965 resultados para Quartz dating
Resumo:
Le site Gaudreau est un site perturbé et à occupations multiples situé dans le sud-est du Québec, et présente des occupations datant du Paléoindien Récent jusqu’à la période historique. Les occupations Archaïques du site, noté par la présence de bifaces diagnostiques de l’Archaïque Supérieur et de l’Archaïque Terminal et par des Macrooutils de l’Archaïque Moyen et de l’Archaïque Supérieur, sont le sujet principal de ce mémoire. Puisqu’aucune occupation ne peut être différencié horizontalement ni verticalement, et qu’aucun objet non-diagnostique ne peut être associé avec certitude, seul un échantillon de 32 objets ont été observés. Étant donné la faible taille de l’échantillon analysé, il est fort probable qu’un plus grand nombre de sources de matières premières aient été utilisés durant les occupations de l’Archaïque. Toutefois, un réseau de matières premières lithiques similaire à ceux des sites du Lac Mégantic a été observé, avec une forte représentation de la rhyolite Kineo-Traveller et des cherts Appalachiens. Des cherts des Grands Lacs et le quartzite de Cheshire sont aussi présents. Le mudstone silicifié d’origine locale et le quartz sont par contre faiblement représentés dans l’échantillon, probablement dû à un biais de proximité de source. L’analyse technique de l’échantillon, sans contrôle pour les pratiques techno-économiques, dénote plusieurs récurrences techniques à l’intérieur des unités typologiques, sans toutefois appuyer des différences récurrentes significatives entre les matières premières de régions différentes. À cause de la taille de l’échantillon et du contexte perturbé, la pertinence des fortes similarités entre certains objets est douteuse. La segmentation interpersonnelle des chaînes opératoires ne pouvait être déterminée dans l’échantillon. Cependant, les résultats incitent plutôt à croire que les matières premières devaient circuler sous diverses formes. Il peut être considéré que, en dehors des matières premières locales, les occupants Archaïques du site Gaudreau n’avaient pas d’accès direct aux matières premières exogènes.
Resumo:
Le site Gaudreau est un site perturbé et à occupations multiples situé dans le sud-est du Québec, et présente des occupations datant du Paléoindien Récent jusqu’à la période historique. Les occupations Archaïques du site, noté par la présence de bifaces diagnostiques de l’Archaïque Supérieur et de l’Archaïque Terminal et par des Macrooutils de l’Archaïque Moyen et de l’Archaïque Supérieur, sont le sujet principal de ce mémoire. Puisqu’aucune occupation ne peut être différencié horizontalement ni verticalement, et qu’aucun objet non-diagnostique ne peut être associé avec certitude, seul un échantillon de 32 objets ont été observés. Étant donné la faible taille de l’échantillon analysé, il est fort probable qu’un plus grand nombre de sources de matières premières aient été utilisés durant les occupations de l’Archaïque. Toutefois, un réseau de matières premières lithiques similaire à ceux des sites du Lac Mégantic a été observé, avec une forte représentation de la rhyolite Kineo-Traveller et des cherts Appalachiens. Des cherts des Grands Lacs et le quartzite de Cheshire sont aussi présents. Le mudstone silicifié d’origine locale et le quartz sont par contre faiblement représentés dans l’échantillon, probablement dû à un biais de proximité de source. L’analyse technique de l’échantillon, sans contrôle pour les pratiques techno-économiques, dénote plusieurs récurrences techniques à l’intérieur des unités typologiques, sans toutefois appuyer des différences récurrentes significatives entre les matières premières de régions différentes. À cause de la taille de l’échantillon et du contexte perturbé, la pertinence des fortes similarités entre certains objets est douteuse. La segmentation interpersonnelle des chaînes opératoires ne pouvait être déterminée dans l’échantillon. Cependant, les résultats incitent plutôt à croire que les matières premières devaient circuler sous diverses formes. Il peut être considéré que, en dehors des matières premières locales, les occupants Archaïques du site Gaudreau n’avaient pas d’accès direct aux matières premières exogènes.
