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Artículos de revistas sobre el tema "Chemical dating"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 5 de febrero de 2022

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1

Perroud, Hervé, Annick Chauvin y Michel Rebelle. "Hydrocarbon seepage dating through chemical remagnetization". Geological Society, London, Special Publications 98, n.º 1 (1995): 33–41. http://dx.doi.org/10.1144/gsl.sp.1995.098.01.03.

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2

Spear, Frank S., Joseph M. Pyle y Daniele Cherniak. "Limitations of chemical dating of monazite". Chemical Geology 266, n.º 3-4 (agosto de 2009): 218–30. http://dx.doi.org/10.1016/j.chemgeo.2009.06.007.

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3

Glover, M. J. y G. F. Phillips. "Chemical methods for the dating of fossils". Journal of Applied Chemistry 15, n.º 12 (4 de mayo de 2007): 570–76. http://dx.doi.org/10.1002/jctb.5010151204.

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4

Bywater, Robert P. "On dating stages in prebiotic chemical evolution". Naturwissenschaften 99, n.º 3 (15 de febrero de 2012): 167–76. http://dx.doi.org/10.1007/s00114-012-0892-6.

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5

Kusiak, Monika Agnieszka y Janusz Lekki. "Proton microprobe for chemical dating of monazite". Gondwana Research 14, n.º 4 (diciembre de 2008): 617–23. http://dx.doi.org/10.1016/j.gr.2008.01.011.

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6

Engi, Martin, Andrij K. Cheburkin y Viktor Köppel. "Nondestructive chemical dating of young monazite using XRF". Chemical Geology 191, n.º 1-3 (noviembre de 2002): 225–41. http://dx.doi.org/10.1016/s0009-2541(02)00158-4.

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7

Scherrer, Nadim C., Martin Engi, Alfons Berger, Randall R. Parrish y Andriy Cheburkin. "Nondestructive chemical dating of young monazite using XRF". Chemical Geology 191, n.º 1-3 (noviembre de 2002): 243–55. http://dx.doi.org/10.1016/s0009-2541(02)00159-6.

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8

Cui, Ji-Qiang, Shui-Yuan Yang, Shao-Yong Jiang y Jing Xie. "Multipoint Background Analysis for Chemical Dating of Monazite". Microscopy and Microanalysis 25, S2 (agosto de 2019): 2364–65. http://dx.doi.org/10.1017/s1431927619012558.

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9

Dunbar, E., G. T. Cook, P. Naysmith, B. G. Tripney y S. Xu. "AMS 14C Dating at the Scottish Universities Environmental Research Centre (SUERC) Radiocarbon Dating Laboratory". Radiocarbon 58, n.º 1 (11 de enero de 2016): 9–23. http://dx.doi.org/10.1017/rdc.2015.2.

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AbstractThis paper describes all the major procedures adopted by the Scottish Universities Environmental Research Centre (SUERC) Radiocarbon Dating Laboratory. This includes sample pretreatment, graphite production, accelerator mass spectrometry (AMS) measurement, associated stable isotope measurements, data handling, and age calculations, but with the main emphasis being on the chemical pretreatment methods. All of the above enable the laboratory to provide a complete analytical service comprising advice on sample selection, preparation and analysis of samples, and Bayesian analysis of resulting 14C (and other) data. This applies to both our research and commercial activities. The pretreatment methods that we mainly focus on are used to remove contaminant carbon from a range of sample types or to isolate a particular chemical fraction from a sample prior to combustion/hydrolysis, graphitization, and subsequent AMS 14C measurement. The methods described are for bone (collagen extraction, with and without ultrafiltration), cremated bone, tooth enamel, charcoal, grain, carbon residues, shell, wood (including alpha-cellulose isolation), peat, sediments, textiles, fuel/biofuel, and forensic samples.

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10

Churcher, Ian. "Speed dating for reactions". Nature Chemistry 5, n.º 7 (20 de junio de 2013): 554–55. http://dx.doi.org/10.1038/nchem.1689.

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11

Gillespie, Richard. "Dating the First Australians". Radiocarbon 44, n.º 2 (2002): 455–72. http://dx.doi.org/10.1017/s0033822200031830.

