993 resultados para Maya chronology.


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This paper outlines the results of a programme of radiocarbon dating and Bayesian modelling relating to an Early Bronze Age barrow cemetery at Over, Cambridgeshire. In total, 43 dates were obtained, enabling the first high-resolution independent chronology (relating to both burial and architectural events) to be constructed for a site of this kind. The results suggest that the three main turf-mound barrows were probably constructed and used successively rather than simultaneously, that the shift from inhumation to cremation seen on the site was not a straightforward progression, and that the four main ‘types’ of cremation burial in evidence were used throughout the life of the site. Overall, variability in terms of burial practice appears to have been a key feature of the site. The paper also considers the light that the fine-grained chronology developed can shed on recent much wider discussions of memory and time within Early Bronze Age barrows

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The date of the Late Bronze Age Minoan eruption of the Thera volcano has provoked much debate among archaeologists, not least in a recent issue of Antiquity (‘Bronze Age catastrophe and modern controversy: dating the Santorini eruption’, March 2014). Here, the authors respond to those recent contributions, citing evidence that closes the gap between the conclusions offered by previous typological, stratigraphic and radiometric dating techniques. They reject the need to choose between alternative approaches to the problem and make a case for the synchronisation of eastern Mediterranean and Egyptian chronologies with agreement on a ‘high’ date in the late seventeenth century BC for the Thera eruption.

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A pre-requisite for understanding the transition to the Neolithic in the Levant is the establishment of a robust chronology, most notably for the late Epi-Palaeolithic and Pre-Pottery Neolithic A (PPNA) periods. In this contribution we undertake a dating analysis of the Pre-Pottery Neolithic site of WF16, southern Jordan, drawing on a sample of 46 AMS 14C dates. We utilise Bayesian methods to quantify an old wood effect to provide an offset that we factor into chronological models for a number of individual structures at WF16 and for the settlement as a whole. In doing so we address the influence of slope variations in the calibration curve and expose the significance of sediment and sample redeposition within sites of this nature. We conclude that for the excavated deposits at WF16 human activity is likely to have started by c. 11.84 ka cal bp and lasted for at least c. 1590 years, ceasing by c. 10.24 ka cal bp. This is marked by a particularly intensive period of activity lasting for c. 350 years centred on 11.25 ka cal bp followed by less intensive activity lasting a further c. 880 years. The study reveals the potential of WF16 as a laboratory to explore methodological issues concerning 14C dating of early Neolithic sites in arid, erosional environments.

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We used the fabrics of two granite plutons and U/Pb (SHRIMP) zircon ages to constrain the tectonic evolution of the E-trending Patos shear zone (Borborema Province, NE Brazil). The pre-tectonic Teixeira batholith consists of an amphibole leucogranite locally with aegirine-augite. Zircons from a syenogranite yielded crystallization ages of 591 +/- 5 Ma. The batholith fabrics were determined by anisotropy of magnetic susceptibility (AMS) and mineral shape preferred orientation. The fabrics support pre-transcurrent batholith emplacement, as evidenced by: (i) magmatic/magnetic fabrics in low susceptibility (<0.35 mSI) leucogranites highly discordant to the regional host rock structure, and (ii) concordant magnetic fabrics restricted to high susceptibility (>1 mSI) corridors connected to shear zones branching off from Patos. One of these satellite shear zones controlled the syntectonic emplacement of the Serra Redonda pluton, which yields a crystallization age of 576 +/- 3 Ma. This late shearing event marks the peak regional deformation that, south of Patos, was coupled to crustal shortening nearly perpendicular to the shear belt. The chronology of the deformational events indicates that the major shear zones of the eastern Borborema are late structures active after the crustal blocks amalgamated. (C) 2007 Elsevier Ltd. All rights reserved.

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Past studies have evidenced the presence of charcoal in soils and lacustrine sediments of Amazonia region and suggested occurrences of widespread fires during the Middle Holocene. However, the available records do not indicate the changes in fire regime with enough time resolution. We quantified charcoal fragments in lacustrine sediments in a lake of North Carajas plateau in East Amazonia (5 degrees 50`-6 degrees 35`S and 49 degrees 30`-52 degrees 00`W). The charcoal quantification was compared to other sediment proxies, allowing a connection between paleofires and climate changes. Large variations in sediment characteristics led to distinct stages of sedimentation. From 11,800 (base of CSN 93/4) to 4750 cal yr B.P., low accumulation rates of organic matter are observed. Between 7600 cal yr B.P. (base of CSN 93/3 core) and 4750 cal yr B.P., this initial phase of sedimentation is characterized by low chlorophyll derivate accumulation rates and high accumulation rates of Botryococcus braunii, an alga resistant to episodic drought. The first phase of sedimentation would therefore correspond to, a low take level and a drier climate than today. Large biomass burning events occurred between 7450 cal yr B.P. and 4750 cal yr B.P., as indicated by the high charcoal particle concentration. From 4750 cal yr B.P. to 2800 cal yr B.P., accumulation rates of charcoal particles decreased, and the accumulation rate of chlorophyll derivate was low. From 2800 cal yr B.P. to 1300 cal yr B.P., the charcoal accumulation rates reached their lowest values in the core and a rapid increase in lacustrine production is evidenced by the increase in chlorophyll derivates and carbon accumulation rate. From 1300 cal yr B.P. to the last century, the charcoal accumulation rates increased. During the most recent period, the record is characterized by high accumulation rates of chlorophyll derivates while the charcoal particle accumulation rate decreased. This region is still unaffected by the current increase of anthropogenic fires. (c) 2007 Elsevier B.V. All rights reserved.

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A silent video that Steph O'Hara, composer and musician has composed a sound trace for live presentation

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