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Sample records for 206pb 207pb 208pb

  1. Stable (206Pb, 207Pb, 208Pb) and radioactive (210Pb) lead isotopes in 1 year of growth of Sphagnum moss from four ombrotrophic bogs in southern Germany: Geochemical significance and environmental implications

    NASA Astrophysics Data System (ADS)

    Shotyk, William; Kempter, Heike; Krachler, Michael; Zaccone, Claudio

    2015-08-01

    The surfaces of Sphagnum carpets were marked with plastic mesh and 1 year later the production of plant matter was harvested in four ombrotrophic bogs from two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Radioactive, 210Pb was determined in solid samples using ultralow background gamma spectrometry while total Pb concentrations and stable isotopes (206Pb, 207Pb, 208Pb) were determined in acid digests using ICP-SMS. Up to 12 samples (40 × 40 cm) were collected per site, and 6-10 sites investigated per bog. The greatest variations within a given sampling site were in the range 212-532 Bq kg-1 for 210Pb activity, whereas 206Pb/207Pb and 208Pb/206Pb varied less than 1%. The median values of all parameters for the sites (6-10 per bog) were not significantly different. The median activities of 210Pb (Bq kg-1) in the mosses collected from the bogs in NBF (HO = 372 ± 56, n = 55; WI = 342 ± 58, n = 93) were slightly less from those in OB (GS = 394 ± 50, n = 55; KL = 425 ± 58, n = 24). However, the mosses in the NBF bogs exhibited much greater productivity (187-202 g m-2 a-1) compared to those of OB (71-91 g m-2 a-1), and this has a profound impact on the accumulation rates of 210Pb (Bq m-2 a-1), with the bogs in the NBF yielding fluxes (HO = 73 ± 30; WI = 65 ± 20) which are twice those of OB (GS = 29 ± 11; KL = 40 ± 13). Using the air concentrations of 210Pb measured at Schauinsland (SIL) in the southern Black Forest and average annual precipitation, the atmospheric fluxes of 210Pb at SIL (340 Bq m-2 a-1) exceeds the corresponding values obtained from the mosses by a factor of five, providing the first quantitative estimate of the net retention efficiency of 210Pb by Sphagnum. When the 210Pb activities of all moss samples are combined (n = 227), a significant decrease with increasing plant production rate is observed; in contrast, total Pb concentrations show the opposite trend. The contrasting

  2. Characterization of the ground X{sub 1} state of {sup 204}Pb{sup 19}F, {sup 206}Pb{sup 19}F, {sup 207}Pb{sup 19}F, and {sup 208}Pb{sup 19}F

    SciTech Connect

    Mawhorter, Richard J.; Murphy, Benjamin S.; Baum, Alexander L.; Sears, Trevor J.; Yang, T.; Rupasinghe, P. M; McRaven, C. P.; Shafer-Ray, N. E.; Alphei, Lukas D.; Grabow, Jens-Uwe

    2011-08-15

    Pure rotational spectra of the ground electronic-vibrational X{sub 1} state of {sup 204}Pb{sup 19}F, {sup 206}Pb{sup 19}F, {sup 207}Pb{sup 19}F, and {sup 208}Pb{sup 19}F are measured with a resonator pulsed supersonic jet Fourier-transform microwave spectrometer. Also reported is a new measurement of the Stark effect on the optical spectra of A(leftarrow)X{sub 1} transitions. These spectra are combined with published high-resolution infrared spectra of X{sub 2}{r_reversible}X{sub 1} transitions in order to create a complete picture of the ground state of lead monofluoride. For the microwave data, molecules are prepared by laser ablation of lead target rods and stabilized in a supersonic jet of neon mixed with sulfur hexafluoride. For the optical Stark spectra, a continuous source of molecules is created in a nozzle heated to 1000 deg. C. The microwave spectra confirm, improve, and extend previously reported constants that describe the rotational, spin-orbit, and hyperfine interactions of the ground electronic state of the PbF molecule. A discrepancy concerning the sign of the hyperfine constant describing the {sup 207}Pb nucleus is discussed. Magnetic-field-dependent microwave spectra are used to characterize the Zeeman interaction in terms of two g factors of the body-fixed electronic wave function. The optical Stark spectra are used to characterize the electric dipole moment of the X{sub 1} and A states.

  3. European isotopic signatures for lead in atmospheric aerosols: a source apportionment based upon 206Pb/207Pb ratios.

    PubMed

    Flament, Pascal; Bertho, Marie-Laure; Deboudt, Karine; Véron, Alain; Puskaric, Emile

    2002-09-16

    To investigate the capability of the lead isotope signature technique to support a source apportionment study at a Continental scale, atmospheric particulate matter was collected at Cap Gris-Nez (Eastern Channel, northern France), over one year (1995-1996). Four days retrospective trajectories of air masses were available during each sampling experiment. Twenty-eight samples, for which the origin of aerosols was unambiguously determined, were selected for isotopic measurements. Considering the Enrichment Factors, EF(Crust) of lead and its size distribution, we show that lead is mostly from anthropogenic origin and mainly associated with [0.4 < diameter < 0.9 microm] particles. The extent to which various Continental sources influence the lead abundance in aerosols is exhibited by considering both the lead concentration and the origin of air masses. Lead concentration is higher by a factor of approximately seven, when air masses are derived from Continental Europe, by comparison with marine air masses. Taking into account these concentrations and the vertical movements of air masses, we compare the different isotopic compositions using a statistical non-parametric test (Kolmogorov-Smirnov). We produce evidence that, for most of the cases, air masses originating from Continental Europe exhibit a more radiogenic composition (1.134 < 206Pb/207Pb < 1.172) than air masses coming from the United Kingdom (1.106 < 206Pb/207Pb < 1.124). Generally, lead isotopic compositions in aerosols are clearly distinct from the gasoline signatures in European countries, strongly suggesting that automotive lead is no longer the major component of this metal in the air. Gasoline and industrial isotopic signatures could explain the origin of lead in our aerosol samples. A source apportionment based upon 206Pb/207Pb ratios, suggests that the difference between British (206Pb/207Pb = 1.122 +/- 0.038) and Continental (206Pb/207Pb = 1.155 +/- 0.022) signatures may be largely explained by

  4. 207Pb(n,2n{gamma})206Pb Cross-Section Measurements by In-Beam Gamma-Ray Spectroscopy

    SciTech Connect

    Baumann, P.; Kerveno, M.; Rudolf, G.; Borcea, C.; Jericha, E.; Jokic, S.; Lukic, S.; Mihailescu, L. C.; Plompen, A. J. M.; Pavlik, A.

    2006-03-13

    207Pb(n,2n{gamma})206Pb cross section were measured for incident neutron energies between 6 and 20 MeV with the white neutron beam produced at GELINA. The {gamma}-ray production cross section for the main transition (803 keV, 2+{yields} 0+) in 206Pb is compared to results obtained at Los Alamos and to the TALYS and EMPIRE-II code predictions.

  5. New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei

    SciTech Connect

    Broda, R.; Wrzesinski, J.; Pawlat, T.

    1996-12-31

    The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.

  6. The changing nature of the 206Pb/207Pb isotopic ratio of lead in rainwater, atmospheric particulates, pine needles and leaded petrol in Scotland, 1982-1998.

    PubMed

    Farmer, J G; Eades, L J; Graham, M C; Bacon, J R

    2000-02-01

    The inductively coupled plasma-mass spectrometry (ICP-MS)-determined 206Pb/207Pb ratio of 145 samples of rainwater collected at 25 locations around Scotland during December 1997 and January 1998 and at three longterm monitoring stations in the northeast, central belt and southeast of the country from November 1997 to December 1998 averaged 1.144+/-0.017 (1 s). This represents a significant increase from the mean value of 1.120+/-0.016 recorded for the long-term sites in 1989 1991, only partly attributable to a concomitant increase in the 206Pb/207Pb ratio of leaded petrol from 1.075+/-0.013 to 1.088+/-0.007. The rainwater 206Pb/207Pb data for the late 1990s also contrast markedly with the lower 206Pb/207Pb ratios found for pine needle and atmospheric particulate samples from Scotland (e.g. Glasgow: 1.085+/-0.012 in 1985-1986, 1.099+/-0.007 in 1991-1992), England and Western Europe in this study for the period 1982-1992 when emissions of lead to the atmosphere from petrol-engined vehicles in the UK were approximately 2-9 times higher. The observed change in the lead isotopic signature of rainwater predominantly reflects the impact of measures, such as the introduction and growing uptake of unleaded petrol, to reduce car exhaust emissions of lead to the atmosphere in the UK. Based on the rainwater data, source apportionment calculations suggest a general decline in the contribution of leaded petrol to atmospheric lead in Scotland from 53-61% in 1989-1991 to 32-45% in 1997-1998, with a corresponding decline in the urban environment from 84-86% to 48-58%.

  7. Tree rings as Pb pollution archives? A comparison of 206Pb/207Pb isotope ratios in pine and other environmental media.

    PubMed

    Bindler, Richard; Renberg, Ingemar; Klaminder, Jonatan; Emteryd, Ove

    2004-02-05

    Tree rings, if validated as an environmental archive for pollution, would provide a convenient, geographically widespread archive for studying the temporal and spatial distribution of atmospheric pollutants. We collected tree-ring records from Scots pine (Pinus sylvestris L.), ranging in age from 100 to 300 years and from one spruce (Picea abies), from sites in southern and northern Sweden and analyzed their stable lead isotopic composition (206Pb/207Pb). These results are compared to the Pb isotopic composition in soil profiles from each of the sites and temporal changes in the 206Pb/207Pb ratio in peat and lake sediment deposits in Sweden. The mineral soils at each site are characterized by high 206Pb/207Pb ratios (> 1.35), while the ratios in the mor layer are low (1.14-1.16) and characterized by atmospheric lead pollution. The 206Pb/207Pb ratios of the tree rings, typically approximately 1.18-1.20, indicate a significant (10-30%) contribution of Pb derived from the underlying mineral soil. While peat and lake sediment records show that the 206Pb/207Pb ratio of atmospheric deposition has varied over time, with a pronounced trough between approximately 1930 and 1990, the tree rings show no similar trend. Further comparison of published Pb isotope data from other tree-ring records with time series from peat bogs and herbarium samples also shows poor agreement, and indicates that tree rings always contain a mixture of pollution Pb and Pb from the underlying mineral soil. The majority of Pb in the wood is derived from atmospheric pollution either directly, through aerial interception, or indirectly, through uptake from the large pool of accumulated pollution Pb in the soil. Since the Pb isotope ratios of the wood indicate that some natural Pb is taken up into the tree, then it must also be concluded that some fraction of the pollution Pb in the wood is likewise taken up from the forest soil. Based on the Pb isotope analyses, we can only conclude that dendrochemical

  8. Lead fluxes and 206Pb/207Pb isotope ratios in rime and snow collected at remote mountain-top locations (Czech Republic, Central Europe): Patterns and sources

    NASA Astrophysics Data System (ADS)

    Cimova, Nikoleta; Novak, Martin; Chrastny, Vladislav; Curik, Jan; Veselovsky, Frantisek; Blaha, Vladimir; Prechova, Eva; Pasava, Jan; Houskova, Marie; Bohdalkova, Leona; Stepanova, Marketa; Mikova, Jitka; Krachler, Michael; Komarek, Arnost

    2016-10-01

    During three winter seasons (2009-2011), Pb concentrations were measured in precipitation at 10 high-elevation sites in the Czech Republic, close to the borders with Austria, Germany, Poland, and Slovakia. Soluble and insoluble Pb forms were quantified in snow (vertical deposition), and rime (horizontal deposition). The objective was to compare Pb input fluxes into ecosystems via vertical and horizontal deposition, and to identify the residual Pb pollution sources in an era of rapidly decreasing industrial pollution. Lead soluble in diluted HNO3 made up 96% of total Pb deposition, with the remaining 4% Pb bound mainly in silicates. Three times higher concentrations of soluble Pb in rime than in snow, and 2.5 times higher concentrations of insoluble Pb in rime than in snow were associated with slightly different Pb isotope ratios. On average, the 206Pb/207Pb ratios in rime were higher than those in snow. Higher mean 206Pb/207Pb ratios of insoluble Pb (1.175) than in soluble Pb (1.165) may indicate an increasing role of geogenic Pb in recent atmospheric deposition. A distinct reversal to more radiogenic 206Pb/207Pb ratios in snow and rime in 2010, compared to literature data from rain-fed Sphagnum peatlands (1800-2000 A.D.), documented a recent decrease in anthropogenic Pb in the atmosphere of Central Europe. Since the early 1980s, Pb concentrations in snow decreased 18 times in the rural south of the Czech Republic, but only twice in the industrial north of the Czech Republic. Isotope signatures indicated that Pb in today's atmospheric deposition is mainly derived from Mesozoic ores mined/processed in Poland and coal combustion in the Czech Republic and Poland.

  9. Threshold photoneutron cross sections for {sup 208,207,206}Pb isotopes

    SciTech Connect

    Kondo, T.; Utsunomiya, H.; Akimune, H.; Yamagata, T.; Iwamoto, C.; Kamata, M.; Itoh, O.; Toyokawa, H.; Lui, Y.-W.

    2010-06-01

    Photoneutron cross sections for three Pb isotopes ({sup 206}Pb, {sup 207}Pb, {sup 208}Pb) near neutron threshold were measured with the laser inverse-Compton scattering gamma rays at the National Institute of Advanced Industrial Science and Technology. The cross section data are presented.

  10. 206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal, Yucca Mountain, Nevada

    USGS Publications Warehouse

    Neymark, Leonid A.; Amelin, Yuri V.; Paces, James B.