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The dating of selected archaeological and megafaunal sites from the Australian region is reviewed, with emphasis on recent work at some of the oldest sites. Improved chemical procedures with decreased analytical background for 14C analysis, combined with new luminescence dating methods, has confirmed many of the results processed decades ago and significantly increased the maximum age for some others. The oldest occupation horizons in four different regions reliably dated by defendable multi-method results are in the range 42–48,000 calendar years ago, overlapping with the age range for similarly well-dated undisturbed sites containing the youngest extinct megafauna. There is less secure evidence suggesting some archaeology may be earlier and some megafauna may have survived later than this period.

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12

Fanti, Giulio, Pierandrea Malfi y Fabio Crosilla. "Mechanical ond opto-chemical dating of the Turin Shroud". MATEC Web of Conferences 36 (2015): 01001. http://dx.doi.org/10.1051/matecconf/20153601001.

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13

REESE, K. M. "Kennewick Man subjected to radiocarbon dating". Chemical & Engineering News 77, n.º 39 (27 de septiembre de 1999): 64. http://dx.doi.org/10.1021/cen-v077n039.p064.

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14

Zaitseva, G. I. "Chemical Composition and Sample Preparation of Archaeological Wood for Radiocarbon Dating". Radiocarbon 37, n.º 2 (1995): 311–17. http://dx.doi.org/10.1017/s0033822200030782.

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The chemical composition of wood from archaeological sites differs from that of modern wood. The chemical changes depend on the microenvironment of the surrounding matrix more than the time of preservation. Chemical treatment of decomposed wood results in a great loss of initial material. The degree of wood decomposition should be taken into account in the preparation of samples for 14C dating. The main fraction of archaeological decomposed wood is a degraded lignin, with most cellulose totally decomposed. Nevertheless, decomposed wood can be a reliable material for 14C dating archaeological sites. Loss of material through sample preparation can be reduced by using fairly weak concentrations of chemical reagents without influencing the reliability of the dates.

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15

Schmitz, Sylvia, Andreas Möller, Max Wilke, Wolfgang Malzer, Birgit Kanngiesser, Romain Bousquet, Alfons Berger y Senecio Schefer. "Chemical U-Th-Pb dating of monazite by 3D-Micro X-ray fluorescence analysis with synchrotron radiation". European Journal of Mineralogy 21, n.º 5 (30 de octubre de 2009): 927–45. http://dx.doi.org/10.1127/0935-1221/2009/0021-1964.

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16

Takehara, Lucy, Farid Chemale Júnior, Léo A. Hartmann, Ivo A. Dussin y Koji Kawashita. "U-Pb dating by zircon dissolution method using chemical abrasion". Anais da Academia Brasileira de Ciências 84, n.º 2 (junio de 2012): 399–405. http://dx.doi.org/10.1590/s0001-37652012000200011.

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Chemical abrasion was carried out on zircons grains of the Temora II standard for U-Pb dating prior to analyses using in situ Laser Ablation-MultiCollector Ion Coupled Plasma Mass Spectrometer (LA-ICPMS) followed by the Isotope Dissolution Thermal Ionization Mass Spectrometer (ID-TIMS) method. The proposed methodology was herein applied in order to reduce primarily the effects of secondary Pb loss, the presence of common lead and/or silicate impurities. Nine Temora II zircon grains were analyzed by the laser ablation method yielding an age of 418.3±4.3 Ma. Zircon grains of a same population were separated for chemical abrasion before dissolution and mass spectrometry analyses. Six fractions of them were separated for isotope dissolution using 235U-205Pb mixed spike after we have checked and assured the laboratory conditions of low blank values for total Pb of less than 2 pg/g. The obtained U-Pb zircon age by the ID-TIMS method was 415.7±1.8 Ma (error 0.43 %) based on four successful determinations. The results are consistent with the published ages for the Temora diorite (Temora I â€“ 416.75±1.3 Ma; Temora II â€“ 416.78±0.33 Ma) and established as 416±0.33 Ma. The technique is thus recommended for high precision U-Pb zircon analyses (error < 1 %), mainly for high resolution stratigraphic studies of Phanerozoic sequences.

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17

Dee, M. W., S. W. L. Palstra, A. Th Aerts-Bijma, M. O. Bleeker, S. de Bruijn, F. Ghebru, H. G. Jansen et al. "Radiocarbon Dating at Groningen: New and Updated Chemical Pretreatment Procedures". Radiocarbon 62, n.º 1 (9 de septiembre de 2019): 63–74. http://dx.doi.org/10.1017/rdc.2019.101.

