Thermoluminescence Dating Research Articles

Duplicitous thermoluminescence peak associated with a thermal release of electrons and holes from trapping states

A thermoluminescence (TL) glow peak may result from a transition of electrons from traps into the conduction band, followed by a recombination with holes trapped in a luminescence center. Another possibility is that holes trapped in a hole trap are thermally released into the valence band and recombine with electrons in an electron recombination center. A series of glow peaks emitted from a given sample may include peaks of both kinds. In some cases, peaks may be identified as being of one kind or the other, say, by using thermally stimulated electron emission (TSEE), which can take place when the free carriers are electrons. In the present work, we demonstrate by the use of simulation that two peaks may result from one electron and one hole trapping states and a single hole recombination center. The first TL peak is observed when thermally stimulated electrons recombine with holes in the center. The TL peak is terminated when the holes in the center are exhausted. At higher temperatures, holes from a hole trap are released into the valence band and then captured by the hole center, thus this center is replenished. More electrons from the electron trap are thermally released now and recombine with the newly arrived holes in centers. A second TL peak may be observed which carries some information concerning the hole trap. It is thus demonstrated that some of the usual methods for distinguishing between electron and hole traps can lead to incorrect conclusions. It is possible for a hole trap, for example, to induce an increase in electron recombination in such a way that it produces a peak that looks nearly identical to TL from an electron trap. This simulation may bring about a new look at TL peaks occurring in materials used in TL dosimetry and dating. A new interpretation may also be given to “Auger” TSEE associated with the thermal release of electrons from the surface of a material, which indirectly results from the thermal release of holes from traps. The performance of some methods for evaluating the activation energies and the significance of the results in the present situation are discussed.

Advantages and limitations of thermoluminescence dating of heated flint from Paleolithic sites

AbstractThermoluminescence (TL) dating is now widely used in the age determination of Paleolithic sites. Although the basic principle of TL‐dating is simple, the underlying assumptions are not trivial. One major source of error is the external dose rate, which contributes to a varying degree to the denominator of the age formula and thus has a varying influence on the dating result. The intention of this paper is to enable the user to evaluate TL age determinations of heated flint. The parameters used for age determination and some of their relationships are discussed. It is shown that the reliability of TL results of heated flint depends on the proportion of the various dose‐rate parameters and that these are important for the evaluation of ages. The limitations of the method as well as the advantages are discussed. TL‐dating results for two Near Eastern Paleolithic sites (Rosh Ein Mor and Jerf al‐Ajla) are discussed as examples. © 2007 Wiley Periodicals, Inc.

Formation of the Yellow River, inferred from loess–palaeosol sequence in Mangshan and lacustrine sediments in Sanmen Gorge, China

The formation of the Yellow River was a significant geological and hydrological event in the history of landscape evolution in northern China, resulting from interactions between various Earth System processes. Earlier concepts about the ages of the river's formation are quite controversial. This paper investigates the age of the Samen Gorge, the last gorge along the course of Yellow River before it reaches the sea. The main research materials presented here are: (a) 172.1-m-thick loess–palaeosol sequence in Mangshan located in the south side of the Yellow River, (b) Lacustrine sediments of the former Sanmen Lake. The chronology is based on the stratigraphical correlations with the well-dated loess–palaeosol sequence in Luochuan of central Loess Plateau, palaeomagnetism and optically stimulated luminescence (OSL) and thermoluminescence (TL) datings. An abrupt increase in the rate of sedimentation is recognized in the stratigraphical layers L 2 and above of the Mangshan sequence. The loess unit L 1 and palaeosol unit S 1 of Mangshan are much thicker than those of other sections in Loess Plateau as well, indicating a new and unique source only for the Mangshan region. The aeolian deposition of the loess is found to have started at ca. 150 ka in the bottom of the former large lake west of the Sanmen Gorge and suggests desiccation of the former Sanmen lake. At this point in time, the Yellow River could bring large amount of fluvial sediment east of the Sanmen Gorge after the gorge was downcut. The fluvial sediment is suggested to be the new source of loess identified in the Mangshan sequence. Therefore, it is concluded that the downcutting of the Sanmen Gorge started at ca. 150 ka and indicates the full development of the Yellow River.