Resumo:
NEW DATA ON THE CHRONOLOGY OF THE VALE DO FORNO SEDIMENTARY SEQUENCE (LOWER TAGUS RIVER TERRACE STAIRCASE) AND ITS RELEVANCE AS FLUVIAL ARCHIVE OF THE MIDDLE PLEISTOCENE IN WESTERN IBERIA Pedro P. Cunha 1, António A. Martins 2, Jan-Pieter Buylaert 3,4, Andrew S. Murray 4, Luis Raposo 5, Paolo Mozzi 6, Martin Stokes 7 1 MARE - Marine and Environmental Sciences Centre, Department of Earth Sciences, University of Coimbra, Portugal: pcunha@dct.uc.pt 2 MARE - Marine and Environmental Sciences Centre, Dep. Geociências, University of Évora, Portugal; aam@uevora.pt 3 Centre for Nuclear Technologies, Technical University of Denmark, Risø Campus, Denmark; jabu@dtu.dk 4 Nordic Laboratory for Luminescence Dating, Aarhus University, Risø DTU, Denmark; anmu@dtu.dk 5 Museu Nacional de Arqueologia, Lisboa, Portugal; 3raposos@sapo.pt 6 Department of Geosciences, University of Padova, Italy; paolo.mozzi@unipd.it 7 School of Geography, Earth and Environmental Sciences, University of Plymouth, UK; m.stokes@plymouth.ac.uk The stratigraphic units that record the evolution of the Tagus River in Portugal (study area between Vila Velha de Ródão and Porto Alto villages; Fig. 1) have different sedimentary characteristics and lithic industries (Cunha et al., 2012): - a culminant sedimentary unit (the ancestral Tagus, before the drainage network entrenchment) – SLD13 (+142 to 262 m above river bed – a.r.b.; with probable age ca. 3,6 to 1,8 Ma), without artefacts; - T1 terrace (+84 to 180 m; ca. 1000? to 900 ka), without artefacts; - T2 terrace (+57 to 150 m; top deposits with a probable age ca. 600 ka), without artefacts; - T3 terrace (+43 to 113 m; ca. 460 to 360? ka), without artefacts; - T4 terrace (+26 to 55 m; ca. 335 a 155 ka), Lower Paleolithic (Acheulian) at basal and middle levels but early Middle Paleolithic at top levels; - T5 terrace (+5 to 34 m; 135 to 73 ka), Middle Paleolithic (Mousterian; Levallois technique); - T6 terrace (+3 to 14 m; 62 to 32 ka), late Middle Paleolithic (late Mousterian); - Carregueira Sands (aeolian sands) and colluvium (+3 a ca. 100 m; 32 to 12 ka), Upper Paleolithic to Epipaleolithic; - alluvial plain (+0 to 8 m; ca. 12 ka to present), Mesolithic and more recent industries. The differences in elevation (a.r.b.) of the several terrace staircases results from differential uplift due to active faults. Longitudinal correlation with the terrace levels indicates that a graded profile ca. 200 km long was achieved during terrace formation periods and a strong control by sea base level was determinant for terrace formation. The Neogene sedimentary units constituted the main source of sediments for the fluvial terraces (Fig. 2). Geomorphological mapping, coupled with lithostratigraphy, sedimentology and luminescence dating (quartz-OSL and K-feldspar post-IRIR290) were used in this study focused on the T4 terrace, which comprises a Lower Gravels (LG) unit and an Upper Sand (US) unit. The thick, coarse and dominantly massive gravels of the LG unit indicate deposition by a coarse bed-load braided river, with strong sediment supply, high gradient and fluvial competence, during conditions of rapidly rising sea level. Luminescence dating only provided minimum ages but it is probable that the LG unit corresponds to the earlier part of the MIS9 (ca. 335 to 325 ka), immediately postdating the incision promoted by the very low sea level (reaching ca. -140 m) during MIS10 (362 to 337 ka), a period of relatively cold climate conditions with weak vegetation cover on slopes and low sea level. Fig. 1. Main Portuguese reaches in which the Tagus River can be divided (Lower Tagus Basin): I – from the Spanish border to Arneiro (a general E–W trend, mainly consisting of polygonal segments); II – from Arneiro to Gavião (NE–SW); III – from Gavião to Arripiado (E–W); IV – from Arripiado to Vila Franca de Xira (NNE-SSW); V – from Vila Franca de Xira to the Atlantic shoreline. The faults considered to be the limit of the referred fluvial sectors are: F1 – Ponsul-Arneiro fault (WSW-ENE); F2 – Gavião fault (NW-SE); F3 – Ortiga fault (NW-SE); F4 – Vila Nova da Barquinha fault (W-E); F5 – Arripiado-Chamusca fault (NNE-SSW). 