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ABSTRACTThe Centre for Isotope Research (CIO) at the University of Groningen has operated a radiocarbon (14C) dating laboratory for almost 70 years. In 2017, the CIO received a major upgrade, which involved the relocation of the laboratory to new purpose-built premises, and the installation of a MICADAS accelerator mass spectrometer. This period of transition provides an opportunity to update the laboratory’s routine procedures. This article addresses all of the processes and quality checks the CIO has in place for registering, tracking and pretreating samples for radiocarbon dating. Complementary updates relating to radioisotope measurement and uncertainty propagation will be provided in other forthcoming publications. Here, the intention is to relay all the practical information regarding the chemical preparation of samples, and to provide a concise explanation as to why each step is deemed necessary.

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18

Udisti, R. "Multiparametric Approach for Chemical Dating of Snow Layers from Antarctica". International Journal of Environmental Analytical Chemistry 63, n.º 3 (julio de 1996): 225–44. http://dx.doi.org/10.1080/03067319608026268.

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19

Cross, A., S. Jaireth, R. Rapp y R. Armstrong. "Reconnaissance-style EPMA chemical U–Th–Pb dating of uraninite". Australian Journal of Earth Sciences 58, n.º 6 (agosto de 2011): 675–83. http://dx.doi.org/10.1080/08120099.2011.598190.

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20

Kulkova, Marianna Alexeevna. "RADIOCARBON DATING OF ANCIENT POTTERY". Samara Journal of Science 3, n.º 3 (18 de julio de 2014): 115–22. http://dx.doi.org/10.17816/snv20143212.

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The radiocarbon dating of ancient ceramics is an important aspect of investigations both the radiocarbon analysis and the archaeology. The time of a making and using of pottery corresponds directly with the time of the ancient people existing. In spite on that fact that the pottery radiocarbon dating has many problems because of different sources of carbon inside pottery, there is the possibility for correct radiocarbon dating with using both the AMS technique and the conventional technique. The main problem of pottery radiocarbon dating is how to separate intrinsic pottery carbon from older geological carbon and younger carbon absorbed by pottery pores during burial. The examination of basic stages of pottery making and using gives the possibility to assess the main sources of carbon entrance to a ceramic vessel. The compositional analysis of clay and temper that had been used for pottery making should be considered. The method of the temperature control during combustion should be applied in process of the radiocarbon dating. It is very important to supply the careful chemical pretreatment of ceramics with aim to remove the older and younger contaminations. The comparison of pottery dates obtained with the relative dating according to pottery typology should use for control. The other problem of the radiocarbon dating of pottery is the reservoir effect if the freshwater and the seawater fish or seafood were used in a cooking process. If the clay has the high carbonate concentration or shells inside pot-sherds the determination of d 13C should be done after carbonate removing. The careful chemical pretreatment of ceramics must guarantee the removing of humic acids forming after burial of pot-sherds and as well as in result of food cooking. The examination of d 13C should be provided for organics from pot-sherds. The correction of radiocarbon age can be realized. If it is possible the total content of carbon should determine in pot-sherds as well. In article the

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21

Titarenko, A., A. Recio-Blanco, P. de Laverny, M. Hayden, G. Guiglion y C. Worley. "[Y/Mg] stellar dating calibration". Proceedings of the International Astronomical Union 12, S330 (abril de 2017): 267–68. http://dx.doi.org/10.1017/s1743921317006780.

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AbstractGaia DR1 has opened a new era of stellar age dating, that is crucial for many astrophysical objectives. In addition, the Gaia based isochrone fitting ages can be compared to other chemical clocks like the [Y/Mg] one (Nissen et al. 2015). In our work we have used ESO archived data of the AMBRE project (de Laverny et al. 2013) for UVES spectra, in order to evaluate the age [Y/Mg] abundance correlation for turn off stars. 310 turn off stars of the UVES-archive (setups 564 and 580) are included in the TGAS database. Isochrone fitting ages were derived. We have applied the GAUGUIN procedure for those stars to derive the Mg and the Y abundances. As the result we present the [Y/Mg] vs stellar age dependence for ~40 TO-stars.

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22

GILMAN, VICTORIA. "Quartz Hydration Fills Gap In Dating Artifacts". Chemical & Engineering News 82, n.º 16 (19 de abril de 2004): 10. http://dx.doi.org/10.1021/cen-v082n016.p010a.

