WorldWideScience

Sample records for u-series dated speleothem

  1. U-series dating and stable isotope records of speleothem records from the Scladina Cave (Belgium)

    Science.gov (United States)

    van der Lubbe, Jeroen; Bonjean, Dominique; Hellstrom, John; Verheyden, Sophie; Vonhof, Hubert

    2015-04-01

    The Scladina cave, situated in the village of Sclayn (Ardennes, Belgium) at the southern bank of the Meuse, is famous for its Neanderthal fossils and artefacts. The infilling of the cave consists of a succession of flowstone layers interbedded with reworked loess sediment from outside the cave. The younger flowstone layers correspond to interglacials MIS 5 and the Holocene, while the reworked loess sediments represent cooler conditions. By careful diagenetic screening, well-preserved speleothem material was selected for U-series dating and stable isotope analysis of calcite and fluid inclusions. The results provide important new constraints on the age of Neanderthal fossils and artefacts, and bracket the time periods with a hydroclimate favorable for speleothem growth. The combination of fluid inclusion and calcite isotope analysis documents climate variability in the interglacials at high temporal resolution.

  2. MOD-AGE - an algorithm for age-depth model construction; U-series dated speleothems case study

    Science.gov (United States)

    Hercman, H.; Pawlak, J.

    2012-04-01

    We present MOD-AGE - a new system for chronology construction. MOD-AGE can be used for profiles that have been dated by different methods. As input data, the system uses the following basic measurements: activities, atomic ratios or age, as well as depth measurement. Based on probability distributions describing the measurement results, MOD-AGE estimates the age~depth relation and its confidence bands. To avoid the use of difficult-to-meet assumptions, MOD-AGE uses nonparametric methods. We applied a Monte Carlo simulation to model age and depth values based on the real distribution of counted data (activities, atomic ratios, depths etc.). Several fitting methods could be applied for estimating the relationships; based on several tests, we decide to use LOESS method (locally weighted scatterplot smoothing). The stratigraphic correction procedure applied in the MOD-AGE program uses a probability calculus, which assumes that the ages of all the samples are correctly estimated. Information about the probability distribution of the samples' ages is used to estimate the most probable sequence that is concordant according to the superposition rule. MOD-AGE is presented as a tool for the chronology construction of speleothems that have been analyzed by the U-series method, and it is compared to the StalAge algorithm presented by D. Scholtz and D.L Hoffmann (2011). Scholtz, D., Hoffmann, D. L., 2011. StalAge - An algorithm designed for construction of speleothem age models. Quaternary Geochronology 6, 369-382.

  3. U-series disequilibrium dating of Quaternary carbonates

    International Nuclear Information System (INIS)

    Stirling, C.

    2006-01-01

    One of the key dating methods used in paleoclimate research utilizes the natural radioactive decay of uranium to thorium in archives containing U-bearing minerals, such as the calcium carbonate forming the skeletons of fossil corals and speleothems. More specifically, this chronometer, commonly referred to as the U-series dating method, is based on the decay of 238 U to its longest-lived intermediate daughters, 234 U and 230 Th, and subsequent decay through to stable isotopes of Pb. It is the respective 250,000 and 75,000 year half-lives of these daughter isotopes, which make the U-series system particularly useful for dating Quaternary climate events spanning the last 600,000 years of Earth's history. The U-series thus bridges the gap between the ∼45,000 year upper limit of conventional radiocarbon dating and the ∼200,000 year lower limit of K-Ar and 40 Ar- 39 Ar dating. 2 refs., 5 figs

  4. Uranium-series dating of gypsum speleothems: methodology and examples.

    Directory of Open Access Journals (Sweden)

    Sanna Laura

    2010-01-01

    Full Text Available The analytical problems of dating gypsum speleothems with the U-series technique are reviewed. Gypsum speleothems are, in general, very low in U content, challenging the limits of detection methods. Various approaches to dissolving gypsum and isolation of actinides from the matrix include ion-pairing dissolution with magnesium salts and using nitric acid. The most precise dating technique is Thermal Ionization Mass Spectrometry (TIMS, combined with Fe(OH3 scavenging and anionic exchange chromatography. Less satisfactory, but much quicker, is direct retention of actinides from HNO3 by means of TRU resin and MC-ICP-MS detection. We have tested these methods on gypsum speleothems from the Sorbas karst in Spain and from the Naica caves in Mexico.

  5. U-series dating using thermal ionisation mass spectrometry (TIMS)

    International Nuclear Information System (INIS)

    McCulloch, M.T.

    1999-01-01

    U-series dating is based on the decay of the two long-lived isotopes 238 U(τ 1/2 =4.47 x 10 9 years) and 235 U (τ 1/2 0.7 x 10 9 years). 238 U and its intermediate daughter isotopes 234 U (τ 1/2 = 245.4 ka) and 230 Th (τ 1/2 = 75.4 ka) have been the main focus of recently developed mass spectrometric techniques (Edwards et al., 1987) while the other less frequently used decay chain is based on the decay 235 U to 231 Pa (τ 1/2 = 32.8 ka). Both the 238 U and 235 U decay chains terminate at the stable isotopes 206 Pb and 207 Pb respectively. Thermal ionization mass spectrometry (TIMS) has a number of inherent advantages, mainly the ability to measure isotopic ratios at high precision on relatively small samples. In spite of these now obvious advantages, it is only since the mid-1980's when Chen et al., (1986) made the first precise measurements of 234 U and 232 Th in seawater followed by Edwards et al., (1987) who made combined 234 U- 230 Th measurements, was the full potential of mass spectrometric methods first realised. Several examples are given to illustrate various aspects of TIMS U-series

  6. U-series dating using thermal ionisation mass spectrometry (TIMS)

    Energy Technology Data Exchange (ETDEWEB)

    McCulloch, M.T. [Australian National University, Canberra, ACT (Australia). Research School of Earth Science

    1999-11-01

    U-series dating is based on the decay of the two long-lived isotopes{sup 238}U({tau}{sub 1/2}=4.47 x 10{sup 9} years) and {sup 235}U ({tau}{sub 1/2} 0.7 x 10{sup 9} years). {sup 238}U and its intermediate daughter isotopes {sup 234}U ({tau}{sub 1/2} = 245.4 ka) and {sup 230}Th ({tau}{sub 1/2} = 75.4 ka) have been the main focus of recently developed mass spectrometric techniques (Edwards et al., 1987) while the other less frequently used decay chain is based on the decay {sup 235}U to {sup 231}Pa ({tau}{sub 1/2} = 32.8 ka). Both the {sup 238}U and {sup 235}U decay chains terminate at the stable isotopes {sup 206}Pb and {sup 207}Pb respectively. Thermal ionization mass spectrometry (TIMS) has a number of inherent advantages, mainly the ability to measure isotopic ratios at high precision on relatively small samples. In spite of these now obvious advantages, it is only since the mid-1980`s when Chen et al., (1986) made the first precise measurements of {sup 234}U and {sup 232}Th in seawater followed by Edwards et al., (1987) who made combined {sup 234}U-{sup 230}Th measurements, was the full potential of mass spectrometric methods first realised. Several examples are given to illustrate various aspects of TIMS U-series 9 refs., 3 figs.

  7. Assessment of the lower ESR dating range in Greek speleothems

    International Nuclear Information System (INIS)

    Bassiakos, Y.

    2001-01-01

    Pilot ESR dating studies on geologically young calcitic sinters were carried out, aiming at assessment of the lower ESR dating range in characteristic Greek speleoenvironments. Five stalactites were dated, coming from an ancient mining gallery, idle for the last 2,500 years, found on Siphnos island (Aegean). The calculated ages range between 1,7-2,0 ka. Medium to low measured external dose rates (aprox. 900 μGy/a) and very low measured radioelement concentration in samples are very usual in the Mediterranean environments. The study concludes that ESR dating of speleothems younger than two millenia is practically unattainable. Some geoarchaeological implications of the obtained ages are discussed. (author)

  8. Combined ESR and U-series isochron dating of fossil tooth from Longgupo cave

    International Nuclear Information System (INIS)

    Han Fei; Yin Gongming; Liu Chunru; Jean-Jacques Bahain

    2012-01-01

    Background: In ESR and luminescence archaeological dating, the assessment of external radiation dose rate is one of the constant sources of uncertainty because of its variation in the past time and it cannot be determined accurately using the present-day measurements. Purpose: ESR isochron protocol was proposed to solve this uncertainty for the tooth samples. This protocol is applicable wherever multiple samples with different internal doses have all experienced a common external dose. The variable uranium concentration of tooth samples makes it possible to plot the equivalent dose versus the internal dose rate of each sample, and the slope of isochron line gives hence the age. For isochron dating of teeth, combined ESR/U-series dating analysis must be done together with isochron protocol. Methods: In this study, we try to use combined ESR/U-series isochron method on 5 tooth samples collected from immediate adjacent square in layer C Ⅲ'6 of Longgupo archaeological site, Chongqing, China. Combined ESR/U-series analysis with in situ external dose rate shows recent uranium uptake of all the samples. Results: The time-averaged external dose rate was iterative calculated by isochron protocol, and gives an isochron age of 1.77±0.09 Ma for layer C Ⅲ'6, which consistent with the mean US-ESR ages of 5 samples (1.64+0.16/-0.21 Ma) in the error range. The calculated time-averaged external dose rate(∼807 μGy/a) was basically in agreement with the in situ measured gamma dose rate value (8.50 μGy/a) in 2006, indicating the geochemical alterations may not occurred or do not affect the environmental dose rate obviously during the burial history. Conclusions: This study indicates the potential of solving both internal and external dose rate problems of ESR dating of fossil teeth by combining with U-series analysis and isochron protocol. (authors)

  9. First 226Ra- 210Pb dating of a young speleothem

    Science.gov (United States)

    Condomines, M.; Rihs, S.

    2006-10-01

    Whereas the method based on the decrease of excess 210Pb has already been used to date young (Age determination of recent cave deposits using excess 210Pb — A new technique, Geophys. Res. Lett. 20 (1993) 603-606.]), this paper presents the first dating of a speleothem through the 226Ra- 210Pb method. Dating of a young hydrothermal stalagmite from the Mt Cornadore cave (St Nectaire, French Massif Central) was made possible by the high 226Ra and negligible 210Pb contents of such carbonates, formed by precipitation from CO 2-rich thermal waters. ( 210Pb/ 226Ra) ratios regularly increase with depth along the axis of the 33 cm long stalagmite. The age-depth relationship can be interpreted by two main phases of growth, with high but variable axial growth rates of 5.3 mm/yr from 1909 to 1967, and 2.6 mm/yr from 1967 to 1989 (alternatively, the oldest phase can be subdivided in three episodes with growth rates varying from 2 to 7 mm/yr). Thin-section examination reveals the presence of numerous laminae, indicating infra-annual variations. We suggest that this fine layered structure might reflect short-term fluctuations in drip waters, possibly induced by near-surface mixing between thermal and ground waters, and ultimately linked to the pluviometry. A detailed examination of this laminated structure combined with 226Ra- 210Pb dating could thus provide a high-resolution record of local paleohydrological fluctuations.

  10. Modeling Magma Mixing: Evidence from U-series age dating and Numerical Simulations

    Science.gov (United States)

    Philipp, R.; Cooper, K. M.; Bergantz, G. W.

    2007-12-01

    -pairs, heterogeneity of particle populations is large. After one overturn event, even the "thin section scale" can contain phenocrysts that derive from the entire magmatic system. We combine these results with time scale information from U-series plagioclase age dating. Apparent crystal residence times from the most evolved and therefore least hybridized rocks for the 1846/47 and 1932 eruptions of Volcan Quizapu are about 5000 and about 3000 yrs, respectively. Based on whole rock chemistry as well as textural and crystal-chemical data, both eruptions tapped the same reservoir and therefore should record similar crystal residence times. Instead, the discordance of these two ages can be explained by magma mixing as modeled above, if some young plagioclase derived from the andesitic recharge magma which triggered the 1846/47 AD eruption got mixed into the dacite remaining in the reservoir after eruption, thus lowering the apparent crystal residence time for magma that was evacuated from the reservoir in 1932.

  11. U-series component dating for late pleistocene basalt Longgang, Jilin province

    International Nuclear Information System (INIS)

    Yu Fusheng; Yuan Wanming; Han Song

    2003-01-01

    Longgang volcanic swarm belongs to one of volcanic areas which have been active since modern times. In view of multiple eruptions during histories, it is very important to determine age of every eruption for evaluating volcanic hazards. The alkaline basalt samples taken from Dayizishan and diaoshuihu are analyzed by U-series component method, after magnetic separation. The ages of the two samples are (71 ± 9) ka, (106 ± 13) ka before presence, respectively. These data indicate that there exist intensively eruptive activities during late Pleistocene

  12. Palaeoclimatic and geomorphic implications of 230Th/ 234U dates on speleothems from Britain

    International Nuclear Information System (INIS)

    Atkinson, T.C.; Harmon, R.S.; Smart, P.L.; Waltham, A.C.

    1978-01-01

    It is stated that a priori arguments and empirical evidence both suggest that widespread deposition of calcite in caves takes place in non-glacial climatic conditions. Radiometric dates from calcite speleothems in Britain indicate deposition before 170,000 yr b.p., during an interglacial around 90 to 140,000 yr b.p., an interstadial at 60,000 yr b.p., and in the late Devensian and Holocene. The positions of speleothems within caves allow minimum ages to be estimated for the past water tables and associated surface landforms. The main erosion of the Yorkshire Dales is shown to date from 400,000 yr b.p., while Cheddar Gorge in the Mendip Hills has been deepened by 70 m during the last 400 millenia. (author)

  13. U-series dating of Paleolithic art in 11 caves in Spain.

    Science.gov (United States)

    Pike, A W G; Hoffmann, D L; García-Diez, M; Pettitt, P B; Alcolea, J; De Balbín, R; González-Sainz, C; de las Heras, C; Lasheras, J A; Montes, R; Zilhão, J

    2012-06-15

    Paleolithic cave art is an exceptional archive of early human symbolic behavior, but because obtaining reliable dates has been difficult, its chronology is still poorly understood after more than a century of study. We present uranium-series disequilibrium dates of calcite deposits overlying or underlying art found in 11 caves, including the United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage sites of Altamira, El Castillo, and Tito Bustillo, Spain. The results demonstrate that the tradition of decorating caves extends back at least to the Early Aurignacian period, with minimum ages of 40.8 thousand years for a red disk, 37.3 thousand years for a hand stencil, and 35.6 thousand years for a claviform-like symbol. These minimum ages reveal either that cave art was a part of the cultural repertoire of the first anatomically modern humans in Europe or that perhaps Neandertals also engaged in painting caves.

  14. Statistical U-Th dating results of speleothem from south Europe and the orbital-scale implication

    Science.gov (United States)

    Hu, H. M.

    2016-12-01

    Reconstructing of hydroclimate in the Mediterranean on an orbital time scale helps improve our understanding of interaction between orbital forcing and north hemisphere climate. We collected 180 speleothem subsamples from Observatoire Cave (Monaco), Prince Cave (south France), Chateaueuf Cave (South France), Arago Cave (South France), and Basura Cave (North Italy) during 2013 to 2015 C.E. Uranium-thorium dating were conducted in the High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), National Taiwan University. The results show that most of the speleothem formed during interglacial periods, particularly in marine isotope stage (MIS) 1, 5, and 11. However, only a few speleothem were dated between 180 to 250 thousand years ago (ka). The interval is approximately equivalent to MIS 7, which is a period with contrasting orbital parameters compared to MIS1, 5, and 11. Our statistical dating result implies that the orbital-scale humid/dry condition in southern Europe could be dominantly controlled by orbital forcing.

  15. High-resolution U-series dates from the Sima de los Huesos hominids yields 600 +∞-66: implications for the evolution of the early Neanderthal lineage

    Science.gov (United States)

    Bischoff, James L.; Williams, Ross W.; Rosenbauer, Robert J.; Aramburu, Arantza; Arsuaga, Juan Luis; Garcia, Nuria; Cuenca-Bescos, Gloria

    2007-01-01

    The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mud-breccia underlying an accumulation of the Middle Pleistocene cave bear (Ursus deningeri). We report here on new high-precision dates on the recently discovered speleothem SRA-3 overlaying human bones within the Sima de los Huesos. Earlier analyses of this speleothem by TIMS (thermal-ionization mass-spectrometry) showed the lower part to be indistinguishable from internal isotopic equilibrium at the precision of the TIMS instrumentation used, yielding minimum age of 350 kyr (kyr = 103 yr before present). Reanalysis of six samples of SRA-3 by inductively-coupled plasma-multicollector mass-spectrometry (ICP-MS) produced high-precision analytical results allowing calculation of finite dates. The new dates cluster around 600 kyr. A conservative conclusion takes the lower error limit ages as the minimum age of the speleothem, or 530 kyr. This places the SH hominids at the very beginnings of the Neandertal evolutionary lineage.

  16. Dating of speleothems in non-karst caves - methodological aspects and practical application, Polish Outer Carpathians case study

    Czech Academy of Sciences Publication Activity Database

    Urban, J.; Margielewski, W.; Hercman, H.; Žák, Karel; Zernitska, V.; Pawlak, J.; Schejbal-Chwastek, M.

    2015-01-01

    Roč. 59, Supplement 1 (2015), s. 185-210 ISSN 0372-8854 Institutional support: RVO:67985831 Keywords : non-karst caves * speleothem dating * landslide * Polish Outer Carpathians Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.103, year: 2015

  17. Coral indicators of past sea-level change: A global repository of U-series dated benchmarks

    Science.gov (United States)

    Hibbert, Fiona D.; Rohling, Eelco J.; Dutton, Andrea; Williams, Felicity H.; Chutcharavan, Peter M.; Zhao, Cheng; Tamisiea, Mark E.

    2016-08-01

    Fossil corals provide valuable data for reconstructing past sea levels, as they are often well preserved in the fossil record and can be dated with U-series methods. Here we present a global and internally consistent database of Usbnd Th dated fossil coral sea-level indicators, including full consideration of all (known) associated uncertainties (both vertical and chronological). We include carefully determined taxon-specific depth distributions, rather than blanket depth uncertainty terms as used in most previous work. This is based on a synthesis of extensive modern ecological information on depth ranges. These ranges are found to be spatially variable (between ocean basins, between regions, and on sub-regional scales) because depth itself is not limiting - instead, depth distributions arise from complex physical, chemical, and biological interactions with coral-reef growth, distribution, and composition. One of the main causes for recognition of the greater depth-variability of coral taxa has been the routine inclusion of deep-diving and ROV surveys in coral ecological studies over the past few decades, which has broken through the "shallow-water" bias of early surveys by adding frequent observations on deeper occurrences (although more are needed). It is also clear from our assessment that coral habitat-depth distributions must be determined on the species level to reduce uncertainties in reconstructions of past sea levels, and that application to sea-level studies then requires these studies also to identify fossil corals to the species level. Samples identified only to the genus level give rise to wide uncertainties in habitat depth and, hence, sea level. Our database contains extensive metadata to assist evaluations of dating quality, as well as geomorphic and stratigraphic metadata. We demonstrate with examples how such metadata can help to evaluate sea-level reconstructions, for example by identifying outlier points. One example discusses the Last

  18. Dating of the middle Palaeolithic site of Payre (Ardeche): new radiometric data (U-series and ESR methods)

    International Nuclear Information System (INIS)

    Masaoudi, H.; Falgueres, Ch.; Bahain, J.J.; Moncel, M.H.

    1997-01-01

    The site of Payre is located in Ardeche. Several archaeological layers containing lithic artefacts of Middle Palaeolithic were found. These artefacts lie associated with carbonate formations which are good chronostratigraphic markers. The U-series and ESR methods on bones and stalagmitic floors placed the human occupation between isotopic marine stages 7 and 4. (authors)

  19. Contributions to Th-230/U-234 dating of speleothems; comparison of the results with those of other absolute dating methods

    International Nuclear Information System (INIS)

    Hennig, G.J.

    1979-01-01

    Calcite speleothems, e.g. stalagmites, have been investigated by α-spectrometry using Si-surface boundary layer detectors after radiochemical separation. The findings are compared with those of other physical/chemical/nuclear physics techniques. (HP) [de

  20. Effects of dating errors on nonparametric trend analyses of speleothem time series

    Directory of Open Access Journals (Sweden)

    M. Mudelsee

    2012-10-01

    Full Text Available A fundamental problem in paleoclimatology is to take fully into account the various error sources when examining proxy records with quantitative methods of statistical time series analysis. Records from dated climate archives such as speleothems add extra uncertainty from the age determination to the other sources that consist in measurement and proxy errors. This paper examines three stalagmite time series of oxygen isotopic composition (δ18O from two caves in western Germany, the series AH-1 from the Atta Cave and the series Bu1 and Bu4 from the Bunker Cave. These records carry regional information about past changes in winter precipitation and temperature. U/Th and radiocarbon dating reveals that they cover the later part of the Holocene, the past 8.6 thousand years (ka. We analyse centennial- to millennial-scale climate trends by means of nonparametric Gasser–Müller kernel regression. Error bands around fitted trend curves are determined by combining (1 block bootstrap resampling to preserve noise properties (shape, autocorrelation of the δ18O residuals and (2 timescale simulations (models StalAge and iscam. The timescale error influences on centennial- to millennial-scale trend estimation are not excessively large. We find a "mid-Holocene climate double-swing", from warm to cold to warm winter conditions (6.5 ka to 6.0 ka to 5.1 ka, with warm–cold amplitudes of around 0.5‰ δ18O; this finding is documented by all three records with high confidence. We also quantify the Medieval Warm Period (MWP, the Little Ice Age (LIA and the current warmth. Our analyses cannot unequivocally support the conclusion that current regional winter climate is warmer than that during the MWP.

  1. {sup 230}Th/U-dating of a late Holocene low uranium speleothem from Cuba

    Energy Technology Data Exchange (ETDEWEB)

    Fensterer, Claudia; Mangini, Augusta [Forschungsstelle Radiometrie, Heidelberg Academy of Sciences, Im Neuenheimer Feld 229, 69120 Heidelberg (Germany); Scholz, Denis; Hoffmann, Derik [School of Geographical Sciences, University of Bristol, University Road, BS8 1SS, Bristol (United Kingdom); Pajon, Jesus M, E-mail: Claudia.Fensterer@iup.uni-heidelberg.d [Department of Archaeology, Cuban Institute of Anthropology, Amargura No. 203, e/n Habana y Aguiar, Ciudad de La Habana, CP: 10 100 (Cuba)

    2010-03-15

    We present 22 U-series ages for a stalagmite from north-western Cuba based on multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and thermal ionisation mass spectrometry (TIMS). Our results reveal that the stalagmite continuously grew within the last {approx}1400a. Low uranium content of the sample and thus, extremely low {sup 230}Th concentrations limit the precision and accuracy of {sup 230}Th/U-dating by TIMS. Samples measured by MC-ICPMS show a high variability of {sup 232}Th content along the growth axis with some sections significantly affected by initial {sup 230}Th from a detrital phase. An a-priori bulk earth ratio for ({sup 238}U/{sup 232}Th) cannot be used to accurately account for this initial {sup 230}Th. Using an age model based on the {sup 230}Th/U ages determined on samples with low or negligible {sup 232}Th concentration, we find that the ({sup 238}U/{sup 232}Th) activity ratio of the detrital phase is an order of magnitude larger than the bulk earth value, indicating the importance of an accurately determined correction factor.

  2. 230Th/U-dating of a late Holocene low uranium speleothem from Cuba

    International Nuclear Information System (INIS)

    Fensterer, Claudia; Mangini, Augusta; Scholz, Denis; Hoffmann, Derik; Pajon, Jesus M

    2010-01-01

    We present 22 U-series ages for a stalagmite from north-western Cuba based on multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and thermal ionisation mass spectrometry (TIMS). Our results reveal that the stalagmite continuously grew within the last ∼1400a. Low uranium content of the sample and thus, extremely low 230 Th concentrations limit the precision and accuracy of 230 Th/U-dating by TIMS. Samples measured by MC-ICPMS show a high variability of 232 Th content along the growth axis with some sections significantly affected by initial 230 Th from a detrital phase. An a-priori bulk earth ratio for ( 238 U/ 232 Th) cannot be used to accurately account for this initial 230 Th. Using an age model based on the 230 Th/U ages determined on samples with low or negligible 232 Th concentration, we find that the ( 238 U/ 232 Th) activity ratio of the detrital phase is an order of magnitude larger than the bulk earth value, indicating the importance of an accurately determined correction factor.

  3. U-Th dating of broken speleothems from Cacahuamilpa cave, Mexico: Are they recording past seismic events?

    Science.gov (United States)

    Méjean, Pauline; Garduño-Monroy, Victor-Hugo; Pinti, Daniele L.; Ghaleb, Bassam; Bouvier, Laura; Gomez-Vasconcelos, Martha G.; Tremblay, Alain

    2015-01-01

    Cacahuamilpa cave is one of the largest karst systems in Central Mexico. The cave contains numerous massive speleothems broken and fallen following oriented directions, damaged during cataclysmic geological events. One fallen and two broken speleothems were sampled in the Cacahuamilpa cave for dating the rupture event using measured U-Th disequilibrium ages. A total of eight small carbonate cores were drilled perpendicular and longitudinal to the rupture surface. Results showed three groups of ages (weighted average): 0.95 ± 0.02 ka, 28.8 ± 0.2 ka and 88.0 ± 0.7 ka. This indicates that the construction of the Cacahuamilpa karst system, for which no absolute ages existed before this study, initiated at least since Late Pleistocene. The first two groups of ages might be related to two distinct episodes of intense seismic activity. Calculated minimum horizontal ground acceleration and frequency values of the seismic events needed to create the rupture of the stalagmites dated at 0.95 ± 0.02 ka and 28.8 ± 0.2 ka range between 1.3 and 2.0 m s-2 and between 13.4 and 20.8 Hz, respectively. These parameters are compatible with earthquakes of magnitude equal or higher than 7 M, with an epicentral distance between 50 and 100 km from the Cacahuamilpa cave. The stalagmite rupture dated at 88.0 ± 0.7 ka might result from the invasion of the cave by one of the older lahars deposits of the nearby volcano Nevado del Toluca, and successively fell by gravity instability.

  4. U-Th dating of speleothems to investigate the evolution of limestone caves in the Gunung Mulu National Park, Sarawak, Malaysia

    OpenAIRE

    Moseley, Gina E.; Richards, David A.; Smith, Christopher; Smart, Peter L.; Hoffmann, Dirk L.; Farrant, Andrew R.

    2013-01-01

    The Gunung Mulu National Park, Sarawak, Malaysia has been a focus of scientific research and exploration for several decades. Previous work investigated the relationship between fluvial incision into the limestone massif and the chronological evolution of the 500m-deep network of cave passages. This study involved analyses of newly available speleothem material using state-of-the-art U-Th dating methods and assessment of the potential for extension of the chronological record using U-Pb datin...

  5. Study of two new methods of geochronometry: dating method of carbonaceous formations by U-series disequilibrium gamma spectrometry; ESR dating method of rich U-content fossil dental enamel

    International Nuclear Information System (INIS)

    Ma, Jean-Luc

    1984-01-01

    First, the U-series disequilibrium dating method was re-examined using non-destructive γ-spectrometry. A new low-background (≤ 10 ppb U- equivalent) Ge-HP γ-spectrometer has been used to date travertine with small U-content (∼ 0.1 ppm) and low (≤ 5%) Th/U , content, by comparison with old-limestone γ-spectra. Second, a new ESR dating method has been developed using fossil dental enamel which is rich in U-content (10 - 100 ppm). Both methods were applied to Arago Cave (Tautavel, France): - with an ionium-age of 120 ka (10%), the upper travertine seems to have been set up during the Riss-deglaciation period. - the high (∼ 50%) Th/U-content samples of the intermediate travertine are un-datable. - the ESR-age of EQUUS mosbachensis enamel is 400 ka (10%) for the G-soil of Arago. XXI H. erectus, and 600 ka (10%) for the Q-soil above (- 1 m) of the lower travertine of which Io-age is older than 350 ka. (author)

  6. The Sima de los Huesos hominids date to beyond U/Th equilibrium (>350 kyr) and perhaps to 400-500 kyr: New radiometric dates

    Science.gov (United States)

    Bischoff, J.L.; Shamp, D.D.; Aramburu, Arantza; Arsuaga, J.L.; Carbonell, E.; Bermudez de Castro, Jose Maria

    2003-01-01

    The Sima de los Huesos site of the Atapuerca complex near Burgos, Spain contains the skeletal remains of at least 28 individuals in a mud breccia underlying an accumulation of the Middle Pleistocene cave bear (U. deningeri). Earlier dating estimates of 200 to 320 kyr were based on U-series and ESR methods applied to bones, made inaccurate by unquantifiable uranium cycling. We report here on a new discovery within the Sima de los Huesos of human bones stratigraphically underlying an in situ speleothem. U-series analyses of the speleothem shows the lower part to be at isotopic U/Th equilibrium, translating to a firm lower limit of 350 kyr for the SH hominids. Finite dates on the upper part suggest a speleothem growth rate of c. 1 cm/32 kyr. This rate, along with paleontological constraints, place the likely age of the hominids in the interval of 400 to 600 kyr. ?? 2002 Elsevier Science Ltd. All rights reserved.

  7. On the limits of using combined U-series/ESR method to date fossil teeth from two Early Pleistocene archaeological sites of the Orce area (Guadix-Baza basin, Spain)

    International Nuclear Information System (INIS)

    Duval, Mathieu; Falgueres, Christophe; Bahain, Jean-Jacques; Shao, Qingfeng; Grun, Rainer; Aubert, Maxime; Dolo, Jean-Michel; Agusti, Jordi; Martinez-Navarro, Bienvenido; Palmqvist, Paul; Toro-Moyano, Isidro

    2012-01-01

    The combined U-series/electron spin resonance (ESR) dating method was applied to nine teeth from two Early Pleistocene archaeological sites located in the Orce area (Guadix-Baza Basin, Southern Spain): Fuente Nueva-3 (FN-3) and Barranco Leon (BL). The combination of bio-stratigraphy and magneto-stratigraphy places both sites between the Olduvai and Jaramillo sub-chrons (1.78-1.07 Ma). Our results highlight the difficulty of dating such old sites and point out the limits of the combined U-series/ ESR dating method based on the US model. We identified several sources of uncertainties that may lead to inaccurate age estimates. Seven samples could not be dated because the dental tissues had ( 230 Th/ 234 U) activity ratios higher than equilibrium, indicating that uranium had probably leached from these tissues. It was however possible to calculate numerical estimates for two of the teeth, both from FN-3. One yielded a Middle Pleistocene age that seems to be strongly underestimated; the other provided an age of 1.19±0.21 Ma, in agreement with data obtained from independent methods. The latter result gives encouragement that there are samples that can be used for routine dating of old sites. (authors)

  8. Speleothem evidence for the greening of the Sahara and its implications for the early human dispersal out of sub-Saharan Africa

    Science.gov (United States)

    El-Shenawy, Mohammed I.; Kim, Sang-Tae; Schwarcz, Henry P.; Asmerom, Yemane; Polyak, Victor J.

    2018-05-01

    Although there is a consensus that there were wet periods (greening events) in the Sahara in the past, the spatial extent and the timing of these greening events are still in dispute, yet critical to our understanding of the early human dispersal out of Africa. Our U-series dates of speleothems from the Northeastern Sahara (Wadi Sannur cave, Egypt) reveal that the periods of speleothem growth were brief and restricted to the interglacial Marine Isotope Stages MIS 5.5, MIS 7.3, and the early MIS 9 with a remarkable absence of the Holocene deposition of speleothems. These growth periods of Wadi Sannur cave speleothems correspond to periods of high rainfall and spread of vegetation (green Sahara). Distinct low δ18O values of speleothems indicate a distal moisture source that we interpret to be the Atlantic Ocean. These two lines of evidence from the Wadi Sannur speleothems thus suggest that maximal northward shifts in the West African monsoon system occurred during the growth periods of the speleothems, leading to greening of the Sahara, facilitating human migration into Eurasia. The periods of speleothem growth at Wadi Sannur cave are contemporaneous with important archeological events: (1) the earliest occurrence of the Middle Stone Age assemblages and Homo sapiens in North Africa (Jebel Irhoud), suggesting wide spread of greening conditions over the East-West transect of the Sahara, (2) the sharp technological break between the Acheulo-Yabrudian and the Mousterian industries, and (3) the arrival of Homo sapiens in Levant, indicating a key role of the Sahara route in early human dispersal out of Africa.

  9. Age spans of some Indian speleothems

    International Nuclear Information System (INIS)

    Yadava, M.G.; Ramesh, R.; Polyak, V.J.; Asmerom, Y.

    2009-01-01

    In recent years, research on speleothems (minerals growing in caves, i.e. stalactites, stalagmites and flowstones) have shown that these have potential to provide records of past climate and environmental changes. Speleothems have several advantages compared to other high-resolution land archives (e.g., tree rings and lake sediments). Firstly, these are unaffected by natural erosion processes yielding long records of climate variability. Secondly, precise chronology by U-Th mass spectrometry is possible now. Prior to the advent of mass spectrometry (late 1980s), radiocarbon decay method was applied to date young samples (<40 kyr) and U-Th-alpha-counting method was adopted for older samples. In comparison with radiocarbon dates uranium series dates are absolute ages and no calibration is required. In India, palaeoclimate research using speleothem is in infancy, some work has been reported from Himalaya, central India and Peninsular India, with oxygen isotopes being used as monsoon proxy. Five speleothems from four Indian caves have been dated by U- Th method to estimate their ages and growth durations. Results indicate that these grew during various time intervals in Holocene and late Pleistocene

  10. Speleothem Paleoclimate Records from the Floridian Panhandle

    Science.gov (United States)

    Froelich, P. N.; Kowalczk, A. J.; McCardle, D.; Tibbetts, N.

    2007-12-01

    Geochemical time-series constructed from speleothem records provide a high resolution view into paleoclimate conditions temporally unmatched by deep ocean sediment and ice core records. The potential of speleothem records is vast with immense spatial and temporal resolution. One surprise to the speleothem paleoclimate community is the absence of high resolution speleothem isotope and trace element records from Florida, an area of extensive karstic geology, a plethora of caves, and monsoon-like climate. Two stalagmites collected from Brooks Quarry Cave, recently opened in Marianna, FL will provide one of the first Holocene speleothem climate records from the Southeast. Speleothem BC-1 is a 71 cm calcite stalagmite collected in situ. Speleothem BC-2 is a 6.1 cm stalagmite collected inside the quarried entrance to the cave. Both dripstones are banded and laminated at what appear to be 11-year cycles (dating in progress). If these are annual "sparves" (speleothem varves), the growth rates are approximately 100 μm per year. BC-1 would extend through much of the Holocene. RGB scans along the polished length of the growth axis reveal color cyclicity related to bundles of these bands. Isotope records from BC-2 reveal a multi-year record showing a variation of -2.7 ‰ to -6 ‰ in δ18O and -3.7 ‰ to -9.1‰ in δ13C, with no correlation between the two. High resolution multi-element laser ablation scans across 8 "sparves" (2.3 mm length) reveals co-variation in U and Ba with other elements showing weaker banding correlations with "clays" (Si, Fe, Mn, Ce, Rb). Photomicrographs of the laser tracks show correlation of visible "sparves" to chemical variations. Medical CT imaging techniques were applied to sample BC-1using a GE Lightspeed Plus CT scanner at maximum power (140 kV, 565 mA) and medium resolution (0.6 mm per scan slice) to view density differences and pore spaces inside the calcite matrix. CT technology reveals a porous nature of the calcite matrix in the lower

  11. Numerical dating of a Late Quaternary spit-shoreline complex at the northern end of Silver Lake playa, Mojave Desert, California: A comparison of the applicability of radiocarbon, luminescence, terrestrial cosmogenic nuclide, electron spin resonance, U-series and amino acid racemization methods

    Science.gov (United States)

    Owen, L.A.; Bright, Jordon; Finkel, R.C.; Jaiswal, M.K.; Kaufman, D.S.; Mahan, S.; Radtke, U.; Schneider, J.S.; Sharp, W.; Singhvi, A.K.; Warren, C.N.

    2007-01-01

    A Late Quaternary spit-shoreline complex on the northern shore of Pleistocene Lake Mojave of southeastern California, USA was studied with the goal of comparing accelerator mass spectrometry (AMS) radiocarbon, luminescence, electron spin resonance (ESR), terrestrial cosmogenic radionuclide (TCN) surface exposure, amino acid racemization (AAR) and U-series dating methods. The pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi-method approach. TCN surface exposure ages (mostly ???20-30 ka) record the initial erosion of shoreline benches, whereas radiocarbon ages on shells (determined in this and previous studies) within the spit, supported by AAR data, record its construction at fluctuating lake levels from ???16 to 10 ka. Luminescence ages on spit sediment (???6-7 ka) and ESR ages on spit shells (???4 ka) are anomalously young relative to radiocarbon ages of shells within the same deposits. The significance of the surprisingly young luminescence ages is not clear. The younger ESR ages could be a consequence of post-mortem enrichment of U in the shells. High concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single-sample U-series dating. Detailed comparisons such as this provide one of the few means of assessing the accuracy of Quaternary dating techniques. More such comparisons are needed. ?? 2007 Elsevier Ltd and INQUA.

  12. Age constraints for Palaeolithic cave art by U-Th dating of thin carbonate crusts

    Science.gov (United States)

    Hoffmann, Dirk; Pike, Alistair; Garcia-Diez, Marcos; Pettitt, Paul; Zilhão, João

    2015-04-01

    U-series dating is an important geochronological tool which is widely applied for instance in speleothem based palaeoclimate research. It has also great potential to provide age constraints for Archaeology, especially for sites or artefacts in cave environments. We present our methods to conduct precise U-Th dating of calcite crusts that formed on top of cave paintings. Recent developments in multi-collector (MC) inductively coupled plasma mass spectrometry (ICPMS) U-series dating greatly improved the precision of this method, and sample sizes needed to obtain reliable results were significantly reduced. Based on these developments the U-series technique can be applied for accurate dating of thin calcite crusts covering cave art at many sites, while taking care not to harm the art underneath. The method provides minimum ages for the covered art and, where possible, also maximum ages by dating the flowstone layer the art is painted on. The U-Th method has been used in a number of recent projects to date calcite precipitates above and occasionally below cave paintings in Spain. Initial results from Cantabria have shown that the earliest dated paintings are older than 41.4 ± 0.6 ka, dating at least to the Early Aurignacian period and present a far longer chronology than that based so far on radiocarbon dating. Here we outline our methodology and the steps we take to demonstrate the reliability of U-Th dates, and present some recent results of our ongoing U-Th dating programme.

  13. Direct Measurement of Initial 230TH/ 232TH Ratios in Central Texas Speleothems for More Accurate Age Determination

    Science.gov (United States)

    Wortham, B. E.; Banner, J. L.; James, E.; Loewy, S. L.

    2013-12-01

    Speleothems, calcite deposits in caves, preserve a record of climate in their growth rate, isotope ratios and trace element concentrations. These variables must be tied to precise ages to produce pre-instrumental records of climate. The 238U-234U- 230Th disequilibrium method of dating can yield precise ages if the amount of 230Th from the decay of radiogenic 238U can be constrained. 230Th in a speleothem calcite growth layer has two potential sources - 1) decay of radioactive 238U since the time of growth of the calcite layer; and 2) initial detrital 230Th, incorporated along with detrital 232Th, into the calcite layer at the time it grew. Although the calcite lattice does not typically incorporate Th, samples can contain impurities with relatively high Th contents. Initial 230Th/232Th is commonly estimated by assuming a source with bulk-Earth U/Th values in a state of secular equilibrium in the 238U-decay chain. The uncertainty in this 230Th/232Th estimate is also assumed, typically at +/-100%. Both assumptions contribute to uncertainty in ages determined for young speleothems. If the amount of initial detrital 230Th can be better quantified for samples or sites, then U-series ages will have smaller uncertainties and more precisely define the time series of climate proxies. This study determined the initial 230Th/232Th of modern calcite to provide more precise dates for central Texas speleothems. Calcite was grown on glass-plate substrates placed under active drips in central Texas caves. The 230Th/232Th of this modern calcite was determined using thermal ionization mass spectrometry. Results show that: 1) initial 230Th/232Th ratios can be accurately determined in these young samples and 2) measuring 230Th/232Th reduces the uncertainties in previously-determined ages on stalagmites from under the same drips. For example, measured initial 230Th/232Th in calcite collected on substrates from different locations in the cave at Westcave Preserve are 15.3 × 0.67 ppm

  14. Radiation-induced paramagnetic species in natural calcite speleothems

    International Nuclear Information System (INIS)

    Rossi, A.M.; Poupeau, G.

    1989-01-01

    The ESR natural spectrum of humic-free speleothem calcite single crytals in the region of g = 2.0000 is a composite of lines from 4 radiogenic species, in addition to Mn ++ lines. Laboratory irradiation causes appearrance of three more species. Use of isotropic F species (g = 2.0003) for dating is possible if specific cautions are followed. (author) [pt

  15. Speleothem microstructure/speleothem ontogeny: a review of Western contributions

    Directory of Open Access Journals (Sweden)

    White William B.

    2012-07-01

    Full Text Available Mineral ontogeny is the study of the growth and development of mineral deposits in general and, in the present context, speleothems in particular. Previous researchers, mainly in Russia, have developed a nomenclatural hierarchy based on the forms and habits of individual crystals and the assembly of individual crystals into both monomineralic and polymineralic aggegates (i.e. speleothems. Although investigations of the growth processes of speleothems are sparse, there is a large literature on growth processes of speleothem minerals and related crystals in the geochemical and materials science literature. The purpose of the present paper is to sort through the various concepts of crystal growth and attempt to relate these to observations on speleothems and to the Russian conceptual framework of mineral ontogeny. For calcite, the most common mineral in speleothems, the activation energy for two dimensional nucleation (required for the growth of large single crystals is almost the same as the activation energy for three- dimensional nucleation (which would result in the growth of many small crystals. Calcite growth is highly sensitive to minor impurities that may poison growth in certain crystallographic directions or may poison growth altogether. Extensive recent research using the atomic force microscope (AFM provides many details of calcite growth including the transition from growth on screw dislocations to growth by two-dimensional nucleation. The deposition of aragonite speleothems requires metastable supersaturation curve and is usually ascribed to the impurities Mg2+ and Sr2+. AFM studies reveal that Mg2+ poisons calcite growth by blocking deposition sites on dislocations, thus allowing supersaturation to build up past the aragonite solubility curve. Sr2+ precipitates as a Sr-rich nucleus with the aragonite structure which acts as a template for aragonite growth. The different morphology of gypsum speleothems can be explained by the

  16. Geology and preliminary dating of the hominid-bearing sedimentary fill of the Sima de los Huesos Chamber, Cueva Mayor of the Sierra de Atapuerca, Burgos, Spain.

    Science.gov (United States)

    Bischoff, J L; Fitzpatrick, J A; León, L; Arsuagà, J L; Falgueres, C; Bahain, J J; Bullen, T

    1997-01-01

    Sediments of the Sima de los Huesos vary greatly over distances of a few meters. This is typical of interior cave facies, and caused by cycles of cut and fill. Mud breccias containing human bones, grading upwards to mud containing bear bones, fill an irregular surface cut into basal marks and sands. The lack of Bedding and the chaotic abundance of fragile speleothem clasts in the fossiliferous muds suggests that the deposit was originally a subterranean pond facies, and that after emplacement of the human remains, underwent vigorous post-depositional rotation and collapse and brecciation, caused by underlying bedrock dissolution and undermining. The fossiliferous deposits are capped by flowstone and guano-bearing muds which lack large-mammal fossils. U-series and radiocarbon dating indicates the capping flowstones formed from about 68 ka to about 25 ka. U-series analyses of speleothem clasts among the human fossils indicate that all are at, or close to, isotopic equilibrium (> 350 ka). The distribution of U-series dates for 25 bear bones (154 +/- 66 ka) and for 16 human bones (148 +/- 34 ka) is similar and rather broad. Because the human bones seem to be stratigraphically older than chose of the bears, the results would indicate that most of the bones have been accumulating uranium irregularly with time. Electron spin resonance (ESR) analyses of six selected bear bones indicates dates of 189 +/- 28 ka, for which each is cordant with their corresponding U-series date (181 +/- 41 ka). Combined ESR and U-series dates for these samples yielded 200 +/- 4 ka. Such agreement is highly suggestive that uranium uptake in these bones was close to the early-uptake (EU) model, and the dates are essentially correct. Another three selected samples yielded combined ESR U-series dates of 320 +/- 4 ka with a modeled intermediate-mode of uranium uptake. The dating results, therefore, seem to provide a firm minimum age of about 200 ka for the human entry: and suggestive evidence of

  17. A continuous high-resolution record of western South Island environmental change over the last 31,000 years from stable isotope analyses of two north-west Nelson speleothems

    International Nuclear Information System (INIS)

    Hellstrom, J.; McCulloch, M.; Stone, J.

    1997-01-01

    Core samples were taken through large sheets of calcite flowstone growing in two cave systems, Nettlebed, and Exhaleair, in north-west Nelson, New Zealand. The sampled flowstones are at elevations of 400 m asl and 600 m asl, and are both located 200m below the surface. Ten high-precision U-series dates, measured by thermal ionisation mass spectroemtry, indicate the Nettlebed flowstone grew continuously over the last 31 ka. The Exhaleair flowstone grew continuously over the last 16 ka, following a 50 ka hiatus in deposition. The speleothems from both caves show similar records of oxygen isotope variation over the last 16 ka. The carbon isotope record from Nettlebed shows considerable variation, of almost 10 per thousand from the last glacial maximum to the early Holocene. It is anticipated that these well-dated speleothem records will enable more accurate constraints to be placed on the timing of glacial advances and vegetation changes in the western South Island than are possible using the available radiocarbon ages alone. (author)

  18. The earliest settlers of Mesoamerica date back to the late Pleistocene.

    Directory of Open Access Journals (Sweden)

    Wolfgang Stinnesbeck

    Full Text Available Preceramic human skeletal remains preserved in submerged caves near Tulum in the Mexican state of Quintana Roo, Mexico, reveal conflicting results regarding 14C dating. Here we use U-series techniques for dating a stalagmite overgrowing the pelvis of a human skeleton discovered in the submerged Chan Hol cave. The oldest closed system U/Th age comes from around 21 mm above the pelvis defining the terminus ante quem for the pelvis to 11311±370 y BP. However, the skeleton might be considerable older, probably as old as 13 ky BP as indicated by the speleothem stable isotope data. The Chan Hol individual confirms a late Pleistocene settling of Mesoamerica and represents one of the oldest human osteological remains in America.

  19. A Uranium-Lead Chronology of Speleothem Deposition in the Canadian Arctic

    Science.gov (United States)

    Gambino, C.; Shakun, J. D.; McGee, D.; Ramezani, J.; Khadivi, S.; Wong, C. I.

    2017-12-01

    The Artic is one of the fastest warming regions on the planet. Currently much of the Arctic is covered by permafrost, which contains approximately 1,700 gigatons of organic carbon. Permafrost thaw could release a substantial amount of this carbon as greenhouse gases into the atmosphere through microbial decomposition, potentially dramatically amplifying anthropogenic warming. However, the risk of permafrost thaw is uncertain, with models exhibiting a wide range of possibilities. Assessing the stability of permafrost during past interglacial periods enables evaluation of the sensitivity of permafrost to warming. Cave mineral deposits (speleothems) in areas currently covered with permafrost can act as a proxy for past permafrost thaw, as liquid water is one criteria of speleothem growth and thus implies thawed ground conditions. Previous uranium-thorium (U-Th) dating of speleothems (n=67) from a wide range of latitudes and permafrost zones across the southern Canadian Rockies, Northwest Territories, and the northern Yukon suggest deposition during Marine Isotope Stage (MIS) 11 and 13. The majority of U-Th dates of these speleothems, however, exceed the U-Th dating limit of 600 ka. In this study, we apply uranium-lead (U-Pb) geochronology to several of these speleothems to extend the records of speleothem growth further back in time. Initial results include a U-Pb age of 428 ± 14 ka that replicates a previous U-Th age of 416.8 ± 7.9 ka, and U-Pb ages on two other speleothems of 870 ± 100 ka and 1502 ± 30 ka. The results of currently in progress U-Pb analyses and a comparison of results with paleo-temperature and ice volume reconstructions will also be presented.

  20. Age of Zhoukoudian Homo erectus determined with (26)Al/(10)Be burial dating.

    Science.gov (United States)

    Shen, Guanjun; Gao, Xing; Gao, Bin; Granger, Darryl E

    2009-03-12

    The age of Zhoukoudian Homo erectus, commonly known as 'Peking Man', has long been pursued, but has remained problematic owing to the lack of suitable dating methods. Here we report cosmogenic (26)Al/(10)Be burial dating of quartz sediments and artefacts from the lower strata of Locality 1 in the southwestern suburb of Beijing, China, where early representatives of Zhoukoudian Homo erectus were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful age measurements, 0.77 +/- 0.08 million years (Myr, mean +/- s.e.m.), provides the best age estimate for lower cultural layers 7-10. Together with previously reported U-series dating of speleothem calcite and palaeomagnetic stratigraphy, as well as sedimentological considerations, these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages (MIS) 17-19, in the range of approximately 0.68 to 0.78 Myr ago. These ages are substantially older than previously supposed and may imply early hominin's presence at the site in northern China through a relatively mild glacial period corresponding to MIS 18.

  1. Timing of the onset of MIS 11 revealed by speleothem in southern Europe

    Science.gov (United States)

    Hu, Hsun-Ming; Shen, Chuan-Chou; Michel, Véronique; Kano, Akihiro

    2017-04-01

    The interglacial period, known as Marine Isotope Stage 11 (MIS 11, 428-397 thousand years ago), is often considered as a potential analogue for future climate projection because of the similar patterns of insolation variability. However, studies on mechanisms of the onset of MIS 11 (called Termination V, T-V) in response to insolation increase is still hampered by a lack of good dating materials in paleoclimate archives, despite a stack of East Asian monsoon records with precise U-Th dates has been proposed. Previous studies suggested the δ18O value registered in speleothems in Mediterranean realm can be a good bridge connecting the U-Th-based age model of speleothem to marine cores from Mediterranean sea, which opens a new possibility to detect ocean-atmosphere/internal-external forcing interaction beyond 14C dating limitation. Here we present a new speleothem δ18O record from northern Italy covering 500-300 thousand years ago. The results show a similar pattern with δ18O records of marine cores around Mediterranean. The age model of the speleothem hence provides an opportunity for tuning the marine cores, which could improve our understanding of relationship between global atmosphere and ocean circulations.

  2. Deuterium isotope composition of palaeoinfiltration water trapped in speleothems

    International Nuclear Information System (INIS)

    Rozanski, K.

    1987-05-01

    Analytical and methodological aspects of combined isotope investigations of carbonate cave deposits are thoroughly discussed in the report. Weight is put on isotope analyses of fluid inclusions (D and 18 O content) extracted from speleothems of known age. Dating was done by the 230 Th/ 234 U ratio method. Isotopic analyses of speleothems originating from European caves allowed some important conclusions to be formulated regarding past climatic and environmental conditions prevailing over the European continent during the last 300,000 yrs: a) δD values of fluid inclusions suggest a remarkable constancy of the heavy-isotope content of European palaeoinfiltration waters recharged during interglacial periods, b) a climate-induced, long-term changes in isotopic composition of precipitation and surface air temperature over Europe can be characterized by the deuterium gradient of ca.1 4 deg./oo/deg. C, c) an apparent constancy of the continental gradient in deuterium content of European palaeoinfiltration waters as judged from the fluid inclusion data suggests that atmospheric circulation over Europe did not undergo substantial changes for at least 300,000 years

  3. New ESR/U-series data for the early Middle Pleistocene site of Isernia la Pineta, Italy

    International Nuclear Information System (INIS)

    Shao Qingfeng; Bahain, Jean-Jacques; Falgueres, Christophe; Peretto, Carlo; Arzarello, Marta; Minelli, Antonella; Thun Hohenstein, Ursula; Dolo, Jean-Michel; Garcia, Tristan; Frank, Norbert; Douville, Eric

    2011-01-01

    Located in Southern Italy, the Early Palaeolithic site of Isernia la Pineta has provided numerous palaeontological remains and artefacts in well-defined fluvio-lacustrine sequence. The normal magnetization of the main archaeological layer t3a and 39 Ar/ 40 Ar date of 610 ± 10 (2σ) ka, obtained from the immediately overlaying geological level, put the Isernia assemblage in the first part of the Middle Pleistocene. Previous ESR/U-series analyses of Isernia fossil teeth have displayed both recent U-uptake and severe underestimation of the ESR/U-series dates in comparison with the 39 Ar/ 40 Ar age. In order to identify the cause of this age underestimation, new analyses were realized in the present study on four bovid teeth directly recovered from the archaeological surface t3a. The ESR/U-series dates obtained were once again strongly underestimated, with an error weighted mean age of 435 ± 24 (1σ) ka. These too young dates could be associated to a change of the environmental γ-dose rate during the geological history of the Isernia site, related to the revealed recent U-uptake into the palaeontological remains of the archaeological level. If we consider that this dose rate change was coeval with a wet interglacial period and taking the 39 Ar/ 40 Ar age as geochronological reference, simulations with two dose rate steps indicate that this change could be correlated with marine isotopic stage 7 (MIS 7).

  4. New ESR/U-series data for the early Middle Pleistocene site of Isernia la Pineta, Italy

    Energy Technology Data Exchange (ETDEWEB)

    Shao Qingfeng, E-mail: shao@mnhn.fr [Departement de Prehistoire du Museum National d' Histoire Naturelle, UMR 7194 CNRS, 1 rue Rene Panhard, F-75013 Paris (France); Bahain, Jean-Jacques; Falgueres, Christophe [Departement de Prehistoire du Museum National d' Histoire Naturelle, UMR 7194 CNRS, 1 rue Rene Panhard, F-75013 Paris (France); Peretto, Carlo; Arzarello, Marta; Minelli, Antonella; Thun Hohenstein, Ursula [Dipartimento di Biologia ed Evoluzione, Universita di Ferrara, C.so Ercole I d' Este 32, I-44121 Ferrara (Italy); Dolo, Jean-Michel; Garcia, Tristan [CEA, LIST, Laboratoire National Henri Becquerel, F-91191 Gif-sur-Yvette cedex (France); Frank, Norbert; Douville, Eric [Laboratoire des Sciences du Climat et de l' Environnement, LSCE/IPSL, UMR 8212 CNRS-CEA-UVSQ, Domaine du CNRS, F-91198 Gif/Yvette cedex (France)

    2011-09-15

    Located in Southern Italy, the Early Palaeolithic site of Isernia la Pineta has provided numerous palaeontological remains and artefacts in well-defined fluvio-lacustrine sequence. The normal magnetization of the main archaeological layer t3a and {sup 39}Ar/{sup 40}Ar date of 610 {+-} 10 (2{sigma}) ka, obtained from the immediately overlaying geological level, put the Isernia assemblage in the first part of the Middle Pleistocene. Previous ESR/U-series analyses of Isernia fossil teeth have displayed both recent U-uptake and severe underestimation of the ESR/U-series dates in comparison with the {sup 39}Ar/{sup 40}Ar age. In order to identify the cause of this age underestimation, new analyses were realized in the present study on four bovid teeth directly recovered from the archaeological surface t3a. The ESR/U-series dates obtained were once again strongly underestimated, with an error weighted mean age of 435 {+-} 24 (1{sigma}) ka. These too young dates could be associated to a change of the environmental {gamma}-dose rate during the geological history of the Isernia site, related to the revealed recent U-uptake into the palaeontological remains of the archaeological level. If we consider that this dose rate change was coeval with a wet interglacial period and taking the {sup 39}Ar/{sup 40}Ar age as geochronological reference, simulations with two dose rate steps indicate that this change could be correlated with marine isotopic stage 7 (MIS 7).

  5. Verification of the causes of glaciations and sea level changes using the records of calcite speleothems.

    Directory of Open Access Journals (Sweden)

    Shopov Yavor Y.

    2000-01-01

    Full Text Available The luminescence of calcite speleothems displays an exponential dependence on soil temperature unless there is a dense cover of forest over the cave to dampen it. This relationship is determined primarily by the strength of solar visible and infrared radiation. It is suggested that, as a consequence, the microzonal variations of luminescence often found in speleothems can be used as a proxy index of Solar Insolation. The luminescence solar insolation proxy record of a speleothem from Jewel Cave, South Dakota, USA, was found to display millenial and centennial cycles in the record. It exhibits a rapid increase in solar insolation at 139 ± 5.5 kyrs. This increase precedes that suggested by the Orbital theory by about 10,000 years and is due to superimposition of the most powerful cycle in solar luminosity of 11.5 kyrs, upon the curve of orbital variations. The record from a speleothem in Duhlata Cave, Bulgaria matches that of South Dakota within the limits of dating error, indicating that both of these records (which are 10,000 km apart measure global solar insolation controls rather than local paleotemperature variations.

  6. Speleothems as Examples of Chemical Equilibrium Processes.

    Science.gov (United States)

    Wilson, James R.

    1984-01-01

    The chemical formation of speleothems such as stalactites and stalagmites is poorly understood by introductory geology instructors and misrepresented in most textbooks. Although evaporation may be a controlling factor in some caves, it is necessary to consider chemical precipitation as more important in controlling the diagenesis of calcium…

  7. Advancements in the use of speleothems as climate archives

    Science.gov (United States)

    Wong, Corinne I.; Breecker, Daniel O.

    2015-11-01

    Speleothems have become a cornerstone of the approach to better understanding Earth's climatic teleconnections due to their precise absolute chronologies, their continuous or semicontinuous deposition and their global terrestrial distribution. We review the last decade of speleothem-related research, building off a similar review by McDermott (2004), in three themes - i) investigation of global teleconnections using speleothem-based climate reconstructions, ii) refinement of climate interpretations from speleothem proxies through cave monitoring, and iii) novel, technical methods of speleothem-based climate reconstructions. Speleothem records have enabled critical insight into the response of global hydroclimate to large climate changes. This includes the relevant forcings and sequence of climatic responses involved in glacial terminations and recognition of a global monsoon response to climate changes on orbital and millennial time scales. We review advancements in understanding of the processes that control speleothem δ13C values and introduce the idea of a direct atmospheric pCO2 influence. We discuss progress in understanding kinetic isotope fractionation, which, with further advances, may help quantify paleoclimate changes despite non-equilibrium formation of speleothems. This feeds into the potential of proxy system modeling to consider climatic, hydrological and biogeochemical processes with the objective of quantitatively interpreting speleothem proxies. Finally, we provide an overview of emerging speleothem proxies and novel approaches using existing proxies. Most recently, technical advancements made in the measurement of fluid inclusions are now yielding reliable determinations of paleotemperatures.

  8. Dansgaard-Oeschger events and their reflection in speleothems (Hans Oeschger Medal Lecture)

    Science.gov (United States)

    Bar-Matthews, Miryam

    2013-04-01

    Speleothems in karstic cave environments form by passage of meteoric water through the overlying soils, where the water dissolves CO2 to form carbonic acid, which in turn dissolves the host-rock carbonate. Degassing of the carbonate supersaturated meteoric water leads to the formation of calcite speleothems, which therefore can be considered as the end product in the much larger sea-atmosphere-land cycle. Their stable isotopic and geochemical composition reflect the environmental conditions above the cave, which in turn depend on larger scale parameters such as isotopic composition of the rainfall source, atmospheric storm patterns, ocean-land heat transfer. In this talk I specifically address the potential of using speleothems to look at short term climatic events: the Dansgaard-Oeschger (D-O) events; rapid climate changes first observed in Greenland ice cores by Hans Oeschger with Willi Dansgaard and suggested to occur during the last glacial period. Many researches now show that D-O events are globally synchronous and can be identified in the marine and terrestrial climate records. Given, the ability to accurately date speleothems and to perform high-resolution studies of stable isotopes, trace elements and various other proxies (e.g., fluid inclusions, 'clumped isotopes' thermometry), it has become clear that speleothems enable us to better date the exact timing of D-O events and to understand the climatic response on land in different parts of the world to their occurrence, i.e., to address specific questions on the marine-atmosphere interaction, sea surface temperature, rainfall generation and their influence on human habitation and dispersal. Since the stable isotopic signal in speleothems primarily is a function of temperature and isotopic composition of rainfall, short time climatic events can be registered in fast growing speleothems. Indeed recent studies clearly demonstrate that D-O events are registered in speleothems, for example, vegetation changes

  9. Analytical techniques for extracting Quaternary climate data from speleothems

    International Nuclear Information System (INIS)

    Whittaker, T.

    2007-01-01

    Speleothems are deposits formed in caves as a result of chemical precipitation from groundwater flowing over or dripping onto a surface. In most limestone caves the precipitated mineral is calcite, although aragonite forms are also common. Over time, and with continued chemical precipitation, each form 'grows' layer by layer. Therefore, similar to tree rings (although speleothem layers may not be annually resolved), speleothems provide an archive of information about past climate. In addition they may provide further information on vegetation changes, hydrology, sea level, water-rock interaction, landscape evolution, tectonics and human action. For palaeoclimate studies the three most useful speleothem forms are stalagmites, stalactites (including Straws) and flowstones. (author). 23 refs

  10. Age frequency distribution and revised stable isotope curves for New Zealand speleothems: palaeoclimatic implications

    Directory of Open Access Journals (Sweden)

    Williams Paul W.

    2010-07-01

    Full Text Available The occurrence of speleothems in New Zealand with reversed magnetism indicates that secondary calcite deposition in caves has occurred for more than 780 thousand years (ka. 394 uranium-series dates on 148 speleothems show that such deposition has taken place somewhere in the country with little interruption for more than 500 ka. A relative probability distribution of speleothem ages indicates that most growth occurred in mild, moist interglacial and interstadial intervals, a conclusion reinforced by comparing peaks and troughs in the distribution with time series curves of speleothem δ18O and δ13C values. The stable isotope time series were constructed using data from 15 speleothems from two different regions of the country. The greater the number of overlapping speleothem series (i.e. the greater the sample depth for any one region, the more confidence is justified in considering the stacked record to be representative of the region. Revising and extending earlier work, composite records are produced for central-west North Island (CWNI and north-west South Island (NWSI. Both demonstrate that over the last 15 ka the regions responded similarly to global climatic events, but that the North Island site was also influenced by the waxing and waning of regional subtropical marine influences that penetrated from the north but did not reach the higher latitudes of the South Island. Cooling marking the commencement of the last glacial maximum (LGM was evident from about 28 ka. There was a mid-LGM interstadial at 23-21.7 ka and Termination 1 occurred around 18.1 ka. The glacial-interglacial transition was marked by a series of negative excursions in δ18O that coincide with dated recessional moraines in South Island glaciers. A late glacial cooling event, the NZ Late Glacial Reversal, occurred from 13.4-11.2 ka and this was followed by an early Holocene optimum at 10.8 ka. Comparison of δ18O records from NWSI and EPICA DML ice-core shows climatic

  11. Atmospheric dust contribution to budget of U-series nuclides in weathering profiles. The Mount Cameroon volcano

    Science.gov (United States)

    Pelt, E.; Chabaux, F. J.; Innocent, C.; Ghaleb, B.

    2009-12-01

    , the dust contribution will not significantly influence U-series dating. Chabaux F., Bourdon B., Riotte J. (2008). U-series Geochemistry in weathering profiles, river waters and lakes. Radioactivity in the Environment, 13, 49-104. Dia A., Chauvel C., Bulourde M. and Gérard M. (2006). Eolian contribution to soils on Mount Cameroon: Isotopic and trace element records. Chem. Geol. 226, 232-252. Rydell H.S. and Prospero J.M. (1972). Uranium and thorium concentrations in wind-borne Saharan dust over the western equatorial north atlantic ocean. EPSL 14, 397-402.

  12. Calibrating the glycerol dialkyl glycerol tetraether temperature signalin speleothems

    NARCIS (Netherlands)

    Blyth, A.J.; Schouten, S.

