57 research outputs found

    Infrared Radiofluorescence (IR-RF) of K-Feldspar:An Interlaboratory Comparison

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    Infrared Radiofluorescence (IR-RF) is a relatively new method for dosimetric dating of the depositional timing of sediments. This contribution presents an interlaboratory comparison of IR-RF measurements of sedimentary feldspar from eight laboratories. A comparison of the variability of instrumental background, bleaching, saturation, and initial rise behaviour of the IR-RF signal was carried out. Two endmember samples, a naturally bleached modern dune sand sample with a zero dose and a naturally saturated sample from a Triassic sandstone (~250 Ma), were used for this interlaboratory comparison. The major findings of this study are that (1) the observed IR-RF signal keeps decreasing beyond 4000 Gy, (2) the saturated sample gives an apparent palaeodose of 1265 ± 329 Gy and (3) in most cases, the natural IR-RF signal of the modern analogue sample (resulting from natural bleaching) is higher than the signal from laboratory-induced bleaching of 6 h, using a solar simulator (SLS). In other words, the laboratory sample bleaching was unable to achieve the level of natural bleaching. The results of the investigations are discussed in detail, along with possible explanations

    Infrared radiofluorescence (IR-RF) dating:A review

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    International audienceLuminescence dating methods on natural minerals such as quartz and feldspars are indispensable for establishing chronologies in Quaternary Science. Commonly applied sediment dating methods are optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). In 1999, Trautmann et al. (1999a, b) proposed a new related technique called infrared radiofluorescence (IR-RF). IR-RF denotes the infrared luminescence signal of feldspar resulting from exposure to ionizing radiation and potentially offers a significant methodological advance compared to OSL and IRSL regarding luminescence signal stability, dating range and required measurement time. The method has rarely been applied due to a lack of commercially available measurement equipment but experienced a revival during the last years. The present article provides a state-of-the-art overview of the physical background of IR-RF, its challenges, applications and the potential as a dating method. The paper particularly addresses practical considerations for applying IR-RF dating, including signal bleachability and saturation behaviour, and summarizes proposed solutions

    Feldspars as support for the luminescence dating of archaeological deposits and quaternary sequences of Aquitaine

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    Les donnĂ©es chronologiques disponibles pour les gisements du PalĂ©olithique moyen du Sud-Ouest de la France font Ă©tat d’un manque de jalons chronologiques fiables. Pour ces pĂ©riodes anciennes, l’établissement d’un cadre chronologique nĂ©cessite un investissement mĂ©thodologique important dans le domaine de la datation numĂ©rique. Les rĂ©sultats obtenus dans cette Ă©tude reposent essentiellement sur la datation par luminescence optique de grains de feldspaths et de quartz contenus dans les sĂ©diments. En particulier, l’étude des signaux de luminescence classiquement exploitĂ©s (IRSL, pIR-IRSL), nous permet de mieux Ă©valuer la fiabilitĂ© des datations Ă  partir des feldspaths potassiques. Un protocole de datation fondĂ© sur l’exploitation du signal de radioluminescence (IR-RF) de ces minĂ©raux a aussi Ă©tĂ© dĂ©veloppĂ©. Ainsi, la luminescence optique a Ă©tĂ© appliquĂ©e Ă  des Ă©chantillons provenant de six gisements de rĂ©fĂ©rence : Les Pradelles (Marillac, Charente), Combe Brune 2 (Creysse, Dordogne), Roc de Marsal (Campagne, Dordogne), Artenac (Saint-Mary, Charente), La Quina (Gardes-le-Pontaroux, Charente) et La Ferrassie (Savignac-de-Miremont, Dordogne). La combinaison des rĂ©sultats obtenus nous a permis, au sein de chaque niveau archĂ©ologique, d’évaluer la pertinence des datations et de proposer pour chaque gisement un scĂ©nario chronologique qui nous semble fiable. À l’issue de cette Ă©tude, les occupations humaines, caractĂ©risĂ©es selon leurs industries, ont pu ĂȘtre replacĂ©es sur une Ă©chelle des temps en regard des variations palĂ©oclimatiques et palĂ©oenvironnementales rĂ©gionales. Plusieurs constats ont Ă©tĂ© dressĂ©s enrichissant le registre de nos connaissances sur les cultures nĂ©andertaliennes.Currently available chronological information for Middle Palaeolithic sites in southwestern France precludes the establishment of a robust chronological framework. For these early periods, developing such a framework relies upon important methodological advancements in numerical dating techniques. The results of this study are essentially based on the optical luminescence dating of sedimentary feldspars and quartz. Focusing on the most commonly employed luminescence signals (IRSL, pIR-IRSL), it was possible to more clearly evaluate the reliability of dates obtained on K-feldspars. A dating protocol for these materials based on their radioluminescence signal (IR-RF) was also developed. Optical luminescence dates were produced for six major archaeological sites: (Marillac, Charente), Combe Brune 2 (Creysse, Dordogne), Roc de Marsal (Campagne, Dordogne), Artenac (Saint-Mary, Charente), La Quina (Gardes-le-Pontaroux, Charente) et La Ferrassie (Savignac-de-Miremont, Dordogne). Collating the results for each archaeological level allowed the coherence of the dates to be tested and a reliable chronological sequence to be proposed for each site. The different human occupations, characterised by their industrial attribution, could be placed within a chronological framework that incorporates regional palaeoenvironmental and palaeoclimatic variations. Finally, several observations provide new insights for our understanding of Neandertal cultures

    Evidence of shallow TL peaks contributions in infrared radiofluorescence

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    Assessing the dating potential of violet stimulated luminescence protocols

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    © 2019 M. Sontag-Gonzålez et al. publised by sciendo 2019. Violet stimulation is a new development in optical dating which has been suggested to extend the upper age limit of optically simulated luminescence (OSL) dating of quartz. Despite the reported advantage, few validation tests and applications have been published so far. The present study investigated the violet stimulated luminescence (VSL) using a single aliquot regenerative dose (SAR) protocol and a multiple aliquot additive dose (MAAD) protocol. Sedimentary quartz samples from four archaeological sites in Europe with independent age controls spanning 40-900 ka were used, including Grotte Mandrin (France), Brooksby Quarry (UK), Cueva Negra del Estrecho del Rió Quípar (Spain) and Sima de las Palomas del Cabezo Gordo (Spain). The equivalent dose of a relatively young sample (~40 ka) was successfully determined. However, significant underestimations were observed for older samples with higher doses. These findings indicate the need for further development of the measurement protocol to date high-dose natural samples
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