scholarly journals Improving the 14C Dating of Marine Shells from the Canary Islands for Constructing More Reliable and Accurate Chronologies

Radiocarbon ◽  
2012 ◽  
Vol 54 (3-4) ◽  
pp. 943-952 ◽  
Author(s):  
José M Matos Martins ◽  
Alfredo Mederos Martín ◽  
Paulo J Cesário Portela ◽  
António M Monge Soares
Keyword(s):  
Canary Islands ◽  
Radiocarbon Dating ◽  
Coastal Upwelling ◽  
Mean Value ◽  
The Other ◽  
Weighted Mean ◽  
14C Dating ◽  
Marine Mollusk ◽  
Terrestrial Material ◽  
Charred Wood

Radiocarbon dating of closely associated marine mollusk shells and terrestrial material (charred wood or bone) collected from archaeological contexts on Tenerife and Fuerteventura islands allowed us to quantify the marine 14C reservoir effect (ΔR) around the Canary Archipelago. Coastal Fuerteventura has a positive weighted mean ΔR value of +185 ± 30 14C yr, while for Tenerife a range of negative and positive values was obtained, resulting in a ΔR weighted mean value of 0 ± 35 14C yr. These values are in accordance with the hydrodynamic system present off the Canary Islands characterized by a coastal upwelling regime that affects the eastern islands (Fuerteventura and Lanzarote) but not the other islands of the archipelago, namely Tenerife. Because of this oceanographic pattern, we recommend the extrapolation of these results to the remaining islands of the archipelago, i.e. the first value must be used for the eastern islands, while for the central and western islands the acceptable ΔR value is 0 ± 35 14C yr.

Magnesium, calcium, strontium and radiocarbon in the shell of the brachiopod Pajaudina atlantica: implications for growth, biomineralisation and palaeo-proxy application

2020 ◽  
Author(s):  
Volker Liebetrau ◽  
Hana Jurikova ◽  
Marcus Gutjahr ◽  
Daniela Henkel ◽  
Claas Hiebenthal ◽  
...  
Keyword(s):  
Canary Islands ◽  
Electron Microprobe ◽  
Radiocarbon Dating ◽  
Culture Medium ◽  
High Spatial Resolution ◽  
Slow Growth ◽  
The Other ◽  
Resolution Electron ◽  
Shell Production ◽  
Growth Features

<p>Brachiopods present a key taxon for Phanerozoic palaeo-climatic and palaeo-environmental reconstructions, owing to their good preservation and abundance in the geological record. Yet to date, only little is known on the mechanisms that control the incorporation of some key elements into their calcitic shells, as well as the mechanisms behind the biomineral formation itself, especially in thecideid brachiopods. To evaluate the distribution and controls on Mg, Ca, and Sr we examined the composition of natural <em>Pajaudina atlantica</em> Logan, 1988 (Thecideidae, Brachiopoda) originating from Canary Islands, Spain as well as specimens cultured experimentally under various pH-pCO<sub>2</sub> and temperature conditions [1]. At a high-spatial resolution, electron microprobe analyses (EMP) revealed substantial intrashell and intraspecific Mg and Ca heterogeneities that seemed to be principally linked to growth features and different microstructures rather than changes in temperature. Strontium, on the other hand, appeared uniform across the shell and related to the culture medium or seawater Sr content. After almost two years of culturing, however, the new shell production was only minimal and cryptic, and difficult to evaluate by visual inspections. By combining culture-specific geochemical fingerprints with radiocarbon dating of natural samples, we estimated the growth rates to be on the order of several tens to few hundreds of µm per year, which may potentially suggest a large life span and slow growth of this species, and if true, would certainly make them a highly interesting archive for inferring past ocean variabilities. <br><br>[1] Jurikova H., <em>et al.</em> (2019) <em>Geochim. Cosmochim. Acta</em> <strong>248</strong>, 370–386.</p>

scholarly journals The Chronology of Tell El-Daba: A Crucial Meeting Point of 14C Dating, Archaeology, and Egyptology in the 2nd Millennium BC