    2013-01-01

    Palaeotemperature proxies based on glycerol dialkyl glycerol tetraethers (GDGTs) lipids have been established for marine and lacustrine environments, but there has been relatively little study of their application in speleothems. In this study we analyse the GDGT content of 33 speleothem samples

  13. Calibrating the glycerol dialkyl glycerol tetraether temperature signal in speleothems

    NARCIS (Netherlands)

    Blyth, A.J.; Schouten, S.|info:eu-repo/dai/nl/137124929

    2013-01-01

    Palaeotemperature proxies based on glycerol dialkyl glycerol tetraethers (GDGTs) lipids have been established for marine and lacustrine environments, but there has been relatively little study of their application in speleothems. In this study we analyse the GDGT content of 33 speleothem samples

  14. Subtropical Climate Variability since the Last Glacial Maximum from Speleothem Precipitation Reconstructions in Florida

    Science.gov (United States)

    Polk, J.; van Beynen, P.; DeLong, K. L.; Asmerom, Y.; Polyak, V. J.

    2017-12-01

    Teleconnections between the tropical-subtropical regions of the Americas since the Last Glacial Maximum (LGM), particularly the Mid- to Late-Holocene, and high-resolution proxy records refining climate variability over this period continue to receive increasing attention. Here, we present a high-resolution, precisely dated speleothem record spanning multiple periods of time since the LGM ( 30 ka) for the Florida peninsula. The data indicate that the amount effect plays a significant role in determining the isotopic signal of the speleothem calcite. Collectively, the records indicate distinct differences in climate in the region between the LGM, Mid-Holocene, and Late Holocene, including a progressive shift in ocean composition and precipitation isotopic values through the period, suggesting Florida's sensitivity to regional and global climatic shifts. Comparisons between speleothem δ18O values and Gulf of Mexico marine records reveal a strong connection between the Gulf region and the terrestrial subtropical climate in the Late Holocene, while the North Atlantic's influence is clear in the earlier portions of the record. Warmer sea surface temperatures correspond to enhanced evaporation, leading to more intense atmospheric convection in Florida, and thereby modulating the isotopic composition of rainfall above the cave. These regional signals in climate extend from the subtropics to the tropics, with a clear covariance between the speleothem signal and other proxy records from around the region, as well as global agreement during the LGM period with other records. These latter connections appear to be driven by changes in the mean position of the Intertropical Convergence Zone and time series analysis of the δ18O values reveals significant multidecadal periodicities in the record, which are evidenced by agreement with the AMV and other multidecadal influences (NAO and PDO) likely having varying influence throughout the period of record. The climate variability

  15. Speleothem records of western Mediterranean. Hydrological variability along the Last Interglacial Period and marine linkages

    Science.gov (United States)

    Torner, Judit; Cacho, Isabel; Moreno, Ana; Stoll, Heather; Belmonte, Anchel; Sierro, Francisco J.; Frigola, Jaime; Martrat, Belen; Fornós, Joan; Arnau Fernández, Pedro; Hellstrom, John; Cheng, Hai; Edwards, R. Lawrence

    2016-04-01

    This study aims to identify and characterize regional hydrological variability in the western Mediterranean region in base to different geochemical parameters (δ18O, δ13C, and Mg/Ca ratios). Speleothems have been recovered from several caves located in southern central Pyrenees one and the others form the Balearic Islands. Their chronologies have been constructed in base on U/Th absolute dating and indicate that the speleothem sequences cover the end of the last interglacial and the glacial inception. One of the most remarkable features of the records is the intense and abrupt shift toward more arid conditions that marks the end of the last interglacial (MIS 5e). Furthermore, our speleothem records also show relatively humid but highly variable hydrological conditions during the interstadial periods from MIS 5c to 5a. These speleothem records have been compared with new generated western Mediterranean marine records from the Balearic Sea (MD99-2343) and Alboran Sea (OPD-977). Marine records include (1) proxies of sea surface temperature and changes in evaporation-precipitation rates based on pair analysis of δ18O and the Mg/Ca ratios in planktonic foraminifera Globigerina bulloides; (2) proxies of deep-water currents associated with the Western Mediterranean Deep Water (WMDW) based on grain size analyses. The results reveal that arid conditions on land were coeval with cold sea surface sub-stages (MIS 5b and 5d), and also with increases in the intensity of the WMDW-related currents. By contrast, humid and hydrological unstable atmosphere conditions were synchronous with sea surface warm sub-stages, and lower WMDW-related currents intensities (MIS 5a, c and e). Consequently, our results highly evidence a strong atmospheric-oceanic coupling, involving parallel changes in both surface but also deep western Mediterranean Sea conditions during the last interglacial period and the glacial inception.

  16. Preliminary U-series disequilibrium and thermoluminescence ages of surficial deposits and paleosols associated with Quaternary fault, Eastern Yucca Mountain

    International Nuclear Information System (INIS)

    Paces, J.B.; Menges, C.M.; Bush, C.A.; Futa, K.; Millard, H.T.; Maat, P.B.; Whitney, J.W.; Widmann, B.; Wesling, J.R.

    1994-01-01

    Geochronological control is an essential component of paleoseismic evaluation of faults in the Yucca Mountain region. New U-series disequilibrium and thermoluminescence age estimates for pedogenic deposits that bracket surface-rupture events are presented from four sites exposing the Paintbrush Canyon, Bow Ridge and Stagecoach Road faults. Ages show an internal consistency with stratigraphic relationships as well as an overall concordancy between the two independent geochronometers. Age estimates are therefore interpreted to date depositional events or episodes of pedogenic carbonate mobility that can be used to establish a paleoseismic fault chronology. Ultimately, this type of chronological information will be used to evaluate seismic hazards at Yucca Mountain

  17. Pleistocene speleothem fracturing in the foreland of the Western Carpathians: a case study from the seismically active eastern margin of the Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Bábek, O.; Briestenský, Miloš; Přecechtělová, G.; Štěpančíková, Petra; Hellstrom, J.C.; Drysdale, R.N.

    2015-01-01

    Roč. 59, č. 3 (2015), s. 491-506 ISSN 1641-7291 R&D Projects: GA ČR GAP210/12/0573 Institutional support: RVO:67985891 Keywords : speleothems * U/Th series dating * palaeoseismicity * Pleistocene * Bohemian Massif Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.858, year: 2015

  18. Belgian speleothems from the Last Interglacial: insights in the onset of glacial conditions in north western Europe.

    Science.gov (United States)

    Vansteenberge, Stef; Verheyden, Sophie; Cheng, Hai; Edwards, Lawrence R.; Keppens, Eddy; Claeys, Philippe

    2015-04-01

    Currently, a dataset combining at least four speleothems from two different cave systems in southern Belgium (Han-sur-Lesse and Remouchamps) is being constructed to improve the understanding of the termination of the Eemian and the millennial to decadal variability of the Early Glacial times in north western Europe. Here, one of those speleothems is presented. The Han-stm-9 (or 'Triptyque') speleothem is a broken, 68 cm long and candle-shaped stalagmite from the Han-sur-Lesse cave system. The stalagmite was collected in summer 2013 within the southern part of the cave network and was dated between ~126 and ~99ka. Most likely, climate optimum conditions during the 130-125ka interval are linked to the growth of this and other speleothems from Belgian caves. This particular speleothem gained interest because of the partial conformity with the continental interglacial period in northern western Europe (130 - 118ka) and its dense calcite composition with visible layering, excluding post-depositional deformation. Furthermore, the stalagmite displays a complex growth history, with large variations in growth rates (ranging from and periods of ceased speleothem formation. Two hiatuses, with a distinct macroscopic expression, occur. The first one starts at 118.4ka and lasts until 113.0ka. A second hiatus is situated between ~108ka and 103.7ka. A trend in growth rate, consisting of slow growth gradually increasing towards very fast speleothem formation before both hiatuses, is observed. These intervals with very high growth rates, for instance around 118ka, enable high-resolution climate reconstructions via stable isotopes (δ18O and δ13C) and trace elements (Mg, Sr, Ba and P), down to centennial and decadal scale. The timing of the first hiatus corresponds with Greenland Stadial 26 and with the generally accepted termination of the Eemian in northern Europe at 119-118ka. Also, preliminary stable isotope studies have indicated a large detoriation of δ13C occurring right

  19. Reconstructing Past Climate Using Speleothems from Cueva de las Perlas, Northern Spain.

    Science.gov (United States)

    Deeprose, Laura; Wynn, Peter; Barker, Philip; Leng, Melanie; Noble, Stephen; Sahy, Diana

    2017-04-01

    Abrupt and severe oscillations in climate, termed Heinrich events, are documented in North Atlantic Ocean sediments between 85,000 - 30,000 years ago [1]. This time period also encapsulates the Neanderthal demise, a key transition in human evolution which is proposed to be driven at least in part by changing climate. The Iberian Peninsula represents the last known refuge of the Neanderthals. However, due to a scarcity of palaeoclimate archives from Iberia during this time period, the expression of these cooling events in the terrestrial realm remains poorly understood. As the extinction of the Neanderthal population seems to broadly coincide with the timing of Heinrich event 4, it is therefore critical to understand the terrestrial expression of these changes in ocean circulation. Speleothems from Cueva de las Perlas, northern Spain are being used to reconstruct past climatic and environmental change spanning this period of Neanderthal demise. U-Th dating has identified three suitable speleothems, allowing a precise chronology to be established. Through contemporary monitoring, the oxygen isotope composition of speleothem carbonate has been interpreted to carry a primary environmental signal of rainfall amount. The oxygen isotope values indicate a drying climate across the period of the Neanderthal population demise. Additionally, the carbon isotope record, interpreted to represent shifts in vegetation dynamics, indicates an overall drying during the studied time period. A high degree of climatic instability is superimposed on the overall drying trend, suggesting the prevailing climatic conditions could have been adding environmental pressure to an already marginalised hominin population. Further U-Th dating and high-resolution stable isotope analysis aims to constrain the magnitude and timing of these events. [1] Bond, G., Broecker, W., Johnsen, S.J., McManus, J., Labeyrie, L., Jouzel, J., Bonani, G., 1993. Correlations between North Atlantic sediments and

  20. The speleothem record from Sicily, an important palaeoclimate testimony in the heart of the Mediterranean: overview of current research

    Science.gov (United States)

    Deininger, Michael; Vattano, Marco; McDermott, Frank; Frisia, Silvia; Borsato, Andrea; Frank, Norbert; Spötl, Christoph; Scholz, Denis; Di Maggio, Cipriano; Madonia, Giuliana

    2017-04-01

    Sicily is located in the heart of the Mediterranean and takes a strategic position between the western and eastern Mediterranean as well as between northern Africa and continental Europe. It is a place of a diverse and great cultural heritage that goes back many thousands of years; it had been colonised by Phoenicians, Carthaginians, Greeks and Romans in Ancient times and served as a trading post and granary - the latter particularly for the Romans. Climate change scenarios studies suggest that Mediterranean ecosystems could change into deserts as a consequence of shifting temperature and precipitation patterns unparalleled in the Holocene period (Guiot and Cramer, 2016). It is, therefore, essential to shed light on past precipitation changes to gain knowledge on the timing, dynamics and causes of these changes by making use of natural environmental archives (such as speleothems). This information is not only important for palaeoclimate data-model comparisons but can also give archaeologists a wealth of information when studying cultural transformations. Speleothems are valuable natural archives of past climatic and environmental conditions on the continents. Major strengths include their suitability for accurate U-series age determinations and their preservation of multiple quasi-independent climate proxies - that can be linked to precipitation changes. Hence, speleothems proxy time series from the Mediterranean can be regarded as an important testimony of past environmental and climate changes (including precipitation) that allow to provide answers to the aforementioned questions. Here we present first result of ongoing speleothem research on Sicily, with focuses on Pietrazzi cave (Grotta dei Pietrazzi) located west of Palermo. It developed in limestone (limestone consisting of bioclastic packstone/wackestones, fore reef coral rudstones (calcirudite) and calcarenites.) of the Calcare di Piano Battaglia Formation. Pietrazzi cave is more than 600 m in length and

  1. Speleothem records of changes in the South American Summer Monsoon during MIS stages 5 and 6

    Science.gov (United States)

    Burns, S. J.; Kanner, L.; Cheng, H.; Edwards, R.

    2011-12-01

    Little information exists about the behavior of the South American Summer Monsoon prior to the Last Glacial Period. Speleothems from the Peruvian Altiplano are one possible archive of SASM intensity because oxygen isotopes of rainfall on the Altiplano are primarily controlled by the intensity of rainfall in upstream moisture source region, the Amazon Basin. Here, we present results from a two speleothems collected from Gruta de Huagapo, a cave in the central Peruvian Altiplano (12°S, 76°W, ~3800m elevation). The samples grew from approximately 115-125 ky BP and from 136-168 ky BP, spanning time periods equivalent to much of MIS stage 5e and the transition into MIS 5d and MIS 6. Chronologies were determined by U-Th dating techniques and the dates are in stratigraphic with analytical errors Titicaca (Fritz et al, 2007). At present we have isotopic data from only the youngest 10 ky of the older sample. The values are generally more depleted, with most between -16% and -17%, suggesting an intensified SASM during MIS 6 as compared to 5e. A rapid increase in δ18O occurs at ~136 ky BP. Overall the trends in the data parallel major changes in δD from EPICA, but appear to lead the Antarctic time series by ~2 ky.

  2. Temperature reconstruction from dripwater hydrochemistry, speleothem fabric and speleothem δ13C: towards an integrated approach in temperate climate caves

    Science.gov (United States)

    Borsato, Andrea; Frisia, Silvia; Johnston, Vanessa; Spötl, Christoph

    2017-04-01

    Accurate reconstruction of past climate records from speleothem minerals requires a thorough understanding of both environmental and hydrologic conditions underpinning their formation. These conditions likely influenced how speleothems incorporate chemical signals that are used as climate proxies. Thus, a thorough investigation of environmental and hydrologic parameters is a pre-requisite to gain robust palaeoclimate reconstructions from stalagmites. Here, we present a systematic study of soil, dripwater and speleothems in temperate climate caves at different altitudes, which allowed the assessment of how mean annual air temperature in the infiltration area (MATinf) influences vegetation cover, soil pCO2 and, eventually, pCO2 of karst water and cave air. Our study demonstrates that for caves developed in pure carbonate rocks, the soil and aquifer pCO2 are directly related to the MATinf (Borsato et al., 2015). It is well known that soil and aquifer pCO2 control carbonate dissolution and the carbonate-carbonic acid system. By establishing a relationship between dripwater pCO2 and MATinf, we show that dripwater Ca content and calcite saturation state SIcc) are correlated with MATinf when unaffected by Prior Calcite Precipitation. In particular, dripwater saturation (SIcc = 0) is reached at a MATinf of 4.4°C in our study area. This MATinf delineates a ''speleothem limit", above which speleothems composed of sparitic calcite should not form (Borsato et al., 2016). In fact, sparitic calcite speleothems do not form, today, in caves with a MATinf well as calcite δ13C in speleothems that were not significantly influenced by kinetic fractionation. A linear correlation between calcite δ13C and MATinf was obtained for modern sparitic speleothems that formed at isotopic equilibrium (Johnston et al., 2013). The combination of these two approaches (present-day dripwater SIcc and calcite δ13C in sparitic speleothems) can be used to reconstruct the past MATinf for high

  3. Combined ESR/U-series chronology of Acheulian hominid-bearing layers at Trinchera Galeria site, Atapuerca, Spain

    International Nuclear Information System (INIS)

    Falgueres, Christophe; Bahain, Jean-Jacques; Shao, Qingfeng; Bischoff, James L.; Perez-Gonzalez, Alfredo; Ortega, Ana Isabel; Bermudez de Castro, Jose Maria; Olle, Andreu; Vallverdu, Josep; Quiles, Anita; Ghaleb, Bassam; Moreno, Davinia; Dolo, Jean-Michel; Vallverdu, Josep; Carbonell, Eudald; Arsuaga, Juan Luis

    2013-01-01

    The Sierra de Atapuerca, northern Spain, is known from many prehistoric and paleontologic sites documenting human prehistory in Europe. Three major sites, Gran Dolina, Galeria and Sima del Elefante, range in age from the oldest hominin of Western Europe dated to 1.1 to 1.3 Ma (millions of years ago) at Sima del Elefante to c.a. 0.2 Ma on the top of the Galeria archaeological sequence. Recently, a chronology based on luminescence methods (Thermoluminescence [TL] and Infrared Stimulated Luminescence [IRSL]) applied to cave sediments was published for the Gran Dolina and Galeria sites. The authors proposed for Galeria an age of 450 ka (thousands of years ago) for the units lower GIII and GII, suggesting that the human occupation there is younger than the hominid remains of Sima de los Huesos (≥530 ka) around 1 km away. In this paper, we present new results obtained by combined Electron Spin Resonance/Uranium-series (ESR/U-series) dating on 20 herbivorous teeth from different levels at the Galeria site. They are in agreement with the TL results for the upper part of the stratigraphic sequence (GIV and GIIIb), in the range of between 200 and 250 ka. But for the GIIIa to GIIb levels, the TL ages become abruptly older by 200 ka while ESR ages remain relatively constant. Finally, the TL and ESR data agree in the lowest part of the section (GIIa); both fall in the range of around 350-450 ka. Our results suggest a different interpretation for the GII, GIII and GIV units of Galeria and the upper part of Gran Dolina (TD10 and TD11) than obtained by TL. The ESR/U-series results are supported by a Bayesian analysis, which allows a better integration between stratigraphic information and radiometric data. (authors)

  4. A Two-year Record of Daily Rainfall Isotopes from Fiji: Implications for Reconstructing Precipitation from Speleothem δ18O

    Science.gov (United States)

    Brett, M.; Mattey, D.; Stephens, M.

    2015-12-01

    Oxygen isotopes in speleothem provide opportunities to construct precisely dated records of palaeoclimate variability, underpinned by an understanding of both the regional climate and local controls on isotopes in rainfall and groundwater. For tropical islands, a potential means to reconstruct past rainfall variability is to exploit the generally high correlation between rainfall amount and δ18O: the 'amount effect'. The GNIP program provides δ18O data at monthly resolution for several tropical Pacific islands but there are few data for precipitation isotopes at daily resolution, for investigating the amount effect over different timescales in a tropical maritime setting. Timescales are important since meteoric water feeding a speleothem has undergone storage and mixing in the aquifer system and understanding how the isotope amount effect is preserved in aquifer recharge has fundamental implications on the interpretation of speleothem δ18O in terms of palaeo-precipitation. The islands of Fiji host speleothem caves. Seasonal precipitation is related to the movement of the South Pacific Convergence Zone, and interannual variations in rainfall are coupled to ENSO behaviour. Individual rainfall events are stratiform or convective, with proximal moisture sources. We have daily resolution isotope data for rainfall collected at the University of the South Pacific in Suva, covering every rain event in 2012 and 2013. δ18O varies between -18‰ and +3‰ with the annual weighted averages at -7.6‰ and -6.8‰ respectively, while total recorded rainfall amount is similar in both years. We shall present analysis of our data compared with GNIP, meteorological data and back trajectory analyses to demonstrate the nature of the relationship between rainfall amount and isotopic signatures over this short timescale. Comparison with GNIP data for 2012-13 will shed light on the origin of the amount effect at monthly and seasonal timescales in convective, maritime, tropical

  5. Alchemy in the underworld - recent progress and future potential of organic geochemistry applied to speleothems.

    Science.gov (United States)

    Blyth, Alison

    2016-04-01

    Speleothems are well used archives for chemical records of terrestrial environmental change, and the integration of records from a range of isotopic, inorganic, and organic geochemical techniques offers significant power in reconstructing both changes in past climates and identifying the resultant response in the overlying terrestrial ecosystems. The use of organic geochemistry in this field offers the opportunity to recover new records of vegetation change (via biomarkers and compound specific isotopes), temperature change (via analysis of glycerol dialkyl glycerol tetraethers, a compound group derived from microbes and varying in structure in response to temperature and pH), and changes in soil microbial behaviour (via combined carbon isotope analysis). However, to date the use of organic geochemical techniques has been relatively limited, due to issues relating to sample size, concerns about contamination, and unanswered questions about the origins of the preserved organic matter and rates of transport. Here I will briefly review recent progress in the field, and present a framework for the future research needed to establish organic geochemical analysis in speleothems as a robust palaeo-proxy approach.

  6. Interrogating trees for isotopic archives of atmospheric sulphur deposition and comparison to speleothem records

    International Nuclear Information System (INIS)

    Wynn, P.M.; Loader, N.J.; Fairchild, I.J.

    2014-01-01

    Palaeorecords which depict changes in sulphur dynamics form an invaluable resource for recording atmospheric pollution. Tree rings constitute an archive that are ubiquitously available and can be absolutely dated, providing the potential to explore local- to regional-scale trends in sulphur availability. Rapid isotopic analysis by a novel “on-line” method using elemental analyser isotope ratio mass spectrometry (EA-IRMS) is developed, achieving sample precision of <0.4‰ using sample sizes of 40 mg wood powder. Tree cores from NE Italy show trends in pollution, evidenced through increasing concentrations of sulphur towards the youngest growth, and inverse trends in sulphur isotopes differentiating modern growth with light sulphur isotopes (+0.7‰) from pre-industrial growth (+7.5‰) influenced by bedrock composition. Comparison with speleothem records from the same location demonstrate replication, albeit offset in isotopic value due to groundwater storage. Using EA-IRMS, tree ring archives form a valuable resource for understanding local- to regional-scale sulphur pollution dynamics. - Highlights: • Sulphur isotopes from tree rings are analysed using ‘on-line’ EA combustion. • Isotopes differentiate modern growth influenced by pollution from pre-industrial growth. • Biogeochemical cycling imparts minimal delay in sulphur incorporation into tree rings. • Trends in pollution are replicated between speleothems and trees from the same location. - Sulphur isotopes extracted from tree ring records are used to identify twentieth century pollution dynamics at the local- to regional-scale

  7. Carbon and oxygen stable isotope and trace element studies in speleothems and across the J-K boundary, Central Italy

    International Nuclear Information System (INIS)

    Kudielka, G.

    2001-07-01

    Carbon and Oxygen stable isotope ratios of carbonates decisively depend on fractionation during physicochemical processes. Therefore, they represent a powerful tool to derive information on past conditions under which the carbonates formed. Isotope ratio mass spectrometry (IRMS) offers a large range of applications. This thesis presents two projects based upon investigation of carbon and oxygen stable isotope ratios combined with trace element abundances (determined by instrumental neutron activation analysis, INAA) in carbonates. (1) Palaeoclimatic investigation on speleothems from central Italy. Four speleothems from Grotta Grande del Vento, central Italy, were analyzed for stable isotope ratios and trace element abundances, and age dated to obtain a chronologically reliable stable isotope profile. The speleothems were sampled by means of a dental drill to gain a stable isotope profile with a 0.5 mm resolution, trace element abundances have been performed by INAA every 0.5 cm, and the samples for age dating were picked according to remarkable features in the stable isotope trends and analyzed by TIMS. The record covers the period from 93 ka until the early holocene with a hiatus lasting from 75 ka until 65.0 ka. Speleothem growth during the last glacial indicates moderate conditions in the Frasassi region back then. Comparison with speleothems from Ireland, France and northern Italy reveal a north-south slope in d18O, indicating, that the rain over central Italy mainly originates from the North Atlantic. Depletion of moisture in d18O during its continental trajectory is due to rainout, which primarily extracts the heavy isotopes. The stable isotope record is in good agreement with the high-resolution speleothem record from Soreq Cave, Israel. Distinct isotopic events coincide between 85 ka and 80 ka, between ∼ 60 ka and 50 ka and from the last glacial to the early holocene. An offset has been existing between the two records at any time. The speleothems of

  8. Tropical Indo-Pacific hydroclimate response to North Atlantic forcing during the last deglaciation as recorded by a speleothem from Sumatra, Indonesia

    Science.gov (United States)

    Wurtzel, Jennifer B.; Abram, Nerilie J.; Lewis, Sophie C.; Bajo, Petra; Hellstrom, John C.; Troitzsch, Ulrike; Heslop, David

    2018-06-01

    Abrupt changes in Atlantic Meridional Overturning Circulation are known to have affected the strength of the Indian and Asian Monsoons during glacial and deglacial climate states. However, there is still much uncertainty around the hydroclimate response of the Indo-Pacific Warm Pool (IPWP) region to abrupt climate changes in the North Atlantic. Many studies suggest a mean southward shift in the intertropical convergence zone (ITCZ) in the IPWP region during phases of reduced Atlantic meridional overturning, however, existing proxies have seasonal biases and conflicting responses, making it difficult to determine the true extent of North Atlantic forcing in this climatically important region. Here we present a precisely-dated, high-resolution record of eastern Indian Ocean hydroclimate variability spanning the last 16 ky (thousand years) from δ18O measurements in an aragonite-calcite speleothem from central Sumatra. This represents the western-most speleothem record from the IPWP region. Precipitation arrives year-round at this site, with the majority sourced from the local tropical eastern Indian Ocean and two additional long-range seasonal sources associated with the boreal and austral summer monsoons. The Sumatran speleothem demonstrates a clear deglacial structure that includes 18O enrichment during the Younger Dryas and 18O depletion during the Bølling-Allerød, similar to the pattern seen in speleothems of the Asian and Indian monsoon realms. The speleothem δ18O changes at this site are best explained by changes in rainfall amount and changes in the contributions from different moisture pathways. Reduced rainfall in Sumatra during the Younger Dryas is most likely driven by reductions in moisture transport along the northern or southern monsoon transport pathways to Sumatra. Considered with other regional proxies, the record from Sumatra suggests the response of the IPWP to North Atlantic freshwater forcing is not solely driven by southward shifts of the

  9. ESR dating of marine fossil shells

    International Nuclear Information System (INIS)

    Radtke, U.; Mangini, A.; Gruen, R.

    1985-01-01

    In order to establish the relatively new ESR dating method for marine shells a detailed comparison with the independent U-series technique was carried out. Agreement of both dating methods with the geological classification is strongly dependent on the species investigated and environmental conditions. Several problems encountered in the determination of the accumulated dose as well as the annual dose are discussed. (author)

  10. ESR dating of marine fossil shells

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, U; Mangini, A; Gruen, R

    1985-01-01

    In order to establish the relatively new ESR dating method for marine shells a detailed comparison with the independent U-series technique was carried out. Agreement of both dating methods with the geological classification is strongly dependent on the species investigated and environmental conditions. Several problems encountered in the determination of the accumulated dose as well as the annual dose are discussed.

  11. Stable isotopes in speleothems as proxies of past environmental changes in the Alps

    International Nuclear Information System (INIS)

    Spoetl, C.; Burns, S.J.; Mangini, A.

    2002-01-01

    This short communication presents preliminary results and interpretations from an ongoing research project in the Obir Cave of southeast Austria. This cave system hosts abundant calcite dripstones many of which are actively forming today. The stable isotopic composition of a Holocene stalagmite dated by U-series TIMS techniques shows rather stable values throughout most of the last eight millennia, except for the last few hundred years when both C and O isotope values strongly increase (probably due to changes in the cave air circulation as a result of mining activity). (author)

  12. Speleothem and biofilm formation in a granite/dolerite cave, Northern Sweden

    DEFF Research Database (Denmark)

    Sallstedt, T.; Ivarsson, M.; Lundberg, J.

    2014-01-01

    incorporated remains of microorganisms. Two types of microbial communities can be distinguished associated with the speleothems: an Actinobacteria-like biofilm and a fungal community. Actinobacteria seem to play an important role in the formation of speleothem while the fungal community acts as both...... a constructive and a destructive agent. A modern biofilm dominated by Actinobacteria is present in the speleothem-free parts of the dolerite and located in cave ceiling cracks. These biofilms may represent sites of early speleothem formation. Because of its unusual position in between two types of host rock...

  13. High resolution analysis of uranium and thorium concentration as well as U-series isotope distributions in a Neanderthal tooth from Payre (Ardèche, France) using laser ablation ICP-MS

    Science.gov (United States)

    Grün, Rainer; Aubert, Maxime; Joannes-Boyau, Renaud; Moncel, Marie-Hélène

    2008-11-01

    We have mapped U ( 238U) and Th ( 232Th) elemental concentrations as well as U-series isotope distributions in a Neanderthal tooth from the Middle Palaeolithic site of Payre using laser ablation ICP-MS. The U-concentrations in an enamel section varied between 1 and 1500 ppb. The U-concentration maps show that U-migration through the external enamel surface is minute, the bulk of the uranium having migrated internally via the dentine into the enamel. The uranium migration and uptake is critically dependent on the mineralogical structure of the enamel. Increased U-concentrations are observed along lineaments, some of which are associated with cracks, and others may be related to intra-prismatic zones or structural weaknesses reaching from the dentine into the enamel. The uranium concentrations in the dentine vary between about 25,000 and 45,000 ppb. Our systematic mapping of U-concentration and U-series isotopes provides insight into the time domain of U-accumulation. Most of the uranium was accumulated in an early stage of burial, with some much later overprints. None of the uranium concentration and U-series profiles across the root of the tooth complied with a single stage diffusion-adsorption (D-A) model that is used for quality control in U-series dating of bones and teeth. Nevertheless, in the domains that yielded the oldest apparent U-series age estimates, U-leaching could be excluded. This means that the oldest apparent U-series ages of around 200 ka represent a minimum age for this Neanderthal specimen. This is in good agreement with independent age assessments (200-230 ka) for the archaeological layer, in which it was found. The Th elemental concentrations in the dental tissues were generally low (between about 1 and 20 ppb), and show little relationship with the nature of the tissue.

  14. Determination of dynamic Young’s modulus of vulnerable speleothems

    Czech Academy of Sciences Publication Activity Database

    Konečný, Pavel; Lednická, Markéta; Souček, Kamil; Staš, Lubomír; Kubina, Lukáš; Gribovszki, K.

    2015-01-01

    Roč. 20, č. 2 (2015), s. 156-163 ISSN 1335-1788 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : dynamic Young´s modulus * speleothem * bulk density * X-Ray Computed Tomography Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.390, year: 2015 http://actamont.tuke.sk/pdf/2015/n2/10Konecny.pdf

  15. Sails: a new gypsum speleothem from Naica, Chihuahua, Mexico

    Directory of Open Access Journals (Sweden)

    Forti Paolo

    2007-01-01

    Full Text Available The caves of Naica (Chihuahua, Mexico are perhaps the most famous mine caves of the world due to the presence of giganticgypsum crystals. Nevertheless, very little research has been carried out on this karst area until now. A multidisciplinary investigationstarted in 2006 with the aim not only to define the genesis and the age of the Naica gypsum crystals, but also on other scientificaspects of these caves.This paper describes a completely new type of gypsum speleothem: the “sails”, observed only inside the Cueva de las Velas, one ofthe caves of the Naica system. This speleothem consists of extremely thin, elongated skeleton crystals that have grown epitaxiallyonly on the tips of the gypsum crystals pointing upward. The genesis of sails is strictly related to the environmental conditions setup inside the cave just after the artificial lowering of the groundwater by mine dewatering (less than 20 yr ago. In a few years sail speleothems will disappear entirely and therefore this study is fundamental to preserve at least the memory of them.

  16. ESR/U-series chronology of the Lower Palaeolithic palaeo-anthropological site of Visogliano, Trieste, Italy

    International Nuclear Information System (INIS)

    Falgueres, C.; Bahain, J.J.; Yokoyama, Y.; Tozzi, C.; Boschian, G.; Dolo, J.M.; Mercier, N.; Valladas, H.

    2008-01-01

    The Visogliano shelter, in north-eastern Italy, is an important Middle Pleistocene occupation site where human remains were found together with an archaic lithic industry, including choppers, chopping tools and a few proto-bifaces. It is of utmost importance to try to document this period, when a second wave of settlement colonised Western Europe, carrying new flaking techniques and tools. Combined ESR/U-series analyses, integrated with bio-stratigraphical and environmental data, define a chronological frame for the layers from which the artefacts were unearthed. The lower levels, including human remains, can be dated to the 350-500 kyr time span, in agreement with micro-mammal and stratigraphical studies. These data make Visogliano one of the oldest palaeo-anthropological sites in Italy, where human remains are directly associated with proto-bifaces, choppers and chopping tools. In Western Europe, Visogliano is contemporaneous to the G soil of the Arago Cave, France, with which it shares several similarities in faunal assemblages and radiometric data, and which contains human remains also. These data make Visogliano as one of the oldest sites in Europe where the Acheulian culture is observed. (authors)

  17. Radioactive equilibria and disequilibria of U-series nuclides in erupting magmas from Izu arc volcanoes

    International Nuclear Information System (INIS)

    Sato, Jun; Kurihara, Yuichi; Takahashi, Masaomi

    2009-01-01

    Radioactive disequilibria among U-series nuclides are observed in the magmas from volcanoes in the world. Basaltic products from Izu arc volcanoes, including Izu-Oshima and Fuji volcanoes, show 230 Th 238 U and 226 Ra> 230 Th disequilibria, indicating that the addition of U-and Ra-rich fluid from the subducting slab to the mantle wedge at the magma genesis. The disequilibria of 226 Ra> 230 Th in the erupting magmas suggest that the timescale from magma genesis to the eruption may be less than 8000 years. (author)

  18. Metagenomic Analysis from the Interior of a Speleothem in Tjuv-Ante's Cave, Northern Sweden.

    Directory of Open Access Journals (Sweden)

    Marie Lisandra Zepeda Mendoza

    Full Text Available Speleothems are secondary mineral deposits normally formed by water supersaturated with calcium carbonate percolating into underground caves, and are often associated with low-nutrient and mostly non-phototrophic conditions. Tjuv-Ante's cave is a shallow-depth cave formed by the action of waves, with granite and dolerite as major components, and opal-A and calcite as part of the speleothems, making it a rare kind of cave. We generated two DNA shotgun sequencing metagenomic datasets from the interior of a speleothem from Tjuv-Ante's cave representing areas of old and relatively recent speleothem formation. We used these datasets to perform i an evaluation of the use of these speleothems as past biodiversity archives, ii functional and taxonomic profiling of the speleothem's different formation periods, and iii taxonomic comparison of the metagenomic results to previous microscopic analyses from a nearby speleothem of the same cave. Our analyses confirm the abundance of Actinobacteria and fungi as previously reported by microscopic analyses on this cave, however we also discovered a larger biodiversity. Interestingly, we identified photosynthetic genes, as well as genes related to iron and sulphur metabolism, suggesting the presence of chemoautotrophs. Furthermore, we identified taxa and functions related to biomineralization. However, we could not confidently establish the use of this type of speleothems as biological paleoarchives due to the potential leaching from the outside of the cave and the DNA damage that we propose has been caused by the fungal chemical etching.

  19. TL and EPR dating: some applications

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, S. [Institute of Physics, University of Sao Paulo, Sao Paulo (Brazil)

    2006-07-01

    The intensity of thermoluminescence light emitted by a crystal is a function of radiation dose. The number of defects or of radicals in a crystal or organic substances is also a function of radiation dose. Since such defects or radicals present EPR signals, the EPR intensity is also a function of radiation dose. These facts are basis for radiation dosimetry and can be applied in dating of archaeological potteries or other materials, as well as in dating geological substances such as sediments, caves speleothemes, animal teeth and bones. Recent investigation on sensitized quartz based dosimeters and dating calcite covering ancient wall painting to find early settlers in Brazil will be presented. (Author)

  20. The chronology of hand stencils in European Palaeolithic rock art: implications of new U-series results from El Castillo Cave (Cantabria, Spain).

    Science.gov (United States)

    García-Diez, Marcos; Garrido, Daniel; Hoffmann, Dirk; Pettitt, Paul; Pike, Alistair; Zilhão, Joao

    2015-07-20

    The hand stencils of European Paleolithic art tend to be considered of pre-Magdalenian age and scholars have generally assigned them to the Gravettian period. At El Castillo Cave, application of U-series dating to calcite accretions has established a minimum age of 37,290 years for underlying red hand stencils, implying execution in the earlier part of the Aurignacian if not beforehand. Together with the series of red disks, one of which has a minimum age of 40,800 years, these motifs lie at the base of the El Castillo parietal stratigraphy. The similarity in technique and colour support the notion that both kinds of artistic manifestations are synchronic and define an initial, non-figurative phase of European cave art. However, available data indicate that hand stencils continued to be painted subsequently. Currently, the youngest, reliably dated examples fall in the Late Gravettian, approximately 27,000 years ago.

  1. Little Ice Age versus Present Day: Comparison of Temperature, Precipitation and Seasonality in Speleothem Records from the Han-sur-Lesse Cave, Belgium.

    Science.gov (United States)

    Vansteenberge, S.; Van Opdenbosch, J.; Van Rampelbergh, M.; Verheyden, S.; Keppens, E.; Cheng, H.; Edwards, R. L.; Claeys, P. F.

    2015-12-01

    The Proserpine stalagmite is a 2 m large, tabular-shaped speleothem located in the Han-sur-Lesse cave in Belgium. The speleothem formed over the last 1000 years and is still growing. High-accuracy U/Th datings have indicated exceptionally high growth-rates of up to 2 mm per year. This, together with a well expressed annual layering, makes the Proserpine stalagmite an ideal candidate for high-resolution paleoclimate reconstructions of the last millennium. Previous work, including over 10 years of cave monitoring, has already learned us how short-term, i.e. decadal to seasonal, climate variations are incorporated within speleothem calcite from the Han-sur-Lesse cave system. It has been shown that δ18O and δ13C stable isotopes and trace element proxies of recently formed calcite reflect seasonal variations in temperature and precipitation of the near-cave environment (Verheyden et al, 2008; Van Rampelbergh et al., 2014). Now, this knowledge was used to infer local climate parameters further back in time to the period of +/- 1620-1630 CE, corresponding to one of the cold peaks within the Little Ice Age. Speleothem calcite was sampled at sub-annual resolution, with approximately 11 samples per year, for stable isotope analysis. LA-ICP-MS and µXRF analyses resulted in time series of trace elements. Preliminary results indicate a well expressed seasonal signal in δ13C and trace element composition but a multi-annual to decadal trend in δ18O. This combined proxy study eventually enables comparison of the expression of seasonality and longer term climate variations between a Little Ice Age cold peak and Present Day. References: Verheyden, S. et al., 2008, Monitoring climatological, hydrological and geochemical parameters in the Père Noël cave (Belgium): implication for the interpretation of speleothem isotopic and geochemical time-series. International Journal of Speleology, 37(3), 221-234. Van Rampelbergh, M. et al., 2014, Seasonal variations recorded in cave

  2. Speleothem records of acid sulphate deposition and organic carbon mobilisation

    Science.gov (United States)

    Wynn, Peter; Fairchild, Ian; Bourdin, Clement; Baldini, James; Muller, Wolfgang; Hartland, Adam; Bartlett, Rebecca

    2017-04-01

    Dramatic increases in measured surface water DOC in recent decades have been variously attributed to either temperature rise, or destabilisation of long-term soil carbon pools following sulphur peak emissions status. However, whilst both drivers of DOC dynamics are plausible, they remain difficult to test due to the restricted nature of the available records of riverine DOC flux (1978 to present), and the limited availability of SO2 emissions inventory data at the regional scale. Speleothems offer long term records of both sulphur and carbon. New techniques to extract sulphur concentrations and isotopes from speleothem calcite have enabled archives of pollution history and environmental acidification to be reconstructed. Due to the large dynamic range in sulphur isotopic values from end member sources (marine aerosol +21 ‰ to continental biogenic emissions -30 ‰) and limited environmental fractionation under oxidising conditions, sulphur isotopes form an ideal tracer of industrial pollution and environmental acidification in the palaeo-record. We couple this acidification history to the carbon record, using organic matter fluorescence and trace metals. Trace metal ratios and abundance can be used to infer the type and size of organic ligand and are therefore sensitive to changes in temperature as a driver of organic carbon processing and biodegradation. This allows fluorescent properties and ratios of trace metals in speleothem carbonate to be used to represent both the flux of organic carbon into the cave as well as the degradation pathway. Here we present some of the first results of this work, exploring sulphur acidification as a mechanistic control on carbon solubility and export throughout the twentieth century.

  3. A speleothem perspective on millennial-scale climate change in south-eastern Europe during the last glacial

    Directory of Open Access Journals (Sweden)

    Michael STAUBWASSER

    2014-11-01

    Full Text Available High-resolution stable O isotope data from two U-Th dated speleothems from Romania, one from Tăuşoare cave in N Romania spanning the last 68 ka, and one from Ascunsă cave in S Romania spanning the interval between  47 ka and  30 ka BP record a regional N-S climate contrast in SE Europe during marine isotope stage 3.  The Tăuşoare data-set records "Heinrich-stadial" type cold events (low δ18O throughout MIS 3. While the magnitude of speleothem δ18O variability in N Romania is much less pronounced in comparison to Sofular cave in NW Turkey, the pacing is generally similar. That suggests a common response to Atlantic millennial scale climate variability as observed in the Greenland record, but without the magnification of the δ18O signal observed in NW Turkey due to a local Black Sea source effect. The short time-interval recorded in Ascunsă cave (S Romania, however, shows virtually no similarity in δ18O with the corresponding section at Tăuşoare in N Romania, but instead resembles the record from Soreq cave (Israel.

  4. Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion–adsorption model of uranium uptake

    International Nuclear Information System (INIS)

    Cid, A.S.; Anjos, R.M.; Zamboni, C.B.; Cardoso, R.; Muniz, M.; Corona, A.; Valladares, D.L.

    2014-01-01

    Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion–adsorption (RDA) model is described. Unlike the classic diffusion–adsorption (D–A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ∪-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10 −12 cm 2 s −1 . Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved. - Highlights: • The Radial diffusion–adsorption (RDA) model is described. • RDA uses a cylindrical geometry to describe the U uptake in fossil bones. • We show new data for an extinct Macrauchenia patachonica from Uruguay. • Spatial distributions of Na, K, Ca, Mg, and U across a fossil bone section. • Gamma-ray spectrometric U-series dating was applied to determine its age

  5. U-Series Transport Studies at the Pena Blanca, Mexico Natural Analog Site

    Energy Technology Data Exchange (ETDEWEB)

    A. M. Simmons; M. T. Murrell

    2001-05-31

    Natural analogs provide a line of evidence that supports the understanding of how natural and engineered processes would occur over long time frames and large spatial scales at a potential nuclear waste repository at Yucca Mountain, Nevada. Studies of U-series disequilibria within and around uranium deposits can provide valuable information on the timing of actinide mobility and hence the stability of a potential repository over geologic time scales. The Nopal I uranium deposit at Pena Blanca, Mexico, is situated in unsaturated tuff that is similar in composition to the Topopah Spring Tuff of Yucca Mountain and closely matches other evaluation criteria for suitable natural analogs. By modeling the observed radioactive isotope disequilibria at Nopal I, we can estimate the rates of sorption-desorption and dissolution-precipitation of the radionuclides over time. Such information is vital to the testing or validation of performance assessment models for geologic nuclear waste disposal.

  6. U-Series Transport Studies at the Pena Blanca, Mexico Natural Analog Site

    International Nuclear Information System (INIS)

    Simmons, A. M.; Murrell, M. T.

    2001-01-01

    Natural analogs provide a line of evidence that supports the understanding of how natural and engineered processes would occur over long time frames and large spatial scales at a potential nuclear waste repository at Yucca Mountain, Nevada. Studies of U-series disequilibria within and around uranium deposits can provide valuable information on the timing of actinide mobility and hence the stability of a potential repository over geologic time scales. The Nopal I uranium deposit at Pena Blanca, Mexico, is situated in unsaturated tuff that is similar in composition to the Topopah Spring Tuff of Yucca Mountain and closely matches other evaluation criteria for suitable natural analogs. By modeling the observed radioactive isotope disequilibria at Nopal I, we can estimate the rates of sorption-desorption and dissolution-precipitation of the radionuclides over time. Such information is vital to the testing or validation of performance assessment models for geologic nuclear waste disposal

  7. U-series disequilibrium constraints on magma generation at the Jan Mayen hotspot

    Science.gov (United States)

    Rivers, E. R.; Chernow, R.; Elkins, L. J.; Sims, K. W.; Blichert-Toft, J.; Devey, C. W.

    2013-12-01

    The incompatible element-enriched magma source beneath the Jan Mayen Island hotspot influences melt generation on the adjacent northern Mid-Atlantic Ridge system and likely derives from either a small, local mantle plume, ancient Icelandic plume material emplaced in the mantle source, and/or sub-continental lithospheric mantle remnants emplaced locally by rifting of Greenland. The slow spreading Northern Kolbeinsey and Southern Mohns Ridges are immediately adjacent to Jan Mayen Island. Both have relatively shallow ridge axes, particularly the extremely shallow Eggvin Bank region of the Northern Kolbeinsey Ridge, which host anomalously large central volcanic edifices. We are currently collecting U-series disequilibrium and long-lived radiogenic isotope data for fresh, glassy mid-ocean ridge basalts from the Northern Kolbeinsey and Southern Mohns Ridge segments to better constrain source composition, depth of melting in the garnet peridotite stability field, solid mantle upwelling rates, and the nature of melt extraction beneath those segments. In particular, we are measuring isotopic data for geographically well-located samples collected from hummocky pillow basalt flows within the axial valley of the Northern Kolbeinsey Ridge segment as well as from the large volcanoes on both ridge segments, to further determine the role of the Jan Mayen hotspot in crustal construction on the Mid-Atlantic Ridge. Recently collected data show particularly high strontium isotope ratios consistent with trace element patterns that suggest a distinct local plume located beneath the Jan Mayen hotspot. A plume model for Jan Mayen is supported by new bathymetric imaging of adjacent ridge segments that reveals excess volcanism beneath the large axial volcanoes and a radial distribution of enrichment surrounding Jan Mayen Island. We predict that age-constrained U-series disequilibrium measurements will support active mantle upwelling focused beneath both Jan Mayen Island and the large axial

  8. Mushroom speleothems: Stromatolites that formed in the absence of phototrophs

    Science.gov (United States)

    Bontognali, Tomaso; D'Angeli, Ilenia; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano; Gonzales, Esteban; DeWaele, Jo

    2016-04-01

    Unusual speleothems resembling giant mushrooms occur in Santa Catalina Cave, Cuba. Although these mineral buildups are considered a natural heritage, their composition and formation mechanism remain poorly understood. Here we characterize their morphology and mineralogy and present a model for their genesis. We propose that the mushrooms, which are mainly comprised of calcite and aragonite, formed during four different phases within an evolving cave environment. The stipe of the mushroom is an assemblage of three well-known speleothems: a stalagmite surrounded by calcite rafts that were subsequently encrusted by cave clouds (mammilaries). More peculiar is the cap of the mushroom, which is morphologically similar to cerebroid stromatolites and thrombolites of microbial origin occurring in marine environments. Scanning electron microscopy investigations of this last unit revealed the presence of fossilized extracellular polymeric substances (EPS) - the constituents of biofilms and microbial mats. These organic microstructures are mineralized with Ca-carbonate, suggesting that the mushroom cap formed through a microbially-influenced mineralization process. The existence of cerebroid Ca-carbonate buildups forming in dark caves (i.e., in the absence of phototrophs) has interesting implications for the study of fossil microbialites preserved in ancient rocks, which are today considered as one of the earliest evidence for life on Earth.

  9. Mushroom speleothems: Stromatolites that formed in the absence of phototrophs

    Directory of Open Access Journals (Sweden)

    Tomaso eBontognali

    2016-04-01

    Full Text Available Unusual speleothems resembling giant mushrooms occur in Santa Catalina Cave, Cuba. Although these mineral buildups are considered a natural heritage, their composition and formation mechanism remain poorly understood. Here we characterize their morphology and mineralogy and present a model for their genesis. We propose that the mushrooms, which are mainly comprised of calcite and aragonite, formed during four different phases within an evolving cave environment. The stipe of the mushroom is an assemblage of three well-known speleothems: a stalagmite surrounded by calcite rafts that were subsequently encrusted by cave clouds (mammilaries. More peculiar is the cap of the mushroom, which is morphologically similar to cerebroid stromatolites and thrombolites of microbial origin occurring in marine environments. Scanning electron microscopy investigations of this last unit revealed the presence of fossilized extracellular polymeric substances (EPS – the constituents of biofilms and microbial mats. These organic microstructures are mineralized with Ca-carbonate, suggesting that the mushroom cap formed through a microbially-influenced mineralization process. The existence of cerebroid Ca-carbonate buildups forming in dark caves (i.e., in the absence of phototrophs has interesting implications for the study of fossil microbialites preserved in ancient rocks, which are today considered as one of the earliest evidence for life on Earth.

  10. Calcium carbonate concretions in caves : an overview

    International Nuclear Information System (INIS)

    Gewelt, M.; Ek, C.

    1988-01-01

    The scientific work of the last twenty years on calcium carbonate cave deposits (dripstones and flowstones) is presented. Recent studies on speleothems composition, growth, age and paleoclimatic environment are examined. Main new results are related with the development of isotopic and radiometric dating methods. Increasing numbers of dates allow for statistical speleothem repartition studies which could be related with paleoclimates. Two new frequency curves of U-series ages data of speleothems are given. (M.C.B.)

  11. Direct dating of human fossils.

    Science.gov (United States)

    Grün, Rainer

    2006-01-01

    The methods that can be used for the direct dating of human remains comprise of radiocarbon, U-series, electron spin resonance (ESR), and amino acid racemization (AAR). This review gives an introduction to these methods in the context of dating human bones and teeth. Recent advances in ultrafiltration techniques have expanded the dating range of radiocarbon. It now seems feasible to reliably date bones up to 55,000 years. New developments in laser ablation mass spectrometry permit the in situ analysis of U-series isotopes, thus providing a rapid and virtually non-destructive dating method back to about 300,000 years. This is of particular importance when used in conjunction with non-destructive ESR analysis. New approaches in AAR analysis may lead to a renaissance of this method. The potential and present limitations of these direct dating techniques are discussed for sites relevant to the reconstruction of modern human evolution, including Florisbad, Border Cave, Tabun, Skhul, Qafzeh, Vindija, Banyoles, and Lake Mungo. (c) 2006 Wiley-Liss, Inc.

  12. Sr isotopes and U series radionuclides in the Sangemini area (Central Italy: Hydrogeology implications

    Directory of Open Access Journals (Sweden)

    Maurizio Barbieri

    2014-06-01

    Full Text Available The strontium isotopic ratio (expressed as 87Sr/86Sr of groundwater represents a useful method for studying and understanding the groundwater circulations, also, the U and Ra isotopic compositions can vary as function of the groundwater residence time. This paper reports an evaluation of the probable recharge area of the Sangemini mineral water springs (Terni-Umbria Central Italy and an estimate of the residence time of the aquifer by coupling Sr and U series isotopic systematics. For this study have been analyzed four water sample for the isotope ratio of 87Sr/86Sr, and eleven samples, shallow waters and groundwaters, for U and Ra, furthermore were determined the values of isotopic ratio for sample of typical rocks of the area. The results of this study allow to identify: a recharge area in a restricted sector of the Meso-Cenozoic carbonates a longer and more effective water/rock interaction in the Quaternary series. U and Ra recoil models allow to estimate a groundwater residence time of about 350 years and a total water volume whose value (64*106 m3 agrees with the limited extension of the aquifer. The extension of the aquifer was constrained by comparing Sr isotopic composition of waters and local geological formations. Groundwaters seem mainly to circulate in clayey sandy Quaternary series characterized by low redox conditions.

  13. A MIS 9/MIS 8 speleothem record of hydrological variability from Macedonia (F.Y.R.O.M.)

    Science.gov (United States)

    Regattieri, Eleonora; Zanchetta, Giovanni; Isola, Ilaria; Bajo, Petra; Perchiazzi, Natale; Drysdale, Russell N.; Boschi, Chiara; Hellstrom, John C.; Francke, Alexander; Wagner, Bernd

    2018-03-01

    The period corresponding to Marine Isotope Stages 9 (MIS 9) offers the opportunity to study orbital and sub-orbital scale climate variability under boundary conditions different from those of better studied intervals such as the Holocene and the Last Interglacial. Yet, it is poorly represented in independently-dated continental archives around the Mediterranean Region. Here, we present a speleothem stable isotope record (δ18O and δ13C) from the Former Yugoslavian Republic of Macedonia (F.Y.R.O.M., southern Balkans), which consists of two periods of growth broadly covering the ca. 332 to 292 ka and the ca. 264 to 248 ka intervals (MIS 9e-b and late MIS 8). We interpret the speleothem δ18O as mostly related to regional hydrology, with variations that can be interpreted as due to changes in rainfall amount, with higher/lower values associated to drier/wetter condition. This interpretation is corroborated by a change in mineralogical composition between aragonite and calcite at ca. 328 ka, which marks increasing precipitation at the onset of MIS 9 and occurs within a trend of decreasing δ18O values. Also the comparison with the multiproxy climate record available from the nearby Lake Ohrid seems to support the proposed interpretation. The MIS 9e interglacial appears to be characterized by wettest conditions between ca. 326 and 321 ka, i.e. lasting ca. 5 kyr. Decreasing precipitation and enhanced millennial scale variability matches the glacial inception (MIS9 d to b), with drier events at ca. 319 ka (ca. 2 kyr long) and 310 ka (ca. 1 kyr long), and a major rainfall reduction between 306 and 298 ka. The latter is followed by a prominent wetter period between 298 and 295 ka, for which carbon data values suggest high infiltration rate. Rainfall decreases again after 295 ka, and remain low until the growth interruption at ca. 292 ka. Resumption of the growth and progressive soil development, expressed by the carbon isotope record, occurred during the late part of MIS 8

  14. A high-resolution Holocene speleothem record from NE Romania: the nexus of Arctic and North Atlantic atmospheric circulations

    Science.gov (United States)

    Constantin, S.; Pourmand, A.; Moldovan, O.; Sharifi, A.; Mehterian, S.; Swart, P. K.

    2017-12-01

    The Romanian Carpathians act as a geomorphological barrier between different atmospheric circulation systems over Central and Eastern Europe; the NW of Romania lies under the remote influence of the North Atlantic oscillation, while the NE is influenced by the Arctic climate. In NW Romania, previous stable isotope studies of speleothems have not yielded a clear account of abrupt climate oscillations during the Holocene. Here we present results from a stalagmite collected from the Tauşoare Cave, located in NE Carpathians. The chronology of stalagmite T141 is based on 15 high-precision Th/U dates ranging between 32 and 1.1 ka with a continuous growth between 13.3 and 1.1 ka. The portion of the record within the Holocene was analyzed for δ18O and δ13C at a resolution ranging between 15 to 200 years/sample. The resulting δ18O record captures the Younger Dryas (YD) event centered at 12.9 ka, with δ18O values about 4 ‰ more depleted than those corresponding to the Holocene Climatic Optimum. The 8.2 ka event appears to be also captured in the record, although less prominent. The T141 isotope record is significantly different when compared to coeval records measured in speleothems from NW Carpathians, which do not exhibit marked changes during the YD or 8.2 ka events. This is likely due to the contrasting effect of temperature and atmospheric transport on δ18O signal in NW Romania. Within a distance of 200 km to the east, on the eastern flank of the Carpathian range, the δ18O signal of the Arctic circulation appears to be more prominent and clearly exhibits a positive relationship with temperature changes.

  15. Direct U-series analysis of the Lezetxiki humerus reveals a Middle Pleistocene age for human remains in the Basque Country (northern Iberia).

    Science.gov (United States)

    de-la-Rúa, Concepción; Altuna, Jesús; Hervella, Monserrat; Kinsley, Leslie; Grün, Rainer

    2016-04-01

    In 1964, a human humerus was found in a sedimentary deposit in Lezetxiki Cave (Basque Country, northern Iberia). The first studies on the stratigraphy, associated mammal faunal remains and lithic implements placed the deposits containing the humerus into the Riss glacial stage. Direct chronometric evidence has so far been missing, and the previous chronostratigraphic framework and faunal dating gave inconsistent results. Here we report laser ablation U-series analyses on the humerus yielding a minimum age of 164 ± 9 ka, corresponding to MIS 6. This is the only direct dating analysis of the Lezetxiki humerus and confirms a Middle Pleistocene age for this hominin fossil. Morphometric analyses suggest that the Lezetxiki humerus has close affinities to other Middle Pleistocene archaic hominins, such as those from La Sima de los Huesos at Atapuerca. This emphasizes the significance of the Lezetxiki fossil within the populations that predate the Neanderthals in south-western Europe. It is thus an important key fossil for the understanding of human evolution in Europe during the Middle Pleistocene, a time period when a great morphological diversity is observed but whose phylogenetic meaning is not yet fully understood. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. A Robust Analysis Method For Δ13c Signal Of Bulk Organic Matter In Speleothems

    Science.gov (United States)

    Bian, F.; Blyth, A. J.; Smith, C.; Baker, A.

    2017-12-01

    Speleothems preserve organic matter that is derived from both the surface soil and cave environments. This organic matter can be used to understand paleoclimate and paleoenvironments. However, a stable and quick micro-analysis method to measure the δ13C signals from speleothem organic matter separate from the total δ13C remains absent. And speleothem organic geochemistry is still relatively unexplored compared to inorganic geochemistry. In this research, for the organic matter analysis, bulk homogeneous power samples were obtained from one large stalagmite. These were dissolved by phosphoric acid to produce the aqueous solution. Then, the processed solution was degassed through a rotational vacuum concentrator. A liquid chromatograph was coupled to IRMS to control the oxidization and the measurement of analytes. This method is demonstrated to be robust for the analysis of speleothem d13C organic matter analysis under different preparation and instrumental settings, with the low standard deviation ( 0.2‰), and low sample consumption (<25 mg). Considering the complexity of cave environments, this method will be useful in further investigations the δ13C of entrapped organic matter and environmental controls in other climatic and ecological contexts, including the determination of whether vegetation or soil microbial activity is the dominant control on speleothem d13C of organic matter.

  17. 238U-series radionuclides in Finnish groundwater-based drinking water and effective doses

    International Nuclear Information System (INIS)

    Vesterbacka, P.

    2005-09-01

    The thesis deals with the occurrence of 238 U-series radionuclides and particle-bound 210 Pb and 210 Po in Finnish groundwater-based drinking water, methods used for removing 234 U, 238 U, 210 Pb and 210 Po, and the annual effective doses caused by 238 U-series radionuclides in drinking water. In order to reduce radiation exposure and avoid high doses, it is important to examine the activity levels of natural radionuclides in groundwater. In this work, the activity concentrations of radon ( 222 Rn), radium ( 226 Ra), uranium ( 238 U and 234 U), lead ( 210 Pb) and polonium ( 210 Po) were determined from 472 private wells, which were selected randomly from across Finland. On the basis of the results, the activity concentrations in groundwater and the radiation exposure from drinking water of people living outside the public water supply in Finland was specified. The efficiency of 238 U, 234 U, 210 Pb and 210 Po removal from drinking water was examined at ten private homes. In order to obtain accurate results and correct estimates of effective doses, attention was paid to the sampling of 222 Rn and 210 Pb, and the determination of 210 Pb. The results revealed that the median activity concentrations of natural radionuclides were as much as ten times higher in drilled wells than in wells dug in soil. The average activity concentration of 222 Rn in drilled wells was 460 Bq/l and in dug wells 50 Bq/l. The highest activity concentrations were found in Southern Finland. In addition, occasional high activity concentrations were found all over Finland. The average activity concentrations of 234 U and 238 U in drilled wells were 0.35 and 0.26 Bq/l and in dug wells 0.020 and 0.015 Bq/l, respectively. The spatial distribution of 234 U, 238 U, 210 Pb and 210 Po was essentially similar to that of 222 Rn. In contrast to other natural radionuclides, the highest 226 Ra activity concentrations were found in coastal areas, since drilled well water near the sea has a higher salinity

  18. Medieval climate anomaly and little ice age as recorded in speleothem and tree-ring data from the Middle Atlas in Morocco

    Science.gov (United States)

    Wassenburg, J. A.; Immenhauser, A.; Richter, D. K.; Fietzke, J.; Scholz, D.; Jochum, K. P.; Riechelmann, D. F. C.; Schneider, L.; Esper, J.

    2012-04-01

    Progress has recently been made in assessing the spatial extend and timing of the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) on hemispheric and global scales (Graham et al. 2011). Uncertainties still exist, however, since the transition from the MCA into the LIA seems to be diachronous, and in many cases, reconstructions are based on single climate archives (e.g., speleothems, tree-rings, or pollen data). In Morocco, cedar trees from the Middle and High Atlas have been used to reconstruct the Palmer Drought Severity Index (PDSI) back to 1049 AD (Esper et al., 2007), a metric integrating the evaporation-precipitation balance and soil properties. According to Graham et al. (2011), the MCA/LIA transition recorded in Moroccan tree rings occurred rather late (around 1400 AD) in comparison to the reconstructed winter temperature in the European Alps (e.g., Mangini et al., 2005), which show substantial changes about 50 years earlier. Here we compare precisely dated speleothem δ13C and trace element records from the Middle Atlas with an updated version of the tree-ring based PDSI reconstruction from Esper et al. (2007). Both stalagmite δ13C and strontium records support the prevalence of exceptionally dry conditions during the MCA and relatively wet conditions during the LIA. These changes have formerly been suggested to be related to persistent positive and negative phases of the North Atlantic Oscillation (Trouet et al., 2009). The speleothem based reconstruction extends back to 700 AD and, thus, provides insight on the precise timing of the driest period during the MCA in the Moroccan Middle Atlas.

  19. Behaviour of U-Series Radionuclides in an Estuary Affected by Acid Mine Drainage and Industrial Releases

    Energy Technology Data Exchange (ETDEWEB)

    Hierro, A.; Bolivar, J. P.; Vaca, F. [Department of Applied Physics, University of Huelva, Huelva (Spain)

    2013-07-15

    The estuary formed by the Tinto and Odiel rivers is an ecosystem of great interest because it is seriously affected by the acid mine drainage (AMD) produced by the high mining activity in the watersheds of these rivers, generating in their waters an extremely low pH (2.5- 3.5), and consequently high concentrations of heavy metals and natural radionuclides in dissolution. Secondly, in their estuary there is a large chemical industrial complex, and in particular two phosphoric acid production plants, which use a sedimentary phosphate rock from Morocco as raw material containing at approximately 1.5 Bq/g of U-series radionuclides, which produce annually about 2.5-3 millions of tonnes of a byproduct, called phosphogypsum (PG). PG contains high concentrations of some U-series radionuclides as {sup 226}Ra (650 Bq/kg), {sup 210}Pb-{sup 210}Po (600 Bq/kg) or {sup 230}Th (450 Bq/kg). Seventeen sampling stations along the end of these rivers and this estuary were selected to study the behaviour of U-series radionuclides in the recent surface sediments and its waters. The most relevant results show a non-conservative behaviour of Uisotopes, precipitating in the zone where large pH changes (3-5) are produced. This behaviour is different from the majority of typical estuaries where only salinity changes are produced, and therefore, a conservative behaviour of uranium is observed. (author)

  20. Combined ESR/U-series chronology of Acheulian hominid-bearing layers at Trinchera Galería site, Atapuerca, Spain.

    Science.gov (United States)

    Falguères, Christophe; Bahain, Jean-Jacques; Bischoff, James L; Pérez-González, Alfredo; Ortega, Ana Isabel; Ollé, Andreu; Quiles, Anita; Ghaleb, Bassam; Moreno, Davinia; Dolo, Jean-Michel; Shao, Qingfeng; Vallverdú, Josep; Carbonell, Eudald; Bermúdez de Castro, Jose María; Arsuaga, Juan Luis

    2013-08-01

    The Sierra de Atapuerca, northern Spain, is known from many prehistoric and palaeontological sites documenting human prehistory in Europe. Three major sites, Gran Dolina, Galería and Sima del Elefante, range in age from the oldest hominin of Western Europe dated to 1.1 to 1.3 Ma (millions of years ago) at Sima del Elefante to c.a. 0.2 Ma on the top of the Galería archaeological sequence. Recently, a chronology based on luminescence methods (Thermoluminescence [TL] and Infrared Stimulated Luminescence [IRSL]) applied to cave sediments was published for the Gran Dolina and Galería sites. The authors proposed for Galería an age of 450 ka (thousands of years ago) for the units lower GIII and GII, suggesting that the human occupation there is younger than the hominid remains of Sima de los Huesos (>530 ka) around 1 km away. In this paper, we present new results obtained by combined Electron Spin Resonance/Uranium-series (ESR/U-series) dating on 20 herbivorous teeth from different levels at the Galería site. They are in agreement with the TL results for the upper part of the stratigraphic sequence (GIV and GIIIb), in the range of between 200 and 250 ka. But for the GIIIa to GIIb levels, the TL ages become abruptly older by 200 ka while ESR ages remain relatively constant. Finally, the TL and ESR data agree in the lowest part of the section (GIIa); both fall in the range of around 350-450 ka. Our results suggest a different interpretation for the GII, GIII and GIV units of Galería and the upper part of Gran Dolina (TD10 and TD11) than obtained by TL. The ESR/U-series results are supported by a Bayesian analysis, which allows a better integration between stratigraphic information and radiometric data. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Past climate variability between 97 and 7 ka reconstructed from a multi proxy speleothem record from Western Cuba

    Science.gov (United States)

    Winterhalder, Sophie; Scholz, Denis; Mangini, Augusto; Spötl, Christoph; Jochum, Klaus Peter; Pajón, Jesús M.

