity prohibits the routine application of pulsed ESR in dating studies. The spin relaxation time, T 2 , of the CO 2 - centre as determined from spin echo decay curves, is in the range of about 500 to 640 ns, depending on the spin concentration. [ Ref ]
Oka, T., Grün, R., Tani, A., Yamanaka, C., Ikeya, M. and Huang, H.P. (1997) ESR microscopy of fossil teeth. Radiation Measurements 27: 331-337.
We have used thin sections of an archaeological tooth sample to obtain spatially resolved ESR spectra using a pin-hole cavity. This study presents the first ESR images of naturally generated radiation sensitive signals. The 3-D plots of the natural and irradiated samples show strong variations of the ESR intensities within the enamel layers. Owing to the relatively large scattering of the data points it has not been possible to produce 3-D dose plots. [ Ref ]
Grün, R. (1996) Errors in the dose assessment introduced by the use of the "linear part" of a saturating dose response curve. Radiation Measurements 26: 297-302.
Linear fitting is still often applied when determining past radiation dose values in luminescence and ESR dating. This approach has been justified by the apparent linearity of the dose response data and better internal consistency of the data sets when applying linear fitting compared to exponential fitting. This study demonstrates that if the dose response follows a single saturating function, linear fitting causes very large systematic uncertainties, even when applied to sections of the dose response curve that show linear regression coefficients of 1. Although under certain circumstances linear fitting can indeed provide smaller random errors (i.e. a better internal consistency) than exponential fitting, the results of this study strongly suggest abandoning linear fitting altogether. [ Ref ]
Grün, R. (1996) A Re-analysis of ESR dating results associated with the Petralona hominid. Journal of Human Evolution 30: 227-241.
Two ESR dating studies of the late 1970's and early 1980's on speleothems associated with the Petralona hominid cranium yielded age estimates of 350,000 to 700,000 years and 200,000 years, respectively. These dating results are re-assessed in view of more than a decade of progress in ESR dating. The re-assessed values are in reasonable agreement with some independent U-series results on the same material, suggesting an age of 150,000 to 250,000 years for the speleothems bracketing the cranium. [ Ref ]
Grün, R., Brink, J.S., Spooner, N.A., Taylor, L., Stringer, C.B., Franciscus, R.G. & Murray, A.S. (1996) Direct Dating of Florisbad Hominid. Nature 382: 500-501.
In 1932, hominid remains were found at the Florisbad spring, near Bloemfontein, South Africa. The specimen may well represent a direct ancestor to modern humans and its age is crucial to any reconstruction of the subsequent evolution of Homo sapiens . Previous dating attempts have failed, because the antiquity of the specimen lay beyond radiocarbon dating. We have developed a virtually non-destructive method of ESR analysis and we report here the first such dating application to an important hominid specimen, resulting in an age of 259,000±35,000 years. This result agrees with OSL age estimates of sediments bracketing the spring eye from where the hominid remains originated. ESR and OSL dating furthermore yield an age of about 120,000 years for a subsequent Middle Stone Age human occupation horizon at Florisbad. [ Ref ]
Grün, R. and Clapp, R. (1996) An automated sample changer for Bruker ESR spectrometers. Ancient TL 14: 1-5.
We have developed an automated sample changer which allows the measurement of up to 40 samples without operator attendance. It had not been possible to adapt commercially available robotic arms or auto-loaders. A performance test on enamel samples from a single tooth showed that (i) the changer worked reliably and was not an additional source of error and (ii) when using Fourier transformation to eliminate high frequency noise of the spectra, the uncertainty in the measurement of the ESR intensity was in the range of 1%. Furthermore, there was no difference in the uncertainty of an ESR measurement between aliquots that were weighed as precisely as possible to 40 mg before measurement and subsamples (ranging between about 33 and 50 mg) whose weight was used after measurement for spectrum weight normalisation. [ Ref ]
Grün, R. and Jonas, M. (1996) Plateau tests and spectrum de-convolution for ESR dose determination. Radiation Measurements 26: 621-629.
Spectrum deconvolution studies show that ESR spectra of tooth enamel at g=2.0 consists of at least 3 different peaks. Dose versus magnetic field plots can be used to identify whether these peaks result in different dose assessments. If the main axial peak, which is used in most dating studies for the determination of the past radiation dose, is interfered with by non-radiation sensitive or less stable, narrower ESR signals, the conventional peak-to-peak dose assessments may be erroneous. [ Ref ]
Grün, R. and Taylor, L. (1996) Uranium and thorium in the constituents of fossil teeth. Ancient TL 14: 21-25.
In the course of ESR dating studies we have analysed the constituents of 67 teeth from 12 archaeological sites in Australia, China and South Africa for uranium and thorium by ICP-MS. We find that there is no relationship between the uranium and thorium concentrations in either dentine or enamel and that there is also no correlation between the thorium concentrations in adjacent dentine and enamel layers. There is some relationship between the uranium concentrations of adjacent enamel and dentine layers, the U concentration in dentine being about 20 times higher than in enamel. There is also hardly any connection between uranium and thorium concentrations and time which precludes any predictions of the mode of uranium and thorium accumulation. [ Ref ]
Radtke, U., Grün, R., Omura, A. & Mangini, A. (1996) The Quaternary coral reef tracts of Hateruma (Ryukyu Islands, Japan). Quaternary International 31: 61-70.