    2000-01-01

    U–Th–Pb isotopic systems have been studied in submillimeter-thick outermost layers of Quaternary opal occurring in calcite–silica fracture and cavity coatings within Tertiary tuffs at Yucca Mountain, Nevada, USA. These coatings preserve a record of paleohydrologic conditions at this site, which is being evaluated as a potential high-level nuclear waste repository. The opal precipitated from groundwater is variably enriched in 234U (measured 234U/238U activity ratio 1.124–6.179) and has high U (30–313 ppm), low Th (0.008–3.7 ppm), and low common Pb concentrations (measured 206Pb/204Pb up to 11,370). It has been demonstrated that the laboratory acid treatment used in this study to clean sample surfaces and to remove adherent calcite, did not disturb U–Th–Pb isotopic systems in opal. The opal ages calculated from 206Pb∗/238U and 207Pb∗/235U ratios display strong reverse discordance because of excess radiogenic 206Pb∗ derived from the elevated initial 234U. The data are best interpreted using projections of a new four-dimensional concordia diagram defined by 206Pb∗/238U, 207Pb∗/235U, 234U/238Uactivity, and 230Th/238Uactivity. Ages and initial 234U/238U activity ratios have been calculated using different projections of this diagram and tested for concordance. The data are discordant, that is observed 207Pb∗/235U ages of 170 ± 32 (2σ) to 1772 ± 40 ka are systematically older than 230Th/U ages of 34.1 ± 0.6 to 452 ± 32 ka. The age discordance is not a result of migration of uranium and its decay products under the open system conditions, but a consequence of noninstantaneous growth of opal. Combined U–Pb and 230Th/U ages support the model of slow mineral deposition at the rates of millimeters per million years resulting in layering on a scale too fine for mechanical sampling. In this case, U–Pb ages provide more accurate estimates of the average age for mixed multiage samples than 230Th/U ages, because ages based on shorter

  11. Ground state partial radiative widths of /sup 207/Pb + n resonances and M1 and E2 strengths in /sup 208/Pb

    SciTech Connect

    Weigmann, H.; Koehler, R.; Poortmans, F.; Raman, S.; Wartena, J.A.

    1987-08-01

    Ground state partial radiative widths of neutron resonances in /sup 207/Pb + n have been measured. A resonance analysis has been carried out in a complete manner below 700 keV neutron energy, and for selected strongly radiation resonances up to 1 MeV. The total magnetic dipole strength detected above neutron separation energy is only 6.8 ..mu../sub 0//sup 2/, but the observed appreciable fragmentation of the M1 strength suggests that considerable strength is missed at excitation energies above 8 MeV. The electric quadrupole strength observed between neutron separation energy and 8.2 MeV is distributed rather uniformly, and corresponds to 4.9% of the energy-weighted sum-rule for isoscalar E2 transitions. 10 refs., 2 figs.

  12. Geochemistry and 207Pb/ 206Pb zircon ages of granitoids from the southern portion of the Tamboril-Santa Quitéria granitic-migmatitic complex, Ceará Central Domain, Borborema Province (NE Brazil)

    NASA Astrophysics Data System (ADS)

    de Araujo, Carlos E. G.; Costa, Felipe G.; Pinéo, Tercyo R. G.; Cavalcante, José C.; Moura, Candido A. V.

    2012-02-01

    The Tamboril-Santa Quitéria Complex is an important Neoproterozoic granitic-migmatitic unit from the Ceará Central Domain that developed from ca. 650 to 610 Ma. In general the granitoids range in composition from diorite to granite with predominance (up to 85%) of granitic to monzogranitic composition with biotite as the main mafic AFM phase. Geochemical and 207Pb/ 206Pb evaporation zircon geochronology studies were applied in a group of these abundant monzogranitic rocks from the region of Novo Oriente in the southern portion of the Ceará Central Domain. In this area the granitoids are weakly peraluminous biotite granitoids and deformed biotite granitoids of high-K calc-alkaline and ferroan composition, which we interpreted as primary magmas (segregated diatexites) derived from the partial melting of crustal material. The close temporal relation of this magmatism with local eclogitic and regional high temperature metamorphism in Ceará Central Domain point out to an orogenic setting, arguably emplaced during the collisional stage. Subordinate coeval juvenile mantle incursions are also present. This crustally derived magmatism is the primary product of the continental thickening that resulted from the collision between the rocks represented by the Amazonian-West African craton (São Luiz cratonic fragment) to the northwest and the Paleoproterozoic-Archean basement of the Borborema Province to the southeast along the Transbrasiliano tectonic corridor.

  13. Comment on "207Pb-206Pb single-zircon evaporation ages of some granitoid rocks reveal continent-oceanic island arc collision during the Cretaceous geodynamic evolution of the Central Anatolian crust, Turkey" - Boztug, D., Tichomirowa, M. & Bombach, K., 2007, JAES 31, 71-86

    NASA Astrophysics Data System (ADS)

    Göncüoglu, M. Cemal

    A continent-oceanic island arc collision model was proposed as a new geodynamic scenario for the evolution of the Cretaceous Central Anatolian granitoids in the Central Anatolian crystalline complex (CACC) by Boztug et al. (2007b) [Boztug, D., Tichomirowa, M., Bombach, K., 2007b. 207Pb-206Pb single-zircon evaporation ages of some granitoid rocks reveal continent-oceanic island arc collision during the Cretaceous geodynamic evolution of the central Anatolian crust, Turkey. Journal of Asian Earth Sciences 31, 71-86]. The key aspects of this model include an intra-oceanic subduction in the Neotethyan Izmir-Ankara Ocean, formation of an island arc and its subsequent collision with the northern margin of the Tauride-Anatolide Platform. The identical scenario was initially proposed by Göncüoglu et al. (1992) [Göncüoglu, M.C., Erler, A., Toprak, V., Yalınız, K., Olgun, E., Rojay, B., 1992. Geology of the western Central Anatolian Massif, Part II: Central Areas. TPAO Report No: 3155, 76 p] . Moreover, the weighted mean values of the reported 207Pb-206Pb single-zircon evaporation ages by Boztug et al. (2007b) [Boztug, D., Tichomirowa, M., Bombach, K., 2007b. 207Pb-206Pb single-zircon evaporation ages of some granitoid rocks reveal continent-oceanic island arc collision during the Cretaceous geodynamic evolution of the central Anatolian crust: Turkey. Journal of Asian Earth Sciences 31, 71-86] from A-type granitoids in the CACC seem to be miscalculated and contrast with the field data.

  14. Search for the two-phonon octupole vibrational state in {sup 208}Pb

    SciTech Connect

    Blumenthal, D.J.; Henning, W.; Janssens, R.V.F.

    1995-08-01

    We performed an experiment to search for the two-phonon octupole vibrational state in {sup 208}Pb. Thick targets of {sup 208}Pb, {sup 209}Bi, {sup 58,64}Ni, and {sup 160}Gd were bombarded with 1305 MeV beams of were bombard {sup 208}Pb supplied by ATLAS. Gamma rays were detected using the Argonne-Notre Dame BGO gamma-ray facility, consisting of 12 Compton-suppressed germanium detectors surrounding an array of 50 BGO scintillators. We identified some 30 known gamma rays from {sup 208}Pb in the spectra gated by the 5{sup -} {yields} 3{sup -} and 3{sup -} {yields} 0{sup +} transitions in {sup 208}Pb. In addition, after unfolding these spectra for Compton response, we observed broad coincident structures in the energy region expected for the 2-phonon states. Furthermore, we confirmed the placement of a 2485 keV line observed previously in {sup 207}Pb and find no evidence consistent with the placement of this line in {sup 208}Pb. We are currently in the process of investigating the origin of the broadened lines observed in the spectra, extracting the excitation probability of states in {sup 208}Pb, and determining the relative probability of mutual excitation and neutron transfer in this reaction. An additional experiment is also being performed to collect much higher statistics germanium-germanium coincidence data for the thick {sup 208}Pb target.

  15. Interaction of 11Li with 208Pb

    NASA Astrophysics Data System (ADS)

    Vinodkumar, A. M.; Loveland, W.; Yanez, R.; Leonard, M.; Yao, L.; Bricault, P.; Dombsky, M.; Kunz, P.; Lassen, J.; Morton, A. C.; Ottewell, D.; Preddy, D.; Trinczek, M.

    2013-04-01

    Background: 11Li is one of the most studied halo nuclei. The fusion of 11Li with 208Pb is the subject of a number of theoretical studies with widely differing predictions, ranging over four orders of magnitude, for the fusion excitation function.Purpose: The purpose was to measure the excitation function for the 11Li + 208Pb reaction.Methods: A stacked foil and degrader assembly of 208Pb targets was irradiated with a 11Li beam producing center-of-target beam energies from above-barrier to near-barrier energies (40-29 MeV). The intensity of the 11Li beam (chopped) was 1250 particles/s and the beam on-target time was 34 h. The α decay of the stopped evaporation residues (EVRs) was detected in an α-detector array at each beam energy in the beam-off period (the beam was on for ≤5 ns and then off for 170 ns).Results: The observed nuclidic yields of 212/215At and 214At are consistent with being produced in the complete fusion of 11Li with 208Pb. The observed yields of 213At appear to be the result of the breakup of 11Li into 9Li+2n, with the 9Li fusing with 208Pb. The magnitudes of the total fusion cross sections are substantially less than most theoretical predictions.Conclusions: It is possible to measure the EVR production cross sections resulting from the interaction of 11Li with 208Pb using current-generation radioactive beam facilities. Both complete fusion and breakup fusion processes occur in the interaction of 11Li with 208Pb. An important breakup process leads to the fusion of the 9Li fragment with 208Pb.

  16. Deep Sub-Barrier Fusion Enhancement in the {sup 6}He+{sup 206}Pb Reaction

    SciTech Connect

    Penionzhkevich, Yu.E.; Zagrebaev, V.I.; Lukyanov, S.M.; Kalpakchieva, R.

    2006-04-28

    The fusion of {sup 6}He with {sup 206}Pb has been studied at energies close to and below the Coulomb barrier. The experiment was carried out at the Dubna Radioactive Ion Beams complex of FLNR, JINR. The {sup 6}He beam intensity was about 5x10{sup 6} pps, the maximum energy being 60.3{+-}0.4 MeV. The yield of the {sup 210}Po isotope, produced in the 2n-evaporation channel, demonstrates an extremely large enhancement of the sub-barrier fusion cross section as compared with the {sup 4}He+{sup 208}Pb reaction. This enhancement is most likely due to the mechanism of 'sequential fusion' with an intermediate neutron transfer from {sup 6}He to the Pb nucleus with positive Q values.

  17. Particle Production in 158.A GeV 208Pb+208Pb Collisions

    SciTech Connect

    Awes, T.C.

    1999-01-09

    The production of neutral pions in 158A GeV {sup 208}Pb+{sup 208}Pb collisions has been studied in the WA98 experiment. The centrality dependence of the neutral pion production is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with more than about 50 participants. The transverse mass spectrum is analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement constrains the extracted freeze-out parameters, and provides information on the freeze-out velocity profile.

  18. Using stable lead isotopes to trace heavy metal contamination sources in sediments of Xiangjiang and Lishui Rivers in China.

    PubMed

    Sun, Guo-Xin; Wang, Xin-Jun; Hu, Qin-Hong

    2011-12-01

    Lead isotopes and heavy metal concentrations were measured in two sediment cores sampled in estuaries of Xiangjiang and Lishui Rivers in Hunan province, China. The presence of anthropogenic contribution was observed in both sediments, especially in Xiangjiang sediment. In the Xiangjiang sediment, the lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratio, than natural Pb isotope signature (1.198 and 2.075 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively), indicated a significant input of non-indigenous Pb with low (206)Pb/(207)Pb and high (208)Pb/(206)Pb. The corresponding concentrations of heavy metals (As, Cd, Zn, Mn and Pb) were much higher than natural values, suggesting the contaminations of heavy metals from extensive ore-mining activities in the region.

  19. Feather lead concentrations and207Pb/206Pb ratios reveal lead exposure history of California condors (Gymnogyps californianus)

    USGS Publications Warehouse

    Finkelstein, M.E.; George, D.; Scherbinski, S.; Gwiazda, R.; Johnson, M.; Burnett, J.; Brandt, J.; Lawrey, S.; Pessier, Allan P.; Clark, M.; Wynne, J.; Grantham, And J.; Smith, D.R.

    2010-01-01

    Lead poisoning is a primary factor impeding the survival and recovery of the critically endangered California Condor (Gymnogyps californianus). However, the frequency and magnitude of lead exposure in condors is not well-known in part because most blood lead monitoring occurs biannually, and biannual blood samples capture only ???10% of a bird's annual exposure history. We investigated the use of growing feathers from free-flying condors in California to establish a bird's lead exposure history. We show that lead concentration and stable lead isotopic composition analyses of sequential feather sections and concurrently collected blood samples provided a comprehensive history of lead exposure over the 2-4 month period of feather growth. Feather analyses identified exposure events not evident from blood monitoring efforts, and by fitting an empirically derived timeline to actively growing feathers, we were able to estimate the time frame for specific lead exposure events. Our results demonstrate the utility of using sequentially sampled feathers to reconstruct lead exposure history. Since exposure risk in individuals is one determinant ?? 2010 American Chemical Society.

  20. Feather lead concentrations and (207)Pb/(206)Pb ratios reveal lead exposure history of California Condors (Gymnogyps californianus).

    PubMed

    Finkelstein, M E; George, D; Scherbinski, S; Gwiazda, R; Johnson, M; Burnett, J; Brandt, J; Lawrey, S; Pessier, A P; Clark, M; Wynne, J; Grantham, J; Smith, D R

    2010-04-01

    Lead poisoning is a primary factor impeding the survival and recovery of the critically endangered California Condor (Gymnogyps californianus). However, the frequency and magnitude of lead exposure in condors is not well-known in part because most blood lead monitoring occurs biannually, and biannual blood samples capture only approximately 10% of a bird's annual exposure history. We investigated the use of growing feathers from free-flying condors in California to establish a bird's lead exposure history. We show that lead concentration and stable lead isotopic composition analyses of sequential feather sections and concurrently collected blood samples provided a comprehensive history of lead exposure over the 2-4 month period of feather growth. Feather analyses identified exposure events not evident from blood monitoring efforts, and by fitting an empirically derived timeline to actively growing feathers, we were able to estimate the time frame for specific lead exposure events. Our results demonstrate the utility of using sequentially sampled feathers to reconstruct lead exposure history. Since exposure risk in individuals is one determinant of population health, our findings should increase the understanding of population-level effects from lead poisoning in condors; this information may also be helpful for other avian species potentially impacted by lead poisoning.