Aberrant thermoluminescence dates obtained from primary volcanic quartz

This study deals with the dating by thermoluminescence (TL) of quartz from six volcanic formations of the Saint Lucia Island (Lesser Antilles Arc). Quartz microcrystals up to one millimetre in size were extracted from dacites and pumice flows and prepared in a way similar to the well-known inclusion technique. The TL properties of these quartz were used to estimate apparent palaeodoses using the multi-aliquot protocol. The quartz TL was studied in three different spectral domains: red, green and ultraviolet/blue. The calculated annual dose-rates yielded a set of 18 age-estimates. For some samples complementary dates were obtained using high temperature TL (HTTL) of plagioclase feldspars. These latter dates combined with previously determined radiocarbon and unspiked K–Ar dates were used to explore the validity of ages computed from the TL of quartz. Individual values for quartz appear to be scattered and do not match ages deduced from 14C, unspiked K–Ar or HTTL on plagioclase dates. These results indicate that when conventional TL methodologies derived from the inclusion method are applied to volcanic quartz major dating problems are to be expected.

A contribution to the study of post-depositional alterations of pottery using TL dating analysis

In luminescence dating, the potassium concentration significantly contributes to the dose rate value in the age estimation. Within this study, fine-grain thermoluminescence dating has been applied on sherds of calcareous pottery of known age, excavated at a Roman site in Mallorca, Spain. For those of the samples that showed signs of severe potassium leaching, according to chemical and mineralogical examination, the thermoluminescence analysis provided overestimated dates. By using the known archaeological age of the samples, a corrected dose rate value can be estimated which provides the potassium concentration averaged for the burial period. Finally, a step-like model can then be used to estimate the fraction of the burial period after which most of the alteration effects took place.

Paleoecology reconstruction from trapped gases in a fulgurite from the late Pleistocene of the Libyan Desert

When lightning strikes the ground, it heats, melts, and fuses the sand in soils to form glass tubes known as fulgurites. We report here the composition of CO 2 , CO, and NO contained within the glassy bubbles of a fulgurite from the Libyan Desert. The results show that the fulgurite formed when the ground contained 0.1 wt% organic carbon with a C/N ratio of 10–15 and a δ 13 C of –13.96‰, compositions similar to those found in the present-day semiarid region of the Sahel, where the vegetation is dominated by C 4 plants. Thermoluminescence dating indicates that this fulgurite formed ~15 k.y. ago. These results imply that the semiarid Sahel (at 17°N) reached at least to 24°N at this time, and demonstrate that fulgurite gases and luminescence geochronology can be used in quantitative paleoecology.

A Ceramic Plaque Representing a Part of the Moses Panel by Lorenzo Ghiberti in the East Baptistery Doors (Florence, Italy)

AbstractA ceramic plaque was studied that depicts the figurative part of the lower half of the Moses Panel from the gilt bronze doors that Lorenzo Ghiberti and his workshop installed on the east side of the San Giovanni Baptistery in Florence, Italy. The doors were completed in 1452, and thermoluminescence dating of two areas of the ceramic relief panel gave a broad, but consistent fifteenth century date. No differences were found in the composition, microstructure or phase assemblage of the two stylistically distinct parts of the ceramic panel. Microscopy and radiography were used to reconstruct the forming methods and sequence of steps in manufacture and restoration.

Chronology of Fortified Settlements in East Timor

ABSTRACT This paper presents new data on the possible ages and functions of stone structures in the eastern regions of East Timor. Radiocarbon and thermoluminescence dates were obtained from samples from a number of these sites which suggest a late Holocene period construction and occupation. Results from small scale excavations at three sites suggest that these structures were fortified village sites. These social forces behind the building and use of these sites may be related to wider regional social and environmental factors over the last few thousand years.

