Towards an improvement of optically stimulated luminescence (OSL) age uncertainties:Modelling OSL ages with systematic errors, stratigraphic constraints and radiocarbon ages using the R package BayLum

International audienceAbstract. Statistical analysis has become increasingly important in optically stimulated luminescence (OSL) dating since it has become possible to measure signals at the single-grain scale. The accuracy of large chronological datasets can benefit from the inclusion, in chronological modelling, of stratigraphic constraints and shared systematic errors. Recently, a number of Bayesian models have been developed for OSL age calculation; the R package “BayLum” presented herein allows different models of this type to be implemented, particularly for samples in stratigraphic order which share systematic errors. We first show how to introduce stratigraphic constraints in BayLum; then, we focus on the construction, based on measurement uncertainties, of dose covariance matrices to account for systematic errors specific to OSL dating. The nature (systematic versus random) of errors affecting OSL ages is discussed, based – as an example – on the dose rate determination procedure at the IRAMAT-CRP2A laboratory (Bordeaux). The effects of the stratigraphic constraints and dose covariance matrices are illustrated on example datasets. In particular, the benefit of combining the modelling of systematic errors with independent ages, unaffected by these errors, is demonstrated. Finally, we discuss other common ways of estimating dose rates and how they may be taken into account in the covariance matrix by other potential users and laboratories. Test datasets are provided as a Supplement to the reader, together with an R markdown tutorial allowing the reproduction of all calculations and figures presented in this study

Importance of field data for understanding a potential Mousterian funerary deposit : the case of the Regourdou 1 skeleton (Montignac-sur-Vézère, Dordogne, France)

Aside from the work of Bonifay (see Bonifay et al. 2007 for one of the more recent papers) and various articles following these earlier works (e.g., Binant 1991, Defleur 1993, Maureille et Vandermeersch 2007, Pettitt 2011, see also May 1986 for a more critical analysis), the in situ position of the remains of Regourdou 1 from layer 4 has never actually been discussed on the basis of available data from the salvage operation carried out in October 1957 by E. Bonifay and G. Laplace-Jauretche, under the administrative authority of François Bordes, or from the subsequent, more systematic, excavations directed by E. Bonifay between 1961 and 1964. Via the compilation of available information from a number of unpublished documents (François Bordes’ field notes, drawings made during the salvage operation, photographs taken in 1957, 1961 and 1962, as well as databases from the 1961 to 1964 excavations), and also a new inventory of human remains (both previously known and recently discovered), it is now possible to more accurately reconstruct the position of the human remains in a Cartesian system. In this, we assume that the concentration of remains uncovered during the salvage operation was in square G2, according to the preliminary systematic excavations carried out in 1961. They also bring to light that while practically no anatomical connections can be demonstrated with any certainty – and despite significant disruptions (all of the hominin remains are spread over 9 squares : G1 to G3, F1 to F3, E1 and E2, D2) – they are mainly positioned in squares G2 and G3 to some degree with respect to the anatomical logic of the human body. We therefore assume that Regourdou 1 was lying flat, with its head to the west – perhaps upon its trunk – close to the wall of the cavity. This result is different from the fetal position hypothesis proposed in Bonifay et al. (2007). Moreover many post-depositional (albeit Pleistocene) disturbances are also evident. We believe that they were likely the result of the utilization and modification of the cavity by brown bears and lagomorphs.Only new excavations at the site, and a better taphonomic understanding of Bonifay’s (1964) layer 4 (in which Regourdou 1 was found), and the exact role of humans in its formation, i.e., their anthropic impact on the layer, will allow us to discuss in more detail the nature of the deposition of the body, and, hopefully, the absence of the skull

Las contribuciones de la datación por luminiscencia en la arqueología sudamericana : ciertas aplicaciones al patrimonio andino, algunas aplicaciones en las primeras ocupaciones humanas de América

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Nouveaux apports de la thermoluminescence à la chronologie du Paléolithique dans le Sud-Ouest de la France: Etudes en milieu hétérogène et en présence de déséquilibres radioactifs dans les séries de l'uranium