    2016-04-01

    The tropical hydrological cycle plays a key role in regulating global climate, mainly through the export of heat and moisture to higher latitudes, and is highly sensitive to climate change, for instance due to changes in the position of the Intertropical Convergence Zone (ITCZ). Previous work on Caribbean stalagmites suggests a strong connection of precipitation variability to North Atlantic (NA) sea surface temperatures on multidecadal to millenial timescales (Fensterer et al., 2012; Fensterer et al., 2013; Winter et al., 2011). Cold phases in the NA potentially lead to a southward shift of the ITCZ and thus drier conditions in Cuba. On orbital timescales, Cuban stalagmites suggest a relation of speleothem δ18O values with the δ18O value of Caribbean surface waters (Fensterer et al., 2013). Here we present an expansion of the Cuban speleothem record covering the whole last glacial period from the end of MIS5c (97 ka BP) until 7 ka with hiatuses between 93-80 ka, 37-35 ka and 13-10 ka. Stalagmite Cuba medio (CM) has been precisely dated with 60 230Th/U-ages, mainly performed by the MC-ICPMS technique. The δ18O and δ13C records are completed by a continuous, high resolution LA-ICPMS trace element profile. These data allow for the first time to establish a multi-proxy climate reconstruction for the North Western Caribbean at decadal to centennial resolution for this period. The long-term variability of the δ18O values probably reflects rainfall amount in Cuba. The response to some Dansgaard/Oeschger and Heinrich stadials confirms the previously observed correlation between Caribbean and NA climate variability. However, this connection is not clearly imprinted throughout the record. Furthermore, trace elements, such as Mg, do not proof without ambiguity drier conditions in Cuba during NA cold events, such as the Heinrich stadials. This suggests that climate variability in Cuba was more complex during the last 100ka, and that the NA was not the only driving factor

  2. A Holocene Record of Monsoon Intensity From Speleothems in Flores, Indonesia

    Science.gov (United States)

    Griffiths, M. L.; Drysdale, R.; Gagan, M.; Ayliffe, L.; Zhao, J.; St. Pierre, E.; Hantoro, W.; Suwargadi, B.

    2007-12-01

    The Australasian monsoon is among the largest monsoon systems on Earth. The affected region experiences a marked seasonal cycle in winds and precipitation, similar to its Northern Hemisphere counterparts (e.g., Asian monsoons). The Australasian monsoon is the life blood of the millions of people of the Indonesian archipelago. Since the climate is the dominating factor controlling food production, it is of great significance and urgency that we gain a firmer grasp on the parameters that control variations in monsoon intensity. Precise uranium series dating of two actively growing speleothems measuring ~1.25 (LR06-B1) and ~1.61 (LR06-B3) meters in length from Liang Luar cave (Flores, eastern Indonesia), reveal basal ages of ~12,846±103 and 23,605±171 years respectively. In previous studies, stable isotope ratios (δ18O and δ13C) and trace element concentrations in speleothems have revealed past environmental change (e.g., Burns et al., 2001; Wang et al., 2001; Fleitmann et al., 2004; Drysdale et al., 2004).In monsoon-affected regions, the δ18O signal recorded in stalagmites seems to be dominated by the amount of precipitation (so-called `amount effect'), whereby more negative (positive) δ18O values indicate enhanced (diminished) precipitation. Preliminary results from LR06-B1 indicate that δ18O values show a general increase in monsoon intensity from the beginning of the record to ~2000 years BP: this more or less follows insolation changes over the Australian continent.Comparison of our record with D4 from Dongge Cave reveals an anticorrelation during the Holocene, further supporting the hypothesis that tropical monsoon intensity is largely controlled by changes in insolation in both the Northern and Southern Hemisphere. Examination of our δ13C record demonstrates a high-frequency signal superimposed on low- frequency variability which correlates with the reconstructed sunspot cycle: higher (lower) sunspot numbers, and hence increased solar activity

  3. Modeling of U-series Radionuclide Transport Through Soil at Pena Blanca, Chihuahua, Mexico

    Science.gov (United States)

    Pekar, K. E.; Goodell, P. C.; Walton, J. C.; Anthony, E. Y.; Ren, M.

    2007-05-01

    The Nopal I uranium deposit is located at Pena Blanca in Chihuahua, Mexico. Mining of high-grade uranium ore occurred in the early 1980s, with the ore stockpiled nearby. The stockpile was mostly cleared in the 1990s; however, some of the high-grade boulders have remained there, creating localized sources of radioactivity for a period of 25-30 years. This provides a unique opportunity to study radionuclide transport, because the study area did not have any uranium contamination predating the stockpile in the 1980s. One high-grade boulder was selected for study based upon its shape, location, and high activity. The presumed drip-line off of the boulder was marked, samples from the boulder surface were taken, and then the boulder was moved several feet away. Soil samples were taken from directly beneath the boulder, around the drip-line, and down slope. Eight of these samples were collected in a vertical profile directly beneath the boulder. Visible flakes of boulder material were removed from the surficial soil samples, because they would have higher concentrations of U-series radionuclides and cause the activities in the soil samples to be excessively high. The vertical sampling profile used 2-inch thicknesses for each sample. The soil samples were packaged into thin plastic containers to minimize the attenuation and to standardize sample geometry, and then they were analyzed by gamma-ray spectroscopy with a Ge(Li) detector for Th-234, Pa-234, U-234, Th-230, Ra-226, Pb-214, Bi-214, and Pb-210. The raw counts were corrected for self-attenuation and normalized using BL-5, a uranium standard from Beaverlodge, Saskatchewan. BL-5 allowed the counts obtained on the Ge(Li) to be referenced to a known concentration or activity, which was then applied to the soil unknowns for a reliable calculation of their concentrations. Gamma ray spectra of five soil samples from the vertical profile exhibit decreasing activities with increasing depth for the selected radionuclides

  4. Early Holocene humidity patterns in the Iberian Peninsula reconstructed from lake, pollen and speleothem records

    Science.gov (United States)

    Morellón, Mario; Aranbarri, Josu; Moreno, Ana; González-Sampériz, Penélope; Valero-Garcés, Blas L.

    2018-02-01

    Comparison of selected, well-dated, lacustrine, speleothem and terrestrial pollen records spanning the Holocene onset and the Early Holocene (ca. 11.7-8 cal kyrs BP) in the Iberian Peninsula shows large hydrological fluctuations and landscape changes with a complex regional pattern in timing and intensity. Marine pollen records from Alboran, the Mediterranean and off shore Atlantic sites show a step-wise increase in moisture and forest during this transition. However, available continental records point to two main patterns of spatial and temporal hydrological variability: i) Atlantic-influenced sites located at the northwestern areas (Enol, Sanabria, Lucenza, PRD-4), characterized by a gradual increase in humidity from the end of the Younger Dryas to the Mid Holocene, similarly to most North Atlantic records; and ii) continental and Mediterranean-influenced sites (Laguna Grande, Villarquemado, Fuentillejo, Padul, Estanya, Banyoles, Salines), with prolonged arid conditions of variable temporal extension after the Younger Dryas, followed by an abrupt increase in moisture at 10-9 cal kyrs BP. Different local climate conditions influenced by topography or the variable sensitivity (gradual versus threshold values) of the proxies analyzed in each case are evaluated. Vegetation composition (conifers versus mesothermophilous taxa) and resilience would explain a subdued response of vegetation in central continental areas while in Mediterranean sites, insufficient summer moisture availability could not maintain high lake levels and promote mesophyte forest, in contrast to Atlantic-influenced areas. Comparison with available climate models, Greenland ice cores, North Atlantic marine sequences and continental records from Central and Northern Europe and the whole Mediterranean region underlines the distinctive character of the hydrological changes occurred in inner Iberia throughout the Early Holocene. The persistent arid conditions might be explained by the intensification

  5. ESR dating of tooth enamel samples

    International Nuclear Information System (INIS)

    Chen Tiemei; Yang quan; Wu En

    1993-01-01

    Five tooth samples from the palaeoanthropological site of Jinniushan were dated with both electron-spin-resonance (ESR) and uranium-series techniques. The ESR age of about 230 ka is in good agreement with the U-series dating result, which confirms the hypothesis of possible coexistence of Homo erect us and Homo sapiens in China. Problems in ESR dating are discussed such as: 1) inappropriate of simple exponential extrapolation for accumulated dose determination; 2)experimental measurement of alpha detection efficiency and radon emanation and 3)selection of U-uptake model

  6. Three centuries of heavy metal pollution in Paris (France) recorded by urban speleothems.

    Science.gov (United States)

    Pons-Branchu, Edwige; Ayrault, Sophie; Roy-Barman, Matthieu; Bordier, Louise; Borst, Wolfgang; Branchu, Philippe; Douville, Eric; Dumont, Emmanuel

    2015-06-15

    The first record of urban speleothems used to reconstruct the history of heavy metal pollution of shallow groundwaters is presented. Two speleothems grew during the last 300 years in an underground aqueduct in the north-eastern part of Paris. They display high Pb, Mn V, Cu, Cd and Al concentrations since 1900 due to the urbanization of the site which triggered anthropogenic contamination of the water feeding the speleothems. Surprisingly, these heavy metal concentrations are also high in the oldest part. This early pollution could come from the use of Parisian waste as fertilizers in the orchards and vineyards cultivated above the aqueduct before urbanization. Lead isotopes were measured in these carbonates as well as in lead artifacts from the 17th-18th centuries ((206)Pb/(207)Pb=1.180+/-0.003). The mean (206)Pb/(207)Pb ratio, for one of the speleothems is 1.181+/-0.003 unvarying with time. These lead signatures are close to those of coal and old lead from northern European mines, lower than the natural background signature. It confirms that the high metal concentrations found come from anthropogenic pollution. Conversely, the lead isotopic composition of the second speleothem presents two temporal trends: for the oldest levels, the mean value (1.183+/-0.003) is similar to the first speleothem. For the youngest part, a lower value (1.172+/-0.005) is recorded, evidencing the contribution of a new lead source at the beginning of the industrial revolution. Pb isotopes were also measured in recent samples from a nearby superficial site. The first sample is a recent (AD 1975+/-15 years) deposit ((206)Pb/(207)Pb=1.148+/-0.003), and the second, a thin subactual layer ((206)Pb/(207)Pb=1.181+/-0.002). These data are compatible with the adding of anthropogenic sources (leaded gasoline and industrial lead from Rio Tinto ore). Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Three centuries of heavy metal pollution in Paris (France) recorded by urban speleothems

    International Nuclear Information System (INIS)

    Pons-Branchu, Edwige; Ayrault, Sophie; Roy-Barman, Matthieu; Bordier, Louise; Borst, Wolfgang; Branchu, Philippe; Douville, Eric; Dumont, Emmanuel

    2015-01-01

    The first record of urban speleothems used to reconstruct the history of heavy metal pollution of shallow groundwaters is presented. Two speleothems grew during the last 300 years in an underground aqueduct in the north-eastern part of Paris. They display high Pb, Mn V, Cu, Cd and Al concentrations since 1900 due to the urbanization of the site which triggered anthropogenic contamination of the water feeding the speleothems. Surprisingly, these heavy metal concentrations are also high in the oldest part. This early pollution could come from the use of Parisian waste as fertilizers in the orchards and vineyards cultivated above the aqueduct before urbanization. Lead isotopes were measured in these carbonates as well as in lead artifacts from the 17th–18th centuries ( 206 Pb/ 207 Pb = 1.180 +/− 0.003). The mean 206 Pb/ 207 Pb ratio, for one of the speleothems is 1.181 +/− 0.003 unvarying with time. These lead signatures are close to those of coal and old lead from northern European mines, lower than the natural background signature. It confirms that the high metal concentrations found come from anthropogenic pollution. Conversely, the lead isotopic composition of the second speleothem presents two temporal trends: for the oldest levels, the mean value (1.183 +/− 0.003) is similar to the first speleothem. For the youngest part, a lower value (1.172 +/− 0.005) is recorded, evidencing the contribution of a new lead source at the beginning of the industrial revolution. Pb isotopes were also measured in recent samples from a nearby superficial site. The first sample is a recent (AD 1975 +/− 15 years) deposit ( 206 Pb/ 207 Pb = 1.148 +/− 0.003), and the second, a thin subactual layer ( 206 Pb/ 207 Pb = 1.181 +/− 0.002). These data are compatible with the adding of anthropogenic sources (leaded gasoline and industrial lead from Rio Tinto ore). - Highlights: • Urban speleothems from underground aqueduct in Paris, France were studied. • Speleothems are

  8. Three centuries of heavy metal pollution in Paris (France) recorded by urban speleothems

    Energy Technology Data Exchange (ETDEWEB)

    Pons-Branchu, Edwige, E-mail: epons@lsce.ipsl.fr [LSCE (UMR8212, CEA/CNRS/UVSQ), Bâtiment 12, avenue de la Terrasse, 91198 Gif-Sur-Yvette (France); Ayrault, Sophie; Roy-Barman, Matthieu; Bordier, Louise [LSCE (UMR8212, CEA/CNRS/UVSQ), Bâtiment 12, avenue de la Terrasse, 91198 Gif-Sur-Yvette (France); Borst, Wolfgang; Branchu, Philippe [CEREMA, 12 rue Teisserenc de Bort, 78190 Trappes (France); Douville, Eric [LSCE (UMR8212, CEA/CNRS/UVSQ), Bâtiment 12, avenue de la Terrasse, 91198 Gif-Sur-Yvette (France); Dumont, Emmanuel [CEREMA, rue de l' égalité Prolongée, 93352, Le Bourget cedex 319 (France)

    2015-06-15

    The first record of urban speleothems used to reconstruct the history of heavy metal pollution of shallow groundwaters is presented. Two speleothems grew during the last 300 years in an underground aqueduct in the north-eastern part of Paris. They display high Pb, Mn V, Cu, Cd and Al concentrations since 1900 due to the urbanization of the site which triggered anthropogenic contamination of the water feeding the speleothems. Surprisingly, these heavy metal concentrations are also high in the oldest part. This early pollution could come from the use of Parisian waste as fertilizers in the orchards and vineyards cultivated above the aqueduct before urbanization. Lead isotopes were measured in these carbonates as well as in lead artifacts from the 17th–18th centuries ({sup 206}Pb/{sup 207}Pb = 1.180 +/− 0.003). The mean {sup 206}Pb/{sup 207}Pb ratio, for one of the speleothems is 1.181 +/− 0.003 unvarying with time. These lead signatures are close to those of coal and old lead from northern European mines, lower than the natural background signature. It confirms that the high metal concentrations found come from anthropogenic pollution. Conversely, the lead isotopic composition of the second speleothem presents two temporal trends: for the oldest levels, the mean value (1.183 +/− 0.003) is similar to the first speleothem. For the youngest part, a lower value (1.172 +/− 0.005) is recorded, evidencing the contribution of a new lead source at the beginning of the industrial revolution. Pb isotopes were also measured in recent samples from a nearby superficial site. The first sample is a recent (AD 1975 +/− 15 years) deposit ({sup 206}Pb/{sup 207}Pb = 1.148 +/− 0.003), and the second, a thin subactual layer ({sup 206}Pb/{sup 207}Pb = 1.181 +/− 0.002). These data are compatible with the adding of anthropogenic sources (leaded gasoline and industrial lead from Rio Tinto ore). - Highlights: • Urban speleothems from underground aqueduct in Paris, France were

  9. The calcareous speleothems in the pseudokarst Jaskinia Slowianska-Drwali cave, Beskid Niski Mts., Poland

    Czech Academy of Sciences Publication Activity Database

    Urban, J.; Margielewski, W.; Žák, Karel; Hercman, H.; Sujka, G.; Mleczek, T.

    2007-01-01

    Roč. 63, č. 6 (2007), s. 119-128 ISSN 1643-9252 R&D Projects: GA ČR GA205/02/0449 Institutional research plan: CEZ:AV0Z30130516 Keywords : speleothems * pseudokarst * Carpathians Subject RIV: DB - Geology ; Mineralogy

  10. Environmentally acceptable effect of hydrogen peroxide on cave 'lamp-flora', calcite speleothems and limestones

    International Nuclear Information System (INIS)

    Faimon, Jiri; Stelcl, Jindrich; Kubesova, Svatava; Zimak, Jiri

    2003-01-01

    Hydrogen peroxide plus limestone fragments allows removal of organisms without corrosion of limestone and speleothem. - Mosses, algae, and cyanobacteria (lamp-flora) colonize illuminated areas in show caves. This biota is commonly removed by a sodium hypochlorite solution. Because chlorine and other deleterious compounds are released into a cave environment during lamp-flora cleansing, hydrogen peroxide was tested as an alternative agent. In a multidisciplinary study conducted in the Katerinska Cave (Moravian Karst, Czech Republic), 12 algae- and cyanobacteria taxons and 19 moss taxons were detected. The threshold hydrogen peroxide concentration for the destruction of this lamp-flora was found to be 15 vol.%. Based on laboratory experiments in stirred batch reactors, the dissolution rates of limestones and calcite speleothems in water were determined as 3.77x10 -3 and 1.81x10 -3 mol m -2 h -1 , respectively. In the 15% peroxide solution, the limestone and speleothem dissolution rates were one order of magnitude higher, 2.00x10 -2 and 2.21x10 -2 mol m -2 h -1 , respectively. So, the peroxide solution was recognised to attack carbonates somewhat more aggressively than karst water. In order to prevent the potential corrosion of limestone and speleothems, the reaching of preliminary peroxide saturation with respect to calcite is recommended, for example, by adding of few limestone fragments into the solution at least 10 h prior to its application

  11. 20 years of speleothem paleoluminescence records of environmental changes: an overview

    Directory of Open Access Journals (Sweden)

    Shopov Yavor Y.

    2004-12-01

    Full Text Available This paper discusses advance of the research on Speleothem paleoluminescence Records of Environmental Changes after it have been first introduced by the author 20 years ago.It is demonstrated that most of the progress in this field was made in result of the operation of the International Program “Luminescence of Cave Minerals” of the commission on Physical Chemistry and Hydrogeology of Karst of UIS of UNESCO.Potential, resolution and limitations of high resolution luminescence speleothem proxy records of Paleotemperature, Solar Insolation, Solar Luminosity, Glaciations, Sea Level advances, Past Precipitation, Plants Populations, Paleosoils, Past Karst Denudation, Chemical Pollution, Geomagnetic field and Cosmic Rays Flux variations, Cosmogenic Isotopes production and Supernova Eruptions in the Past, Advances of Hydrothermal Waters, and Tectonic Uplift are discussed.It is demonstrated that speleothems allow extremely high resolution (higher than in any other paleoclimatic terrestrial archives and long duration of records. Some speleothems can be used as natural climatic stations for obtaining of quantitative proxy records of Quaternary climates with annual resolution.

  12. Relationship between oxygen isotopes in rainfall, cave percolation waters and speleothem calcite at Waitomo, New Zealand

    International Nuclear Information System (INIS)

    Williams, P.W.; Fowler, A.

    2002-01-01

    The relationship between the δ 18 O values of rainfall, vadose percolation water, and speleothem calcite was investigated in a cave at Waitomo. Water samples were obtained approximately monthly for two years from a storage rain gauge on the surface and from stored seepage from three stalactites underground. Rain water δ 18 O SMOW values varied considerably throughout the observation period, with a precipitation-weighted mean of -5.3 permille. Seasonal variability was evident, with winter values being more negative than summer values. Cave seepage waters had a mean of about -5 permille and showed very little variability and no discernible annual variation. This is explained by thorough mixing in the soil and subcutaneous zone stores. Given the average cave temperature (12.8 degrees C) and the δ 18 O SMOW value determined for seepage water, the δ 18 O PDB value of calcite that is actively depositing in isotopic equilibrium on speleothems at Waitomo should fall in the range of -4.1 to -4.6 permille. Observed delta-values of modern speleothem calcites overlap the positive end of this range of theoretical values, indicating that some growing speleothems are not in isotopic equilibrium with seepage waters, but are experiencing either evaporation or kinetic fractionation. (author). 32 refs., 8 figs

  13. Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion-adsorption model of uranium uptake.

    Science.gov (United States)

    Cid, A S; Anjos, R M; Zamboni, C B; Cardoso, R; Muniz, M; Corona, A; Valladares, D L; Kovacs, L; Macario, K; Perea, D; Goso, C; Velasco, H

    2014-10-01

    Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion-adsorption (RDA) model is described. Unlike the classic diffusion-adsorption (D-A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ∪-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10(-12) cm(2)s(-1). Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Dating Violence

    Science.gov (United States)

    ... for Teens / Dating Violence Bulletins for Teens: Dating Violence What is it? If you are a victim ... often. If You Are a Victim of Dating Violence, You Might… Think it's your fault. Feel angry, ...

  15. Changes in seasonal climate patterns from 34-4 ka in a Soreq Cave (Israel) speleothem: Sub-annual resolution by ion microprobe and CLFM

    Science.gov (United States)

    Orland, I. J.; Bar-Matthews, M.; Kita, N.; Ayalon, A.; Valley, J. W.

    2009-12-01

    Speleothems provide an important proxy-record of paleoclimate. Isotopic data from calcite-dominated cave formations have been used to identify changes in annual rainfall, monsoon strength, telecommunication of Northern Hemisphere climate aberrations, changes in vegetation cover, and other region-specific paleoclimate time-series over annual to millennial timescales. As more research is devoted to understanding abrupt climate change events, there is a need to develop high-temporal-resolution records from continental regions. However, in most isotopic studies, seasonality information is lost due to technical limitations. This study focuses on a speleothem from the semi-arid Eastern Mediterranean region (Soreq Cave, Israel) where prior research shows that conventional drill-sampling methods permit a temporal resolution of ~10-50 years in speleothem paleoclimate records. The WiscSIMS lab has developed analytical protocols for ion microprobe analysis that yield a precision of ~0.3‰ (2 s.d.) in δ18O from 10 μm-diameter spots, which permit multiple analyses/year in many speleothems. Orland et al. (2009, Quat. Res.) establish the methodology for the current study by identifying seasonal variability using a combination of confocal laser fluorescent microscopy (CLFM) and ion microprobe analysis in a younger (~2-1 ka) Soreq speleothem that has a consistent bright-grading-to-dark fluorescence pattern within each annual band. Further, Orland et al. define a quantitative measure of seasonality, Δ18O, that measures the difference in δ18O between bright and dark fluorescent portions of individual annual growth bands [Δ18O = δ18Odark - δ18Obright]. Smaller values of Δ18O are interpreted to be caused by dry years. The current study employs the aforementioned methods to examine seasonality trends in a sample that covers a much longer time period. We report δ18O from >1000 spots across a radial traverse of Soreq Cave sample 2N matched to imaging of annual growth bands by

  16. Inter-annual precipitation variabiity inferred from late Holocene speleothem records from Fiji: implications for SPCZ localisation and ENSO behaviour

    Science.gov (United States)

    Mattey, D.; Stephens, M.; Hoffmann, D.; Brett, M.

    2015-12-01

    The modern tropical Fiji climate is characterised by seasonal rainfall controlled by the position of the South Pacific Convergence Zone (SPCZ). Interannual rainfall is strongly modulated on decadal timescales by ENSO with higher rainfall associated with La Nina events. Voli Voli cave near Sigatoga (Viti Levu) is a stream passage that has been monitored since 2009. A U-Th dated laminated speleothem spans a 1500 year interval across the transition from the Medieval Warm Period into the Little Ice Age marked by a fabric change from finely laminated calcite with thin clay layers, to white well-laminated calcite. The older record is characterised by rising δ13C values followed by a rapid decrease in δ13C around 1200 AD. Evidence from cave monitoring shows that cave air CO2 levels are strongly seasonal as a result of greater ventilation by winter trade winds and high resolution δ13C record shows regularly spaced peaks correlated with paired laminae and cycles in P and S which provide annual markers driven by rainfall and seasonal ventilation. δ18O values remain relatively unchanged throughout the record but micromilling at sub-annual resolution reveals systematic cycles in δ18O that span groups of paired laminae with an inferred periodicity of 3-7 years i.e. a similar frequency to modern ENSO. The presence of these sub-decadal cycles in δ18O may be a result of a combination of factors. The amplitude of 2-3‰ would be equivalent to an amount-effect related change in annual precipitation of around 50% but an additional smoothing process, perhaps a result of aquifer storage, is required to attenuate interannual variance in precipitation. The Voli Voli record provides evidence of an underlying climatic change to more frequent La Niña conditions from 1200 AD and may be associated with increased conflict, shifts in settlements and changes in subsistence strategies on the island. Coeval speleothem isotope records from tropical Pacific Islands provide a provide a

  17. Simulated oxygen isotopes in cave drip water and speleothem calcite in European caves

    Directory of Open Access Journals (Sweden)

    A. Wackerbarth

    2012-11-01

    Full Text Available Interpreting stable oxygen isotope (δ18O records from stalagmites is still one of the complex tasks in speleothem research. Here, we present a novel model-based approach, where we force a model describing the processes and modifications of δ18O from rain water to speleothem calcite (Oxygen isotope Drip water and Stalagmite Model – ODSM with the results of a state-of-the-art atmospheric general circulation model enhanced by explicit isotope diagnostics (ECHAM5-wiso. The approach is neither climate nor cave-specific and allows an integrated assessment of the influence of different varying climate variables, e.g. temperature and precipitation amount, on the isotopic composition of drip water and speleothem calcite.

    First, we apply and evaluate this new approach under present-day climate conditions using observational data from seven caves from different geographical regions in Europe. Each of these caves provides measured δ18O values of drip water and speleothem calcite to which we compare our simulated isotope values. For six of the seven caves modeled δ18O values of drip water and speleothem calcite are in good agreement with observed values. The mismatch of the remaining caves might be caused by the complexity of the cave system, beyond the parameterizations included in our cave model.

    We then examine the response of the cave system to mid-Holocene (6000 yr before present, 6 ka climate conditions by forcing the ODSM with ECHAM5-wiso results from 6 ka simulations. For a set of twelve European caves, we compare the modeled mid-Holocene-to-modern difference in speleothem calcite δ18O to available measurements. We show that the general European changes are simulated well. However, local discrepancies are found, and might be explained either by a too low model resolution, complex local soil-atmosphere interactions affecting evapotranspiration or by cave specific factors

  18. Calibrating multiple isotopic proxies in a modern aragonite speleothem from northeast India

    Science.gov (United States)

    Ronay, E.; Oster, J. L.; Sharp, W. D.; Marks, N.; Erhardt, A.; Breitenbach, S. F. M.

    2017-12-01

    Uranium, strontium, and calcium isotope ratios in calcite speleothems are used as proxies for water-soil-rock interactions and prior calcite precipitation, and thus provide information about effective rainfall amount variations, primarily in semi-arid or highly seasonal regions. However, less is known about how these proxies function in humid regions and in aragonite speleothems. In this study, we use meteorological data to calibrate (234U/238U)i and 87Sr/86Sr in a modern aragonite speleothem from northeast India, the rainiest place on Earth, to determine how these proxies reflect effective monsoon rainfall amount. MAW-0201 is an annually laminated aragonite stalagmite that grew from 1960-2013 in Mawmluh Cave, Meghalaya, India. Rainfall here is extremely seasonal due to the Indian Summer Monsoon (ISM), which brings several meters of rain to the region each summer, but with inter-annual variability in total rainfall. The δ18O in Mawmluh dripwater and speleothems reflects moisture source and transport, rather than rainfall amount. Variations in Mg, U, and Ba concentrations in MAW-0201 show seasonal and multi-annual variability. U and Mg are closely correlated, but multi-year periods show significant anti-correlation. The Mg and U distribution coefficients in calcite and aragonite indicate correlated periods are times of prior calcite precipitation (PCP) and anti-correlated periods are times of prior aragonite precipitation (PAP) in the epikarst. We use δ44/40Ca to test this hypothesis, as Ca isotopes fractionate differently during calcite and aragonite precipitation and speleothem δ44/40Ca will record unique PAP and PCP fingerprints. We propose such shifts from PCP to PAP reflect hydrologic variability and/or flow path changes, which provide a useful tool for understanding epikarst hydrology but may also be a complicating factor in speleothem-based paleoclimate interpretations. Preliminary (234U/238U)i (always <1) and 87Sr/86Sr spanning 1991-2009 each show

  19. The last glacial inception in continental northwestern Europe: characterization and timing of the Late Eemian Aridity Pulse (LEAP) recorded in multiple Belgian speleothems.

    Science.gov (United States)

    Vansteenberge, Stef; Verheyden, Sophie; Quinif, Yves; Genty, Dominique; Blamart, Dominique; Deprez, Maxim; Van Stappen, Jeroen; Cnudde, Veerle; Cheng, Hai; Edwards, R. Lawrence; Claeys, Philippe

    2017-04-01

    Interglacial-glacial transitions represent important turnovers in the climate system. In contrast with glacial terminations, they are described as a more gradual cooling. So far, the last interglacial has yielded a wealth of knowledge regarding climate dynamics during past warm periods. On top of the assumed gradual temperature drop starting at 119 ka, evidence for the presence of a drastic drying/cooling event in northern Europe has been observed. In lake records from Germany, a distinct shift in pollen assembly at 117.5 ka is interpreted as the consequence of a short dry event lasting 470 years, defined as the Late Eemian Aridity Pulse (LEAP, Sirocko et al., 2005). In a Belgian stalagmite from Han-sur-Lesse Cave, the LEAP is characterized by a 5‰ increase in δ13C occurring in just 200 years. The δ13C enrichment is dated at 117.5 ka and associated with a vegetation change above the cave, induced by a drying and/or cooling event (Vansteenberge et al., 2016). Also, within North Atlantic sediment cores, an increase in ice rafted debris was linked to the occurrence of a colder period at 117 ka (Irvali et al., 2016). Its coevality with the LEAP indicates a likely more regional extent than previously thought. Up to now, no independent chronology exists and little is known about the continental climatic expression of the LEAP. This study aims at 1) constructing an improved and independent chronology for the LEAP event, 2) characterizing this event in terms of its climatic expression and 3) placing the LEAP within the context of an interglacial-glacial transition. For this, two additional speleothems (Han-8, RSM-17) from two different Belgian caves (Han-sur-Lesse, Remouchamps) are added to the existing Han-9 dataset. Exceptionally high growth rates (0.5 mm yr-1) and a presumed annual layering of the RSM-17 sample enable an annual to decadal resolution to investigate the LEAP. U-Th age models covering the glacial inception are constructed with 25 dates on the three

  20. Dating Violence

    Science.gov (United States)

    Stader, David L.

    2011-01-01

    Dating violence is a form of student-on-student victimization and is a serious school safety issue. Research indicates that at a minimum, 10 percent of high school students are victims of dating violence in one form or another. Among female high school students that date, some data indicate that as many as 30 percent may be victims of dating…

  1. U–Pb, Rb–Sr, and U-series isotope geochemistry of rocks and fracture minerals from the Chalk River Laboratories site, Grenville Province, Ontario, Canada

    International Nuclear Information System (INIS)

    Neymark, L.A.; Peterman, Z.E.; Moscati, R.J.; Thivierge, R.H.

    2013-01-01

    Highlights: • AECL evaluates Chalk River Laboratories site as potential nuclear waste repository. • Isotope-geochemical data for rocks and fracture minerals at CRL site are reported. • Zircons from gneiss and granite yielded U–Pb ages of 1472 ± 14 and 1045 ± 6 Ma. • WR Rb–Sr and Pb–Pb systems do not show substantial large-scale isotopic mobility. • U-series and REE data do not support oxidizing conditions at depth in the past 1 Ma. - Abstract: As part of the Geologic Waste Management Facility feasibility study, Atomic Energy of Canada Ltd. (AECL) is evaluating the suitability of the Chalk River Laboratories (CRL) site in Ontario, situated in crystalline rock of the southwestern Grenville Province, for the possible development of an underground repository for low- and intermediate-level nuclear waste. This paper presents petrographic and trace element analyses, U–Pb zircon dating results, and Rb–Sr, U–Pb and U-series isotopic analyses of gneissic drill core samples from the deep CRG-series characterization boreholes at the CRL site. The main rock types intersected in the boreholes include hornblende–biotite (±pyroxene) gneisses of granitic to granodioritic composition, leucocratic granitic gneisses with sparse mafic minerals, and garnet-bearing gneisses with variable amounts of biotite and/or hornblende. The trace element data for whole-rock samples plot in the fields of within-plate, syn-collision, and volcanic arc-type granites in discrimination diagrams used for the tectonic interpretation of granitic rocks. Zircons separated from biotite gneiss and metagranite samples yielded SHRIMP-RG U–Pb ages of 1472 ± 14 (2σ) and 1045 ± 6 Ma, respectively, in very good agreement with widespread Early Mesoproterozoic plutonic ages and Ottawan orogeny ages in the Central Gneiss Belt. The Rb–Sr, U–Pb, and Pb–Pb whole-rock errorchron apparent ages of most of the CRL gneiss samples are consistent with zircon U–Pb age and do not indicate

  2. Coupling data from U-series and 10Be CRN to evaluate soil steady-state in the Betic Cordillera

    Science.gov (United States)

    Schoonejans, Jerome; Vanacker, Veerle; Opfergelt, Sophie; Granet, Mathieu; Chabaux, François

    2015-04-01

    The regolith mantel is produced by weathering of bedrock through physical and biochemical processes. At the same time, the upper part of the regolith is eroded by gravity mass movements, water and wind erosion. Feedback's between production and erosion of soil material are important for soil development, and are essential to reach long-term steady-state in soil chemical and physical properties. Nowadays, long-term denudation rates of regolith can be quantified by using in-situ cosmogenic nuclides (CRN). If the soil thickness remains constant over sufficiently long time, soil production rates can be determined. However, the a priori assumption of long-term steady-state can be questionable in highly dynamic environments. In this study, we present analytical data from two independent isotopic techniques, in-situ cosmogenic nuclides and Uranium series disequilibrium. The disequilibrium of Uranium isotopes (238U, 234U, 230Th, 226Ra) is an alternative method that allows assessing soil formation rates through isotopic analysis of weathering products. Nine soil profiles were sampled in three different mountain ranges of the Betic Cordillera (SE Spain): Sierra Estancias, Filabres, Cabrera. All soils overly fractured mica schist and are very thin (< 60cm). In each soil profile, we sampled 4 to 6 depth slices in the soil profile, the soil-bedrock interface and (weathered) bedrock. Three of the nine soil profiles were sampled for U-series isotope measurements at EOST (University of Strasbourg). The surface denudation rates (CRN) are about the same in the Sierra Estancias and Filabres (26 ± 10 mm/ky) and increase up to 103 ± 47 mm/ky in the Sierra Cabrera. The spatial variation in soil denudation rates is in agreement with the variation in catchment-wide denudation rates presented by Bellin et al. (2014) which present the highest rates in the Sierra Cabrera (104-246mm/kyr). Moreover it roughly coincides with the pattern of long-term exhumation of the Betic Cordillera. Results

  3. Diagenesis of a drapery speleothem from Castañar Cave: from dissolution to dolomitization

    Directory of Open Access Journals (Sweden)

    Martín-Pérez A.

    2012-07-01

    Full Text Available A drapery speleothem (DRA-1 from Castañar Cave in Spain was subjected to a detailed petrographical study in order to identify its primary and diagenetic features. The drapery’s present day characteristics are the result of the combined effects of the primary and diagenetic processes that DRA-1 underwent. Its primary minerals are calcite, aragonite and huntite. Calcite is the main constituent of the speleothem, whereas aragonite forms as frostwork over the calcite. Huntite is the main mineral of moonmilk which covers the tips of aragonite. These primary minerals have undergone a set of diagenetic processes, which include: 1 partial dissolution or corrosion that produces the formation of powdery matt-white coatings on the surface of the speleothem. These are seen under the microscope as dark and highly porous microcrystalline aggregates; 2 total dissolution produces pores of few cm2 in size; 3 calcitization and dolomitization of aragonite result in the thickening and lost of shine of the aragonite fibres. Microscopically, calcitization is seen as rhombohedral crystals which cover and replace aragonite forming mosaics that preserve relics of aragonite precursor. Dolomitization results in the formation of microcrystalline rounded aggregates over aragonite fibres. These aggregates are formed by dolomite crystals of around 1 μm size. The sequence of diagenetic processes follows two main pathways. Pathway 1 is driven by the increase of saturation degree and Mg/Ca ratio of the karstic waters and is visible in the NW side of the drapery. This sequence of processes includes: 1 aragonite and huntite primary precipitation and 2 dolomitization. Pathway 2 is driven by a decrease in the degree of saturation of calcite and aragonite and Mg/Ca ratio of the cave waters, and it is observed in the SE side of the drapery. The diagenetic processes of the second pathway include: 1 calcitization of aragonite; 2 incomplete dissolution (micritization of both

  4. Environmental control of U concentration and 234U/238U in speleothems at subannual resolution

    Science.gov (United States)

    Hu, C.; Henderson, G. M.

    2003-12-01

    Trace element and isotope variability in speleothems encodes a range of information about the past environment, although its interpretation is often problematic. U concentration and isotopes have frequently been analysed in speleothems in order to provide chronology, but their use as environmental proxies in their own right has not been comprehensively investigated. In this study, we have investigated the environmental controls of U in a stalagmite from the Central Yangtze Valley in China. This stalagmite grew rapidly throughout the Holocone and contains visible annual layers about 300microns thick. Analysis of a portion of the stalagmite corresponding to the 1970s by electron probe, LA-ICP-MS, and by physical subsampling indicate clear annual cycles in Sr/Ca, Mg/Ca, and Ba/Ca. The reasonably open cave structure and the correlation of Sr/Ca with Mg/Ca suggest that temperature exerts considerable control over these trace element variations. U/Ca also varies seasonally by up to 42 % and shows a clear anti-correlation with Mg/Ca (correlation coefficient -0.64). Based on the inverse relationship between U/Ca and temperature exhibited in other carbonates (e.g. corals) the speleothem U/Ca is suggested to be controlled primarily by temperature and may provide a paleo cave thermometer with less rainfall influence than Mg/Ca. Ongoing monitoring of the cave temperature and humidity will assess the robustness of this conclusion and the sensitivity of speleothem U/Ca to temperature. (234U/238U) in this stalagmite range from 1.733 to 1.872 during the Holocene. The U concentration is high enough (typically 0.48 ppm) and growth rate fast enough, that (234U/238U) can also be measured at a subannual resolution. The expected alpha-recoil control of excess 234U supply suggests that these measurements may provide a measure of the transit time of recharge waters to the stalagmite during the seasonal cycle. Such a proxy would enable deconvolution of temperature and recharge-rate control

  5. Regional influence of decadal to multidecadal Atlantic Oscillations during the last two millennia in Morocco, inferred from two high resolution δ18O speleothem records

    Science.gov (United States)

    Ait Brahim, Yassine; Sifeddine, Abdelfettah; Khodri, Myriam; Bouchaou, Lhoussaine; Cruz, Francisco W.; Pérez-Zanón, Núria; Wassenburg, Jasper A.; Cheng, Hai

    2017-04-01

    Climate projections predict substantial increase of extreme heats and drought occurrences during the coming decades in Morocco. It is however not clear what can be attributed to natural climate variability and to anthropogenic forcing, as hydroclimate variations observed in areas such as Morocco are highly influenced by the Atlantic climate modes. Since observational data sets are too short to resolve properly natural modes of variability acting on decadal to multidecadal timescales, high resolution paleoclimate reconstructions are the only alternative to reconstruct climate variability in the remote past. Herein, we present two high resolution and well dated speleothems oxygen isotope (δ18O) records sampled from Chaara and Ifoulki caves (located in Northeastern and Southwestern Morocco respectively) to investigate hydroclimate variations during the last 2000 years. Our results are supported by a monitoring network of δ18O in precipitation from 17 stations in Morocco. The new paleoclimate records are discussed in the light of existing continental and marine paleoclimate proxies in Morocco to identify significant correlations at various lead times with the main reconstructed oceanic and atmospheric variability modes and possible climate teleconnections that have potentially influenced the climate during the last two millennia in Morocco. The results reveal substantial decadal to multidecadal swings between dry and humid periods, consistent with regional paleorecords. Evidence of dry conditions exist during the Medieval Climate Anomaly (MCA) period and the Climate Warm Period (CWP) and humid conditions during the Little Ice Age (LIA) period. Statistical analyses suggest that the climate of southwestern Morocco remained under the combined influence of both the Atlantic Multidecadal Oscillation (AMO) and the North Atlantic Oscillation (NAO) over the last two millennia. Interestingly, the generally warmer MCA and colder LIA at longer multidecadal timescales probably

  6. Microbial Diversity and Mineralogical-Mechanical Properties of Calcitic Cave Speleothems in Natural and in Vitro Biomineralization Conditions

    Directory of Open Access Journals (Sweden)

    Navdeep K. Dhami

    2018-02-01

    Full Text Available Natural mineral formations are a window into important processes leading to carbon storage and mineralized carbonate structures formed through abiotic and biotic processes. In the current study, we made an attempt to undertake a comprehensive approach to characterize the mineralogical, mechanical, and microbial properties of different kinds of speleothems from karstic caves; with an aim to understand the bio-geo-chemical processes in speleothem structures and their impact on nanomechanical properties. We also investigated the biomineralization abilities of speleothem surface associated microbial communities in vitro. Mineralogical profiling using techniques such as X-ray powder Diffraction (XRD and Tescan Integrated Mineral Analyzer (TIMA demonstrated that calcite was the dominant mineral in the majority of speleothems with Energy Dispersive X-ray Analysis (EDS indicating a few variations in the elemental components. Differing proportions of polymorphs of calcium carbonate such as aragonite and vaterite were also recorded. Significant variations in trace metal content were recorded through Inductively Coupled Plasma Mass Spectrometer (ICP-MS. Scanning Electron Microscopy (SEM analysis revealed differences in morphological features of the crystals which varied from triangular prismatic shapes to etched spiky forms. Microbial imprints and associations were seen in a few sections. Analysis of the associated microbial diversity showed significant differences between various speleothems at Phylum level; although Proteobacteria and Actinobacteria were found to be the predominant groups. Genus level microbial associations showed a relationship with the geochemistry, mineralogical composition, and metal content of the speleothems. The assessment of nanomechanical properties measured by Nanoindentation revealed that the speleothems with a dominance of calcite were stronger than the speleothems with mixed calcium carbonate polymorphs and silica content

  7. Paleoclimate in continental northwestern Europe during the Eemian and early Weichselian (125-97 ka): insights from a Belgian speleothem

    Science.gov (United States)

    Vansteenberge, Stef; Verheyden, Sophie; Cheng, Hai; Edwards, R. Lawrence; Keppens, Eddy; Claeys, Philippe

    2016-07-01

    The last interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of last interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alps, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European last interglacial continental records is essential, and speleothems, because of their ability to obtain excellent chronologies, can provide a major contribution. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse Cave in Belgium. Han-9 formed between 125.3 and ˜ 97 ka, with interruptions of growth occurring at 117.3-112.9 and 106.6-103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) composition. The speleothem started growing relatively late within the last interglacial, at 125.3 ka, as other European continental archives suggest that Eemian optimum conditions were already present during that time. It appears that the initiation of Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka; however, at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the Marine Isotope Stage (MIS) 5e-5d transition. At 117.5 ka, drastic vegetation changes are recorded by Han-9 δ13C immediately followed by a cessation of speleothem growth at 117.3 ka, suggesting a transition to significantly dryer conditions. The Han-9 record covering the early Weichselian displays larger amplitudes in both isotope proxies and changes in stalagmite

  8. Hydroclimate of the Last Glacial Maximum and deglaciation in southern Australia's arid margin interpreted from speleothem records (23–15 ka

    Directory of Open Access Journals (Sweden)

    P. C. Treble

    2017-06-01

    Full Text Available Terrestrial data spanning the Last Glacial Maximum (LGM and deglaciation from the southern Australian region are sparse and limited to discontinuous sedimentological and geomorphological records with relatively large chronological uncertainties. This dearth of records has hindered a critical assessment of the role of the Southern Hemisphere mid-latitude westerly winds on the region's climate during this time period. In this study, two precisely dated speleothem records for Mairs Cave, Flinders Ranges, are presented, providing for the first time a detailed terrestrial hydroclimatic record for the southern Australian drylands during 23–15 ka. Recharge to Mairs Cave is interpreted from the speleothem record by the activation of growth, physical flood layering, and δ18O and δ13C minima. Periods of lowered recharge are indicated by 18O and 13C enrichment, primarily affecting δ18O, argued to be driven by evaporation of shallow soil/epikarst water in this water-limited environment. A hydrological driver is supported by calcite fabric changes. These include the presence of laminae, visible organic colloids, and occasional dissolution features, related to recharge, as well as the presence of sediment bands representing cave floor flooding. A shift to slower-growing, more compact calcite and an absence of lamination is interpreted to represent reduced recharge. The Mairs Cave record indicates that the Flinders Ranges were relatively wet during the LGM and early deglaciation, particularly over the interval 18.9–15.8 ka. This wetter phase ended abruptly with a shift to drier conditions at 15.8 ka. These findings are in agreement with the geomorphic archives for this region, as well as the timing of events in records from the broader Australasian region. The recharge phases identified in the Mairs Cave record are correlated with, but antiphase to, the position of the westerly winds interpreted from marine core MD03-2611, located 550 km south

  9. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2009-01-01

    The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materals in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs.

  10. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2008-01-01

    The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materals in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs

  11. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2012-01-01

    The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materials in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs.

  12. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2009-01-01

    The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materals in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs

  13. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2013-01-01

    The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materials in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs.

  14. Element enrichment and U-series isotopic characteristics of the hydrothermal sulfides at Jade site in the Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127°04.5′E, 27°15′N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the 210Pb radioactivity ratios and 210Pb/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the 210Pb/Pb ratios of hydrothermal sulfide samples (3.99×10-5-5.42×10?5), their U isotopic composition (238U content 1.15-2.53 ppm, 238U activity 1.07-1.87 dpm/g, 234U activity 1.15-2.09 dpm/g and 234U/238U ratio 1.07-1.14) and their 232Th and 230Th contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.

  15. Insights into changes in precipitation patterns in Brazil from oxygen isotope ratios on speleothems

    Science.gov (United States)

    Cruz, F.; Mathias, V.; Stephen, B. J.; Wang, X.; Cheng, H.; Werner, M.; Edwards, R. L.; Karmann, I.; Auler, A. S.

    2008-12-01

    Variations in tropical precipitation on millennial and orbital time scales can reflect a Hadley-cell-related anti- phasing between the Northern and Southern hemispheres due to the influence of insolation on the global summer monsoons. A new δ18O speleothem record from northeastern Brazil shows that insolation- driven changes in monsoon intensity are capable of producing a similar, zonally oriented anti-phasing within the same hemisphere. Comparison of our speleothem record with other precipitation-sensitive proxies from the central Andes and southeastern Brazil shows that precipitation in Northeastern Brazil has been out of phase with insolation and rainfall in the rest of tropical South America south of the equator since the Last Glacial Maximum. Northeastern Brazil experienced humid conditions when summer insolation was reduced and arid conditions when insolation was high. While previous interpretations of past climate change in NE South America have commonly invoked meridional displacements in ITCZ location as the main mechanism for changes in precipitation on millennial time scales, our results suggest that remote monsoon forcing is responsible for much of the observed precipitation changes on orbital time scales during the Holocene. These results demonstrate that orbitally driven out-of-phase relationships in precipitation are not limited to interhemispheric anti-phasing as demonstrated previously, but may well occur within the same hemisphere. Speleothem records also indicate contrasting climatic conditions around the Last Glacial Maximum in Brazil, characterized by marked dry and wet climates in the Nordeste and in southeastern Brazil, respectively. It is likely, however, that these regional differences primarily reflect more distant extratropical teleconnections from the Atlantic Ocean and high northern latitude changes during glacial conditions.

  16. Holocene precipitation changes in the deep tropics recorded by Speleothems (Invited)

    Science.gov (United States)

    Wang, X.; Auler, A. S.; Edwards, R.; Kong, X.; Cheng, H.; Cruz, F. W.; Wang, Y.; Broecker, W. S.

    2010-12-01

    We have obtained a high-resolution oxygen isotope (δ18O) record of cave calcite from Paraiso Cave, eastern Amazon, which covers most of the Holocene. Its chronology was determined by U-Th ages from three column-shaped stalagmites. Their δ18O profiles replicate among their contemporaneous growth periods. Therefore, the samples were likely precipitated under equilibrium conditions and their oxygen isotopic variations are primarily caused by climate change. We find that the δ18O decreases steadily from ~11.0 to 5.0 thousand years ago, with a growth gap between ~8.4 to 6.3 thousand years ago, and then gradually increases until the present. The large amplitude of the δ18O change (up to 4 per mil) suggests that the variation in δ18O value is dominated by meteoric precipitation change at this equatorial site. In order to investigate the interactions between the Intertropical Convergence Zone (ITCZ), monsoons and El Niño-Southern Oscillation (ENSO) activity during the Holocene, we compare the Paraiso record to speleothem records from other locations in the deep tropics, namely, cave sites from Flores, Borneo and Peru. We find that all these speleothem records are consistent, with a progressive δ18O decrease (rainfall increase) during the early Holocene, probably in response to the southward retreat of the ITCZ from its northernmost location in the early Holocene. This is evident from the strong anti-correlation between the speleothem monsoonal records from China and southern Brazil. However, our record is distinct from the others during the last 4 thousand years, when it switches to a continuous δ18O increase (rainfall decrease) trend, while the others flatten out. We propose that, during the late Holocene, the strengthened South American Summer Monsoon may override the ENSO influence and cause the discrepancy in precipitation between eastern Amazon and other deep tropical cave sites.

  17. Historical droughts in northern Vietnam captured by variability in speleothem δ18O

    Science.gov (United States)

    Hardt, B. F.; McGee, D.; Burns, S. J.; Hieu, N.; Hieu, D. T.

    2015-12-01

    Speleothem records overlapping with the historical period offer valuable comparisons of documentary evidence with speleothem proxy data. These records provide opportunities to 'ground-truth' the paleo-record, fill in gaps in the historical record, and more confidently extent the paleo-record into deeper time. Here we present isotopic results from a stalagmite collected in northern Vietnam spanning 1200 to 1950 CE, a period with a rich historical record in Vietnam. This sample adds significantly to the relatively sparse paleoclimate record from Southeast Asia. The record includes several multi-decadal positive excursions of ≥1 per mille in calcite δ18O. A preliminary age model, based on six U/Th ages, suggests possible correspondence to noted droughts from the historical record, including the Angkor Droughts, the Ming Dynasty Drought, the Strange Parallels Drought, and the Victorian Holocaust Drought. As modeling studies indicate a strong correlation between rainfall δ18O and both the intensity of summer monsoon winds and summer rainfall over northern Vietnam (e.g., Liu et al., 2014), these excursions are consistent with a decrease in regional precipitation. The Vietnam record shows an overall negative trend during the Little Ice Age. The study site is located well south of the westerly wind belt, ruling out a shift between monsoonal and mid-latitude circulation systems as a likely explanation for the northern Vietnam record. We explore the correspondence between our record and other proxy data from Southeast Asia and suggest possible implications of the differences between Vietnamese and Chinese speleothem records during the Little Ice Age. References cited: Liu Z., Wen X., Brady E. C., Otto-Bliesner B., Yu G., Lu H., Cheng H., Wang Y., Zheng W., Ding Y., Edwards R. L., Cheng J., Liu W. and Yang H. (2014) Chinese cave records and the East Asia Summer Monsoon. Quaternary Science Reviews 83, 115-128.

  18. Are U-Series Disequilibria Transparent to Crustal Processing of Magma? A Case Study at Bezymianny and Klyuchevskoy Volcanoes, Kamchatka, Russia

    Science.gov (United States)

    Kayzar, T. M.; Nelson, B. K.; Bachmann, O.; Portnyagin, M.; Ponomareva, V.

    2010-12-01

    Disequilibria in the short-lived uranium-series isotopic system can provide timescales of magma production, modification and transport in all tectonic settings. In volcanic arcs, the field has converged on the concept that (238U/230Th) and (226Ra/230Th) activities greater than one are a result of fluid fluxing from the slab to mantle wedge, and that the preservation of (226Ra/230Th) disequilibria requires rapid transport of melts from the mantle wedge to the surface (226Ra returns to equilibrium with 230Th in ~8000 years). The need for rapid transport coupled with the incompatibility of U-series elements suggest that U-series fractionation is not measurably affected by crustal processes. However, some well-studied arc systems, including the very productive Central Kamchatka Depression (CKD) of the Kamchatkan volcanic arc, show U-series data that are in conflict with this commonly accepted model. Our study focuses on two neighboring volcanic systems, Bezymianny and Klyuchevskoy volcanoes in the CKD. Separated by ~10km, these two systems are thought to share the same mantle source. Klyuchevskoy has primitive compositions (51-56 wt%) while Bezymianny erupts more differentiated andesites (57-63 wt% SiO2); therefore, by examining the U-series signals in these two systems it is possible to decouple a primary signal from one having undergone crustal processing. We record whole rock (238U/230Th) values for Bezymianny ranging from 0.94 to 0.96 in modern eruptive products, while (226Ra/230Th) are >1. We also observe a similar signal in older (212-6791BP) tephra deposits from Klyuchevskoy, measuring (238U/230Th) of 0.92-0.99 (unpublished data, collaborative research with the KALMAR project). (238U/230Th) local bulk rock or partial melts to fractionate U, Th, and Ra from one another. In particular, we focus on minor mineral phases, such as apatite and magnetite, which are present during early stages of differentiation (andesites) and may fractionate U from Th. We measure U and

  19. High resolution geochemical proxy record of the last 600yr in a speleothem from the northwest Iberian Peninsula

    Science.gov (United States)

    Iglesias González, Miguel; Pisonero, Jorge; Cheng, Hai; Edwards, R. Lawrence; Stoll, Heather

    2017-04-01

    In meteorology and climatology, the instrumental period is the period where we have measured directly by instrumentation, different meteorological data along the surface which allow us to determinate the evolution of the climate during the last 150 years over the world. At the beginning, the density of this data were very low, so we have to wait until the last 75-100 years to have a good network in most of the parts of the surface. This time period is very small if we want to analyze the relationship between geochemical and instrumental variability in any speleothem. So a very high resolution data is needed to determinate the connection between both of them in the instrumental period, to try to determinate de evolution of climate in the last 600 years. Here we present a high resolution speleothem record from a cave located in the middle of the Cantabrian Mountains without any anthropologic influence and with no CO2 seasonal variability. This 600yr stalagmite, dated with U/Th method with a growth rate from 100 to 200 micrometers/yr calculated with Bchron model, provide us accurate information of the climate conditions near the cave. Trace elements are analyzed at 8 micrometers intervals by Laser Ablation ICP-MS which resolves even monthly resolution during the last 600 years with special attention with Sr, Mg, Al and Si. This data, without seasonal variability and with the presence of a river inside the cave, give us very valuable information about the extreme flood events inside the cave during the whole period, which is related with the precipitations and the snow fusion events outside the cave. We identify more extremely flood events during the Little Ice Age than in the last 100yr. As well, we have trace elements data with spatial resolution of 0.2mm analyzed with ICP-AES which allow us to compare the geochemical variability with both technics. We also analyze stable isotope d13C and d18O with a spatial resolution of 0.2mm, so we are able to identify variations

  20. Radiometric dating

    International Nuclear Information System (INIS)

    Das, N.R.

    2017-01-01

    Since the discovery of natural radioactivity in uranium, in the last decade of the nineteenth century, the nuclear property of radioactive decay of radionuclides at immutable rates has been effectively utilized in dating of varieties of naturally occurring geological matrices and the organisms which constantly replenish their "1"4C supply through respiration when alive on earth. During the period, applications of radiometric dating techniques have been extensively diversified and have enabled the geologists to indicate the absolute time scales of geological formations and the evolution of the solar system, the earth, meteorites, lunar rocks, etc. and the archaeologists to record the facts of history of several important events like dinosaur era, Iceman, the Shroud in Turin and many other ancient artefacts. In the development of dating methods, varieties of naturally occurring radio-isotopic systems with favorable half-lives ranging from about 10 years to over 100 billion years have been used as radiometric clocks. (author)

  1. Speleothems from Mawsmai and Krem Phyllut caves, Meghalaya, India: some evidences on biogenic activities

    Science.gov (United States)

    Baskar, Sushmitha; Baskar, R.; Lee, Natuschka; Theophilus, P. K.

    2009-05-01

    The Mawsmai cave and Krem Phyllut caves, East Khasi hills, Meghalaya, India has so far not yet attracted the attention of geomicrobiologists. Observations and hypotheses on the possible influence of identified microorganisms for speleothem formations in Meghalaya are reported for the first time. XRD studies identified calcite in speleothems and gypsum in cave wall deposits as the dominant minerals. SEM-EDAX showed interesting microfabric features showing strong resemblance with fossilised bacteria, calcified filaments, needle calcite and numerous nano scale calcite crystals, highly weathered and disintegrated crystals of calcite, that point towards a significant microbial influence in its genesis. Thin section petrography showed laminated stromatolitic features. The microorganisms identified by conventional isolation and further evaluation of isolates by molecular techniques include Bacillus cereus, Bacillus mycoides, Bacillus licheniformis, Micrococcus luteus, and Actinomycetes. Microscopic observations also showed unidentifiable cocci and four unidentifiable strains of CaSO4 (gypsum) precipitating bacteria. Experimental studies confirmed that these bacteria are able to precipitate calcium minerals (calcite, gypsum, minor amounts of dolomite) in the laboratory. These results allow us to postulate that species like these may contribute to active biogenic influence in the cave formations at Meghalaya.

  2. 16,000 Years of Tropical Eastern Ocean Climate Variability Recorded in a Speleothem From Sumatra, Indonesia

    Science.gov (United States)

    Wurtzel, J. B.; Abram, N.; Hantoro, W. S.; Rifai, H.; Hellstrom, J. C.; Heslop, D.; Troitzsch, U.; Eggins, S.

    2015-12-01

    Holocene climate variability in the Indo-Pacific has largely been inferred from sediment cores primarily from the central and eastern Warm Pool region. A limited number of speleothem oxygen-isotope records have provided decadally-resolved time-series of past rainfall variability over the central Indo-Pacific Warm Pool region, however no records currently exist for the Indian Ocean sector of the IPWP. Here we present the first continuous, high-resolution (~15year) speleothem record from the eastern tropical Indian Ocean, collected from central western Sumatra, Indonesia. Petrographic and geochemical analysis reveals that the sample is primarily composed of aragonite but is punctuated by intervals of primary calcite growth. In addition to Raman spectroscopy, trace element analysis by laser ablation ICP-MS reveals strongly antiphased behaviour between magnesium and strontium, attributed to the strong preference of those elements for the calcite and aragonite lattices, respectively. This relationship is utilized to develop a quantitative correction for the stable isotope fractionation offset between the two calcium carbonate polymorphs identified in the speleothem. The corrected oxygen isotope record shows a rapid transition from drier conditions during the Younger Dryas (YD) into a wetter Holocene, similar in timing and pattern to that recorded in Dongge Cave, China. This is strikingly different from other IPWP speleothem records, which show no YD or a wetter YD, suggesting that different mechanisms may be controlling rainfall amount in the eastern tropical Indian Ocean. These disparate responses are further explored through proxy-model comparison.

  3. Southern Arizona hydroclimate over the last 3000 years: a comparison of speleothem elemental data and climate model simulations

    Science.gov (United States)

    King, J.; Harrington, M. D.; Cole, J. E.; Drysdale, R.; Woodhead, J. D.; Fasullo, J.; Stevenson, S.; Otto-Bliesner, B. L.; Overpeck, J. T.; Edwards, R. L.; Henderson, G. M.

    2017-12-01

    Understanding long-term hydroclimate is particularly important in semiarid regions where prolonged droughts may be exacerbated by a warming climate. In many regions, speleothem trace elements correlate with regional wet and dry climate signals. In the drought-prone Southwestern US (SW), wet and dry episodes are strongly influenced by seasonal changes in atmospheric circulation and teleconnections to remote forcing. Here, we address the need for seasonal moisture reconstructions using paleoclimate and climate model approaches. First, we present a high-resolution (sub-annual) record of speleothem trace elements spanning the last 3000 years from Fort Huachuca Cave, AZ, to investigate the variability of regional seasonal precipitation and sustained regional droughts. In a principal component (PC) analysis of the speleothem, trace elements associated with wet (Sr, Ba) and dry (P, Y, Zn) episodes load strongly and inversely, and the associated PC signals correlate with local gridded precipitation data over the last 50 years (R > 0.6, p external forcings, including volcanic eruptions, in both the speleothem record and the Community Earth System Model's Last Millennium Ensemble (CESM-LME). Notably, ENSO and volcanic forcing have a discernable effect on SW seasonal precipitation in model simulations, particularly when the two processes combine to shift the position of the ITCZ. This integrated analysis of paleodata with climate model results will help us identify and explain discrepancies between these information sources and improve stakeholders' ability to anticipate and prepare for future drought.

  4. New on-line method for water isotope analysis of speleothem fluid inclusions using laser absorption spectroscopy (WS-CRDS)

    Science.gov (United States)

    Affolter, S.; Fleitmann, D.; Leuenberger, M.

    2014-01-01

    A new online method to analyse water isotopes of speleothem fluid inclusions using a wavelength scanned cavity ring down spectroscopy (WS-CRDS) instrument is presented. This novel technique allows us to simultaneously measure hydrogen and oxygen isotopes for a released aliquot of water. To do so, we designed a new simple line that allows the on-line water extraction and isotope analysis of speleothem samples. The specificity of the method lies in the fact that fluid inclusions release is made on a standard water background, which mainly improves the δD reliability. To saturate the line, a peristaltic pump continuously injects standard water into the line that is permanently heated to 140 °C and flushed with dry nitrogen gas. This permits instantaneous and complete vaporisation of the standard water resulting in an artificial water background with well-known δD and δ18O values. The speleothem sample is placed into a copper tube, attached to the line and after system stabilisation is crushed using a simple hydraulic device to liberate speleothem fluid inclusions water. The released water is carried by the nitrogen/standard water gas stream directly to a Picarro L1102-i for isotope determination. To test the accuracy and reproducibility of the line and to measure standard water during speleothem measurements a syringe injection unit was added to the line. Peak evaluation is done similarly as in gas chromatography to obtain δD and δ18O isotopic composition of measured water aliquots. Precision is better than 1.5‰ for δD and 0.4‰ for δ18O for water measurement for an extended range (-210 to 0‰ for δD and -27 to 0‰ for δ18O) primarily dependent on the amount of water released from speleothem fluid inclusions and secondarily on the isotopic composition of the sample. The results show that WS-CRDS technology is suitable for speleothem fluid inclusion measurements and gives results that are comparable to Isotope Ratio Mass Spectrometry (IRMS) technique.

  5. New online method for water isotope analysis of speleothem fluid inclusions using laser absorption spectroscopy (WS-CRDS)

    Science.gov (United States)

    Affolter, S.; Fleitmann, D.; Leuenberger, M.

    2014-07-01

    A new online method to analyse water isotopes of speleothem fluid inclusions using a wavelength scanned cavity ring down spectroscopy (WS-CRDS) instrument is presented. This novel technique allows us simultaneously to measure hydrogen and oxygen isotopes for a released aliquot of water. To do so, we designed a new simple line that allows the online water extraction and isotope analysis of speleothem samples. The specificity of the method lies in the fact that fluid inclusions release is made on a standard water background, which mainly improves the δ D robustness. To saturate the line, a peristaltic pump continuously injects standard water into the line that is permanently heated to 140 °C and flushed with dry nitrogen gas. This permits instantaneous and complete vaporisation of the standard water, resulting in an artificial water background with well-known δ D and δ18O values. The speleothem sample is placed in a copper tube, attached to the line, and after system stabilisation it is crushed using a simple hydraulic device to liberate speleothem fluid inclusions water. The released water is carried by the nitrogen/standard water gas stream directly to a Picarro L1102-i for isotope determination. To test the accuracy and reproducibility of the line and to measure standard water during speleothem measurements, a syringe injection unit was added to the line. Peak evaluation is done similarly as in gas chromatography to obtain &delta D; and δ18O isotopic compositions of measured water aliquots. Precision is better than 1.5 ‰ for δ D and 0.4 ‰ for δ18O for water measurements for an extended range (-210 to 0 ‰ for δ D and -27 to 0 ‰ for δ18O) primarily dependent on the amount of water released from speleothem fluid inclusions and secondarily on the isotopic composition of the sample. The results show that WS-CRDS technology is suitable for speleothem fluid inclusion measurements and gives results that are comparable to the isotope ratio mass

  6. Radiocarbon dating

    International Nuclear Information System (INIS)

    Lazos R, L.