Establishing the time of initial human occupation of Liang Bua, western Flores, Indonesia

Liang Bua, a limestone cave in western Flores, has an archaeological and faunal sequence known to span the last 95 ka and is the type-site for a small-bodied hominid species, Homo floresiensis. This paper describes the geomorphic history of this significant site, and presents numerical ages for key events as determined by thermoluminescence dating of sediments (using a dual-aliquot regenerative-dose protocol) and uranium-series dating of flowstones. Our age estimates indicate that Liang Bua existed as a subterranean chamber by 400 ka ago. It was subsequently exposed by the incision of the Wae Racang River, which invaded the cave around 190 ka and deposited an upward-fining sequence of water-rolled boulders and cobbles. The latter conglomerate was partially reworked around 130 ka ago and was capped by flowstones at 100 ka. The conglomerate also contains stone artefacts, which implies that the occupation of the surrounding area is at least as old as the time of emplacement of the conglomerate. After 190 ka, a complex sequence of erosion and deposition led to the accumulation of at least 11 m of sediment in the front chamber of the cave, which proved suitable for hominid occupation. Such geochronological and geomorphological information is extremely valuable for interpreting the archaeological record at Liang Bua and its wider significance.

Thermoluminescence dating of heated flint from the Mousterian site of Bérigoule, Murs, Vaucluse, France

The stratigraphic and lithic evidence at the site of Bérigoule is not sufficient for the determination of the age of two Mousterian archaeological layers. Thermoluminescence (TL) dating of heated flint from the two levels provides chronometric age estimates. The TL-ages show a high degree of variability, ranging from 54 to 90 ka for Level I and 67 to 111 ka for Level II. The technological and sedimentological analyses suggest a similar age for the artefacts from the two layers, which is supported by the TL-data. All these data suggest that the artefacts of Levels I and II were heated at the end of OIS 5.

Review of the timing and extent of glaciers during the last glacial cycle in the bordering mountains of Tibet and in East Asia

New accelerator mass spectrometry 14C (AMS 14C), electron spin resonance (ESR) and thermoluminescence (TL) dates for glacial successions in Tibetan bordering mountains and in East Asia show that glacier extent during the early/middle (MIS3-4) parts of the last glacial cycle was larger than that of the late stage (MIS2) in last glacial cycle. Glaciation was not synchronous with the North Hemisphere ice sheet maxima and changes in oceanic circulation that predominately control global climate. There exist three seasonal precipitation patterns that control the accumulation and ablation on glaciers in the study areas. Areas dominated by Westerlies, including the East Asia coastal islands, experience glacier advance mainly because of increased winter precipitation. These glaciers expand during glacial stages. In contrast, in areas dominated by summer precipitation in the interior of mainland, except in the monsoonal high precipitation zone in southeast Tibet and the Hengduan Mountain range, tend not to develop large glaciers during major glacial stages.

Surface resetting of thermoluminescence in milled quartz grains

Thermoluminescence (TL) dating of fault movements assumes TL resetting in gouges during faulting due to frictional heating. However, this assumption is often doubted. Here, we quantitatively examine the TL resetting in milled grains of quartz previously 1 kGy dosed. The TL intensity as a function of the grain diameter indicated the TL reduction only in surface layers of unetched grains. The layer thickness was estimated to be about 500 nm based on the comparison with a model. This TL reduction layer is equivalent to the surface disordered layer that has been found to be generally amorphous and/or highly disturbed due to thermal and mechanical damage during milling and faulting. For detailed modeling of TL resetting during milling and faulting, both frictional heating and mechanical deformation of the surface structure need to be considered. Fine or finest gouges are potentially the best type of sample for TL dating of fault movements.

Morphology and stratigraphy of the late Quaternary lower Brazos valley: Implications for paleo-climate, discharge and sediment delivery