  1. Parity nonconservation in {sup 207}Pb

    SciTech Connect

    Leuschner, M.; Cain, B.; Knott, J.E.; Komives, A.; Szymanski, J.J.; Andalkar, A.; Girit, I.C.; Petrov, M.; Bowman, J.D.

    1995-07-10

    Two experiments are currently underway to measure the single-particle weak mixing matrix element for the 1064 KeV transition in {sup 207}Pb. One experiment measures the circular polarization of the 1064 KeV gamma ray emitted from an unpolarized source, while the other experiment measures the forward-backward asymmetry of gamma rays emitted from a polarized source. Analysis of the first set of polarized source data yields an upper limit of 46 eV for the single-particle weak mixing matrix element. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  2. Partial Photoneutron Cross Sections for 207,208Pb

    NASA Astrophysics Data System (ADS)

    Kondo, T.; Utsunomiya, H.; Goriely, S.; Iwamoto, C.; Akimune, H.; Yamagata, T.; Toyokawa, H.; Harada, H.; Kitatani, F.; Lui, Y.-W.; Hilaire, S.; Koning, A. J.

    2014-05-01

    Using linearly-polarized laser-Compton scattering γ-rays, partial E1 and M1 photoneutron cross sections along with total cross sections were determined for 207,208Pb at four energies near neutron threshold by measuring anisotropies in photoneutron emission. Separately, total photoneutron cross sections were measured for 207,208Pb with a high-efficiency 4π neutron detector. The partial cross section measurement provides direct evidence for the presence of pygmy dipole resonance (PDR) in 207,208Pb in the vicinity of neutron threshold. The strength of PDR amounts to 0.32%-0.42% of the Thomas-Reiche-Kuhn sum rule. Several μN2 units of B(M1)↑ strength were observed in 207,208Pb just above neutron threshold, which correspond to M1 cross sections less than 10% of the total photoneutron cross sections.

  3. Identifying sources of Pb pollution in urban soils by means of MC-ICP-MS and TOF-SIMS.

    PubMed

    Rodríguez-Seijo, Andrés; Arenas-Lago, Daniel; Andrade, María Luisa; Vega, Flora A

    2015-05-01

    Lead pollution was evaluated in 17 urban soils from parks and gardens in the city of Vigo (NW Spain). The Pb isotope ratios ((207)Pb/(206)Pb, (208)Pb/(204)Pb, (206)Pb/(204)Pb and (208)Pb/(206)Pb) were determined after being measured by MC-ICP-MS. The association of the isotopes ((204)Pb, (206)Pb, (207)Pb and (208)Pb) with the different components of the soil was studied using TOF-SIMS. The isotopic ranges obtained for the samples were between 1.116 and 1.203 ((206)Pb/(207)Pb), 2.044-2.143 ((208)Pb/(206)Pb), 37.206-38.608 ((208)Pb/(204)Pb), 15.5482-15.6569 ((207)Pb/(204)Pb) and 17.357-18.826 ((206)Pb/(204)Pb). The application of the three-end-member model indicates that the Pb derived from petrol is the main source of Pb in the soils (43.51% on average), followed by natural or geogenic Pb (39.12%) and industrial emissions (17.37%). The emissions derived from coal combustion do not appear to influence the content of Pb in the soil. TOF-SIMS images show that the Pb mainly interacts with organic matter. This technique contributes to the understanding of the association of anthropogenic Pb with the components of the soil, as well as the particle size of these associations, thus allowing the possible sources of Pb to be identified.

  4. Identification of the sources of metal (lead) contamination in drinking waters in north-eastern Tasmania using lead isotopic compositions.

    PubMed

    Harvey, P J; Handley, H K; Taylor, M P

    2015-08-01

    This study utilises a range of scientific approaches, including lead isotopic compositions, to differentiate unknown sources of ongoing lead contamination of a drinking water supply in north-eastern Tasmania, Australia. Drinking water lead concentrations are elevated above the Australian Drinking Water Guideline (10 μg/L), reaching 540 μg/L in the supply network. Water lead isotopic compositions from the town of Pioneer ((208)Pb/(207)Pb 2.406, (206)Pb/(207)Pb 1.144 to (208)Pb/(207)Pb 2.360, (206)Pb/(207)Pb 1.094) and Ringarooma ((208)Pb/(207)Pb 2.398, (206)Pb/(207)Pb 1.117) are markedly different from the local bedrock ((208)Pb/(207)Pb 2.496, (206)Pb/(207)Pb 1.237). The data show that the lead in the local waters is sourced from a combination of dilapidated drinking water infrastructure, including lead jointed pipelines, end-of-life polyvinyl chloride pipes and household plumbing. Drinking water is being inadvertently contaminated by aging infrastructure, and it is an issue that warrants investigation to limit the burden of disease from lead exposure.

  5. Fusion of {sup 9}Li with {sup 208}Pb

    SciTech Connect

    Vinodkumar, A. M.; Loveland, W.; Sprunger, P. H.; Prisbrey, L.; Trinczek, M.; Dombsky, M.; Machule, P.; Kolata, J. J.; Roberts, A.

    2009-11-15

    We have measured the fusion excitation function for the {sup 9}Li+{sup 208}Pb reaction for near-barrier projectile center-of-mass energies of 23.9 to 43.0 MeV using the ISAC2 facility at TRIUMF. The {alpha}-emitting evaporation residues ({sup 211-214}At) were stopped in the {sup 208}Pb target, and their decay was measured. The isotopic yields at each energy were in good agreement with the predictions of a statistical model code (HIVAP). The measured fusion excitation function shows evidence for substantial sub-barrier fusion enhancement not predicted by current theoretical models. There is a suppression of the above barrier cross sections relative to these model predictions. The implications of this measurement for studying the fusion of {sup 11}Li with {sup 208}Pb are discussed.

  6. Complete Electric Dipole Strength and Neutron Skin in 208Pb

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, P.; Poltoraska, I.; Tamii, A.

    2013-03-01

    Small-angle polarized proton scattering including 0° on 208Pb has been studied at the RCNP cyclotron with high energy resolution of the order 25 -- 30 keV (FWHM). The complete E1 strength distribution from 5 to 20 MeV could be extracted from the data. The total E1 polarizability as well as the properties of the pygmy dipole resonance can be extracted with high precision providing important experimental constraints on the neutron skin thickness in 208Pb and the symmetry energy of neutron matter.

  7. Multinucleon transfer reactions in the 40Ar+208Pb system

    NASA Astrophysics Data System (ADS)

    Mijatović, T.; Szilner, S.; Corradi, L.; Montanari, D.; Pollarolo, G.; Fioretto, E.; Gadea, A.; Goasduff, A.; Malenica, D. Jelavić; Mǎrginean, N.; Milin, M.; Montagnoli, G.; Scarlassara, F.; Soić, N.; Stefanini, A. M.; Ur, C. A.; Valiente-Dobón, J. J.

    2016-12-01

    We measured multinucleon transfer reactions in the 40Ar+208Pb system at an energy close to the Coulomb barrier, by employing the PRISMA magnetic spectrometer. We extracted differential and total cross sections of the different transfer channels, with a careful investigation of the total kinetic energy loss distributions. Comparisons between different systems having the same 208Pb target and with projectiles going from neutron-poor to neutron-rich nuclei, i.e., 40Ca, 58Ni, and 40Ar, as well as between the data and GRAZING calculations have been carried out. The neutron-rich (stable) 40Ar beam allowed us to get access to the channels involving proton pickup, whose behavior in connection with the production of neutron-rich heavy partner has been outlined.

  8. Centrality Dependence of Neutral Pion Production in 158A GeV {sup 208}Pb+{sup 208}Pb Collisions

    SciTech Connect

    Aggarwal, M.M.; Bhatia, V.S.; Agnihotri, A.; Bhalla, K.B.; Gupta, S.K.; Raniwala, R.; Raniwala, S.; Ahammed, Z.; Chattopadhyay, S.; Das, A.C.; Dutta Majumdar, M.R.; Ganti, M.S.; Mukhopadhyay, D.S.; Nayak, T.K.; Sinha, B.C.; Trivedi, M.D.; Viyogi, Y.P.; Angelis, A.L.; Donni, P.; Foka, P.; Kalechofsky, H.; Martin, M.; Naef, H.; Rosselet, L.; Rubio, J.M.; Solomey, N.; Voeroes, S.; Antonenko, V.; Cherbatchev, R.; Doubovik, I.; Fokin, S.; Ippolitov, M.; Karadjev, K.; Koutcheryaev, I.; Lebedev, A.; Manko, V.; Mgebrichvili, G.; Nianine, A.; Sibiriak, I.; Tsvetkov, A.; Vinogradov, A.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Baldine, A.; Barabach, L.; Batiounia, B.; Chalyshev, V.; Djordjadze, V.; Frolov, V.; Gavrishchuk, O.; Guskov, B.; Kosarev, I.; Kuzmin, N.; Maximov, A.; Mehdiyev, R.; Mikhalev, D.; Myalkovski, V.; Nikitine, V.; Nikolaev, S.; Nomokonov, P.; Parfenov, A.; Pavliouk, S.; Roufanov, I.; Shabratova, G.; Slavine, N.; Vodopianov, A.; Awes, T.C.; Kim, H.; Plasil, F.; Stankus, P.; Young, G.R.; Baba, P.V.; Badyal, S.K.; Rao, N.K.; Sambyal, S.S.; Barlag, C.; Bathe, S.; Blume, C.; Bohne, E.; Boeroecz, Z.K.; Bucher, D.; Buesching, H.; Claussen, A.; Glasow, R.; Kampert, K.; Kees, S.; Kruempel, T.; Pietzmann, T.; Reygers, K.; Santo, R.; Schlagheck, H.; Stueken, D.; Bernier, T.; Gutbrod, H.H.; Luquin, L.; Nayak, S.K.; Pinanaud, W.; Retiere, F.; Roy, C.; Bock, R.; Kolb, B.W.; Langbein, I.; Lee, Y.Y.; Neumaier, S.; and others

    1998-11-01

    The production of neutral pions in 158A GeV {sup 208}Pb+ {sup 208}Pb collisions has been studied in the WA98 experiment at the CERN Super Proton Synchrotron (SPS). Transverse momentum spectra are studied for the range 0.3{le}m{sub T}{minus}m{sub 0}{le}4.0 GeV /c . The results for central collisions are compared to various models. The centrality dependence of the neutral pion spectral shape and yield is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with greater than about 30thinspthinspparticipating nucleons. This is most naturally explained by assuming an equilibrated system. {copyright} {ital 1998} {ital The American Physical Society }

  9. Distribution of M1 transitions in /sup 208/Pb

    SciTech Connect

    Laszewski, R.M.; Alarcon, R.; Dale, D.S.; Hoblit, S.D.

    1988-10-10

    The distribution of M1 strength in /sup 208/Pb has been measured between 5.8 and 7.4 MeV with highly polarized tagged photons. ..sigma..GAMMA/sup 2//sub 0/(M/sup 1/)/GAMMA = 14.6 +- /sup +1.5//sub -1.3/ eV corresponding to ..sigma..B(M1up-arrow) = 10.7 +- /sup +1.1//sub -0.9/..mu../sup 2//sub N/ was found, and can fully account for the much discussed ''missing'' M1 in /sup 208/Pb. When the present result is combined with known 1/sup 1/ transitions above neutron threshold, an M1 giant resonance emerges at 7.3 MeV, 1 MeV wide, with ..sigma..B(M1up-arrow)approx. =15.6..mu../sup 2//sub N/. Smaller 1/sup +/ resonances are also seen in both 5.85 and 6.24 MeV. The total M1 strength below 6.4 MeV amounts to ..sigma..B(M) = (1.9/sup +0.7//sub -0.4/)..mu../sup 2//sub N/.

  10. Proton particle-hole states in 208Pb

    NASA Astrophysics Data System (ADS)

    Grabmayr, P.; Mairle, G.; Schmidt-Rohr, U.; Berg, G. P. A.; Meissburger, J.; von Rossen, P.; Tain, J. L.

    1987-07-01

    Differential cross sections for the 209Bi(d, 3He) 208Pb transitions to the proton particle-proton hole states in 208Pb were obtained with the 45 MeV analyzed deuteron beam from the JULIC cyclotron and the high resolution spectrograph BIG KARL. 72 states up to 6.6 MeV were studied with an overall resolution of 12 to 15keV. Spectroscopic factors were extracted relative to the simultaneously measured calibration reaction 208Pb(d, 3He) 207Tl. For 26 states new parity assignments were possible on the basis of the measured angular distributions. The deduced inclusion into one of the four multiplets put limits on the possible spins of the states in question. With the help of sum rule arguments the spins of 12 states were assigned. The comparison with shell model calculations give only rough agreement as they predict the energies of the respective states about 300 keV too high. The magnetic dipole state at 5.846 MeV was observed with a Spectroscopic factor C2S = 0.17. From this, together with the transition probability B(M1↑) = (1.6 ± 0.5) μN2 from a ( overlineγ, γ') experiment we derived size and relative sign of the dominant neutron and proton spin-flip amplitudes. The result gives clear evidence for the isoscalar character of this state in accordance wtih TDA and RPA predictions. The matrix elements of the two-body residual interaction were derived unambiguously for the h{9}/{2} ∗ s{1}/{2}and h{9}/{2} ∗ d{3}/{2} multiplets. For the h{9}/{2}∗ h{11}/{2} and h{9}/{2} ∗ d{5}/{2} multiplets uncertainties are larger because of assumptions of some of the spins for the states of high excitation energy. The four monopole terms are found close to the average of -308 keV. They are dominated by the Coulomb contributions of ≈ - 216 keV. The deduced J-dependence of the matrix elements differs from those found in other systematic investigations indicating more complicated underlying nuclear forces must contribute.