    2005-01-01

    The application of the radiocarbon dating in archaeology has not served only to solve problems related with the establishment of chronologies, but also in the development of archaeological methods of excavation and interpretation. This has been possible because the dating method by radiocarbon provides a common temporary scale that transcends the cultural and regional frontiers. It is even spoken of the revolution that has meant the fact that the application of this method has allowed to the archaeologist to pass from the construction of chronologies until the evaluation and dynamic interpretation of the archaeological data to build theories. This work explains and compares methods for the detection of 14 C, as the gas counting, the liquid scintillation counting and the mass spectrometry with accelerators. (Author)

  7. Thermoluminescence dating

    International Nuclear Information System (INIS)

    Price, D.M.

    1999-01-01

    Thermoluminescence (TL) dating of sediments depends upon the acquisition and long term stable storage of TL energy by crystalline minerals contained within a sedimentary unit. This energy is stored in the form of trapped electrons and quartz sand is the most commonly used mineral employed in the dating process. Prior to the final depositional episode it is necessary that any previously acquired TL is removed by exposure to sunlight. After burial the TL begins to build up again at a rate dependent upon the radiation flux delivered by long-lived isotopes of uranium, thorium and potassium. The presence of rubidium and cosmic radiation generally play a lesser but contributory roll, and the total radiation dose delivered to the TL phosphor is modified by the presence of water. The period since deposition is therefore measured by determining the total amount of stored TL energy, the palaeodose (P), and the rate at which this energy is acquired, the annual radiation dose (ARD). TL dating may be applied to eolian, fluvial, coastal and in some cases, marine sediments. the technique is also successfully applied to volcanic materials and to a certain extent to archeological specimens

  8. Speleothem stable isotope records for east-central Europe: resampling sedimentary proxy records to obtain evenly spaced time series with spectral guidance

    Science.gov (United States)

    Gábor Hatvani, István; Kern, Zoltán; Leél-Őssy, Szabolcs; Demény, Attila

    2018-01-01

    Uneven spacing is a common feature of sedimentary paleoclimate records, in many cases causing difficulties in the application of classical statistical and time series methods. Although special statistical tools do exist to assess unevenly spaced data directly, the transformation of such data into a temporally equidistant time series which may then be examined using commonly employed statistical tools remains, however, an unachieved goal. The present paper, therefore, introduces an approach to obtain evenly spaced time series (using cubic spline fitting) from unevenly spaced speleothem records with the application of a spectral guidance to avoid the spectral bias caused by interpolation and retain the original spectral characteristics of the data. The methodology was applied to stable carbon and oxygen isotope records derived from two stalagmites from the Baradla Cave (NE Hungary) dating back to the late 18th century. To show the benefit of the equally spaced records to climate studies, their coherence with climate parameters is explored using wavelet transform coherence and discussed. The obtained equally spaced time series are available at PANGAEA.875917" target="_blank">https://doi.org/10.1594/PANGAEA.875917.

  9. Effect of soil-rock system on speleothems weathering in Bailong Cave, Yunnan Province, China*

    Science.gov (United States)

    Wang, Jing; Song, Lin-hua

    2005-01-01

    Bailong Cave with its well-developed Middle Triassic calcareous dolomite’s system was opened as a show cave for visitors in 1988. The speleothem scenery has been strongly weathered as white powder on the outer layers. Study of the cave winds, permeability of soil-rock system and the chemical compositions of the dripping water indicated: (1) The cave dimension structure distinctively affects the cave winds, which were stronger at narrow places. (2) Based on the different soil grain size distribution, clay was the highest in composition in the soil. The response sense of dripping water to the rainwater percolation was slow. The density of joints and other openings in dolomite make the dolomite as mesh seepage body forming piles of thin and high columns and stalactites. (3) Study of 9 dripping water samples by HYDROWIN computer program showed that the major mineral in the water was dolomite. PMID:15682505

  10. Similar speleothem δ18O signals indicating diverging climate variations in inland central Asia and monsoonal south Asia during the Holocene

    Science.gov (United States)

    Jin, Liya; Zhang, Xiaojian

    2017-04-01

    High-resolution and precisely dated speleothem oxygen isotope (δ18O) records from Asia have provided key evidence for past monsoonal changes. It is found that δ18O records of stalagmites from Kesang Cave (42°52'N, 81°45'E, Xinjiang, China) in inland central Asia were very similar to those from Qunf Cave (17°10'N, 54°18'E, southern Oman) in South Asia, shifting from light to heavy throughout the Holocene, which was regarded as a signal that strong Asian summer monsoon (ASM) may have intruded into the Kesang Cave site and/or adjacent areas in inland central Asia to produce heavy rainfall during the high insolation times (e.g. the early Holocene). However, this is in contrast to conclusions based on other Holocene proxy records and modeling simulations, showing a persistent wetting trend in arid central Asia during the Holocene with a dryer condition in the early Holocene and the wettest condition in the late Holocene. With an analysis of model-proxy data comparison, we revealed a possible physical mechanism responsible for the Holocene evolution of moisture/precipitation in Asian summer monsoon (ASM)-dominated regions and that in the inland central Asia. It is revealed that a recurrent circumglobal teleconnection (CGT) pattern in the summertime mid-latitude circulation of the Northern Hemisphere was closely related to the ASM and the climate of inland central Asia, acting as a bridge linking the ASM to insolation, high-latitude forcing (North Atlantic sea surface temperature (SST)), and low-latitude forcing (tropical Ocean SST). Also, the CGT influence speleothem δ18O values in South Asia via its effect on the amount of precipitation. In addition, the moisture source from the Indian Ocean is associated with relatively high δ18O values compared with that from the North Atlantic Ocean, leading to increased precipitation δ18O values. Hence, the CGT has probably been the key factor responsible for the in-phase relationship in speleothem δ18O values (Kesang Cave

  11. Oxygen Isotope Speleothem record of Decadal and Multidecadal Atlantic Oscillations over the last millennium in Southwestern Morocco

    Science.gov (United States)

    Ait Brahim, Yassine; Sha, LiJuan; Sifeddine, Abdelfettah; Cheng, Hai; Bouchaou, Lhoussaine; Da Cruz Junior, Francisco William; Khodri, Myriam; Peerbocus, Nawaaz; Mariller, Alexandre; Apaestegui, James; Guyot, Jean-Loup; Auler, Augusto; Hassane Beraaouz, El

    2016-04-01

    In this work, we present a stable oxygen isotope (δ18O) speleothem record from Ifoulki cave located South-West of Morocco (N 30°42'29'', W 09°19'39'' and 1267 meters above sea level). The age model, based on eighteen U-Th dates, reveals that the record covers the AD 790-1953 period with a data resolution of ~1.7 years. Stable oxygen isotope variations show substantial decadal to multi-decadal swings between dry and humid periods. The Medieval Climate Anomaly (MCA) is characterized by the longest period with δ18O values above the average, suggestive of pronounced drying possibly as a response to positive North Atlantic Oscillation (NAO) phases and increased volcanic activity during this period. However, at least two short wet phases are recognized during the MCA in Morocco, with peaks centered on the years AD 1040 and AD 1190 and seem to overlap with negative NAO phases as recorded in a recently published NAO reconstruction for the last millennium. During the next centuries, the NAO again depicts predominantly negative values and the δ18O drops below the average during the Little Ice Age (LIA). Furthermore, a striking resemblance is observed between our record and another recently published stalagmite record from the Piste cave in Northeastern Morocco, which is quite remarkable given the different type of tracers (δ18O vs. Mg and Sr) obtained from different environments (Western High Atlas vs. Northeastern Middle Atlas and ~634 km away). Comparison with regional paleorecords from other studies also reveals the replication of many characteristic climate features from the last millennium, first detected in Northern Morocco and the Iberian Peninsula. In particular, the evidence of generally dry conditions during the MCA and wetter conditions in the LIA, which is confirmed by all the paleorecords. These similarities indicate coherent climate variability in Northwest Africa and the Iberian Peninsula and suggest a strong regional control of the NAO during the last

  12. Hemispherically in-phase precipitation variability over the last 1700 years in a Madagascar speleothem record

    Science.gov (United States)

    Scroxton, Nick; Burns, Stephen J.; McGee, David; Hardt, Ben; Godfrey, Laurie R.; Ranivoharimanana, Lovasoa; Faina, Peterson

    2017-05-01

    Paleoclimate studies of tropical rainfall have led to a recognition of a predominant pattern of anti-phase behavior between the Northern and Southern hemispheres at both orbital and millennial timescales. Less certain is how regional tropical rainfall patterns have changed in the late Holocene, under boundary conditions and on timescales which are most relevant to the tropics' response to a warming world. Several high-resolution southern hemisphere rainfall records are at odds with meridional movement of the mean Inter-Tropical Convergence Zone location as the major driver of Holocene tropical rainfall variability, with regional precipitation patterns resembling modern day El-Niño Southern Oscillation end members. To test emerging ideas on sub-millennial tropical rainfall variability, additional records from the southern hemisphere are required. We present a new speleothem δ18O record from Anjohibe Cave, northwestern Madagascar, which provides a quasi-annual record of monsoonal strength and precipitation amount for the last 1700 years. The majority of δ18O variability in the record is at the decadal scale, and shows little to no correlation with major climate indices or cyclical climate drivers. At lower frequencies, changes in mean speleothem δ18O show good correlation with other regional precipitation records both north and south of the equator. The regional coherency of tropical rainfall across the west Indian Ocean resembles expansion and contraction of the tropical rain belt and positive-Indian Ocean Dipole-like conditions at different timescales. The cause of this coherency could be related to symmetrical changes in continental sensible heating, or to a low frequency sea surface temperature climate mode.

  13. U-series in zircon and 40Ar/39Ar geochronology reveal the most recent stage of a supervolcanic cycle in the Altiplano-Puna Volcanic Complex, Central Andes

    Science.gov (United States)

    Tierney, C.; de Silva, S. L.; Schmitt, A. K.; Jicha, B.; Singer, B. S.

    2010-12-01

    The ignimbrite flare up that produced the Altiplano-Puna Volcanic Complex of the Central Andes is characterized by episodic supervolcanism over a ~10 Ma time-span that climaxed about 4Ma. Since peak activity, the temporal and spatial record of volcanism suggests a waning of the system with only one other supervolcanic eruption at 2.6Ma. The most recent phase of volcanism from the APVC comprises a series of late Pleistocene domes that share a general petrochemical resemblance to the ignimbrites. New U-series data on zircons and high precision 40Ar/39Ar age determinations reveal that these effusive eruptions represent a temporally coherent magmatic episode. The five largest domes (Chao, Chillahuita, Chanka, Chascon-Runtu Jarita, and Tocopuri) have a combined volume >40 km3, and are distributed over an elliptical area of over 3000km2 centered at 22°S 68°W. They are crystal rich (>50%) dacites to rhyolites. New 40Ar/39Ar age determinations on biotite for the domes range range from 108±6 to 190±50 ka. However, 40Ar/39Ar ages from sanidine for some of the domes are more precise and span from 87±4 to 97±2 ka. We therefore interpret the eruption age of all these domes to be ~90 - 100 ka. This is consistent with SIMS U-series crystallization ages from the rims of 66 zircon crystals from four of the domes that reveal a fairly continuous spread of ages from ~90 ka to >300 ka with potentially common peaks in zircon ages at 100 ka and ~200 ka. U-Pb dating on the interiors of some of these zircon crystals indicates crystallization ages of up to 1.5 Ma. The common peaks of zircon crystallization between domes suggest that magma that fed these domes shared a larger regional source. Furthermore, the large volume of this potential source and the crystal-rich nature of the lava imply that this source was likely a large body of crystal-mush. The continuous nature of the zircon rim age population indicates that the residence time of this magma body was likely >200kyr. Potential

  14. Late Holocene climate and environmental change from Asiul cave speleothems: interpretations in light of modern cave monitoring.

    Science.gov (United States)

    Smith, Andrew; Wynn, Peter; Barker, Philip; Leng, Melanie; Noble, Steve; Tych, Wlodek

    2017-04-01

    Northern Iberia offers an excellent location to study fluctuations in North Atlantic Ocean (NA) conditions and the impact that changes in the NA have on atmospheric systems, which dominate Europe's climate. Two speleothems from Cueva de Asiul (Matienzo, N. Spain) have been used to reconstruct rainfall variability in N. Spain throughout the Holocene (Smith et al., 2016a). The carbonate δ18O records from these speleothems are interpreted in the light of a rigorous modern cave monitoring program undertaken at Cueva de Asiul (Smith et al., 2016b). Drip water δ18O reflects a modern rainfall amount effect whilst δ13C appears influenced by Prior Calcite Precipitation (PCP) in the short term and changes in vegetation at long timescales. The speleothem δ18O shows that long duration ( 1500 year) cycles in wetting and drying are prevalent in N. Spain during the Holocene and that dry climate phases are related to the timing of cold events (Bond et al., 2001) in the NA. Here we look in more detail at one of these speleothems, assessing both δ18O and δ13C during the last two thousand years. We show that Cueva de Asiul speleothems not only preserve long duration climate cycles in δ18O, but that they also appear influenced by shorter duration changes in the North Atlantic Oscillation (NAO), in-sync with other NAO archives (Olsen et al., 2012). However, the Cueva de Asiul record does not appear to preserve a predominately positive NAO signal during the Medieval Climate Anomaly (MCA) as is common within many European archives (Trouet et al., 2009), possibly due to the sites' close proximity to the NA and localised oceanic weather systems (Moreno et al., 2012). Alongside climatic changes, the speleothem δ13C shows a clear transition toward higher isotope values around 360 years BP (BP=1950), signalling a major environmental change in the region possibly due to anthropogenic removal of vast swathes of natural forest to support ship building and industry related to the Spanish

  15. {sup 14}C AMS dating Yongcheon cave

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.H., E-mail: jefflee@snu.ac.kr [AMS Lab., NCIRF, Seoul National University, Seoul 151-742 (Korea, Republic of); Choe, K. [AMS Lab., NCIRF, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, J.C. [Dept. of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Choi, S.H.; Kang, J.; Song, S.; Song, Y.M. [AMS Lab., NCIRF, Seoul National University, Seoul 151-742 (Korea, Republic of); Jang, J.G. [Jeju National Museum, Jeju 690-782 (Korea, Republic of)

    2013-01-15

    The biggest island in South Korea is Jeju Island, which lies 80 km south of the mainland and has one shield volcano, Mt. Halla. The volcanic island and its lava tubes were added to the world heritage list by UNESCO in 2007. Among the many lava tubes on the island, a unique cave had been accidentally found in 2005 while some workers were replacing a telephone pole. Until the discovery, it had been completely isolated from the outside by naturally-built sand blocks. Yongcheon cave is a lime-decorated lava tube showing both the properties of a volcanic lava tube and a limestone cave. This cave, about 3 km in length, is acknowledged to be the best of this type in the world and includes a large clean-water lake, lava falls, and richly developed speleothems inside it. Even though there is archaeological evidence from well preserved pottery that ancient people entered this place, the preservation of artifacts was ensured by a geological change that made later entrance difficult. We have collected charcoal samples scattered around the cave and dated them using AMS. Ages were in the range of ca. 1570-1260 BP (A.D. 340-880) and this corresponds to the Ancient Three Kingdoms and the Unified Silla era in Korean history. The {sup 14}C AMS measurement results presented in this paper on wood charcoal provide precise dates which will be very useful not only to clarify the nature of human activities in this cave but also to provide reference dates when comparing other dating methods.

  16. 14C AMS dating Yongcheon cave

    International Nuclear Information System (INIS)

    Lee, J.H.; Choe, K.; Kim, J.C.; Choi, S.H.; Kang, J.; Song, S.; Song, Y.M.; Jang, J.G.

    2013-01-01

    The biggest island in South Korea is Jeju Island, which lies 80 km south of the mainland and has one shield volcano, Mt. Halla. The volcanic island and its lava tubes were added to the world heritage list by UNESCO in 2007. Among the many lava tubes on the island, a unique cave had been accidentally found in 2005 while some workers were replacing a telephone pole. Until the discovery, it had been completely isolated from the outside by naturally-built sand blocks. Yongcheon cave is a lime-decorated lava tube showing both the properties of a volcanic lava tube and a limestone cave. This cave, about 3 km in length, is acknowledged to be the best of this type in the world and includes a large clean-water lake, lava falls, and richly developed speleothems inside it. Even though there is archaeological evidence from well preserved pottery that ancient people entered this place, the preservation of artifacts was ensured by a geological change that made later entrance difficult. We have collected charcoal samples scattered around the cave and dated them using AMS. Ages were in the range of ca. 1570-1260 BP (A.D. 340–880) and this corresponds to the Ancient Three Kingdoms and the Unified Silla era in Korean history. The 14 C AMS measurement results presented in this paper on wood charcoal provide precise dates which will be very useful not only to clarify the nature of human activities in this cave but also to provide reference dates when comparing other dating methods.

  17. Analytical pyrolysis and stable isotope analyses reveal past environmental changes in coralloid speleothems from Easter Island (Chile).

    Science.gov (United States)

    Miller, Ana Z; De la Rosa, José M; Jiménez-Morillo, Nicasio T; Pereira, Manuel F C; González-Pérez, José A; Calaforra, José M; Saiz-Jimenez, Cesareo

    2016-08-26

    This study comprises an innovative approach based on the combination of chromatography (analytical pyrolysis and pyrolysis compound-specific isotope analysis (Py-CSIA)), light stable isotopes, microscopy and mineralogy analyses to characterize the internal layering of coralloid speleothems from the Ana Heva lava tube in Easter Island (Chile). This multidisciplinary proxy showed that the speleothems consist of banded siliceous materials of low crystallinity with different mineralogical compositions and a significant contribution of organic carbon. Opal-A constitutes the outermost grey layer of the coralloids, whereas calcite and amorphous Mg hydrate silicate are the major components of the inner whitish and honey-brown layers, respectively. The differences found in the mineralogical, elemental, molecular and isotopic composition of these distinct coloured layers are related to environmental changes during speleothem development. Stable isotopes and analytical pyrolysis suggested alterations in the water regime, pointing to wetter conditions during the formation of the Ca-rich layer and a possible increase in the amount of water dripping into the cave. The trend observed for δ(15)N values suggested an increase in the average temperature over time, which is consistent with the so-called climate warming during the Holocene. The pyrolysis compound-specific isotope analysis of each speleothem layer showed a similar trend with the bulk δ(13)C values pointing to the appropriateness of direct Py-CSIA in paleoenvironmental studies. The δ(13)C values for n-alkanes reinforced the occurrence of a drastic environmental change, indicating that the outermost Opal layer was developed under drier and more arid environmental conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Palaeoclimate significance of speleothems in crystalline rocks: a test case from the Late Glacial and early Holocene (Vinschgau, northern Italy)

    Science.gov (United States)

    Koltai, Gabriella; Cheng, Hai; Spötl, Christoph

    2018-03-01

    Partly coeval flowstones formed in fractured gneiss and schist were studied to test the palaeoclimate significance of this new type of speleothem archive on a decadal-to-millennial timescale. The samples encompass a few hundred to a few thousand years of the Late Glacial and the early Holocene. The speleothem fabric is primarily comprised of columnar fascicular optic calcite and acicular aragonite, both indicative of elevated Mg / Ca ratios in the groundwater. Stable isotopes suggest that aragonite is more prone to disequilibrium isotope fractionation driven by evaporation and prior calcite/aragonite precipitation than calcite. Changes in mineralogy are therefore attributed to these two internal fracture processes rather than to palaeoclimate. Flowstones formed in the same fracture show similar δ18O changes on centennial scales, which broadly correspond to regional lacustrine δ18O records, suggesting that such speleothems may provide an opportunity to investigate past climate conditions in non-karstic areas. The shortness of overlapping periods in flowstone growth and the complexity of in-aquifer processes, however, render the establishment of a robust stacked δ18O record challenging.

  19. Reconstructing Hydrologic Variability in Southwestern North America Using Speleothem Proxies and Precipitation Isotopes from California

    Science.gov (United States)

    McCabe-Glynn, Staryl

    Precipitation in southwestern North America has exhibited significant natural variability over the past few thousand years. This variability has been attributed to sea surface temperature regimes in the Pacific and Atlantic oceans, and to the attendant shifts in atmospheric circulation patterns. In particular, decadal variability in the North Pacific has influenced precipitation in this region during the twentieth century, but links to earlier droughts and pluvials are unclear. Here I assess these links using delta18 O measurements from a speleothem from southern California that spans AD 854-- 2007. I show that variations in the oxygen isotopes of the speleothem correlate to sea surface temperatures in the Kuroshio Extension region of the North Pacific, which affect the atmospheric trajectory and isotopic composition of moisture reaching the study site. Interpreting our speleothem data as a record of sea surface temperatures in the Kuroshio Extension, I find a strong 22-year periodicity, suggesting a persistent solar influence on North Pacific decadal variability. A comparison with tree-ring records of precipitation during the past millennium shows that some droughts occurred during periods of warmth in the Kuroshio Extension, similar to the instrumental record. However, other droughts did not and instead were likely influenced by other factors. The carbon isotope record indicates drier conditions are associated with higher delta13C values and may be a suitable proxy for reconstructing past drought variability. More research is needed to determine the controls on trace element concentrations. Finally, I find a significant increase in sea surface temperature variability over the past 150 years, which may reflect an influence of greenhouse gas concentrations on variability in the North Pacific. While drought is a common feature of climate in this region, most climate models also project extreme precipitation events to increase in frequency and severity because the

  20. Speleothem Mg-isotope time-series data from different climate belts

    Science.gov (United States)

    Riechelmann, S.; Buhl, D.; Richter, D. K.; Schröder-Ritzrau, A.; Riechelmann, D. F. C.; Niedermayr, A.; Vonhof, H. B.; Wassenburg, J.; Immenhauser, A.

    2012-04-01

    Speleothem Mg-isotope time-series data from different climate belts Sylvia Riechelmann (1), Dieter Buhl(1), Detlev K. Richter (1), Andrea Schröder-Ritzrau (2), Dana F.C. Riechelmann (3), Andrea Niedermayr (1), Hubert B. Vonhof (4) , Jasper Wassenburg (1), Adrian Immenhauser (1) (1) Ruhr-University Bochum, Institute for Geology, Mineralogy and Geophysics, Universitätsstraße 150, D-44801 Bochum, Germany (2) Heidelberg Academy of Sciences, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany (3) Johannes Gutenberg-University Mainz, Institute of Geography, Johann-Joachim-Becher-Weg 21, D-55128 Mainz, Germany (4) Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands The Magnesium isotope proxy in Earth surface research is still underexplored. Recently, field and laboratory experiments have shed light on the complex suite of processes affecting Mg isotope fractionation in continental weathering systems. Magnesium-isotope fractionation in speleothems depends on a series of factors including biogenic activity and composition of soils, mineralogy of hostrock, changes in silicate versus carbonate weathering ratios, water residence time in the soil and hostrock and disequilibrium factors such as the precipitation rate of calcite in speleothems. Furthermore, the silicate (here mainly Mg-bearing clays) versus carbonate weathering ratio depends on air temperature and rainfall amount, also influencing the soil biogenic activity. It must be emphasized that carbonate weathering is generally dominant, but under increasingly warm and more arid climate conditions, silicate weathering rates increase and release 26Mg-enriched isotopes to the soil water. Furthermore, as shown in laboratory experiments, increasing calcite precipitation rates lead to elevated delta26Mg ratios and vice versa. Here, data from six stalagmite time-series Mg-isotope records (Thermo Fisher Scientific Neptune MC-ICP-MS) are shown. Stalagmites

  1. Dating of the Basal Aurignacian Sandwich at Abric Romanı́ (Catalunya, Spain) by Radiocarbon and Uranium-Series

    Science.gov (United States)

    Bischoff, James L.; Ludwig, Kenneth R.; Garcia, Jose Francisco; Carbonell, E.; Vaquero, Manola; Stafford, Thomas W.; Jull, A.J.T.

    1994-01-01

    Abric Romani{dotless}??, a rock shelter located near Barcelona, Spain, contains a charcoal-bearing basal Aurignacian occupation level sandwiched between beds of moss-generated carbonate. The Aurignacian culture is the oldest artefact industry in Europe with which anatomically modern human remains have been associated. Radiocarbon analysis of charcoal fragments by accelerator mass spectrometry (AMS) dates the basal Aurignacian to about 37 ?? 2 ka bp. U-series analyses by alpha spectrometry (AS) and mass spectrometry (MS) date the enclosing carbonate to 43 ?? 1 ka bp. These results confirm the great antiquity of the Aurignacian in northern Spain and support the similar AMS dates from El Castillo and l'Arbreda caves. They also show that radiocarbon dates are significantly younger than U-series at 40 ka bp, as predicted by theory. ?? 1994 Academic Press. All rights reserved.

  2. Quantifying chemical weathering rates along a precipitation gradient on Basse-Terre Island, French Guadeloupe: new insight from U-series isotopes in weathering rinds

    Science.gov (United States)

    Engel, Jacqueline M.; May, Linda; Sak, Peter B.; Gaillardet, Jerome; Ren, Minghua; Engle, Mark A.; Brantley, Susan L.

    2016-01-01

    Inside soil and saprolite, rock fragments can form weathering clasts (alteration rinds surrounding an unweathered core) and these weathering rinds provide an excellent field system for investigating the initiation of weathering and long term weathering rates. Recently, uranium-series (U-series) disequilibria have shown great potential for determining rind formation rates and quantifying factors controlling weathering advance rates in weathering rinds. To further investigate whether the U-series isotope technique can document differences in long term weathering rates as a function of precipitation, we conducted a new weathering rind study on tropical volcanic Basse-Terre Island in the Lesser Antilles Archipelago. In this study, for the first time we characterized weathering reactions and quantified weathering advance rates in multiple weathering rinds across a steep precipitation gradient. Electron microprobe (EMP) point measurements, bulk major element contents, and U-series isotope compositions were determined in two weathering clasts from the Deshaies watershed with mean annual precipitation (MAP) = 1800 mm and temperature (MAT) = 23 °C. On these clasts, five core-rind transects were measured for locations with different curvature (high, medium, and low) of the rind-core boundary. Results reveal that during rind formation the fraction of elemental loss decreases in the order: Ca ≈ Na > K ≈ Mg > Si ≈ Al > Zr ≈ Ti ≈ Fe. Such observations are consistent with the sequence of reactions after the initiation of weathering: specifically, glass matrix and primary minerals (plagioclase, pyroxene) weather to produce Fe oxyhydroxides, gibbsite and minor kaolinite.Uranium shows addition profiles in the rind due to the infiltration of U-containing soil pore water into the rind as dissolved U phases. U is then incorporated into the rind as Fe-Al oxides precipitate. Such processes lead to significant U-series isotope disequilibria in the rinds

  3. ESR/U-series study of teeth recovered from the palaeo-anthropological stratum of the Dali Man site (Shaanxi Province, China)

    International Nuclear Information System (INIS)

    Yin, G.; Han, F.; Bahain, J.J.; Tissoux, H.; Falgueres, Ch.; Han, F.; Shao, Q.; Shen, G.; Shao, Q.; Dolo, J.M.

    2011-01-01

    The Dali skull is a key fossil for understanding human evolution in China. It has been attributed either to an archaic Homo sapiens, an evolved Homo erectus or to other species of Homo, such as Homo heidelbergensis. The cranium was discovered in 1978 in Shaanxi Province in a fluvial terrace which was recovered by a loessic sequence including two interglacial palaeo-soils. ESR/U-series data analyses were carried out on several teeth recovered from the palaeo-anthropological level. Four samples exhibit different kinds of uranium-uptake behaviour, but the results seem to indicate that the cranium is coeval with Marine Isotope Stage (MIS) 8 and that some teeth might be reworked from older deposits. (authors)

  4. Measurement of distribution coefficients of U series radionuclides on soils under shallow land environment (2). pH dependence of distribution coefficients

    International Nuclear Information System (INIS)

    Sakamoto, Yoshiaki; Takebe, Shinichi; Ogawa, Hiromichi; Inagawa, Satoshi; Sasaki, Tomozou

    2001-01-01

    In order to study sorption behavior of U series radionuclides (Pb, Ra, Th, Ac, Pa and U) under aerated zone environment (loam-rain water system) and aquifer environment (sand-groundwater system) for safety assessment of U bearing waste, pH dependence of distribution coefficients of each element has been obtained. The pH dependence of distribution coefficients of Pb, Ra, Th, Ac and U was analyzed by model calculation based on aqueous speciation of each element and soil surface charge characteristics, which is composed of a cation exchange capacity and surface hydroxyl groups. From the model calculation, the sorption behavior of Pb, Ra, Th, Ac and U could be described by a combination of cation exchange reaction and surface-complexation model. (author)

  5. U-series vs 14C ages of deep-sea corals from the southern Labrador Sea: Sporadic development of corals and geochemical processes hampering estimation of ambient water ventilation ages

    Science.gov (United States)

    Hillaire-Marcel, Claude; Maccali, Jenny; Ménabréaz, Lucie; Ghaleb, Bassam; Blénet, Aurélien; Edinger, Evan

    2017-04-01

    Deep-sea scleractinian corals were collected with the remotely operated ROPOS vehicle off Newfounland. Fossil specimens of Desmophyllum dianthus were raised from coral graveyards at Orphan Knoll (˜1700m depth) and Flemish cap (˜2200 m depth), while live specimens were collected directly in overlying steep rock slopes. D. dianthus has an aragonitic skeleton and is thus particularly suited for U-Th dating. We obtained > 70 U-series ages along with > 20 14C measurements. Results display a discrete age distribution with two age clusters: a Bølling-Allerød and Holocene cluster with > 20 samples, and a Marine Isotope Stage (MIS) 5c cluster with ˜50 samples. Only two samples lay outside these clusters, at ˜ 64 ka and at ˜181 ka. Contrary to the New England seamounts where coral presence seems to have been continue through the last 70 ka, Orphan Knoll and Flemish Cap graveyards are marked by the absence of preserved specimens from MIS 2 to MIS 4 and throughout MIS 6. For filter-feeding deep-sea corals, access to food-rich waters is essential. Hence the Holocene and MIS 5 clusters observed in the Labrador basin might represent intervals linked to high food availability, either through production in the overlying water column, more effectively in relation to particulate and dissolved organic carbon transport via an active Western Boundary Undercurrent. Comparison of 230Th-ages vs 14C-ages in order to document changes in ventilation ages of the ambient water masses is equivocal due to the presence of some diagenetic and/or initial 230Th-excess. In addition, discrete diagenetic U-fluxes can be documented from 234U/238U vs 230Th/238U data. They point to a recent winnowing of sediment overlying the fossil corals that we link to the Holocene intensification of the Western Boundary Undercurrent, which resulted in driving Fe-Mn coatings.

  6. Urbanization impact on sulfur content of groundwater revealed by the study of urban speleothem-like deposits: Case study in Paris, France.

    Science.gov (United States)

    Pons-Branchu, E; Roy-Barman, M; Jean-Soro, L; Guillerme, A; Branchu, P; Fernandez, M; Dumont, E; Douville, E; Michelot, J L; Phillips, A M

    2017-02-01

    Speleothem-like deposits that develop underground in urban areas are an archive of the environmental impact of anthropic activities that has been little studied so far. In this paper, the sulfate content in shallow groundwater from northern Paris (France) is compared with the sulfur content in two 300-year-old urban carbonate deposits that grew in a historical underground aqueduct. The present-day waters of the aqueduct have very high sulfur and calcium contents, suggesting pollution from gypsum dissolution. However, geological gypsum levels are located below the water table. Sulfur content was measured by micro-X-ray fluorescence in these very S-rich carbonate deposits (0.5 to 1% of S). A twofold S increase during the second half of the 1800s was found in both samples. These dates correspond to two major periods of urbanization above the site. We discus three possible S sources: anthropic sources (industries, fertilizers…), volcanic eruptions and input within the water through gypsum brought for urbanization above the studied site (backfill with quarry waste) since the middle of the 19th century. For the younger second half of the studied section, S input from gypsum brought during urbanization was confirmed by the study of isotopic sulfur composition (δ 34 S=+15.2‰ at the top). For the oldest part, several sulfur peaks could be related to early industrial activity in Paris, that caused high local air pollution, as reported in historical archives but also to historical gypsum extraction. This study provides information on the origin and timing of the very high SO 4 2- levels measured nowadays within the shallow groundwater, thus demonstrating the interest in using carbonate deposits in urban areas as a proxy for the history of urbanization or human activities and their impact on water bodies. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Dating and Sexual Feelings

    Science.gov (United States)

    ... Home Body Your sexuality Dating and sexual feelings Dating and sexual feelings Thinking about romance, starting to ... you learn how to stay healthy and strong. Dating older guys top If you date someone even ...

  8. Methodology of the carbonates dating by the uranium series unbalance by mass spectrometry

    International Nuclear Information System (INIS)

    Lima, Barbara Alcantara Ferreira

    2006-01-01

    There are many dating methods largely used according to the kind of material to be dated. Methods that rely on the time-dependency of geochemical disequilibrium between daughter and parent isotope, from the '2 38 U, 235 U and 232 Th natural decay system, whose final members are stable Pb isotopes, are the most useful in a broader variety of geological, hydrological and archaeological problems. The use of this method in cave deposits like speleothems and clastic sediments proved to be a powerful tool to study past climatic and environmental changes. Speleothems like stalagmites are frequently used in paleoenvironmental interpretations. This method may be applied to rocks and underground water dating, erosion studies, transport and sedimentation processes, interactions between rock-groundwater, among others. The present work focuses on the chemical preparation of the U-Th method including the chemical procedures to avoid laboratory contamination and the mass spectrometer precise calibration in order to get high reproducibility. The process has many steps: samples preparation; digestion and chromatographic separation using standards and samples already dated in other laboratories; determination of the isotopic ratios by mass spectrometers, and a case study based on a stalagmite from Joao Arruda cave, Bonito, Mato Grosso State, Brazil. The obtained data shows the reliability of the method works, mostly in relation to co precipitation of U and Th and to the chromatographic separation of these metals. It is also observed that the obtained dates are within the errors for each sample and are very similar to the dates obtained in other laboratories (validated to this methodology). Further improvements are necessary to achieve better results, mostly related to the reading method in the MC-ICP-MS. The case study in the JA-5 stalagmite shows that it stopped growing around 2,0 ky. This is a different result from that obtained on JA-3 stalagmite, from the same cave, but placed

  9. Lessons learned from oxygen isotopes in modern precipitation applied to interpretation of speleothem records of paleoclimate from eastern Asia

    Science.gov (United States)

    Dayem, Katherine E.; Molnar, Peter; Battisti, David S.; Roe, Gerard H.

    2010-06-01

    Variability in oxygen isotope ratios collected from speleothems in Chinese caves is often interpreted as a proxy for variability of precipitation, summer precipitation, seasonality of precipitation, and/or the proportion of 18O to 16O of annual total rainfall that is related to a strengthening or weakening of the East Asian monsoon and, in some cases, to the Indian monsoon. We use modern reanalysis and station data to test whether precipitation and temperature variability over China can be related to changes in climate in these distant locales. We find that annual and rainy season precipitation totals in each of central China, south China, and east India have correlation length scales of ∼ 500 km, shorter than the distance between many speleothem records that share similar long-term time variations in δ18O values. Thus the short distances of correlation do not support, though by themselves cannot refute, the idea that apparently synchronous variations in δ18O values at widely spaced (> 500 km) caves in China are due to variations in annual precipitation amounts. We also evaluate connections between climate variables and δ18O values using available instrumental measurements of δ18O values in precipitation. These data, from stations in the Global Network of Isotopes in Precipitation (GNIP), show that monthly δ18O values generally do not correlate well with either local precipitation amount or local temperature, and the degree to which monthly δ18O values do correlate with them varies from station to station. For the few locations that do show significant correlations between δ18O values and precipitation amount, we estimate the differences in precipitation amount that would be required to account for peak-to-peak differences in δ18O values in the speleothems from Hulu and Dongge caves, assuming that δ18O scales with the monthly amount of precipitation or with seasonal differences in precipitation. Insofar as the present-day relationship between δ18O

  10. Setting a date

    International Nuclear Information System (INIS)

    Moore, Glenis.

    1987-01-01

    Dating techniques are discussed and explained. The age range and sensitivity of different techniques are given. Potassium/argon dating, amino-acid dating, radiocarbon dating, dendrochronology, thermoluminescence and geomagnetic field dating are all mentioned. Each technique is explained and a brief history given. The techniques and equipment used by the British Museum, and some examples of archaeological articles dated are mentioned. (UK)

  11. Astrobiology Training in Lava Tubes (ATiLT): Characterizing coralloid speleothems in basaltic lava tubes as a Mars analogue

    Science.gov (United States)

    Ni, J.; Leveille, R. J.; Douglas, P.

    2017-12-01

    Coralloid speleothems or cave corals are small mineralised nodes that can take a variety of forms, and which develop through groundwater seepage and water-rock interaction in caves. They are found commonly on Earth in a plethora of caves, including lava tubes. Since lava tubes have been identified on the surface of Mars from remotely sensed images, there has been interest in studying Earth's lava tube systems as an analogue for understanding Martian lava environments. If cave minerals were found on Mars, they could indicate past or present water-rock interaction in the Martian subsurface. Martian lava tubes could also provide insights into habitable subsurface environments as well as conditions favourable for the synthesis and preservation of biosignatures. One of the aims of the Astrobiology Training in Lava Tubes (ATiLT) project is to analyze biosignatures and paleoenvironmental indicators in secondary cave minerals, which will be looked at in-situ and compared to collected field samples. In this study, secondary mineralization in lava cave systems from Lava Beds National Monument, CA is examined. In the field, coralloid speleothems have been observed growing on all surfaces of the caves, including cave ceilings, floors, walls and overhangs. They are also observed growing adjacent to biofilms, which sometimes fill in the cracks of the coralloid nodes. Preliminary results show the presence of opal, calcite, quartz and other minor minerals in the speleothems. This study seeks to understand the formation mechanism and source of these secondary minerals, as well as determine their possible relation to the biofilms. This will be done through the analysis of the water chemistry, isotope geochemistry and microscale mineralogy.

  12. Assessing Covariation of Holocene Monsoon Intensity and Local Moisture Conditions in Eastern and Southwestern Amazon Basin Using Speleothem δ18O and 87Sr/86Sr Values

    Science.gov (United States)

    Ward, B. M.; Wong, C. I.; Novello, V. F.; Silva, L.; McGee, D.; Cheng, H.; Wang, X.; Edwards, R. L.; Cruz, F. W., Sr.; Santos, R. V.

    2017-12-01

    δ18O records from South America offer insight into past variability of the South American Monsoon System (SAMS). Potential, however, for understanding local moisture conditions is limited as precipitation δ18O is strongly influenced by regional climate dynamics. Here we create Holocene speleothem 87Sr/86Sr records at 200-yr resolution using TIMS methods in the Center for Isotope Geochemistry at Boston College to complement existing Holocene δ18O speleothem records and investigate local moisture conditions above caves located in the eastern Amazon Basin (PAR - 4°S, 55°W) and southwestern Brazil (JAR - 21°S, 56°W). Speleothem 87Sr/86Sr variability is interpreted to reflect differences in the extent of water-rock interaction due to differences in infiltration rates under wet and dry conditions. Drier conditions promote longer residence time, enhanced water-rock interaction, and greater evolution of dripwater 87Sr/86Sr values from an initial isotopic signature acquired from the soil to the signature of the cave host rock. PAR speleothem 87Sr/86Sr values range from 0.71024 to 0.71067 and are bracketed by soil (0.71710 to 0.70956) and bedrock (0.70852 to 0.70899) values. JAR speleothem 87Sr/86Sr values range from 0.71216 to 0.71539 and are greater than bedrock values (0.70825 to 0.71219), although some speleothem values exceed the single analysis conducted of the soil isotopic composition (0.71473). JAR speleothem 87Sr/86Sr values increase from the early to mid Holocene, consistent with increase in local moisture availability associated with intensification of the SAMS suggested by decreasing δ18O values in many records from the region. Speleothem 87Sr/86Sr values at JAR decrease from the mid to late Holocene, consistent with an increase in δ18O values at PAR that suggest a decline in monsoon intensity. 87Sr/86Sr variability at JAR, however, is positively correlated with the δ18O record. Preliminary 87Sr/86Sr results from PAR are only broadly consistent with

  13. Sulphate partitioning into calcite: Experimental verification of pH control and application to seasonality in speleothems

    Science.gov (United States)

    Wynn, Peter M.; Fairchild, Ian J.; Borsato, Andrea; Spötl, Christoph; Hartland, Adam; Baker, Andy; Frisia, Silvia; Baldini, James U. L.

    2018-04-01

    Carbonate-associated sulphate (CAS) is a useful carrier of palaeoenvironmental information throughout the geologic record, particularly through its stable isotope composition. However, a paucity of experimental data restricts quantitative understanding of sulphate incorporation into carbonates, and consequently CAS concentrations and their diagenetic modifications are rarely interpreted. However, in the case of calcite speleothems, the remarkably high-resolution CAS records which are obtainable via modern microanalytical techniques represent a potentially invaluable source of palaeoenvironmental information. Here, we describe the results of controlled experiments of sulphate co-precipitation with calcite in freshwater solutions where pH, saturation state, and sulphate concentration were varied independently of each other. Solution pH is confirmed as the principal control on sulphate incorporation into calcite. The relative efficiency of incorporation was calculated as a partition coefficient DSO4 = (mSO4/mCO3)solid/(mSO4/mCO3)solution. High crystal growth rates (driven by either pH or saturation state) encouraged higher values of DSO4 because of an increasing concentration of defect sites on crystal surfaces. At low growth rates, DSO4 was reduced due to an inferred competition between sulphate and bicarbonate at the calcite surface. These experimental results are applied to understand the incorporation of sulphate into speleothem calcite. The experimentally determined pH-dependence suggests that strong seasonal variations in cave air PCO2 could account for annual cycles in sulphate concentration observed in stalagmites. Our new experimentally determined values of DSO4 were compared with DSO4 values calculated from speleothem-drip water monitoring from two caves within the Austrian and Italian Alps. At Obir cave, Austria, DSO4 (×105) varies between 11.1 (winter) and 9.0 (summer) and the corresponding figures for Ernesto cave, Italy, are 15.4 (winter) and 14

  14. Regolith formation rate from U-series nuclides: Implications from the study of a spheroidal weathering profile in the Rio Icacos watershed (Puerto Rico)

    Science.gov (United States)

    Chabaux, F.; Blaes, E.; Stille, P.; di Chiara Roupert, R.; Pelt, E.; Dosseto, A.; Ma, L.; Buss, H. L.; Brantley, S. L.

    2013-01-01

    A 2 m-thick spheroidal weathering profile, developed on a quartz diorite in the Rio Icacos watershed (Luquillo Mountains, eastern Puerto Rico), was analyzed for major and trace element concentrations, Sr and Nd isotopic ratios and U-series nuclides (238U-234U-230Th-226Ra). In this profile a 40 cm thick soil horizon is overlying a 150 cm thick saprolite which is separated from the basal corestone by a ˜40 cm thick rindlet zone. The Sr and Nd isotopic variations along the whole profile imply that, in addition to geochemical fractionations associated to water-rock interactions, the geochemical budget of the profile is influenced by a significant accretion of atmospheric dusts. The mineralogical and geochemical variations along the profile also confirm that the weathering front does not progress continuously from the top to the base of the profile. The upper part of the profile is probably associated with a different weathering system (lateral weathering of upper corestones) than the lower part, which consists of the basal corestone, the associated rindlet system and the saprolite in contact with these rindlets. Consequently, the determination of weathering rates from 238U-234U-230Th-226Ra disequilibrium in a series of samples collected along a vertical depth profile can only be attempted for samples collected in the lower part of the profile, i.e. the rindlet zone and the lower saprolite. Similar propagation rates were derived for the rindlet system and the saprolite by using classical models involving loss and gain processes for all nuclides to interpret the variation of U-series nuclides in the rindlet-saprolite subsystem. The consistency of these weathering rates with average weathering and erosion rates derived via other methods for the whole watershed provides a new and independent argument that, in the Rio Icacos watershed, the weathering system has reached a geomorphologic steady-state. Our study also indicates that even in environments with differential

  15. Time-scales of erosion and weathering processes in the Himalayan river system: Element and isotope approach using the U-series

    International Nuclear Information System (INIS)

    Granet, M.

    2007-06-01

    The time-scales of erosion and weathering processes are key parameters which need to be determined to understand the response of the reliefs to external forcing like tectonics, climate and human activities. They were recovered by using U-series nuclides analyzed in sediments and suspended materials carried by the Himalayan rivers of the Ganges and Brahmaputra basins. In the Ganges basin, the time-scales of weathering determined from the study of coarse sediments carried by the Kali Gandaki range from several ky, where the uplift is located, to 350 ky. Such values indicate that the bed-rocks are in situ weathered for a long period before the weathering residual products get transported in the rivers as coarse sediments. At the outlet of the high range, these sediments are carried by the tributaries of the Ganges, the Gandak and Ghaghara, during a transfer period of about 100 ka. The study of the sediments at the outlet of the Brahmaputra tributaries allows to propose time-scales of weathering ranging from 110 to 270 ky. Such long periods confirm that during their transfer in the plains, the sediments are temporarily trapped at several places in the basins. In the Ganges and Brahmaputra rivers, the time-scales of sedimentary transfer are 575 and 160 ky, respectively. These values, which are of the same order as their response times, are much longer than the timescales of the Quaternary climate oscillations. It confirms the buffering action of the asiatic alluvial plains for the high-frequency sediment flux variations in response to external forcing in the chain. The study of suspended materials suggests that their chemical compositions result from the mixing of coarse river sediments with fine particles from various locations in the basin which are affected by vegetation recycling. By contrast to coarse sediments, the time-scales of transfer for the suspended materials are fast, e.g. a few ky, pointing the potential of U-series nuclides to assess particle transport

  16. Barite mineralization in Kalana speleothems, Central Estonia: Sr, S and O isotope characterization

    Directory of Open Access Journals (Sweden)

    Mikk Gaškov

    2017-06-01

    Full Text Available Barite mineralization in association with calcitic speleothem precipitates in cave structures in Silurian Aeronian carbonate rocks in Kalana quarry, Central Estonia, was studied. Barite mineralization in Kalana occurs in two generations – euhedral bladed-tabular barite zonal crystals from a few to 10 cm in size, growing on the limestone-dolomite wall-rock (generation I, and sparsely placed thin tabular crystals a few millimetres thick and up to 1 cm in size, growing on calcitic crusts (generation II. The barite crystals of generation I are frequently found embedded by paragenetically later calcitic botryoidal crusts. The Sr and S isotopic composition of barite crystals shows a trend of increasing Sr isotope ratios (from 0.7114 to 0.7120 and δ34S values (from 13‰ to 33‰ from the central parts towards the edges of zonal crystals. This suggests barite precipitation by mixing of two endmember fluids at varying ratios during barite formation: warm (up to 70 °C reducing fluid bearing Ba, characterized by an elevated radiogenic Sr- and 34S-enriched isotopic signal, and a cooler ambient fluid bearing an isotopically lighter dissolved sulphate, characterized by lower Sr isotope ratios. The excess of radiogenic 87Sr in barite compared to Phanerozoic seawater values suggests Sr derived from a continental source, whereas sulphate was derived either from oxidized H2S or a modified seawater source. Gradual increase in δ34S values towards the outer zones could also indicate the 34S enrichment due to bacterial sulphate reduction, even though there is no paired 34S and 18O enrichment of sulphate, characteristic of bacterial reworking. This can be interpreted as indicating an open system with limited sulphate resupply where the δ18O composition of sulphate was equilibrated with warm ascending hydrothermal fluid.

  17. Evaluation of the 'amount effect' at speleothem sites in the Asian monsoon region

    International Nuclear Information System (INIS)

    Lee, Jung-Eun; Swann, Abigail L

    2010-01-01

    Oxygen isotope measurements from speleothems have been used to infer past hydrological cycles because the isotopic composition of precipitation is observed to decrease with increasing precipitation rates over low latitude coastal and island stations (the 'amount effect'). Here we show that local precipitation amount can be inferred from the differences in oxygen isotopic composition if the measurement site is in a subtropical coastal region where water vapor is transported directly from the ocean. The amount effect works because vapor from local evaporation and vapor imported from other regions have distinctly different isotopic compositions - the δ 18 O of vapor flux from evaporation is ∼10 per mille higher than the δ 18 O of imported vapor over subtropical oceanic regions - and precipitation is usually higher over the area with larger convergence. Thus, δ 18 O in precipitation can differentiate between the contribution of local evaporation and moisture convergence if the isotopic composition of local evaporation and or transported vapor remains relatively constant. Our work indicates that sites further inland may not be suitable for studying the changes in local precipitation amount but still reflect the combined changes of precipitation amount and changes in vapor transport pattern. We have shown that Hulu Cave is a reasonable site to interpret precipitation from δ 18 O p : estimated precipitation difference between present-day and Last Glacial Maximum (LGM) from measured δ 18 O p difference (1∼2 per mille ) would be 0.8-2.2 mm/day (lower during the LGM) assuming our model simulates evapotranspiration reasonably well at this site.

  18. New dates reignite human evolution debate

    International Nuclear Information System (INIS)

    Nolch, G.

    2000-01-01

    Australian research into the Asian fossil record is unearthing controversial evidence with implications for the evolution of humans. Dr Jian-xin Zhao and Prof Ken Collerson from the University of Queensland's Department of Earth Sciences have been studying the fossil record in East Asia for clues to the early migration of hominids out of Africa in collaboration with Chinese archaeologists Dr Kai Hu of Nanjing University and Hankui Xu of Nanjing Institute of Palaeontology, Academia Sinica. Together they have been studying the remains of Nanjing Man, the name given to two Homo erectus skulls and the tooth of a third individual discovered in Tangshan Cave 250 km north-west of Shanghai. Dr Zhao and Prof Collerson have now employed more accurate dating techniques and materials, using a mass spectrometer to analyse the amounts of thorium-230 and uranium-234 in a calcite flowstone above the Nanjing Man fossil bed. Unlike fossil teeth, uranium and thorium became locked into the flowstone's crystal lattice when the calcite became crystallised. Because of this, the U-series decay in the calcite reliably records when the calcite crystallised. Taking into account the half-lives of uranium-234 and thorium-230, Dr Zhao and Prof Collerson determined the age of the calcite flowstone to be 577,000 years old (+44,000/-34,000 years). As the flowstone overlies the fossil bed, this date only defines the minimum age of the Nanjing Man fossil bed. For comparison, the dentine and enamel components of one fossil deer tooth collected from the Nanjing Man fossil bed yielded discordant mass spectrometric U-series ages of 388,000 and 130,100 years, respectively. Dr Zhao says that this 'strongly demonstrates the unreliability of fossil teeth as a chronometer'. Other evidence in the sediments surrounding the fossils has been the presence of flora and fauna that are typical of a glacial period. Dr Zhao therefore believes that the skulls could have been deposited during a glacial period

  19. The role of skeletal micro-architecture in diagenesis and dating of Acropora palmata

    Science.gov (United States)

    Tomiak, P. J.; Andersen, M. B.; Hendy, E. J.; Potter, E. K.; Johnson, K. G.; Penkman, K. E. H.

    2016-06-01

    Past variations in global sea-level reflect continental ice volume, a crucial factor for understanding the Earth's climate system. The Caribbean coral Acropora palmata typically forms dense stands in very shallow water and therefore fossil samples mark past sea-level. Uranium-series methods are commonly used to establish a chronology for fossil coral reefs, but are compromised by post mortem diagenetic changes to coral skeleton. Current screening approaches are unable to identify all altered samples, whilst models that attempt to correct for 'open-system' behaviour are not applicable across all diagenetic scenarios. In order to better understand how U-series geochemistry varies spatially with respect to diagenetic textures, we examine these aspects in relation to skeletal micro-structure and intra-crystalline amino acids, comparing an unaltered modern coral with a fossil A. palmata colony containing zones of diagenetic alteration (secondary overgrowth of aragonite, calcite cement and dissolution features). We demonstrate that the process of skeletogenesis in A. palmata causes heterogeneity in porosity, which can account for the observed spatial distribution of diagenetic features; this in turn explains the spatially-systematic trends in U-series geochemistry and consequently, U-series age. We propose a scenario that emphasises the importance of through-flow of meteoric waters, invoking both U-loss and absorption of mobilised U and Th daughter isotopes. We recommend selective sampling of low porosity A. palmata skeleton to obtain the most reliable U-series ages. We demonstrate that intra-crystalline amino acid racemisation (AAR) can be applied as a relative dating tool in Pleistocene A. palmata samples that have suffered heavy dissolution and are therefore unsuitable for U-series analyses. Based on relatively high intra-crystalline concentrations and appropriate racemisation rates, glutamic acid and valine are most suited to dating mid-late Pleistocene A. palmata

  20. Speleothem carbon isotopes in the tropics: a proxy for vegetation and what they reveal about the demise of Homo floresiensis

    Science.gov (United States)

    Scroxton, N.; Gagan, M. K.; Ayliffe, L. K.; Hellstrom, J.; Cheng, H.; Edwards, R.; Zhao, J.; Hantoro, W. S.; Rifai, H.; Scott-Gagan, H.; Cowley, J. A.; Suwargadi, B. W.

    2013-12-01

    Most long-term speleothem climate records focus on δ18O (Cruz Jr. et al. 2005, Wang et al. 2005, Meckler et al. 2012, Carolin et al. 2013). In tropical regions, where temperature variability is relatively small, speleothem δ18O serves as a proxy for precipitation amount. On orbital timescales, changes in moisture source, sea level and global ice volume also influence speleothem δ18O. As both δ18O and δ13C are measured simultaneously, a wealth of potential paleoclimatic information from the δ13C records for numerous sites awaits publication. However, δ13C is less well understood as an environmental proxy, and a simple control and explanation may not be forthcoming. We present a new 92,000-year long speleothem δ13C record for Liang Luar cave in Flores, Indonesia. Here, δ13C acts as a proxy for soil CO2 production above the cave, which is strongly linked to vegetative changes. Since vegetation and soil CO2 production are closely linked to a climatic control, changes in speleothem δ13C can be considered an environmental response to climate change. The Liang Luar δ13C record mainly tracks the δ18O, indicating close affiliation between vegetation and climate. Peak vegetation cover and soil activity (lower δ13C) occur in the early Holocene. The Last Glacial Maximum does not have notably higher δ13C than Isotope Stages 3 and 5a. δ13C variability in the glacial is much higher than that in the Holocene. Differences between the δ13C and δ18O records indicate periods of vegetative change without a climatic cause. The largest increase in δ13C (8‰) during the last 90kyr occurred at 68kyr BP. This anomalous δ13C excursion represents a major loss of vegetation around Liang Luar. The last surviving non-human member of the Homo genus: Homo floresiensis, disappeared from the stratigraphic record in nearby Liang Bua cave between 17 and 10kyr BP (Roberts et al. 2009). The cause of the disappearance, (e.g. climate change, volcanic catastrophe or human competition

  1. Comparison of 14C and U-Th ages of two Holocene phreatic overgrowths on speleothems from Mallorca (Western Mediterranean: Environmental implications

    Directory of Open Access Journals (Sweden)

    Tuccimei Paola

    2011-01-01

    Full Text Available This investigation reports on the comparison between ICP-MS U-Th and AMS 14C ages of Phreatic Overgrowths on Speleothems (POS from two different caves on the island of Mallorca (Spain. These speleothem encrustations form at the water table of coastal caves in a low-amplitude tide-controlled microenvironment and are used to reconstruct past sea level changes. The aim of this study is to evaluate if this particular type of speleothem is datable using 14C method and to investigate possible problems connected with the incorporation of dead carbon inherited from the dissolution of 14C-free limestone. The results show that 14C ages are strongly site dependent and appear related to local residence time of water infiltration through the soil and epikarst. When short transit time and limited interaction with soil and bedrock, as in Cova de Cala Varques A, the so-called “reservoir” effect is negligible and 14C and U-Th ages corresponds within the error range. When the residence time is longer, as in Cova des Pas de Vallgornera, 14C ages are steadily 2,300-2,400 years older than the U-Th data, as shown by the mean value (25% of estimated percent dead carbon proportions and by higher and better correlated contents of major and trace elements in the vadose support of this speleothem encrustation. The potential use of this multi-method approach to paleoenvironmental studies is also suggested.

  2. Oxygen isotopic stratigraphy as a tool for chronology establishing of early and Middle Pleistocene speleothems - a case study from Gleboka Cave (Kraków-Czestochowa Upland, Poland

    Czech Academy of Sciences Publication Activity Database

    Blaszczyk, M.; Hercman, H.; Pawlak, J.; Gasiorowski, M.; Matoušková, Šárka; Aninowska, M.; Kicinska, D.; Tyc, A.

    2017-01-01

    Roč. 22, č. 2 (2017) ISSN 1335-213X. [Vedecká konferencia „Výskum, využívanie a ochrana jaskýň“ /11./. 25.09.2017-26.09.2017, Liptovský Mikuláš] Institutional support: RVO:67985831 Keywords : speleothems * Pleistocene * Gleboka Cave Subject RIV: DB - Geology ; Mineralogy

  3. Understanding Teen Dating Violence

    Science.gov (United States)

    Understanding Teen Dating Violence Fact Sheet 2014 Dating violence is a type of intimate partner violence. It occurs between two people in a close relationship. The nature of dating violence can be physical, emotional, or sexual. • Physical— This ...

  4. Teen Dating Violence

    Science.gov (United States)

    ... Room Social Media Publications Injury Center Teen Dating Violence Recommend on Facebook Tweet Share Compartir On This ... serious forms of violence. What is teen dating violence? Teen Dating Violence [550 KB, 2 Pages, 508] ...

  5. Mid- to late Holocene Indian Ocean Monsoon variability recorded in four speleothems from Socotra Island, Yemen

    Science.gov (United States)

    Van Rampelbergh, Maïté; Fleitmann, Dominik; Verheyden, Sophie; Cheng, Hai; Edwards, Lawrence; De Geest, Peter; De Vleeschouwer, David; Burns, Stephen J.; Matter, Albert; Claeys, Philippe; Keppens, Eddy

    2013-04-01

    Four stalagmites covering the last 7.0 ka were sampled on Socotra, an island in the northern Indian Ocean to investigate the evolution of the northeast Indian Ocean Monsoon (IOM) since the mid Holocene. On Socotra, rain is delivered at the start of the southwest IOM in May-June and at the start of the northeast IOM from September to December. The Haggeher Mountains act as a barrier forcing precipitation brought by the northeast winds to fall preferentially on the eastern side of the island, where the studied caves are located. δ18O and δ13C and Mg/Ca and Sr/Ca signals in the stalagmites reflect precipitation amounts brought by the northeast winds. For stalagmite STM6, this amount effect is amplified by kinetic effects during calcite deposition. Combined interpretation of the stalagmites' signals suggest a weakening of the northeast precipitation between 6.0 and 3.8 ka. After 3.8 ka precipitation intensities remain constant with two superimposed drier periods, between 0 and 0.6 ka and from 2.2 to 3.8 ka. No link can be established with Greenland ice cores and with the summer IOM variability. In contrast to the stable northeast rainy season suggested by the records in this study, speleothem records from western Socotra indicate a wettening of the southwest rainy season on Socotra after 4.4 ka. The local wettening of western Socotra could relate to a more southerly path (more over the Indian Ocean) taken by the southwest winds. Stalagmite STM5, sampled at the fringe between both rain areas displays intermediate δ18O values. After 6.2 ka, similar precipitation changes are seen between eastern Socotra and northern Oman indicating that both regions are affected similarly by the monsoon. Different palaeoclimatologic records from the Arabian Peninsula currently located outside the ITCZ migration pathway display an abrupt drying around 6 ka due to their disconnection from the southwest rain influence. Records that are nowadays still receiving rain by the southwest winds

  6. Progress in radiocarbon dating

    International Nuclear Information System (INIS)

    Hedges, R.E.M.

    1985-01-01

    The article concerns radiocarbon dating, the most important method for dating in archaeology. The principles and practice of the dating method are described. Recent developments in radiocarbon dating due to technical advances, are discussed, and include radiometric counting of small samples and accelerator mass spectrometry. Carbon isotopes and the environment are also discussed. (U.K.)