A shallow coring and geophysical logging program has recorded the sedimentary fill of the Brazos River valley in the Texas Gulf Coastal Plain. Thermoluminescence dates together with new and recalibrated published radiocarbon dates show the valley fill to include extensive, sandy, buried falling stage and lowstand Oxygen Isotope Stage (OIS) 3 and 2 deposits. These alluvial deposits are punctuated by numerous paleosoil horizons that record alternating periods of cutting, bypass and accumulation. Maximum valley incision and two periods of terrace formation preceded marine lowstand conditions, suggesting significant discordance between preserved fluvial and classical marine system tracts. The latest Pleistocene incision and fill history appears related to cycles of increased discharge and incision, followed by system equilibration and terrace formation. Analysis of the Brazos River incised valley and its contained paleochannels indicates that latest Pleistocene mean annual discharge was as much as four times greater than that of today. This magnitude of discharge in the Brazos would require a two-fold increase in precipitation across the drainage basin. Such an increase is comparable to the present day measured positive El Niño winter precipitation anomaly across the region. Paleochannel geometries and the stratigraphic and sedimentologic data from this investigation support the hypothesis that periods of high-amplitude, El Niño-like climatic perturbations characterized the late Quaternary climate of the south-central and southwestern U.S. This period of high discharge coincides, at least in part, with late OIS 3 progradation of the Brazos delta to the shelf margin, OIS 3 and 2 valley incision across the Texas shelf, and concomitant sand bypass to intraslope basins beyond the shelf edge.

Equivalent dose (palaeodose) estimation in thermoluminescence dating using a single aliquot of polymineral fine grains

A single aliquot protocol for the estimation of the natural dose in thermoluminescence dating (SATL) is presented that makes use of polymineral fine grains extracted from ceramic materials. The protocol is demonstrated using aliquots made from two Neolithic sherds and is compared with results from an additive dose polymineral technique. The results of both techniques are in close agreement and highlight the potential advantages of the new procedure, especially when sample availability is restricted, e.g. dating of small pottery fragments, or in cases of authenticity testing.

Dating the Quaternary: progress in luminescence dating of sediments

Luminescence dating comprises a collection of numerical-age techniques that are among the most significant chronological tools currently used in Quaternary research. This paper briefly reviews the key historical developments in luminescence dating, from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight-exposed sediments. We describe the principles and practicalities of the various techniques commonly used in luminescence dating, including multiple-aliquot, single-aliquot and single-grain procedures, and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation (e.g., by means of component analysis and dose distribution methods in optical dating). The overview also introduces the other papers in this special issue of Quaternary Science Reviews, which address a selection of important issues in basic research, technique development and application of luminescence dating to critical questions in the geological and archaeological sciences, illustrated with examples from around the world and the last million years of Earth history.

TL dating of feldspars using their far-red emission to deal with anomalous fading

New studies of thermoluminescence (TL) dating of feldspars involving their far-red emission are proposed. The intense TL of feldspars is affected by the pervasive effect of anomalous fading, a strong deterrent to their use for TL dating. With volcanic feldspars, the natural TL can fade completely. With other feldspars, such as found in sediments, anomalous fading may turn out to be weaker and correct TL dates could be obtained. This effect of fading may be dealt with methods based on the little studied far-red emission, a band centred around 710 nm present in the TL of all feldspars. Apparently this emission does not fade during geological storage, or at least much less than the visible and UV (‘blue’) emissions used by conventional TL, OSL or IRSL readers. This emission has enabled dating by TL and has been expanded to IRSL. These TL experiments are resumed with improved methods for filtering, collection of data and protocols. Firstly, the stability of TL in some sediments is tested by the B ir protocol. B ir is the ratio of the conventional ‘blue’ emission to the far-red emission measured simultaneously in the course of a TL measurement by use of filters on a carousel. Comparison of the values of B ir between prompt TL and the natural TL provides a sensitive gauge of the stability of conventional TL, which is verified notably with some sediments dated by Preusser [IRSL dating of K-rich feldspars using the SAR protocol: comparison with independent age control. Ancient TL 21, 17–23.]. Secondly, two volcanic plagioclases of known age from Olby and Royat are considered. In their natural TL, the conventional ‘blue’ emission has drastically faded away but not the far-red one. Additive TL using this far-red emission leads to a satisfactory evaluation of the natural dose of these samples, hereby confirming the stability of this far-red emission during geological storage.