  11. Measurement of internal pairs from {sup 206}Pb

    SciTech Connect

    Ahmad, I.; Back, B.B.; Betts, R.R.

    1995-08-01

    The failure to observe sharp sum-energy lines in measurements of {sup 238}U + {sup 181}Ta and {sup 238}U + {sup 232}Th raises the issue of the correct functioning of APEX under in-beam conditions. Extensive measurements with electron and pair emitting sources were used to demonstrate the resolution and acceptance of APEX, but the possibility remains that some unforeseen background or other effects might compromise the ability to see peaks in-beam. In order to test the functioning of APEX under the most stringent conditions, we also performed a measurement of internal pairs produced in the decay of the 2.648-MeV 3{sup -} state in {sup 206}Pb to the 2{sup +} state at 0.803 MeV. The 3{sup -} state was excited in the {sup 206}Pb + {sup 206}Pb reaction at 5.9 MeV/u with a cross section of roughly 40 mb, resulting in an expected pair cross section of approximately 16 {mu}b. It should be emphasized that this measurement represents a much stricter test of the functioning of the apparatus than the observation of sum-energy lines would represent, as the internal pair measurement requires a Doppler shift correction before the transition can be seen. These data were analyzed and clearly show the expected peak. A Doppler-corrected sum-energy spectrum showing the expected IPC line at 823 keV. At present we are evaluating the acceptance of APEX for events of this type but it is clear that the observed yield is close to expectations.

  12. Use of stable lead isotopes and trace metals to characterize air mass sources into the eastern North Atlantic

    NASA Astrophysics Data System (ADS)

    VéRon, Alain J.; Church, Thomas M.

    1997-12-01

    Stable lead isotopes (204Pb, 206Pb, 207Pb, 208Pb) and trace metals (Mn, Al, Fe, Ni, Cu, Cd, Zn, Pb) have been analyzed in aerosol collected during the Atlantic Stratocumulus Transition Experiment-Marine Aerosol and Gas Exchange (ASTEX-MAGE) cruise that transited between Miami and the Azores from May to July 1992. Our goal was to define the continental signatures of the air masses encountered between the Azores and the subtropical regions. The combination of air mass trajectories, trace metal concentrations and stable lead isotopes allowed us to characterize the anthropogenic character of encountered air masses. The average 206Pb/207Pb ratio was 1.148±0.021 and corresponded to a mixing between well defined European (such as Great Britain with 1.115<206Pb/207Pb<1.125 and France with 206Pb/207Pb=1.141±0.000) and North American sources (with 206Pb/207Pb=1.184±0.000). On the basis of air mass trajectories and trace metal concentrations, the background isotopic signature associated with the trade winds (206Pb/207Pb=1.161±0.004) is consistent with previous reports by Church et al. [1990] such as 206Pb/207Pb=1.154±0.004 in 1988, (Véron et al., 1993), 206Pb/207Pb=1.155±0.004 in 1989, and Hamelin et al. [1996] (206Pb/207Pb=1.158±0.006) in 1991. Short-term variations of continental air mass sources was particularly investigated by considering the anthropogenic character of aerosols collected during two Lagrangian experiments conducted as part of the ASTEX-MAGE cruise. We demonstrated the utility of stable lead isotopes to assign a "continental source signature" (or mixture thereof) to air masses beyond that normally possible by conventional air mass trajectory analysis in remote oceanic regions.

  13. New Neutron Rich Nuclei Near {sup 208}Pb

    SciTech Connect

    Aeystoe, J.; Andreyev, A.; Evensen, A.-H.; Hoff, P.; Huhta, M.; Huyse, M.; ISOLDE Collaboration; Jokinen, A.; Karny, M.; Kugler, E.; Kurpeta, J.; Lettry, J.; Nieminen, A.; Plochocki, A.; Ramdhane, M.; Ravn, H.; Rykaczewski, K.; Szerypo, J.; VanDuppen, P.; Walter, G.; Woehr, A.

    1998-11-13

    The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may try to observe and understand the evolution of the nuclear structure while departing in the experiment as far as possible from the stable nuclei. An extension of experimental nuclear structure studies towards the nuclei characterized by high neutron excess is crucial for such verifications as well as for the {tau}-process nucleosynthesis scenario. Heavy neutron-rich nuclei, south-east of doubly-magic {sup 208}Pb, were always very difficult to produce and investigate. The nuclei like {sup 218}Po and {sup 214}Pb or {sup 210}Tl marked the border line of known nuclei from the beginning of the radioactivity era for over ninety years. To illustrate the difficulties, one can refer to the experiments employing the on-line mass separator technique. A spallation of heavy targets like {sup 232}Th and {sup 238}U by high-energy protons was proven as a source of heavy neutron-rich nuclei. The isotopes near and beyond doubly-magic {sup 208}Pb were produced too. However, such studies often suffered from an isobaric contamination of much more strongly produced and efficiently released elements like francium or radon and their decay products. A new experimental technique, based on the pulsed release element selective method recently developed at the PS Booster-ISOLDE at CERN [7,8,9] greatly reduces the contamination of these very short-lived {alpha}-emitters (Z {ge} 84) for the isobaric mass chains A=215 to A=218.

  14. NMR absolute shielding scale and nuclear magnetic dipole moment of (207)Pb.

    PubMed

    Adrjan, Bożena; Makulski, Włodzimierz; Jackowski, Karol; Demissie, Taye B; Ruud, Kenneth; Antušek, Andrej; Jaszuński, Michał

    2016-06-28

    An absolute shielding scale is proposed for (207)Pb nuclear magnetic resonance (NMR) spectroscopy. It is based on ab initio calculations performed on an isolated tetramethyllead Pb(CH3)4 molecule and the assignment of the experimental resonance frequency from the gas-phase NMR spectra of Pb(CH3)4, extrapolated to zero density of the buffer gas to obtain the result for an isolated molecule. The computed (207)Pb shielding constant is 10 790 ppm for the isolated molecule, leading to a shielding of 10799.7 ppm for liquid Pb(CH3)4 which is the accepted reference standard for (207)Pb NMR spectra. The new experimental and theoretical data are used to determine μ((207)Pb), the nuclear magnetic dipole moment of (207)Pb, by applying the standard relationship between NMR frequencies, shielding constants and nuclear moments of two nuclei in the same external magnetic field. Using the gas-phase (207)Pb and (reference) proton results and the theoretical value of the Pb shielding in Pb(CH3)4, we find μ((207)Pb) = 0.59064 μN. The analysis of new experimental and theoretical data obtained for the Pb(2+) ion in water solutions provides similar values of μ((207)Pb), in the range of 0.59000-0.59131 μN.

  15. Isotopic signatures for natural versus anthropogenic Pb in high-altitude Mt. Everest ice cores during the past 800 years.

    PubMed

    Lee, Khanghyun; Hur, Soon Do; Hou, Shugui; Burn-Nunes, Laurie J; Hong, Sungmin; Barbante, Carlo; Boutron, Claude F; Rosman, Kevin J R

    2011-12-15

    A long-term record, extending back 800 years (1205 to 2002 AD), of the Pb isotopic composition ((206)Pb/(207)Pb and (208)Pb/(207)Pb) as well as Pb concentrations from high altitude Mt. Everest ice cores has the potential to identify sources and source regions affecting natural and anthropogenic Pb deposition in central Asia. The results show that the regional natural background Pb isotope signature (~1.20 for (206)Pb/(207)Pb and ~2.50 for (208)Pb/(207)Pb) in the central Himalayas was dominated by mineral dust over the last ~750 years from 1205 to 1960s, mostly originating from local sources with occasional contributions of long-range transported dust probably from Sahara desert and northwestern India. Since the 1970s, the Pb isotope ratios are characterized by a continuous decline toward less radiogenic ratios with the least mean ratios of 1.178 for (206)Pb/(207)Pb and 2.471 for (208)Pb/(207)Pb in the period 1990-1996. The depression of the (206)Pb/(207)Pb and (208)Pb/(207)Pb values during the corresponding periods is most likely due to an increasing influence of less radiogenic Pb of anthropogenic origin mainly from leaded gasoline used in South Asia (India as well as possibly Bangladesh and Nepal). From 1997 to 2002, isotopic composition tends to show a shift to slightly more radiogenic signature. This is likely attributed to reducing Pb emissions from leaded gasoline in source regions, coinciding with the nationwide reduction of Pb in gasoline and subsequent phase-out of leaded gasoline in South Asia since 1997. An interesting feature is the relatively high levels of Pb concentrations and enrichment factors (EF) between 1997 and 2002. Although the reason for this feature remains uncertain, it would be probably linked with an increasing influence of anthropogenic Pb emitted from other sources such as fossil fuel combustion and non-ferrous metal production.

  16. Electric dipole excitation of 208Pb by polarized electron impact

    NASA Astrophysics Data System (ADS)

    Jakubassa-Amundsen, D. H.; Ponomarev, V. Yu.

    2016-03-01

    The cross sections and spin asymmetries for the excitation of 1- states in 208Pb by transversely polarized electrons with collision energy of 30-180MeV have been examined within the DWBA scattering formalism. As examples, we have considered a low-lying 1- state and also states belonging to the pygmy dipole and giant dipole resonances. The structure of these states and their corresponding transition charge and current densities have been taken from an RPA calculation within the quasiparticle phonon model. The complex-plane rotation method has been applied to achieve the convergence of the radial DWBA integrals for backward scattering. We have studied the behaviour of the cross sections and spin asymmetries as a function of electron energy and scattering angle. The role of the longitudinal and transversal contributions to the excitation has been thoroughly studied. We conclude that the spin asymmetry S, related to unpolarized outgoing electrons, is mostly well below 1% even at the backward scattering angles and its measurement provides a challenge for future experiments with polarized electrons.

  17. Influences upon the lead isotopic composition of organic and mineral horizons in soil profiles from the National Soil Inventory of Scotland (2007-09).

    PubMed

    Farmer, John G; Graham, Margaret C; Eades, Lorna J; Lilly, Allan; Bacon, Jeffrey R

    2016-02-15

    Some 644 individual soil horizons from 169 sites in Scotland were analyzed for Pb concentration and isotopic composition. There were three scenarios: (i) 36 sites where both top and bottom (i.e. lowest sampled) soil horizons were classified as organic in nature, (ii) 67 with an organic top but mineral bottom soil horizon, and (iii) 66 where both top and bottom soil horizons were mineral. Lead concentrations were greater in the top horizon relative to the bottom horizon in all but a few cases. The top horizon (206)Pb/(207)Pb ratio was lesser (outside analytical error) than the corresponding bottom horizon (206)Pb/(207)Pb ratio at (i) 64%, (ii) 94% and (iii) 73% of sites, and greater at only (i) 8%, (ii) 3% and (iii) 8% of sites. A plot of (208)Pb/(207)Pb vs. (208)Pb/(206)Pb ratios showed that the Pb in organic top (i, ii) and bottom (i) horizons was consistent with atmospherically deposited Pb of anthropogenic origin. The (206)Pb/(207)Pb ratio of the organic top horizon in (ii) was unrelated to the (206)Pb/(207)Pb ratio of the mineral bottom horizon as demonstrated by the geographical variation in the negative shift in the ratio, a result of differences in the mineral horizon values arising from the greater influence of radiogenic Pb in the north. In (iii), the lesser values of the (206)Pb/(207)Pb ratio for the mineral top horizon relative to the mineral bottom horizon were consistent with the presence of anthropogenic Pb, in addition to indigenous Pb, in the former. Mean anthropogenic Pb inventories of 1.5 and 4.5 g m(-2) were obtained for the northern and southern halves of Scotland, respectively, consistent with long-range atmospheric transport of anthropogenic Pb (mean (206)Pb/(207)Pb ratio~1.16). For cultivated agricultural soils (Ap), this corresponded to about half of the total Pb inventory in the top 30 cm of the soil column.

  18. The influence of projectile neutron number in the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions

    SciTech Connect

    Dragojevic, Irena; Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Sudowe, R.; Nitsche, H.

    2008-07-11

    Four isotopes of rutherfordium,254-257Rf, were produced by the 208Pb(48Ti, xn)256-xRf and 208Pb(50Ti, xn)258-xRf reactions (x = 1, 2) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Excitation functions were measured for the 1n and 2n exit channels. A maximum likelihood technique, which correctly accounts for the changing cross section at all energies subtended by the targets, was used to fit the 1n data to allow a more direct comparison between excitation functions obtained under different experimental conditions. The maximum 1n crosssections of the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions obtained from fits to the experimental data are 0.38 +/- 0.07 nb and 40 +/-5 nb, respectively. Excitation functions for the 2n exit channel were also measured, with maximum cross sections of nb for the 48Ti induced reaction, and 15.7 +/- 0.2 nb for the 50Ti induced reaction. The impact of the two neutron difference in the projectile on the 1n cross section is discussed. The results are compared to the Fusion by Diffusion model developed by Swiatecki, Wilczynska, and Wilczynski.

  19. Chaos and Regularity in the Doubly Magic Nucleus 208Pb

    NASA Astrophysics Data System (ADS)

    Dietz, B.; Heusler, A.; Maier, K. H.; Richter, A.; Brown, B. A.