  7. Biomineralization and biosignatures of coralloid-type speleothems from lava tubes of Galapagos Islands: evidences on the fossil record of prokaryotes

    Science.gov (United States)

    Miller, Ana Z.; Garcia-Sanchez, Angela M.; Pereira, Manuel F. C.; Gazquez, Fernando; Calaforra, José M.; Forti, Paolo; Toulkeridis, Theofilos; Martínez-Frías, Jesús; Saiz-Jimenez, Cesareo

    2016-04-01

    Lava tubes have traditionally been considered of little interest from a mineralogical point of view. Recently, this type of volcanic caves has received particular attention because lava tubes have been described on Mars. Speleothems, or secondary mineral deposits in lava tubes are mainly composed of siliceous minerals. Coralloid-type speleothems are found either on basaltic cave walls or on the surface of other speleothems. Several authors attribute a microbially mediated origin to their formation. This type of speleothems was recorded within Royal Palm Cave of Santa Cruz Island in Galapagos Archipelago (Ecuador), a lava tube 600 m long, 5 to 15 m height and 2 to 10 m width. The Galapagos Islands are an archipelago of 19 volcanic islands located some 1500 km west of Ecuador, in the Pacific Ocean. These islands host one of the most biodiverse settings on Earth, studied by Charles Darwin. Beige and greyish small coralloids were collected in Royal Palm Cave and analysed by field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDS), X-ray micro-computed tomography (micro-CT) and mineralogical analyses for morphological, 3D microstructural and compositional characterization, as well as for assessing microbe-mineral interactions and biogenicity. In addition, 16S rRNA gene analyses were performed to identify microbial communities associated with the coralloid-type speleothems. The coralloids showed internal compositional zonation along the growth direction of the speleothems, according to micro-CT data. Internal layering was clearly discernable by the differences in opacity of the distinct mineralogical phases to X-rays, being dominated by alteration products of siliceous composition, whereas more opaque phases, usually Ca-rich minerals, were dominant in the outermost part of the speleothems. X-ray diffraction and infrared spectroscopy reinforced that the first stage of deposition is mainly composed of opal A and clay minerals

  8. Carbon dioxide concentration in caves and soils in an alpine setting: implications for speleothem fabrics and their palaeoclimate significance

    Science.gov (United States)

    Borsato, Andrea; Frisia, Silvia; Miorandi, Renza

    2015-04-01

    Carbon dioxide concentration in soils controls carbonate dissolution, soil CO2 efflux to the atmosphere, and CO2 transfer to the subsurface that lead, ultimately, to speleothem precipitation. Systematic studies on CO2 concentration variability in soil and caves at regional scale are, however, few. Here, the systematic investigation of CO2 concentration in caves and soils in a temperate, Alpine region along a 2,100 m altitudinal range transect, which corresponds to a mean annual temperature (MAT) range of 12°C is presented. Soil pCO2 is controlled by the elevation and MAT and exhibits strong seasonality, which follows surface air temperature with a delay of about a month. The aquifer pCO2, by contrast, is fairly constant throughout the year, and it is primarily influenced by summer soil pCO2. Cave CO2 concentration is a balance between the CO2 influx and CO2 efflux, where the efflux is controlled by the cave ventilation, which is responsible for low pCO2 values recorded in most of the caves with respect to soil levels. Carbon dioxide in the innermost part of the studied caves exhibits a clear seasonal pattern. Thermal convection is the most common mechanism causing higher ventilation and low cave air pCO2 levels during the winter season: this promotes CO2 degassing and higher supersaturation in the drip water and, eventually, higher speleothem growth rates during winter. The combined influence of three parameters - dripwater pCO2, dripwater Ca content, and cave air pCO2 - all related to the infiltration elevation and MAT directly controls calcite supersaturation in dripwater. Four different altitudinal belts are then defined, which reflect temperature-dependent saturation state of dripwaters. These belts broadly correspond to vegetation zones: the lower montane (100 to 800 m asl), the upper montane (800 to 1600 m asl), the subalpine (1600 to 2200 m asl) and the Alpine (above 2200 m asl). Each altitudinal belt is characterised by different calcite fabrics, which can

  9. Paleoclimatic features in Central Japan based on the stable isotope compositions of Lake Biwa sediments and speleothems

    International Nuclear Information System (INIS)

    Nakai, Nobuyuki; Shirai, Yasutoshi

    1978-01-01

    In this paper, the climatic fluctuation of Japanese Island in the past deduced from the carbon isotope study of Lake Biwa sediments is discussed in connection with the vertical profile of fossil diatom numbers, climate estimated by palynological studies, and paleogeomagnetic polarity change for the same core samples. In addition to the climatic studies that have used the Lake sediments, the climatic change measured in detail by O 18 /O 16 ratios of speleothem CaCO 3 is reported for the past 37 x 10 3 years. Sediment samples for C 13 /C 12 analyses were taken at intervals of 5 m from the cored column of 200 m length. Stalactite and flowstone samples were collected from Otaki Cave, Gifu Prefecture, near Lake Biwa. The isotopic data for both carbon and oxygen are presented as per mil deviation from the PDB and SMOW standards, respectively. The Δ C 13 values of organic C are plotted in relation to the number of total diatom cells. The figure shows no correlation between them. The Δ C 13 values of sedimentary organic C and the past productivity of the lake have different linear relation in each different period. The present authors tried to calculate directly the deposition temperature by a method different from Hendy's. The Δ O 18 values of the water passing through the speleothem surface in the past are determined by those of rain water in the region. The calculated temperatures range from 10.6 to 15.0 deg. C. By connecting the results obtained from two flowstones and a stalactite, a paleotemperature curve can be drawn for the last 37 x 10 3 years. (Kato, T

  10. Precise oxygen and hydrogen isotope determination in nanoliter quantities of speleothem inclusion water by cavity ring-down spectroscopic techniques

    Science.gov (United States)

    Uemura, Ryu; Nakamoto, Masashi; Asami, Ryuji; Mishima, Satoru; Gibo, Masakazu; Masaka, Kosuke; Jin-Ping, Chen; Wu, Chung-Che; Chang, Yu-Wei; Shen, Chuan-Chou

    2016-01-01

    Speleothem inclusion-water isotope compositions are a promising new climatic proxy, but their applicability is limited by their low content in water and by analytical challenges. We have developed a precise and accurate isotopic technique that is based on cavity ring-down spectroscopy (CRDS). This method features a newly developed crushing apparatus, a refined sample extraction line, careful evaluation of the water/carbonate adsorption effect. After crushing chipped speleothem in a newly-developed crushing device, released inclusion water is purified and mixed with a limited amount of nitrogen gas in the extraction line for CRDS measurement. We have measured 50-260 nL of inclusion water from 77 to 286 mg of stalagmite deposits sampled from Gyokusen Cave, Okinawa Island, Japan. The small sample size requirement demonstrates that our analytical technique can offer high-resolution inclusion water-based paleoclimate reconstructions. The 1σ reproducibility for different stalagmites ranges from ±0.05 to 0.61‰ for δ18O and ±0.0 to 2.9‰ for δD. The δD vs. δ18O plot for inclusion water from modern stalagmites is consistent with the local meteoric water line. The 1000 ln α values based on calcite and fluid inclusion measurements from decades-old stalagmites are in agreement with the data from present-day farmed calcite experiment. Combination of coeval carbonate and fluid inclusion data suggests that past temperatures at 9-10 thousand years ago (ka) and 26 ka were 3.4 ± 0.7 °C and 8.2 ± 2.4 °C colder than at present, respectively.

  11. Paleoclimatological revision of climate evolution in Spain since the middle pleistocene from travertine and speleothems studies; Aportaciones al conociiento de la evolucion paleoclimatica y paleoambiental en la pensinsula iberica durante los dos ultimos millones de anos a partir del estudio de travertinos y espeleotemas

    Energy Technology Data Exchange (ETDEWEB)

    Torres, T; Barettino, D; Canoira, L; Cobo, R; Garcia-Cortes, A; Grun, R; Hoyos, M; Julia, R; Llamas, R

    1996-10-01

    This paper deals on the main results of the Project: ``Paleoclimatological revision since the Middle Pleistocene from geochronological and isotope analysis of spanish travertine`` (CEC-F12W-CT91-0075 ``Paleoclimatological revision of climate evolution in the Western Mediterranean Region, evaluation of altered scenarios). Four travertine deposition areas and a karstic zone were selected according to their geographical signification. Travertine deposits areas were: Priego and Rio Blanco: fluvial travertine; Banyoles and Rio Blanco: lacustrine deposits; Tolox: Alluvial fan deposits. The Cueva del Reguerillo was the karstic area selected. In spite of travertine and speleothems are warm climate indicators, important paleoenvironmental and palaeoclimatological data were obtained, which are in short: Through geomorphology and dating (palaeomagnetism, U/Th, Electro spin resonance and amino acid racemization analysis) the fluvial history of Priego, Rio Blanco and el Reguerillo cave, where a neotectonic and palaeosismicity phenomena were also dated. The oldest ESR dating method age obtained was of 950ka; and the oldest Priego deposits AARD dated were 750 ka old. Through dating, sedimentology, stable isotope analysis and palinology some aspects of climatic evolution of the Iberian Peninsula were determined. A net correlation found between palinology and stable isotope ratios in the Banyoles lake drill hole, allowed to validate the results. Some cualitative data on fluvial and karstic systems water input were determined also.

  12. Role of radiation dating technique - one example

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Shigueo [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Etchevarne, Carlos A. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Fac. de Filosofia e Ciencias Humanas. Dept. Antropologia e Etnologia; Cano, Nilo F.; Munita, C.S. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-07-01

    Full text: The great majority of archaeological or geological dating technique is based on radiation effect. The so called radioactivity method uses radioactive decays of elements. This is the case of the well known radiocarbon or carbon-14 method. Also the method of relating daughter nucleus to decaying nucleus, as in K-40/Ar-40, Th- 230/U-234, etc. Here we will concentrate in the method based on energy deposition in a solid by radiation from the disintegration of U-series and Th-series. {beta}-rays emitted by the decay of K-40 into Ca-40 (80%) and Ar-40 (11%) also contributes. The role of {alpha}, {beta} and {gamma} radiation emitted by radionuclides in the U-238 and Th-232 series and of {beta} rays from the decay of K-40, all of them in the soil irradiate anything in their course. For dating, we can have sediments as well as potteries produced by ancient people and became buried. The important process consists in transferring a fraction of the energy of radiation to the solid, mainly liberating electrons from valence band to conduction band and from there to traps. In many case the energy of the radiation is used to create defects which in turn create energy levels (traps) in the forbidden gap (or energy gap). There are three ways to recover the energy stored in the solid: (1) by emission of light optically stimulated (OSL), (2) by emission of light thermally stimulated (TL), (3) by microwave absorption (EPR or ESR). Using these techniques among several applications, we will present one to find the first settlers in the northeaster region of Brazil. (author)

  13. Role of radiation dating technique - one example

    International Nuclear Information System (INIS)

    Watanabe, Shigueo

    2012-01-01

    Full text: The great majority of archaeological or geological dating technique is based on radiation effect. The so called radioactivity method uses radioactive decays of elements. This is the case of the well known radiocarbon or carbon-14 method. Also the method of relating daughter nucleus to decaying nucleus, as in K-40/Ar-40, Th- 230/U-234, etc. Here we will concentrate in the method based on energy deposition in a solid by radiation from the disintegration of U-series and Th-series. β-rays emitted by the decay of K-40 into Ca-40 (80%) and Ar-40 (11%) also contributes. The role of α, β and γ radiation emitted by radionuclides in the U-238 and Th-232 series and of β rays from the decay of K-40, all of them in the soil irradiate anything in their course. For dating, we can have sediments as well as potteries produced by ancient people and became buried. The important process consists in transferring a fraction of the energy of radiation to the solid, mainly liberating electrons from valence band to conduction band and from there to traps. In many case the energy of the radiation is used to create defects which in turn create energy levels (traps) in the forbidden gap (or energy gap). There are three ways to recover the energy stored in the solid: (1) by emission of light optically stimulated (OSL), (2) by emission of light thermally stimulated (TL), (3) by microwave absorption (EPR or ESR). Using these techniques among several applications, we will present one to find the first settlers in the northeaster region of Brazil. (author)

  14. Preservation of NOM-metal complexes in a modern hyperalkaline stalagmite: Implications for speleothem trace element geochemistry

    Science.gov (United States)

    Hartland, Adam; Fairchild, Ian J.; Müller, Wolfgang; Dominguez-Villar, David

    2014-03-01

    We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM-metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (δ18O and δ13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ˜11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace element variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7-8. We find that NOM-metal(aq) complexes on the boundary between colloidal and dissolved (˜1 nm diameter) show an annual cyclicity which is inversely correlated with the alkaline earth metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM-metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (Kd) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace element to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (fm). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic Kd values and field measurements for metal partitioning into calcite occur where [free metal] ≪ [total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where fm ≈ 0, apparent inorganic Kd app values are also ≈0, but the

  15. Correlates of minimal dating.

    Science.gov (United States)

    Leck, Kira

    2006-10-01

    Researchers have associated minimal dating with numerous factors. The present author tested shyness, introversion, physical attractiveness, performance evaluation, anxiety, social skill, social self-esteem, and loneliness to determine the nature of their relationships with 2 measures of self-reported minimal dating in a sample of 175 college students. For women, shyness, introversion, physical attractiveness, self-rated anxiety, social self-esteem, and loneliness correlated with 1 or both measures of minimal dating. For men, physical attractiveness, observer-rated social skill, social self-esteem, and loneliness correlated with 1 or both measures of minimal dating. The patterns of relationships were not identical for the 2 indicators of minimal dating, indicating the possibility that minimal dating is not a single construct as researchers previously believed. The present author discussed implications and suggestions for future researchers.

  16. Dating of cremated bones

    OpenAIRE

    Lanting, JN; Aerts-Bijma, AT; van der Plicht, J; Boaretto, E.; Carmi, I.

    2001-01-01

    When dating unburnt bone, bone collagen, the organic fraction of the bone, is used. Collagen does not survive the heat of the cremation pyre, so dating of cremated bone has been considered impossible. Structural carbonate in the mineral fraction of the bone, however, survives the cremation process. We developed a method of dating cremated bone by accelerator mass spectrometry (AMS), using this carbonate fraction. Here we present results for a variety of prehistoric sites and ages, showing a r...

  17. Carbon 14 dating method

    International Nuclear Information System (INIS)

    Fortin, Ph.

    2000-01-01

    This document gives a first introduction to 14 C dating as it is put into practice at the radiocarbon dating centre of Claude-Bernard university (Lyon-1 univ., Villeurbanne, France): general considerations and recalls of nuclear physics; the 14 C dating method; the initial standard activity; the isotopic fractioning; the measurement of samples activity; the liquid-scintillation counters; the calibration and correction of 14 C dates; the preparation of samples; the benzene synthesis; the current applications of the method. (J.S.)

  18. Irradiation of dates

    International Nuclear Information System (INIS)

    Farkas, J.; Al-Charchafchy, F.; Al-Shaikhaly, M.H.; Mirjan, J.; Auda, H.

    1974-01-01

    Testing of the technical feasibility of radurization of fresh dates was attempted. In addition preliminary studies were carried out to investigate the applicability of gamma rays to date syrup manufacture. The varieties Zahdi, Lelwi and Tabarzel were studied at different stages of ripening. The eating quality of fresh dates was not affected significantly by irradiation even with doses of 270 and 540 krad. The duration of the softening process, after-ripening, of dates was prolonged by low doses of 10-30 krad in the majority of the experimental batches. The time period of after-ripening was reduced with 270 krad, as well as with 540 krad as a result of shortening of the induction period, i.e. the time after which the date begins to soften. The microbial spoilage of khalaal Lelwi dates was considerably reduced by irradiation with doses above 90 krad. The dibis yield of fully rutab dates was highly increased by the radiation doses of 375 to 2000 krad. The darkness and viable cell count of dibis pressed from irradiated dates were significantly lower than that of untreated dates. (F.J.)

  19. Pleistocene apparent ages by U-Pb isotope and U-series methods for uranium ore in Dakota Sandstone near Gallup, New Mexico

    International Nuclear Information System (INIS)

    Ludwig, K.R.; Szabo, B.J.; Granger, H.C.

    1977-01-01

    Radiometric dates of a high-grade uranium ore from the Hogback No. 4 mine in Dakota Sandstone near Gallup, N. Mex., indicate a late Pleistocene age of mineralization. The 206 Pb/ 238 U and 207 Pb/ 235 U apparent ages of about 70,000 y and 100,000 y, respectively, are discordant, but are in broad agreement with the discordant 230 Th/ 238 U and 230 Pa/ 235 U apparent ages of 130,000 y and 78,000 y, respectively. Although it is not clear how the analyzed sample relates to the main period of mineralization at this mine, these dates are consistent with previous age limits suggested for Dakota Sandstone uranium ores

  20. Constraining the subsoil carbon source to cave-air CO2 and speleothem calcite in central Texas

    Science.gov (United States)

    Bergel, Shelly J.; Carlson, Peter E.; Larson, Toti E.; Wood, Chris T.; Johnson, Kathleen R.; Banner, Jay L.; Breecker, Daniel O.

    2017-11-01

    Canonical models for speleothem formation and the subsurface carbon cycle invoke soil respiration as the dominant carbon source. However, evidence from some karst regions suggests that belowground CO2 originates from a deeper, older source. We therefore investigated the carbon sources to central Texas caves. Drip-water chemistry of two caves in central Texas implies equilibration with calcite at CO2 concentrations (PCO2_sat) higher than the maximum CO2 concentrations observed in overlying soils. This observation suggests that CO2 is added to waters after they percolate through the soils, which requires a subsoil carbon source. We directly evaluate the carbon isotope composition of the subsoil carbon source using δ13C measurements on cave-air CO2, which we independently demonstrate has little to no contribution from host rock carbon. We do so using the oxidative ratio, OR, defined as the number of moles of O2 consumed per mole of CO2 produced during respiration. However, additional belowground processes that affect O2 and CO2 concentrations, such as gas-water exchange and/or diffusion, may also influence the measured oxidative ratio, yielding an apparent OR (ORapparent). Cave air in Natural Bridge South Cavern has ORapparent values (1.09 ± 0.06) indistinguishable from those expected for respiration alone (1.08 ± 0.06). Pore space gases from soils above the cave have lower values (ORapparent = 0.67 ± 0.05) consistent with respiration and gas transport by diffusion. The simplest explanation for these observations is that cave air in NB South is influenced by respiration in open-system bedrock fractures such that neither diffusion nor exchange with water influence the composition of the cave air. The radiocarbon activities of NB South cave-air CO2 suggest the subsoil carbon source is hundreds of years old. The calculated δ13C values of the subsoil carbon source are consistent with tree-sourced carbon (perhaps decomposing root matter), the δ13C values of which

  1. S K Date

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science. S K Date. Articles written in Bulletin of Materials Science. Volume 23 Issue 2 April 2000 pp 97-101 Magnetic Materials. Comparison of the irreversible thermomagnetic behaviour of some ferro- and ferrimagnetic systems · P S Anil Kumar P A Joy S K Date · More Details Abstract ...

  2. Second Quaternary dating workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The second Quaternary dating methods workshop was held at Lucas Heights and sponsored by ANSTO and AINSE. Topics covered include, isotope and thermoluminescence dating, usage of accelerator and thermal ionisation mass spectrometry in environmental studies emphasizing on the methodologies used and sample preparation

  3. Dating of cremated bones

    NARCIS (Netherlands)

    Lanting, JN; Aerts-Bijma, AT; van der Plicht, J; Boaretto, E.; Carmi, I.

    2001-01-01

    When dating unburnt bone, bone collagen, the organic fraction of the bone, is used. Collagen does not survive the heat of the cremation pyre, so dating of cremated bone has been considered impossible. Structural carbonate in the mineral fraction of the bone, however, survives the cremation process.

  4. Second Quaternary dating workshop

    International Nuclear Information System (INIS)

    1999-01-01

    The second Quaternary dating methods workshop was held at Lucas Heights and sponsored by ANSTO and AINSE. Topics covered include, isotope and thermoluminescence dating, usage of accelerator and thermal ionisation mass spectrometry in environmental studies emphasizing on the methodologies used and sample preparation

  5. Quaternary faulting in the Tatra Mountains, evidence from cave morphology and fault-slip analysis

    OpenAIRE

    Szczygieł Jacek

    2015-01-01

    Tectonically deformed cave passages in the Tatra Mts (Central Western Carpathians) indicate some fault activity during the Quaternary. Displacements occur in the youngest passages of the caves indicating (based on previous U-series dating of speleothems) an Eemian or younger age for those faults, and so one tectonic stage. On the basis of stress analysis and geomorphological observations, two different mechanisms are proposed as responsible for the development of these displacements. The firs...

  6. Quaternary dating methods

    International Nuclear Information System (INIS)

    Mahaney, W.C.

    1984-01-01

    The papers in this book cover absolute, relative and multiple dating methods, and have been written by specialists from a number of different earth sciences disciplines - their common interest being the dating of geological materials within the Quaternary. Papers on absolute dating methods discuss radiocarbon, uranium-series, potassium argon, 40 Ar/ 39 Ar, paleomagnetic, obsidian hydration, thermoluminescence, amino acid racemization, tree rings, and lichenometric techniques. Those on relative dating include discussions on various geomorphic relative age indicators such as drainage density changes, hypsometric integrals, bifurcation ratios, stream junction angles, spur morphology, hillslope geometry, and till sheet characteristics. The papers on multiple dating cite examples from the Rocky Mountains, Australia, Lake Agassiz Basin, and the Southern Andes. Also included is the panel discussion which reviews and assesses the information presented, and a field trip guide which discusses the sequences of Wisconian tills and interlayered lacustrine and fluvial sediments. (orig.)

  7. Luminescence dating in archaeology

    International Nuclear Information System (INIS)

    Wintle, A.G.

    2001-01-01

    Thermoluminescence (TL) dating is routinely applied to burnt lithic material. Simple fires are capable of enabling stones weighing a few hundred grams to reach 450 o C, thus zeroing the TL signal. TL dates have been obtained for Upper and Lower Paleolithic sites in Europe and the Near East. TL dating continues to be used for dating pottery and for authentification of ceramic works of art. Some recent studies report the use of optically stimulated luminescence (OSL) (also know as photoluminescence) for dating very small samples of quartz, e.g. from small pieces of pottery or frm metallurgical slag The major recent advance has been in the development of a reliable laboratory procedure for using the OSL signal from quartz to obtain the past radiation exposure. The quartz OSL signal is extremely sensitive to light and is reduced to a negligible level on exposure to direct sunlight for radionuclides during burial, signal to date san.sized quartz grains extracted from sediments, The OSL signal is stimulated by 470 nm light from emitting diodes and the detected using flirters centred on 340 nm A similar signal can be obtained from feldspar grain when are exposed to infrared wavelengths around 880 nm. The infrared stimulated luminescence (IRSL) signals is also rapidly depleted by exposure to sunlight, and dating of colluvial deposits from archaeological sites has been reported

  8. Date Rape (For Teens)

    Science.gov (United States)

    ... owe" someone sex, even if you're a couple. Rape is not always violent. If you say " ... date rape" drugs like: rohypnol , called roofies, lunch money, or mind erasers GHB (gamma hydroxybutyric acid), called ...

  9. Methods of dating

    Energy Technology Data Exchange (ETDEWEB)

    Gatty, B

    1986-04-01

    Scientific methods of dating, born less than thirty years ago, have recently improved tremendously. First the dating principles will be given; then it will be explained how, through natural radioactivity, we can have access to the age of an event or an object; the case of radiocarbon will be especially emphasized. The principle of relative methods such as thermoluminescence or paleomagnetism will also be shortly given. What is the use for dating. The fields of its application are numerous; through these methods, relatively precise ages can be given to the major events which have been keys in the history of universe, life and man; thus, dating is a useful scientific tool in astrophysics, geology, biology, anthropology and archeology. Even if certain ages are still subject to controversies, we can say that these methods have confirmed evolution's continuity, be it on a cosmic, biologic or human scale, where ages are measured in billions, millions or thousands of years respectively.

  10. Radiometric dating methods

    International Nuclear Information System (INIS)

    Bourdon, B.

    2003-01-01

    The general principle of isotope dating methods is based on the presence of radioactive isotopes in the geologic or archaeological object to be dated. The decay with time of these isotopes is used to determine the 'zero' time corresponding to the event to be dated. This paper recalls the general principle of isotope dating methods (bases, analytical methods, validation of results and uncertainties) and presents the methods based on natural radioactivity (Rb-Sr, Sm-Nd, U-Pb, Re-Os, K-Ar (Ar-Ar), U-Th-Ra- 210 Pb, U-Pa, 14 C, 36 Cl, 10 Be) and the methods based on artificial radioactivity with their applications. Finally, the methods based on irradiation damages (thermoluminescence, fission tracks, electron spin resonance) are briefly evoked. (J.S.)

  11. NAIP 2012 Image Dates

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — This map is produced by the Aerial Phtography Field Office (APFO) to show the image acquisition dates for the 2012 National Agriculture Imagery Program (NAIP)...

  12. NAIP 2014 Image Dates

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — This map is produced by the Aerial Phtography Field Office (APFO) to show the image acquisition dates for the 2014 National Agriculture Imagery Program (NAIP)...

  13. Food Product Dating

    Science.gov (United States)

    ... Standard Forms FSIS United States Department of Agriculture Food Safety and Inspection Service About FSIS District Offices ... Web Content Viewer (JSR 286) Actions ${title} Loading... Food Product Dating "Best if Used By" is a ...

  14. NAIP 2013 Image Dates

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — This map is produced by the Aerial Phtography Field Office (APFO) to show the image acquisition dates for the 2013 National Agriculture Imagery Program (NAIP)...

  15. NAIP 2011 Image Dates

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — This map is produced by the Aerial Phtography Field Office (APFO) to show the image acquisition dates for the 2011 National Agriculture Imagery Program (NAIP)...

  16. Dating fossil opal phytoliths

    International Nuclear Information System (INIS)

    Lentfer, C.; Boyd, B.; Torrence, R.

    1999-01-01

    Full text: Opal phytoliths are microscopic silica bodies formed by the precipitation of hydrated silica dioxide (SiO 2 nH 2 0) in, around and between cell walls. They are relatively resistant to degradation in most environments and thus, can occur in large quantities in palaeosediments. Consequently, they are valuable tools for environmental reconstruction. Furthermore, phytoliths are often the only recoverable organic material in well oxidised sediments, the occluded carbon provides the opportunity for dating sediment whose ages have previously been difficult to determine, and thus, increase the potential for fine resolution determination of environmental change. This poster describes the results of an investigation assessing the viability of AMS radiocarbon dating of fossil phytolith inclusions using samples from Garua Island, West New Britain, PNG. Thirteen phytolith samples, isolated from sediments previously dated using tephrastratigraphy and C14 dating of macroremains of nutshells and wood charcoal, were used in the analysis. As a control measure, thirteen parallel samples of microscopic charcoal were also dated using AMS. The results show that the AMS dates for the microscopic charcoal samples are consistent with ages anticipated from the other dating methods, for all but one sample. However, the dates for eight of the thirteen phytolith samples are considerably younger than expected. This bias could be explained by several factors, including downwashing of phytolith through soils, bioturbation, carbon exchange through the siliceous matrix of the phytolith bodies, and contamination from extraneous sources of modern carbon retained in the samples. Research is currently focusing on the investigation of these issues and selected samples are in the process of being retreated with strong oxidising agents to clear contaminants prior to re-dating. Further to this, a full investigation of one profile with a long sequence is underway. High concentrations of

  17. Absolute dating and palaeoenvironmental evolution in Palaeolithic Mani, SW Peloponnesus

    Science.gov (United States)

    Christodoulakis, John; Bassiakos, Yannis; Athanassas, Constantin

    2013-04-01

    Data derived from palaeoenvironmental indicators are considered the most reliable in back casting former environmental contexts and also, where possible, in forecasting future trends in the environment. The peninsula of Mani, southern Peloponnesus, southwestern Greece, is a challenging area for studying past environmental changes of the Upper Quaternary, because of its nodal position between three continents, its long and multifarious coastal zone, as well as its active local tectonic regime. A great deal of sea level oscillations and palaeoclimatic and palaeoanthropological evidence have been well-documented in the terrestrial and coastal sedimentery deposits of the peninsula, particularly for the later part of the Quaternary (Kelletat und Gassert, 1975, Imperatori, 1966). That evidence mostly comes from paleoenvironmental indicators such as raised marine notches and marine terraces, as well as from other,indicators, and is frequently associated with sites of paleoanthropological significance An important parameter of those sedimentary deposits is their chronology. To date, the chronological framework of those processes is only loosely constrained. A first effort to produce chronological data for this area was made about twenty years ago by applying electron spin resonance (ESR) dating to speleothems from the local subsurface caverns system and other karst formations. Here, by engaging luminescence dating, we aimed to further control former ESR chronology as well as to extend numeric dating on sedimentary formations previously non-datable through ESR alone (i.e. fluvial/deltaic sediments occurring in the area as well as anthropogenic composite deposits usually including burnt bones and fragments of stone tools). Specifically, optically stimulated luminescence (OSL) dating, combined with the single-aliquot regenerative dose (SAR) protocol, produced a number of ages that are in fair agreement with the previous ESR chronology. Current data allowed us to comprehend

  18. History of radiocarbon dating

    Energy Technology Data Exchange (ETDEWEB)

    Libby, W F [Department of Chemistry and Institute of Geophysics, University of California, Los Angeles, CA (United States)

    1967-08-15

    The development is traced of radiocarbon dating from its birth in curiosity regarding the effects of cosmic radiation on Earth. Discussed in historical perspective are: the significance of the initial measurements in determining the course of developments; the advent of the low-level counting technique; attempts to avoid low-level counting by the use of isotopic enrichment; the gradual appearance of the environmental effect due to the combustion of fossil fuel (Suess effect); recognition of the atmosphere ocean barrier for carbon dioxide exchange; detailed understanding of the mixing mechanism from the study of fallout radiocarbon; determination of the new half-life; indexing and the assimilation problem for the massive accumulation of dates; and the proliferation of measurement techniques and the impact of archaeological insight on the validity of radiocarbon dates. (author)

  19. Variations on seepage water geochemistry induced by natural and anthropogenic microclimatic changes: Implications for the speleothems growth conditions

    Science.gov (United States)

    Fernandez-Cortes, A.; Sanchez-Moral, S.; Canaveras, J. C.; Cuevas, J.; Cuezva, S.; Andreu, J. M.; Abella, R.

    2009-04-01

    During an annual cycle the effect of microclimatic changes (natural and anthropogenic origin) on the geochemical characteristics of seepage water and mineral precipitation rates was analyzed, for two karstic caves under opposing environmental stability and energy exchange with exterior. On the one hand Castañar cave (Caceres, Spain), an extremely controlled show cave with limited visitation showing a minimum exchange rate of energy with the outer atmosphere and, secondly, Canelobre cave (Alicante, Spain), a widely visited cave where the anthropogenic impact generates both high-speed and high-energy environmental changes. Microclimatic variations play a key role in CO2-dessgasing caused by the imbalance of pCO2 between the karstic water and the cave air, favoring the slow processes of mineral precipitation. Thus, a pCO2-range of seepage water have been detected for each cave (from 10-2.30/-2.35 to 10-2.47/-2.52 bar for Castañar cave, and from 10-2.8/-2.85 to 10-2.95/-3.0 bar for Canelobre cave) where the mineral oversaturation prevails, determining the type and rate of mineral precipitation in each cave. Finally, it analyzes how the changes on the oversaturation/ precipitation states are controlled by microclimatic variations, such as: 1) natural underground air renewal through the porous system of upper soil and the network of host-rock fissures (isolating membranes), or else through the cave entrance, 2) cumulative disruptions in the pCO2 levels of cave air due to the presence of visitors, and 3) forced ventilation of the subterranean atmosphere due to the uncontrolled opening of cave entrances. The obtained results reinforce the significance of the microclimatic fluctuations on short time scales in the dynamic and evolution of the subterranean karst system, in terms of rates of mineral precipitation and growth of speleothems. Likewise the interpretations are useful in order to ensure the constant climate required for the conservation of caves.

  20. An isotopic and modelling study of flow paths and storage in Quaternary calcarenite, SW Australia: implications for speleothem paleoclimate records

    Science.gov (United States)

    Treble, Pauline C.; Bradley, Chris; Wood, Anne; Baker, Andy; Jex, Catherine N.; Fairchild, Ian J.; Gagan, Michael K.; Cowley, Joan; Azcurra, Cecilia

    2013-03-01

    We investigated the distinctive shallow sub-surface hydrology of the southwest Western Australia (SWWA) dune calcarenite using observed rainfall and rainfall δ18O; soil moisture, cave drip rate and dripwater δ18O over a six-year period: August 2005-March 2012. A lumped parameter hydrological model is developed to describe water fluxes and drip δ18O. Comparison of observed data and model output allow us to assess the critical non-climatic karst hydrological processes that modify the precipitation δ18O signal and discuss the implications for speleothem paleoclimate records from this cave and those with a similar karst setting. Our findings include evidence of multiple reservoirs, characterised by distinct δ18O values and recharge responses ('low' and 'high' flow sites). Dripwaters exhibit δ18O variations in wet versus dry years at low-flow sites receiving diffuse seepage from the epikarst with an attenuated isotopic composition that approximates mean rainfall. Recharge from high-magnitude rain events is stored in a secondary reservoir which is associated with high-flow dripwater that is 1‰ lower than our monitored low-flow sites (δ18O). One drip site is characterised by mixed-flow behaviour and exhibits a non-linear threshold response after the cessation of drainage from a secondary reservoir following a record dry year (2006). Additionally, our results yield a better understanding of the vadose zone hydrology and dripwater characteristics in Quaternary age dune limestones. We show that flow to our monitored sites is dominated by diffuse flow with inferred transit times of less than one year. Diffuse flow appears to follow vertical preferential paths through the limestone reflecting differences in permeability and deep recharge into the host rock.

  1. Obsidian dating prospects

    International Nuclear Information System (INIS)

    Ambrose, W.

    1997-01-01

    Full text: Developments in the nuclear industry have shown that some of the problems related to the glassification of waste for long term storage are centred on the rate of glass weathering in various repositories. Long term weathering of artificial glasses is paralleled by the archaeological problem of determining hydration rates in obsidian artefacts as a means of dating their manufacture. Figures available for sites in Papua New Guinea indicate that the weathering rate is sufficiently fast to render conventional hydration measurement completely unreliable. This follows from the range of calculated surface reduction rates which range between .0002μ to .004μ per year depending on the site's location and the obsidian source. Hydration rates for key Papua New Guinea obsidians have been determined from long term experimental laboratory exposure and these are used to evaluate the age of obsidians from selected archaeological sites. By adopting a strategy of measuring hydration in concealed fissures both the weathering rate and the dating of the Papua New Guinea obsidians have been successfully achieved. The dissolution rates of natural obsidians could be useful in considering weathering rates for artificial glasses. An improved system for calculating the annual effective hydration temperature is presented which gives a better control of micro-environmental temperature in its crucial rate determining role. The combined result of these developments gives obsidian hydration dating an enhanced capacity to be a useful and independent dating system

  2. Confronting Dating Violence.

    Science.gov (United States)

    McNulty, Raymond J.; Heller, Daniel A.; Binet, Tracy

    1997-01-01

    To be safe havens for children, schools cannot address the intellect only. Brattleboro (Vermont) Union High School went beyond academics by sponsoring a performance of "The Yellow Dress," a powerful one-woman play about a teenage victim of dating violence. The production challenged participants to unite school and community, intellect…

  3. The Realities of Date Rape.

    Science.gov (United States)

    Presley, Cara; Watson, Jennifer; Williams, Audrey R.

    This poster presentation addresses the issue of date rape, specifically in the college environment. Highlighted are date rape statistics, demographics, and date rape drugs. Also discussed are date rape warnings and prevention strategies. It is concluded that college and university administrators must place the issue of date rape and acquaintance…

  4. Multidecadal climate variability in Brazil's Nordeste during the last 3000 years based on speleothem isotope records

    Science.gov (United States)

    Novello, Valdir F.; Cruz, Francisco W.; Karmann, Ivo; Burns, Stephen J.; Stríkis, Nicolás M.; Vuille, Mathias; Cheng, Hai; Lawrence Edwards, R.; Santos, Roberto V.; Frigo, Everton; Barreto, Eline A. S.

    2012-12-01

    We present the first high resolution, approximately ∼4 years sample spacing, precipitation record from northeastern Brazil (hereafter referred to as ‘Nordeste’) covering the last ∼3000 yrs from 230Th-dated stalagmites oxygen isotope records. Our record shows abrupt fluctuations in rainfall tied to variations in the intensity of the South American summer monsoon (SASM), including the periods corresponding to the Little Ice Age (LIA), the Medieval Climate Anomaly (MCA) and an event around 2800 yr B.P. Unlike other monsoon records in southern tropical South America, dry conditions prevailed during the LIA in the Nordeste. Our record suggests that the region is currently undergoing drought conditions that are unprecedented over the past 3 millennia, rivaled only by the LIA period. Using spectral, wavelet and cross-wavelet analyses we show that changes in SASM activity in the region are mainly associated with variations of the Atlantic Multidecadal Oscillation (AMO) and to a lesser degree caused by fluctuations in tropical Pacific SST. Our record also shows a distinct periodicity around 210 years, which has been linked to solar variability.

  5. Thermoluminescence dating of pottery

    International Nuclear Information System (INIS)

    Higashimura, Takenobu; Ichikawa, Yoneta.

    1978-01-01

    This report is divided into two parts. The first half describes on the history of thermoluminescence dating, and the latter half, the principle and measurement examples. It was in late 1955 that the measurement of radiation dose using thermoluminescence began. The method to thermoluminescence dating was developed when it was found that most natural stones emit the thermoluminescence. About Greek earthen wares, the study of which was presented in 1961 by G. Kennedy of University of California, the dating was able to be made within the standard deviation of 10%. Since then, this dating method progressed rapidly, and a number of laboratories are now forwarding the investigation. In the samples of natural materials, intensity of thermoluminescence I is proportional to natural radiation dose D which has been absorbed by the samples, i.e. I = kD, where k is the susceptibility of thermoluminescence of the samples. Since k is different in each sample, D can be determined by irradiating the sample with β or γ ray of known dose D 0 , measuring its luminescence I 0 , and eliminating k through these two equations, because i 0 = kD 0 . Next, if t is assumed to be the time passed since a pottery was made, D is expressed as Rt, where R is the natural radiation dose per year absorbed by the pottery. Thus t is determined if R is known. The report describes on the method of measuring R. As an example, the results of measurement of the potteries excavated at Iwakura remains, Yorikura, Taishaku-kyo, are listed. Results by 14 C dating are also described for reference. (Wakatsuki, Y.)

  6. Amino acid racemisation dating

    International Nuclear Information System (INIS)

    Murray-Wallace, C.V.

    1999-01-01

    The potential of the time-dependent amino acid racemisation reaction as a method of age assessment was first reported by Hare and Abelson (1968). They noted that in specimens of the bivalve mollusc Mercenaria sp., greater concentrations of amino acids in the D-configuration with increasing fossil age. Hare and Abelson (1968) also reported negligible racemisation in a modern specimen of Mecanaria sp. On this basis they suggested that the extent of amino acid racemisation (epimerisation in the case of isoleucine) may be used to assess the age of materials within and beyond the range of radiocarbon dating. For the past thirty years amino acid racemisation has been extensively applied in Quaternary research as a method of relative and numeric dating, and a particularly large literature has emerged on the subject

  7. Dating fractures in infants

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, K.E., E-mail: kath.halliday@nuh.nhs.uk [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Broderick, N J; Somers, J M [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Hawkes, R [Department of Radiology, Paul O' Gorman Building, Bristol (United Kingdom)

    2011-11-15

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  8. Dating fractures in infants

    International Nuclear Information System (INIS)

    Halliday, K.E.; Broderick, N.J.; Somers, J.M.; Hawkes, R.

    2011-01-01

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  9. Thermoluminescence dating method

    International Nuclear Information System (INIS)

    Zink, A.

    2004-01-01

    A crystal that is submitted to radiation stores energy and releases this energy under the form of light whenever it is heated. These 2 properties: the ability to store energy and the ability to reset the energy stored are the pillars on which time dating methods like thermoluminescence are based. A typical accuracy of the thermoluminescence method is between 5 to 7% but an accuracy of 3% can be reached with a sufficient number of measurement. This article describes the application of thermoluminescence to the dating of a series of old terra-cotta statues. This time measurement is absolute and does not require any calibration, it represents the time elapsed since the last heating of the artifact. (A.C.)

  10. Radiocarbon dating for contributors

    International Nuclear Information System (INIS)

    Jansen, H.S.

    1984-06-01

    This report describes the radiocarbon facility at the Institute of Nuclear Sciences, and is written for potential contributors, current users, and for those who advise others. The report briefly outlines the principles and practices of C-14 dating; with emphasis on factors that enable contributors to judge whether C-14 work is appropriate, and to assist them with the procedures to be followed in order to get the best results. Age determinations, being the main requirements by contributors, have been discussed in detail

  11. Multi-proxy evidence of millennial climate variability from multiple Bahamian speleothems

    Science.gov (United States)

    Arienzo, Monica M.; Swart, Peter K.; Broad, Kenneth; Clement, Amy C.; Pourmand, Ali; Kakuk, Brian

    2017-04-01

    Northern Hemisphere tropical paleoclimate records support significant changes associated with Dansgaard Oeschger (D/O) events and Heinrich stadials 1 to 6 during the last 64,000 years. However, few absolutely dated terrestrial records from the western Atlantic span the last six Heinrich stadials. Here we present geochemical results from three new stalagmites collected from a cave in the Bahamas which encompass Heinrich stadials 1 to 6. We build on a previous study of the δ13C and δ18O values of the calcite and δ18O value of fluid inclusions from a single stalagmite from the same cave spanning the last three Heinrich stadials. Absolute geochronometry using U-Th equilibrium series demonstrates that the stalagmites formed between 63.8 and 13.8 kyr BP. The δ13C and δ18O values of the calcite show higher values associated with Heinrich stadials 1-6, and lower values during the D/O interstadial events. The Sr/Ca ratios of the calcite are shown to be relatively invariant, while in two of the samples the Mg/Ca ratios track the δ13C values. Increases in the δ18O values across Heinrich stadials 1-6 are interpreted as being driven by lower temperatures. The two deeper occurring stalagmites demonstrate increased Mg/Ca ratios and δ13C values during Heinrich stadials 1 and 2 which are interpreted as a signal of reduced flow rates in the epikarst and increased water/rock interactions as a result of increased aridity which potentially occurred across all six Heinrich stadials. The observed reductions in mean annual temperature and amount of precipitation across Heinrich stadials are proposed to be driven by a reduction in sea surface temperatures in the North Atlantic and an expanded Bermuda High. During D/O interstadials, the Bahamas cave records likely indicate warmer and/or wetter climate; however the isotopic shifts are not as significant as the isotopic excursions associated with Heinrich stadials.

  12. Sediment dating in review

    International Nuclear Information System (INIS)

    Prescott, J.R.; Robertson, G.B.

    1997-01-01

    The paper will comment on a few issues of particular relevance to Australasia. Thermoluminescent (TL) methods applied to open sites have been demonstrated to be effective. A particularly good example of this is to be found in the South East of South Australia, where a sequence of low ranges runs roughly parallel with the coast. They represent relict sand dunes left behind, on a slowly rising land surface by successive interglacial incursions of the sea at roughly 120 ka intervals. Comparison with ages established on independent geological grounds allows a test of quartz TL and IRSL ages that is believable back to 500 ka. Older than this, we do not yet understand the physics of the quartz well enough to go unequivocally forward (backward?). Similar results are emerging elsewhere. With dating limits being pushed ever further back, the time variation of the environmental radiation giving rise to the stored luminescent energy needs to be addressed. Particularly at wet sites, radioactive disequilibrium must be considered. In any case, a time profile of the radiation dose rate needs to be determined.In dating a given site or sites the value of ages obtained by any dating method,including C-14, is enhanced by parallel measurements with an different method

  13. The Glacial-Interglacial summer monsoon recorded in southwest Sulawesi speleothems: Evidence for sea level thresholds driving tropical monsoon strength

    Science.gov (United States)

    Kimbrough, A. K.; Gagan, M. K.; Dunbar, G. B.; Krause, C.; Di Nezio, P. N.; Hantoro, W. S.; Cheng, H.; Edwards, R. L.; Shen, C. C.; Sun, H.; Cai, B.; Rifai, H.

    2016-12-01

    Southwest Sulawesi lies within the Indo-Pacific Warm Pool (IPWP), at the center of atmospheric convection for two of the largest circulation cells on the planet, the meridional Hadley Cell and zonal Indo-Pacific Walker Circulation. Due to the geographic coincidence of these circulation cells, southwest Sulawesi serves as a hotspot for changes in tropical Pacific climate variability and Australian-Indonesian summer monsoon (AISM) strength over glacial-interglacial (G-I) timescales. The work presented here spans 386 - 127 ky BP, including glacial terminations IV ( 340 ky BP) and both phases of TIII (TIII 248 ky BP and TIIIa 217 ky BP). This record, along with previous work from southwest Sulawesi spanning the last 40 kyr, reveals coherent climatic features over three complete G-I cycles. The multi-stalagmite Sulawesi speleothem δ18O record demonstrates that on G-I timescales, the strength of the AISM is most sensitive to changes in sea level and its impact on the regional distribution of land and shallow ocean. Stalagmite δ18O and trace element (Mg/Ca) data indicate a rapid increase in rainfall at glacial terminations and wet interglacials. TIV, TIII, TIIIa, and TI are each characterized by an abrupt 3‰ decrease in δ18O that coincides with sea level rise and flooding of the Sunda and Sahul shelves. Strong evidence for a sea level (flooding/exposure) threshold is found throughout the southwest Sulawesi record. This is most clearly demonstrated over the period 230 - 212 ky BP (MIS 7d-7c), when a sea level fall to only -80 to -60 m for 10 kyr results in a weakened AISM and glacial conditions, followed by a full termination. Taken together, both glaciations and glacial terminations imply a sea level threshold driving the AISM between two primary levels of intensity (`interglacial' & `glacial'). These massive, sea-level driven shifts in AISM strength are superimposed on precession-scale variability associated with boreal fall insolation at the equator, indicating

  14. Dating Violence among College Students

    Science.gov (United States)

    Iconis, Rosemary

    2013-01-01

    Dating violence is a significant problem on college campuses. More than one-fifth of the undergraduate dating population are physically abused by their dating partners and an even greater percentage are psychologically abused. Researchers have identified risk factors for college student dating violence. Preventive interventions are strongly…

  15. Flirting in Online Dating

    DEFF Research Database (Denmark)

    Mortensen, Kristine Køhler

    2017-01-01

    Various fields have examined the activity of flirting, predominantly based on experimental and reported data; the interactional workings are therefore often overlooked. Based on emails and chats from two Danish online dating sites, this article investigates how users negotiate romantic connections...... through the flirting strategy of ‘imagined togetherness’, linguistically constructing imagery of a shared future. Using the notion of the chronotope, turn-by-turn analysis demonstrates how users, embedded in the activity of getting to know each other, tenuously communicate romantic interest by alluding...

  16. Bomb pulse radiocarbon dating

    International Nuclear Information System (INIS)

    Tuniz, C.; Zoppi, U.; Hotchkis, M.A.C.

    2004-01-01

    Modern forensic science has to deal not only with homicides and other traditional crimes but also with more global threats such as the smuggling of nuclear materials, clandestine production of weapons of mass destruction, stockpiling of illicit drugs by state controlled groups and war crimes. Forensic applications have always benefited from the use of advanced analytical tools that can characterize materials found at crime scenes. In this paper we will discuss the use of accelerator mass spectrometry (AMS) as an ultrasensitive tool for the crime laboratories of the third millennium. An important objective in forensic science is to order past events chronologically by analysing materials associated with criminal actions. Radiocarbon dating is known to the general public for its application to historical and prehistorical investigations. Examples of forensic significance include the assassination of the Inca Atahualpa by Francisco Pizarro in the early 1530s, the possible murder of the Tyrolean Ice Man (Oetzi) 5300 years ago and the analysis of the burial cloths allegedly associated with the crucifixion of Jesus Christ . Recent murders, including those associated with war crimes in the Balkans during the 1990s, can be studied using 14 C bomb pulse dating. This method has other forensic applications, including investigation of frauds related to food and wine counterfeiting, dating of opium crops and dating of substances used in biological warfare. AMS extends the applicability of the radiocarbon method, allowing the analysis of 14 C in submilligram organic samples. Specific molecular compounds extracted from bones, hair, skin and other carbon bearing substances of forensic significance can now be dated, enhancing the sensitivity and reliability of chronological determinations. AMS can also be used to analyse rare actinide isotopes released into the environment during the clandestine production of nuclear weapons or associated with the smuggling of nuclear materials. In

  17. Updating dating down under

    International Nuclear Information System (INIS)

    Bristow, J.W.

    1986-01-01

    The article deals with the Sensitive High Resolution Ion Microprobe (SHRIMP), Australia's only microprobe and its applications for geochronology. SHRIMP has the ability to analyse tiny areas (less than 30μm across) within crystals directly, the only sample preparation required being polishing of the crystal surface. Most analyses so far have been done on separated crystals prepared as grain mounts, although an increasing number of analyses are now being made of crystals in rock thin sections where their textural associations can be established. Important features of SHRIMP are its double-focusing mass spectrometer and great physical size, more than 8 meters long, employing a magnet weighing six tons. This enables the machine to distinguish ions with atomic masses differing by less than one part in ten thousand while at the same time having a very great sensitivity. SHRIMP was used for dating crustal zircons from southern African Kimberlites. Although low U and Pb abundances presents problems in peak selection and focusing on SHRIMP its was found that kimberlitic zircons could be dated successfully

  18. A 242-year seasonal-resolved speleothem record from Hainan Island: A window into variability of the precipitation δ18O in East Asia

    Science.gov (United States)

    Cai, Y.; An, Z.; Cheng, H.; Edwards, R. L.; Fung, I. Y.; Zhang, H.; Tan, L.; Bi, H.

    2016-12-01

    Hainan Island is located at the gateway of East Asian summer monsoon to the continent. The typical tropical monsoon climate at Hainan island is characterized by wet season during the summer and autumn and dry season during the winter and spring. Here, we present a seasonal resolved speleothem record spanning 242 years ( 50-292 AD) from Xianren Cave (E109°25`, N18°34`), which is situated in the Baoting County, Hainan Province. The monitoring inside the cave shows that the relative humidity kept saturated during the observed periods (one and half years) while the temperature varied seasonally following the temperature changes outside the cave, but with much smaller amplitude. Monthly observation of drip water inside the cave indicates that the isotope composition of drip water mainly responds to the changes in the precipitation isotope composition with less than two months' resident time. The visible annual lamination and distinct fluctuations of calcite Mg, Sr and Ba concentrations corroborate that the high-frequency oscillations of calcite δ18O largely capture the seasonal variation of the isotope composition of precipitation, although the temperature effect cannot be excluded. By setting the heaviest value of annual variation of calcite δ18O as the beginning of each annual cycle, we transferred the δ18O record of 11.2 cm in depth to a δ18O record of 242-year in age. The δ18O record of stalagmite XR-3 demonstrate clearly the annual, decadal and multi-decadal variations of amplitude from 2 to 4‰, in addition to the seasonal oscillation of amplitude varied from 1.5 to 2.5‰. The ensemble empirical mode decomposition results show that the dominant variability (54.6% of the total variance) is captured by the components at the timescale of 3-7 year, while the components on timescales of 22-24 -year, 80-year and 120-year capture 35.0%, 7.0% and 3.4% of the variance, respectively. We contribute the variability of speleothem δ18O at the timescale of 3-7 -year to

  19. Radiocarbon dates XXI

    International Nuclear Information System (INIS)

    Lowdon, J.A.; Blake, W. Jr.

    1981-01-01

    This list includes 105 radiocarbon age determinations on 104 geological samples made by the Radiocarbon Dating Laboratory. They are on samples from various areas as follows: Labrador Shelf (2); Newfoundland (12); Nova Scotia (2); New Brunswick (1); Quebec (3); Ontario (1); Manitoba (1); Alberta (2); British Columbia (15); Yukon Territory (35); Northwest Territories, Mainland (10); Northwest Territories, Arctic Archipelago (21). Details of background and standard for the 2 L and 5 L counters during the period from November 4, 1980 to October 31, 1981 are summarized in Tables 1 and 2; Table 3 gives the number of counts used to determine the average background and standard counting rates; and Table 4 lists the number of different background and standard gas preparations used for counting

  20. U-series isotopes in arc magma

    Energy Technology Data Exchange (ETDEWEB)

    Hawkesworth, C.; Turner, S.; McDermott, F.; Peate, D.; Van Calsteren, P.

    1997-12-31

    Thorium is not readily mobilized in the fluid component along destructive plate margins. Uranium is mobilized, and the resultant fractionation in U/Th can be used to estimate the rates of transfer slab derived components through the mantle wedge. The variations in Th/Yb, and by implication in the fractionation-corrected Th abundances of arc magmas largely depend on the contributions from subducted sediments. It is inferred that the distinctive high Th/Ta ratios of subduction related magmas primarily reflect the Th/Ta ratios of the subducted sediments, and that such high Th/Ta ratios are generated by processes other than those associated with recent subduction-related magmatism. Uranium and thorium isotopes have also been used to evaluate magma residence times within the crust. Thus, separated minerals and groundmass from six rocks erupted in the last 4,000 years from Soufriere on St. Vincent in the Lesser Antilles, scatter about a 50,000 year errorchron on the U-Th equiline diagram (Heath et al., 1977). Models are currently being developed to investigate how such apparent ages may relate to calculated replenishment times in steady state systems. Bulk continental crust has a lower U/Th ratio (0.25) than at least some estimates for the bulk Earth (0.26) and the depleted upper mantle (0.39). However, the island arc rocks with low U/Th ratios appear to have inherited those from subducted sediments, and arc rocks with a low sediment contribution have significantly higher U/Th. Consequently, the U/Th ratios of new crustal material generated along destructive plate margins are significantly higher than those of bulk continental crust. The low average U/Th of bulk crust may be primarily due to different crust generation processes in the Archaean, when U would be less mobile because conditions were less oxidising, and when residual garnet may have had more of a role in crust generation processes. Extended abstract. 4 figs., 23 refs.

  1. Dates fruits classification using SVM

    Science.gov (United States)

    Alzu'bi, Reem; Anushya, A.; Hamed, Ebtisam; Al Sha'ar, Eng. Abdelnour; Vincy, B. S. Angela

    2018-04-01

    In this paper, we used SVM in classifying various types of dates using their images. Dates have interesting different characteristics that can be valuable to distinguish and determine a particular date type. These characteristics include shape, texture, and color. A system that achieves 100% accuracy was built to classify the dates which can be eatable and cannot be eatable. The built system helps the food industry and customer in classifying dates depending on specific quality measures giving best performance with specific type of dates.

  2. Northern Hemisphere Influence on the Position of the SPCZ During MIS3: a High Resolution Glacial Rainfall Record from a Niuean Speleothem

    Science.gov (United States)

    Sinclair, D.; Sherrell, R. M.; Tremaine, D. M.; Sweeney, J. R.; Rowe, H.; Wright, J. D.; Mortlock, R. A.; Hellstrom, J. C.; Cheng, H.; Min, A.; Edwards, R. L.

    2017-12-01

    Here we present a high-resolution glacial paleorainfall record from the heart of the South Pacific Convergence Zone (SPCZ) extracted from a stalagmite from the remote island of Niue (19°03'S 169°52'W). The record spans much of MIS3 (25-45 ka) and captures rapid rainfall changes associated with shifts in the SPCZ. It is clear that rapid climate shifts in the Northern Hemisphere have a strong influence on the SPCZ. All of the warm Dansgaard-Oeschger (`D-O') interstadials across this period are represented by rainfall increases, with D-O Events 9-11 particularly strongly represented. Since Niue lies south of the core of the SPCZ, this implies that rather than shifting northwards (as the ITCZ does), the SPCZ instead rotates clockwise in response to northern Hemisphere warming (analogous to a shift between modern El Nino and La Nina states). We propose that changes to surface ocean temperature gradients in the Eastern Pacific modulate the strength of the Wind Evaporation SST feedback, changing the size and westward penetration of the eastern Pacific dry zone, resulting in changes to the diagonality of the SPCZ. Our record also captures a response to strong northern Hemisphere cooling. The 25-45 ka record is bounded by large hiatuses (inferred dry conditions) coincident with cold Heinrich Stadials (HS) 2 and 5, while HS3 and HS4 are captured as distinct reductions in speleothem growth rate and proxy evidence for declining rainfall. This is consistent with a counter-clockwise rotation of the SPCZ during Northern cooling, supporting our proposed mechanism. Interestingly, our record also captures several other (non-Heinrich) cooling events, including a strong 500-year dry interval at 26ka that is seen in Chinese and Brazilian speleothems and coincides with a strong cooling over Asia (inferred from Greenland dust records). We note the (possibly coincidental) timing between this event and the Oruanui super-eruption at 25.6 ka.

  3. Reconstruction of drip-water δ18O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany

    Directory of Open Access Journals (Sweden)

    T. Kluge

    2013-02-01

    Full Text Available The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany and calculate drip-water δ18Ow values for the Eemian, MIS3, and the Holocene, relying on independent temperature estimates and accounting for disequilibrium. Applying the co-variation method to modern calcite precipitates yields drip-water δ18Ow values in agreement with modern cave drip-water δ18Ow of −7.9 ± 0.3‰, despite large and variable disequilibrium effects in both calcite δ18Oc and Δ47. Reconstructed paleo-drip-water δ18Ow values are lower during colder periods (e.g., MIS3: −8.6 ± 0.4‰ and the early Holocene at 11 ka: −9.7 ± 0.2‰ and show higher values during warmer climatic periods (e.g., the Eemian: −7.6 ± 0.2‰ and the Holocene Climatic Optimum: −7.2 ± 0.3‰. This new approach offers a unique possibility for quantitative climate reconstruction including the assessment of past hydrological conditions while accounting for disequilibrium effects.

  4. Characterization and uranium-series dating of travertine from Suettoe in Hungary

    Energy Technology Data Exchange (ETDEWEB)

    Sierralta, M; Geldern, R van; Frechen, M [Leibniz Institute for Applied Geosciences, Hannover (Germany); Kele, S [Hungarian Academy of Sciences (Hungary); Melcher, F Author [Federal Institute for Geosciences and Natural Resources (Germany)

    2007-07-01

    Full text: Terrestrial carbonate formations, such as travertines, speleothems and lake sediments, are archives of terrestrial climate forcing. At the Suettoe section in Hungary, a succession of travertine is covered by a loess-palaeosol sequence; both are high resolution terrestrial archives of climate and environment change. Uranium-series ({sup 230}Th/U) dating using thermal ionisation mass spectroscopy was carried out to set up a reliable chronological frame for the travertine. As the growth of travertine is complex, pore cements may cause serious problems for precise dating. Therefore, we applied microscopic, mineralogical and geochemical methods to determine the abundance of secondary calcite. The state of alteration of primary spar and micrite was characterized by cathodoluminescence and microprobe analyzes. The travertine from Suettoe showed homogeneous phases of primary calcite, minor micropores and rare pore cements. Stable carbon and oxygen isotope analyzes were carried out to characterize the depositional environment of the Suettoe travertines. The carbon isotopic composition indicated that the source of carbon was a mixture of atmospheric and soil derived CO{sub 2}. Calculated water temperatures based on oxygen isotope data ranged from 22{sup o}C to 31{sup o}C. For uranium-series dating bulk samples were prepared from areas with mainly micrite and spar. {sup 230}Th/U ages were determined applying an isochron approach. As the dense travertine deposits had a dense structure, the bulk sampling method was successfully applied in determining uranium-series ages with much higher precision than former studies with alpha spectrometry could achieve. Travertines from Suettoe yielded Mid-Pleistocene ages ranging from the antepenultimate glacial to the penultimate interglacial (310-240 ka). These results are in agreement with those from OSL and AAR dating of the overlying sediment indicating at least an MIS 7 age for the travertine. (author)

  5. Temporal and geochemical evolution of Miocene volcanism in the Andean back-arc between 36°S and 38°S and U-series analyses of young volcanic centers in the arc and back-arc, Argentina

    DEFF Research Database (Denmark)

    Dyhr, Charlotte Thorup

    New 40Ar/39Ar, major and trace element, and Sr, Nd and Pb isotopic data for the c. 24-7 Ma volcanic rocks from the Andean back-arc (35°S – 38°S) in the Mendoza and Neuquén (Argentina) regions shed light on the Miocene evolution of the back-arc of the Southern Volcanic Zone. Incipient shallowing......-Sr-Pb isotopic compositions. The arc-like component that dominates the geochemistry of the Palaoco rocks is absent in both the Early Miocene and the Pliocene-Pleistocene in the same area. Young volcanic Provinces in the main arc, retro-arc and back-arc are further investigated by U-series analyses which confirm...... the fluid-enriched nature of arc-related rocks (U-excess are found in most rocks) and the more OIB-like nature of the Payún Matrú complex (Th-exsess is observed in all rocks). The fluid addition to the mantle source is modeled revealing timescales of 10 – 100 ka for the fluid enrichment. For the back...

  6. Dating technique tested

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    An analytical technique for dating ground water and polar ice up to a million years old has been successfully tested by scientists at Oak Ridge National Laboratory (ORNL). The system, known as a rare gas atom counter, extends the capabilities of resonance ionization mass spectrometry to include counting single atoms of krypton-81. The counter is composed of a pulsed dye laser operated in tandem with a mass spectrometer to separate the various isotopes of krypton. In a collaborative study, ORNL scientists recently used the method for the first time to count krypton-81 in a liter of ground water removed from a sandstone aquifer near Zurich. Fewer than 1000 krypton-81 atoms were isolated from the ground water samples. According to Bernard Lehman, a collaborating geochemist at the University of Bern, this first test proved that counting the small numbers of krypton-81 atoms necessary to make an estimate of the age of water could actually be done. Among the applications of this method, Lehman says, could be improved siting of locations for the disposal of radioactive wastes

  7. Speleothem (Cave Deposit) Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, and other aspects of climate derived from mineral deposits found in caves. Parameter keywords describe what was measured...

  8. Mass spectrometric 230Th-234U-238U dating of the Devils Hole calcite vein

    International Nuclear Information System (INIS)

    Ludwig, K.R.; Simmons, K.R.; Szabo, B.J.; Riggs, A.C.; Winograd, I.J.; Landwehr, J.M.; Hoffman, R.J.

    1992-01-01

    The Devils Hole calcite vein contains a long-term climatic record, but requires accurate chronologic control for its interpretation. Mass-spectrometric U-series ages for samples from core DH-11 yielding 230 Th ages with precisions ranging from less than 1,000 years (2σ) for samples younger than ∼140 ka (thousands of years ago) to less than 50,000 years for the oldest samples (∼566 ka). The 234 U/ 238 U ages could be determined to a precision of ∼20,000 years for all ages. Calcite accumulated continuously from 566 ka until ∼60 ka at an average rate of 0.7 millimeter per 10 3 years. The precise agreement between replicate analyses and the concordance of the 230 Th/ 238 U and 234 U/ 238 U ages for the oldest samples indicate that the DH-11 samples were closed systems and validate the dating technique in general

  9. Connecting, synchronising, and dating with tephras : principles and applications of tephrochronology in Quaternary research

    International Nuclear Information System (INIS)

    Lowe, D.J.

    2016-01-01

    Tephrochronology is a unique method for linking and dating geological, palaeoecological, palaeoclimatic or archaeological sequences or events. The method relies firstly and fundamentally on stratigraphy and the law of superposition, which apply in any study that connects or correlates deposits from one place to another. Secondly, it relies on characterising and hence identifying or 'fingerprinting' tephra layers using either physical properties evident in the field or those obtained from laboratory analysis, including mineralogical examination by optical microscopy or geochemical analysis of glass shards or crystals (e.g. Fe-Ti oxides, ferromagnesian minerals) using the electron microprobe and other tools. Thirdly, the method is enhanced when a numerical age is obtained for a tephra layer by (1) radiometric methods such as radiocarbon, fission-track, U-series, or Ar/Ar dating, (2) incremental dating methods including dendrochronology or varved sediments or layering in ice cores, or (3) age-equivalent methods such as palaeomagnetism or correlation with marine oxygen isotope stages or palynostratigraphy. Once known, that age can be transferred from one site to the next using stratigraphic methods and by matching compositional characteristics, i.e. comparing 'fingerprints' from each layer. Used this way, tephrochronology is an age-equivalent dating method. (author).

  10. Connecting, synchronising, and dating with tephras : principles and applications of tephrochronology in Quaternary research

    International Nuclear Information System (INIS)

    Lowe, D.J.

    2017-01-01

    Tephrochronology is a unique method for linking and dating geological, palaeoecological, palaeoclimatic or archaeological sequences or events. The method relies firstly and fundamentally on stratigraphy and the law of superposition, which apply in any study that connects or correlates deposits from one place to another. Secondly, it relies on characterising and hence identifying or 'fingerprinting' tephra layers using either physical properties evident in the field or those obtained from laboratory analysis, including mineralogical examination by optical microscopy or geochemical analysis of glass shards or crystals (e.g. Fe-Ti oxides, ferromagnesian minerals) using the electron microprobe and other tools. Thirdly, the method is enhanced when a numerical age is obtained for a tephra layer by (1) radiometric methods such as radiocarbon, fission-track, U-series, or Ar/Ar dating, (2) incremental dating methods including dendrochronology or varved sediments or layering in ice cores, or (3) age-equivalent methods such as palaeomagnetism or correlation with marine oxygen isotope stages or palynostratigraphy. Once known, that age can be transferred from one site to the next using stratigraphic methods and by matching compositional characteristics, i.e. comparing 'fingerprints' from each layer. Used this way, tephrochronology is an age-equivalent dating method. (author).

  11. On the use of δ18Oatm for ice core dating

    Science.gov (United States)

    Extier, Thomas; Landais, Amaelle; Bréant, Camille; Prié, Frédéric; Bazin, Lucie; Dreyfus, Gabrielle; Roche, Didier M.; Leuenberger, Markus

    2018-04-01

    Deep ice core chronologies have been improved over the past years through the addition of new age constraints. However, dating methods are still associated with large uncertainties for ice cores from the East Antarctic plateau where layer counting is not possible. Indeed, an uncertainty up to 6 ka is associated with AICC2012 chronology of EPICA Dome C (EDC) ice core, which mostly arises from uncertainty on the delay between changes recorded in δ18Oatm and in June 21st insolation variations at 65°N used for ice core orbital dating. Consequently, we need to enhance the knowledge of this delay to improve ice core chronologies. We present new high-resolution EDC δ18Oatm record (153-374 ka) and δO2/N2 measurements (163-332 ka) performed on well-stored ice to provide continuous records of δ18Oatm and δO2/N2 between 100 and 800 ka. The comparison of δ18Oatm with the δ18Ocalcite from East Asian speleothems shows that both signals present similar orbital and millennial variabilities, which may represent shifts in the InterTropical Convergence Zone position, themselves associated with Heinrich events. We thus propose to use the δ18Ocalcite as target for δ18Oatm orbital dating. Such a tuning method improves the ice core chronology of the last glacial inception compared to AICC2012 by reconciling NGRIP and mid-latitude climatic records. It is especially marked during Dansgaard-Oeschger 25 where the proposed chronology is 2.2 ka older than AICC2012. This δ18Oatm - δ18Ocalcite alignment method applied between 100 and 640 ka improves the EDC ice core chronology, especially over MIS 11, and leads to lower ice age uncertainties compared to AICC2012.