The island of Hateruma is located at the southwestern end of the Ryukyu Island chain and covers an area of about 15 km 2 with its highest point at 59.5 m.a.s.l.. The morphology of Hateruma is characterised by an eight step staircase (I to VIII after Ota et al. 1982) most of which eroded into the previously formed coral reefs (II and IV to VIII). This study presents 100 age estimations on 43 coral samples using electron spin resonance (ESR), alpha- and mass spectrometric U-series methods. The dating results imply that the Ryukyu Limestone was predominantly formed during oxygen isotope stages 7 and 5e. Two age estimates of around 300 ka suggests an earlier reef-building period. The main problem for establishing the Quaternary history of Hateruma lies in the fact that the coral ages and the staircase morphology do not correlate. Additionally, it is difficult to distinguish autochthonous from allochthonous samples, the latter may have been relocated by tsunamis. Corals relating to substages 5a and 5c (around 75 and 105 ka, respectively) are found in the immediate vicinity of much older samples. The results of this study prove the disappointing fact that Hateruma cannot yet be used as a tool for reconstructing palaeo sea-levels. [ Ref ]
Grün, R. (1995) Semi non-destructive, single aliquot ESR dating. Ancient TL 13: 3-7.
In ESR dating of tooth enamel, the specimen is usually partly destroyed: enamel is separated from dentine, ground and about ten aliquots are produced for the establishment of the dose response curve (DRC). Furthermore, some enamel and dentine material is used for uranium analysis. This partial destruction of samples is not feasible if ESR dating is to be applied on valuable specimens, such as fossil hominids. A technique was developed that allows to measure dose values on tooth fragments. [ Ref ]
Grün, R. (1994) The kinetics of TL peaks and its effect on the dose versus temperature plot. Radiation Measurements 23: 175-194.
The central procedure in thermoluminescence (TL) dating is the determination of the radiation dose, D E , that a sample has received in its geological past. Any random or systematic errors in the assessment of D E are directly reflected in the corresponding TL age estimate. In many TL dating studies, the D E value is derived from plateaux in the dose versus temperature plot.
This study presents simulations of TL glow curves containing ideal first and second order kinetics TL peaks. The TL intensities and corresponding doses were selected to lie exactly on a single saturating exponential function. The results imply that there is a wide range of possibilities to estimate incorrect D E values from plateaux in the dose versus temperature plot, even when only first order kinetics TL peaks are involved. However, it can also be shown that the regeneration method or its refinement, the slide method, can in principle produce correct D E estimates for first and second order kinetics TL peaks. [ Ref ]
Grün, R. & Brumby, S. (1994) The assessment of errors in the past radiation doses extrapolated from ESR/TL dose response data. Radiation Measurements 23: 307-315.
We employ a method for generating dose response data artificially, in which each response is computed as the sum of a saturating exponential function and a random error. Data sets generated in this way are used to check two computing strategies, straight line conversion and the simplex procedure, and to investigate the optimal distribution of data points, and the role of the selection of correct weights for the fitting of the data sets. Additionally, three methods for error estimation are tested: the analytical expression, jackknifing and Monte Carlo simulation. Jackknifing turns out to be the least suitable technique for error estimation of ESR/TL dose response data. [ Ref ]
Grün, R. & Katzenberger-Apel, O. (1994) An alpha irradiator for ESR dating. Ancient TL 12: 35-38.
Due to the large sample size required for ESR measurements ( >= 10-20 mg), ESR alpha irradiation experiments on thin fine grain layers have rarely been reported (e.g. Yokoyama et al. 1981, Grün 1985, Mudelsee 1990). Some studies have used an accelerator to determine alpha radiation effects on speleothems (Lyons & Brennan 1989, 1991) others have experimented with 210 Po-doping (DeCanniere et al. 1986).
In order to perform alpha irradiation on thin fine grain samples, we have constructed a large 241 Am-irradiator. The irradiation chamber is constructed from a 150 mm ID stainless steel tube which is cut in two halves. The top contains the alpha source and a valve to flush the chamber with argon when not in use in order to avoid oxidation of the 241 Am-foils. The bottom half contains an adjustable plate for holding samples and the collimator. The maximum distance between the source and the samples is 100mm, the positioning can be read from a steel ruler. A side valve is used to evacuate the chamber to about 10 -3 Torr. [ Ref ]
Grün, R. & McDermott, F. (1994) Open system modelling for U-series and ESR dating of teeth. Quaternary Science Reviews 13: 121-125.
The study of the constituents of teeth, dentine and enamel, by a combination of ESR and U-series techniques offer unique constraints on the history of uranium migration into these materials. Our results imply that it is inappropriate to assume a simplified U-uptake model for neither the components of a single tooth nor for the faunal remains of a given site. However, the combination of both methods may provide a new technique for establishing reliable chronologies for archaeological/Quaternary sites of up to several hundred thousand years. [ Ref ]
Grün, R. & Packman, S.C. (1994) Observations on the kinetics involved in the TL glow curves in quartz, K-feldspar and Na-feldspar mineral separates of sediments and their significance for dating studies. Radiation Measurements 23: 317-322.
It has been shown by Grün (1994) that dose estimations using additive dose methods (including partial bleach) give random results if the glow curves contain TL peaks that do not show first order kinetics behaviour. The study was carried out on simulated TL glow curves and the question arises whether these results have any practical relevance for TL dating. [ Ref ]