    2017-01-01

    High-resolution experiments have recently lead to a complete identification (energy, spin, and parity) of 151 nuclear levels up to an excitation energy of Ex=6.20 MeV in 208Pb [Heusler et al., Phys. Rev. C 93, 054321 (2016), 10.1103/PhysRevC.93.054321]. We present a thorough study of the fluctuation properties in the energy spectra of the unprecedented set of nuclear bound states. In a first approach, we group states with the same spin and parity into 14 subspectra, analyze standard statistical measures for short- and long-range correlations, i.e., the nearest-neighbor spacing distribution, the number variance Σ2, the Dyson-Mehta Δ3 statistics, and the novel distribution of the ratios of consecutive spacings of adjacent energy levels in each energy sequence, and then compute their ensemble average. Their comparison with a random matrix ensemble which interpolates between Poisson statistics expected for regular systems and the Gaussian orthogonal ensemble (GOE) predicted for chaotic systems shows that the data are well described by the GOE. In a second approach, following an idea of Rosenzweig and Porter [Phys. Rev. 120, 1698 (1960), 10.1103/PhysRev.120.1698], we consider the complete spectrum composed of the independent subspectra. We analyze their fluctuation properties using the method of Bayesian inference involving a quantitative measure, called the chaoticity parameter f , which also interpolates between Poisson (f =0 ) and GOE statistics (f =1 ). It turns out to be f ≈0.9 . This is so far the closest agreement with a GOE observed in the spectra of bound states in a nucleus. The same analysis is also performed with spectra computed on the basis of shell model calculations with different interactions (surface-delta interaction, Kuo-Brown, Michigan-three-Yukawa). While the simple surface-delta interaction exhibits features typical for nuclear many-body systems with regular dynamics, the other, more realistic interactions yield chaoticity parameters f close

  20. Large Pb Isotopic Variations in Pre-shield Stage Kilauea Magmas

    NASA Astrophysics Data System (ADS)

    Shimizu, N.; Sisson, T. W.; Layne, G. D.

    2001-12-01

    Volcaniclastic sediments found from a scarp below the mid-slope bench at water depths between 3,000 and 5,000m offshore south of Kilauea, Hawaii, contain abundant glass shards that represent submarine eruptions from an ancestral Kilauea volcano (Lipman et al., 2000; Sisson et al., 2001). Their major element compositions range from tholeiites/transitional basalts to alkali basalts to basanites and nephelinites. Pb isotopic compositions of the glasses were determined using a Cameca IMS 1270 ion microprobe at Woods Hole Oceanographic Institution. Replicate analyses of basalt glass stnadards show that 208Pb/206Pb and 207Pb/206Pb ratios could be determined in basalt glasses with external precisions better than 0.15% (1σ ) in a spot of 30 μ m across. Results show that: (1) a range of Pb isotopic compositions observed in the glasses are much greater than the entire spectrum of the Hawaiian volcanics. 208Pb/206Pb ratios vary from 2.099 to 2.004 and 207Pb/206Pb from 0.864 to 0.805. (2) There appear to be three distinct compositions, with each being represented by diverse magmatic compositions. There appears to be no significant mixing between them, and they form a linear array in a 208/206 vs 207/206 space, encompassing the entire Hawaiian Pb isotopic composition array. The least radiogenic composition (208Pb/206Pb=2.099, 207Pb/206Pb=0.864) in on an extension of the Honolulu Volcanics array, whereas the most radiogenic composition (208Pb/206Pb=2.004, 207Pb/206Pb=0.805) is far more radiogenic than any known Hawaiian magmas. The intermediate composition (208Pb/206Pb=2.041, 207Pb/206Pb=0.827) is close to the "Kea" endmember composition proposed by Eiler et al. (1998). The ancestral Kilauea nephelinites are derived from two distinct sources with radiogenic compositions and are quite distinct from all other Hawaiian post-erosional nephelinites. It is evident that diverse sources were tapped during the pre-shield stage Kilauea magmatism, and that melts erupted without mixing

  1. Measurements of neutron capture cross section for {sup 207,208}Pb

    SciTech Connect

    Segawa, M.; Toh, Y.; Harada, H.; Kitatani, F.; Koizumi, M.; Fukahori, T.; Iwamoto, N.; Iwamoto, O.; Oshima, M.; Hatsukawa, Y.; Nagai, Y.; Igashira, M.; Kamada, S.; Tajika, M.

    2014-05-02

    The neutron capture cross sections for {sup 207,208}Pb have been measured in the neutron energy region from 10 to 110 keV. The γ-rays cascaded from a capture state to the ground state or low-lying states of {sup 208,209}Pb were observed for the first time, using an anti-Compton Nal(Tl) spectrometer and a TOF method. The observed discrete γ-ray energy spectra enabled us to determine neutron capture cross sections for {sup 207,208}Pb with small systematic errors, since we could distinguish γ-ray of {sup 207,208}Pb(n,γ) reactions from background γ-ray with use of the γ-ray spectra. The obtained cross sections include both contributions of resonance and direct capture components different from the previous TOF measurements.

  2. Sensitivity of the electric dipole polarizability to the neutron skin thickness in {sup 208}Pb

    SciTech Connect

    Roca-Maza, X.; Agrawal, B. K.; Colo, G.; Nazarewicz, W.; Paar, N.; Piekarewicz, J.; Reinhard, P.-G.; Vretenar, D.

    2012-10-20

    The static dipole polarizability, {alpha}{sub D}, in {sup 208}Pb has been recently measured with highresolution via proton inelastic scattering at the Research Center for Nuclear Physics (RCNP) [1]. This observable is thought to be intimately connected with the neutron skin thickness, r{sub skin}, of the same nucleus and, more fundamentally, it is believed to be associated with the density dependence of the nuclear symmetry energy. The impact of r{sub skin} on {alpha}{sub D} in {sup 208}Pb is investigated and discussed on the basis of a large and representative set of relativistic and non-relativistic nuclear energy density functionals (EDF) [2].

  3. Two-parameter Fermi function fits to experimental charge and point-proton densities for 208Pb

    NASA Astrophysics Data System (ADS)

    Jones, Adam B.; Brown, B. Alex

    2014-12-01

    We use the model-independent experimental charge density for 208Pb to determine a model-independent point-proton density. An improved two-parameter Fermi function representation for the this point-proton density provides input for the analysis of experiments for the neutron density interpreted in terms of neutron skin and halo properties of 208Pb.

  4. Discrimination of the Cigarettes Geographical Origin by DRC-ICP-MS Measurements of Pb Isotope Compositions

    NASA Astrophysics Data System (ADS)

    Guo, W.; Hu, S.; Jin, L.

    2014-12-01

    Trace Pb are taken up with the same isotopic ratios as is present in the source soil, and the isotopic composition of Pb could used to reflect these sources and provide powerful indicators of the geographic origin of agriculture products derived from vegetative matter. We developed a simple and high throughput method, which based on DRC-ICP-MS for determination of Pb isotope ratios for discriminating the geographic origin of cigarettes. After acid digestion procedure, the cigarette digested solutions were directly analyzed by ICP-QMS with a DRC pressurized by the non-reactive gas Ne. In the DRC, Ne molecules collision with Pb ions and improves Pb isotope ratios precision 3-fold, which may be due to the collisional dampling smoothes out the ion beam fluctuations. Under the optimum DRC rejection parameter Q (RPq = 0.45), the main matrix components (K, Na, Ca, Mg, Al, Fe etc.) originating from cigarettes were filtered out. Mass discrimination of 208Pb/206Pb ratio in Ne DRC mode increased 0.3% compared to the standard mode, the mass bias due to the in-cell Ne gas collision can be accurately corrected by NIST 981 Pb isotope standard. This method was verified by a tobacco reference material CTV-OTL-2. Results of 208Pb/206Pb and 207Pb/206Pb were 2.0848 ± 0.0028 (2δ) and 0.8452 ± 0.0011 (2δ) for CTA-VTL-2, which were agreed with the literature values (208Pb/206Pb = 2.0884 ± 0.0090 and 207Pb/206Pb = 0.8442 ± 0.0032). The precision of Pb isotope ratios (208Pb/206Pb and 207Pb/206Pb) for the cigarette samples are ranged from 0.01 to 0.08% (N = 5). It has sufficient precision to discriminate 91 different brand cigarettes originated from four different geographic regions (Shown in Fig).

  5. Elastic scattering of 17O+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.

    2016-05-01

    Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.

  6. Pb isotope composition in lichens and aerosols from eastern Sicily: Insights into the regional impact of volcanoes on the environment

    SciTech Connect

    Monna, F. ); Aiuppa, A.; Varrica, D. ); Dongarra, G. CNR, Palermo . Istituto Geochimica dei Fluidi)

    1999-08-01

    A total of 25 lichen thalli of Parmelia conspersa (Ehrh), collected at Vulcano island and at Mt. Etna, during a one-year biogeochemical survey, were analyzed for Pb, br, Al, Sc,[sup 206]Pb/[sup 207]Pb, and [sup 208]Pb/[sup 206]Pb ratios. Lead isotope ratios were also measured on aerosol samples from urban areas and industrial sites of Sicily. The observed [sup 206]Pb/[sup 207]Pb range for urban and industrial aerosols matches the anthropogenic signature. Lichens instead, are closer to the compositional field of [sup 206]Pb rich geogenic sources. This natural input is more evident at Vulcano island than at Mt. Etna, where the anthropogenic activities are considerably more effective. On the basis of lead isotope data, Pb/Br ratios and calculated lead enrichment factors, a natural lead pollution from volcanoes is suggested. Volcanic lead contribution ranges from 10 to 30% at Mt. Etna to 10--80% at Vulcano island.

  7. Isotopic evidence of pollutant lead sources in Northwestern France

    NASA Astrophysics Data System (ADS)

    Véron, Alain; Flament, Pascal; Bertho, Marie Laure; Alleman, Laurent; Flegal, Russell; Hamelin, Bruno

    Ratios of stable lead isotopes ( 204Pb, 206Pb, 207Pb, 208Pb) are used to characterize both spatial and temporal variations in anthropogenic emissions of industrial lead aerosols to the atmosphere of northwestern France. Differences in isotopic compositions of aerosols collected from a rural area (Wimereux) in the Nord-Pas de Calais region along the English Channel in 1982-1983 ( 206Pb/ 207Pb=1.108±0.005) and 1994 ( 206Pb/ 207Pb=1.148±0.003) are paralleled by similar variations in urban aerosols within France during the same period (e.g., 206Pb/ 207Pb=1.115±0.008 from 1981-1989 and 1.143±0.006 from 1992-1995). These results correlate well with recent findings in the Mediterranean basin (Alleman, 1997) where this radiogenicity increase is clearly associated with industrial sources other than leaded gasoline that has remained relatively constant during its phasing out ( 206Pb/ 207Pb=1.08-1.11). Here we used archived data, air mass trajectories and aerosol diameters combined with isotopic signatures to confirm this trend at a regional scale. Indeed, the main industrial signatures from lead smelting ( 206Pb/ 207Pb=1.133±0.001) and steel metallurgy ( 206Pb/ 207Pb=1.196±0.015) in northwestern France appear more radiogenic than that of leaded gasoline. The shift in isotopic compositions also conform with the systematic change in the mean size (diameter) of aerosols at Wimereux, which ranged from 0.30 to 0.61 μm in 1982-1984 and from 0.70 to 0.89 μm in 1994.

  8. A precise 232Th-208Pb chronology of fine-grained monazite: Age of the Bayan Obo REE-Fe-Nb ore deposit, China

    USGS Publications Warehouse

    Wang, Jingyuan; Tatsumoto, M.; Li, X.; Premo, W.R.; Chao, E.C.T.

    1994-01-01

    We have obtained precise Th-Pb internal isochron ages on monazite and bastnaesite for the world's largest known rare earth elements (REE)-Fe-Nb ore deposit, the Bayan Obo of Inner Mongolia, China. The monazite samples, collected from the carbonate-hosted ore zone, contain extremely small amounts of uranium (less than 10 ppm) but up to 0.7% ThO2. Previous estimates of the age of mineralization ranged from 1.8 to 0.255 Ga. Magnetic fractions of monazite and bastnaesite samples (<60-??m size) showed large ranges in 232Th 204Pb values (900-400,000) and provided precise Th-Pb internal isochron ages for paragenetic monazite mineralization ranging from 555 to 398 Ma within a few percent error (0.8% for two samples). These results are the first indication that REE mineralization within the giant Bayan Obo ore deposit occurred over a long period of time. The initial lead isotopic compositions (low 206Pb 204Pb and high 208Pb 204Pb) and large negative ??{lunate}Nd values for Bayan Obo ore minerals indicate that the main source(s) for the ores was the lower crust which was depleted in uranium, but enriched in thorium and light rare earth elements for a long period of time. Zircon from a quartz monzonite, located 50 km south of the ore complex and thought to be related to Caledonian subduction, gave an age of 451 Ma, within the range of monazite ages. Textural relations together with the mineral ages favor an epigenetic rather than a syngenetic origin for the orebodies. REE mineralization started around 555 Ma (disseminated monazite in the West, the Main, and south of the East Orebody), but the main mineralization (banded ores) was related to the Caledonian subduction event ca. 474-400 Ma. ?? 1994.

  9. Enhanced E1 transitions and {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po

    SciTech Connect

    Suzuki, Y.; Ohkubo, S.

    2010-10-15

    We formulate a model for {sup 212}Po, based on the coupled-channels of {alpha}+{sup 208}Pb(0{sup +}) and {alpha}+{sup 208}Pb(3{sup -}) in which the {alpha}-Pb interaction contains scalar, quadrupole, and octupole terms. The model reproduces the recently observed enhanced E1 transitions from the several new negative-parity levels to the yrast states. Because these data are hard to understand in the shell model, this success gives a strong support for a unique role of {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po.

  10. Reanalysis of muonic {sup 90}Zr and {sup 208}Pb atoms

    SciTech Connect

    Haga, Akihiro; Toki, Hiroshi; Horikawa, Yataro

    2007-04-15

    Muonic transition energies in lowlying {mu}{sup -}-{sup 90}Zr and {mu}{sup -}-{sup 208}Pb states are reanalyzed by using nuclear polarization with the full-electromagnetic nuclear response. The possibility of the observed enhancement of the energy-weighted sum rule is also considered in the analysis. The transverse part of the nuclear polarization and the enhancement effect play an important role in improving the fine structure splitting of muonic p-states in both nuclei. Furthermore, introducing a pygmy dipole resonance in the excitation spectrum, the final fit drastically improves in {sup 208}Pb. However, there remains a discrepancy in {sup 90}Zr, for which the structure of the nuclear excitation spectrum is insensitive to the nuclear-polarization energy shift. Therefore, the remaining discrepancy might be caused by effects other than the nuclear polarization.