  12. Impacts of climate change on Middle Eastern societies over the last 2700 years: new results from the Gejkar speleothem, Iraq

    Science.gov (United States)

    Flohr, Pascal; Fleitmann, Dominik; Bosomworth, Matt; Cheng, Hai; Sadekov, Aleksey; Matthews, Roger; Matthews, Wendy; Black, Stuart; Edwards, Lawrence

    2016-04-01

    Climatic and environmental changes are often cited as a major factor for past social, economic, and political changes. This is especially relevant in the semi-arid to arid Middle East, where, however, only few precisely dated, high-resolution climate records are available. Here we present new results from an up to annually resolved stalagmite from Gejkar Cave in the Kurdish Regional Government of Iraq region. Based on Uranium-series dating and annual layer counts, the record dates back ~2700 years, and its annual layer thickness and carbon and oxygen isotope profile appear indicative of precipitation and effective moisture. We also assess if observed decadal to multi-decadal shifts in precipitation are synchronous with socio-economic changes as observed in the archaeological and historical record in the wider Middle East over the last 2000 years, such as the largely prosperous Roman and Byzantine periods, the Seljuq invasion, and the decline of the Ottoman Empire.

  13. Optical stimulated luminescence (OSL) dating

    International Nuclear Information System (INIS)

    Banerjee, D.

    1999-01-01

    Since the pioneering work by Huntley et al. (1985), optical dating is being increasingly recognised as an important technique for establishing a time frame of deposition of sediments (Aitken, 1998). Optical dating differs from thermoluminescence (TL) dating in that visible/infrared light from lasers or LEDs (light-emitting-diodes) is used as a means of stimulation, in contrast to thermal stimulation. It has several advantages over TL dating: (i) the resetting of the OSL (optically stimulated luminescence) clock is more effective than that of TL clock; for sediments transported under water or in other situations where the sediment grains have undergone inhomogeneous bleaching, this property ensures that ages based on optical dating are generally more reliable than TL ages, (ii) the optical dating technique is non-destructive, and multiple readouts of the optical signal is possible; this feature has resulted in the development of single-aliquot and single-grain protocols (Murray and Wintle, 1999; Banerjee et al. 1999), (iii) the sample is not heated as in TL; thus, spurious luminescence is avoided and there is a significant reduction in blackbody radiation. Dating of materials which change phase on heating is also practical, and finally, (iv) thermal quenching of luminescence is negligible, allowing accurate estimation of kinetic parameters using standard techniques and providing access to deep OSL traps. This characteristic may be helpful in extending the limits of optical dating beyond the last 150 ka from a global point of view

  14. Luminescence dating of Netherland's sediments

    NARCIS (Netherlands)

    Wallinga, J.; Davids, F.; Dijkmans, J.W.A.

    2007-01-01

    Over the last decades luminescence dating techniques have been developed that allow earth scientists to determine the time of deposition of sediments. In this contribution we revity: 1) the development of the methodology, 2) tests of the reliability of luminescence dating on Netherlands' sediments;

  15. The isotopic dating of crystals

    International Nuclear Information System (INIS)

    Giuliani, G.; Cheilletz, A.

    1995-01-01

    The first part of this work deals with the answer to the question : why are the crystals dated ? Then, some isotopic dating methods are described : U-Th-Pb, K-Ar, 40 Ar/ 39 Ar, Rb-Sr, Sm-Nd, fission traces, carbon 14 methods. Examples concerning emeralds and diamonds are given. (O.L.). 12 refs., 2 figs

  16. The comparison of absolute dating (Radiocarbon dating) and relative dating of Pringapus and Gondosuli temples

    International Nuclear Information System (INIS)

    Faisal, W; Arumbinang, H; Taftazani, A; Widayati, S; Sumiyatno; Suhardi

    1996-01-01

    The absolute dating (radiocarbon, 14 C dating) and relative dating of Pringapus and Gondosuli temples in Temanggung regency (district) of Central Java Province have been carried out. The field sampling was done especially with the purpose to obtain vertical data, so that excavation method was adopted in the case. The main data were the ecofacts of organic habitation such as bones, woods, charcoals, shells, and paper artefacts. The artefacts data were used as a comparison. The comparative data analysis were conducted at Yogyakarta archaeological Department Laboratory, thus included dating of artefacts which were performed according to archaeological analysis procedures, generally based on the attributes attached to the artefacts, whereas the absolute dating of charcoal samples were performed in the Radiocarbon Dating Laboratory at Yogyakarta Nuclear Research Centre. Based on the relative dating of epigraphy content on the andesit rock from Gondosuli Temple which showed the year of 754 Saka or 832 AD, the Pringapus Temple was estimated to be built in the 850 AD. According to the absolute dating (Radiocarbon Dating with delta 13 C and tree ring corrections) the age for Gondosuli temple based on GDS/LU-2/Spit-7 samples is (384 -602) AD and from GDS/LU-2/Spit-8 = (452 - 652) AD. With these significant differences in the results obtained, it can be concluded that culture environment where the sample were collected already existed before the temple was built. Further investigation is still required

  17. Cavity-based secondary mineralization in volcanic tuffs of Yucca Mountain, Nevada: a new type of the polymineral vadose speleothem, or a hydrothermal deposit?

    Directory of Open Access Journals (Sweden)

    Dublyansky Yuri V.

    2005-07-01

    Full Text Available Secondary minerals (calcite, chalcedony, quartz, opal, fluorite, heulandite, strontianite residing in open cavities in the Miocenerhyolite tuffs of Yucca Mountain, Nevada have been interpreted by some researchers as "speleothemic" formations, deposited as aresult of downward infiltration of meteoric waters (DOE, 2001, Whelan et al., 2002. The major mineral of the paragenesis, calcite,shows spectacular trend of the textural and crystal morphology change: from anhedral granular occurrences, through (optionalplatelet, bladed and scepter varieties, to euhedral blocky morphologies. The trend is consistent with the overall decrease in thesupesaturation of the mineral forming solution. Stable isotope properties of calcite evolve from 13C-enriched (δ13C = +4 to +9 ‰ PDBat early stages of growth to 13C-depleted (-5 to -10 ‰ at late stages. The non-cyclic character of the isotope record and extremevariations of isotopic values argue against the meteoric origin of mineral forming fluids. The δ13C >4 ‰ PDB require isotope partitioningbetween dissolved CO2 and CH4, which is only possible in reducing anoxic environment, but not in aerated vadose zone.Fluid inclusions studied in calcite, quartz and fluorite revealed that the minerals were deposited from thermal solutions. Thetemperatures were higher at early stages of mineral growth (60 to 85oC and declined with time. Most late-stage calcites containonly all-liquid inclusions, suggesting temperatures less than ca. 35-50oC. Minerals collected close to the major fault show the highesttemperatures. Gases trapped in fluid inclusions are dominated by CO2 and CH4; Raman spectrometry results suggest the presenceof aromatic/cyclic hydrocarbon gases. The gas chemistry, thus, also indicates reduced (anoxic character of the mineral formingfluids.Secondary minerals at Yucca Mountain have likely formed during the short-term invasion(s of the deep-seated aqueous fluidsinto the vadose zone. Following the invasion

  18. 36Chlorine exposure dating of a terminal moraine in the Galicica Mountains, Macedonia

    Science.gov (United States)

    Gromig, R.; Mechernich, S.; Ribolini, A.; Dunai, T. J.; Wagner, B.

    2015-12-01

    The glaciation history of the Balkan Peninsula is subject of research since the late 19th century. To date, only a few moraines on the Balkan Peninsula are dated, mainly using 10Be exposure dating applied on quartz bearing rocks. Since large parts of the Balkan Peninsula mountains are composed of carbonatic rocks, absolute age dating is restricted to 36Cl exposure dating, which, to date, was not conducted in this region yet. So far, an absolute chronological control in limestone-dominated areas is limited to U-series minimum ages of calcitic cements. In order to obtain more information about the timing of the glaciation history on the Balkan Peninsula, we investigated a terminal moraine in a NNE-facing cirque in the Galicica Mountains (40°56´N, 20°49´E) in the Former Yugoslav Republic of Macedonia. The cirque comprises a series of nested moraine ridges at the base of the cirque wall, with the largest one being sampled. Samples from five limestone boulders in crest position (≈ 2050 m a.s.l.) were taken and pre-treated for AMS measurement at the University of Cologne. Three preliminary ages point to a moraine formation in the course of a late Pleistocene glaciation, either Last Glacial Maximum or Younger Dryas. The data were discussed concerning corrections for topographic shielding, snow cover, inheritance, and erosion. However, five AMS re-measurements are currently in progress in order to refine the correlation of the moraine formation to a specific glacial period. The resulting ages will be compared to sediments of the adjacent Lakes Ohrid and Prespa, which represent valuable climatic and environmental archives. Several studies on these sediments were carried out in order to reconstruct relative changes in temperature and moisture availability. Moreover, the inferred moraine formation ages will be compared to glaciation reconstructions of other mountainous regions on the Balkan Peninsula to improve the knowledge on past climatic conditions.

  19. AHP 47: A NIGHT DATE

    Directory of Open Access Journals (Sweden)

    Phun tshogs dbang rgyal ཕུན་ཚོགས་དབང་རྒྱལ།

    2017-04-01

    Full Text Available The author was born in 1993 in Ska chung (Gaqun Village, Nyin mtha' (Ningmute Township, Rma lho (Henan Mongolian Autonomous County, Rma lho (Huangnan Tibetan Autonomous Prefecture, Mtsho sngon (Qinghai Province, PR China. Night dating was popular for teenage boys some years ago. They rode horses and yaks when they went night dating. They generally rode yaks, because horses were important for their families and used for such important tasks as pursuing bandits and going to the county town for grain and supplies. An early experience with night dating is described.

  20. Dating the humans by radiocarbon

    International Nuclear Information System (INIS)

    Fedi, M.E.

    2011-01-01

    Radiocarbon has become a very powerful tool used for dating. This paper deals with a specific application of 1 4C i.e. dating of humans. Attention is focused on those aspects that, if neglected, might lead to a misinterpretation of the results or to an unsatisfying accuracy of the measurement. After a brief description of the main principles on which the radiocarbon method is based and of Accelerator Mass Spectrometry, examples taken from the research activity of INFN-LABEC (Laboratorio di Tecniche Nucleari per I Beni Culturali) in Florence are presented. The case of the relic of St. Francis represents an example of dating not directly human remains but other objects that can be associated to them. The case of two burials from the archaeological area of Baratti-Populonia, in Tuscany, gives the possibility to show the importance of estimating the human palaeodiet when dating bone samples.

  1. Dating by electron paramagnetic resonance

    International Nuclear Information System (INIS)

    Poupeau, G.; Rossi, A.M.

    1984-01-01

    Some natural materials behave like dosimeters in front of the ionizing particle flux coming from environmental radioactivity and the cosmic radiation. This property is used for the dating by Electron Paramagnetic Resonance (EPR). Before presenting the basic principles of the EPR analysis and the dating method which uses such a phenomenous, it is reviewed several types of application currently in course of development. (L.C.) [pt

  2. Radiocarbon dating of lake sediments

    OpenAIRE

    Pocevičius, Matas

    2016-01-01

    Matas Pocevičius, Radiocarbon dating of lake sediments, bachelor thesis, Vilnius University, Faculty of Physics, Department of General Physics and Spectroscopy, physics, Vilnius, 45 p., 2016. The aim of this study is to evaluate the possibility of radiocarbon dating application for Tapeliai lake bottom sediments. The literature review discusses topics related to accelerator mass spectrometry, principles of radiocarbon formation, importance of nuclear fallout for 14C, possible applications of ...

  3. Radiocarbon dating of iron artefacts

    Energy Technology Data Exchange (ETDEWEB)

    Cresswell, R. [Australian National Univ., Canberra, ACT (Australia). Dept. of Nuclear Physics

    1997-12-31

    Iron artefacts are generally dated by association or on stylistic grounds. This may not give a true indication of the date of manufacture, or may not be possible if the piece is out of context, ambiguous in style, or a copy. Obtaining a direct date on the artefact would be preferable. During the processes of manufacture, carbon is incorporated into the iron from the fuel source. If the fuel is of a material containing contemporaneous carbon, i.e. has an ambient radiocarbon signature, e.g. charcoal, then we may reliably radiocarbon date the artefact by extracting this carbon. Care must be taken, however, to ensure that re-working has not introduced multiple sources of carbon that would give an erroneous date. Detailed chemical analysis must precede radiocarbon analysis. Sample size is determined by carbon content, and before the advent of accelerator mass spectrometry, several tens of grams of carbon were required for radiocarbon dating (van der Merwe, 1969), prohibiting this method except for high-carbon cast-irons and bulk samples, e.g. caches of nails. AMS permits the analysis of sub-gram pieces of iron (Cresswell, 1991), thereby permitting the analysis of museum pieces with only minimal loss of material, and small fragments of iron recovered from archaeological sites. A few examples are given to illustrate these points. Paper no. 41; Extended abstract. 6 refs.

  4. Radiocarbon dating of iron artefacts

    International Nuclear Information System (INIS)

    Cresswell, R.

    1997-01-01

    Iron artefacts are generally dated by association or on stylistic grounds. This may not give a true indication of the date of manufacture, or may not be possible if the piece is out of context, ambiguous in style, or a copy. Obtaining a direct date on the artefact would be preferable. During the processes of manufacture, carbon is incorporated into the iron from the fuel source. If the fuel is of a material containing contemporaneous carbon, i.e. has an ambient radiocarbon signature, e.g. charcoal, then we may reliably radiocarbon date the artefact by extracting this carbon. Care must be taken, however, to ensure that re-working has not introduced multiple sources of carbon that would give an erroneous date. Detailed chemical analysis must precede radiocarbon analysis. Sample size is determined by carbon content, and before the advent of accelerator mass spectrometry, several tens of grams of carbon were required for radiocarbon dating (van der Merwe, 1969), prohibiting this method except for high-carbon cast-irons and bulk samples, e.g. caches of nails. AMS permits the analysis of sub-gram pieces of iron (Cresswell, 1991), thereby permitting the analysis of museum pieces with only minimal loss of material, and small fragments of iron recovered from archaeological sites. A few examples are given to illustrate these points

  5. Microscale radiocarbon dating of paintings

    International Nuclear Information System (INIS)

    Hendriks, Laura; Hajdas, Irka; McIntyre, Cameron; Kueffner, Markus; Ferreira, Ester S.B.; Scherrer, Nadim C.

    2016-01-01

    In this paper, radiocarbon dating of paintings using minimal sample sizes has been investigated, in an effort to address the problem of limited access to sample material in paintings. 14 C analyses were conducted on signed and dated paintings from two Swiss artists of the twentieth century. The selected paintings dated from the 1930s and 1960s, provided the opportunity to evaluate the dating accuracy on paintings realized before and after 1950 AD when the 14 C bomb peak was created, as a result of the nuclear tests conducted in the 1950/1960s. The work focused on the one hand on minimizing the size of the canvas sample required for accelerator mass spectrometer radiocarbon measurement on the gas ion source of the MICADAS and, on the other hand, on testing the possibility of dating the organic binder of the paint. Following careful characterization of the paint composition by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy, paints containing no other carbon source than the natural organic binder were identified and dated. (orig.)

  6. Microscale radiocarbon dating of paintings

    Energy Technology Data Exchange (ETDEWEB)

    Hendriks, Laura; Hajdas, Irka; McIntyre, Cameron [ETH Zurich, Ion Beam Physics, Zurich (Switzerland); Kueffner, Markus; Ferreira, Ester S.B. [SIK-ISEA, Zurich, Zurich (Switzerland); Scherrer, Nadim C. [Bern University of Applied Sciences, HKB, Bern (Switzerland)

    2016-03-15

    In this paper, radiocarbon dating of paintings using minimal sample sizes has been investigated, in an effort to address the problem of limited access to sample material in paintings. {sup 14}C analyses were conducted on signed and dated paintings from two Swiss artists of the twentieth century. The selected paintings dated from the 1930s and 1960s, provided the opportunity to evaluate the dating accuracy on paintings realized before and after 1950 AD when the {sup 14}C bomb peak was created, as a result of the nuclear tests conducted in the 1950/1960s. The work focused on the one hand on minimizing the size of the canvas sample required for accelerator mass spectrometer radiocarbon measurement on the gas ion source of the MICADAS and, on the other hand, on testing the possibility of dating the organic binder of the paint. Following careful characterization of the paint composition by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy, paints containing no other carbon source than the natural organic binder were identified and dated. (orig.)

  7. Linguistic Dating of Biblical Texts

    DEFF Research Database (Denmark)

    Ehrensvärd, Martin Gustaf

    2003-01-01

    For two centuries, scholars have pointed to consistent differences in the Hebrew of certain biblical texts and interpreted these differences as reflecting the date of composition of the texts. Until the 1980s, this was quite uncontroversial as the linguistic findings largely confirmed the chronol......For two centuries, scholars have pointed to consistent differences in the Hebrew of certain biblical texts and interpreted these differences as reflecting the date of composition of the texts. Until the 1980s, this was quite uncontroversial as the linguistic findings largely confirmed...... the chronology of the texts established by other means: the Hebrew of Genesis-2 Kings was judged to be early and that of Esther, Daniel, Ezra, Nehemiah, and Chronicles to be late. In the current debate where revisionists have questioned the traditional dating, linguistic arguments in the dating of texts have...... come more into focus. The study critically examines some linguistic arguments adduced to support the traditional position, and reviewing the arguments it points to weaknesses in the linguistic dating of EBH texts to pre-exilic times. When viewing the linguistic evidence in isolation it will be clear...

  8. Kimberley rock art dating project

    International Nuclear Information System (INIS)

    Walsh, G.L.; Morwood, M.

    1997-01-01

    The art's additional value, unequalled by traditionally recognised artefacts, is its permanent pictorial documentation presenting a 'window' into the otherwise intangible elements of perceptions, vision and mind of pre-historic cultures. Unfortunately it's potential in establishing Kimberley archaeological 'big picture' still remains largely unrecognised. Some of findings of the Kimberley Rock Art Dating Project, using AMS and optical stimulated luminescence (OSL) dating techniques, are outlined. It is estimated that these findings will encourage involvement by a greater diversity of specialist disciplines to tie findings into levels of this art sequence as a primary reference point. The sequence represents a sound basis for selecting specific defined images for targeting detailed studies by a range of dating technique. This effectively removes the undesirable ad hoc sampling of 'apparently old paintings'; a process which must unavoidably remain the case with researchers working on most global bodies of rock art

  9. ESR dating of fault rocks

    International Nuclear Information System (INIS)

    Lee, Hee Kwon

    2002-03-01

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then trow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs grain size shows a plateau for grains below critical size : these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected from the Yangsan fault system. ESR dates from the this fault system range from 870 to 240 ka. Results of this research suggest that long-term cyclic fault activity continued into the pleistocene

  10. ESR dating of fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2002-03-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then trow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs grain size shows a plateau for grains below critical size : these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected from the Yangsan fault system. ESR dates from the this fault system range from 870 to 240 ka. Results of this research suggest that long-term cyclic fault activity continued into the pleistocene.

  11. 32Si dating of sediments

    International Nuclear Information System (INIS)

    Morgenstern, U.

    2004-01-01

    Brief explanation of the use of 32 Si in the dating of sediments. 32 Si , with a half-life of c.140 years, can be applied in the age range 30-1000 years. An appropriate dating tool for that time range is essential because it includes three very important epochs: the impact of human colonisation and industrialisation during the last 150 years, the Little Ice Age between about 1650 AD and 1850 AD, and the last part of the Medieval Climatic Optimum. 23 refs

  12. The complexity behind the date

    CERN Multimedia

    2009-01-01

    For the waiting world, and indeed for most of us here at CERN, ‘the LHC schedule’ simply means the date that the LHC will restart - and we only take notice when that end-date changes. But in fact the schedule is a constantly evolving intricate document coordinating all the repairs, consolidation and commissioning in every part of the machine. So, what actually goes on behind the scenes in timing and planning all the work on one of the most complex scientific instruments ever built?

  13. The use of damaged speleothems and in situ fault displacement monitoring to characterise active tectonic structures: an ex¬ample from Západní Cave, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Briestenský, Miloš; Stemberk, Josef; Rowberry, Matthew David

    2014-01-01

    Roč. 43, č. 1 (2014), s. 129-138 ISSN 0583-6050 R&D Projects: GA MŠk OC 625.10; GA ČR GA205/05/2770; GA ČR GA205/06/1828; GA ČR GA205/09/2024; GA MŠk LM2010008 Institutional support: RVO:67985891 Keywords : active tectonics * speleothem damage * fault displacement * stress field * Lusatian Thrust Zone Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.451, year: 2014

  14. Isotopic Characteristics and Age Dating of the Pumice in Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    陈丽蓉; 翟世奎; 申顺喜

    1994-01-01

    The data on the isotope compositions of rubidium,strontium and oxygen in the pumice ofOkinawa Trough are reported for the first time.The ages of the pumice were successfully dated with themethod of U-series disequilibrium.Then,the material source,crystallization evolution of magma and activi-ty cycles of volcanos are explored.Isotopic data show that pumice magma was originally from the mantle,but had undergone a full crystal-lization differentiation and had been contaminated to a fair extent by crust-derived materials before the mag-ma was erupted out of the sea floor.According to the dating results available so far,the earliest volcaniceruption in Okinawa Trough occurred about 70,000 a ago and the latest eruption was about 10,000 a B.P.During this period,there were three volcanic eruption cycles which were respectively corresponding to themiddle Late Pleistocene,the late Late Pleistocene and the Early Holocene.

  15. Recent advances in thermoluminescence dating

    International Nuclear Information System (INIS)

    Aitken, M.J.

    1984-01-01

    Initially the application of thermoluminescent dating was to ancient pottery and other baked clay, the detection of forgeries in art ceramics having a particularly powerful impact. In recent years there has been a growing extension of TL into non-pottery materials. Heated flints from paleolithic fire-places is one application. Another is in the dating of igneous rocks from recent volcanic events; formerly this had been impossible on account of the malign phenomenon of non-thermal ('anomalous') fading exhibited by volcanic minerals but this is now being circumvented by utilising TL in the 600 0 C region of the glow curve. TL dating has also been extended to unburnt calcite, one application being stalagmitic floors in paleolithic caves. Another recent development is the use of TL for dating aeolian sediment and some types of waterborne sediment. These developments give prospect of establishing a TL-based chronology, both for archaeology and quaternary research, extending back well beyond the range of radiocarbon, perhaps reaching a million years ago. (author)

  16. Sexual Intimacy in Dating Relationships

    Science.gov (United States)

    Peplau, Letitia Anne; And Others

    1977-01-01

    The patterning of sexual interaction in male-female dyads and the links between sexual behavior and emotional intimacy were investigated as part of a two-year study of college dating couples. Traditional sexual role playing was found to be common. (Author/AM)

  17. Online Dating and Conjugal Bereavement

    Science.gov (United States)

    Young, Dannagal Goldthwaite; Caplan, Scott E.

    2010-01-01

    This study examined self-presentation in the online dating profiles of 241 widowed and 280 divorced individuals between 18 and 40 years old. A content analysis of open-ended user-generated profiles assessed the presence or absence of various themes, including the user's marital status, the backstory of their lost relationship, and whether they…

  18. (including travel dates) Proposed itinerary

    Indian Academy of Sciences (India)

    Ashok

    31 July to 22 August 2012 (including travel dates). Proposed itinerary: Arrival in Bangalore on 1 August. 1-5 August: Bangalore, Karnataka. Suggested institutions: Indian Institute of Science, Bangalore. St Johns Medical College & Hospital, Bangalore. Jawaharlal Nehru Centre, Bangalore. 6-8 August: Chennai, TN.

  19. Comparative study of radioimmunoassay dates

    International Nuclear Information System (INIS)

    Venegas Sanchez, Ruth.

    1986-01-01

    The radioimmunoassay is frequently used in clinical chemistry for the concentration determination of several substances like hormones as thyrotropine and thyroxine. In this experiment the dates of tyroxine radioimmunoassay are processed by three methods: a) like the recommendation of the IAEA, b) Dr. G. Chase method, c) according to the provider. The best method was Dr. Chase's. (author)

  20. Peer Group Influences on Adolescent Dating Aggression

    Science.gov (United States)

    Connolly, Jennifer; Friedlander, Laura

    2009-01-01

    The peer group is a critical social context for dating and romantic relationships. Peer groups provide opportunities to meet potential dating partners and set norms for acceptable dating behaviors. This article explores how peer groups influence dating and dating aggression, as well as how they can be used in prevention efforts. It also reviews…

  1. 31 CFR 596.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY TERRORISM LIST GOVERNMENTS SANCTIONS REGULATIONS General Definitions § 596.302 Effective date. The term effective date refers to the effective date of the...

  2. Linguistic dating of biblical texts

    DEFF Research Database (Denmark)

    Young, Ian; Rezetko, Robert; Ehrensvärd, Martin Gustaf

    Since the beginning of critical scholarship biblical texts have been dated using linguistic evidence. In recent years this has become a controversial topic, especially with the publication of Ian Young (ed.), Biblical Hebrew: Studies in Chronology and Typology (2003). However, until now there has...... been no introduction and comprehensive study of the field. Volume 1 introduces the field of linguistic dating of biblical texts, particularly to intermediate and advanced students of biblical Hebrew who have a reasonable background in the language, having completed at least an introductory course...... in this volume are: What is it that makes Archaic Biblical Hebrew archaic , Early Biblical Hebrew early , and Late Biblical Hebrew late ? Does linguistic typology, i.e. different linguistic characteristics, convert easily and neatly into linguistic chronology, i.e. different historical origins? A large amount...

  3. Fission tracks dating for obsidian

    International Nuclear Information System (INIS)

    Picon, C.

    1991-01-01

    Obsidian from South America are dated by fission tracks methods. Samples are irradiated in a nuclear reactor with a flux of 10 15 n/cm 2 . Results, corrected by 'Plateau' methods, are the following: obsidian from Bolivia: 4.14 x 10 6 yr., Ecuador: 8.79 x 10 5 yr., Colombia: 3.52 x 10 6 yr., Peru: 6.55 x 10 6 yr., Chile: 1.13 x 10 6 yr. (MMZ). 5 refs., 3 tabs

  4. Radiokrypton dating coming of age

    Institute of Scientific and Technical Information of China (English)

    Zheng-Tian Lu

    2016-01-01

    The dream of radiokrypton dating began in 1969 when Heinz Hugo Loosli and Hans Oeschger of the University of Bern first detected the decay of81Rr(half-life=230 000 yr)in krypton gas extracted from air[1].This isotope is produced in the upper atmosphere by cosmic-ray-induced spallation and neutron-activation of stable krypton.Due to its long residence time(105 yr)in the atmosphere,81Rr is uniformly

  5. Current topics in ESR dating

    International Nuclear Information System (INIS)

    Skinner, Anne R.

    2011-01-01

    After over 25 years, the use of electron spin resonance (ESR) is well-established in dating sites of geological, paleontological and archaeological interest. Like any scientific technique, there have been changes in understanding and in methodology. Improvements have not, however, changed the observation that external dose calculations are still a significant source of uncertainty in ages. Examples from Europe, Africa and the Americans illustrate this point. For Pradayrol Cave (France), the occupation age, 330 ka, is unchallenged, making this the oldest known Neanderthal site in France. For Roc de Marsal, also in France, on the other hand, discrepancies between TL and sedimentary dose rates imply substantial differences in interpretation. In the Western Egyptian Desert, where artifacts and datable material are not well-correlated, the dating results show consistency with expectations based on global climate change, even in deflated sites. Climate change is also the question in geological studies in the Bahamas where, despite concerns about cosmic dose history, ESR dates confirm other evidence for sea level changes. We show that an uncertain age is not the same as an impossible one.

  6. ESR dating of fault rocks

    International Nuclear Information System (INIS)

    Lee, Hee Kwon

    2003-02-01

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then grow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs. grain size shows a plateau for grains below critical size; these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected near the Gori nuclear reactor. Most of the ESR signals of fault rocks collected from the basement are saturated. This indicates that the last movement of the faults had occurred before the Quaternary period. However, ESR dates from the Oyong fault zone range from 370 to 310 ka. Results of this research suggest that long-term cyclic fault activity of the Oyong fault zone continued into the Pleistocene

  7. ESR dating of fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2003-02-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then grow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs. grain size shows a plateau for grains below critical size; these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected near the Gori nuclear reactor. Most of the ESR signals of fault rocks collected from the basement are saturated. This indicates that the last movement of the faults had occurred before the Quaternary period. However, ESR dates from the Oyong fault zone range from 370 to 310 ka. Results of this research suggest that long-term cyclic fault activity of the Oyong fault zone continued into the Pleistocene.

  8. School Counselors' Role in Dating Violence Intervention

    Science.gov (United States)

    Craigen, Laurie M.; Sikes, April; Healey, Amanda; Hays, Danica

    2009-01-01

    Dating violence among adolescents is a major public health concern. The purpose of this paper is to examine five factors of which school counselors must be aware in order to recognize, intervene, and report incidence of dating violence. These factors are (a) understanding the diverse definitions of dating violence, (b) recognizing dating violence…

  9. Thermoluminescence dating of pleistocene sediments

    International Nuclear Information System (INIS)

    Poupeau, G.; Souza, J.H.; Rivera, A.

    1984-01-01

    After a short introduction on recent trends in quaternary geochronology, this article focuses on the thermoluminescence dating of sediments, whose principles and present limits and prospects are discussed. Results are presented for the TL behaviour of sands from various geological contexts in Brazil. They show that the coarse (approx. 100-200μm) quartz fraction of coastal and intra continental, eolian and fluvial-type deposits, might be datable by TL from the upper Holocene to at least the basis of the upper Pleistocene, with a precision of + - 10-15%. (Author) [pt

  10. Thermoluminescence dating of pleistocene sediments

    International Nuclear Information System (INIS)

    Poupeau, G.; Souza, J.H.

    1984-01-01

    After a short introduction on recent trends in quaternary geochronology, this article focuses on the thermoluminescence (TL) dating of sediments, whose principles, present limits and prospects are discussed. Results are presented for TL behavior of sands from various geological contexts in Brazil. They show that the coarse (approx. 100-200 μm) quartz fraction of coastal and intracontinental, eolian and fluvial - type deposits, might be datable by TL from the upper Holocene to at least the base of the upper Pleistocene, with a precision of +- 10-15%. (Author) [pt

  11. Uranium-series dating of fossil bones from alpine caves

    International Nuclear Information System (INIS)

    Leitner-Wild, E.; Steffan, I.

    1993-01-01

    During the course of an investigation of fossil cave bear populations the uranium-series method for absolute age determination has been applied to bone material. The applicability of the method to bone samples from alpine caves is demonstrated by the concordance of U/Th and U/Pa ages and cross-checks with the radiocarbon method. Stratigraphic agreement between bone ages and carbonate speleothem ages also indicates the potential of the uranium-series method as a suitable tool for the age determination of fossil bones from alpine cave environments. (Author)

  12. Substitution of Sugar with Dates Powder and Dates Syrup in Cookies Making

    OpenAIRE

    W.A. Alsenaien; R.A. Alamer; Zhen-Xing Tang; S.A. Albahrani; M.A. Al-Ghannam; S.M. Aleid

    2015-01-01

    In this study, the effects of dates powder and dates syrup as a sugar substitution, on the physical properties and sensory attributes of cookies were studied. An increase in firmness and moisture content of cookies supplemented with dates was obtained. The diameter and spread ratio of cookies showed a decrease with increasing levels of date powder or date syrup. Partial replacement of sugar with date powder or date syrup produced cookies with more dark and red color. Sensory evaluation result...

  13. 85Kr dating of groundwater

    International Nuclear Information System (INIS)

    Rozanski, K.; Florkowski, T.

    1978-01-01

    The possibility of 85 Kr dating of groundwater is being investigated. The method of gas extraction from 200 to 300 litres of water sample has been developed. The Argon and Krypton mixture, separated from the gas extracted from water, was counted in a 1.5 ml volume proportional counter. The amount of krypton gas in the counter was determined by mass spectrometry. A number of surface and groundwater samples were analyzed indicating an 85 Kr concentration ranging from present atmospheric content (river water) to zero values. 85 Kr 'blank value' was determined to be about 5 per cent of present 85 Kr atmospheric content. For groundwater samples, the mean residence time in the system was calculated assuming the exponential model and known 85 Kr input function. Further improvement of the method should bring higher yield of krypton separation and lower volume of water necessary for analysis. (orig.) [de

  14. Blind-date Conversation Joining

    Directory of Open Access Journals (Sweden)

    Luca Cesari

    2013-07-01

    Full Text Available We focus on a form of joining conversations among multiple parties in service-oriented applications where a client may asynchronously join an existing conversation without need to know in advance any information about it. More specifically, we show how the correlation mechanism provided by orchestration languages enables a form of conversation joining that is completely transparent to clients and that we call 'blind-date joining'. We provide an implementation of this strategy by using the standard orchestration language WS-BPEL. We then present its formal semantics by resorting to COWS, a process calculus specifically designed for modelling service-oriented applications. We illustrate our approach by means of a simple, but realistic, case study from the online games domain.

  15. Making a date with radiocarbon

    International Nuclear Information System (INIS)

    Gribbin, J.

    1979-01-01

    The use of 14 C dating techniques for samples of organic materials up to 50,000 years old is discussed with especial reference to adjustment necessary to take account of both the most recent figure for the 14 C half-life and also the natural fluctuations in the production of 14 C over 50,000 years. Methods of detection and the accuracy of the measurements are considered. It is hoped that future developments including both the possibility of counting 14 C ions directly using an accelerator as a mass spectrometer, and also the use of laser enrichment techniques will not only push back the radiocarbon calendar to 100,000 years but will also allow the use of much smaller samples than before. (U.K.)

  16. A 500-year seasonally resolved δ18O and δ13C, layer thickness and calcite aspect record from a speleothem deposited in the Han-sur-Lesse cave, Belgium

    Science.gov (United States)

    Van Rampelbergh, M.; Verheyden, S.; Allan, M.; Quinif, Y.; Cheng, H.; Edwards, L. R.; Keppens, E.; Claeys, P.

    2015-06-01

    Speleothem δ18O and δ13C signals enable climate reconstructions at high resolution. However, scarce decadal and seasonally resolved speleothem records are often difficult to interpret in terms of climate due to the multitude of factors that affect the proxy signals. In this paper, a fast-growing (up to 2 mm yr-1) seasonally laminated speleothem from the Han-sur-Lesse cave (Belgium) is analyzed for its δ18O and δ13C values, layer thickness and changes in calcite aspect. The studied record covers the period between AD 2001 and 1479 as indicated by layer counting and confirmed by 20 U / Th ages. The Proserpine proxies are seasonally biased and document drier (and colder) winters on multidecadal scales. Higher δ13C signals reflect increased prior calcite precipitation (PCP) and lower soil activity during drier (and colder) winters. Thinner layers and darker calcite relate to slower growth and exist during drier (and colder) winter periods. Exceptionally dry (and cold) winter periods occur from 1565 to 1610, at 1730, from 1770 to 1800, from 1810 to 1860, and from 1880 to 1895 and correspond to exceptionally cold periods in historical and instrumental records as well as European winter temperature reconstructions. More relative climate variations, during which the four measured proxies vary independently and display lower amplitude variations, occur between 1479 and 1565, between 1610 and 1730, and between 1730 and 1770. The winters during the first and last periods are interpreted as relatively wetter (and warmer) and correspond to warmer periods in historical data and in winter temperature reconstructions in Europe. The winters in the period between 1610 and 1730 are interpreted as relatively drier (and cooler) and correspond to generally colder conditions in Europe. Interpretation of the seasonal variations in δ18O and δ13C signals differs from that on a decadal and multidecadal scale. Seasonal δ18O variations reflect cave air temperature variations and

  17. Make a date with a tree

    International Nuclear Information System (INIS)

    Baillie, M.; Pilcher, J.

    1988-01-01

    The paper concerns the use of dendrochronology to check the accuracy of radiocarbon dating. The Belfast chronology is described - this involves wood samples precisely dated by tree ring analysis and analysed by high-precision radiocarbon analysis. The analysis resulted in the first continuous high-precision calibration of the radiocarbon time-scale, and confirmed the relationship between radiocarbon dates and tree-ring dates. The use of radiocarbon dating to reveal the age of wood samples that have too few rings to produce an accurate date, is also outlined. (U.K.)

  18. The scientific dating of standing buildings.

    Science.gov (United States)

    Alcock, Nathaniel W

    2017-11-17

    The techniques of dendrochronology (tree-ring dating) and radiocarbon (14C) dating are described, as they are applied to historic buildings. Both rely on determining the felling dates of the trees used in their construction. For dendrochronology, the construction of master chronologies and the matching of individual ring-width sequences to them is described and, for radiocarbon dating, the use of tree-ring results in calibration. Results of dating are discussed, ranging from the cathedrals of Peterborough and Beauvais and the development of crown-post roof structures, to the dating and identification of standing medieval peasant houses, particularly those built using cruck construction.

  19. 17 CFR 248.128 - Effective date, compliance date, and prospective application.

    Science.gov (United States)

    2010-04-01

    ... Affiliate Marketing § 248.128 Effective date, compliance date, and prospective application. (a) Effective date. This subpart is effective September 10, 2009. (b) Mandatory compliance date. Compliance with this... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Effective date, compliance...

  20. Radiocarbon dates for Rangitoto and Motutapu, a consideration of dating accuracy

    International Nuclear Information System (INIS)

    Law, R.G.

    1975-01-01

    The carbon dates for the eruptions of Rangitoto and the occupation of Maori sites on Motutapu contain inconsistencies which are explicable only after the dates have been corrected to allow for the nature of the dating method. The only date which is reasonably established is a 14th or 15th century dating for the ash shower covering Motutapu. (auth.)

  1. Geophysical Insights from Archaeomagnetic Dating

    Science.gov (United States)

    Holme, R.; Lodge, A.; Suttie, N.; Shaw, J.; Hill, M. J.; Linford, P.

    2009-12-01

    We report on work which has been undertaken towards developing an improved methodology for archaeomagnetic dating of archaeological samples through the use of a dedicated field model. In this talk, we focus on the more general (non-archaeological) implications of our results. Our work has focused on Europe, taking advantage of the better spatial and temporal coverage of available samples. Nevertheless, we model the field globally, using an a priori model (such as, for example, CALS7K) to constrain the field away from the regions of available data. This is advantageous over the use of a local field modelling methodology, as it allows us to examine the physical consequences of structure in our model (for example, in terms of the spectra of the field and secular variation at the core-mantle boundary), and to control possible edge effects in the model, which in a local model might produce an unphysical solution. By focusing on one particular region, we produce models that may not be optimal in terms of global structure, but allow us to investigate the data content in the region where it may provide the most information on core-field evolution. In parallel, we have been expanding the archaeointensity record for Great Britain, towards producing an archaeointensity curve for the UK which could ultimately be used for dating of unoriented samples (such as pot sherds). This new record, combined with other recently acquired high-quality intensity data, allows us to consider the evolution of global geomagnetic field strength in parallel with a good model of directional measurements; from 1590, the GUFM model is appropriate. Recent attempts to determine global intensity variation have used all available data (some of uncertain quality) to quantify variations in field strength. By instead focusing on a more limited dataset of known quality, we are able to examine intensity trends in greater detail. We present evidence that the intensity of the field was higher prior to 1840 than

  2. U-series radioactive disequilibria 238U-230Th-226Ra: discussions on sources and processes responsible for volcanism of the Andean cordillera and on the deglaciation in Iceland

    International Nuclear Information System (INIS)

    Chmeleff, J.

    2005-10-01

    Thanks to precise analyses of uranium series radioactive disequilibria, permitted by improvements of mass spectrometry data acquisition and optimization of chemistry, two questions were tackled and answers about the periods of glaciation in Iceland and the petrogenesis of Andean lavas were proposed. Two methods were used to date lava flows from the Reykjanes peninsula and the island of Heimaey, in Iceland, directly linked to the periods of deglaciation or reheating around the last ice age. An original method based on the use of segregation veins present in the lava flows has been developed. Thanks to the formation of this particular geological object this methods permits to be freed from xeno-crystals when using the internal isochron method in the 238 U- 230 Th system. Using this method some constraints are brought both on the quaternary geology of the area of Reykjavik and on the age of the end of the Wurm glaciation on Heirnaey. In parallel, due to the homogeneity of the historical and Holocene lavas of the Reykjanes peninsula, regarding the ( 230 Th/ 232 Th) and Th/U ratios, it is possible to derive the ( 230 Th/ 232 Th) ratio in time to determine the age of lava flows installed during the ice age. Thus we confirmed that the magnetic excursion recorded in the Skalamaelifell lava flow is most probably the same one as that of Laschamp-Olby and that at this time (approximately 48.000 years) the Reykjanes peninsula was entirely covered with a glacier. Thanks to this method the extent of the glacier was also constrained by dating of a picritic shield around 22.000 years, thus the peninsula has to be free of any ice cap despite the fact that glaciation is the most intense around this time.Then Andean arc magmas petrogenesis was constrained in time and space. Almost systematic excesses of 226 Ra compared to 230 Th in lavas of austral, southern and northern volcanic zones of the Andes (AVZ, SVZ and NVZ) constrain the ascending time from the source to the surface after

  3. A 500 year seasonally resolved δ18O and δ13C, layer thickness and calcite fabric record from a speleothem deposited in equilibrium of the Han-sur-Lesse cave, Belgium

    Science.gov (United States)

    Van Rampelbergh, M.; Verheyden, S.; Allan, M.; Quinif, Y.; Cheng, H.; Edwards, L.; Keppens, E.; Claeys, P.

    2014-10-01

    Speleothem δ18O and δ13C signals have already proven to enable climate reconstructions at high resolution. However, seasonally resolved speleothem records are still scarce and often difficult to interpret in terms of climate due to the multitude of factors that can affect the proxy signals. In this paper, a fast growing (up to 2 mm yr-1) seasonally laminated speleothem from the Han-sur-Lesse cave (Belgium) is analyzed for its δ18O and δ13C values, layer thickness and changes in calcite fabric. The studied part of the speleothem covers the most recent 500 years as indicated by layer counting and confirmed by 20 U/Th-ages. Epikarst recharge occurs mainly in winter and lesser during spring and fall. a good correlation can be established between lower winter temperatures and lower winter precipitation (DJF) based on the measured data by the Belgian meteorological institute since 1833 indicating that a dry winter is also a cold winter. Colder and dryer winters cause lower winter recharge and generally drier conditions in the cave. Lower winter recharge decreases the amount of isotopically light (δ18O) winter precipitation added to the epikarst in comparison to the heavier spring and fall waters, which leads to a net increase in δ18O value of the water in the epikarst. Increased δ18O values in the Proserpine are consequently interpreted to reflect colder and dryer winters. Higher δ13C signals are interpreted to reflect increased prior calcite precipitation (PCP) due to colder and dryer winters, when recharge is lower. Thinner layers and darker calcite relate to slower growth and occur when drip rates are low and when the drip water calcium ion concentration is low due to increased PCP, both caused by lower recharge during periods with colder and dryer winters. Exceptionally cold and dry winters cause the drip discharge to decrease under a certain threshold value inducing anomalies in the measured proxy records. Such anomalies occur from 1565 to 1610, from 1770 to

  4. Dates and Times Made Easy with lubridate

    Directory of Open Access Journals (Sweden)

    Garrett Grolemund

    2011-04-01

    Full Text Available This paper presents the lubridate package for R, which facilitates working with dates and times. Date-times create various technical problems for the data analyst. The paper highlights these problems and oers practical advice on how to solve them using lubridate. The paper also introduces a conceptual framework for arithmetic with date-times in R.

  5. Attempt at ESR dating of tooth enamel of French middle pleistocene sites

    International Nuclear Information System (INIS)

    Bahain, J.J.; Sarcia, M.N.; Falgueres, C.; Yokoyama, Y.

    1993-01-01

    Tooth enamel samples from four important French middle Pleistocene sites are analyzed by the ESR method. ESR ages were calculated using uranium uptake mathematical models and compared with U-series results. (author)

  6. Reservoir effects in radiocarbon dating

    International Nuclear Information System (INIS)

    Head, M.J.

    1997-01-01

    Full text: The radiocarbon dating technique depends essentially on the assumption that atmospheric carbon dioxide containing the cosmogenic radioisotope 14 C enters into a state of equilibrium with all living material (plants and animals) as part of the terrestrial carbon cycle. Terrestrial reservoir effects occur when the atmospheric 14 C signal is diluted by local effects where systems depleted in 14 C mix with systems that are in equilibrium with the atmosphere. Naturally, this can occur with plant material growing close to an active volcano adding very old CO 2 to the atmosphere (the original 14 C has completely decayed). It can also occur in highly industrialised areas where fossil fuel derived CO 2 dilutes the atmospheric signal. A terrestrial reservoir effect can occur in the case of fresh water shells living in rivers or lakes where there is an input of ground water from springs or a raising of the water table. Soluble bicarbonate derived from the dissolution of very old limestone produces a 14 C dilution effect. Land snail shells and stream carbonate depositions (tufas and travertines) can be affected by a similar mechanism. Alternatively, in specific cases, these reservoir effects may not occur. This means that general interpretations assuming quantitative values for these terrestrial effects are not possible. Each microenvironment associated with samples being analysed needs to be evaluated independently. Similarly, the marine environment produces reservoir effects. With respect to marine shells and corals, the water depth at which carbonate growth occurs can significantly affect quantitative 14 C dilution, especially in areas where very old water is uplifted, mixing with top layers of water that undergo significant exchange with atmospheric CO 2 . Hence, generalisations with respect to the marine reservoir effect also pose problems. These can be exacerbated by the mixing of sea water with either terrestrial water in estuaries, or ground water where

  7. Dating fractures and fracture movement in the Lac du Bonnet Batholith

    International Nuclear Information System (INIS)

    Gascoyne, M.; Brown, A.; Ejeckam, R.B.; Everitt, R.A.

    1997-04-01

    This report examines and summarizes all work that has been done from 1980 to the present in determining the age of rock crystallization, fracture initiation, fracture reactivation and rates of fracture movement in the Lac du Bonnet Batholith to provide information for Atomic Energy of Canada Limited's (AECL) Canadian Nuclear Fuel Waste Management Program. Geological and petrographical indicators of relative age (e.g. cross-cutting relationships, sequences of fracture infilling minerals, P-T characteristics of primary and secondary minerals) are calibrated with radiometric age determinations on minerals and whole rock samples, using 87 Rb- 87 Sr, 40 K- 39 Ar, 40 Ar- 39 Ar and fission track methods. Most fractures and fracture zones inclined at low angles are found to be ancient features, first formed in the Early Proterozoic under conditions of deuteric alteration. Following some movement on fractures in the Late Proterozoic and Early Paleozoic, reactivation of fractures during the Pleistocene is established from uranium-series dating methods and use of stable isotopic contents of fracture infilling minerals (mainly calcite). Some indication of movement on fracture zones during the Pleistocene is given by electron spin resonance dating techniques on fault gouge. The slow rate of propagation of fractures is indicated by mineral infillings, their P-T characteristics and U-series calcite ages in a fracture in sparsely fractured rock, accessible from AECL's Underground Research Laboratory. These results collectively indicate that deep fractures observed in the batholith are ancient features and the fracturing and jointing in the upper 200 m is relatively recent (< 1 Ma) and largely a result of stress release. (author)

  8. Radiocarbon dating of soils, a review

    International Nuclear Information System (INIS)

    Scharpenseel, H.W.; Schiffmann, H.

    1977-01-01

    The application of radiocarbon dating techniques for pedological purposes is reviewed in chronological sequence of its phases of introduction. Initially dating of charcoal and buried paleosols was dominating and accompanied by few soil dating attempts of recent soil formations on the basis of extracted humic acid-C. The following controversy regarding the potentialities and limitations of recent soil dating, still being involved in the intact turnover processes of modern biodynamics, led to intensive search for the relatively oldest, most favorable C-fraction, particularly a biologically inert C-fraction of the organic C-pool. Inclusion of C-14 dating in pedogenetic working concepts required soil profile date-scanning in order to reveal the age versus depth interdependence. (orig./HK) [de

  9. Sample processing procedures and radiocarbon dating

    International Nuclear Information System (INIS)

    Svetlik, Ivo; Tomaskova, Lenka; Dreslerova, Dagmar

    2010-01-01

    The article outlines radiocarbon dating routines and highlights the potential and limitations of this method. The author's institutions have been jointly running a conventional radiocarbon dating laboratory using the international CRL code. A procedure based on the synthesis of benzene is used. Small samples are sent abroad for dating because no AMS instrumentation is available in the Czech Republic so far. Our laboratory plans to introduce routines for the processing of milligram samples and preparation of graphitized targets for AMS

  10. Thermoluminescence dating of Indian archaeological sites

    International Nuclear Information System (INIS)

    Singhvi, A.K.; Sharma, Y.P.; Agrawal, D.P.

    1983-01-01

    In an attempt to provide a chronology for Indian archaeological sites, an extensive pottery dating programme was initiated during 1978-1979. So far we have provided a chronology for seven important Indian archaeological sites. The dated cultures include: 1) the Ochre Colour Ware culture, 2) the Pre-Harappan culture, 3) the megalithic culture and 4) the Painted Grey Ware culture. A complete survey of recently measured TL dates are presented in a model format similar to that used in Radiocarbon. (author)

  11. How AMS dating changed my life

    International Nuclear Information System (INIS)

    Spriggs, M.

    2001-01-01

    Accelerator mass spectrometry (AMS) radiocarbon dating was developed in the late 1970s. Remembering back to a time before AMS dating was available to archaeologists is a bit like trying to remember how we ever survived without desktop computers, email or automatic teller machines. My own particular interest in AMS dating was an inevitable offshoot from my long-established interest in chronometric hygiene, or 'getting the dates right'. In this paper I attempt to illustrate that accurate dating matters, by discussing some examples of AMS dating projects with which I have been involved over the last six years or so. In relation to these projects, AMS has given us the ability to date sites which we could not before. It has enabled us to provide more detailed stratigraphies when datable materials are rare. It has allowed us to date materials we could not date before, such as rock art pigments. It has been able to provide indications of the degree of site disturbance in the absence of other obvious forms of evidence. And it has allowed us to assess claims for the antiquity of particular material cultural types and faunal introductions. (author). 41 refs

  12. AMS Radiocarbon Dating at Notre Dame

    Science.gov (United States)

    Howard, Sean

    2014-09-01

    Current development of a local radiocarbon dating method using Accelerator Mass Spectrometry (AMS) at the University of Notre Dame seeks to provide sensitive, reproducible, and accurate measurements for future interdisciplinary projects. While AMS has been the premier radiocarbon dating method for a few decades, repurposing Notre Dame's FN Tandem accelerator for radiocarbon dating has provided many unique challenges. Experiments have shown radiocarbon dating possible and reproducible using the FN Tandem accelerator, found optimal settings for said accelerator, and established sensitivity limits comparable to dedicated radiocarbon dating facilities. In addition, there is ongoing work to create a local chemistry lab to convert organic artifacts into graphite samples to be dated locally. Once the chemistry side has been completed, several artifacts from the IAEA's radiocarbon intercomparison have been procured. Dating these previously studied artifacts will provide an additional measure on the accuracy and repeatability of both the accelerator and chemical treatment. Provided that these IAEA artifacts are dated successfully, exciting projects will ensue, such as the authentication of artwork and dating of anthropological samples.

  13. NERC radiocarbon dating: 1975-1985

    International Nuclear Information System (INIS)

    Bowen, D.Q.; Harkness, D.D.

    1986-06-01

    The paper reviews the work of the Natural Environment Research Council Radiocarbon Dating Laboratory in connection with Quaternary research, over the last decade. A description is given of the development of the dating service and in-house research. Quaternary research investigations aided by radiocarbon dating are described under the topic headings: The late Devensian glacial maximum, late glacial, middle Devensian, palaeomagnetic secular variation in lake sediments, vegetational history, faunal history, palaeolimnology, ground water, volcanology, periglacial research, palaoeohydrology, geomorphology, quaternary events in low-latitudes, environmental archaeology, archaeology, deep sea sediments, continental shelf, coastal geomorphology, and radiocarbon dating in Antarctica. (U.K.)

  14. NALPS: a precisely dated European climate record 120–60 ka

    Directory of Open Access Journals (Sweden)

    R. Boch

    2011-11-01

    Full Text Available Accurate and precise chronologies are essential in understanding the rapid and recurrent climate variations of the Last Glacial – known as Dansgaard-Oeschger (D-O events – found in the Greenland ice cores and other climate archives. The existing chronological uncertainties during the Last Glacial, however, are still large. Radiometric age data and stable isotopic signals from speleothems are promising to improve the absolute chronology. We present a record of several precisely dated stalagmites from caves located at the northern rim of the Alps (NALPS, a region that favours comparison with the climate in Greenland. The record covers most of the interval from 120 to 60 ka at an average temporal resolution of 2 to 22 yr and 2σ-age uncertainties of ca. 200 to 500 yr. The rapid and large oxygen isotope shifts of 1 to 4.5‰ occurred within decades to centuries and strongly mimic the Greenland D-O pattern. Compared to the updated Greenland ice-core timescale (GICC05modelext the NALPS record confirms the timing of rapid warming and cooling transitions between 118 and 106 ka, but suggests younger ages for D-O events between 106 and 60 ka. As an exception, the timing of the rapid transitions into and out of the stadial following GI 22 is earlier in NALPS than in the Greenland ice-core timescale. In addition, there is a discrepancy in the duration of this stadial between the ice-core and the stalagmite chronology (ca. 2900 vs. 3650 yr. The short-lived D-O events 18 and 18.1 are not recorded in NALPS, provoking questions with regard to the nature and the regional expression of these events. NALPS resolves recurrent short-lived climate changes within the cold Greenland stadial and warm interstadial successions, i.e. abrupt warming events preceding GI 21 and 23 (precursor-type events and at the end of GI 21 and 25 (rebound-type events, as well as intermittent cooling events during GI 22 and 24. Such superimposed events have not yet been documented

  15. Using microwaves in Disinsection of dates

    International Nuclear Information System (INIS)

    Zouba, Anis

    2008-01-01

    The date palm plays a very significant role in Tunisia in term of culture as well as social, economic and ecological aspects. The production of the dates which is estimated to 120.000 tons/year ensures the principal income for the majority of the oasis population of the South of Tunisia and constitutes the basis for agricultural, industrial, commercial and tourist activities, offering million of working days. The date palm is cultivated mainly for the production of dates which are consumed locally or also exported abroad but for its by-products (food of the cattle, wind breaks, fuel, construction) which are marketed and/ or used in the everyday life thus taking part in the sedentarisation of the populations and the maintenance of a fragile socio-economic balance. The date moth, Ectomyelois ceratoniae Zell. ( L will epidoptera, Pyralidae) is without question the most significant problem of the Tunisian date palm. The infestation of dates in the field and in the storage and packing houses enormously depreciates the marketable quality of dates and risk to compromise exports in particular those of the variety Deglet Nour. rates of infestations of about 20% are often recorded in Tunisia where as the European standards require rates lower than 5%. In Tunisia the desinsectisation of dates is done until now by the use of methyl bromide, its high toxicity substantially reduces the duration of date treatment, and consequently the treated volumes. The replacement of this product becomes an urgent need its use will not be authorized by 2015. Within the framework of a agreement between the Regional Research Center in Oasis Agriculture (CRRAO), The Interprofessional Grouping of Fruits (GIF), and the Italian Company IMETEC, the use one of micro-waves as a desinsectisation method of dates was evaluated. The results of this present work showed that total desinsectisation of dates by microwaves can be obtained only with homogeneous dates in term of water content. Total

  16. Chromatographic separation of fructose from date syrup.

    Science.gov (United States)

    Al Eid, Salah M

    2006-01-01

    The objective of this study is to provide a process for separating fructose from a mixture of sugars containing essentially fructose and glucose, obtained from date palm fruits. The extraction procedure of date syrup from fresh dates gave a yield of 86.5% solids after vacuum drying. A process for separating fructose from an aqueous solution of date syrup involved adding the date syrup solutions (20, 30 and 40% by weight) to a chromatographic column filled with Dowex polystyrene strong cation exchange gel matrix resin Ca2 + and divinylbenzene, a functional group, sulfonic acid, particle size 320 microm, with a flow rate of 0.025 and 0.05 bed volume/min, under 30 and 70 degrees C column temperature. After the date sugar solution batch, a calculated quantity of water was added to the column. Glucose was retained by the resin more weakly than fructose and proceeded faster into the water batch flowing ahead. Three fractions were collected: a glucose-rich fraction, a return fraction, and a fructose-rich fraction. The return fraction is based on when the peaks of fructose and glucose were reached, which could be determined by means of an analyzer (polarimeter) based on the property of glucose and fructose solutions to turn the polarization level of polarized light. A high yield of fructose is obtained at 70 degrees C column temperature with a flow rate of 0.025 bed volume/min and date syrup solution containing 40% sugar concentration. The low recovery by weight obtained using date syrup solutions having a sugar concentration of 20 and 30%, encourages the use of a concentration of 40%. However, with the 40% date syrup supply the average concentrations of glucose and fructose in the return fractions were more than 40%, which can be used for diluting the thick date syrup solution extracted from dates.

  17. 75 FR 57252 - Designated Transfer Date

    Science.gov (United States)

    2010-09-20

    ..., as the date for the transfer of functions to the Bureau of Consumer Financial Protection (``CFPB... other laws. After consulting with the heads of the agencies whose functions will transfer to the CFPB... July 21, 2011, as the transfer date will advance the mission of the CFPB and promote an orderly and...

  18. 12 CFR 563g.6 - Effective date.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Effective date. 563g.6 Section 563g.6 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY SECURITIES OFFERINGS § 563g.6 Effective date. (a) Except as provided for in paragraph (d) of this section, an offering circular filed by a...

  19. 40 CFR 425.05 - Compliance dates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Compliance dates. 425.05 Section 425.05 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE CATEGORY General Provisions § 425.05 Compliance dates...

  20. Jealousy during Dating among Female College Students

    Science.gov (United States)

    Khanchandani, Laveena; Durham, Thomas W.

    2009-01-01

    This study examined the relationship between several situational and personality variables and jealousy in dating relationships among 100 college women volunteers who completed a series of questionnaires about themselves and their dating situations. Six research questions were examined. Results showed that jealousy was lower for women in a steady…

  1. 21 CFR 211.137 - Expiration dating.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Expiration dating. 211.137 Section 211.137 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DRUGS... § 211.137 Expiration dating. (a) To assure that a drug product meets applicable standards of identity...

  2. 16 CFR 314.5 - Effective date.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Effective date. 314.5 Section 314.5 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF CONGRESS STANDARDS FOR SAFEGUARDING CUSTOMER INFORMATION § 314.5 Effective date. (a) Each financial institution subject to the...

  3. 7 CFR 1421.101 - Maturity dates.

    Science.gov (United States)

    2010-01-01

    ... filed and disbursed except, for transferred marketing assistance loan collateral. The maturity date for transferred marketing assistance loan collateral will be the maturity date applicable to the original loan... AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS GRAINS AND SIMILARLY HANDLED COMMODITIES-MARKETING...

  4. Dating violence and suicidal behavior in adolescents.

    Science.gov (United States)

    Holmes, Kristin; Sher, Leo

    2013-01-01

    The aim of this paper is to assess the possible consequences of adolescent physical, emotional and sexual dating violence through a review of the literature on the topic. An electronic search of major biomedical bibliographic databases (Pubmed, ISI, PsycINFO) was used to retrieve articles providing information on the prevalence rates, risk factors, associated consequences and possible preventive measures for adolescent dating violence across different populations. Currently, there have been few longitudinal studies conducted to identify potential risk factors for entering a violent dating relationship in adolescence. Risky behaviors such as early sexual intercourse may predispose someone for victimization. Dating violence itself is also a predictor of future dating violence. Adolescent dating violence was associated with an increase in other violence-related behaviors, substance use, depression, poorer educational outcomes, posttraumatic stress, unhealthy weight control and risky sexual behavior. The association between adolescent dating violence and an increase in suicidal behavior is a major public health concern. Future research should focus on longitudinal studies so that a causal relationship between dating violence and suicidality may be better understood.

  5. Peer Involvement in Adolescent Dating Violence

    Science.gov (United States)

    Stephenson, Pam S.; Martsolf, Donna; Draucker, Claire Burke

    2013-01-01

    This study investigated the ways in which peers are involved in adolescent dating violence. Eighty-eight young adults aged 18-21 were interviewed and asked to reflect on aggressive dating relationships they experienced as teens. The researchers used grounded theory to analyze the data. Findings showed that male and female peers were involved in…

  6. Teen Dating Violence Prevention Program Assessment

    Science.gov (United States)

    Lucas, Quincy Arrianna Rose

    2013-01-01

    The American Psychological Association (APA) has identified the prevention of and intervention in relationship violence as a top priority (APA, n.d.). According to the Center for Disease Control and Prevention's 2012 Teen Dating Violence Fact Sheet, dating violence is a serious problem in the United States. In accordance with Foshee et al. (1998):…

  7. 46 CFR 308.552 - Effective date.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Effective date. 308.552 Section 308.552 Shipping... Cargo Insurance Iv-General § 308.552 Effective date. This subpart shall be effective as and when the... commerce of the United States cannot be obtained on reasonable terms and conditions from companies...

  8. 38 CFR 3.54 - Marriage dates.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Marriage dates. 3.54..., Compensation, and Dependency and Indemnity Compensation Relationship § 3.54 Marriage dates. A surviving spouse may qualify for pension, compensation, or dependency and indemnity compensation if the marriage to the...

  9. Ambiguity and violence in adolescent dating relationships.

    Science.gov (United States)

    Draucker, Claire Burke; Martsolf, Donna; Stephenson, Pam Shockey

    2012-08-01

    Little is known about dyadic processes that lead to adolescent dating violence. The purpose of this study was to examine the phenomenon of relationship ambiguity in adolescent dating relationships to better understand how ambiguity contributes to violence and aggression between dating partners. Data were drawn from 88 narratives of young adults who had participated in a study on adolescent dating violence. Interpretive phenomenology was used to produce an in-depth description of the phenomenon of relationship ambiguity. Relationship ambiguity results in differing expectations between partners regarding closeness and intimacy, fidelity, and obligation. These differences lead to conflicts that set the stage for violence and aggression in adolescent dating relationships. A series of recommendations for clinicians working with adolescents are presented. © 2012 Wiley Periodicals, Inc.

  10. Record date in Serbian company law

    Directory of Open Access Journals (Sweden)

    Arsić Zoran

    2011-01-01

    Full Text Available The right of the shareholder to participate in and vote at the general meeting is determined based on the shares he holds on a certain date prior to the general meeting (record date. However, the rules regulating the record date deviate from the principle of indivisibility of shares. In extreme cases it is possible to have persons, none of which are shareholders at a given time, to participate in and vote at the general meeting. Hence, it is possible to have persons with no investment interest in the company to decide, for example, on adoption of financial reports, or on disposal of high-value assets. This issue, by its virtue, is not put forward in cases where there was no transfer of shares in the period between the record date and the date of the general meeting.

  11. Monitoring of a fast-growing speleothem site from the Han-sur-Lesse cave, Belgium, indicates equilibrium deposition of the seasonal δ18O and δ13C signals in the calcite

    Science.gov (United States)

    Van Rampelbergh, M.; Verheyden, S.; Allan, M.; Quinif, Y.; Keppens, E.; Claeys, P.