Thermoluminescence dating of the ancient Chinese porcelain using a regression method of saturation exponential in pre-dose technique

This paper studies the thermoluminescence (TL) dating of the ancient porcelain using a regression method of saturation exponential in the pre-dose technique. The experimental results show that the measured errors are 15% (±1s) for the paleodose and 17% (±1s) for the annual dose respectively, and the TL age error is 23% (±1s) in this method. The larger Chinese porcelains from the museum and the nation-wide collectors have been dated by this method. The results show that the certainty about the authenticity testing is larger than 95%, and the measurable porcelains make up about 95% of the porcelain dated. It is very successful in discrimination for the imitations of ancient Chinese porcelains. This paper describes the measured principle and method for the paleodose of porcelains. The TL ages are dated by this method for the 39 shards and porcelains from past dynasties of China and the detailed data in the measurement are reported.

鬼首・鳴子カルデラ周辺の後期更新世火砕流堆積物及び火山岩の熱ルミネッセンス年代

Thermoluminescence (TL) dating of volcanic rocks and pumice flows around Onikobe-Naruko area was carried out by checking suitability of the sample for this technique. Samples for TL dating were divided into three ranks, A, B and C, on the basis of physical/petrographical characters and geological origin. Rank A sample is hard and compact rock which is chemically stable. Rank B is soft pumice flow or equivalent sample which is chemically unstable for long geologic time. Rank C is sediment deposited in water. For precise and reliable TL dating, only rank A sample must be used. TL ages obtained from samples of rank A are 30.4 ka for Naruko dome lava, 187 ka for Takahinatayama lava, 169 ka and 170 ka for Shimoyamazato Tuff Formation, and 296 ka and 268 ka for Ikezuki Tuff Formation. Mitsuzawa Formation at western part of Naruko, pyroclastic flows at Yubama and Byobuiwa are identified as Ikezuki Tuff Formation due to their TL ages of 258 ka, 231 ka to 345 ka and 238 ka, respectively. TL ages of two sites are not well coincide to Ikezuki Tuff Formation. TL ages of the samples from Yubama Onsen and Gyojadaki are 169 ka and 362 ka, which correspond to the age of other eruption products rather than Ikezuki Tuff Formation. TL age data for 83 samples of rank B and C are checked by comparison with those of rank A and existence age data. It could be reconciled with stratigraphic evidence and corresponding ages of rank A. Rank B and C data are selectively apply for preliminary stage or special purposes that the rough ages are still useful for research program.

Fine-grain TL dating of archaeometallurgical furnace walls

Thermoluminescence (TL) signals of ceramic fragments from an archaeometallurgical furnace, sampled in Kythnos (Greece), were investigated using an additive dose fine-grain polymineral protocol. Based on the measurements, dates were produced that shed light on the beginnings of Cycladic Bronze Age metallurgy. Additionally, the mineralogy of the fragments was examined to study the relation between their TL characteristics and the temperatures they were exposed to during the pyrometallurgical process. The results presented here highlight sources of additional error in TL dating of ancient furnace remains, like varying sensitivity characteristics and potential mineralogical alterations.

Illuminating Southeast Asian Prehistory: New Archaeological and Paleoanthropological Frontiers for Luminescence Dating

Since the explorations of Alfred Russel Wallace and Eug�ne Dubois in the nineteenth century, Southeast Asia has been one of the world's focal points for studies of biogeography and biodiversity, human evolution and dispersal, environmental change, and the spread of culture, farming, and language. Yet despite its prominence, reliable chronologies are not available for many of the critical archaeological, evolutionary, and environmental turning points that have taken place in the region during the last 1.5 million years. In this paper, we discuss some of these chronological problems and describe how luminescence dating may help overcome them. "Luminescence dating" is a term that embraces the techniques of thermoluminescence (TL) and optical dating, which can be used to estimate the time elapsed since ubiquitous mineral grains, such as quartz and potassium feldspar, were last heated to a high temperature or were last exposed to sunlight. Luminescence methods have been successfully deployed at late Quaternary archaeological, paleoanthropological, and geological sites around the world, but not to any great extent in Southeast Asia. Here we describe the principles of TL and optical dating and some of the difficulties that are likely to arise in dating the volcanic minerals found throughout the region. We also outline several long-standing archaeological and paleoanthropological questions that are the subject of a current program of luminescence dating in Southeast Asia, and present recent dating results from Liang Bua in Indonesia and Bukit Bunuh in Malaysia.