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23

Yuan, Sixun, Xiaohong Wu, Kexin Liu, Zhiyu Guo, Xiaolin Cheng, Yan Pan y Jinxia Wang. "Removal of Contaminants from Oracle Bones During Sample Pretreatment". Radiocarbon 49, n.º 2 (2007): 211–16. http://dx.doi.org/10.1017/s0033822200042132.

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Animal bones and tortoise shells were used for divination by the Chinese royal family during the Shang Dynasty (∼16th–11th century BC), and the divination results were recorded as inscriptions on oracle bones and shells, which are very valuable cultural remains and record many important events in the Shang Dynasty period. Thus, radiocarbon dating of oracle bones was used to build a precise chronology of the late Shang Dynasty. Due to their original burial conditions and the fact that in subsequent decades the pieces were traded or archived in museums, oracle bones are expected to be contaminated with exogenous materials from the environment and the conservation process. During dating, we found that some samples were contaminated by conservation chemical reagents. The contaminated samples were purified by removing exogenous chemicals with a series of organic solvents, in a method modified from Bruhn et al. (2001). Both whole bone and gelatin samples were processed with this purification method, resulting in satisfactory improvements in dating results.

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24

Prima, Cinthya Fatama, I. Nyoman Suarsana y Ni Made Wiasti. "Tinder Sebagai Platform Pencarian Jodoh di Zaman Digital". Humanis 25, n.º 3 (28 de agosto de 2021): 379. http://dx.doi.org/10.24843/jh.2021.v25.i03.p15.

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The phenomenon of dating applications is increasingly growing in society. This is evidenced by the rise of dating applications. Tinder is one of the most talked about dating apps. Tinder brings people a change in the way it is social. Since Tinder was launched, now humans can easily make new friends virtually. Dating applications are believed to be able to provide a solution when a match comes for its users. This is what attracts researchers to dig deeper into the phenomenon of matchmaking through the Tinder application as a matchmaking platform in the digital era. The theory used by the researcher is social action theory and theory of love by Wheel theory. This research also uses a qualitative descriptive method and a qualitative approach. The results show that the resource person uses the Tinder application to find new friends, girlfriends and even husbands / wives. The researcher concluded that the actions taken by the informants on average had the same answer. This action is done for the purpose of finding a new socials circle.

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25

Colman, Steven M., Kenneth L. Pierce y Peter W. Birkeland. "Suggested Terminology for Quaternary Dating Methods". Quaternary Research 28, n.º 2 (septiembre de 1987): 314–19. http://dx.doi.org/10.1016/0033-5894(87)90070-6.

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AbstractClassification of Quaternary dating methods should be based on the level of quantitative information and the degree of confidence contained in the age estimates produced by the dating methods. We recommend the use of the terms numerical-age, calibrated-age, relative-age, and correlated-age to describe these levels. We also classify dating methods by type into sideral, isotopic, radiogenic, chemical and biological, geomorphic, and correlation methods. The use of “absolute” is inappropriate for most dating methods, and should be replaced by “numerical.” The use of “date” should be minimized in favor of “age” or “age estimate.” We recommend use of the abbreviations ka and Ma for most ages; calender dates can be used where appropriate and yr B.P. can be used for radiocarbon ages.

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26

Beer, Juerg y Michael Sturm. "Dating of Lake and Loess Sediments". Radiocarbon 37, n.º 1 (1995): 81–86. http://dx.doi.org/10.1017/s003382220001482x.

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Lake and loess sediments represent archives that record important information about the iocal, regional and global climate conditions in the past. Lake sediments consist of autochthonous particles formed by biogeochemical processes within the lake and allochthonous particles brought into the lake from the catchment area. After deposition, the stratigraphy of the sediment can be altered by chemical, physical and biological processes. Under favored conditions, the sediment shows individual annual layers (varves), which can be used to date the sediment. Other dating methods are based on radioactive decay (14C, 210Pb) or on time markers such as tephra layers, deposits of natural catastrophes, e.g., floods, or radioactivity, e.g., emissions from a nuclear power plant.

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27

Bruhn, Frank, Andreas Möller, Soey H. Sie y Bas J. Hensen. "U–Th–Pb chemical dating of monazites using the proton microprobe". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 158, n.º 1-4 (septiembre de 1999): 616–20. http://dx.doi.org/10.1016/s0168-583x(99)00385-7.