  11. Measurement of the 208Pb(52Cr, n)259Sg Excitation Function

    SciTech Connect

    Folden III, C.M.; Dragojevic, I.; Dullmann, Ch.E.; Eichler, R.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Sudowe, R.; Gregorich, K.E.; Hoffman, D.C.; Nitsche, H.

    2010-03-19

    The excitation function for the 208Pb(52Cr, n)259Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from 259Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the 208Pb(52Cr, 2n)258Sg reaction was obtained, and an improved 258Sg half-life of ms was calculated by combining all available experimental data.

  12. Excitation energy dependence of the level density parameter close to the doubly magic 208Pb

    NASA Astrophysics Data System (ADS)

    Roy, Pratap; Banerjee, K.; Bhattacharya, C.; Pandey, R.; Sen, A.; Manna, S.; Kundu, S.; Rana, T. K.; Ghosh, T. K.; Mukherjee, G.; Roy, T.; Dhal, A.; Dey, A.; Meena, J. K.; Saha, A. K.; Pandit, Deepak; Mukhopadhyay, S.; Bhattacharya, S.

    2016-12-01

    Neutron evaporation spectra have been measured from 4He+208Pb and 4He+209Bi reactions by using 4He-ion beams of several bombarding energies. Excitation-energy dependence of the level density parameter has been studied for the two systems in the excitation energy range of ˜18 -50 MeV. For both the reactions an overall reduction of the asymptotic level density parameter with increasing excitation energy (temperature) is observed. The trend of the data was compared with the Thomas-Fermi model predictions and found to be in reasonable agreement. The value of the shell damping parameter has been extracted from the lowest-energy data in the case of Po,211210 and At,212211 nuclei close to the Z =82 and N =126 shell closure, and it was found to be consistent with the recent measurement in the vicinity of doubly magic 208Pb nucleus.

  13. Isoscalar giant dipole resonance in {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb

    SciTech Connect

    Clark, H. L.; Lui, Y.-W.; Youngblood, D. H.

    2001-03-01

    Strength functions for isoscalar dipole excitations in {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb have been measured with inelastic scattering of 240 MeV {alpha} particles at small angles. The isoscalar E1 strength distribution in each nucleus is found to consist of a broad component at E{sub x}{approx}114/A{sup 1/3}MeV containing approximately 100% of the E1 EWSR and a narrower one at E{sub x}{approx}72/A{sup 1/3}MeV containing 15--28% of the total isoscalar E1 strength. The higher component is the compression mode E1 strength previously reported only in {sup 208}Pb, whereas the lower component may be a new mode not reported previously, but suggested by recent RPA-HF and relativistic mean field calculations.

  14. Production and identification of new, neutron-rich nuclei in the [sup 208]Pb region

    SciTech Connect

    Rykaczewski, K. ); Szerypo, J.; Evensen, A.-H.; Kugler, E.; Lettry, J.; Ravn, H. ); Kurpeta, J.; Pkochocki, A.; Karny, M.; Szerypo, J. ); Szerypo, J. ); Andreyev, H.; Huyse, M.; Wo uml; hr, A. ); Aystuml, J.; Nieminen, A.; Huhta, M. ); Walter, G. ) Hoff, P. )

    1998-12-01

    The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic [sup 208]Pb are briefly described. An identification of new neutron-rich isotopes [sup 215]Pb and [sup 217]Bi, and new decay properties of [sup 216]Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported. [copyright] [ital 1998 American Institute of Physics.

  15. Neutron skin of (208)Pb, nuclear symmetry energy, and the parity radius experiment.

    PubMed

    Roca-Maza, X; Centelles, M; Viñas, X; Warda, M

    2011-06-24

    A precise determination of the neutron skin Δr(np) of a heavy nucleus sets a basic constraint on the nuclear symmetry energy (Δr(np) is the difference of the neutron and proton rms radii of the nucleus). The parity radius experiment (PREX) may achieve it by electroweak parity-violating electron scattering (PVES) on (208)Pb. We investigate PVES in nuclear mean field approach to allow the accurate extraction of Δr(np) of (208)Pb from the parity-violating asymmetry A(PV) probed in the experiment. We demonstrate a high linear correlation between A(PV) and Δr(np) in successful mean field forces as the best means to constrain the neutron skin of (208)Pb from PREX, without assumptions on the neutron density shape. Continuation of the experiment with higher precision in A(PV) is motivated since the present method can support it to constrain the density slope of the nuclear symmetry energy to new accuracy.

  16. Precise measurement of near-barrier 8He+208Pb elastic scattering: Comparison with 6He

    NASA Astrophysics Data System (ADS)

    Marquínez-Durán, G.; Martel, I.; Sánchez-Benítez, A. M.; Acosta, L.; Berjillos, R.; Dueñas, J.; Rusek, K.; Keeley, N.; Álvarez, M. A. G.; Borge, M. J. G.; Chbihi, A.; Cruz, C.; Cubero, M.; Fernández-García, J. P.; Fernández-Martínez, B.; Flores, J. L.; Gómez-Camacho, J.; Kemper, K. W.; Labrador, J. A.; Marqués, M.; Moro, A. M.; Mazzocco, M.; Pakou, A.; Parkar, V. V.; Patronis, N.; Pesudo, V.; Pierroutsakou, D.; Raabe, R.; Silvestri, R.; Soic, N.; Standyło, Ł.; Strojek, I.; Tengblad, O.; Wolski, R.; Abou-Haidar, Z.

    2016-12-01

    Dramatic differences in the elastic scattering of the neutron rich nuclei 6He and 8He are found when new high quality data for the 8He+208Pb system are compared with previously published 6He+208Pb data at the same laboratory frame incident energy. The new 8He data are of the same level of detail as for stable beams. When comparing them with those previously obtained for 6He+208Pb at the same energy, it is possible to determine from the data alone that 6He has a much longer range absorption than 8He. However, both nuclei show significant absorption beyond their strong absorption radii. While it has been known for a long time that elastic scattering at energies around the barrier only determines the optical potential over a small distance in radial space, typically ±0.5 fm or so, both the 6He and the 8He imaginary potentials obtained from various optical model fits to these data are the same over a much wider range of ±1.5 fm.

  17. 207Pb and 205Tl NMR on Perovskite Type Crystals APbX3 (A = Cs, Tl, X = Br, I)

    NASA Astrophysics Data System (ADS)

    Sharma, Surendra; Weiden, Norbert; Weiss, Alarich

    1987-11-01

    By 205Tl and 207Pb NM R the chemical shift in polycrystalline samples of binary halides AX, BX2 and ternary halides ABX3 (A = Cs, Tl; B = Pb; X = Br, I) was studied at room temperature. The chemical shift tensors δ ( 205Tl) and δ (207Pb) were determined in magnitude and orientation on single crystals of the orthorhombic TlPbI3. The components of the δ(205Tl) tensor are δx (205Tl) || a = 611ppm; δy (205Tl) || b = 680 ppm; δZ(205Tl) || c = 1329 ppm; δiso(205Tl) = 873.3 ppm (with respect to 3.4 molar aqueous solution of TlOOCCH3). The chemical shift tensor of 207Pb in TlPbI3 shows two orientations. One of them is: δx (207Pb) = 3760 ppm, inclined 30° from b towards c, δy(207Pb) || a = 3485 ppm, δz(207Pb) = 2639 ppm inclined 120° from b towards c. δiso(207Pb) = 3295 ppm (with respect to saturated aqueous solution of Pb(NO3)2). The results are discussed with respect to the crystal structure and a model to explain orientation and anisotropy of the tensors δ(205Tl) and δ(207Pb) in TlPbI3 is proposed. In the system CsPbBr3-x Ix δ(207Pb) was studied on polycrystalline samples. The chemical shift increases with increasing x and negative excess shift is observed.

  18. Influence of single-neutron stripping on near-barrier 6He+208Pb and 8He+208Pb elastic scattering

    NASA Astrophysics Data System (ADS)

    Marquínez-Durán, G.; Keeley, N.; Kemper, K. W.; Mackintosh, R. S.; Martel, I.; Rusek, K.; Sánchez-Benítez, A. M.

    2017-02-01

    The influence of single-neutron stripping on the near-barrier elastic scattering angular distributions for the He,86+208Pb systems is investigated through coupled reaction channels (CRC) calculations fitting recently published data to explore the differences in the absorptive potential found in the scattering of these two neutron-rich nuclei. The inclusion of the coupling reduces the elastic cross section in the Coulomb-nuclear interference region for 8He scattering, whereas for 6He its major impact is on the large-angle elastic scattering. The real and imaginary dynamic polarization potentials are obtained by inverting the CRC elastic scattering S -matrix elements. These show that the main absorptive features occur between 11 and 12 fm for both projectiles, while the attractive features are separated by about 1 fm, with their main structures occurring at 10.5 fm for 6He and 11.5 fm for 8He.

  19. Study of the charge radii of the stable lead isotopes

    SciTech Connect

    Borchert, G.L.; Schult, O.W.B.; Speth, J.; Hansen, P.G.; Jonson, B.; Ravn, H.; McGrory, J.B.

    1982-01-01

    Isotope shifts have been measured of the K/sub ..cap alpha..l/ x-ray lines emitted after photo ionization of /sup 204/Pb, /sup 206/Pb, /sup 207/Pb and /sup 208/Pb samples. The results are compared with theoretical values for delta < r/sup 2/> calculated with a microscopic model. The x-ray shift data are also compared with optical data and the nuclear parameters lambda derived from electron scattering results.

  20. Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier

    SciTech Connect

    Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.

    2011-10-28

    We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

  1. Neutron skins of 208Pb and 48Ca from pionic probes

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    2012-12-01

    The neutron skin of 208Pb has received considerable attention in recent years. A variety of strongly-interacting probes depict a rather consistent picture but pionic probes have not been referred to in this context. We present here neutron-skin values from pionic atoms and from total reaction cross sections of π+ between 0.7 and 2 GeV/c which fit well into the picture. In addition we show that a neutron-skin for 48Ca can be obtained from existing data on pionic atoms and the result agrees with pion scattering experiments and with the scattering of α particles.

  2. Uncertainty analysis of 208Pb neutron skin predictions with chiral interactions

    DOE PAGES

    Sammarruca, Francesca

    2015-09-14

    Here, we report predictions for the neutron skin in 208Pb using chiral two- and three-body interactions at increasing orders of chiral effective field theory and varying resolution scales. Closely related quantities, such as the slope of the symmetry energy, are also discussed. As a result, the sensitivity of the skin to just pure neutron matter pressure when going from order 2 to order 4 of chiral effective theory is singled out in a set of calculations that employ an empirical equation of state for symmetric nuclear matter.

  3. Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering

    DOE PAGES

    Abrahamyan, Sergey; Albataineh, Hisham; Aniol, Konrad; ...

    2012-03-15

    We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from 208Pb. APV is sensitive to the radius of the neutron distribution (Rn). The result APV = 0.656 ± 0.060 (stat) ± 0.013 (syst) corresponds to a difference between the radii of the neutron and proton distributions Rn-Rp = 0.33-0.18+0.16 fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

  4. The pairing correlation study in the {sup 40}Ar+{sup 208}Pb reaction

    SciTech Connect

    Mijatović, T. Szilner, S.; Malenica, D. Jelavić; Prepolec, L.; Soić, N.; Tokić, V.; Corradi, L.; Fioretto, E.; Goasduff, A.; Stefanini, A. M.; Dobón, J. J. Valiente; Montanari, D.; Courtin, S.; Haas, F.; Montagnoli, G.; Scarlassara, F.; Ur, C. A.; Pollarolo, G.

    2015-10-15

    The multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb has been measured at E{sub lab} = 260 MeV with the large solid angle magnetic spectrometer PRISMA. Mass and charge yields, differential and total cross sections, total kinetic energy loss distributions of different channels were simultaneously studied. Angular distributions were measured in a wide angular range by matching three different angular settings of the spectrometer. Absolute cross sections were obtained after the response function of the spectrometer was evaluated. These cross sections for different transfer channels allow the discussion of the role played by nucleon-nucleon correlations.

  5. Sub-Barrier Fusion in the HI + 208Pb Systems and Nuclear Potentials for Cluster Decay

    SciTech Connect

    Sagaidak, R.N.; Tretyakova, S.P.; Khlebnikov, S.V.; Ogloblin, A.A.; Rowley, N.

    2005-11-21

    Near-barrier fusion excitation functions for the 12,14C, 16,18O + 208Pb reactions have been analyzed in the framework of the barrier-passing model using different forms of the nuclear potential and the phenomenology of a fluctuating barrier. The best-fit fusion potentials were used to estimate cluster decay probabilities from the corresponding ground states of Ra and Th, i.e., for the inverse decay process. The analysis supports the 'alpha-decay-like' scenario for carbon and oxygen emission from these nuclei.

  6. Multinucleon transfer processes in {sup 40}Ca+{sup 208}Pb

    SciTech Connect

    Szilner, S.; Corradi, L.; Behera, B.R.; Fioretto, E.; Gadea, A.; Latina, A.; Stefanini, A.M.; Trotta, M.; Vinodkumar, A.M.; Wu, Y.; Pollarolo, G.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Haas, F.

    2005-04-01

    Multinucleon transfer reactions in {sup 40}Ca+{sup 208}Pb have been studied at bombarding energies close to the Coulomb barrier. Projectilelike fragments have been identified in nuclear mass and charge with a time-of-flight spectrometer. Angular and total kinetic energy loss distributions and inclusive cross sections have been compared with those of semiclassical models. The analysis shows that a successive transfer mechanism of single nucleons does not account for the data, and a direct nucleon pair transfer has to be included in the description. Nucleon evaporation effects are taken into account.

