Plio-Quaternary coastal uplift along the western Iberian margin: insights from dated marine terraces (Peniche, central Portugal)

This study provides a detailed geomorphological study of the Peniche Peninsula, located in westernmost Iberia, a resistant rocky limestone headland subjected to high energy Atlantic Ocean coastal processes. We have used field mapping, surveying, sedimentary facies analysis, geochronology (electron spin resonance [ESR]; U-Series), but also identification of fossils and lithic artefacts, in order to: 1) reconstruct styles and timing of paleoenvironmental changes, 2) correlate to Marine Isotope Stages (MIS), and 3) quantify coastal uplift rates during the Quaternary. The marine terrace deposits, comprising calcite cemented conglomerates and siliciclastic sandstones, sometimes capped by travertines, were studied in detail along the SW sector of the peninsula, at the Furninha Cave site. The mapping (1/10,000 scale) and dating results obtained allow to identify several marine levels and to correlate them to MIS’s: 1) a culminant wave-cut platform at 29-33 m (above mean sea level) (Pm), with a probable age of 3.7 Ma; 2) a wave-cut platform at 24-28 m (Tm1), dated as 883±120 ka, probably correlated with high sea level conditions spanning ca.1000-790 ka (MIS25-19); 3) a wave-cut platform at 19-21 m (Tm2), with a beach conglomerate and sandstone, dated as 707±32 ka and correlated to 790-680 ka (MIS17); 4) a wave-cut platform at 14-16 m (Tm3), with a beach conglomerate and sandstone, and capping travertine, probably recording aggradation during 620-460 ka (MIS15-13) (ESR: 598±160, 563±63, 490±44 ka; U-series: >620 ka); 5) a wave-cut platform at 11-13 m (Tm4), with beach conglomerate and sandstone followed by travertine, dated as 315±48 ka, probably recording 430-275 ka (MIS11-9); 6) a wave-cut platform at 6-9 m (Tm5), with beach conglomerate, sandstone and travertine, dated as 288±53 ka, probably spanning 290-180 ka (MIS7); 7) a wave-cut platform at 4.0 m (Tm6), probably spanning 125-85 ka (MIS5); 8) aeolian sand units, respectively, of Late Pleistocene and Holocene age; 9) modern beach sediments, ranging from sands to boulders. A long term Plio-Quaternary corrected uplift rate of 0.004-0.006 m/ka is obtained using the Pm level as a key geomorphic marker (eustatic level = +10-20 m). In contrast, for the last ~1 Ma the inset Pleistocene marine terrace levels (Tm1-Tm6) indicate apparent short-term uplift rates between 0.02 and 0.05 m/ka (means of 0.03 to 0.04 m/ka) and corrected short-term uplift rates between -0.05 and 0.05 m/ka (means of -0.02 to 0.05 m/ka). This study demonstrates that the Quaternary compressive reactivation of the Western Iberian Margin has determined coastal low to moderate uplift rates; active tectonics play an important role in the geomorphic expression and distribution of Pleistocene marine terraces, recording vertical ground motions (uplift/subsidence) superimposed onto global sea-level oscillations

Can we identify the Mexican hairless dog in the archaeological record? Morphological and genetic insights from Tizayuca, Basin of Mexico

The Mexican Hairless dog, or Xoloitzcuintle, is a breed characterised by a sparse hair coat and a severe oligodontia. This phenotype is a consequence of Canine Ectodermal Dysplasia (CED) caused by a mutation on the FoxI3 autosomal gene. First accounts of hairless dogs in Mexico are dated to the 16th century CE, according to the historical record, but pre-Hispanic dog skeletons presenting missing and abnormally shaped teeth have been interpreted as earlier evidence of hairless dogs. However, several questions remain unanswered regarding the timing of apparition of this phenotype and its relationship with modern hairless breeds. In this paper, we review the morphological characteristics of potential hairless dogs and we apply ancient mitochondrial DNA analyses along with radiocarbon dating to eight archaeological dog mandibles from Tizayuca, Basin of Mexico, presenting anomalies that could be attributed to a CED. The archaeological dogs were dated between 1620 and 370 years BP. Among these eight individuals, we identify four different mitochondrial haplotypes including two novel haplotypes. The dogs from the Basin of Mexico display a very high genetic diversity and continuity from the Classic to the Postclassic. However, our attempt at amplifying the FoxI3 mutation was unsuccessful. Finally, we show that some haplotypes are present in both archaeological dogs and modern hairless breeds, perhaps reflecting their maternal ancestry

Identification génétique et datation radiocarbone de restes osseux de cerf, de renne et de bison des steppes d’une sépulture moustérienne (La Ferrassie 8, Dordogne, France)

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GG (Gas Graphitisation) : un banc de graphitisation polyvalent et évolutif, complémentaire d’AGE3 pour ECHoMICADAS

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La datation ESR/U-Th de restes paléontologiques,un outil pour estimer le possible remaniementdes niveaux archéologiques ?