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28

Dee, M. W., S. W. L. Palstra, A. Th Aerts-Bijma, M. O. Bleeker, S. de Bruijn, F. Ghebru, H. G. Jansen et al. "Radiocarbon Dating at Groningen: New and Updated Chemical Pretreatment Procedures – CORRIGENDUM". Radiocarbon 62, n.º 1 (19 de noviembre de 2019): 261. http://dx.doi.org/10.1017/rdc.2019.140.

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29

Long, Leon E. "Absolute Age Determination: Physical and Chemical Dating Methods and Their Application". Geochimica et Cosmochimica Acta 55, n.º 6 (junio de 1991): 1751. http://dx.doi.org/10.1016/0016-7037(91)90149-y.

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30

Bierman, Paul R. y Alan R. Gillespie. "Accuracy of rock-varnish chemical analyses: Implications for cation-ratio dating". Geology 19, n.º 3 (1991): 196. http://dx.doi.org/10.1130/0091-7613(1991)019<0196:aorvca>2.3.co;2.

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31

Moorbath, Stephen. "Absolute age determination: Physical and chemical dating methods and their application". Physics of the Earth and Planetary Interiors 71, n.º 1-2 (abril de 1992): 132. http://dx.doi.org/10.1016/0031-9201(92)90040-3.

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32

Cayci, G., A. Baran, H. Ozaytekin, C. Kutuk, S. Karaca y N. Cicek. "Morphology, chemical properties, and radiocarbon dating of eutrophic peat in Turkey". CATENA 85, n.º 3 (junio de 2011): 215–20. http://dx.doi.org/10.1016/j.catena.2011.01.005.

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33

Odin, G. S. "Absolute age determination. Physical and chemical dating methods and their application". Precambrian Research 54, n.º 2-4 (enero de 1992): 323. http://dx.doi.org/10.1016/0301-9268(92)90077-2.

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34

Johnsson, Kjell. "Chemical Dating of Bones Based on Diagenetic Changes in Bone Apatite". Journal of Archaeological Science 24, n.º 5 (mayo de 1997): 431–37. http://dx.doi.org/10.1006/jasc.1996.0127.

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35

Hodgins, G. W. L., T. D. Butters, C. Bronk Ramsey y R. E. M. Hedges. "The Chemical and Enzymatic Hydrolysis of Archaeological Wood Cellulose and Monosaccharide Purification by High Ph Anion Exchange Chromatography for Compound-Specific Radiocarbon Dating". Radiocarbon 43, n.º 2A (2001): 209–15. http://dx.doi.org/10.1017/s0033822200038029.

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Preliminary experiments were carried out on archaeological wood to investigate methods of cellulose hydrolysis and carbohydrate monomer purification for the purpose of compound-specific radiocarbon dating. The Chelford log, a known 14C dead source of wood cellulose, was selected for study in order to investigate the levels of contamination introduced during sample purification. Two methods of hydrolysis were examined, mineral acid hydrolysis and enzyme hydrolysis using cellulase from Penicillium funiculosum. Under the conditions described, enzymolysis was far superior to acid hydrolysis in terms of the glucose monomer yield. Glucose monomer purification was accomplished using high pH anion exchange chromatography with pulsed amperometric detection. This high performance liquid chromatography (HPLC) method does not require sample derivatization and the chromatography products can be collected in water. These characteristics make it potentially well suited to carbon dating applications. 14C dating of chromatographically purified glucose fractions revealed significant levels of contamination had accumulated during both protocols. Glucose contamination from the cellulase enzyme preparation was a major source of contamination within the enzymatically hydrolyzed samples. Ultrafiltration of the enzyme removed some but not all of this contamination. The contamination must be reduced 10-fold before the methodology could be viable for dating. This hydrolysis/HPLC method is also being investigated for 14C dating of other carbohydrate polymers such as chitin.

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36

ZURER, PAMELA. "Rumors fly about dating of Shroud of Turin". Chemical & Engineering News 66, n.º 36 (5 de septiembre de 1988): 5. http://dx.doi.org/10.1021/cen-v066n036.p005a.

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37

GOODRUM, MATTHEW R. y CORA OLSON. "The quest for an absolute chronology in human prehistory: anthropologists, chemists and the fluorine dating method in palaeoanthropology". British Journal for the History of Science 42, n.º 1 (13 de enero de 2009): 95–114. http://dx.doi.org/10.1017/s000708740800157x.