  7. The pygmy dipole strength, the neutron radius of 208Pb and the symmetry energy

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Brenna, M.; Centelles, M.; Colò, G.; Mizuyama, K.; Pozzi, G.; Viñas, X.; Warda, M.

    2012-02-01

    The accurate characterization of the nuclear symmetry energy and its density dependence is one of the outstanding open problems in nuclear physics. A promising nuclear observable in order to constrain the density dependence of the symmetry energy at saturation is the neutron skin thickness of medium and heavy nuclei. Recently, a low-energy peak in the isovector dipole response of neutron-rich nuclei has been discovered that may be correlated with the neutron skin thickness. The existence of this correlation is currently under debate due to our limited experimental knowledge on the microscopic structure of such a peak. We present a detailed analysis of Skyrme Hartree-Fock (HF) plus random phase approximation (RPA) predictions for the dipole response in several neutron-rich nuclei and try to elucidate whether models of common use in nuclear physics confirm or dismiss its possible connection with the neutron skin thickness. Finally, we briefly present theoretical results for parity violating electron scattering on 208Pb at the conditions of the PREx experiment and discuss the implications for the neutron skin thickness of 208Pb and the slope of the symmetry energy.

  8. Diversity of neutron star properties at the fixed neutron-skin thickness of 208Pb

    NASA Astrophysics Data System (ADS)

    Alam, N.; Sulaksono, A.; Agrawal, B. K.

    2015-07-01

    We study the diversities in the properties of the neutron stars arising due to the different choices for the cross coupling between various mesons, which governs the density dependence of the nuclear symmetry energy in the extended relativistic mean-field (RMF) model. For this purpose, we obtain two different families of the extended RMF model corresponding to different nonlinear cross-coupling terms in the isovector part of the effective Lagrangian density. The lowest-order contributions for the δ mesons are also included. The different models within the same family yield wide variation in the value of neutron-skin thickness in the 208Pb nucleus. These models are employed to compute the neutron-star properties such as core-crust transition density, radius and red shift at canonical mass ( 1.4 M⊙) , tidal polarizability parameter, and threshold mass required for the enhanced cooling through the direct Urca process. Most of the neutron-star properties considered are significantly different(10-40%) for the different families of models at a smaller neutron-skin thickness (˜0.15 fm ) in the 208Pb nucleus.

  9. Examination of experimental evidence of chaos in the bound states of 208Pb

    NASA Astrophysics Data System (ADS)

    Muñoz, L.; Molina, R. A.; Gómez, J. M. G.; Heusler, A.

    2017-01-01

    We study the spectral fluctuations of the 208Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of 6.20 MeV recently identified at the Maier-Leibnitz Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of random matrix theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter ω , which takes the value ω =0 for regular systems and ω ≃1 for chaotic systems. We obtain ω =0.85 which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in 208Pb, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition, our results show that chaotic and nonchaotic nuclear states coexist in the same energy region of the spectrum.

  10. Investigation of off-site airborne transport of lead from a superfund removal action site using lead isotope ratios and concentrations

    USGS Publications Warehouse

    Pribil, Michael J.; Maddaloni, Mark A.; Staiger, Kimberly; Wilson, Eric; Magriples, Nick; Ali, Mustafa; Santella, Dennis

    2014-01-01

    Lead (Pb) concentration and Pb isotopic composition of surface and subsurface soil samples were used to investigate the potential for off-site air transport of Pb from a former white Pb processing facility to neighboring residential homes in a six block area on Staten Island, NY. Surface and subsurface soil samples collected on the Jewett White Pb site were found to range from 1.122 to 1.138 for 206Pb/207Pb and 2.393 to 2.411 for 208Pb/207Pb. The off-site surface soil samples collected from residential backyards, train trestle, near site grass patches and background areas varied from 1.144 to 1.196 for 206Pb/207Pb and 2.427 to 2.464 for 208Pb/207Pb. Two soil samples collected along Richmond Terrace, where Jewett site soils accumulated after major rain events, varied from 1.136 to 1.147 for 206Pb/207Pb and 2.407 to 2.419 for 208Pb/207Pb. Lead concentration for on-site surface soil samples ranged from 450 to 8000 ug/g, on-site subsurface soil samples ranged from 90,000 to 240,000 ug/g and off-site samples varied from 380 to 3500 ug/g. Lead concentration and isotopic composition for the Staten Island off-site samples were similar to previously published data for other northeastern US cities and reflect re-suspension and re-mobilization of local accumulated Pb. The considerable differences in both the Pb isotopic composition and Pb concentration of on-site and off-site samples resulted in the ability to geochemically trace the transport of particulate Pb. Data in this study indicate minimal off-site surface transport of Pb from the Jewett site into the neighboring residential area.

  11. An odyssey of environmental pollution: the rise, fall and remobilization of industrial lead in Australia

    NASA Astrophysics Data System (ADS)

    Taylor, M. P.; Kristensen, L.; Liqin, W.; Harvey, P. J.; Dong, C.; Rouillon, M.

    2015-12-01

    The use of lead in automobile gasoline resulted in more than 240,000 tonnes of lead being emitted to the Australian environment over its 70-year period of use starting in 1932. The consequences of the emissions and subsequent depositions have resulted in marked contamination of urban and peri-urban aerosols, soils, plants and humans. This paper charts these effects and examines the extent of recovery from one of the most pervasive and persistent environmental pollutants. Lead isotopic composition of Adelaide and Sydney aerosol filters show that air lead composition shifts from values that approximate Broken Hill type ores, the predominant lead source used in gasoline (1.04 206Pb/207Pb and 2.31 208Pb/207Pb), towards ratios that more closely match local uncontaminated soil and bedrock values (Adelaide ~1.19 206Pb/207Pb and ~2.50 208Pb/207Pb; Sydney ~1.15 206Pb/207Pb and 2.48 208Pb/207Pb). Proxy atmospheric measurements from historic wine, lichen and fungi samples extending over 120 years show how both concentration and composition values shifted in the middle to late 20th century to reflect petrol emissions and then recovered rapidly at the end of the century as leaded gasoline consumption declined. For example, lead in wine from South Australia fell from >100 μg/L in the 1960s and 1970s to < 5 μg/L in the 2010s due to the removal of the primary source of atmospheric lead - gasoline. However, measurement of contemporary surface soils, ash produced from wildfires and air filters demonstrate that the effect of depositions persists and industrial lead and other toxic metals (including arsenic, cadmium and nickel) are subject to frequent remobilization. Predicted increases in wildfires and the generation of lead, arsenic and cadmium toxic particulates warrants greater consideration of the risk for vulnerable populations and firefighters who are most exposed.

  12. Characteristics of lead geochemistry and the mobility of Pb isotopes in the system of pedogenic rock-pedosphere-irrigated riverwater-cereal-atmosphere from the Yangtze River delta region, China.

    PubMed

    Wang, Cheng; Wang, Jianhua; Yang, Zhongfang; Mao, Changping; Ji, Junfeng

    2013-11-01

    Knowledge of the characteristics of Pb and its isotopic transfer in different compartments is scant, especially for the mobility of Pb isotopes in the geochemical cycle. The present study characterizes differential Pb transport mechanism and the mobility of Pb isotopes in the pedogenic parent rock-pedosphere-irrigated riverwater-cereal-atmosphere system in the Yangtze River delta region, by determining Pb concentration and Pb isotopic ratios of pedogenic parent rocks, fluvial suspended particle matter, tillage soils, soil profiles, irrigated riverwater, fertilizer, Pb ore, cereal roots and grains. The results show that Pb isotopes in the geochemical cycle generally follow the equation of (208)Pb/(206)Pb=-1.157×(206)Pb/(207)Pb+3.46 (r(2)=0.941). However, Pb isotopes have different mobility in different environmental matrixes. Whereas in the pedosphere, the heavier Pb ((208)Pb) usually shows stronger mobility relative to the lighter Pb, and is more likely to transfer into soil exchangeable Pb fraction and carbonates phase. The lighter Pb shows stronger transfer ability from soil to cereal grain via root compared to the heavier Pb. However, the cereal grains have lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratios than root and tillage soil, similar to the airborne Pb and anthropogenic Pb, implying that a considerable amount of Pb in cereal grains comes from the atmosphere. The estimate model shows that 16.7-52.6% (average: 33.5%) of Pb in rice grain is the airborne Pb.

  13. The effect of shell closure on the thermodynamic properties of 207Pb and 89Y

    NASA Astrophysics Data System (ADS)

    Dehghani, V.; Forozani, Gh.; Benam, Kh.

    2016-11-01

    Nuclear level densities of 207Pb and 89Y are calculated using the Lipkin-Nogami (LN) method and Bradeen-Cooper-Schrieffer (BCS) model. It is revealed that the calculated nuclear level densities are highly matched with the experimental data of Oslo group. The excitation energy and entropy are calculated for mentioned nuclei. In the case of two studied nuclei the characteristic of being magic for the number of neutrons or protons causes the decrease of the excitation energy and entropy contribution of magic system at low temperatures.

  14. Trace element and Pb isotope composition of plagioclase from dome samples from the 2004-2005 eruption of Mount St. Helens, Washington: Chapter 35 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Kent, Adam J.R.; Rowe, Michael C.; Thornber, Carl R.; Pallister, John S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Plagioclase crystals from gabbronorite inclusions in three dacite samples have markedly different trace-element and Pbisotope compositions from those of plagioclase phenocrysts, despite having a similar range of anorthite contents. Inclusions show some systematic differences from each other but typically have higher Ti, Ba, LREE, and Pb and lower Sr and have lower 208Pb/206Pb and 207Pb/206Pb ratios than coexisting plagioclase phenocrysts. The compositions of plagioclase from inclusions cannot be related to phenocryst compositions by any reasonable petrologic model. From this we suggest that they are unlikely to represent magmatic cumulates or restite inclusions but instead are samples of mafic Tertiary basement from beneath the volcano.

  15. Concerning advantages in using 208Pb as such a FR coolant

    NASA Astrophysics Data System (ADS)

    Khorasanov, G.; Zemskov, E.; Blokhin, A.

    2017-01-01

    In the paper cores of two fast reactors with heavy liquid metal coolant are considered. The first object, RBETS-M, is a project of a medium power, 900 MW, reactor cooled with lead-bismuth. The second object, BRUTS, is a project of an ultra-small power, 0.5 MW, reactor cooled with lead. The results of replacement of their standard coolants with the lead coolant enriched up to 100% with 208Pb are presented. In the RBETS-M core having a large coolant volume share this replacement results in sufficient increasing the share of 238U involved in the fission process and respective decreasing the share of 239Pu and 241Pu burning.

  16. Light charged particles emitted in fission reactions induced by protons on 208Pb

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Paradela, C.; Ayyad, Y.; Casarejos, E.; Alvarez-Pol, H.; Audouin, L.; Bélier, G.; Boutoux, G.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelić-Heil, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.; Pietras, B.; Ramos, D.; Rodríguez-Tajes, C.; Rossi, D. M.; Simon, H.; Taïeb, J.; Vargas, J.; Voss, B.

    2016-09-01

    Light charged particles emitted in proton-induced fission reactions on 208Pb have been measured at different kinetic energies: 370 A ,500 A , and 650 A MeV. The experiment was performed by the SOFIA Collaboration at the GSI facilities in Darmstadt (Germany). The inverse kinematics technique was combined with a setup especially designed to measure light charged particles in coincidence with fission fragments. This measurement allowed us, for the first time, to obtain correlations between the light charged particles emitted during the fission process and the charge distributions of the fission fragments. These correlations were compared with different model calculations to assess the ground-to-saddle dynamics. The results confirm that transient and dissipative effects are required for an accurate description of the fission observables.

  17. Search for deeply bound pionic states in 208Pb via radiative atomic capture of negative pions

    NASA Astrophysics Data System (ADS)

    Raywood, K. J.; Lange, J. B.; Jones, G.; Pavan, M.; Sevior, M. E.; Hutcheon, D. A.; Olin, A.; Ottewell, D.; Yen, S.; Lee, S. J.; Sim, K. S.; Altman, A.; Friedman, E.; Trudel, A.

    1997-05-01

    A search for narrow, deeply bound pionic atom states via atomic radiative capture of negative pions in a target of 208Pb was carried out for pion kinetic energies of 20 and 25 MeV. Although no clear signature of any such gamma ray emission could be observed in the data, fits of the gamma ray spectra between the energies of 12 and 42 MeV involving a quadratic background together with a pair of peaks (1s, 2p) whose relative intensity was taken from theory yielded an overall strength for the peaks which are consistent (to a 67% confidence level) with radiative capture whose integrated cross section is 20.0 +/- 10.0 μb/sr at 90° for 20 MeV incident pions. A lower probability (40% confidence level) result was obtained when the fit was carried out without the peaks included, just the continuum background.

  18. Observation of Superheavy Nuclei Produced in the Reaction of 86Kr with 208Pb

    NASA Astrophysics Data System (ADS)

    Ninov, V.; Gregorich, K. E.; Loveland, W.; Ghiorso, A.; Hoffman, D. C.; Lee, D. M.; Nitsche, H.; Swiatecki, W. J.; Kirbach, U. W.; Laue, C. A.; Adams, J. L.; Patin, J. B.; Shaughnessy, D. A.; Strellis, D. A.; Wilk, P. A.

    1999-08-01

    Following a prediction by Smolan´czuk [Phys. Rev. C 59, 2634 (1999)], we searched for superheavy element formation in the bombardment of 208Pb with 449-MeV 86Kr ions. We have observed three decay chains, each consisting of an implanted heavy atom and six subsequent α decays, correlated in time and position. In these decay chains, a rapid (ms) sequence of high energy α particles ( Eα>=10 MeV) indicates the decay of a new high- Z element. The observed chains are consistent with the formation of 293118 and its decay by sequential α-particle emission to 289116, 285114, 281112, 277110, 273Hs ( Z = 108) and 269Sg ( Z = 106). The production cross section is 2.2+2.6-0.8 pb.