    2014-10-01

    Speleothems provide paleoclimate information on multimillennial to decadal scales in the Holocene. However, seasonal or even monthly resolved records remain scarce. Such records require fast-growing stalagmites and a good understanding of the proxy system on very short timescales. The Proserpine stalagmite from the Han-sur-Less cave (Belgium) displays well-defined/clearly visible darker and lighter seasonal layers of 0.5 to 2 mm thickness per single layer, which allows a measuring resolution at a monthly scale. Through a regular cave monitoring, we acquired a good understanding of how δ18O and δ13C signals in modern calcite reflect climate variations on the seasonal scale. From December to June, outside temperatures are cold, inducing low cave air and water temperature, and bio-productivity in the soil is limited, leading to lower pCO2 and higher δ13C values of the CO2 in the cave air. From June to December, the measured factors display an opposite behavior. The absence of epikarst water recharge between May and October increases prior calcite precipitation (PCP) in the vadose zone, causing drip water to display increasing pH and δ13C values over the summer months. Water recharge of the epikarst in winter diminishes the effect of PCP and as a result the pH and δ13C of the drip water gradually decrease. The δ18O and δ13C signals of fresh calcite precipitated on glass slabs also vary seasonally and are both reflecting equilibrium conditions. Lowest δ18O values occur during the summer, when the δ13C values are high. The δ18O values of the calcite display seasonal variations due to changes in the cave air and water temperature. The δ13C values reflect the seasonal variation of the δ13CDIC of the drip water, which is affected by the intensity of PCP. This same anticorrelation of the δ18O versus the δ13C signals is seen in the monthly resolved speleothem record that covers the period between 1976 and 1985 AD. Dark layers display lower δ18O and higher δ13C

  12. Linking the distribution of carbon isotope ratios in soil carbonates and speleothems to climate conditions in the past: A model for the dependence of respiration rate on soil moisture

    Science.gov (United States)

    Liu, Y.; Ibarra, D. E.; Winnick, M.; Caves Rugenstein, J. K.; Oster, J. L.; Druhan, J. L.

    2017-12-01

    The carbon isotope compositions (δ13C) of atmospheric CO2, C3-origin organic carbon, and limestone epikarst differ substantially, resulting in variable δ13C signatures recorded in secondary soil carbonates and speleothems which represent a mixture of these sources. Even though this signal has been widely used in paleoclimate studies, the extent to which carbonate δ13C is influenced by the dynamic response of organic carbon respiration rates to soil moisture variations has yet to be fully evaluated [1]. Soils that are rewetted after a prolonged drought commonly display a peak in respiration rate followed by relaxation to a lower steady state in both lab incubation experiments and field observations. This transient behavior, known as the Birch effect, has been extensively observed across a broad range of locations and soil types, and may generate more than 50% of the total respired CO2 in some ecosystems [2]. Here, we seek to identify the influence of the Birch effect on carbonate δ13C records based on a moisture-dependent modeling approach. We report compiled respiration rates of soils from the literature and fit these data as a function of soil moisture, before imposing exponential dampening with depth and applying the resulting function in a production-diffusion equation [3]. We then implement a mass balance calculation for the δ13C value of carbonate precipitated from a mixture of atmospheric and respired CO2, including mass-dependent fractionation associated with diffusive transport. Our results offer a novel prediction for depth-resolved carbonate δ13C as a function of soil moisture, and suggest that Birch effect signals may be recorded in soil carbonates and influence the magnitude of carbonate δ13C variations in speleothems. Thus, we illustrate a prediction for the range of carbonate δ13C recorded in terrestrial carbonates and suggest that differences in the range of carbonate δ13C may indicate changes in soil moisture variability, providing a new

  13. Time-scales of erosion and weathering processes in the Himalayan river system: Element and isotope approach using the U-series; Constantes de temps des processus d'erosion et d'alteration dans le systeme himalayen: approche geochimique elementaire et isotopique par les series de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Granet, M

    2007-06-15

    The time-scales of erosion and weathering processes are key parameters which need to be determined to understand the response of the reliefs to external forcing like tectonics, climate and human activities. They were recovered by using U-series nuclides analyzed in sediments and suspended materials carried by the Himalayan rivers of the Ganges and Brahmaputra basins. In the Ganges basin, the time-scales of weathering determined from the study of coarse sediments carried by the Kali Gandaki range from several ky, where the uplift is located, to 350 ky. Such values indicate that the bed-rocks are in situ weathered for a long period before the weathering residual products get transported in the rivers as coarse sediments. At the outlet of the high range, these sediments are carried by the tributaries of the Ganges, the Gandak and Ghaghara, during a transfer period of about 100 ka. The study of the sediments at the outlet of the Brahmaputra tributaries allows to propose time-scales of weathering ranging from 110 to 270 ky. Such long periods confirm that during their transfer in the plains, the sediments are temporarily trapped at several places in the basins. In the Ganges and Brahmaputra rivers, the time-scales of sedimentary transfer are 575 and 160 ky, respectively. These values, which are of the same order as their response times, are much longer than the timescales of the Quaternary climate oscillations. It confirms the buffering action of the asiatic alluvial plains for the high-frequency sediment flux variations in response to external forcing in the chain. The study of suspended materials suggests that their chemical compositions result from the mixing of coarse river sediments with fine particles from various locations in the basin which are affected by vegetation recycling. By contrast to coarse sediments, the time-scales of transfer for the suspended materials are fast, e.g. a few ky, pointing the potential of U-series nuclides to assess particle transport

  14. 12 CFR 41.28 - Effective date, compliance date, and prospective application.

    Science.gov (United States)

    2010-01-01

    ... TREASURY FAIR CREDIT REPORTING Affiliate Marketing § 41.28 Effective date, compliance date, and prospective... an affiliate to make solicitations to a consumer if the bank receives such information prior to...

  15. 16 CFR 680.28 - Effective date, compliance date, and prospective application.

    Science.gov (United States)

    2010-01-01

    ... REPORTING ACT AFFILIATE MARKETING § 680.28 Effective date, compliance date, and prospective application. (a... part shall not prohibit you from using eligibility information that you receive from an affiliate to...

  16. 12 CFR 571.28 - Effective date, compliance date, and prospective application.

    Science.gov (United States)

    2010-01-01

    ... THE TREASURY FAIR CREDIT REPORTING Affiliate Marketing § 571.28 Effective date, compliance date, and... receive from an affiliate to make solicitations to a consumer if you receive such information prior to...

  17. Longitudinal relationships between individual and class norms supporting dating violence and perpetration of dating violence.

    Science.gov (United States)

    Taylor, Katherine A; Sullivan, Terri N; Farrell, Albert D

    2015-03-01

    Dating violence is commonly perpetrated in adolescence, making it imperative to understand risk factors in order to inform prevention efforts. Although individual norms supporting dating violence are strongly related to its perpetration, few studies have examined their longitudinal impact. Moreover, the influence of class norms (i.e., norms for students in the same grade, cohort, and school) supporting dating violence on perpetration has rarely been studied. The current study examined longitudinal relationships between individual and class norms supporting dating violence and perpetration of physical and psychological dating violence. Participants were two cohorts of sixth graders from 37 schools who were in dating relationships at Wave 1 and 6 months later at Wave 2 (N = 2,022; 43% female; 52% African American, 21% Latino/a, 20% White, and 7% other). The analyses used a multilevel approach, with students represented at Level 1 and classes (n = 74) at Level 2. The models tested direct effects of Wave 1 individual and class norms supporting dating violence on subsequent changes in perpetration of dating violence at Wave 2 and the extent to which gender moderated these relationships. The findings indicated that greater individual norms supporting male dating violence predicted greater change in perpetration of physical and psychological dating violence and greater individual norms supporting female dating violence predicted greater change in perpetration of psychological dating violence. Greater class norms supporting male dating violence predicted greater change in perpetration of physical dating violence; whereas greater class norms supporting female dating violence predicted less change in perpetration of physical dating violence. These findings highlight the need to address norms in early adolescence.

  18. Dating of fossil hominid: problems and perspectives

    International Nuclear Information System (INIS)

    Poupeau, G.; Danon, J.; Baksi, A.K.

    1984-01-01

    The hominid dating anterior to the Homo Erectus has been based up to now on the rocks and minerals geochronology of vulcanic origem in stratigraphic relation with the fossils. Two methods are widely used, potassium-argon and uranium fission track dating. The vulcanic material dating; lava, lephra, associated with the hominid leavings show big difficults essentially connected to several types of contamination and modification. Two available examples inside the east-african rift show the probelms linked to these dating. The current progresses in the dating methods can contribute by one hand to a better utilization of the K-Ar and fisson track methods for the vulcanic materials. By other hand, with the introduction of new dating methods (thermoluminescence and electron paramagnetic resonance) will be possible to date directly whether the fossil bone itself or the associated sedimentar material. This open new perspectives in particular for every sites which are not inter-stratified with the vulcanic material. (L.C.) [pt

  19. A Phenomenological Investigation of Adolescent Dating Relationships and Dating Violence Counseling Interventions

    Science.gov (United States)

    Hays, Danica G.; Michel, Rebecca E.; Cole, Rebekah F.; Emelianchik, Kelly; Forman, Julia; Lorelle, Sonya; McBride, Rebecca; Sikes, April

    2011-01-01

    Despite the prevalence of dating violence, incidences often go unreported due to a lack of awareness among students as to appropriate dating behaviors. This phenomenology investigated how adolescents conceptualize and experience dating relationships. We explored adolescent females' definitions of healthy and abusive relationships, experiences with…

  20. 20 CFR 404.630 - Use of date of written statement as filing date.

    Science.gov (United States)

    2010-04-01

    ... data on the Internet Social Security Benefit Application to us, we will use the date of the... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Use of date of written statement as filing date. 404.630 Section 404.630 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE...

  1. Development of thermoluminescence dating techniques at Oxford

    International Nuclear Information System (INIS)

    Fleming, S.J.

    1977-01-01

    The two-decade long history of thermoluminescene as a pottery dating method is surveyed with particular reference to the various problems that have been encountered in the Oxford Laboratory's research programme. Effects, such as supralinearity and radon emanation, are explained in terms of how they are measured and how their existence influences thermoluminescence (TL) dating accuracy (currently close to plus minus 7% per analysis). Illustrations of Thermoluminescence (TL) applications include a Nok culture terracotta from Nigeria and a Cambodia bronze Buddha figure of the Khmer period, dated ising the ceramic-like casting-core retained within it. (author)

  2. Some wholesomeness studies on irradiated Iraqi dates

    International Nuclear Information System (INIS)

    Al Rawi, A.M.; Hamoudi, H.I.

    1981-01-01

    Iraqi dates (Zahdi and Khestawi) were irradiated at different dose levels (0 to 1500 krad) to extend their shelf-lives. Samples irradiated at 150 krad showed no change in the behaviour studies of tested Swiss albino mice. Fungi were found to have a constant rate of growth on the syrup irradiated dates. Chemical products such as malondialdehyde, deoxy sugars, acids and reducing sugars were quantified. In conclusion, 150 krad is a convenient dose to extend the shelf-lives of the tested dates and is therefore recommended. (author)

  3. Optically stimulated luminescence dating of young sediments

    DEFF Research Database (Denmark)

    Madsen, Anni Tindahl; Murray, Andrew S.

    2009-01-01

    of OSL dating, outlines the problems specific to the dating of young material, and then uses recent applications to young sediments to illustrate the greatly increased scope and potential of the method in geomorphology and the geology of recent deposits. The overall reliability of this new generation...... for determining the time of deposition of water-lain sediments from the coastal zone, and aeolian deposits from both coastal and inland environments. Our conclusion is supported by the growing popularity of OSL dating in geomorphology and geology...

  4. Annual radiation dose in thermoluminescence dating

    International Nuclear Information System (INIS)

    Li Huhou

    1988-01-01

    The annual radiation dose in thermoluminescence dating has been discussed. The autor gives an entirely new concept of the enviromental radiation in the thermoluminescence dating. Methods of annual dose detemination used by author are dating. Methods of annual dose determination used by author are summed up, and the results of different methods are compared. The emanium escapiug of three radioactive decay serieses in nature has been considered, and several determination methods are described. The contribution of cosmic rays for the annual radiation dose has been mentioned

  5. Annual radiation dose in thermoluminescence dating

    Energy Technology Data Exchange (ETDEWEB)

    Huhou, Li [Chinese Academy of Social Sciences, Beijing, BJ (China). Inst. of Archaeology

    1988-11-01

    The annual radiation dose in thermoluminescence dating has been discussed. The autor gives an entirely new concept of the enviromental radiation in the thermoluminescence dating. Methods of annual dose detemination used by author are dating. Methods of annual dose determination used by author are summed up, and the results of different methods are compared. The emanium escapiug of three radioactive decay serieses in nature has been considered, and several determination methods are described. The contribution of cosmic rays for the annual radiation dose has been mentioned.

  6. Amtrak's strategic business plan : progress to date

    Science.gov (United States)

    1996-07-24

    To address its financial crisis and make its operations more efficient, in 1995 : Amtrak undertook a major corporate restructuring, along with developing its : Strategic Business Plan. This report (1) reviews Amtrak's success to date in : achieving f...

  7. Potassium-argon dating in archaeology

    Energy Technology Data Exchange (ETDEWEB)

    McDougall, I. (Australian National Univ., Canberra (Australia). Research School of Earth Sciences)

    1990-01-01

    The potassium-argon (K-Ar) isotopic dating method can provide precise and accurate numerical ages on suitable rocks, especially igneous rocks, over a wide range of age from less than 100,000 years old, with no older limit. Together with its variants, the {sup 40}Ar/{sup 39}Ar technique, the K-Ar method is very useful for the numerical age calibration of stratigraphic sequences, including those containing archaeological or fossil material, in cases where appropriate rocks for dating are present. This brief review of the basis of the K-Ar dating method and the underlying assumptions, concludes with an example of its application to the Plio-Pleistocene stratigraphic sequence in the Turkana Basin, northern Kenya. By dating alkali feldspars separated from pumice blocks in tuffaceous beds, excellent age control has been obtained for the wealth of vertebrate fossils, including hominids, as well as archaeological materials that has been found in the sequence. (author).

  8. Coconut, date and oil palm genomics

    Science.gov (United States)

    A review of genomics research is presented for the three most economically important palm crops, coconut (Cocos nucifera), date palm (Phoenix dactylifera) and oil palm (Elaeis guineensis), encompassing molecular markers studies of genetic diversity, genetic mapping, quantitative trait loci discovery...

  9. Bullying: a stepping stone to dating aggression?

    Science.gov (United States)

    Josephson, Wendy L; Pepler, Debra

    2012-01-01

    Bullying is the use of power and aggression to control and distress another. In this paper, we review research to explore whether the lessons learned in bullying provide a stepping stone to aggressive behavior in dating relationships. We start by considering definitions and a relationship framework with which to understand both bullying and dating aggression. We consider bullying from a developmental-contextual perspective and consider risk factors associated with the typical developmental patterns for bullying and dating aggression, including developmental and sociodemographic, individual attributes, and family, peer group, community, and societal relationship contexts that might lead some children and youths to follow developmental pathways that lead to bullying and dating aggression. We conclude by discussing implications for intervention with a review of evidence-based interventions.

  10. 38 CFR 21.4135 - Discontinuance dates.

    Science.gov (United States)

    2010-07-01

    ... not leading to a standard college degree is not timely received, payments will be terminated date of... withdraws from correspondence, flight, farm cooperative, cooperative or job training, benefits will be...

  11. Photoassociation spectroscopy of 87Rb2 (5s1/2+5p1/2)0u+ long-range molecular states: Coupling with the (5s1/2+5p3/2)0u+ series analyzed using the Lu-Fano approach

    International Nuclear Information System (INIS)

    Jelassi, H.; Viaris de Lesegno, B.; Pruvost, L.

    2006-01-01

    We report on photoassociation of cold 87 Rb atoms providing the spectroscopy of (5s 1/2 +5p 1/2 )0 u + long-range molecular states, in the energy range of [-12.5, -0.7 cm -1 ] below the dissociation limit. A Lu-Fano approach coupled to the LeRoy-Bernstein formula is used to analyze the data. The Lu-Fano graph exhibits the coupling of the molecular series with the (5s 1/2 +5p 3/2 )0 u + one, which is due to spin effects in the molecule. A two-channel model involving an improved LeRoy-Bernstein formula allows us to characterize the molecular series, to localize (5s 1/2 +5p 3/2 )0 u + levels, to evaluate the coupling, and to predict the energy and width of the first predissociated level of (5s 1/2 +5p 3/2 )0 u + series. An experimental spectrum confirms the prediction

  12. Chlorine-36 dating of continental evaporites

    International Nuclear Information System (INIS)

    Huang Qi

    1990-01-01

    Teh chloring-36 production, principle and experimental method of 36 Cl dating are briefly described. The ages calculated from the 36 Cl/Cl ratios are generally concordant with those obtained by using 14 C, 230 Th and magnetostratigraphic techniques. It confirms the constancy of the chlorine input ratio over the last million years and implys that 36 Cl can provide accurate dates on continental saline sediments

  13. Reduction of date microbial load with ozone

    Science.gov (United States)

    Farajzadeh, Davood; Qorbanpoor, Ali; Rafati, Hasan; Isfeedvajani, Mohsen Saberi

    2013-01-01

    Background: Date is one of the foodstuffs that are produced in tropical areas and used worldwide. Conventionally, methyl bromide and phosphine are used for date disinfection. The toxic side effects of these usual disinfectants have led food scientists to consider safer agents such as ozone for disinfection, because food safety is a top priority. The present study was performed to investigate the possibility of replacing common conventional disinfectants with ozone for date disinfection and microbial load reduction. Materials and Methods: In this experimental study, date samples were ozonized for 3 and 5 hours with 5 and 10 g/h concentrations and packed. Ozonized samples were divided into two groups and kept in an incubator which was maintained at 25°C and 40°C for 9 months. During this period, every 3 month, microbial load (bacteria, mold, and yeast) were examined in ozonized and non-ozonized samples. Results: This study showed that ozonization with 5 g/h for 3 hours, 5 g/h for 5 hours, 10 g/h for 3 hours, and 10 g/h for 5 hours leads to about 25%, 25%, 53%, and 46% reduction in date mold and yeast load and about 6%, 9%, 76%, and 74.7% reduction in date bacterial load at baseline phase, respectively. Appropriate concentration and duration of ozonization for microbial load reduction were 10 g/h and 3 hours. Conclusion: Date ozonization is an appropriate method for microbial load reduction and leads to an increase in the shelf life of dates. PMID:24124432

  14. REPORT ON THE DATING THE ODYSSEY

    OpenAIRE

    r.e. Schmid

    2012-01-01

    STUDY SUPPORTS ACCURACY OF GREEK POET HOMER, SETS DATE FOR ODYSSEUS’ RETURN FROM TROJAN WAR

    Using clues from star and sun positions mentioned by the ancient Greek poet Homer, scholars think they have determined the date when King Odysseus returned from the Trojan War and slaughtered a group of suitors who had been pressing his wife to marry one of them.

  15. Correction procedures for C-14 dates

    International Nuclear Information System (INIS)

    McKerrell, H.

    1975-01-01

    There are two quite separate criteria to satisfy before accepting as valid the corrections to C-14 dates which have been indicated for some years now by the bristlecone pine calibration. Firstly the correction figures have to be based upon all the available tree-ring data and derived in a manner that is mathematically sound, and secondly the correction figures have to produce accurate results on C-14 dates from archaeological test samples of known historical date, these covering as wide a period as possible. Neither of these basic prerequisites has yet been fully met. Thus the two-fold purpose of this paper is to bring together, and to compare with an independently based procedure, the various correction curves or tables that have been published up to Spring 1974, as well as to detail the correction results on reliable, historically dated Egyptian, Helladic and Minoan test samples from 3100 B.C. The nomenclature followed is strictly that adopted by the primary dating journal Radiocarbon, all C-14 dates quoted thus relate to the 5568 year half-life and the standard AD/BC system. (author)

  16. Dating ancient monuments by nuclear radiation

    International Nuclear Information System (INIS)

    Goedicke, C.

    2000-01-01

    In the fifties and sixties several disciplines dealing with chronologies but lacking precise methods of measurements (geology, biology, archaeology and art history) became aware of the radioactive decay as a tool of measuring elapsed time. Among the disciplines that benefit most from physical methods archaeology has to be named first. So was archaeological work revolutionised by the introduction of the C-14 dating method. A wider selection of material became datable after the introduction of luminescence techniques using the effect of nuclear radiation on semiconductors. These minerals are widespread among archaeological materials. In ancient monuments, the objective of this paper, semiconductors almost exclusively form the material basis. Over the last four millennia wood, stone, mortar and fired bricks have been used for the construction of buildings. After discussing methods taking wood as a dating material, a broader view will be given on the results achieved by luminescence dating of fired bricks, mortar and stone. For many years brick dating was performed by thermoluminescence, the recipes followed those of ceramic dating. Preferably multiple aliquot additive dose protocols were used on polymineral fine grain fractions (1-10 μm). It was expected that the error in dating monuments would be smaller compared to ceramic dating, because of the constancy of the environmental conditions which a brick experiences during its lifetime. However, the variability of firing temperatures in brick kilns overthrows this advantage. Therefore, the demands of art historians to fall short of an error margin of 5% could generally not be fulfilled. Especially in medieval or renaissance times the temporal resolution of thermoluminescence is inferior to traditional stylistic dating as long as specific stylistic forms are present. New optical luminescence techniques and a new philosophy of dose evaluation, based on single aliquot regeneration protocols, produce less scatter, and in

  17. Development of BASIC program for radiocarbon dating

    International Nuclear Information System (INIS)

    Omoto, Kunio

    1982-01-01

    The continuous improvement of the system and the needs have produced the successful radiocarbon dating system of today to detect very low energy β-radioactivity. However, it still takes longer than 1,000 minutes for a sample counting. In a gas counting system, it is very difficult to keep the drift of impressed high voltage for a proportional counter less than 5 volts throughout the counting time. The temperature and the characteristics of gas itself also change during experiment. The accumulation of the above drift and errors are closely concerned with the accuracy and reliability of the radiocarbon date. The detection and reduction of the errors are only possible by using a ''fully automatic radiocarbon dating system'' linked to a personal computer system. In this paper, the author presents the BASIC (Beginners All-purpose Symbolic Instruction Code) program for a fully automatic radiocarbon dating system. In this paper, the outline of the system and software development are described. The details of the program include the description for gas-collection, gas-enclosing, plateau counting, β-ray counting, age calculation and data file maintenance. The author wrote numerous remark statements into the program so that it can be understood by users without detailed knowledge of the operation of a personal computer system or of the radiocarbon dating. Using this system, the author found that the radiocarbon dating has greatly progressed in speed and labour-saving, and that the accuracy and reliability of the date itself has also improved much than former manual systems. (Wakatsuki, Y.)

  18. Bullying Predicts Reported Dating Violence and Observed Qualities in Adolescent Dating Relationships.

    Science.gov (United States)

    Ellis, Wendy E; Wolfe, David A

    2015-10-01

    The relationship between reported bullying, reported dating violence, and dating relationship quality measured through couple observations was examined. Given past research demonstrating similarity between peer and dating contexts, we expected that bullying would predict negative dating experiences. Participants with dating experience (n = 585; 238 males, M(age) = 15.06) completed self-report assessments of bullying and dating violence perpetration and victimization. One month later, 44 opposite-sex dyads (M(age) = 15.19) participated in behavioral observations. In 10-min sessions, couples were asked to rank and discuss areas of relationship conflict while being video-recorded. Qualities of the relationship were later coded by trained observers. Regression analysis revealed that bullying positively predicted dating violence perpetration and victimization. Self-reported bullying also predicted observations of lower relationship support and higher withdrawal. Age and gender interactions further qualified these findings. The bullying of boys, but not girls, was significantly related to dating violence perpetration. Age interactions showed that bullying was positively predictive of dating violence perpetration and victimization for older, but not younger adolescents. Positive affect was also negatively predicted by bullying, but only for girls. These findings add to the growing body of evidence that adolescents carry forward strategies learned in the peer context to their dating relationships. © The Author(s) 2014.

  19. Radiocarbon dating of ancient Japanese documents

    International Nuclear Information System (INIS)

    Oda, H.

    2001-01-01

    History is a reconstruction of past human activity, evidence of which is remained in the form of documents or relics. For the reconstruction of historic period, the radiocarbon dating of ancient documents provides important information. Although radiocarbon age is converted into calendar age with the calibration curve, the calibrated radiocarbon age is still different from the historical age when the document was written. The difference is known as 'old wood effect' for wooden cultural property. The discrepancy becomes more serious problem for recent sample which requires more accurate age determination. Using Tandetron accelerator mass spectrometer at Nagoya University, we have measured radiocarbon ages of Japanese ancient documents, sutras and printed books written dates of which are clarified from the paleographic standpoint. The purpose is to clarify the relation between calibrated radiocarbon age and historical age of ancient Japanese document by AMS radiocarbon dating. This paper reports 23 radiocarbon ages of ancient Japanese documents, sutras and printed books. The calibrated radiocarbon ages are in good agreement with the corresponding historical ages. It was shown by radiocarbon dating of the ancient documents that Japanese paper has little gap by 'old wood effect'; accordingly, ancient Japanese paper is a suitable sample for radiocarbon dating of recent historic period. (author)

  20. Date Attachable Offline Electronic Cash Scheme

    Directory of Open Access Journals (Sweden)

    Chun-I Fan

    2014-01-01

    Full Text Available Electronic cash (e-cash is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling.

  1. Auspicious birth dates among Chinese in California.

    Science.gov (United States)

    Almond, Douglas; Chee, Christine Pal; Sviatschi, Maria Micaela; Zhong, Nan

    2015-07-01

    The number eight is considered lucky in Chinese culture, e.g. the Beijing Olympics began at 8:08 pm on 8/8/2008. Given the potential for discretion in selecting particular dates of labor induction or scheduled Cesarean section (C-section), we consider whether Chinese-American births in California occur disproportionately on the 8th, 18th, or 28th day of the month. We find 2.3% "too many" Chinese births on these auspicious birth dates, whereas Whites show no corresponding increase. The increase in Chinese births is driven by higher parity C-sections: the number of repeat C-sections is 6% "too high" on auspicious birth dates. Sons born to Chinese parents account for the entire increase; daughter deliveries do not seem to be timed to achieve "lucky" birth dates. We also find avoidance of repeat C-section deliveries on the 4th, 14th, and 24th of the month, considered unlucky in Chinese culture. Finally, we replicate earlier work finding that Friday the 13th delivery dates are avoided and document a particularly large decrease among Chinese. For Whites and Chinese in California, mothers with higher levels of education are particularly likely to avoid delivering on the 13th. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Date attachable offline electronic cash scheme.

    Science.gov (United States)

    Fan, Chun-I; Sun, Wei-Zhe; Hau, Hoi-Tung

    2014-01-01

    Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling.

  3. ESR dating of the fault rocks

    International Nuclear Information System (INIS)

    Lee, Hee Kwon

    2005-01-01

    We carried out ESR dating of fault rocks collected near the nuclear reactor. The Upcheon fault zone is exposed close to the Ulzin nuclear reactor. The space-time pattern of fault activity on the Upcheon fault deduced from ESR dating of fault gouge can be summarised as follows : this fault zone was reactivated between fault breccia derived from Cretaceous sandstone and tertiary volcanic sedimentary rocks about 2 Ma, 1.5 Ma and 1 Ma ago. After those movements, the Upcheon fault was reactivated between Cretaceous sandstone and fault breccia zone about 800 ka ago. This fault zone was reactivated again between fault breccia derived form Cretaceous sandstone and Tertiary volcanic sedimentary rocks about 650 ka and after 125 ka ago. These data suggest that the long-term(200-500 k.y.) cyclic fault activity of the Upcheon fault zone continued into the Pleistocene. In the Ulzin area, ESR dates from the NW and EW trend faults range from 800 ka to 600 ka NE and EW trend faults were reactivated about between 200 ka and 300 ka ago. On the other hand, ESR date of the NS trend fault is about 400 ka and 50 ka. Results of this research suggest the fault activity near the Ulzin nuclear reactor fault activity continued into the Pleistocene. One ESR date near the Youngkwang nuclear reactor is 200 ka

  4. Date Attachable Offline Electronic Cash Scheme

    Science.gov (United States)

    Sun, Wei-Zhe; Hau, Hoi-Tung

    2014-01-01

    Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling. PMID:24982931

  5. OU3 sediment dating and sedimentation rates

    International Nuclear Information System (INIS)

    Blair, R.B.; Wolaver, H.A.; Burger, V.M.

    1994-01-01

    Environmental Technologies at Rocky Flats Environmental Technology Site (RFS) investigated the sediment history of Standley Lake, Great Western Reservoir, and Mower Reservoir using 137 Cs and 239,240 Pu global fall-out as dating indicators. These Colorado Front Range reservoirs have been the subject of study by various city, state and national agencies due to suspected Department of Energy Rocky Flats Plant impacts. We performed sediment dating as part of the RCRA Facility Investigation/Remedial Investigation Report for Operable Unit 3. A sediment chronology profile assists scientist in determining the year of sedimentation for a particular peak concentration of contaminants. Radioisotope sediment dating for the three reservoirs indicated sedimentation rates of 0.7 to 0.8 in./yr. for Standley Lake (SL), 0.9 in./yr. for Great Western Reservoir (GWR), and 0.3 in./yr. in Mower Reservoir (MR). RFS sediment dating for Operable Unit 3 compared favorably with the Hardy, Livingston, Burke, and Volchok Standley Lake study. This report describes the cesium/plutonium sediment dating method, estimates sedimentation rates for Operable Unit 3 reservoirs, and compares these results to previous investigations

  6. Thermoluminescence of laterites: applicability in dating

    International Nuclear Information System (INIS)

    Sankaran, A.V.; Nambi, K.S.V.; Sunta, C.M.

    1985-01-01

    The northward drift of the Indian subcontinent during the past geological periods brought it under the spell of humid tropical climate in post-mesozoic times which initiated chemical weathering processes (lateritization) of the ancient crustal rocks leading to neomineralization. In the present study, thermoluminescence (TL) of these 'later-formed minerals' has been used to date laterites from a number of localities in India. While the TL emission of most of the laterite samples was poor, three from Kerala, Tamil Nadu and Karnataka states, each derived from mineralogically dissimilar parent rock, yielded measurable TL and provided dates in the range of 2 to 3.6 x 10 5 yr. It is suggested that TL dating can be a promising tool for such samples, and especially those with low alpha activity (U, Th at sub-ppm levels). (author)

  7. Thermoluminescence of laterites: applicability in dating

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran, A V; Nambi, K S.V.; Sunta, C M

    1985-01-01

    The northward drift of the Indian subcontinent during the past geological periods brought it under the spell of humid tropical climate in post-mesozoic times which initiated chemical weathering processes (lateritization) of the ancient crustal rocks leading to neomineralization. In the present study, thermoluminescence (TL) of these 'later-formed minerals' has been used to date laterites from a number of localities in India. While the TL emission of most of the laterite samples was poor, three from Kerala, Tamil Nadu and Karnataka states, each derived from mineralogically dissimilar parent rock, yielded measurable TL and provided dates in the range of 2 to 3.6 x 10/sup 5/ yr. It is suggested that TL dating can be a promising tool for such samples, and especially those with low alpha activity (U, Th at sub-ppm levels).

  8. Geological Survey of Canada radiocarbon dates XXIX

    International Nuclear Information System (INIS)

    McNeely, R.; McCuaig, S.

    1991-01-01

    This list presents 622 radiocarbon age determinations made by the Radiocarbon Dating Laboratory. All samples dated more than two years ago have now been reported in date lists. The total number (609) of samples from various areas are as follows: Offshore (43); Newfoundland (42); Labrador (11); Nova Scotia (39); New Brunswick (7); Champlain Sea (38); Quebec (54); Ontario (23); Manitoba (3); Saskatchewan (9); Alberta (6); British Columbia (92); Yukon Territory (71); Northwest Territories, mainland (33); Northwest Territories, Arctic Archipelago (126); U.S.A. - New York (6); Washington (1); Denmark Greenland (3). Tables 1 and 2 summarize the details of background and standard counts for the 2 L and 5 L counters during the period from December 6, 1988 to January 9, 1990. (author). Refs

  9. Geological Survey of Canada radiocarbon dates XXIX

    Energy Technology Data Exchange (ETDEWEB)

    McNeely, R; McCuaig, S

    1992-12-31

    This list presents 622 radiocarbon age determinations made by the Radiocarbon Dating Laboratory. All samples dated more than two years ago have now been reported in date lists. The total number (609) of samples from various areas are as follows: Offshore (43); Newfoundland (42); Labrador (11); Nova Scotia (39); New Brunswick (7); Champlain Sea (38); Quebec (54); Ontario (23); Manitoba (3); Saskatchewan (9); Alberta (6); British Columbia (92); Yukon Territory (71); Northwest Territories, mainland (33); Northwest Territories, Arctic Archipelago (126); U.S.A. - New York (6); Washington (1); Denmark Greenland (3). Tables 1 and 2 summarize the details of background and standard counts for the 2 L and 5 L counters during the period from December 6, 1988 to January 9, 1990. (author). Refs.

  10. Radiocarbon dating with accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Blake, W. Jr.

    1985-01-01

    Radiocarbon dating by means of accelerator mass spectrometry (AMS) has two great advantages over conventional dating: 1) much smaller samples can be handled and 2) counting time is significantly shorter. Three examples are given for Holocene-age material from east-central Ellesmere Island. The results demonstrate the potential use of this technique as a powerful research tool in studies of Quaternary chronology. Individual fragments of marine shells as small as 0.1 g have been dated successfully at the IsoTrace Laboratory, University of Toronto. In the case of an aquatic moss from a lake sediment core, an increment 0.5 cm thick could be used instead of a 5 cm-thick slice, thus allowing a much more precise estimate of the onset of organic sedimentation

  11. Disinfestation of Date Fruits by Gamma Radiation and Its Effect on the Nutritional Contents of Dates

    International Nuclear Information System (INIS)

    Ahmed, Z.A.; Boshra, S.A.; Mikhaiel, A.A.; Hassan, N.M.

    2008-01-01

    Irradiation dis infestations of Siwa date fruits seems to be a very promising method. Considerations of the health safety of irradiated date fruits involve nutritional contents has been investigated by chemical analysis. The dose of 400 and 1000 Gy were lethal for the different stages of oases date moth, Ephestia calidella. Dates are a good source of iron and potassium, they also contain calcium, magnesium, copper and other minerals. The radiation dose 1000 Gy had mostly affected the carbohydrates content, some minerals as Fe, Ca and Na partially changed by the treatment. Protein and vitamin contents were slightly affected

  12. An assessment of variability in radiocarbon dating

    International Nuclear Information System (INIS)

    Scott, E.M.; Baxter, M.S.; Aitchison, T.C.

    1981-01-01

    A series of replicate experiments, involving analysis of homogenized wood and identical tree-ring sections, suggests that the 14 C counting error in radiocarbon dating quantifies only part of the total variability of measurement. Statistical modelling implies that a more realistic assessment of error is provided by a value approximately three times the counting error. The incorporation of this more realistic measure of variability into an appropriate procedure for calibrating a single date and for matching a floating chronology to a master chronology is described. (author)

  13. Dating Petroglyphs from Fugoppe Cave, Japan

    Directory of Open Access Journals (Sweden)

    Masaru Ogawa

    2014-01-01

    Full Text Available For over 20 years, I have tried to establish a relative date for petroglyphs in Fugoppe Cave, Japan. Unsuspected amidst debris accumulating from about 1300 years ago, the petroglyphs were rediscovered accidentally in 1950. From an analysis of petroglyphs on fallen rocks scattered randomly on the site floor, I argue that the artworks date from ca.1900 years ago. The cave itself, formed by wave action, saw its main occupation by pottery-making people from 1700–1500 years ago; although the petroglyphs on the rock walls predated their occupation, it seems unlikely that the occupants attached any meaning to them.

  14. The TL dating of ancient porcelain

    International Nuclear Information System (INIS)

    Leung, P.L.; Stokes, M.J.; Wang Weida; Xia Junding; Zhou Zhixin

    1997-01-01

    The age determination of ancient porcelain using the pre-dose technique in TL dating was reported. The variation of beta dose with depth below the surface of the porcelain slice, the thermal activation characteristic (TAC) for 110 degree C peak, the measurement of paleodose and the estimation of annual dose were studied. The results show that this technique is suitable for authenticity testing of ancient porcelain, but both accuracy and precision for porcelain dating are worse than those for pottery, because porcelain differs from pottery on composition, structure and firing temperature. Besides, some complicated factors in the pre-dose technique would be the possible cause of the greater errors

  15. Obsidian Hydration Dating in the Undergraduate Curriculum.

    Science.gov (United States)

    Manche, Emanuel P.; Lakatos, Stephen

    1986-01-01

    Provides an overview of obsidian hydration dating for the instructor by presenting: (1) principles of the method; (2) procedures; (3) applications; and (4) limitations. The theory of the method and one or more laboratory exercises can be easily introduced into the undergraduate geology curriculum. (JN)

  16. 29 CFR 1910.98 - Effective dates.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Effective dates. 1910.98 Section 1910.98 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... section, if any standard in 41 CFR part 50-204, other than a national consensus standard incorporated by...

  17. Use of radiocarbon technique for archaelogic dating

    International Nuclear Information System (INIS)

    Chausson, Y.

    1986-01-01

    The nuclear technique based on the beta radiation measurements emitted by the radiocarbon is applied an the geochronologycal dating of organic samples of prehistoric fires and sambaqui shells. This paper describes the origin of the method, the technique used and its applications, the analysis method, the equipments and the experiences performed. (Author) [pt

  18. 77 FR 30928 - Target Date Disclosure

    Science.gov (United States)

    2012-05-24

    ... DEPARTMENT OF LABOR Employee Benefits Security Administration 29 CFR Part 2550 RIN 1210-AB38 Target Date Disclosure AGENCY: Employee Benefits Security Administration, Labor. ACTION: Proposed rule; reopening of comment period. SUMMARY: The Department of Labor's Employee Benefits Security Administration is...

  19. When Pregnancy Goes Past Your Due Date

    Science.gov (United States)

    ... due date determined? • What is postterm pregnancy? • What causes a postterm pregnancy? • What are the risks associated with postterm pregnancy? • ... longer than 42 weeks is called “postterm.” What causes a postterm pregnancy? The causes of postterm pregnancy are unknown, but ...

  20. Radiocarbon dating of interlaboratory check samples

    International Nuclear Information System (INIS)

    Blake, W.

    1983-01-01

    This note presents the results of a series of interlaboratory age determinations in which the Geological Survey of Canada's Radiocarbon Dating Laboratory has been involved. There is good agreement between laboratories, although there may be other problems related to the interpretation of individual samples

  1. Physical Dating Aggression Growth during Adolescence

    Science.gov (United States)

    Nocentini, Annalaura; Menesini, Ersilia; Pastorelli, Concetta

    2010-01-01

    The development of Physical Dating Aggression from the age of 16 to 18 years was investigated in relation to time-invariant predictors (gender, parental education, family composition, number of partners) and to time-varying effects of delinquent behavior and perception of victimization by the partner. The sample consisted of 181 adolescents with a…

  2. 31 CFR 595.302 - Effective date.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Effective date. 595.302 Section 595.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY TERRORISM SANCTIONS REGULATIONS General Definitions...

  3. 50 CFR 216.212 - Effective dates.

    Science.gov (United States)

    2010-10-01

    ..., DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS Taking of Marine Mammals Incidental to Explosive Severance Activities Conducted During Offshore Structure Removal Operations on the Outer Continental Shelf in the U.S. Gulf of Mexico § 216.212 Effective dates...

  4. Date change and safeguards at Dounreay

    International Nuclear Information System (INIS)

    Anderson, A.; Gregory, C.V.

    1999-01-01

    The paper briefly describes the arrangements in Dounreay for tackling the Millennium problem and for managing the accountancy of fissile material. The impact of the date change upon safeguards at Dounreauy has been assessed and the paper shows the problems which have been identified and are being tackled with

  5. Historical Analysis of College Campus Interracial Dating

    Science.gov (United States)

    Firmin, Michael W.; Firebaugh, Stephanie

    2008-01-01

    Interracial dating on American campuses has had a relatively stormy past. Until the past three decades or so, it was outlawed in some states. Southern institutions, in particular, such as the infamous Bob Jones University have made this issue divisive even among their own constituencies. Age and generation seem to be cogent factors with younger…

  6. ESR dating of the fault rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hee Kwon [Kangwon National Univ., Chuncheon (Korea, Republic of)

    2004-01-15

    Past movement on faults can be dated by measurement of the intensity of ESR signals in quartz. These signals are reset by local lattice deformation and local frictional heating on grain contacts at the time of fault movement. The ESR signals then grow back as a result of bombardment by ionizing radiation from surrounding rocks. The age is obtained from the ratio of the equivalent dose, needed to produce the observed signal, to the dose rate. Fine grains are more completely reset during faulting, and a plot of age vs, grain size shows a plateau for grains below critical size : these grains are presumed to have been completely zeroed by the last fault activity. We carried out ESR dating of fault rocks collected near the Ulzin nuclear reactor. ESR signals of quartz grains separated from fault rocks collected from the E-W trend fault are saturated. This indicates that the last movement of these faults had occurred before the quaternary period. ESR dates from the NW trend faults range from 300ka to 700ka. On the other hand, ESR date of the NS trend fault is about 50ka. Results of this research suggest that long-term cyclic fault activity near the Ulzin nuclear reactor continued into the pleistocene.

  7. Radiocarbon dating of ancient rock paintings

    Energy Technology Data Exchange (ETDEWEB)

    Ilger, W.A.; Hyman, M.; Rowe, M.W. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry; Southon, J. [Lawrence Livermore National Lab., CA (United States)

    1995-06-20

    This report presents progress made on a technique for {sup 14}C dating pictographs. A low-temperature oxygen plasma is used coupled with high-vacuum technologies to selectively remove C-containing material in the paints without contamination from inorganic carbon from rock substrates or accretions.

  8. 38 CFR 21.7135 - Discontinuance dates.

    Science.gov (United States)

    2010-07-01

    ...; Pub. L. 98-525) (c) Divorce. If the veteran becomes divorced, the effective date of reduction of his or her educational assistance is the last day of the month in which the divorce occurs. (Authority...) If the veteran or servicemember, for reasons other than being called or ordered to active duty...

  9. Radiocarbon dating of ancient rock paintings

    International Nuclear Information System (INIS)

    Ilger, W.A.; Hyman, M.; Rowe, M.W.

    1995-01-01

    This report presents progress made on a technique for 14 C dating pictographs. A low-temperature oxygen plasma is used coupled with high-vacuum technologies to selectively remove C-containing material in the paints without contamination from inorganic carbon from rock substrates or accretions

  10. The unexpected truth about dates and hypoglycemia

    Directory of Open Access Journals (Sweden)

    Mohammed I Yasawy

    2016-01-01

    Full Text Available Background: Dates are a concentrated source of essential nutrients, vitamins, minerals, and carbohydrates (CHOs, which are necessary for the maintenance of optimum health. Most of the CHOs in dates come from sugars including glucose and fructose. Dates are commonly consumed in Saudi Arabia, particularly at the time of breaking the fast to provide instant energy and maintain blood sugar level. However, dates may cause hypoglycemia in a rare condition named as heredity fructose intolerance (HFI, and a few families have been to see us with a history of that nature. This is to report the preliminary results of an on-going study of a group of patients who get symptoms of hypoglycemia following the ingestion of dates and have suffered for years without an accurate diagnosis. Methodology: This report is based on three patients, from the same family, living in a date growing region of the Kingdom of Saudi Arabia (KSA. The patients had been to several medical centers without getting any definite answers or diagnosis until they were referred to the Gastroenterology Clinic of King Fahd Hospital of the University, Al-Khobar, KSA. The data were obtained by careful history and laboratory investigations, and a final diagnosis of HFI made on fructose intolerance test (FIT. Results: The patients reported that they had avoided eating dates because of various symptoms, such as bloating, nausea, and even hypoglycemia when larger amounts were consumed. Their other symptoms included sleepiness, sweating, and shivering. After full examinations and necessary laboratory tests based on the above symptoms, FIT was performed and the patients were diagnosed with HFI. They were referred to a dietitian who advised a fructose-free diet. They felt well and were free of symptoms. Conclusion: HFI may remain undiagnosed until adulthood and may lead to disastrous complications and even death. The diagnosis can only be suspected after a careful dietary history is taken supported by

  11. Single-machine scheduling with release dates, due dates and family setup times

    NARCIS (Netherlands)

    Schutten, Johannes M.J.; van de Velde, S.L.; van de Velde, S.L.; Zijm, Willem H.M.

    1996-01-01

    We address the NP-hard problem of scheduling n independent jobs with release dates, due dates, and family setup times on a single machine to minimize the maximum lateness. This problem arises from the constant tug-of-war going on in manufacturing between efficient production and delivery

  12. Single-machine scheduling with release dates, due dates, and family setup times

    NARCIS (Netherlands)

    J.M.J. Schutten (Marco); S.L. van de Velde (Steef); W.H.M. Zijm

    1996-01-01

    textabstractWe address the NP-hard problem of scheduling n independent jobs with release dates, due dates, and family setup times on a single machine to minimize the maximum lateness. This problem arises from the constant tug-of-war going on in manufacturing between efficient production and delivery

  13. Internet dating as a project: the commodification and rationalisation of online dating

    Directory of Open Access Journals (Sweden)

    Tjaša Žakelj

    2015-04-01

    Full Text Available Based on qualitative empirical data from two studies on Internet dating in Slovenia, this paper discusses the social contexts of the Internet dating of heterosexual men and women and homosexual men. Special attention is given to different aspects of the commodification and rationalisation of dating in the process of forming potential (romantic partnerships. First, we discuss our respondents’ reasons for using the Internet to get in touch with potential (romantic partners. Second, we focus on the demands and strategies of targeted market- ing in personal profile writing and, finally, on the process of selecting potential partners. Our study shows that the primary understanding of Internet dating among people who engage in it is its economic nature. Together with targeted marketing and the predeter- mined criteria for choosing interesting others, Internet dating can thus be understood as a market that encourages rationalisation and commodification in the process of forming intimate relationships.

  14. Witnessing Interparental Violence and Acceptance of Dating Violence as Predictors for Teen Dating Violence Victimization.

    Science.gov (United States)

    Karlsson, Marie E; Temple, Jeff R; Weston, Rebecca; Le, Vi Donna

    2016-04-01

    We examined the association between witnessing interparental violence, attitudes about dating violence, and physical and psychological teen dating violence (TDV) victimization. Participants were 918 teens with dating experience. Witnessing interparental violence and acceptance of dating violence were significant predictors of TDV victimization. Acceptance of dating violence was also a partial mediator between witnessing interparental violence and TDV victimization. Witnessing mother-to-father violence and acceptance of female-perpetrated violence were the most consistent predictors. TDV programs aiming to prevent victimization could benefit from targeting youth exposed to father-to-mother and mother-to-father violence, targeting attitudes about violence, and tailoring interventions to gender-specific risk factors. © The Author(s) 2015.

  15. Up-Dating: Ratings of Perceived Dating Success Are Better Online than Offline.

    Science.gov (United States)

    Fullwood, Chris; Attrill-Smith, Alison

    2018-01-01

    The primary aims of this study were to test whether perceived dating success would differ between offline and online zero-acquaintance dating contexts and to investigate the role that self-esteem might play in these evaluations. Participants were presented with the same photos of targets in either an offline or online dating scenario and rated their chances of dating success along with their perceptions of how attractive they thought the target would consider them. Higher self-esteem individuals believed they would be rated as more attractive. There was an overall perception that, irrespective of self-esteem level, meeting online would lead to better chances of dating success. These findings are considered in relation to an increased ability to more precisely manage impressions and develop an image of the self which would be evaluated more positively online.

  16. Paleoclimatology: a survey on ancient climates. Volume 1 - To find, date and interpret indices; Volume 2 - To fit the puzzle pieces one to the other: to understand and model a complex system

    International Nuclear Information System (INIS)

    Duplessy, J.C.; Ramstein, G.; Berger, A.; Joussaume, S.; Guillou, H.; Paterne, M.; Michel, E.; Hatte, C.; Dutay, J.C.; Nomade, S.; Scaillet, S.; Frank, N.; Salle, E.; Laj, C.; Channell, J.E.T.; Kissel, C.; Guibal, F.; Guiot, J.; Parrenin, F.; Masson-Delmotte, V.; Jouzel, J.; Rousseau, D.D.; Genty, D.; Von Grafenstein, U.; Belmecheri, S.; Daux, V.; Williamson, D.; Gasse, F.; Vimeux, F.; Cortijo, E.; Labeyrie, L.; Bopp, L.; Friedlingstein, P.; Chappellaz, J.; Legrand, M.; Delmas, R.; Ritz, C.; Peyaud, V.; Waelbroeck, C.; Colleoni, F.; Fluteau, F.; Kageyama, M.; Paillard, D.; Godderis, Y.; Le Hir, G.; Donnadieu, Y.; Roche, D.M.; Combourieu Nebout, N.; Braconnot, P.; Yiou, P.; Charbit, S.; Dufresne, J.L.; Cattiaux, J.

    2013-11-01

    The first volume of this collective publication gathers contributions on techniques used to reconstruct past climates. The chapters address the climate system operation and history (evolution, mechanisms, the atmosphere, oceans, ground and marine biosphere, cryo-sphere, lithosphere), propose an introduction to geochronology, present and discuss various dating methods (carbon 14, K-Ar and Ar-Ar methods, dating of corals and other geological samples based the disequilibrium between uranium and thorium isotopes, use of magnetic stratigraphy, dendro-chronology, dating of ice archives), discuss how to reconstruct atmosphere physics and circulation, address the use and properties of different interfaces (air-ice with polar ices, air-plants with pollen, air-soil with loessic sequences as markers of atmospheric circulation or reconstruction of paleo-climates with speleothems, air-lake, plant-atmosphere, air-plant, air-water, air-ice in tropical glaciers), and discuss the use of paleo-oceanography data. The second volume gathers contributions in which the authors present the most recent approaches used to reconstruct the operation of the climate system in the past by using present observations and models. The chapters address the biochemistry of the climate system during the last million of years, the relationship between cryo-sphere and sea level, the climate at the scale of geological times, modelling approaches in paleoclimatology, the Precambrian climate, the Phanerozoic climates, the relationship between climate and astronomic cycles, the description and mechanisms of quick climate variability, the Holocene and the anthropogenic perturbation, and the evolution from past climates to future climates

  17. Mercury in dated Greenland marine sediments

    DEFF Research Database (Denmark)

    Asmund, G.; Nielsen, S.P.

    2000-01-01

    Twenty marine sediment cores from Greenland were analysed for mercury, and dated by the lead-210 method. In general the cores exhibit a mercury profile with higher mercury concentrations in the upper centimetres of the core. The cores were studied by linear regression of In Hg vs, age of the sedi......Twenty marine sediment cores from Greenland were analysed for mercury, and dated by the lead-210 method. In general the cores exhibit a mercury profile with higher mercury concentrations in the upper centimetres of the core. The cores were studied by linear regression of In Hg vs, age...... indicating that the mercury mainly originates from atmospheric washout. But the large variability indicates that other processes also influence the mercury flux to Arctic marine sediments. (C) 2000 Elsevier Science B.V. All rights reserved....

  18. 210Pb dating of Baltic Sea sediments

    International Nuclear Information System (INIS)

    Gellermann, R.

    1990-01-01

    The paper reports on the results of 210 Pb measurement in sediment cores from the Baltic Sea. The models used for the interpretation are derived and discussed. In general, the sedimentation parameters calculated with different models are consistent. However, parameters of cores independently taken on same partly show clearly differing values. The reasons of this observation have to be analysed by further studies. An essential problem considered in this paper is the dating of disturbed sediments. The use of such cores for the reconstruction of the input history of chemical indicators requires a deconvolution of data. The response function necessary for this procedure can be derived from 210 Pb measurements. The results of such a reconstruction considerably differ from those obtained by conventional dating models. The analysis of the measuring uncertainty of the indicator (e.g. lead) in the deconvolution procedure unveals the limits of the method and prevents it from overinterpretation. (orig.) [de

  19. Dating methods and their relevance in physics

    International Nuclear Information System (INIS)

    Schneider, H.

    1981-01-01

    The article describes some of the most important radiometric clocks. It is pointed out how much the chronological interpretation of isotopic ratios depends on preconceived models about origin and history of investigated minerals. A number of physico-chemical effects are discussed, which give rise to fictitious datings. The possibility is considered that all the radiometric ages used for establishing the geologic time scale might be due to such effects. The history and foundations of the latter are reviewed, and the possibility of a wrong decision is mentioned. Several results from fossil objects indicate very young ages. The usual treatment of anomalous results is criticised. Long-time clocks fails to reproduce documented young ages. It is suggested that in the age interpretation of isotopic ratios much younger than conventional ages be also taken into consideration. The importance of directly dating fossils is stressed. (orig./HP) [de

  20. Radiocarbon dating development and practices at MINT

    International Nuclear Information System (INIS)

    Kamisah Alias; Bashillah Baharuddin; Juhari Mohd Yusof; Ahmad Raduan Ujang

    2002-01-01

    The MINT radiocarbon dating technique was introduced and a very well-designed vacuum line was developed to generate benzene from samples containing carbon. A liquid scintillation counter provides a very good prerequisite for precise measurement of the C-14 activity in the benzene. From time to time, assessment on the status of the analytical capabilities of the system and advice on improvement and upgrading required was made. For routine analysis, standard sampling, pretreatment, carbon dioxide conversion and measurement procedures were adopted. Radiocarbon dating is now, one of the most important developments of the twenties century in the comprehension of the history of human development, a quick, easy, reliable and scientifically acceptable method to determine the age of historical artefacts and archaeological samples. (Author)

  1. Perspectives in radiocarbon dating by radiometry

    International Nuclear Information System (INIS)

    Polach, H.A.

    1987-01-01

    Opportunities for individual contributions to the technology of radiocarbon dating over the past 40 years have been large. Meaningful developments are traced in this review of C-14 dating by gas proportional (GP) and liquid scintillation (LS) spectrometry. The performance of characteristic as well as state of the art GP and LS systems is tabulated and their merit for low-level counting of C-14 is evaluated. Future developments in radiometry will lie in the updating of existing systems to incorporate new technologies and the refinement of resolution and identification of extreme low-level signals. Parallel development with AMS, sharing on merit the ever widening applied C-14 research field, and enhanced interdisciplinary collaboration are foreseen as the scenario leading to the year 2000

  2. Perspectives in radiocarbon dating by radiometry

    International Nuclear Information System (INIS)

    Polach, H.A.

    1987-01-01

    Opportunities for individual contributions to the technology of radiocarbon dating over the past 40 years have been large. Meaningful developments are traced in this review of C-14 dating by gas proportional (GP) and liquid scintillation (LS) spectrometry. The performance of characteristic as well as state of the art GP and LS systems is tabulated and their merit for low-level counting of C-14 is evaluated. Future developments in radiometry will lie in the updating of existing systems to incorporate new technologies and the refinement of resolution and identification of extreme low-level signals. Parallel development with AMS, sharing on merit the ever widening applied C-14 research field, and enhanced interdisciplinary collaboration are foreseen as the scenario leading to the year 2000. (orig.)

  3. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    case studies will show the degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants and animals, shows that age differences of up to 2000 years can occur within one river. In the Limfjord, freshwater influence......The freshwater reservoir effect can result in too high radiocarbon ages of samples from lakes and rivers, including the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. In my talk, I will explain the causes and consequences of this effect. Two...... caused reservoir ages to vary between 250 and 700 years during the period 5400 BC - AD 700. Finally, I will discuss the implications of the freshwater reservoir effect for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany....

  4. Towards Luminescence Dating Of Mosaic Glass

    Science.gov (United States)

    Galli, A.; Martini, M.; Sibila, E.; Villa, I.

    The possibility of dating archaeological glass by means of luminescent techniques has been investigated in recent years, despite the difficulties of this application, mainly linked to the amorphous structure of the material. We focused in particular on mosaic glass, after the encouraging results obtained on byzantine and medieval samples. Further studies were devoted to the comprehension of the luminescent mechanisms in silica glasses, and to the investigation of the relationships between luminescence, colouring or opacifier ions and crystalline phase of the vitreous matrix. The results of a study on the dosimetric characteristics of thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) of a few medieval blue-green mosaic glasses from the San Lorenzo church (Milan) are presented, and the experimental protocols established to identify their suitability for dating are discussed.

  5. AGAR PENULISAN RESEP TETAP UP TO DATE

    Directory of Open Access Journals (Sweden)

    Rahmatini Rahmatini

    2009-09-01

    Full Text Available AbstrakResep adalah suatu permintaan tertulis dari dokter, dokter gigi atau dokter hewan kepada apoteker untuk membuatkan obat dalam bentuk sediaan tertentu dan menyerahkannya kepada pasien. Resep merupakan perwujudan akhir dari kompetensi, pengetahuan dan keahlian dokter dalam menerapkan pengetahuannya dalam bidang farmakologi dan terapi.Penulisan resep harus ditulis dengan jelas sehingga dapat dibaca oleh petugas di apotek. Resep yang ditulis dengan tidak jelas akan menimbulkan terjadinya kesalahan saat peracikan / penyiapan obat dan penggunaan obat yang diresepkan.Ilmu pengetahuan tentang obat selalu berubah, obat – obat baru selalu muncul di pasaran.Secara umum, seorang dokter harus mengikuti perkembangan dalam terapi obat. Bila muncul efek samping akibat obat yang seharusnya diketahui dan dapat dicegah oleh dokter, maka dokter akan berhadapan dengan hukum.Agar penulisan resep tetap up to date, seorang dokter harus mengumpulkan berbagai informasi yang tersedia. Sumber informasi yang dapat digunakan adalah : Buku acuan, Kompendium obat, Daftar Obat Esensial Nasional (DOEN dan Pedoman terapi, Buletin obat, Jurnal Kedokteran, Pusat informasi obat,Informasi melalui komputer, Sumber informasi dari industri farmasi, dan informasi lisan.Bandingkan kelebihan dan kekurangan berbagai sumber informasi. Tugas seorang dokter adalah melakukan cara terbaik untuk tetap up to date dengan mendaftar sumber informasi yang dapat dimanfaatkan. Carilah sedikitnya satu dari yang berikut ini : (1 jurnal kedokteran: (2 buletin obat; (3 buku acuan farmakologi atau acuan klinis; (4 komisi terapi maupun konsultan, atau lulusan pasca sarjana farmakologi. Dengan bekal pengetahuan dan kemampuan untuk melakukan penilaian secara kritis setiap bentuk informasi, diharapkan dokter tetap up to date dalam menulis resepKata kunci : Resep – up to- date.Abstract Prescription is a written request from a doctor, dentist or veterinarian to the pharmacist to make a particular drug

  6. Radiocarbon dating methods using benzene liquid scintillation

    International Nuclear Information System (INIS)

    Togashi, Shigeko; Matsumoto, Eiji

    1983-01-01

    The radiocarbon dating method using benzene liquid scintillation is reported in detail. The results of measurement of NBS oxalic acid agree with the recommended value, indicating that isotopic fractionation during benzene synthesis can be negligible. Ten samples which have been already measured by gas counter are dated by benzene liquid scintillation. There is no significant difference in age for the same sample between benzene liquid scintillation and gas counters. It is shown that quenching has to be corrected for the young sample. Memory effect in stainless steel reaction vessel can be removed by using an exchangeable inner vessel and by baking it in the air. Using this method, the oldest age that can be measured with 2.3 g carbon is 40,000 years B.P. (author)

  7. William Crabtree and the date of Easter

    Science.gov (United States)

    Sellers, D.

    2014-04-01

    A previously unknown treatise by William Crabtree (c.1603-c.1644) has recently been unearthed in the Lancashire Record Office. The treatise, in manuscript form and written in 1640, deals with the controversy over the long-term impact of the Julian Calendar - then in use in England - upon the ecclesiastical dating of Easter. By Crabtree's time, the timing of the Easter celebration in England was often several weeks adrift of the intentions of the early Church Fathers. The Gregorian Calendar, which Roman Catholic countries had adopted as long ago as 1582 in order to resolve the problem, was still vehemently resisted by the English state. This is possibly the only surviving manuscript in Crabtree's own hand. In it, he displays noteworthy dispassionate objectivity as he outlines the astronomical basis for the Easter date and explains why it has gone awry.

  8. Evaluation of the commercial FBR introduction date

    International Nuclear Information System (INIS)

    White, M.K.; Merrill, E.T.

    1981-09-01

    This report examines one criterion for introducing a commercial FBR: economic competitiveness with a Light Water Reactor (LWR). For this analysis, the commercial FBR is assumed to be the fifth-of-a kind replicate which represents an economically mature plant. This FBR is deemed economically competitive when its life-cycle energy cost is less than or equal to that of an LWR. Results of this analysis are used in a comparative analysis of alternative FBR development stategies. The strategies evaluated in these studies assume both 1000- and 1457-MWe FBRs. Since the capital costs per kilowatt, and therefore the energy costs, for these two FBR sizes are different, they will become economically competitive at different times. The probability density function for the 1457-MW(e) FBR has an expected value date or weighted average date of 2030, compared with 2033 for the probability density function for the 1000-MW(e) FBR

  9. Carbon-14 Bomb-Pulse Dating

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A

    2007-12-16

    Atmospheric testing of nuclear weapons during the 1950s and early 1960s doubled the concentration of carbon-14 atmosphere and created a pulse that labeled everything alive in the past 50 years as carbon moved up the food chain. The variation in carbon-14 concentration in time is well-documented and can be used to chronologically date all biological materials since the mid-1950s.

  10. Radiocarbon dating for the Quaternary scientist

    International Nuclear Information System (INIS)

    Pilcher, J.R.

    1991-01-01

    The accuracy of many conventional and accelerator mass spectrometry (AMS) radiocarbon dates is not adequate for the sort of questions now being asked in Quaternary studies. The need for, and effects of, radiocarbon calibration are discussed and guide-lines offered for the selection of a laboratory. High precision laboratories and the use of wiggle matching will go a long way to answering the critical questions of rates of change and durations of events in the Holocene. (Author)

  11. Progress and problems with automated TL dating

    International Nuclear Information System (INIS)

    McKerrell, H.; Mejdahl, V.

    1981-01-01

    A number of basic problems connected with the measurement of beta and gamma dose-rates are discussed, and the possibility of using low-temperature peaks in quartz and feldspar for dose-rate measurements is examined. Preliminary results of TL measurements on individual grains of quartz and feldspar are presented. A TL dating method based on the difference in the archaeological dose received by potassium feldspar and quartz grains is proposed. (author)

  12. Dating cremated bone: the scientific background

    Directory of Open Access Journals (Sweden)

    Lanting, J. N.

    1999-12-01

    Full Text Available A new method of obtaining absolute chronology dates out of burnt or cremated bone is presented. The authors explain their recent experiments and give promising results.

    Los autores presentan un nuevo método para obtener fechas de datación absoluta a partir de restos de hueso sometidos a diferentes grados de combustión y explican algunas de sus recientes experiencias y los resultados obtenidos.

  13. Violence in dating: An update for adolescence

    OpenAIRE

    Valdivia Peralta, Maruzzella Paola; González Bravo, Luis Antonio

    2014-01-01

    This literature review updates evidence about intimate partner violence in dating relationships, revealing a particular phenomenon, emphasizing issues such as the prevalence for both sexes, which according to various reviewed studies may range from 0.8% for sexual violence to 98% for psychological aggression. Factors associated with abuse or early sexual initiation, temporal extent of the relationship, role of parents and peers, among others; and the consequences as dropouts: teenage pregnanc...

  14. Date Sensitive Computing Problems: Understanding the Threat

    Science.gov (United States)

    1998-08-29

    equipment on Earth.3 It can also interfere with electromagnetic signals from such devices as cell phones, radio, televison , and radar. By itself, the ...spacecraft. Debris from impacted satellites will add to the existing orbital debris problem, and could eventually cause damage to other satellites...Date Sensitive Computing Problems Understanding the Threat Aug. 17, 1998 Revised Aug. 29, 1998 Prepared by: The National Crisis Response

  15. Progress in ESR dating of fossils

    International Nuclear Information System (INIS)

    Ikeya, M.