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AbstractBy the early twentieth century there was a growing need within palaeoanthropology and prehistoric archaeology to find a way of dating fossils and artefacts in order to know the age of specific specimens, but more importantly to establish an absolute chronology for human prehistory. The radiocarbon and potassium–argon dating methods revolutionized palaeoanthropology during the last half of the twentieth century. However, prior to the invention of these methods there were attempts to devise chemical means of dating fossil bone. Collaborations between Emile Rivière and Adolphe Carnot in the 1890s led to the development of the fluorine dating method, but it was not until the 1940s that this method was improved and widely implemented by Kenneth Oakley to resolve a number of problems in palaeoanthropology, including the Piltdown Man controversy. The invention of the fluorine dating method marked a significant advance in the quest for absolute dating in palaeoanthropology, but it also highlights interesting problems and issues relating to the ability of palaeoanthropologists and chemists to bring together different skills and bodies of knowledge in order successfully to develop and apply the fluorine dating method.

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38

Piotrowska, Natalia, Andrzej Bluszcz, Dieter Demske, Wojciech Granoszewski y Georg Heumann. "Extraction and AMS Radiocarbon Dating of Pollen from Lake Baikal Sediments". Radiocarbon 46, n.º 1 (2004): 181–87. http://dx.doi.org/10.1017/s0033822200039503.

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This work focuses on the preparation and dating of sporomorph (pollen and spores) concentrates of high purity. Three sediment cores recovered from Lake Baikal within the EU-Project CONTINENT were subjected to palynological analyses and accelerator mass spectrometry (AMS) radiocarbon dating. Laboratory processing of concentrates was aimed at the removal of non-sporomorph organic matter by means of chemical treatment, micro-sieving, and heavy liquid separation. The obtained concentrates were checked under the microscope and sample purity was estimated on the basis of particle counts. The results of AMS 14C dating show differences in the sedimentation rate among 3 sites of Lake Baikal.

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39

Chenciner, Robert. "Ancient Copper Alloy Figurines from Daghestan". Antiquaries Journal 79 (septiembre de 1999): 59–79. http://dx.doi.org/10.1017/s0003581500044486.

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Nothing appears to have been written in English about a group of powerfully-sculpted lost-wax copper alloy, standing, naked figurines, 30–60mm tall, mainly from mountainous regions of west Daghestan and south-east Chechnya in the Caucasus. More than a hundred of these phallic (male), or otherwise sexually explicit (female and hermaphrodite) figurines have been found at different places at different dates since 1867 up to the present day. Most writers have suggested datings from the first millennium BC and indeed dating between 500 BC and AD 500 has been recently confirmed by the first technical and chemical analysis of a sample of these figurines by Dr Peter Northover. The thirteen figurines which he analysed are catalogued here. However, a Daghestani archaeologist Dr M S Gadjiev has recently proposed that the period of their manufacture is from the sixth to ninth centuries AD, since similar figurines have been found with a small spoon, datable to that period. The author's suggested interpretations of the ‘adoration’ and ‘cup-bearer’ types of figurine, which occur most frequently, do not affect the debate on their dating.

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40

Titarenko, A., A. Recio-Blanco, P. de Laverny, M. Hayden y G. Guiglion. "The AMBRE Project: [Y/Mg] stellar dating calibration with Gaia". Astronomy & Astrophysics 622 (29 de enero de 2019): A59. http://dx.doi.org/10.1051/0004-6361/201833721.

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Chemical abundance dating methods open new paths for temporal evolution studies of the Milky Way stellar populations. In this paper, we use a high spectral resolution database of turn-off stars in the solar neighbourhood to study the age dependence of the [Y/Mg] chemical abundance ratio. Our analysis reveals a clear correlation between [Y/Mg] and age for thin disc stars of different metallicities, in synergy with previous studies of solar-type stars. In addition, no metallicity dependence with stellar age is detected, allowing us to use the [Y/Mg] ratio as a reliable age proxy. Finally, the [Y/Mg]–age relation presents a discontinuity between thin and thick disc stars around 9–10 Gyr. For thick disc stars, the correlation has a different zero point and probably a steeper trend with age, reflecting the different chemical evolution histories of the two disc components.

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41

Gay, M., M. De Angelis y J. L. Lacoume. "Exploitation of chemical profiles by conjugate variable analysis: application to the dating of a tropical ice core (Nevado Illimani, Bolivia)". Climate of the Past Discussions 9, n.º 3 (24 de junio de 2013): 3399–447. http://dx.doi.org/10.5194/cpd-9-3399-2013.