Radiocarbon ◽  
2012 ◽  
Vol 54 (3-4) ◽  
pp. 407-422 ◽  
Author(s):  
Walter Kutschera ◽  
Manfred Bietak ◽  
Eva Maria Wild ◽  
Christopher Bronk Ramsey ◽  
Michael Dee ◽  
...  
Keyword(s):  
Plant Material ◽  
Radiocarbon Dating ◽  
Nile Delta ◽  
Eastern Mediterranean ◽  
The Other ◽  
14C Dating ◽  
Archaeological Evidence ◽  
The Difference ◽  
The One ◽  
Different Cultures

Radiocarbon dating at the Tell el-Daba site in the Nile Delta has created an enigma for many years. Despite great efforts, the difference of about 120 yr between the chronology based on 14C dates and the one based on archaeological evidence linked to the Egyptian historical chronology has not been solved. In order to foster open discussions on this discrepancy, we present here the results of 40 14C accelerator mass spectrometry (AMS) measurements on short-lived plant material assigned to 14 different phases of the Tell el-Daba excavation, spanning 600 yr (about 2000–1400 BC). On the one hand, the recently established agreement between 14C dates and dynastic Egypt (Bronk Ramsey et al. 2010) makes it unlikely that the problem lies in the 14C dates and/or the Egyptian historical chronology. On the other hand, the extensive archaeological evidence from Tell el-Daba linked to many different cultures in the eastern Mediterranean and to the Egyptian historical chronology provides strong evidence for an absolute chronology shifted by about 120 yr with respect to the 14C dates.

scholarly journals Marine Radiocarbon Reservoir Effect of Coastal Waters Off Cape Verde Archipelago

Radiocarbon ◽  
2011 ◽  
Vol 53 (2) ◽  
pp. 289-296 ◽  
Author(s):  
António M Monge Soares ◽  
José M Matos Martins ◽  
João Luís Cardoso
Keyword(s):  
Coastal Waters ◽  
Coastal Upwelling ◽  
Mean Value ◽  
Cape Verde ◽  
Weighted Mean ◽  
Reservoir Effect ◽  
Mollusk Shells ◽  
Marine Samples ◽  
Oceanographic Conditions ◽  
Marine Shell

Quantification of the marine radiocarbon reservoir effect (ΔR) is essential in order to calibrate conventional 14C dates from marine shell samples with reliability. ΔR also provides information concerning the intensity of coastal upwelling in marine regions influenced by this phenomenon. 14C ages of closely associated marine samples (mollusk shells) and terrestrial samples (goat bones) from São Vicente Island, Cape Verde Archipelago, permitted the first calculation of the marine 14C reservoir effect in this region. A ΔR weighted mean value of 70 ± 70 14C yr was obtained. This value is in accordance with the previously published oceanographic conditions of the region indicating the existence of a seasonal active upwelling regime.

scholarly journals Reservoir Effect of Coastal Waters Off Western and Northwestern Galicia

Radiocarbon ◽  
2007 ◽  
Vol 49 (2) ◽  
pp. 925-936 ◽  
Author(s):  
António M Monge Soares ◽  
João M Alveirinho Dias
Keyword(s):  
Surface Water ◽  
Environmental Factors ◽  
Iron Age ◽  
Coastal Waters ◽  
High Variability ◽  
Medieval Period ◽  
Marine Mollusk ◽  
Positive Peak ◽  
Terrestrial Material ◽  
Charred Wood

Differences in the radiocarbon ages of closely associated marine mollusk shells and terrestrial material (charred wood or bones) from several Galician archaeological contexts are significant from the Iron Age to Medieval times. δR values show high variability, ranging from −280 ± 70 to 270 ± 40 14C yr. The set of δR values also presents a strong positive peak (δR = 270 ± 40 14C yr) at 860 ± 90 BP, which matches another peak found for western Portuguese coastal waters. The data obtained, namely the negative or close to zero δR values, suggest that the reduced offset between atmospheric and surface water 14C content is due to the existence of a strong stratification of the water column and environmental factors in the Galician rías during the Iron Age and the Medieval period.

scholarly journals Chronological Development of the Tripolye Culture Giant-Settlement of Talianki (Ukraine): 14C Dating vs. Pottery Typology

Radiocarbon ◽  
2011 ◽  
Vol 53 (4) ◽  
pp. 645-657 ◽  
Author(s):  
Yuri Rassamakin ◽  
Francesco Menotti
Keyword(s):  
Radiocarbon Dating ◽  
The Other ◽  
14C Dating ◽  
Relative Chronology ◽  
Phases Of Development ◽  
One Step ◽  
Tripolye Culture ◽  
Better Than

The long tradition of relative chronology based on pottery typology has often hindered the development of radiocarbon dating amongst the Tripolye giant-settlement in Ukraine. Although it is fairly reliable, relative chronology encounters insurmountable obstacles in identifying internal phases of development within a single settlement. This paper presents the first attempt to use 14C dates to monitor the chronological development of the Talianki giant-settlement, from its formation to the various phases of development and the final decline. It then goes one step further by proving genetic links between 2 “neighboring” settlements, confirming that one is the result of migration processes of the other. This study does not intend to prove that one of the dating techniques is better than the other, but to demonstrate that a synergetic combination of the 2 methods will certainly lead to more reliable results.

scholarly journals Coastal Upwelling and Radiocarbon—Evidence for Temporal Fluctuations in Ocean Reservoir Effect off Portugal During the Holocene

Radiocarbon ◽  
2006 ◽  
Vol 48 (1) ◽  
pp. 45-60 ◽  
Author(s):  
António M Monge Soares ◽  
João M Alveirinho Dias
Keyword(s):  
Coastal Upwelling ◽  
Climatic Factors ◽  
Marine Mollusk ◽  
Reservoir Effect ◽  
Temporal Fluctuations ◽  
The Holocene ◽  
Mollusk Shells ◽  
Portuguese Coast ◽  
Strong Intensity ◽  
Terrestrial Material

This paper focuses on the use of the radiocarbon content of marine shells collected along the Portuguese coast as a proxy for the intensity of coastal upwelling off of Portugal. Differences in the 14C ages of closely associated marine mollusk shells and terrestrial material (charcoal or bones) from several Portuguese archaeological contexts seem to be significant throughout the Holocene. ΔR values range from 940 ± 50 to −160 ± 40 14C yr. Five of these values are significantly higher than the modern value (250 ± 25 14C yr), while the remaining values are lower. The modern value was calculated by measuring the 14C content of live-collected, pre-bomb marine mollusk shells. This value is in accordance with an active upwelling of strong intensity that currently occurs off of Portugal. Some primary observations based on data presented here can be made: i) during the Holocene important changes have occurred in the ocean reservoir effect off the Portuguese coast; ii) these fluctuations may be correlated with regional oceanographic changes, namely with changes in the strength of coastal upwelling; and iii) these changes suggest some sort of variability of the climatic factors forcing coastal upwelling off of Portugal.

scholarly journals BATCH PROCESSING OF TREE-RING SAMPLES FOR RADIOCARBON ANALYSIS

Radiocarbon ◽  
2020 ◽  
pp. 1-13
Author(s):  
Alexandra Fogtmann-Schulz ◽  
Sabrina G K Kudsk ◽  
Florian Adolphi ◽  
Christoffer Karoff ◽  
Mads F Knudsen ◽  
...  
Keyword(s):  
High Precision ◽  
Tree Rings ◽  
Precision Measurement ◽  
Radiocarbon Dating ◽  
The Other ◽  
High Precision Measurement ◽  
Machine Performance ◽  
High Throughput Method ◽  
Ca 50 ◽  
Low Activity

ABSTRACT We here present a comparison of methods for the pretreatment of a batch of tree rings for high-precision measurement of radiocarbon at the Aarhus AMS Centre (AARAMS), Aarhus University, Denmark. The aim was to develop an efficient and high-throughput method able to pretreat ca. 50 samples at a time. We tested two methods for extracting α-cellulose from wood to find the most optimal for our use. One method used acetic acid, the other used HCl acid for the delignification. The testing was conducted on background 14C samples, in order to assess the effect of the different pretreatment methods on low-activity samples. Furthermore, the extracted wood and cellulose fractions were analyzed using Fourier transform infrared (FTIR) spectroscopy, which showed a successful extraction of α-cellulose from the samples. Cellulose samples were pretreated at AARAMS, and the graphitization and radiocarbon analysis of these samples were done at both AARAMS and the radiocarbon dating laboratory at Lund University to compare the graphitization and AMS machine performance. No significant offset was found between the two sets of measurements. Based on these tests, the pretreatment of tree rings for high-precision radiocarbon analysis at AARAMS will henceforth use HCI for the delignification.

