Norbert Mercier

Flint thermoluminescence dates from the CFR laboratory at Gif: Contributions to the study of the chronology of the middle palaeolithic

Abstract Flint tools are among the most durable objects marking the presence of prehistoric humans. Methodological advances of the last decade have made thermoluminescence of burnt flint a reliable dating tool and have provided new dates which require reassessment of the chronology of numerous Middle Palaeolithic sites. Dates for several Near Eastern sites show the presence of Neanderthals from at least oxygen isotope stage 6 until after 50 ka ago and push the appearance of modern humans to before 100 ka ago, long before their arrival in Europe. Whether the two populations were present continuously or intermittently and precisely when they appeared is uncertain at the moment. Thermoluminescence results suggest that the Mousterian lithic industries were introduced at about the same time in Europe as in the Near East, with the difference that in the latter area this industry was used by early modern humans as well as by Neanderthals. The new TL chronology assigns a much longer life-span to specific types of Levantine Mousterian lithic industries than previously believed. Finally, new dates for the Châtelperronian site of Saint-Cesaire open up the possibility that the last Neanderthals were still present after some Cro-Magnons had already settled in western Europe.

Dating the demise: neandertal extinction and the establishment of modern humans in the southern Caucasus.

This paper considers the recent radiometric dating (14C-AMS, TL, ESR) of 76 late Middle and early Upper Paleolithic samples from Ortvale Klde Rockshelter, located in the Republic of Georgia. We present a critical evaluation of each date based on its stratigraphic and archaeological context, its pretreatment and contamination history, and its resulting accuracy and precision, the goal being to establish a sound chronology for the site. Only by systematically identifying aberrant dates within a data set and isolating them from further analysis can we hope to understand cultural and biological phenomena on an accurate temporal scale. Based on the strict discard protocol outlined here, we omit 25% of the dated samples from the analysis. The remaining data speak to the lengthy tenure of Neandertals in the region, but also to their relatively rapid demise and the establishment of modern human populations approximately 38-34 ka 14C BP (42-39 kacalBP(Hulu)). We compare these chronometric data with those from the neighboring sites of Bronze and Dzudzuana caves, as well as Mezmaiskaya Cave, located in the northern Caucasus. While the lack of key contextual information limit our ability to subject these other data sets to the same critical evaluation procedure, they provide the first interregional temporal assessment of the Middle to Upper Paleolithic transition, the results of which suggest an initial expansion of modern humans into the southern Caucasus followed by expansion along the Black Sea coast and into the northern Caucasus.

Luminescence chronology of Pleistocene loess deposits from Romania: testing methods of age correction for anomalous fading in alkali feldspars

The IRSL dating method is applied to silt-sized alkali feldspar grains (40–60mm) from Upper and Middle Pleistocene loess deposits of southeastern Romania (sites of Tuzla and Giurgiu Malu-Rosu), using both the multiple aliquot g dose technique and the SAR method. All samples show evidence of anomalous fading; the measured IRSL ages are in correct stratigraphic order but systematically underestimate the expected geological age (up to 40%). Three protocols of age correction for the observed fading have been tested: the correction of Huntley and Lamothe (Can. J. Earth Sci. 38 (2001) 1093), the correction of Mejdahl (Quat. Sci. Rev. 7 (1988) 357) and the correction model suggested by Wintle (Quat. Sci. Rev. 9 (1990) 385). The three protocols yield corrected IRSL ages that are in better agreement with the expected ages. This study demonstrates the potential of the IRSL dating method to provide chronological information on Upper and Middle Pleistocene loess deposits of Romania. r 2003 Elsevier Science Ltd. All rights reserved.

TL dates for the Middle Paleolithic site of Combe-Capelle Bas, France

Abstract The Middle Paleolithic site of Combe-Capelle Bas, France, is known primarily from the excavations of Ami in the early part of the last century and more recently from the excavations of Dibble and Lenoir. Up to now, the only dates available for the site were based on geologic and paleoclimatic data. Most recently, Texier and Bertran suggest that the formation of the principal Mousterian deposits date to prior to OIS 6 and likely represent OIS 8 or even 10. The results of TL dating of burnt flints from these same deposits (Levels I-1D, I-1E, and I-2B), reported here, contradict this finding. They indicate an age of between 37 to 60 ka with six of the seven flints falling between 50–60 ka. This date fits well with Mousterian sites previously dated in this region of France.