  19. Power of two: Assessing the impact of a second measurement of the weak-charge form factor of 208Pb

    NASA Astrophysics Data System (ADS)

    Piekarewicz, J.; Linero, A. R.; Giuliani, P.; Chicken, E.

    2016-09-01

    Background: Besides its intrinsic value as a fundamental nuclear-structure observable, the weak-charge density of 208Pb—a quantity that is closely related to its neutron distribution—is of fundamental importance in constraining the equation of state of neutron-rich matter. Purpose: To assess the impact that a second electroweak measurement of the weak-charge form factor of 208Pb may have on the determination of its overall weak-charge density. Methods: Using the two putative experimental values of the form factor, together with a simple implementation of Bayes' theorem, we calibrate a theoretically sound—yet surprisingly little known—symmetrized Fermi function, that is characterized by a density and form factor that are both known exactly in closed form. Results: Using the charge form factor of 208Pb as a proxy for its weak-charge form factor, we demonstrate that using only two experimental points to calibrate the symmetrized Fermi function is sufficient to accurately reproduce the experimental charge form factor over a significant range of momentum transfers. Conclusions: It is demonstrated that a second measurement of the weak-charge form factor of 208Pb supplemented by a robust theoretical input in the form of the symmetrized Fermi function would place significant constraints on the neutron distribution of 208Pb. In turn, such constraints will become vital in the interpretation of hadronic experiments that will probe the neutron-rich skin of exotic nuclei at future radioactive beam facilities.

  20. Complete dipole response in {sup 208}Pb from high-resolution polarized proton scattering at 0 deg

    SciTech Connect

    Neumann-Cosel, P. von; Kalmykov, Y.; Poltoratska, I.; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Adachi, T.; Fujita, Y.; Matsubara, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Bertulani, C. A.; Carter, J.; Fujita, H.; Dozono, M.; Fujita, K.; Hashimoto, H.; Hatanaka, K.

    2009-01-28

    The structure of electric and magnetic dipole modes in {sup 208}Pb is investigated in a high-resolution measurement of the (p-vector,p-vector') reaction under 0 deg. First results on the E1 strength in the region of the pygmy dipole resonance are reported.

  1. Evaporation residue cross-section in the decay of 254No* formed in 206Pb + 48Ca and its isotopic dependence using other Pb targets within the dynamical cluster-decay model

    NASA Astrophysics Data System (ADS)

    Niyti; Gupta, Raj K.; Hess, Peter Otto

    2015-06-01

    The dynamical cluster-decay model (DCM), with deformation and orientation effects included, is used to calculate the fusion evaporation residue cross-sections σxn for x = 1, 2, 3 and 4 neutrons emission in a fusion reaction 206Pb + 48Ca → 254No* at various 48Ca-beam energies Elab = 212.7- 242.5 MeV (equivalently, E* = 19.8- 43.9 MeV). Considering the higher multipole deformations up to hexadecapole deformation β4i and the sticking moment-of-inertia IS, the DCM with pocket formula for nuclear proximity potential is shown to give a good description of the measured individual light-particle (here neutrons) decay channels for configurations of "hot, compact" orientations θci, within one parameter fitting of the neck-length ΔR. A check on some of the variables involved in DCM shows that (i) spherical configurations give nearly the same result as above for deformed and oriented ones; (ii) the non-sticking moment-of-inertia INS gives unphysical results; and (iii) configurations of "cold, elongated" orientations do not fit the data at all. Furthermore, for the four different isotopes of 204,206,207,208Pb-based reactions, the dependence of, say, the 2n-emission yield σ2n on the isotopic composition of the compound nucleus is also studied within the DCM for "hot" fusion process. Of all the four Pb-isotopes and three excitation energies E* considered, at each E*, the ΔR is largest for compound system 256No*, followed by 255No*, 254No* and smallest for 252No*, which means to suggest that the neutrons emission occur earliest for 256No*, then for 255No*, 254No* and finally by 252No*, in complete agreement with experimental data according to which compound system 256No* has the highest cross-section and 252No* the lowest with 255No* and 254No* lying in between. This result is related to the double magicity of both the target (208Pb) and projectile (48Ca) nuclei, as well as to the experimentally known result of projectile with a larger number of neutrons (here the target

  2. A lead isotopic study of the human bioaccessibility of lead in urban soils from Glasgow, Scotland.

    PubMed

    Farmer, John G; Broadway, Andrew; Cave, Mark R; Wragg, Joanna; Fordyce, Fiona M; Graham, Margaret C; Ngwenya, Bryne T; Bewley, Richard J F

    2011-11-01

    The human bioaccessibility of lead (Pb) in Pb-contaminated soils from the Glasgow area was determined by the Unified Bioaccessibility Research Group of Europe (BARGE) Method (UBM), an in vitro physiologically based extraction scheme that mimics the chemical environment of the human gastrointestinal system and contains both stomach and intestine compartments. For 27 soils ranging in total Pb concentration from 126 to 2160 mg kg(-1) (median 539 mg kg(-1)), bioaccessibility as determined by the 'stomach' simulation (pH ~1.5) was 46-1580 mg kg(-1), equivalent to 23-77% (mean 52%) of soil total Pb concentration. The corresponding bioaccessibility data for the 'stomach+intestine' simulation (pH ~6.3) were 6-623 mg kg(-1) and 2-42% (mean 22%) of soil Pb concentration. The soil (206)Pb/(207)Pb ratios ranged from 1.057 to 1.175. Three-isotope plots of (208)Pb/(206)Pb against (206)Pb/(207)Pb demonstrated that (206)Pb/(207)Pb ratios were intermediate between values for source end-member extremes of imported Australian Pb ore (1.04)--used in the manufacture of alkyl Pb compounds (1.06-1.10) formerly added to petrol--and indigenous Pb ores/coal (1.17-1.19). The (206)Pb/(207)Pb ratios of the UBM 'stomach' extracts were similar (<0.01 difference) to those of the soil for 26 of the 27 samples (r=0.993, p<0.001) and lower in 24 of them. A slight preference for lower (206)Pb/(207)Pb ratio was discernible in the UBM. However, the source of Pb appeared to be less important in determining the extent of UBM-bioaccessible Pb than the overall soil total Pb concentration and the soil phases with which the Pb was associated. The significant phases identified in a subset of samples were carbonates, manganese oxides, iron-aluminium oxyhydroxides and clays.

  3. Single-particle parity-nonconserving matrix elements in {sup 207}Pb

    SciTech Connect

    Komives, A.; Knott, J.E.; Leuschner, M.; Szymanski, J.J.; Bowman, J.D.; Jamrisk, D.

    1993-10-01

    Measurements of the helicity dependence of neutron scattering off of heavy nuclei by the TRIPLE collaboration have yielded multiple parity-nonconserving asymmetries. The asymmetries are predominantly positive, in contradiction to the zero average asymmetry predicted by the statistical model of neutron- nucleus scattering. Theoretical calculations that explain the non-zero average asymmetry require single-particle parity- nonconserving matrix elements 10-100 times larger than those predicted by meson exchange models. We are determining the single-particle parity non-conserving mixing in {sup 207}Pb by measuring the circular polarization of the 1.064 MeV {gamma} ray. The experiment uses a transmission polarimeter and a fast data acquisition system. Initial results are presented.

  4. γ -ray spectroscopy of fission fragments produced in 208Pb(18O ,f )

    NASA Astrophysics Data System (ADS)

    Banerjee, P.; Ganguly, S.; Pradhan, M. K.; Moin Shaikh, Md.; Sharma, H. P.; Chakraborty, S.; Palit, R.; Pillay, R. G.; Nanal, V.; Saha, S.; Sethi, J.; Biswas, D. C.

    2015-08-01

    Prompt gamma-ray spectroscopy of fission fragments produced in the heavy-ion induced fusion-fission reaction 208Pb(18O,f ) at E =90 MeV has been performed. The relative isotopic yields of the fission fragments and the fragment mass distribution have been studied. Structures in the mass distribution have been discussed in the light of earlier results. Relative yields of several odd-A isotopes of Mo, Ru, Pd, and Cd and the odd-A isotones with N =62 and 64 have been studied along with the yields of the neighboring even-Z , even-N fragments and correlated to nuclear structural effects. The average total neutron multiplicity during fission has been measured to be 5.48 ±0.59 . The level schemes of the two neutron-rich nuclei 110Pd and 116Cd have been studied from γ -ray triple coincidence data. A large number of transitions, previously reported only from β -decay studies, have been observed in 110Pd for the first time. The yrast band in 116Cd has been extended up to spin (16+). In addition, a rotational sequence built upon an excited 5- state in 116Cd has been observed up to (13-). The level schemes have been discussed in the context of existing results, both experimental and theoretical, in the literature.

  5. Neutron-Rich Isotopes from 208Pb at 86 MeV/u

    NASA Astrophysics Data System (ADS)

    Tarasov, O. B.; Portillo, M.; Amthor, A. M.; Baumann, T.; Bazin, D.; Folden, C.; Ginter, T.; Hausmann, M.; Morrissey, D. J.; Pereira, J.; Sherrill, B. M.; Thoennessen, M.; Nociforo, C.

    2008-10-01

    An experiment to measure production yields from a beam of ^208Pb (86 MeV/u) on Be and Ni-targets has recently been performed. The A1900 fragment-separator [1] was used to analyze products from projectile fragmentation and abrasion-fission [2]. Isotopic identification of nuclides having A˜200 has been achieved, demonstrating that adequate A,Z,Q resolution at this energy region is possible when using silicon detectors. The verification of PID is done via detection of multiple charge state distributions of the primary beam, as well as γ-decay of known isomers with half-lives in the microsecond range. The results demonstrate that experiments with heavy nuclei are possible at the NSCL using beams of A>200. Production cross-sections have been extracted from the data that can help improve the accuracy of production models such as Abrasion-Ablation and Abrasion-Fission used in the LISE++ code [3]. The data reveal the existence of previously unreported isomeric transitions and further analysis is ongoing that may also lead to the observation of new isotopes. References: [1] D.J.Morrissey et al., Nucl. Instrum. Meth. B204 (2003) 90--96. [2] O.B. Tarasov, Tech. Rep. MSUCL1300, NSCL, Michigan St.Univ., 2005. [3] O.B. Tarasov, D. Bazin, Nucl. Phys. A 746 (2004) 411; www.nscl.msu.edu/lise .

  6. Hindrance of complete fusion in the {sup 8}Li+{sup 208}Pb system at above-barrier energies

    SciTech Connect

    Aguilera, E. F.; Martinez-Quiroz, E.; Rosales, P.; Kolata, J. J.; DeYoung, P. A.; Peaslee, G. F.; Mears, P.; Guess, C.; Becchetti, F. D.; Lupton, J. H.; Chen, Yu

    2009-10-15

    The {sup 211,212}At yields resulting from the interaction of the radioactive projectile {sup 8}Li with a {sup 208}Pb target have been measured at energies between 3 and 8.5 MeV above the Coulomb barrier. They are signatures for fusion of the whole charge but not necessarily the whole mass of the projectile, so they are included in a corresponding operational definition of complete fusion. Within this definition, a fusion suppression factor of 0.70{+-}0.02 (stat.) {+-}0.04 (syst.) is deduced from a comparison to a one-dimensional barrier-penetration-model calculation using parameters extrapolated from values for {sup 6,7}Li+{sup 209}Bi and {sup 9}Be+{sup 208}Pb taken from the literature. Possible incomplete fusion processes are discussed and the results are fitted with a phenomenological model assuming breakup prior to fusion followed by capture of a {sup 7}Li fragment.

  7. Complete dipole strength distributions in 208Pb from high-resolution polarized proton scattering at 0°

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, Peter

    2012-02-01

    Small-angle polarized proton scattering including 0° at incident energies of a few 100 MeV/nucleon is established as a new spectrospcopic tool for the study of E1 and M1 strength distributions. Experiments of this type have been realized recently at RCNP, Osaka, Japan with high energy resolution of the order 25 - 30 keV (FWHM). Using 208Pb as an example, the physics potential of such data is discussed. It includes information on the properties of the Pygmy Dipole Resonance but also on complete E1 and M1 strength distributions and thus the gamma strength function. The E1 polarizability can be extracted with a precision of about 4% providing important experimental constraints on the neutron skin thickness in 208Pb.

  8. Measurement of the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg excitation function

    SciTech Connect

    Folden III, C. M.; Dragojevic, I.; Garcia, M. A.; Gates, J. M.; Nelson, S. L.; Hoffman, D. C.; Nitsche, H.; Duellmann, Ch. E.; Sudowe, R.; Gregorich, K. E.; Eichler, R.

    2009-02-15

    The excitation function for the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of 320{sub -100}{sup +110} pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from {sup 259}Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the {sup 208}Pb({sup 52}Cr,2n){sup 258}Sg reaction was obtained, and an improved {sup 258}Sg half-life of 2.6{sub -0.4}{sup +0.6} ms was calculated by combining all available experimental data.

  9. Isospin character of low-lying pygmy dipole states in 208Pb via inelastic scattering of 17O ions.

    PubMed

    Crespi, F C L; Bracco, A; Nicolini, R; Mengoni, D; Pellegri, L; Lanza, E G; Leoni, S; Maj, A; Kmiecik, M; Avigo, R; Benzoni, G; Blasi, N; Boiano, C; Bottoni, S; Brambilla, S; Camera, F; Ceruti, S; Giaz, A; Million, B; Morales, A I; Vandone, V; Wieland, O; Bednarczyk, P; Ciemała, M; Grebosz, J; Krzysiek, M; Mazurek, K; Zieblinski, M; Bazzacco, D; Bellato, M; Birkenbach, B; Bortolato, D; Calore, E; Cederwall, B; Charles, L; de Angelis, G; Désesquelles, P; Eberth, J; Farnea, E; Gadea, A; Görgen, A; Gottardo, A; Isocrate, R; Jolie, J; Jungclaus, A; Karkour, N; Korten, W; Menegazzo, R; Michelagnoli, C; Molini, P; Napoli, D R; Pullia, A; