Archaeological Dose Research Articles

Applying the “pre-bleached with blue LEDs” protocol to date Umayyad mosaic tesserae by thermoluminescence

Abstract This paper deals with a Thermoluminescence (TL) study of ancient mosaic tesserae from the qasr (winter residence) of Khirbat al-Mafjar, amazing palace of the Islamic caliphs located in the plain of Jericho. In literature, works dealing with the dating of mosaic tesserae usually rely on the dosimetric properties of the microcrystalline inclusions in the silica matrix rather than on the matrix itself. On the other hand, in the last decades, commercial glasses have been demonstrated to be suitable for retrospective accidental dosimetry. In this work, we applied a protocol widely used for the mobile phones’ glasses, the so-called “pre-bleached with blue LEDs” protocol, to evaluate the archeological dose absorbed by some Khirbat al-Mafjar tesserae in order to confirm their dating based on archaeological evidence. As for commercial glasses, the TL signal from ancient tesserae presents anomalous fading and it is light sensitive. The experimental protocol circumvents these problems isolating the thermally more stable TL signal with an optical pretreatment and allowing the determination of a fading curve for each analyzed sample. Using an integrative approach, we estimated the fading correction for these tesserae and we retrieved their ages. The results are partially in agreement with those hypothesized on historical ground and show good potentialities for the dating of amorphous archaeological glassy materials.

Modeling incomplete and heterogeneous bleaching of mobile grains partially exposed to the light: Towards a new tool for single grain OSL dating of poorly bleached mortars

Dating archaeological lime mortars by single grain OSL is founded on the bleaching of grains during the mixing of lime and sand. However incomplete and heterogeneous optical zeroing of grains is often observed. In the view of evaluating reliable archaeological doses, we have developed non-standard statistical tools that describe residual dose distributions. For these purposes, a model of the bleaching process, based on simple physical assumptions leads to an exponential decreasing distribution of light exposure among sand grains. Coupling this exposure distribution with both decay of OSL grains with light exposition, which is assumed to be exponential, and dose response growth curve of OSL, chosen in our case as a single saturating exponential, distributions of residual doses are obtained. Such distributions are then added to burial dose distributions (defined as the doses absorbed by the grains since the mortar making) to simulate equivalent dose distributions of archaeological materials. A very satisfactory agreement is obtained with known age reference samples; in particular, our model leads to more accurate ages than the commonly employed Minimum Age Model. Finally, we estimate that this model, to some extent, could be generalized to other bleaching processes involving a mobility of grains as a major source of random exposure of grains to light.

Methodological study on single grain OSL dating of mortars: Comparison of five reference archaeological sites

The paper focuses on single grain OSL dating of quartz extracted from known age archaeological mortars, potentially representing a new tool for dating the construction of historical buildings. Apart from SG-OSL measurements and annual dose rate determination, the samples are systematically studied by means of optical microscopy, EDX-SEM cartography and beta autoradiography in order to evaluate the possible microdosimetric heterogeneity of each sample, arising principally from local variations of potassium content. Besides the practical aspects concerning sampling, preparation and appropriate choice of measurement conditions, the paper aims at the differences in microstructure and in elementary composition between different mortars and attempts to evaluate the impact of these aspects on the dispersion of equivalent dose distributions. Finally, archaeological doses (paleodoses) are calculated by using central age model (CAM), minimum age model (MAM) and internal-external consistency criterion (IEU). The appropriateness of these models for the exploitation of the measured SG-OSL data as well as for a hypothesis on the estimation of the input parameter needed to run these models are discussed. Three categories of mortars were identified: samples without any exploitable SG-OSL signal, samples that could have been reliably dated and poorly bleached samples affected by microdosimetric variations whose dating still remains complicated. Finally, the hypothesis on distinguishing between reliable and questionable dating results is raised and the potentials of the method for dating mortars are pointed out.

Luminescence dating studies of Yeşilova Hoyuk

Abstract Ceramic findings collected from Yeşilova Hoyuk located in Izmir were dated using the thermoluminescence dating technique. The area is of significant archaeological importance since it is the first prehistoric settlement in Izmir. Recent archeological observations suggest that human occupation of the region took place about 8500 years ago comparing to previously determined dates of 5000 years. Three samples collected from the same archaeological layer (Neolithic period) in Yeşilova Hoyuk were dated using the thermoluminescence method. Archaeological doses (AD) were obtained by single aliquot regenerative dose method (SAR) for thermoluminescence (TL) using coarse grain quartz minerals extracted from samples. Thick and thin Al2O3:C thermoluminescence dosimeters (TLD) were used to determine the annual dose rate. The archaeological doses were found to vary from 25.91±0.78 to 26.82±0.68 Gy, and the annual doses were found to be between 3.34±0.24 and 3.47±0.24 mGy/a. The ages obtained for the samples were determined to be 6000±830 BC, 5740±670 BC and 5460±740 years for samples ND1, ND2 and ND3, respectively, which supports the prediction of archeologist that the sampling layer dates from the Neolithic period.

ESR dating of teeth from northeastern Brazilian megafauna

Two Stegomastodon waringi teeth from Brazilian northeastern megafauna were dated by electron spin resonance (ESR) spectroscopy. The samples were collected in Pernambuco state, Brazil. The dating of these samples will contribute to the better knowledge of megafauna presence in this region as well as to the events associated to the extinction of these species. Additive dose method was used to evaluate the archeological dose (AD) and a non-linear relation between ESR signal amplitude and dose was obtained. The AD obtained by the exponential fitting was 120 ± 1 and 112 ± 1 Gy , leading to an estimation of an age of 63 ± 8 and 60 ± 9 ky for radioisotope early uptake model, 64 ± 8 and 60 ± 9 ky for linear uptake and 60 ± 9 ky for a combination of uptake processes.

Thermoluminescence dating of a mikveh in Ichenhausen, Germany

A vaulted basement found at the rabbi's residential house which was oriented according to the requirements of a mikveh has created a controversy in the architectural history of the Ichenhausen Synagogue (Germany). The rabbi's residential house is known to have been built in 1781 during the replacement of the old Synagogue that had existed since 1687. However, the architectural documents concerning the residential house did not contain any information about either the presence or the construction of the mikveh in the basement. Three bricks collected from the northern, eastern and southern walls of the vaulted basement of the rabbi's residence were dated using the thermoluminescence method to find out if the mikveh belongs to the old Synagogue or was built during the construction of the residence. The archaeological dose was assessed using multi-aliquot regenerative and additive dose techniques using quartz extracted from bricks. The age calculations were based on the assessment of annual dose rate in quartz by taking into account the possible variations of water content in bricks. The TL dates of the bricks were found to vary between 1797 ± 11 and 1772 ± 16 for dry and water saturated environments, respectively. The TL results ruled out the possibility that the walls of the mikveh belong to the former Synagogue.

ESR dating of an ancient goat tooth from Nuoro, Sardinia, Italy

The dating of fossil teeth of an ancient goat (Nesogoral melonii) using the electron spin resonance (ESR) technique is reported. This animal was found in the fossiliferous site at Orosei (Nuoro, Sardinia, Italy) and was endemic in the region. Molar teeth were cleaned and enamel was completely removed from dentine. Enamel was irradiated with a 60Co gamma source and measured with an ESR spectrometer (X-band) to obtain the signal vs. dose curve and fitted with an exponential function. The archeological dose obtained by the fitting was 211 +/- 34 Gy. Uranium and thorium concentrations were determined by neutron activation analysis. With the software ROSY the age estimates were 195 +/- 30 ky for early uptake, 247 +/- 40 ky for linear uptake and 243 +/- 40 ky for a combination of uptake processes.

Electron spin resonance dating of shells from the sambaqui (shell mound) Capelinha, São Paulo, Brazil

Capelinha is a fluvial sambaqui (Brazilian Shell Mound) located in the Ribeira Valey in the State of São Paulo that is being studied. It is one of the oldest sambaquis located along a river dated so far in this region. The use of ESR to date other shells stimulated our group to apply this method to the Capelinha site. Shells from land snails (Megalobulimus sp.) obtained in two levels of excavations were analyzed; one of them was in contact with a skeleton that was dated by C-14. The archeological doses obtained were (8.05±0.07) Gy and (9.50±0.03) Gy. Since the last site was previously dated by C-14 (Beta -Analytics, Beta 153988) giving: 8860 +/- 60 years BP (conventional age) and 10180 to 9710 years BP (calibrated age), the archeological dose found for this shell was used to determine the local rate of (0.93 to 0.98) mGy/year, that aggress with other surveys done in the region. Using this dose rate the age of the second shell was found to be 8.14 to 8.73 ky BP that agrees with the stratigraphy of the site.

ESR dating at K and X band of northeastern Brazilian megafauna

The archaeological dose (AD) was measured in three tooth samples of giant mammals that belonged to Brazilian megafauna using electron spin resonance (ESR) spectroscopy at X-band (ν ∼9.5 GHz) and K-band (ν ∼24 GHz). Samples were collected in Lagoa de Dentro, Puxinanã city in Paraiba, a northeast state in Brazil and were identified as Haplomastodon waringi (Holland) (two teeth) and one tooth sample of Xenorhinotherium bahiense (Cartele and Lessa). The average AD led to an age for the Haplomastodon samples of 11.6 ky bp. For one sample ( Haplomastodon) K-band was also employed to evaluate the AD. The K-band spectrum had three components, determined using spectral simulation as follows: a wide isotropic line with g factor 2.0048, an orthorhombic line with g x = 2.0034 , g y = 2.0022 and g z = 1.9974 , and another isotropic line with g factor 2.0008. The amplitude of these three signals increase with the added dose and the average dose found was 26±5 Gy. This result is compatible with the AD determined with X-band 21±3 Gy.

Artificial optical bleaching of the Aluminium center in quartz implications to ESR dating of sediments

Electron spin resonance (ESR) dating of quartz extracted from sediments may contribute to elaborate a Neogene and Quaternary chronostratigraphy, especially in the case of azoic deposits, when methods such as thermoluminescence or K/Ar cannot be applied. The ESR method is applicable for aeolian, littoral and fluvial sediments when quartz is zeroed or bleached by an optical phenomenon (photoelectric effect due mainly to UV solar rays in this case). ESR dating on bleached quartz is based on the presence of paramagnetic substituted atoms in the crystal lattice. The Al-center can be optically bleached, and its signal intensity decreases in fossil samples versus exposure to the solar light. After a long time, the ESR intensity reaches a plateau value corresponding to the electrons which cannot be “extracted” by the light energy. These electrons represent a “residual” dose which must be subtracted from the total equivalent dose in order to obtain the archaeological dose. Our kinetic study has the objectives of obtaining a new modelization and to establish a correct time of natural bleaching for using quartz sample as appropriate for dating. We have investigated samples from a fossil fluvial sand from the Creuse river terraces system (France). Our experimental bleaching curve obtained is compared with that one previously proposed by Walther and Zilles (Quat. Sci. Rev. 13 (1994) 611).

Searching for precision of a new “luminescence clock” in dating calcitic rocks

The novel method of thermoluminescence (TL) dating of megalithic (cyclopean) limestone monuments and/or marble statues will be briefly reviewed. The problems and recent examples to be discussed include: (a) the determination of the accumulated archaeological dose, Dar, (b) the sample homogeneity, (c) the scattering in TL measurements, (d) the rate in solar bleaching of TL, and (e) dose-plateau inconsistencies. In retrospect, the solar bleaching of TL in some marbles refers to at least 30 mm depth, the scattering of TL measurements at best varies around ±10%, and the partial bleaching technique should be prudently applied for Dar determination. The extension of this method to date (by TL or OSL) for other rock types is discussed.

Luminescence dating of Somero sacristy, SW Finland using the 210°C TL peak of quartz

The 210°C thermoluminescence (TL) peak of quartz, extracted from brick fragments of Somero sacristy (Finland), which were partly elements of construction, were used for the measurement of archaeological dose for the purpose of dating. The annual gamma dose-rate with cosmic component and beta dose rate of bricks were measured using two types of TLD detectors (AL 2O 3–C) inserted in situ and in laboratory, respectively. The improvements in the precision of the TL measurements, components of annual dose assessment are described, and the results of TL age determination are discussed and compared with the archaeologically expected age.

Processes of sensitization of thermoluminescence in insulators

The increase in sensitivity of quartz caused by or irradiation followed by high-temperature activation has been studied further. The model previously suggested, including a reservoir through which holes get into the recombination centre, thus increasing the sensitivity to a given test dose, is now given a concrete mathematical form. Sets of simultaneous differential equations for the various stages of irradiation and heating are written and numerically solved sequentially in order to simulate the physical processes taking place during the experiments. The dependence of the sensitivity on the excitation dose is followed, in particular for the high-dose range in which the sensitivity approaches saturation. A distinction between reservoir and centre saturation is made. The assumption of an exponential approach to saturation is tested, showing that, indeed, even in this complicated situation the exponential approximation is valid. As shown in previous works, using the exponential approximation in cases in which the sensitivity dependence is beyond the linear range helps in evaluating the archaeological doses in the dating of pottery by irradiation of the quartz grains in it. Also the effect of radiation quenching and the attempts to correct for quenching in order to improve the determination of the extrapolated natural dose which leads to the age determination are considered. The effect of the existence of a competing electron trap which appears to be a necessary condition for the occurrence of these effects is also discussed.

The Archeologial Dating Method by Electron Paramagnetic Resonance

Os princípios físicos do método de datação arqueológica utilizando a espectroscopia de ressonância paramagnética eletrônica (RPE) são apresentados. Esta técnica espectroscópica permite uma quantificação da concentração de radicais livres estáveis presentes na amostra criados pela radiação ambiental. Através dessa medida é possível determinar-se a dose de radiação, conhecida como dose arqueológica, necessá­ ria para a produção da concentração desses radicais. Conhecendo-se a taxa de dose ambiental no sítio onde a amostra está depositada é possível converter essa dose em idade da amostra. Esse método é não destrutivo, aplica-se a amostras de ossos, carbonatos, silicatos, e outros materiais isolantes elétricos e quantidades da ordem de 0.1 gramas são necessárias

The temple of apollo (Delphi) strengthens novel thermoluminescence dating method

The temple of Apollo in Delphi (Greece), built in 550 B.C., has been used to reconfirm a novel method of dating carved megalithic stone buildings using thermoluminescence (TL) (Liritzis, 1994). A calcitic (marble) sample was taken from the western side of the well-known inscribed polygonal wall, which constitutes the southern external support foundations of the temple. A partially bleached TL methodology was devised to determine first the ancient residual TL and then the correct archaeological dose. The obtained TL age of 420 ± 300 B.C. is compatible, within the margin of error, with the archaeological age. © 1997 John Wiley & Sons, Inc.

Datation par thermoluminescence d'un niveau néolithique ancien à la Lède du Gurp (Gironde), comparaison avec les dates radiocarbone

ABSTRACT A piece of pottery extracted from an early Neolithic level belonging to the Atlantic Cardial Culture at La Lède du Gurp (Gironde, France) has been dated by thermoluminescence. The archaeological dose (i.e. palaeo- dose) was determined using the fine grain technique; the annual dose was assessed from the data obtained by low background gamma spectrome- try and by on site environmental do- simetry. The TL (ThermoLumines- cence) result : BDX 2024 : 6450 ± 520 years before 1991, i.e. around 4460 ВС, agrees with the radiocarbon dates of wood pieces which were found in the close surroundings of the sherds of pottery : 4680-4380 ВС (Ly-5320) after calibration — 95% probability level — and 4800-4530 ВС (Ly-5319).

TL and radiocarbon dating of neolithic sepultures from Sudan: Intercomparison of results

Thermoluminescence dating of a set of 29 pottery sherds excavated at the neolithic sites of El Kadada and El Ghaba (near Shendi, Central Sudan) was carried out at Bordeaux University. The archaeological dose was measured using the fine grain technique. The annual dose was determined by analytical techniques (neutron activation analysis, ICP spectrometry, XRF, low background gamma spectrometry) and by “on-site” measurements of the environmental radioactivity (gammametry). The crystalline inclusions of the samples were characterized by optical microscopy and cathodoluminescence: the TL minerals mainly consist of quartz and K-feldspar crystals. In some cases, radioactive inclusions of zircons and monazites are observed. The TL and the radiocarbon dates show a good agreement, verifying the validity of the radiocarbon ages which were suspected to be too old because of the nature of the dated material (shells). Taking into account all the chronological data, it is shown that El Ghaba and El Ghaba necropolis were used respectively within the 4800-3300 B.C. and 4200-3000 B.C. date-ranges for neolithic cultures, the occupation of El Kadada starting five or six centuries later than El Ghaba.

Fading of thermoluminescence in feldspars: Characteristics and corrections

Abstract The combination of high TL sensitivity, linearity of growth characteristics, and significant internal beta activity make alkali feldspars attractive for TL dating. The common observation of short term fading however offsets some of these advantages and has, no doubt, inhibited the spread of feldspar dating methods. The empirical aspects of short term fading in feldspar samples from vitrified forts and ceramics are considered here. In particular the dependence of fading on glow curve temperature, radiation dose and storage regime are discussed, together with the effect of fading corrections on the quality of dating plateaux. As with other TL properties a diverse range of behaviour is observed from different samples. A consideration of the light sums involved in TL glow curves from feldspar samples, and the ionisation produced at typical archaeological doses shows that fading cannot be ascribed to simple proximity models based on randomly distributed traps and recombination centres. The origins and long term behaviour of fading thus remain obscure. Nevertheless a case can be made for correcting for the fading observed in periods ranging from several days to several months and there are signs that some unstable signals can be removed rapidly by preheating samples. Such thermal blocking routines are discussed.

An analytical model for the growth of ESR signals

We have developed an analytical model for the time- and dose-dependency of ESR signals in calcite. The model describes well the observed natural growth and the growth by artificial irradiation of ESR-signals (g = 2.0034 and g = 2.0006) in deep-sea foraminifera. The model shows how to derive the archaeological dose from the artificial growth curve of ESR signals. Applying the model we have determined the lifetime of the signal at g = 2.0006 to be about 350 ka at 2°C. The thermal decay of the traps responsible for that signal was shown by heating experiments.

Progress of ESR studies on CaCO 3 of deep sea sediments

The archaeological dose (AD) derived from the g = 2.0006 line of the ESR spectra of foraminifera from deep sea cores V12-122 and 13519 lies close to the expected value derived from the specific radioactivity and the known ages of the sediment layers. To the contrary, the archaeological dose (AD) for the g = 2.0034 line is approx. a factor of 2 larger than the total dose expected. On the basis of the present data, the thermal life time of the electron traps corresponding to the ESR-line at g = 2.0006 line is estimated to > 750,000 yr. The k α factor of foraminifera should be ≤0.1.