La datation par ESR/U-Th de restes paléontologiques est une méthode paléodosimétrique couramment utilisée pour dater des niveaux archéologiques du Pléistocène moyen et supérieur. Au-delà de l’apport purement géochronologique (c’est souvent l’une des rares méthodes utilisables sur des gisements hors contextes volcanique ou karstique) et malgré des incertitudes parfois importantes sur les âges obtenus (10-15 %, en raison du grand nombre de variables – plus de 25 – pouvant entrer dans le calcul d’un âge), la méthode peut généralement permettre, en appui des données stratigraphiques et paléoenvironnementales disponibles, d’attribuer les niveaux archéologiques étudiés à un stade isotopique marin (MIS) donné, voire à un sous-stade, si la dosimétrie environnementale de l’échantillon est raisonnablement bien décrite. Cependant, pour certains gisements, les résultats obtenus montrent une disparité d’âge qui dépasse largement les variations locales de dosimétrie observées dans la couche étudiée. Ceci pourrait alors indiquer un mélange de stocks paléontologiques d’âges différents ou que des dents, à l’histoire dosimétrique différente de celles correspondant réellement à l’occupation humaine que l’on cherche à dater, pourraient être présentes dans les niveaux correspondants.ESR/U-series dating of fossil teeth is a palaeodosimetric method commonly used for Middle and Late Pleistocene archaeological levels. Beyond the geochronological interest (it is often one of the few methods applicable on sites located in non-volcanic or carbonated areas) and despite the relatively important age uncertainties (usually 10-15 %, because of the high number of parameters – over 25 – considered in the age calculation process), ESR/U-series method can allow, in combination with the available stratigraphic and palaeoenvironmental data, the correlation of the studied archaeological levels to a specific marine isotopic (MIS), if the evolution of the dose rate with time since the sample burial is reasonably well described. However, for some sites the results display great age scatter ages that could simply not be explained by local variations of the dose rate for the studied level. It could indicate instead that the palaeontological record is made by several stocks of different ages ordosimetric histories mixed in the same archaeological level

Biogenic and diagenetic indicators in archaeological and modern otoliths: Potential and limits of high definition synchrotron micro-XRF elemental mapping

International audienceFish otoliths are biogeochemical archives of environmental conditions and are a valuable tool for examining life traits. These sclerochronological life history records, accessed through geochemical analyses, are widely used in fisheries sciences, and are seeing growing use as palaeoenvironmental archives or for reconstruction of past human activities. The fidelity of such reconstructions relies on the preservation of the biogenic geochemistry, which may be altered through diagenetic processes. In this work, a methodology is provided that enables measurement of elemental concentrations with a high precision with simultaneous quality control of the data to ensure high reliability and a multi-technique sample marking strategy to ensure precise alignment. Thin sections of four archaeological and two modern otoliths from the Pacific coast of South America were examined by synchrotron mu XRF. High-definition elemental maps of sample sections up to 3.2 x 1.0 mm(2) (V x H) were produced with an on-sample spot size of 6.0 x 16 mu m(2). Thirteen elementswere detected, some of which may be useful indicators of diagenetic alteration. Strontium was accurately quantified and one sample presented local concentrations above the previously described range in literature. The quantity of collected data allows the use of statistical approaches to examine the intra- and inter-sample Sr distribution. A highly reliable profile, produced by integrating multiple points, additionally permits identification of defects and potential alteration along its length through changes in median absolute deviation. Contamination at the edge of some of the specimens was evidenced from preparation and other post-mortem alterations, even in modern samples, however diagenetic alteration in the elemental signals was not evidenced significantly further than a few hundred micrometres deep in the samples. Medium-energy SR-mu XRF therefore provides a fast and sensitive elemental probe without a visible effect on the sample, and the integration volume which limits the attainable lateral resolution in this energy range is discussed. This paper discusses the methodological limitations and opens new perspectives in the analysis of biomineral carbonate palaeoproxies. (C) 2015 Elsevier B.V. All rights reserved

ESR and ESR/U-series dating of several Middle Pleistocene Italian sites: a comparison with 40Ar/39Ar chronology

International audienceThe stratigraphic sequences of numerous palaeolithic sites of Central and Southern Italy, very rich in both archaeological and palaeontological remains, have recorded volcanic events allowing the comparison of the chronologies derived from ESR and ESR/U-series analyses on fluvial bleached quartz and tooth enamel respec-tively with the chronological framework obtained by 40Ar/39Ar dating method on single volcanic K-feldspar crystals. Since 2009, several Middle Pleistocene sites including volcanic and archaeological levels were studied (from the west to the east): La Polledrara di Cecanibbio, Isoletta, (Lazio), Guado San Nicola, Isernia La Pineta (Molise) and Venosa Notarchirico (Basilicata). The obtained results, that cover the time range between 660 and 350 ka, will be displayed and discussed. They indicate that the multi-method approach is useful to constrain the chronology of each site and that the application of every method have specific limitations due to the geological background (for ESR, the lack of quartz grains in some areas and for ESR/U-series complex U-uptake histories in others places). Despite these limitations, the ESR and ESR/U-series framework is globally in agreement with the 40Ar/39Ar chronology

Etude chronologique intégrée de sites paléoanthropologiques pléistocènes du Hubei occidental et de la région des Trois Gorges

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