1 – estuary; 2 – terraces; 3 – faults; 4 – Tagus main channel. The main Iberian drainage basins are also represented (inset). The lower and middle parts of the US unit, comprising an alternation of clayish silts with paleosols and minor sands to the east (flood-plain deposits) and sand deposits to the west (channel belt), have a probable age of ca. 325 to 200 ka. This points to formation during MIS9 to MIS7, under conditions of high to medium sea levels and warm to mild conditions. The upper part of the US unit, dominated by sand facies and with OSL ages of ca. 200 to 154 ka, correlates with the early part of the MIS6. During this period, progradation resulted from climate deterioration and relative depletion of vegetation that promoted enhanced sediment production in the catchment, coupled with initiation of sea-level lowering that increased the longitudinal slope. The Vale do Forno and Vale da Atela archaeological sites (Alpiarça, central Portugal) document the earliest human occupation in the Lower Tagus River, well established in geomorphological and environmental terms, within the Middle Pleistocene. The Lower Palaeolithic sites were found on the T4 terrace (+26 m, a.r.b.). The oldest artefacts previously found in the LG unit, display crude bifacial forms that can be attributed to the Acheulian, with a probable age of ca. 335 to 325 ka. The T4 US unit has archaeological sites stratigraphically documenting successive phases of an evolved Acheulian, that probably date ca. 325 to 300 ka. Notably, these Lower Palaeolithic artisans were able to produce tools with different sophistication levels, simply by applying different strategies: more elaborated reduction sequences in case of bifaces and simple reduction sequences to obtain cleavers. Fig. 2. . Simplified geologic map of the Lower Tagus Cenozoic basin, adapted from the Carta Geológica de Portugal, 1/500000, 1992). The study area (comprising the Vale do Forno and Vale de Atela sites) is located on the more upstream sector of the Lower Tagus River reach IV, between Arripiado and Chamusca villages. 1 – alluvium (Holocene); 2 – terraces (Pleistocene); 3 – sands, silts and gravels (Paleogene to Pliocene); 4 – Sintra Massif (Cretaceous); 5 – limestones, marls, silts and sandstones (Mesozoic); 6 – quartzites (Ordovician); 7 – basement (Proterozoic to Palaeozoic); 8 – main fault. The main Portuguese reaches of the Tagus River are identified (I to V). The VF3 site (Milharós), containing a Final Acheulian industry, with fine and elaborated bifaces) found in a stratigraphic level located between the T4 terrace deposits and a colluvium associated with Late Pleistocene aeolian sands (32 to 12 ka), has an age younger than ca. 154 ka but much older than 32 ka. In the study area, the sedimentary units of the T4 terrace seem to record the river response to sea-level changes and climatically-driven fluctuations in sediment supply. REFERENCES Cunha P. P., Almeida N. A. C., Aubry T., Martins A. A., Murray A. S., Buylaert J.-P., Sohbati R., Raposo L., Rocha L., 2012, Records of human occupation from Pleistocene river terrace and aeolian sediments in the Arneiro depression (Lower Tejo River, central eastern Portugal). Geomorphology, vol. 165-166, pp. 78-90.
Resumo:
A low temperature synthesis method based on the decomposition of urea at 90°C in water has been developed to synthesise fraipontite. This material is characterised by a basal reflection 001 at 7.44 Å. The trioctahedral nature of the fraipontite is shown by the presence of a 06l band around 1.54 Å, while a minor band around 1.51 Å indicates some cation ordering between Zn and Al resulting in Al-rich areas with a more dioctahedral nature. TEM and IR indicate that no separate kaolinite phase is present. An increase in the Al content however, did result in the formation of some SiO2 in the form of quartz. Minor impurities of carbonate salts were observed during the synthesis caused by to the formation of CO32- during the decomposition of urea.
Resumo:
Raman spectroscopic analyses of fragmented wall-painting specimens from a Romano-British villa dating from ca. 200 AD are reported. The predominant pigment is red haematite, to which carbon, chalk and sand have been added to produce colour variations, applied to a typical Roman limewash putty composition. Other pigment colours are identified as white chalk, yellow (goethite), grey (soot/chalk mixture) and violet. The latter pigment is ascribed to caput mortuum, a rare form of haematite, to which kaolinite (possibly from Cornwall) has been added, presumably in an effort to increase the adhesive properties of the pigment to the substratum. This is the first time that kaolinite has been reported in this context and could indicate the successful application of an ancient technology discovered by the Romano-British artists. Supporting evidence for the Raman data is provided by X-ray diffraction and SEM-EDAX analyses of the purple pigment.