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Abstract. Ice core dating is a key parameter for the interpretation of the ice archives. However, the relationship between ice depth and age can generally not be easily established and requires to combine a large number of investigations and/or modeling effort. This paper presents a new approach of ice core dating based on conjugate variable (depth and spatial frequency) analysis of chemical profiles. The relationship between the depth of a given ice layer and the date it was deposited is determined using ion concentration depth profiles obtained along a one hundred-meters deep ice core recovered in the summit area of the Nevado Illimani (6350 m a.s.l.), located in the Eastern Bolivian Andes (16°37' S, 67°46' W). The results of Fourier conjugate analysis and wavelet tranforms are first compared. Both methods are applied to nitrate concentration depth profile. The resulting chronologies are checked by comparison with the multi-proxy year-by-year dating published by de Angelis et al. (2003) and with volcanic tie points, demonstrating the efficiency of Fourier conjugate analysis when tracking the natural variability of chemical proxies. The Fourier conjugate analysis is then applied to concentration depth profiles of seven other ions thus providing information on the suitability of each of them for dating studies of tropical Andean ice cores.

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42

Elisha, Bar, Perach Nuriel, Andrew Kylander-Clark y Ram Weinberger. "Towards in situ U–Pb dating of dolomite". Geochronology 3, n.º 1 (26 de mayo de 2021): 337–49. http://dx.doi.org/10.5194/gchron-3-337-2021.

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Abstract. Recent U–Pb dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has demonstrated that reasonable precision (3 %–10 %, 2σ) can be achieved for high-resolution dating of texturally distinct calcite phases. Absolute dating of dolomite, for which biostratigraphy and traditional dating techniques are very limited, remains challenging, although it may resolve many fundamental questions related to the timing of mineral-rock formation by syngenetic, diagenesis, hydrothermal, and epigenetic processes. In this study we explore the possibility of dating dolomitic rocks via recent LA-ICP-MS dating techniques developed for calcite. The in situ U–Pb dating was tested on a range of dolomitic rocks of various origins from the Cambrian to Pliocene age – all of which are from well-constrained stratigraphic sections in Israel. We present imaging and chemical characterization techniques that provide useful information on interpreting the resulting U–Pb ages and discuss the complexity of in situ dolomite dating in terms of textural features that may affect the results. Textural examinations indicate zonation and mixing of different phases at the sub-millimeter scale (< 1 µm), and thus Tera–Wasserburg ages represent mixed dates of early diagenesis and some later epigenetic dolomitization event(s). We conclude that age mixing at the sub-millimeter scale is a major challenge in dolomite dating that needs to be further studied and note the importance of matrix-matched standards for reducing uncertainties of the dated material.

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43

Punning, Jaan-Mati, Mati Ilomets y Tiiu Koff. "Possibilities for Detailed Dating of Peat Bog Deposits". Radiocarbon 35, n.º 3 (1993): 379–85. http://dx.doi.org/10.1017/s0033822200060380.

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Geochemical and palynological data as well as radiocarbon dating were used to study the peat bog deposits in Niinsarre bog, northeast Estonia. The aim of this study was to establish criteria for determining a detailed chronology, which is important, for example, in studying paleoevents and historical monitoring. In some cases, we can use cumulative pollen data, as well as cumulative chemical and peat bulk density data.

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44

Mueller, Ken y Paul Muzikar. "Correcting for Contamination in AMS 14C Dating". Radiocarbon 44, n.º 2 (2002): 591–95. http://dx.doi.org/10.1017/s0033822200031945.

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When using accelerator mass spectrometry (AMS) for radiocarbon dating, it is important to correct for carbon contamination that is added to the sample and the standard during chemical processing. We derive an equation for making this correction that generalizes previous work in several ways. We treat the case in which contaminating carbon is added during both the combustion step and graphitization step. Taking this two-stage contamination process into account is particularly important when only a fraction of the CO2 produced in the combustion is graphitized. We also allow for the fact that the 13C fractions of the sample, the standard, and the contaminants may be different.

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45

Komarova, Ya M., N. L. Aluker, V. V. Bobrov y N. V. Sorokina. "Thermoluminescent dating of archaeological pottery". Inorganic Materials 47, n.º 5 (mayo de 2011): 544–48. http://dx.doi.org/10.1134/s0020168511050128.

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46

Bersch, Michael G. "Electron Microprobe Dating of Uraninite from the Mcallister Pegmatite, Alabama". Microscopy and Microanalysis 5, S2 (agosto de 1999): 538–39. http://dx.doi.org/10.1017/s1431927600016019.

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In the early days of geochronology, attempts were made to date U-Th bearing rocks and minerals using the Pb-U-Th chemical method, but fundamental assumptions that all the lead was of radiogenic origin, and the system was closed, often were invalid. With the advent of the U-Th-Pb isotopic and common-lead methods of dating rocks and minerals, the chemical method was deemed clinically dead. However, several workers, for example, Montel et al., Suzuki and Adachi, have recently demonstrated new life for the chemical method. Using, the same theoretical basis as the chemical method, geologically reasonable dates often can be obtained by electron microprobe analysis of U-Th rich monazite (Ca-REE-U-Th phosphate). Other U- or Thrich minerals sometimes can be used to obtain microprobe U-Th-Pb dates, e.g., zircon, xenotime, uraninite.Microprobe U-Th-Pb dates of uraninites from the McAllister Ta-Sn pegmatite, Coosa County, Alabama, are reported here. The McAllister pegmatite is a NW-SE dike-like body in the western part of the Rockford granite pluton. Polished grain mounts were made from screened table runs of heavy mineral separates. Wodginite (Mn, Sn, Nb, Ta-oxide), tantalite-columbite, zircon, cassiterite comprise most of the grains in the samples. Uraninite occurs as inclusions, generally <0.01 mm, in these grains (Figure 1).U, Th, Pb concentrations were measured using a JEOL 8600 Superprobe. Operating conditions were 100 nA, 20 kV, and count times up to 200 seconds for peak plus background. The U Mβ, Th Mα, and Pb Mα peaks were measured. Standards were UO2, ThO2, and PbS.

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47

Goslar, Tomasz, Danuta Nawrocka y Justyna Czernik. "Foraminiferous Limestone in 14C Dating of Mortar". Radiocarbon 51, n.º 3 (2009): 987–93. http://dx.doi.org/10.1017/s0033822200034068.

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Mortar as a mixture of binder and aggregate can be reliably dated with radiocarbon if the applied preparation method allows one to eliminate unburnt carbonate fragments, bearing 14C-depleted carbon and causing overestimation of 14C age. To avoid these problems, separation of specific grain-size fractions of mortar and 14C analysis of the CO2 portions collected in different time intervals of the acid-leaching reaction is usually helpful. In the present paper, we demonstrate that the rate of the leaching reaction of mortars with dense carbonate aggregate differs from that of mortars with crumbled limestone and scattered shells (e.g. of foraminifera). Verification of the obtained 14C dates against historical sources shows that for mortars rich in foraminiferous limestone, a reaction rate-based chemical elimination of “dead carbon” may appear impossible.

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48

Wang, Hua, Hua Ying Liang y Bing Xiang Liu. "Rough Set of Optimized Probabilistic Neural Network in Identification of Blue and White Ceramic from Jingdezhen". Applied Mechanics and Materials 190-191 (julio de 2012): 164–67. http://dx.doi.org/10.4028/www.scientific.net/amm.190-191.164.

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The chemical composition is usually acquired by various scientific analyses in blue and white ceramics researches from Jingdezhen,then they are classified and catalogued by the calculation based on some proper mathematical model,finally the discrimination functions can be got. This paper introduces the rough set theory and probabilistic neural network for some of the basic concepts, and give the optimal probability rough set neural network method to establish the Jingdezhen blue and white porcelain dating model the basic steps and the pottery chemical composition data processing method, through the application examples, it shows that the methods of Jingdezhen blue and white dating of ceramics research results to achieve the expected purpose.

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49

Atsumi, Shin, Minoru Yoneda, Yasuyuki Shibata, Akiko Hokura y Izumi Nakai. "Chemical evaluation of the ABA pretreatment of charcoal samples for radiocarbon dating". Quaternary Research (Daiyonki-Kenkyu) 48, n.º 4 (2009): 289–94. http://dx.doi.org/10.4116/jaqua.48.289.

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50

French, Jason E., Larry M. Heaman y Thomas Chacko. "Feasibility of chemical U–Th–total Pb baddeleyite dating by electron microprobe". Chemical Geology 188, n.º 1-2 (agosto de 2002): 85–104. http://dx.doi.org/10.1016/s0009-2541(02)00074-8.

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