    1983-01-01

    In this review the progress of ESR dating is briefly described together with its historical development. Examples of fossil dating include shells and corals in geological sediments, fossil bones and teeth in anthropology and fossil woods in geology. The total dose of natural radiation (TD) equivalent to the archaeological dose in TL dating was obtained by the additive dose method. Initially, the TDs were plotted against the known ages; using the apparent annual dose-rate thus obtained gives the ESR age within a factor of 2 or 3 for a fossil. Precise assessment of the radiation environment was made later taking the disequilibrium of uranium series disintegration into account. ESR ages of corals agreed well with those obtained by radiocarbon and uranium-thorium methods. The time-independent accumulation rate or a linear accumulation or uranium was adopted as a first sensible model for the opensystem fossil bones: the relation between the TD and the age explains the ages of anthropologically important bones. Lastly, geological assessment of fossil woods was made by ESR based on the organic radicals and electron traps in the silicified part. (author)

  16. Dates as raw material for agricultural distilleries

    Energy Technology Data Exchange (ETDEWEB)

    Laczynski, B

    1971-01-01

    Pit-containing dates had 88.0 to 89.2% dry matter, 41.7 to 47.5% sucrose, and 2.1 to 2.9% total protein. The mechanical broken charges of raw material were steamed, dispersed to a suspension of 15 to 17/sup 0/ Balling and pH 4.8 to 5.0, enriched with P and N, inoculated with 5 to 7 % of yeast suspension, and acidified to pH > 3.5. Thermophilic yeast cultivated at 27/sup 0/ and fermented below 30/sup 0/ for 2 days gave best results. The fermented liquor had a pH > 3.5, apparent density of 2.0/sup 0/, and contained 7.5 to 9.0 EtOH. From 100 kg dates were obtained 280 t0 340 l of the 15 to 17/sup 0/ dispersion and 320 to 360 l residue containing (per l) 6.0 to 8.5 g protein and 0.04 oat units. EtOH yield (l/quintal) was 914 for potatoes, 28.54 for molasses, 36.29 for cereals, 25.15 for dates, and 18.53 for malt.

  17. Preference Versus Choice in Online Dating.

    Science.gov (United States)

    Whyte, Stephen; Torgler, Benno

    2017-03-01

    This study explores factors that influence matches of online dating participants' stated preference for particular characteristics in a potential partner and compares these with the characteristics of the online daters actually contacted. The nature of online dating facilitates exploration of the differences between stated preference and actual choice by participants, as online daters willingly provide a range of demographics on their ideal partner. Using data from the Australian dating website RSVP, we analyze 219,013 contact decisions. We conduct a multivariate analysis using the number of matched variables between the participants' stated preference and the characteristics of the individuals contacted. We find that factors such as a person's age, their education level, and a more social personality all increase the number of factors they choose in a potential partner that match their original stated preference. Males (relative to females) appear to match fewer characteristics when contacting potential love interests. Conversely, age interaction effects demonstrate that males in their late 60's are increasingly more selective (than females) regarding who they contact. An understanding of how technology (the Internet) is impacting human mating patterns and the psychology behind the participants informs the wider social science of human behavior in large-scale decision settings.

  18. Radiocarbon C-14 dating - MINT experience

    International Nuclear Information System (INIS)

    Kamisah Alias

    2002-01-01

    The measurement of a radiocarbon date is a complex process which involved all the stages from advice given prior to submission of samples right through to reporting of results. The aim of our radiocarbon dating is to determine the residual 14 C content of a sample, the value of which is translated into an age that is an estimate of the time elapsed since the given sample was removed from the environment in which it had formed in equilibrium with respect to 14-C radioactive decay and metabolic assimilation. Carbon is obtained from carbon containing samples in the form of carbon dioxide, which is then reacted with lithium forming lithium carbide. The carbide is then hydrolysed to acetylene before it was polymerised to benzene using a high-efficiency vanadium-alumina-silica catalyst to produce benzene with up to 96% yield. Sample, background and modem standard activities are measured with a coincidence scintillation counter using in glass vials of 21 ml capacity. An improved chemical procedure was used to obtain and purify the benzene from the samples for measurement using a liquid scintillation counter. Radiocarbon dating measurements of samples collected reveal some results. The validity of the data have yet to be confirmed by the results of the measurements on two international control samples. (Author)

  19. Low energy cyclotron for radiocarbon dating

    International Nuclear Information System (INIS)

    Welch, J.J.

    1984-12-01

    The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity 14 C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate 14 C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect 14 C directly at modern concentrations. We show how a conventional carbon negative ion source, located outside the cyclotron magnet, would produce sufficient beam and provide for quick sampling to make radiocarbon dating milligram samples with a modest laboratory instrument feasible

  20. Environmental history and dating of coastal dunefields

    International Nuclear Information System (INIS)

    Illenberger, W.K.; Verhagen, B.T.

    1990-01-01

    Sand pulses can be inferred from the geomorphologic evolution of coastal dunefields over the last 6500 years in the eastern Cape Province, South Africa. These pulses correlate with erosion cycles and variation in sea-level, temperature and effective moisture. The concept that sand dunes have a wind memory and represent a record of the wind that blew to produce them can be modified and applied to dunefields: the morphology of dunefields represents an environmental record, going back thousands of years. The carbonate content of eastern Cape coastal sands is biogenic with young coarse carbonate grains constantly being added to the system, resulting in a pronounced negative correlation of radiocarbon age with grain size. It takes thousands of years for an average mollusc shell to be broken to 1-mm-diameter fragments, and a further couple of thousand years to break these sizes down to 0.2-0.3 mm diameter. Eastern Cape coastal dunefields have for the first time been dated definitively via the radiocarbon ages of the carbonate component of the sand. These dunefields have been forming during the past 5000 years or so. Dating wind-blown sand transport is feasible, and correlates with dates inferred from the dunefield morphology. 5 figs., 1 tab., 18 refs

  1. Production of baker's yeast using date juice.

    Science.gov (United States)

    Beiroti, A; Hosseini, S N

    2007-07-01

    Baker's yeast is an important additive among the products which improves bread quality and for present time is being produced in different countries by batch, fed batch or continuous cultures. Saccharomyces cerevisiae is used in fermentation of starch in dough, giving a favourable taste and produces a variety of vitamins and proteins. The main ingredient in yeast production is carbon source such as beet molasses, cane molasses, and so on. Since beet molasses has other major function as in high yield alcohol production and also due to the bioenvironmental issues and related wastewater treatment, the use of other carbohydrate sources may be considered. One of these carbohydrate sources is date which is wasted a great deal annually in this country (Iran) . In this study, the capability of date to act as a suitable carbon sources was investigated. The waste date turned into juice and consequently production and growth rate of Sacchromyces cervisiae were studied with this juice. A maximum possible yield of 50% was obtained by the optimum medium (P3), at pH 3.4, 30 degrees C, 1.4 vvm aeration rate and agitation of 500 r/min.

  2. 17 CFR 232.13 - Date of filing; adjustment of filing date.

    Science.gov (United States)

    2010-04-01

    ..., shall not affect the date of filing. (2) If the conditions of paragraph (a)(1) of this section are... and consistent with the public interest and the protection of investors. (c) Payment of fees. Fees...

  3. 12 CFR 717.28 - Effective date, compliance date, and prospective application.

    Science.gov (United States)

    2010-01-01

    ... REGULATIONS AFFECTING CREDIT UNIONS FAIR CREDIT REPORTING Affiliate Marketing § 717.28 Effective date... eligibility information that you receive from an affiliate to make solicitations to a consumer if you receive...

  4. 12 CFR 334.28 - Effective date, compliance date, and prospective application.

    Science.gov (United States)

    2010-01-01

    ... REGULATIONS AND STATEMENTS OF GENERAL POLICY FAIR CREDIT REPORTING Affiliate Marketing § 334.28 Effective date... eligibility information that you receive from an affiliate to make solicitations to a consumer if you receive...

  5. Date canning: a new approach for the long time preservation of date.

    Science.gov (United States)

    Homayouni, Aziz; Azizi, Aslan; Keshtiban, Ata Khodavirdivand; Amini, Amir; Eslami, Ahad

    2015-04-01

    Dramatic growth in date (Phoenix dactylifera L.) production, makes it clear to apply proper methods to preserve this nutritious fruit for a long time. Numerous methods have been used to gain this goal in recent years that can be classified into non-thermal (fumigation, ozonation, irradiation, and packaging) and thermal (heat treatment, cold storage, dehydration, jam etc.) processing methods. In this paper these methods were reviewed and novel methods for date preservation were presented.

  6. Last Deglaciation Events (16.1-11.4 cal-Ka) Recorded in a Speleothem from DeSoto Caverns, Alabama, U.S.A.

    Science.gov (United States)

    Lambert, W. J.; Aharon, P.; Hellstrom, J.

    2007-12-01

    Whereas the rapid climate swings that occurred during the last deglaciation have been well documented in the Greenland ice cores, their cause/s continue to be a subject of heated debate. Clearly, more geographically dispersed records are required in order to provide better insight into the history of deglaciation, and by extension into the cause/s of the abrupt climate shifts. Particularly scarce are continental deglaciation records from the southeast North America whose atmospheric conditions were controlled by the retreating Laurentide Ice Sheet to the north and the Gulf of Mexico warm waters to the south. In order to remedy the absence of deglaciation records in the Southeast USA in general, and the Gulf Coast in particular, we have initiated a study of a 55-cm long stalagmite (DSSG-2) from the DeSoto Caverns in Childersburg, Alabama (33° 18'N, 86° 17'W). Seven radiocarbon AMS and eighteen U/Th TIMS dates reveal that the continuously layered stalagmite covers the time interval 31 to 11.4 cal-Ka at growth rates varying from 61 μm/decade at the start of deglaciation and up to 2700 μm/decade close to its termination. The combination of unusually high growth rates, pristine aragonite mineralogy and tight sampling (n=602) afforded generation of high fidelity δ13C and δ18O records from about 16.1 to 11.4 cal-Ka whose high resolution is comparable with the contemporaneous Greenland ice core records. The stalagmite δ18O record shows excellent agreement in relative amplitude shifts and timing of abrupt and brief cold reversals (Oldest Dryas, Older Dryas, Inter-Allerød Cold Period) that punctuated the overall trend of deglaciation warming (Bølling/Allerød period). The succeeding Younger Dryas is depicted in the stalagmite by rapid positive shifts in δ18O and δ13C of 1.3‰ and 2.3‰ (V-PDB) relative to the baseline mean value and its start and termination (12.7-11.8 Ka) are concordant within error with the dates reported from GISP2 ice core (12.82-11.60 Ka

  7. Fission track dating of kimberlitic zircons

    International Nuclear Information System (INIS)

    Haggerty, S.E.

    1983-01-01

    The only reliable method for dating kimberlites at present is the lengthy and specialized hydrothermal procedure that extracts 206 Pb and 238 U from low-uranium zircons. This paper describes a second successful method by fission track dating of large single-crystal zircons, 1.0-1.5 cm in dimension. The use of large crystals overcomes the limitations imposed in conventional fission track analysis which utilizes crushed fragments. Low track densities, optical track dispersion, and the random orientation of polished surfaces in the etch and irradiation cycle are effectively overcome. Fission track ages of zircons from five African kimberlites are reported, from the Kimberley Pool (90.0 +- 6.5 m.y.), Orapa (87.4 +- 5.7 and 92.4 +- 6.1 m.y.), Nzega (51.1 +- 3.8 m.y.), Koffiefontein (90.9 +- 8.2 m.y.), and Val do Queve (133.4 +- 11.5 m.y.). In addition we report the first radiometric ages (707.9 +- 59.6 and 705.5 +- 61.0 m.y.) of crustal zircons from kimberlites in northwest Liberia. The fission track ages agree well with earlier age estimates. Most of the zircons examined in this study are zoned with respect to uranium but linear correlations are established (by regression analysis) between zones of variable uranium content, and within zones of constant uranium content (by analysis of variance). Concordance between the fission track method and the U/Pb technique is established and we concluded that track fading from thermal annealing has not taken place. Kimberlitic zircons dated in this study, therefore, record the time of eruption. (orig.)

  8. 24 CFR 220.811 - Date of default.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Date of default. 220.811 Section... and Obligations-Projects Insured Project Improvement Loans § 220.811 Date of default. For the purposes of §§ 220.800 et seq., the date of default shall be considered as: (a) The date of the first...

  9. Date fruit: chemical composition, nutritional and medicinal values, products.

    Science.gov (United States)

    Tang, Zhen-Xing; Shi, Lu-E; Aleid, Salah M

    2013-08-15

    Date fruit has served as a staple food in the Arab world for centuries. Worldwide production of date fruit has increased almost threefold over the last 40 years, reaching 7.68 million tons in 2010. Date fruit can provide many essential nutrients and potential health benefits to the consumer. Date fruit goes through four ripening stages named kimri, khalal, rutab and tamer. The main chemical components of date fruit include carbohydrates, dietary fibre, enzymes, protein, fat, minerals, vitamins, phenolic acids and carotenoids. The chemical composition of date fruit varies according to ripening stage, cultivar, growing environment, postharvest conditions, etc. The nutritional and medicinal activities of date fruit are related to its chemical composition. Many studies have shown that date fruit has antioxidant, antimutagenic, anti-inflammatory, gastroprotective, hepatoprotective, nephroprotective, anticancer and immunostimulant activities. Various date fruit-based products such as date syrup, date paste, date juice and their derived products are available. Date by-products can be used as raw materials for the production of value-added products such as organic acids, exopolysaccharides, antibiotics, date-flavoured probiotic-fermented dairy produce, bakery yeasts, etc. In this paper the chemical composition and nutritional and medicinal values of date fruit as well as date fruit-based products are reviewed. © 2013 Society of Chemical Industry.

  10. Dating Violence among High School Students in Southeastern North Carolina

    Science.gov (United States)

    Kim-Godwin, Yeoun Soo; Clements, Carrie; McCuiston, Ashley M.; Fox, Jane A.

    2009-01-01

    Adolescents are a high-risk group for dating violence. Using the Youth Risk Behavior Survey data, this study examined the associations among dating violence (including physical dating violence [PDV] and sexual dating violence [SDV]) and selected health risk behaviors among 375 and 372 high school students, in 2005 and 2007, respectively, in…

  11. 7 CFR 35.8 - Date of export.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Date of export. 35.8 Section 35.8 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS EXPORT GRAPES AND PLUMS Definitions § 35.8 Date of export. Date of export means the date of loading on board the...

  12. 21 CFR 610.50 - Date of manufacture.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Date of manufacture. 610.50 Section 610.50 Food... GENERAL BIOLOGICAL PRODUCTS STANDARDS Dating Period Limitations § 610.50 Date of manufacture. The date of manufacture shall be determined as follows: (a) For products for which an official standard of potency is...

  13. Uses of radiocarbon dating in archaeology

    International Nuclear Information System (INIS)

    Purohit, Anila; Bishnoi, Indra; Charan, Sumitra

    2012-01-01

    Carbon dating is one of the mist effective tools in the archaeologist's kit. It has provided illumination where none was once thought possible. The historians of one hundred years ago could only dream of such a wonderful, albeit frightening atomic clock ticking away, helping to mark the passing of the years and the ages of man. It is a vital part in the investigation and preservation of our past and a lovely bit of analysis to compliment digital records of monuments. It places the plants, animals, and people of yore into an understandable and verifiable context

  14. Dating method with /sup 39/Ar

    Energy Technology Data Exchange (ETDEWEB)

    Loosli, H H [Bern Univ. (Switzerland). Physikalisches Inst.

    1983-04-01

    The principles of a dating method based on the cosmic-ray-produced radioisotope /sup 39/Ar are given. Technical requirements such as background and standard gas samples and gas proportional counting systems are described. With samples extracted from Greenland ice it can be demonstrated that /sup 39/Ar ages agree with ages obtained by other methods. First results on ocean water samples show that with this isotope valuable information on ocean mixing and circulation can be expected. /sup 39/Ar results on groundwater samples disagree for some aquifers with conventional /sup 14/C ages; possible explanations are discussed, especially underground production of /sup 39/Ar.

  15. Radiocarbon dating prehistoric pottery from Northern Europe

    DEFF Research Database (Denmark)

    Philippsen, Bente; Craig, Oliver; Heron, Carl

    2012-01-01

    , such as when aquatic products have been prepared in the pottery. Soot can derive from old wood that was used for the hearth fire, or from (potentially aquatic) food that boiled over. Plant remains may have been present in the clay for a long time before manufacture of the pottery. Post......-depositional contamination with organic carbon, such as humic acids, may also be problematic. We present these data with radiocarbon datings of contemporaneous terrestrial and aquatic samples to find out the true age of the pottery and estimate the reservoir age. Lipid analysis and bulk carbon and nitrogen stable isotope...

  16. Suitability of Ostrich eggshell for radiocarbon dating

    CSIR Research Space (South Africa)

    Vogel, JC

    2001-01-01

    Full Text Available deposits cannot be guaranteed. A more direct approach would be to ana- lyze modern ostrich eggs of which the date of laying is known. It is necessary to know exactly when the eggs were laid because the elevated 14C content of the environment caused... sample we also analyzed the organic contents of the egg—a mixture of the egg white and yolk. Also given is the 14C content of the carbon dioxide of the atmosphere in the month in which the eggs were laid. This closely reflects the 14C content...

  17. Zechariah and the Dating of Biblical Hebrew

    DEFF Research Database (Denmark)

    Ehrensvärd, Martin Gustaf

    2006-01-01

    The data presented in the article indicate clearly that the ability to write proper EBH did not end with the exile; but when did it end? In the course of the fifth century, or the fourth century, or even later? This is difficult to resolve, on linguistic grounds. On linguistic grounds, can we say...... conclusions of most biblical scholars. Considering only linguistic data, texts in EBH could have been composed after the exile. Other, non-linguistic considerations can make this unlikely, but we can raise no objections from a linguistic viewpoint to such a dating....

  18. Thermoluminescence dating of some Hungarian medieval churches

    International Nuclear Information System (INIS)

    Kasa, I.; Bajnoczy, G.

    1984-01-01

    Thermoluminescence dating of three Hungarian historic churches was performed using the quarz inclusion technique and sup(60)Co gamma irradiation. Quarz grains obtained from the bricks were irradiated and the radiation doses were measured by CaSOsub(4):Dy TL dosemeters. Glow curves of irradiated and non-irradiated samples were also measured. From the results it was concluded that the ages of two churches were 10 and 30 percent less, respectively, than the ages estimated earlier. The age of the third church proved to be correct. (R.P.)

  19. Optically stimulated luminescence dating of rock surfaces

    DEFF Research Database (Denmark)

    Sohbati, Reza

    There are many examples of rock surfaces, rock art and stone structures whose ages are of great importance to the understanding of various phenomena in geology, climatology and archaeology. Optically stimulated luminescence (OSL) dating is a well-established chronological tool that has successfully...... to include the effects of the environmental dose rate. By fitting the model to the dose-depth variation from a single clast, four events (two light exposures of different durations each followed by a burial period) in the history of a single cobble are identified and quantified. However, the use of model...

  20. K/Ar dating of diagenetic illites

    International Nuclear Information System (INIS)

    Mizusaki, A.M.P.; Anjos, S.M.C. dos; Costa, M.G.F. da; Silva, O.B. da; Kawashita, K.

    1990-01-01

    Ascertaining the potassium/argon (K/Ar) age of diagenetic illites yields important information for hydrocarbon exploration since the growth of this mineral in the pores of sandstone reservoir and oil migration are interlinked events in the diagenetic evolution of rocks. Illite growth ceases as soon as hydrocarbons completely fill in rock pores, displacing interstitial water. By providing an estimate of the period when the illite formed, K/Ar dating can indirectly tells us when hydrocarbons entered the reservoir. Samples of oil-saturated sandstones collected from Carboniferous reservoirs of the Solimoes Basin reveal a diagenetic evolution consisting predominantly of quartz, calcite, and illite overgrowths. In the present study, illite was mechanically separated by repeating a series of ultrasonic baths and ultrasonic probes followed by high-speed centrifuging. Resultant fractions were analyzed by X-ray diffractometry to measure the illite content of each sample. The separated illite material was found to be composed of illite and ordered mixed layer illite-smectite with 80% illite layers. Separated fractions were dated radiometrically by the K/Ar method. Preliminary results indicate an average age of some 200 m.y., which marks the end of the diagenetic development of the illites of this area. (author)

  1. Comparison of gestational dating methods and implications ...

    Science.gov (United States)

    OBJECTIVES: Estimating gestational age is usually based on date of last menstrual period (LMP) or clinical estimation (CE); both approaches introduce potential bias. Differences in methods of estimation may lead to misclassificat ion and inconsistencies in risk estimates, particularly if exposure assignment is also gestation-dependent. This paper examines a'what-if' scenario in which alternative methods are used and attempts to elucidate how method choice affects observed results.METHODS: We constructed two 20-week gestational age cohorts of pregnancies between 2000 and 2005 (New Jersey, Pennsylvania, Ohio, USA) using live birth certificates : one defined preterm birth (PTB) status using CE and one using LMP. Within these, we estimated risk for 4 categories of preterm birth (PTBs per 106 pregnancies) and risk differences (RD (95% Cl s)) associated with exposure to particulate matter (PM2. 5).RESULTS: More births were classified preterm using LMP (16%) compared with CE (8%). RD divergences increased between cohorts as exposure period approached delivery. Among births between 28 and 31 weeks, week 7 PM2.5 exposure conveyed RDs of 44 (21 to 67) for CE and 50 (18 to 82) for LMP populations, while week 24 exposure conveyed RDs of 33 (11 to 56) and -20 (-50 to 10), respectively.CONCLUSIONS: Different results from analyses restricted to births with both CE and LMP are most likely due to differences in dating methods rather than selection issues. Results are sensitive t

  2. Palaeo-poo: date from rat scats

    International Nuclear Information System (INIS)

    Pearson, S.; Department of Geography.

    1997-01-01

    AMS dating has allowed a detailed study of the stratigraphy of stick-nest rat (Leporillus spp.) middens. The results of multiple dates on apparently the same layers of the middens show that the taphonomy of the midden is complex. Nevertheless, the information recovered from this source is an exciting addition to understanding arid ecosystems. Information about the local and regional vegetation, possible CO 2 -induced changes in stomata, distribution of mammals and their predator-prey relations has been recovered from the middens. Palaeoecological information coming from the arid zone has been limited but this source provides a breakthrough in providing direct and detailed ecological information. This helps contextualise the late Holocene increase in arid zone archaeological site visibility. It emphasises the pattern of arid zone mammal losses. It provides important corroborating evidence to other palaeoecological records. It is emphasised that the deposits containing pollen and macrofossils are datable using radiocarbon but there are some serious problems in providing ecological information from stick-nest rat middens

  3. The Rate of Cyber Dating Abuse among Teens and How It Relates to Other Forms of Teen Dating Violence

    Science.gov (United States)

    Zweig, Janine M.; Dank, Meredith; Yahner, Jennifer; Lachman, Pamela

    2013-01-01

    To date, little research has documented how teens might misuse technology to harass, control, and abuse their dating partners. This study examined the extent of cyber dating abuse--abuse via technology and new media--in youth relationships and how it relates to other forms of teen dating violence. A total of 5,647 youth from ten schools in three…

  4. Dating Norms and Dating Violence among Ninth Graders in Northeast Georgia: Reports from Student Surveys and Focus Groups

    Science.gov (United States)

    Reeves, Patricia M.; Orpinas, Pamela

    2012-01-01

    This mixed-methods study describes the norms supporting male-to-female and female-to-male dating violence in a diverse sample of ninth graders. The quantitative study, based on student surveys (n = 624), compared norms supporting dating violence by sex, race/ethnicity, and dating status, and it examined the relation between dating violence norms…

  5. Dating mortars: three medieval Spanish architectures

    Directory of Open Access Journals (Sweden)

    Quirós Castillo, Juan Antonio

    2011-12-01

    Full Text Available One of the major issues in building archaeology is finding the age of elements and structures discovered. Mortars represent a class of material basically constituted by a mixture of different phases (i.e. binder, aggregates, water and are widely used for constructive uses and artworks. Current scientific literature regarding the possibility of accurate radiocarbon dating for mortars reports different and still contradictory results. In this study, a new protocol for radiocarbon dating of mortar developed at the Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE is used to perform 14C measurements on archaeological mortars coming from three medieval architectures of northern Spain (two churches and the walls of a castle. Results observed will be discussed and compared with independent age estimations (i.e. radiocarbon dating performed on organic materials found in the same study site, archaeological analyses in order to frame experimental observations in the actual site knowledge by means of a multidisciplinary approach.Una de las principales problemáticas a las que se enfrenta la arqueología de la arquitectura es datar los elementos y las estructuras. Las argamasas son un tipo de material constituido por una mezcla de diferentes elementos (agregados, agua y empleadas en muchos tipos de construcciones. Los estudios realizados hasta la actualidad en torno a la posibilidad de realizar dataciones radiocarbónicas precisas han proporcionado resultados contradictorios. El objetivo de este artículo es el de presentar un nuevo protocolo para datar la arquitectura histórica desarrollado por el Centre for Isotopic Research on Cultural and Enviromental Heritage (CIRCE, basado en la realización de dataciones radiocarbónicas de argamasas a partir del análisis de tres arquitecturas medievales del norte del España, dos iglesias y la muralla de un castillo. Los resultados obtenidos han sido confrontados y comparados con otros

  6. Single-grain OSL dating of Early Middle Palaeolithic deposits at Cuesta de la Bajada, Ebro Basin, Spain

    Science.gov (United States)

    Arnold, Lee; Demuro, Martina; Santonja, Manuel; Perez-Gonzalez, Alfredo; Pares, Josep

    2013-04-01

    The open-air site of Cuesta de la Bajada comprises a 2-2.5 m-thick sequence of fluvial-lacustrine sediments inset into the +50-60 m terrace deposits preserved along the south-eastern margins of the Alfambra river valley, Teruel, Spain. The main archaeological horizons lie ~20 m above the present-day river level and consists of an upward-fining sequence of massive fluvial silts and fine sands with dispersed gravels, detritic marls and shales that collectively overlie a series of planar bedded fluvial gravels. These units have yielded ~3000 lithic artefacts displaying reduction techniques characteristic of an early Middle Palaeolithic techno-complex, as well as a multitude of faunal remains indicative of a late Middle Pleistocene origin. The paucity of open-air Palaeolithic sites in the interior eastern sector of the Iberian Peninsula, and the relatively low number of documented early Middle Palaeolithic archives in this region, means that Cuesta de la Bajada is of key importance for understanding the coexistence/transition of Iberian Acheulean and Mousterian techno-complexes during the Middle Pleistocene period. Establishing reliable absolute chronologies at Cuesta de la Bajada remains essential for understanding the regional significance of this site. In an attempt to redress the existing chronological uncertainty we are undertaking an interdisciplinary dating study of the Middle Palaeolithic deposits using OSL dating, ESR/U-series dating of teeth and ESR dating of sedimentary quartz. Here we present results obtained using quartz single-grain OSL dating of 4 samples collected from a 7 m vertical profile bracketing the archaeological horizons. 2 samples were collected from the archaeology-bearing silt and fine sand horizons, while the remaining samples were obtained from well-bedded fine-sands and silts 3.5 m above and 3 m below the main excavation. The measured quartz grains are characterised by relatively bright OSL signals and typically display dose

  7. Obsidian hydration dating of volcanic events

    Science.gov (United States)

    Friedman, I.; Obradovich, J.

    1981-01-01

    Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the 14C and KAr methods at several localities. The localities, ranging in age from 1200 to over 1 million yr, include Newberry Craters, Oregon; Coso Hot Springs, California; Salton Sea, California; Yellowstone National Park, Wyoming; and Mineral Range, Utah. In most cases the agreement is quite good. A number of factors including volcanic glass composition and exposuretemperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure-temperature history requires a number of considerations enumerated in this paper. ?? 1981.

  8. Temporary Immersion System for Date Palm Micropropagation.

    Science.gov (United States)

    Othmani, Ahmed; Bayoudh, Chokri; Sellemi, Amel; Drira, Noureddine

    2017-01-01

    The temporary immersion system (TIS) is being used with tremendous success for automation of micropropagation of many plant species. TIS usually consists of a culture vessel comprising two compartments, an upper one with the plant material and a lower one with the liquid culture medium and an automated air pump. The latter enables contact between all parts of the explants and the liquid medium by setting overpressure to the lower part of the container. These systems are providing the most satisfactory conditions for date palm regeneration via shoot organogenesis and allow a significant increase of multiplication rate (5.5-fold in comparison with that regenerated on agar-solidified medium) and plant material quality, thereby reducing production cost.

  9. AMS radiocarbon dating of ancient Japanese sutras

    CERN Document Server

    Oda, H; Nakamura, T; Fujita, K

    2000-01-01

    Radiocarbon ages of ancient Japanese sutras whose historical ages were known paleographically were measured by means of accelerator mass spectrometry (AMS). Calibrated radiocarbon ages of five samples were consistent with the corresponding historical ages; the 'old wood effect' is negligible for ancient Japanese sutras. Japanese paper has been made from fresh branches grown within a few years and the interval from trimming off the branches to writing sutra on the paper is within one year. The good agreement between the calibrated radiocarbon ages and the historical ages is supported by such characteristics of Japanese paper. It is indicated in this study that Japanese sutra is a suitable sample for radiocarbon dating in the historic period because of little gap by 'old wood effect'.

  10. The automated Risoe TL dating reader system

    International Nuclear Information System (INIS)

    Boetter-Jensen, L.

    1988-01-01

    The features of the new modified Riso TL dating reader system are described. A vacuum chamber that accommodates the entire 24-position sample changer unit has been designed. The vacuum and N 2 -gas functions are software-controlled. A newly designed heater system is capable of repeated heating cycles to 700 0 C. The sample changer system accommodates fine-grain discs as well as planchettes for coarse grains. Two software-controlled beta irradiators can be attached to the reader, e.g. for predose measurement. The software allows a user without programming expertise to create any desired measuring sequence, and to store and recall data and glow curves for making analyses. (author)

  11. AMS radiocarbon dating of ancient Japanese sutras

    International Nuclear Information System (INIS)

    Oda, Hirotaka; Yoshizawa, Yasukazu; Nakamura, Toshio; Fujita, Keiko

    2000-01-01

    Radiocarbon ages of ancient Japanese sutras whose historical ages were known paleographically were measured by means of accelerator mass spectrometry (AMS). Calibrated radiocarbon ages of five samples were consistent with the corresponding historical ages; the 'old wood effect' is negligible for ancient Japanese sutras. Japanese paper has been made from fresh branches grown within a few years and the interval from trimming off the branches to writing sutra on the paper is within one year. The good agreement between the calibrated radiocarbon ages and the historical ages is supported by such characteristics of Japanese paper. It is indicated in this study that Japanese sutra is a suitable sample for radiocarbon dating in the historic period because of little gap by 'old wood effect'

  12. Application of krypton-85 in groundwater dating

    International Nuclear Information System (INIS)

    Rozanski, K.

    1979-01-01

    The method for determination 85 Kr activity in groundwater and its application in isotope hydrology is presented. Various aspects of 85 Kr presence in the earth's ecosphere are discussed in the first part of the paper. The method for 85 Kr activity measurement in groundwater is presented in the second part of the paper. Analytical procedure consists of the following steps: extraction of the gases dissolved in water sample, separation of the Ar+Kr mixture from the gases, 85 Kr activity measurement in miniature proportional counter, mass spectrometry determination of the krypton gas volume in the proportional counter. About 7 days is necessary for complete analysis of one sample - the error of analysis not exceeds 10 per cent. The results of 85 Kr activity measurements (together with tritium and carbon 14 C determinations) in 14 different water samples allowed to verify usefulness of 85 Kr dating of young water. (author)

  13. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    of magnitude and degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants, and animals, shows that age differences of up to 2000 14C years can occur within one river. The freshwater reservoir effect has also implications......The freshwater reservoir effect can result in anomalously old radiocarbon ages of samples from lakes and rivers. This includes the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. Water rich in dissolved ancient calcium carbonates, commonly known...... as hard water, is the most common reason for the freshwater reservoir effect. It is therefore also called hardwater effect. Although it has been known for more than 60 years, it is still less well-recognized by archaeologists than the marine reservoir effect. The aim of this study is to examine the order...

  14. Radiocarbon dating of Irish Sea sediments

    Science.gov (United States)

    Kershaw, P. J.

    1986-09-01

    Radiocarbon dating has been carried out on three cores from areas of muddy sediments in the N. Irish Sea to estimate rates of sediment accumulation. 14C age profiles of the two eastern basin cores revealed a near-constant age from the sediment surface to the base of the core (12 500±1000 years bp). The 14C age profile of the western basin core revealed a zone of apparent mixing to a depth of 55 cm, underlain by a zone of constant sedimentation rate (0·018 cm y -1) to 160 cm. These data are discussed in relation both to previously reported sedimentological studies of the area and to the authorised discharges of low-level radioactive waste from the Sellafield nuclear fuel reprocessing plant.

  15. Dating oxalate minerals in rock surface deposits

    International Nuclear Information System (INIS)

    Watchman, A.

    2001-01-01

    Oxalate minerals are found associated with rocks, mineral coatings, micro-organisms, plants and animals. They are important in archaeology because they have been found intimately associated with organic binders in prehistoric paints. Oxalate minerals also accumulate in the coatings on rock shelter walls and fallen ceiling slabs where they form the natural backing supports for painting and opaque laminates covering engravings. Though the relationship between anthropogenic activity in a rock shelter and oxalate formation is often uncertain, the radiocarbon age of the oxalate may provide the only means for determining the antiquity of a rock painting or engraving. This paper examines the history of dating oxalate minerals at archaeological sites and provides insights into achieving reliable age estimates. (author). 37 refs., 1 fig., 2 tabs

  16. Optimization of laboratory illumination in optical dating

    DEFF Research Database (Denmark)

    Sohbati, Reza; Murray, Andrew; Lindvold, Lars René

    2017-01-01

    As part of the development of new laboratory lighting, we present a methodological approach applicable to the characterization of any light source intended for illumination in optical dating laboratories. We derive optical absorption cross-sections for quartz and feldspar from published data......-emitting diodes (LEDs); this comparison demonstrates the significant advantage of the LED sources over the filtered light sources, because essentially all of the reduction of both OSL and IRSL signals by the LEDs occurs at wavelengths to which the human eye is most sensitive. We conclude that exposure of quartz...... and feldspar extracts from various samples to the light from an LED with emission peak at 594 nm results in a 1% OSL or IRSL signal loss for a 48-h exposure at a power density of ~0.2 mW.cm-2....

  17. Dating methods enter high-school physics curriculum

    International Nuclear Information System (INIS)

    Beck, L.

    2002-01-01

    The new curriculum of physics of the upper forms in French grammar schools includes a part dedicated to ''nuclear transformations''. One of the applications most often considered in manuals is isotopic dating and generally several methods are explained to pupils: carbon 14 dating, potassium-argon dating (used for dating ancient lava layers) and uranium-thorium dating (used for dating corals). The author reviews with a critical eye the content of manuals and laments through concrete examples the lack of exactness and accuracy of some presentations. (A.C.)

  18. Dating by fission tracks in archaeology. 3. Tephrochronology and Hominid dating

    International Nuclear Information System (INIS)

    Poupeau, G.; Zuleta, E.

    1984-01-01

    Tephras (or volcanic ashes) are excellent stratigraphic tracers. Its utilization in this domain, or tephrochronology, is shortly presented. The main archaeological utilization of the tephrochronology is related with the dating of fossil hominids, there where exist the volcano-fossil sedimentar series, at Ceylon or at East-African Rift. (L.C.) [pt

  19. Astronomical dating in the 19th century

    Science.gov (United States)

    Hilgen, Frederik J.

    2010-01-01

    Today astronomical tuning is widely accepted as numerical dating method after having revolutionised the age calibration of the geological archive and time scale over the last decades. However, its origin is not well known and tracing its roots is important especially from a science historic perspective. Astronomical tuning developed in consequence of the astronomical theory of the ice ages and was repeatedly used in the second half of the 19th century before the invention of radio-isotopic dating. Building upon earlier ideas of Joseph Adhémar, James Croll started to formulate his astronomical theory of the ice ages in 1864 according to which precession controlled ice ages occur alternatingly on both hemispheres at times of maximum eccentricity of the Earth's orbit. The publication of these ideas compelled Charles Lyell to revise his Principles of Geology and add Croll's theory, thus providing an alternative to his own geographical cause of the ice ages. Both Croll and Lyell initially tuned the last glacial epoch to the prominent eccentricity maximum 850,000 yr ago. This age was used as starting point by Lyell to calculate an age of 240 million years for the beginning of the Cambrium. But Croll soon revised the tuning to a much younger less prominent eccentricity maximum between 240,000 and 80,000 yr ago. In addition he tuned older glacial deposits of late Miocene and Eocene ages to eccentricity maxima around 800,000 and 2,800,000 yr ago. Archibald and James Geikie were the first to recognize interglacials during the last glacial epoch, as predicted by Croll's theory, and attempted to tune them to precession. Soon after Frank Taylor linked a series of 15 end-moraines left behind by the retreating ice sheet to precession to arrive at a possible age of 300,000 yr for the maximum glaciation. In a classic paper, Axel Blytt (1876) explained the scattered distribution of plant groups in Norway to precession induced alternating rainy and dry periods as recorded by the

  20. Luminescence dating at Rose cottage cave: a progress report

    CSIR Research Space (South Africa)

    Woodborne, S

    1997-10-01

    Full Text Available Deal with infrared-stimulated luminescence and thermoluminescence dates from Rose Cottage Cave in South Africa. Discrepancy between luminescence and radiocarbon dates; Concentration of radioactive elements in sediments before and after leaching...

  1. Functional properties and Solubility of date seed proteins as ...

    African Journals Online (AJOL)

    Med ali

    2013-03-06

    Mar 6, 2013 ... Key words: Phoenix dactylifera L, date palm seed, fibre, protein, functional properties. INTRODUCTION. The date .... was employed to perform dynamic measurements. ... are likely to be composed of high-molecular weight.

  2. 10 CFR 76.43 - Date for decision.

    Science.gov (United States)

    2010-01-01

    ... decision. The Director will render a decision on an application within 6 months of the receipt of the application unless the Director alters the date for decisions and publishes notice of the new date in the...

  3. Combination of archaeomagnetism and thermoluminescence for precision dating

    Science.gov (United States)

    Becker, H.; Göksu, H. Y.; Regulla, D. F.

    Archaeomagnetic dating was applied to two chalk-burning ovens from an early medieval noble-cemetery. Usually this method allows dating by the investigation of the geomagnetic declination and inclination through the thermoremanent magnetisation of baked clay in situ. However, in this case the method resulted in multiple dates since it was not possible to distinguish the brainching of the geomagnetic secular variation curve. Thermoluminescence dating was applied to the same samples to overcome the problem of multiple dates. This first combined application of archaeomagnetism and thermoluminescence for dating yielded A.D. 670±30 for the two ovens, which dates the first stone-church at the site after a wooden predecessor archeologically dated A.D. 620-630.

  4. Development of a new medium containing date syrup for production ...

    African Journals Online (AJOL)

    USER

    2010-08-16

    Aug 16, 2010 ... A confirmatory experiment of the optimal medium composition ... product of date industry; it is rich in carbohydrates (75% w/w) and small ... producers at cheap prices. ... date syrup using a combination of statistical strategies.

  5. Dating of archaeological objects using Carbon-14 facilities

    International Nuclear Information System (INIS)

    Kamisah Hj Alias; Noraishah Othman; Nasasni Nasrol

    2004-01-01

    Dating is the key to organising all archaeological evidence. Furthermore, the development of dating methods, whether traditional or scientific, illustrates the ingenuity and lateral thinking that make archaeological problem-solving such a fascinating exercise. The development of MINT radiocarbon dating procedures is reviewed. Basic principles and counting techniques are discussed. A sample is converted by chemical methods into a suitable form, such as carbon dioxide followed by the acetylene gas, and the benzene end-product is placed inside a proportional counter to measure the radioactivity of 14 C. Not until some years ago did absolute dates by radiocarbon dating become a reality for prehistoric archaeology in Malaysia where thermoluminescence and fission-track dating had begun to provide a locally applicable dating method some decades earlier. Applications of radiocarbon dating procedures in the fields of archaeology are also discussed. (Author)

  6. Constructing deposition chronologies for peat deposits using radiocarbon dating

    Directory of Open Access Journals (Sweden)

    N. Piotrowska

    2011-06-01

    Full Text Available Radiocarbon dating is one of the main methods used to establish peat chronologies. This article reviews the basis of the method and its application to dating of peat deposits. Important steps in the radiocarbon dating procedure are described, including selection and extraction of material (and fractions for dating, chemical and physical preparation of media suitable for measurements, measurements of 14C activity or concentration, calculations, calibration of results and age-depth modelling.

  7. An improved technique for fission track dating

    International Nuclear Information System (INIS)

    Zhao Yunlong; Wu Zhaohui; Xia Yuliang

    1996-01-01

    The necessity of improving the fission track dating (FTD) technique both at home and abroad is illustrated. The ways of making such improvement are also proposed. It is suggested to calibrate the constant b value of the uranium standard glass by using the method of fission products activity. The 3 kinds of uranium standard glass which have been calibrated are NBS SRM962a, UB 1 and UB 2 . An established new method σ·Φ ρ d /b, to measure neutron fluence, avoids the influence of the varying neutron spectrum on measuring neutron fluence. The improved etching technique for fission tracks in zircon adopted a two-step method which includes the molten alkali system etching using NaOH + KOH and the mixed acid system etching using HNO 3 + HF; this technique results in adequate track etching, increased track clarity and less interference. In this way the intensity of tracks is authentically reflected. Dividing angular zone in accordance with the angular distribution of spontaneous fission track on the crystal surface of minerals to count the tracks and using the improved etching technique to remove the non-uniform angular distribution of spontaneous fission tracks in zircon, ensure the accuracy of tracks count. The improved FTD techniques were used to finish Laboratory Standardized Calibration. The tests using international FTD age standards samples have proved that above mentioned techniques are reliable and practical in obtaining the accurate FTD data. (8 tabs.; 3 figs.)

  8. Ages of the solar system: Isotopic dating

    International Nuclear Information System (INIS)

    Turner, G.

    1982-01-01

    The major concern of this section will be to outline the ways in which measurements of isotope abundances have been used to determine the chronology of the origin and evolution of the solar system. In passing it should be remembered that the use of isotopic information is by no means restricted simply to the measurement of time scales and, particularly in recent years, isotope abundances have been used to investigate problems as diverse as the heat sources in the early solar nebula and the chemical evolution of the Earth's mantle. The fundamental property of isotopes which makes them especially useful for dating and other applications is the fact that, apart from a limited amount of mass fractionation, the composition of an isotopic mixture is unaffected by chemical processes. In those cases where mass fractionation does occur this effect may itself be useful, particularly as a source of information on temperatures. Since our main theme is time the events discussed in this section will be most conveniently presented as a chronological sequence, progressing from some time before the solar system existed down to the present day. (orig./WL)

  9. Air pollutants targeted by radiocarbon dating

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    Chemists at the Commerce Department's National Bureau of Standards (NBS) are answering questions about where certain atmospheric contaminants originate by refining a method best known for determining the age of archeological objects. Called radiocarbon dating, the method allows NBS scientists to examine air samples and determine whether contaminants come from naturally occurring or manmade sources-or a combination of the two. Making these distinctions is important to federal and state environmental agencies, which identify industrial sources of pollution for regulatory action. An overbalance of atmospheric carbon can cause a number of environmental problems. In methane's case, high levels are of concern to environmental agencies because of greenhouse properties. Methane also has been implicated as a possible contributor to changes in the ozone layer that protects the Earth from excessive ultraviolet light. Levels of methane have been increasing at an annual rate of about one percent over the last decade. This has caused concern in the environmental community, which hopes to determine just where the elevated levels are coming from. The NBS research is aimed at definitively pinpointing sources of methane and other atmospheric contaminants

  10. Thermoluminescence dating of Brazilian indigenous ceramics

    International Nuclear Information System (INIS)

    Farias, T. M. B.; Gennari, R. F.; Etchevarne, C.; Watanabe, S.

    2009-01-01

    Two indigenous ceramics fragments, one from Lagoa Queimada (LQ) and another from Barra dos Negros (BN), both sites located on Bahia state (Brazil), were dated by thermoluminescence (TL) method. Each fragment was physically prepared and divided into two fractions, one was used for TL measurement and the other for annual dose determination. The TL fraction was chemically treated, divided in sub samples and irradiated with several doses. The plot extrapolation from TL intensities as function of radiation dose enabled the determination of the accumulated dose (D ac ), 3.99 Gy and 1.88 Gy for LQ and BN, respectively. The annual dose was obtained through the uranium, thorium and potassium determination by ICP-MS. The annual doses (D an) obtained were 2.86 and 2.26 mGy/year. The estimated ages were ∼1375 and 709 y for BN and LQ ceramics, respectively. The ages agreed with the archaeologists' estimation for the Aratu and Tupi tradition periods, respectively. (authors)

  11. The dates of publication of Blume’s Flora Javae

    NARCIS (Netherlands)

    Danser, B.H.

    1939-01-01

    The actual dates of publication of the greater part of BLUME’s Flora Javae (lit. 1) appear to be unknown among taxonomists. The title-page of the first volume is dated 1828, and we find the same year at the base of the preface. The volume containing the Orchideae (lit. 2) is dated 1858, but further

  12. Genetic comparisons of Egyptian date palm cultivars (Phoenix ...

    African Journals Online (AJOL)

    Random amplified polymorphic DNA technique was used to compare genetic material from four females date palm and four unknown male trees of Egyptian date palm. The genetic similarity between the four females date palm (Zaghloul, Amhat, Samany and Siwi) ranged from 87.5 to 98.9%. The banding profiles obtained ...

  13. From Romance to Rocket Science: Speed Dating in Higher Education

    Science.gov (United States)

    Muurlink, Olav; Poyatos Matas, Cristina

    2011-01-01

    This article is the first comprehensive review of speed dating in the tertiary sector. While speed dating has its origins as a networking technique to connect singles, it has only more recently made its way into the academy. Since 2005 universities world-wide have begun to adopt speed dating protocols as a tool for building research culture. An…

  14. 24 CFR 232.840 - Date of default.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Date of default. 232.840 Section 232.840 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued....840 Date of default. In computing loan insurance benefits, the date of default shall be considered as...

  15. 24 CFR 241.840 - Date of default.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Date of default. 241.840 Section... § 241.840 Date of default. In computing loan insurance benefits, the date of default shall be considered... of the lender's acceleration of the debt because of the borrower's default under the first...

  16. 17 CFR 230.417 - Date of financial statements.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Date of financial statements... RULES AND REGULATIONS, SECURITIES ACT OF 1933 General Requirements § 230.417 Date of financial statements. Whenever financial statements of any person are required to be furnished as of a date within a...

  17. 75 FR 78155 - Uniform Compliance Date for Food Labeling Regulations

    Science.gov (United States)

    2010-12-15

    .... FDA-2000-N-0011] Uniform Compliance Date for Food Labeling Regulations AGENCY: Food and Drug... 1, 2014, as the uniform compliance date for food labeling regulations that are issued between... established January 2, 2012, as the uniform compliance date for food labeling regulations issued between...

  18. 77 FR 70885 - Uniform Compliance Date for Food Labeling Regulations

    Science.gov (United States)

    2012-11-28

    .... FDA-2000-N-0011] Uniform Compliance Date for Food Labeling Regulations AGENCY: Food and Drug... January 1, 2016, as the uniform compliance date for food labeling regulations that are issued between... established January 1, 2014, as the uniform compliance date for food labeling regulations issued between...

  19. A Survey of Archaeological Samples Dated in 1985

    DEFF Research Database (Denmark)

    Mejdahl, Vagn

    1986-01-01

    A survey is given of archaeological samples received for dating in 1985 at the Nordic Laboratory for Thermoluminescence Dating. A total of 66 samples were dated, 42 of which were burnt stones. All results were corrected for short-term fading as measured for samples stored at room temperature...

  20. A Survey of Archaeological Samples Dated in 1984

    DEFF Research Database (Denmark)

    Mejdahl, Vagn

    A survey is given of archaeological samples dated in 1984 at the Nordic Laboratory for Thermoluminescence Dating. A total of 79 samples were dated, 49 of which were burnt stones. All results were corrected for fading as measured for samples stored for four weeks at room temperature. The alpha dose...

  1. The Role of Perceptions in Dating Violence among Young Adolescents

    Science.gov (United States)

    Prospero, Moises

    2006-01-01

    The high prevalence of dating violence and the severity of its aftermath warrant the collaboration between research and practice for the development of prevention and intervention programs. This study investigates young adolescents' perceptions of dating partner's behaviors in common dating situations and their behavioral reaction to these dating…

  2. A comparison of due-date selection rules

    NARCIS (Netherlands)

    Baker, K.R.; Bertrand, J.W.M.

    1981-01-01

    In sequencing and scheduling models it is usually assumed that due dates represent exogeneous information. In many practical settings, however, due dates can be discretionary, or at least negotiable. Relatively few studies have incorporated discretionary due dates, and even then the rules proposed

  3. 5 CFR 880.206 - Date of death.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Date of death. 880.206 Section 880.206...) RETIREMENT AND INSURANCE BENEFITS DURING PERIODS OF UNEXPLAINED ABSENCE Procedures § 880.206 Date of death... OPM, the date of death of a missing annuitant who has been determined to be dead by an authorized...

  4. 17 CFR 248.18 - Effective date; transition rule.

    Science.gov (United States)

    2010-04-01

    ... Safeguarding Personal Information Relation to Other Laws; Effective Date § 248.18 Effective date; transition... customers on the compliance date. By July 1, 2001, you must have provided an initial notice, as required by § 248.4, to consumers who are your customers on July 1, 2001. (2) Example. You provide an initial notice...

  5. European dendrochronoloy and C-14 dating of timber

    International Nuclear Information System (INIS)

    Fletcher, J.M.

    1975-01-01

    An account is given of the development of dendrochronology and C-14 dating in Europe. Corrections to raw C-14 dates, sampling and the uncertainty of C-14 ages of wood, and correlation of dates obtained by the two methods, are discussed. (U.K.)

  6. Laboratory Intercomparison of Pleistocene Bone Radiocarbon Dating Protocols

    NARCIS (Netherlands)

    Huels, Matthias; van der Plicht, Johannes; Brock, Fiona; Matzerath, Simon; Chivall, David

    2017-01-01

    Since its invention in the late 1940s, radiocarbon (14C) dating has become an important tool for absolute dating. A prerequisite for the acceptance of this method is consistency between, and compatibility of, 14C dates from different laboratories. To meet these requirements, international laboratory

  7. Depressive Symptoms Moderate Dating Violence Prevention Outcomes Among Adolescent Girls.

    Science.gov (United States)

    Collibee, Charlene; Rizzo, Christie J; Kemp, Kathleen; Hood, Erik; Doucette, Hannah; Gittins Stone, Daniel I; DeJesus, Brett

    2018-04-01

    Few dating violence prevention programs assess how variations in initial violence risk affects responsiveness. This study examines the efficacy of Date SMART, a dating violence and sexual risk prevention program designed to target high-risk adolescent girls, in preventing dating violence in the context of varying initial levels of depressive symptoms. A diverse sample of N = 109 female adolescents with a history of physical dating violence participated in a randomized controlled trial of the Date SMART program and a knowledge only (KO) comparison. Using baseline depression level as a primary risk factor, a series of multilevel models revealed significant main effects of baseline depression such that higher baseline depression was associated with greater physical dating violence perpetration and victimization. Results also showed a three-way interaction for assessment point, depressive symptoms, and condition for physical dating violence perpetration. Specifically, those with higher baseline depression in Date SMART showed significantly less physical dating violence perpetration at follow-ups compared with those with higher baseline depression in the KO group. This difference in violence reduction between conditions was not observed for those with lower baseline depression. Date SMART appears to effectively reduce physical dating violence perpetration in those with higher levels of initial risk. Current findings support that adolescents with different risk profiles respond differently to violence prevention programs.

  8. Acculturation and Dating Violence Victimization among Filipino and Samoan Youths

    Science.gov (United States)

    Chung-Do, Jane J.; Goebert, Deborah A.

    2009-01-01

    Dating violence victimization is an important public health issue. Recent studies on minority youths have found higher risks of dating violence victimization compared to White youths. This study examined the influence of acculturation components on youths' experiences of dating violence by utilizing data from a survey of 193 Samoan and Filipino…

  9. Date Fighting and Sexual Risk Behaviours among Adolescents ...

    African Journals Online (AJOL)

    The study seeks to examine the prevalence of date fighting and its role in sexual risk behaviours among 1079 boys and 1211 girls in 22 public secondary schools in Ibadan Nigeria. About 60% (1367) reported to have ever experienced at least a form of date fighting. Risk factors for date fighting in boys include, non use of ...

  10. 16 CFR 700.2 - Date of manufacture.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Date of manufacture. 700.2 Section 700.2... MAGNUSON-MOSS WARRANTY ACT INTERPRETATIONS OF MAGNUSON-MOSS WARRANTY ACT § 700.2 Date of manufacture... after July 4, 1975. When a consumer purchases repair of a consumer product the date of manufacture of...

  11. Dating hapuka otoliths using 210 Pb/226 Ra, with comments on dating orange roughy otoliths

    International Nuclear Information System (INIS)

    Whitehead, N.E.; Ditchburn, R.G.

    1996-01-01

    It is shown that Hapuka otoliths cannot be reliably dated using the 210 Pb/ 226 Ra method because contrary to previous assumptions, excess 210 Pb is incorporated into the outer layers of otoliths which have been taken from old fish, though the 226 Ra incorporation remains normal. This is shown to apply also to Orange Roughy otoliths. Ages based on calculations using previously published methods will be artificially old. (author). 13 refs., 2 tabs., 3 figs

  12. Thermoluminescence dates for the Lake Mungo aboriginal fireplaces and the implications for radiocarbon dating

    International Nuclear Information System (INIS)

    Bell, W.T.

    1991-01-01

    During the Quaternary period in Australia large areas of western New South Wales and northern Victoria were covered by hundreds of lakes, both large and small. Nearly all are dry today but some may still be recognized by the long low dunes that follow the eastern shorelines. Many traces of early human occupation have been found along the shorelines of nearly all the major lakes and some of the best exposures have occurred on the lunette along the eastern shore of Lake Mungo. This lunette, has suffered massive erosion in recent times and this has uncovered the sites of many ancient fireplaces. Charcoal from some of these fireplaces has been dated by Barbetti and Polach (1973) using the radiocarbon method and the ages place the lakeside dwellers at Mungo in an area of Australian prehistory around 30 000 years ago. The baked sediment from below the fireplaces appears to have been heated to a temperature in excess of 400 o C according to archaeomagnetic studies carried out by Barbetti (1973) and this indicated that the fireplaces might lend themselves to the technique of thermoluminescence (TL) dating. The results of the TL dating programme are described elsewhere. (author)

  13. Thermoluminescence dates for the Lake Mungo aboriginal fireplaces and the implications for radiocarbon dating

    Energy Technology Data Exchange (ETDEWEB)

    Bell, W T [Australian National Univ., Canberra (Australia)

    1991-02-01

    During the Quaternary period in Australia large areas of western New South Wales and northern Victoria were covered by hundreds of lakes, both large and small. Nearly all are dry today but some may still be recognized by the long low dunes that follow the eastern shorelines. Many traces of early human occupation have been found along the shorelines of nearly all the major lakes and some of the best exposures have occurred on the lunette along the eastern shore of Lake Mungo. This lunette, has suffered massive erosion in recent times and this has uncovered the sites of many ancient fireplaces. Charcoal from some of these fireplaces has been dated by Barbetti and Polach (1973) using the radiocarbon method and the ages place the lakeside dwellers at Mungo in an area of Australian prehistory around 30 000 years ago. The baked sediment from below the fireplaces appears to have been heated to a temperature in excess of 400{sup o}C according to archaeomagnetic studies carried out by Barbetti (1973) and this indicated that the fireplaces might lend themselves to the technique of thermoluminescence (TL) dating. The results of the TL dating programme are described elsewhere. (author).

  14. Dating sediment cores from Hudson River marshes

    International Nuclear Information System (INIS)

    Robideau, R.; Bopp, R.F.

    1993-01-01

    There are several methods for determining sediment accumulation rates in the Hudson River estuary. One involves the analysis of the concentration of certain radionuclides in sediment core sections. Radionuclides occur in the Hudson River as a result of: natural sources, fallout from nuclear weapons testing and low level aqueous releases from the Indian Point Nuclear Power Facility. The following radionuclides have been studied in the authors work: Cesium-137, which is derived from global fallout that started in the 1950's and has peaked in 1963. Beryllium-7, a natural radionuclide with a 53 day half-life and found associated with very recently deposited sediments. Another useful natural radionuclide is Lead-210 derived from the decay of Radon-222 in the atmosphere. Lead-210 has a half-life of 22 years and can be used to date sediments up to about 100 years old. In the Hudson River, Cobalt-60 is a marker for Indian Point Nuclear Reactor discharges. The author's research involved taking sediment core samples from four sites in the Hudson River Estuarine Research Reserve areas. These core samples were sectioned, dried, ground and analyzed for the presence of radionuclides by the method of gamma-ray spectroscopy. The strength of each current pulse is proportional to the energy level of the gamma ray absorbed. Since different radionuclides produce gamma rays of different energies, several radionuclides can be analyzed simultaneously in each of the samples. The data obtained from this research will be compared to earlier work to obtain a complete chronology of sediment deposition in these Reserve areas of the river. Core samples may then by analyzed for the presence of PCB's, heavy metals and other pollutants such as pesticides to construct a pollution history of the river

  15. Paleomagnetic dating: Methods, MATLAB software, example

    Science.gov (United States)

    Hnatyshin, Danny; Kravchinsky, Vadim A.

    2014-09-01

    A MATLAB software tool has been developed to provide an easy to use graphical interface for the plotting and interpretation of paleomagnetic data. The tool takes either paleomagnetic directions or paleopoles and compares them to a user defined apparent polar wander path or secular variation curve to determine the age of a paleomagnetic sample. Ages can be determined in two ways, either by translating the data onto the reference curve, or by rotating it about a set location (e.g. sampling location). The results are then compiled in data tables which can be exported as an excel file. This data can also be plotted using variety of built-in stereographic projections, which can then be exported as an image file. This software was used to date the giant Sukhoi Log gold deposit in Russia. Sukhoi Log has undergone a complicated history of faulting, folding, metamorphism, and is the vicinity of many granitic bodies. Paleomagnetic analysis of Sukhoi Log allowed for the timing of large scale thermal or chemical events to be determined. Paleomagnetic analysis from gold mineralized black shales was used to define the natural remanent magnetization recorded at Sukhoi Log. The obtained paleomagnetic direction from thermal demagnetization produced a paleopole at 61.3°N, 155.9°E, with the semi-major axis and semi-minor axis of the 95% confidence ellipse being 16.6° and 15.9° respectively. This paleopole is compared to the Siberian apparent polar wander path (APWP) by translating the paleopole to the nearest location on the APWP. This produced an age of 255.2- 31.0+ 32.0Ma and is the youngest well defined age known for Sukhoi Log. We propose that this is the last major stage of activity at Sukhoi Log, and likely had a role in determining the present day state of mineralization seen at the deposit.

  16. Dating the Lascaux cave gour formation

    International Nuclear Information System (INIS)

    Genty, D.; Touma, M.; Konik, S.; Konik, S.; Valladas, H.; Hellstrom, J.; Moreau, C.; Dumoulin, J.P.; Nouet, J.; Dauphin, Y.; Weil, R.

    2011-01-01

    Lascaux Cave is renowned for its outstanding prehistoric paintings, strikingly well-preserved over about 18,000 yr. While stalagmites and stalactites are almost absent in the cave, there is an extensive calcite flow-stone that covered a large part of the cave until its opening for tourists during the 1950's. The deposit comprises a succession of calcite rims, or 'gours', which allowed seepage water to pond in large areas in the cave. Their possible role in preservation of the cave paintings has often been evoked, but until now this deposit has not been studied in detail. Here, we present 24 new radiocarbon accelerator mass spectrometry (AMS) and 6 uranium-thorium (U-Th) analyses from the calcite of the gours, 4 AMS 14 C dates from charcoals trapped in the calcite, and 4 AMS 14 C analyses on organic matter extracted from the calcite. Combining the calibrated 14 C ages obtained on charcoals and organic matter and U-Th ages from 14 C analyses made on the carbonate, has allowed the calculation of the dead carbon proportion (dcp) of the carbonate deposits. The latter, used with the initial atmospheric 14 C activities reconstructed with the new IntCal09 calibration data, allows high-resolution age estimation of the gour calcite samples and their growth rates. The carbonate deposit grew between 9530 and 6635 yr cal BP (for dcp = 10.7 ± 1.8%; 2 s) or between 8518 and 5489 yr cal BP (for dcp = 20.5 ± 1.9%; 2 s). This coincides with humid periods that can be related to the Atlantic period in Europe and to Sapropel 1 in the eastern Mediterranean Sea. However, geomorphological changes at the cave entrance might also have played a role in the gour development. In the 1940's, when humans entered the cave for the first time since its prehistoric occupation, the calcite gours had already been inactive for several thousand years. (authors)

  17. Positives and negatives of online dating according to women 50.

    Science.gov (United States)

    Vandeweerd, Carla; Myers, Jaime; Coulter, Martha; Yalcin, Ali; Corvin, Jaime

    2016-01-01

    To understand the positives and negatives of online dating according to the lived experience of older women, telephone interviews were conducted with 45 women ages 50+ who date online. Interviews were audio recorded, transcribed verbatim, and thematically team coded. The opportunity to expand one's social network for both friendships and romantic partners, the ability to control dating risks and pace of relationship formation, and knowing more about one's partner were significant reported benefits of online dating. Dating online also includes unique risks, such as pervasive lying, attempted financial exploitation in the form of scammers, and unwanted electronic sexual aggression.

  18. Double the dates and go for Bayes - Impacts of model choice, dating density and quality on chronologies

    Science.gov (United States)

    Blaauw, Maarten; Christen, J. Andrés; Bennett, K. D.; Reimer, Paula J.

    2018-05-01

    Reliable chronologies are essential for most Quaternary studies, but little is known about how age-depth model choice, as well as dating density and quality, affect the precision and accuracy of chronologies. A meta-analysis suggests that most existing late-Quaternary studies contain fewer than one date per millennium, and provide millennial-scale precision at best. We use existing and simulated sediment cores to estimate what dating density and quality are required to obtain accurate chronologies at a desired precision. For many sites, a doubling in dating density would significantly improve chronologies and thus their value for reconstructing and interpreting past environmental changes. Commonly used classical age-depth models stop becoming more precise after a minimum dating density is reached, but the precision of Bayesian age-depth models which take advantage of chronological ordering continues to improve with more dates. Our simulations show that classical age-depth models severely underestimate uncertainty and are inaccurate at low dating densities, and also perform poorly at high dating densities. On the other hand, Bayesian age-depth models provide more realistic precision estimates, including at low to average dating densities, and are much more robust against dating scatter and outliers. Indeed, Bayesian age-depth models outperform classical ones at all tested dating densities, qualities and time-scales. We recommend that chronologies should be produced using Bayesian age-depth models taking into account chronological ordering and based on a minimum of 2 dates per millennium.

  19. A Protection Motivation Theory application to date rape education.

    Science.gov (United States)

    Singh, Shweta; Orwat, John; Grossman, Susan

    2011-12-01

    Date rape risk communication is a key component of education-based Date Rape Prevention Programs, common across colleges. In such programs, risk assessment in date rape is approached cautiously in order to avoid a tone of "victim blaming." Since it is important in the assessment of any risk to understand the surrounding social context of the risky situation and the individual's unique relationship with that social context, this study examines Protection Motivation Theory as it applies to handling the risk of date rape without victim blaming. The paper links individual personality and social contexts with risk communication. The study sample comprised 367 undergraduate women enrolled in a large Southern Public University. The study examines the relationships between dating activity, social competency, and type of information provided with the dependents variables of date rape related protection behavior (intent), belief, and knowledge. A factorial multiple analysis of covariance analysis found that the dependent variables had a significant relationship with aspects of social competency and dating activity. The exposure to varying information about date rape was not significantly related to the dependent variables of date rape-related protection behavior (intent), belief, and knowledge. The identification of social competency and dating activity status as protective factors in this study makes a significant contribution to the practice and research efforts in date rape education.

  20. Friends First? The Peer Network Origins of Adolescent Dating

    Science.gov (United States)

    Kreager, Derek A.; Molloy, Lauren E.; Moody, James; Feinberg, Mark E.

    2015-01-01

    The proximity of dating partners in peer friendship networks has important implications for the diffusion of health-risk behaviors and adolescent social development. We derive two competing hypotheses for the friendship-romance association. The first predicts that daters are proximally positioned in friendship networks prior to dating and that opposite-gender friends are likely to transition to dating. The second predicts that dating typically crosses group boundaries and opposite-gender friends are unlikely to later date. We test these hypotheses with longitudinal friendship data for 626 9th grade PROSPER heterosexual dating couples. Results primarily support the second hypothesis: romantic partners are unlikely to be friends in the previous year or share the same cohesive subgroup, and opposite-gender friends are unlikely to transition into dating. PMID:27134511