Resumo:
The Architecture, Disciplinarity and the Arts symposium was organised by the Architecture. Theory, Criticism and History (ATCH) research group at the University of Queensland, run by John Macarthur and Antony Moulis, together with Andrew Leach who joined them last year and organised much of the symposium. The symposium ran for three days in a small room at the Institute of Modern Art (IMA) in Fortitude Valley, Brisbane (generously donated by director Robert Leonard), with about 40 people in attendance. Together with a long question time of an hour after every three speakers, the size of the room and the small number of people made it very different from most architecture or design conferences. The intellectual level of the symposium was high, without the speed dating aspect that one often sees at the Society of Architectural Historians, Australia and New Zealand (SAHANZ) meetings, where endless parallel sessions of short papers create an occasionally disorientating cacophony of words. The symposium was deliberately, unapologetically academic and the intimate nature of the forum made the discussion rich and collaborative, with an active audience. The title of the symposium, 'Architecture, Disciplinarity and the Arts', reflects the connection that already exists between the art history and the architectural history community in Brisbane, with both groups regularly attending each other's functions.
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Live-collected samples of four common reef building coral genera (Acropora, Pocillopora, Goniastrea, Porites) from subtidal and intertidal settings of Heron Reef, Great Barrier Reef, show extensive early marine diagenesis where parts of the coralla less than 3 years old contain abundant macro- and microborings and aragonite, high-Mg calcite, low-Mg calcite, and brucite cements. Many types of cement are associated directly with microendoliths and endobionts that inhabit parts of the corallum recently abandoned by coral polyps. The occurrence of cements that generally do not precipitate in normal shallow seawater (e.g., brucite, low-Mg calcite) highlights the importance of microenvironments in coral diagenesis. Cements precipitated in microenvironments may not reXect ambient seawater chemistry. Hence, geochemical sampling of these cements will contaminate trace-element and stable-isotope inventories used for palaeoclimate and dating analysis. Thus, great care must be taken in vetting samples for both bulk and microanalysis of geochemistry. Visual inspection using scanning electron microscopy may be required for vetting in many cases.
Resumo:
Raman spectroscopy and FT-IR imaging analyses of cave wall pigment samples from north Queensland (Australia) indicate that some hand stencils were undertaken during a dry environmental phase indicating late Holocene age. Other, earlier painting episodes also took place during dry environmental periods of the terminal Pleistocene and/or early Holocene. These results represent a rare opportunity to attain chronological information for rock art in conditions where insufficient carbon is present for radiocarbon dating.
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This thesis is a study of naturally occurring radioactive materials (NORM) activity concentration, gamma dose rate and radon (222Rn) exhalation from the waste streams of large-scale onshore petroleum operations. Types of activities covered included; sludge recovery from separation tanks, sludge farming, NORM storage, scaling in oil tubulars, scaling in gas production and sedimentation in produced water evaporation ponds. Field work was conducted in the arid desert terrain of an operational oil exploration and production region in the Sultanate of Oman. The main radionuclides found were 226Ra and 210Pb (238U - series), 228Ra and 228Th (232Th - series), and 227Ac (235U - series), along with 40K. All activity concentrations were higher than the ambient soil level and varied over several orders of magnitude. The range of gamma dose rates at a 1 m height above ground for the farm treated sludge had a range of 0.06 0.43 µSv h 1, and an average close to the ambient soil mean of 0.086 ± 0.014 µSv h 1, whereas the untreated sludge gamma dose rates had a range of 0.07 1.78 µSv h 1, and a mean of 0.456 ± 0.303 µSv h 1. The geometric mean of ambient soil 222Rn exhalation rate for area surrounding the sludge was mBq m 2 s 1. Radon exhalation rates reported in oil waste products were all higher than the ambient soil value and varied over three orders of magnitude. This study resulted in some unique findings including: (i) detection of radiotoxic 227Ac in the oil scales and sludge, (ii) need of a new empirical relation between petroleum sludge activity concentrations and gamma dose rates, and (iii) assessment of exhalation of 222Rn from oil sludge. Additionally the study investigated a method to determine oil scale and sludge age by the use of inherent behaviour of radionuclides as 228Ra:226Ra and 228Th:228Ra activity ratios.
Resumo:
How interactive new media art can effectively communicate an indigenous philosophical concept. The sophistication and complexity of the philosophical concept concerning relationships between land and people and between people, intrinsic to the laws and customs of Australian Indigenous society, has begun to be communicated and accessed beyond the realm of anthropological and ethnological domains of Western scholarship. The exciting scope and rapid development of new media arts presents an innovative means of creating an interactive relationship with the general Australian public, addressing the urgent need for an understanding of Indigenous Australian concepts of relationship to land, and to each other, absent from Western narratives. The study is framed by an Indigenous concept of place, and relationships between land and people and between people; and explores how this concept can be clearly communicated through interactive new media arts. It involves: a creative project, the development of an interactive new media art project, a website work-in-progress titled site\sight\cite; and an exegesis, a Novella of Ideas, on the origins, influences, objectives, and potential of creative practices and processes engaged in the creative project. Research undertaken for the creative project and exegesis extended my creative practice into the use of interdisciplinary arts, expressly for the expression of philosophical concepts, consolidating 23 years experience in Indigenous community arts development. The creative project and exegesis contributes to an existing body of Indigenous work in a range of areas - including education, the arts and humanities - which bridges old and new society in Australia. In this study, old and new society is defined by the time of the initial production of art and foundations of knowledge, in the country of its origins, in Indigenous Australia dating back at least 40,000 years.