Datation par thermoluminescence de la base du gisement paléolithique de Tabun (mont Carmel, Israël)

Abstract In this paper, we present new thermoluminescence dates for burnt flints from the lowest archaeological deposits of Tabun Cave (Mt. Carmel, Israel), which is often used as reference for all of Levant [3] , [11] . We discuss the impact of these dates on the chronostratigraphy and show that the uplift of Mt. Carmel (estimated at 10 cm·ka–1) might be responsible for some of the sedimentary collapses.

Flint palaeodose determination at the onset of saturation

Abstract To develop a satisfactory procedure for measuring the palaeodose of burnt flints showing signs of saturation, simulation experiments were performed on seven geological flints which were heated and irradiated in the laboratory. Since the curve expressing thermoluminescent (TL) growth as a function of dose varied from sample to sample, it was not possible to derive a single function applicable to all cases. Hence, a new approach has been developed using two parabolic functions; it gave promising results when applied to the experimental flints.

Luminescence dates for the palaeolithic site of Piekary IIa (Poland) comparison between TL of burnt flints and OSL of a loess-like deposit

We report the thermoluminescence age-estimates for burnt flints excavated at the palaeolithic site of Piekary IIa and discuss attempts to date quartz grains extracted from the embedding deposit using the OSL technique with the SAR protocol. The results indicate that this loess-like deposit contains a mixture of grains, well bleached at different periods in the past, and that the study of small aliquots seems to be the only way to discriminate between the different fractions.

TL dating of Upper Palaeolithic sites in the Coa Valley (Portugal)

Abstract In 1992, numerous animal engravings in styles associated with the Upper Palaeolithic (Gravetian to Magdalenian) were discovered along a long stretch of the schist cliffs bordering the Coa Valley (Northern Portugal). This suggested that not only caves and rock-shelters but also open-air Pleistocene sites may have been decorated in this manner more often than previously believed. Attempts to date the engravings themselves (radiocarbon of patination, micro-erosion analysis) were unsatisfactory, yielding contradictory and widely scattered dates. We are now reporting thermoluminescence ages of 15 burnt quartzite pebbles excavated in 1997 at three sites (Cardina, Olga Grande Sul, Quinta da Barca Sul) near the decorated cliffs. The ages of the Cardina and Olga Grande Sul pebbles indicated human presence at the sites between 30 and 27 ka ago, during the Gravetian period. The Quinta da Barca Sul pebbles were 13–10xa0ka old, indicating that humans were also present in the Valley during the Magdalenian period.

Chronologie K–Ar et TL du volcanisme aux extrémités sud du propagateur mer Rouge en Afar depuis 300 ka

K-Ar and TL volcanism chronology of the southern ends of the Red Sea spreading in Afar since 300 ka. Continental rift segments linked to the propagation of the Red Sea plate boundary in Afar are dated using thermoluminescence and potassium-argon dating techniques. These new results constrain the mechanism of the two moderate extensional structures located at the southern ends of the propagator: the Manda Hararo and the Dadar graben. Ages obtained show that their internal floor are about 30 and 100 kyr old, respectively, and that the deduced vertical rate of fault scarps display values lower than those linked to the Gulf of Aden propagation. The lower deformation accommodated by the Red Sea structures, their youthfulness and the greater distance to the mature oceanic ridges could justify this contrast of evolution. uf6d9 2001 Academie des sciences / Editions scientifiques et medicales Elsevier SAS K-Ar dating / thermoluminescence / Afar / rifting / Red Sea / Ethiopia

Attempt at using the single-aliquot regenerative-dose procedure for the determination of equivalent doses of Upper Palaeolithic burnt stones.

The equivalent dose of Upper Palaeolithic quartzite pebbles burnt in prehistoric hearths was determined using the optically stimulated luminescence (OSL) signal and the single-aliquot regenerative-dose (SAR) procedure. Since previously published thermoluminescence (TL) dates for these samples were in agreement with the archaeological record and other chronological data, the TL equivalent doses were used as a reference. The observed discrepancies between some TL and OSL SAR equivalent doses are probably due to accidental bleaching before the stones reached the laboratory, instead of reflecting a deficiency of the SAR procedure. This hypothesis is confirmed by experiments which indicate that bleaching could reach considerable depths in quartzite specimens and significantly deplete the OSL signal.