Understanding and knowing the Paleolithic requires a better mastery of its chronology. We have carried out a critical census of the dates corresponding to the Middle Paleolithic of south-west France. It highlighted a significant deficit in digital dating, particularly for outdoor sites and the oldest periods. We then carried out thermoluminescence (TL) dating on three Middle Paleolithic sites in the southwest, Petit Bost and Croix de Canard (Neuvic/Isle), and Roc de Marsal (Campagne), and on a Magdalenian site, La Honteyre. (The Tuzan). These studies required specific methodological research, in order to obtain the most accurate and reliable dates possible. The thermal cycle most suited to annealing was studied, as well as the problems posed by the radioactive heterogeneity sometimes presented by the surrounding environment. We also carried out an experiment aimed at simulating the transport of photons based on Monte Carlo type methods. Finally we proposed solutions, based on and spectrometry, to take into account the existence of radioactive imbalances in the uranium chains. The Early Paleolithic level of Petit Bost could thus be dated at 319 ± 19 kilo-years, and the occupation associated with the MTA of Croix de Canard at 79.3 ± 4.4 kilo-years. The dating of layer B of Roc de Marsal provides a terminus ante quem to the Mousterian levels defined in the cave and to the "burial" of the child. Finally, the occupation of the La Honteyre hunting camp, as well as the engraved pebble associated with it, could be dated to 12,200 ± 800 BC. B.C.La compréhension et la connaissance du Paléolithique nécessitent une meilleure maîtrise de sa chronologie. Nous avons effectué un recensement critique des datations correspondant au Paléolithique moyen du sud-ouest de la France. Il a mis en évidence un déficit important en datations numériques, en particulier pour les sites de plein air et les périodes les plus anciennes. Nous avons alors effectué des datations par thermoluminescence (TL) sur trois sites du Paléolithique moyen du sud-ouest, Petit Bost et Croix de Canard (Neuvic/Isle), et Roc de Marsal (Campagne), et sur un site magdalénien, La Honteyre (Le Tuzan). Ces études ont nécessité des recherches méthodologiques particulières, afin d'obtenir les dates les plus justes et fiables possibles. Le cycle thermique le plus adapté au recuit a été étudié, ainsi que les problèmes posés par l'hétérogénéité radioactive parfois présentée par le milieu environnant. Nous avons également effectué une expérience visant à simuler le transport des photons basée sur des méthodes de type Monte Carlo. Enfin nous avons proposé des solutions, à partir des spectrométries et , pour prendre en compte l'existence de déséquilibres radioactifs dans les chaînes de l'uranium. Le niveau du Paléolithique ancien de Petit Bost a ainsi pu être daté à 319 ± 19 kans, et l'occupation associée au MTA de Croix de Canard à 79,3 ± 4,4 kans. La datation de la couche B de Roc de Marsal fournit un terminus ante quem aux niveaux moustériens définis dans la grotte et à " l'inhumation " de l'enfant. Enfin l'occupation du camp de chasse de La Honteyre, ainsi que le galet gravé qui lui est associé, ont pu être datés à 12 200 ± 800 av. J.C

Nouveaux apports de la thermoluminescence à la chronologie du Paléolithique dans le Sud-Ouest de la France

La compréhension et la connaissance du Paléolithique nécessitent une meilleure maîtrise de sa chronologie. Nous avons effectué un recensement critique des datations correspondant au Paléolithique moyen du sud-ouest de la France. Il a mis en évidence un déficit important en datations numériques, en particulier pour les sites de plein air et les périodes les plus anciennes. Nous avons alors effectué des datations par thermoluminescence (TL) sur trois sites du Paléolithique moyen du sud-ouest, Petit Bost et Croix de Canard (Neuvic/Isle), et Roc de Marsal (Campagne), et sur un site magdalénien, La Honteyre (Le Tuzan). Ces études ont nécessité des recherches méthodologiques particulières, afin d'obtenir les dates les plus justes et fiables possibles. Le cycle thermique le plus adapté au recuit a été étudié, ainsi que les problèmes posés par l'hétérogénéité radioactive parfois présentée par le milieu environnant. Nous avons également effectué une expérience visant à simuler le transport des photons basée sur des méthodes de type Monte Carlo. Enfin nous avons proposé des solutions, à partir des spectrométries et , pour prendre en compte l'existence de déséquilibres radioactifs dans les chaînes de l'uranium. Le niveau du Paléolithique ancien de Petit Bost a ainsi pu être daté à 319 +- 19 kans, et l'occupation associée au MTA de Croix de Canard à 79,3 +- 4,4 kans. La datation de la couche B de Roc de Marsal fournit un terminus ante quem aux niveaux moustériens définis dans la grotte et à "l'inhumation" de l'enfant. Enfin l'occupation du camp de chasse de La Honteyre, ainsi que le galet gravé qui lui est associé, ont pu être datés à 12200 +- 800 av. J.C.BORDEAUX1-BU Sciences-Talence (335222101) / SudocBORDEAUX3-BU Lettres-Pessac (335222103) / SudocSudocFranceF

Le cadre chronologique : méthodes et résultats

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Luminiscence dating at Cueva de Covalejos (Cantabria, Spain): preliminary results

International audienceLuminescence dating is an appropriate method to determine the age of sediments (Aitken, 1985; 1998). Ubiquitous minerals such as quartz and feldspar store radiation energy delivered by natural radionuclides (mainly potassium and the uranium and thorium decay series). This energy can then be released by optical stimulation in the form of luminescence signal: this phenomenon is called Optically Stimulated Luminescence (OSL). By dividing the dose received by the mineral (through OSL measurements) by the dose rate it has been exposed to (through gamma spectrometry and/or in situ gamma dosimetry), one can estimate the time elapsed since the last exposure to light and subsequent burial (age)

The Cerutti Mastodon Site: Archaeological or Paleontological?

International audienceThe newly reported California discovery of mastodon remains possibly altered by humans more than 130 ka is unprecedented and potentially transformational. It calls for a concerted effort in North and South America to investigate other such ancient contexts that substantially predate the commonly accepted late-glacial timing of the first peopling of the New Worl