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The value of soil evidence in the forensic discipline is well known. However, it would be advantageous if an in-situ method was available that could record responses from tyre or shoe impressions in ground soil at the crime scene. The development of optical fibres and emerging portable NIR instruments has unveiled a potential methodology which could permit such a proposal. The NIR spectral region contains rich chemical information in the form of overtone and combination bands of the fundamental infrared absorptions and low-energy electronic transitions. This region has in the past, been perceived as being too complex for interpretation and consequently was scarcely utilized. The application of NIR in the forensic discipline is virtually non-existent creating a vacancy for research in this area. NIR spectroscopy has great potential in the forensic discipline as it is simple, nondestructive and capable of rapidly providing information relating to chemical composition. The objective of this study is to investigate the ability of NIR spectroscopy combined with Chemometrics to discriminate between individual soils. A further objective is to apply the NIR process to a simulated forensic scenario where soil transfer occurs. NIR spectra were recorded from twenty-seven soils sampled from the Logan region in South-East Queensland, Australia. A series of three high quartz soils were mixed with three different kaolinites in varying ratios and NIR spectra collected. Spectra were also collected from six soils as the temperature of the soils was ramped from room temperature up to 6000C. Finally, a forensic scenario was simulated where the transferral of ground soil to shoe soles was investigated. Chemometrics methods such as the commonly known Principal Component Analysis (PCA), the less well known fuzzy clustering (FC) and ranking by means of multicriteria decision making (MCDM) methodology were employed to interpret the spectral results. All soils were characterised using Inductively Coupled Plasma Optical Emission Spectroscopy and X-Ray Diffractometry. Results were promising revealing NIR combined with Chemometrics is capable of discriminating between the various soils. Peak assignments were established by comparing the spectra of known minerals with the spectra collected from the soil samples. The temperature dependent NIR analysis confirmed the assignments of the absorptions due to adsorbed and molecular bound water. The relative intensities of the identified NIR absorptions reflected the quantitative XRD and ICP characterisation results. PCA and FC analysis of the raw soils in the initial NIR investigation revealed that the soils were primarily distinguished on the basis of their relative quartz and kaolinte contents, and to a lesser extent on the horizon from which they originated. Furthermore, PCA could distinguish between the three kaolinites used in the study, suggesting that the NIR spectral region was sensitive enough to contain information describing variation within kaolinite itself. The forensic scenario simulation PCA successfully discriminated between the ‘Backyard Soil’ and ‘Melcann® Sand’, as well as the two sampling methods employed. Further PCA exploration revealed that it was possible to distinguish between the various shoes used in the simulation. In addition, it was possible to establish association between specific sampling sites on the shoe with the corresponding site remaining in the impression. The forensic application revealed some limitations of the process relating to moisture content and homogeneity of the soil. These limitations can both be overcome by simple sampling practices and maintaining the original integrity of the soil. The results from the forensic scenario simulation proved that the concept shows great promise in the forensic discipline.
Resumo:
Hamilton (2001) makes a number of comments on our paper (Harding and Pagan, 2002b). The objectives of this rejoinder are, firstly, to note the areas in which we agree; secondly, to define with greater clarity the areas in which we disagree; and, thirdly, to point to other papers, including a longer version of this response, where we have dealt with some of the issues that he raises. The core of our debate with him is whether one should use an algorithm with a specified set of rules for determining the turning points in economic activity or whether one should use a parametric model that features latent states. Hamilton begins his criticism by stating that there is a philosophical distinction between the two methods for dating cycles and concludes that the method we use “leaves vague and intuitive exactly what this algorithm is intended to measure”. Nothing is further from the truth. When seeking ways to decide on whether a turning point has occurred it is always useful to ask the question, what is a recession? Common usage suggests that it is a decline in the level of economic activity that lasts for some time. For this reason it has become standard to describe a recession as a decline in GDP that lasts for more than two quarters. Finding periods in which quarterly GDP declined for two periods is exactly what our approach does. What is vague about this?