scholarly journals Investigation of a cold-based ice apron on a high-mountain permafrost rock wall using ice texture analysis and micro-14C dating: a case study of the Triangle du Tacul ice apron (Mont Blanc massif, France)

2021 ◽  
pp. 1-8
Author(s):  
Grégoire Guillet ◽  
Susanne Preunkert ◽  
Ludovic Ravanel ◽  
Maurine Montagnat ◽  
Ronny Friedrich
Keyword(s):  
Radiocarbon Dating ◽  
Boundary Migration ◽  
Ice Core ◽  
Ice Cores ◽  
Shear Plane ◽  
High Mountain ◽  
14C Dating ◽  
Rock Wall ◽  
Major Mechanism ◽  
Mont Blanc Massif

Abstract The current paper studies the dynamics and age of the Triangle du Tacul (TDT) ice apron, a massive ice volume lying on a steep high-mountain rock wall in the French side of the Mont-Blanc massif at an altitude close to 3640 m a.s.l. Three 60 cm long ice cores were drilled to bedrock (i.e. the rock wall) in 2018 and 2019 at the TDT ice apron. Texture (microstructure and lattice-preferred orientation, LPO) analyses were performed on one core. The two remaining cores were used for radiocarbon dating of the particulate organic carbon fraction (three samples in total). Microstructure and LPO do not substantially vary with along the axis of the ice core. Throughout the core, irregularly shaped grains, associated with strain-induced grain boundary migration and strong single maximum LPO, were observed. Measurements indicate that at the TDT ice deforms under a low strain-rate simple shear regime, with a shear plane parallel to the surface slope of the ice apron. Dynamic recrystallization stands out as the major mechanism for grain growth. Micro-radiocarbon dating indicates that the TDT ice becomes older with depth perpendicular to the ice surface. We observed ice ages older than 600 year BP and at the base of the lowest 30 cm older than 3000 years.

scholarly journals The laboratory findings and different COVID-19 severities: a systematic review and meta-analysis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Erfan Kazemi ◽  
Reihane Soldoozi Nejat ◽  
Fatemeh Ashkan ◽  
Hossein Sheibani
Keyword(s):  
Systematic Review ◽  
Platelet Count ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Lymphocyte Count ◽  
Leukocyte Count ◽  
Mean Value ◽  
The Other ◽  
Invasive Ventilation ◽  
Laboratory Findings

Abstract Background Abnormal laboratory findings are common in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The aim of this systematic review was to investigate the effect of the level of some laboratory factors (C-reactive protein (CRP), creatinine, leukocyte count, hemoglobin, and platelet count) on the severity and outcome of coronavirus disease 2019 (COVID-19). Methods We searched PubMed, Web of Science, Scopus, and Google Scholar. We collected the articles published before May 26, 2020. We gathered the laboratory factors in groups of patients with COVID-19, and studied the relation between level of these factors with severity and outcome of the disease. Results Mean CRP level, creatinine, hemoglobin, and the leukocytes count in the critically ill patients were significantly higher than those of the other groups (non-critical patients); mean CRP = 54.81 mg/l, mean creatinine = 86.82 μmol/l, mean hemoglobin = 144.05 g/l, and mean leukocyte count = 7.41 × 109. The lymphocyte count was higher in patients with mild/moderate disease (mean: 1.32 × 109) and in the invasive ventilation group (mean value of 0.72 × 109), but it was considerably lower than those of the other two groups. The results showed that the platelet count was higher in critically ill patients (mean value of 205.96 × 109). However, the amount was lower in the invasive ventilation group compared with the other groups (mean level = 185.67 × 109). Conclusion With increasing disease severity, the leukocyte count and the level of CRP increase significantly and the lymphocyte count decreases. There seems to be a significant relation between platelet level, hemoglobin, and creatinine level with severity of the disease. However, more studies are required to confirm this.

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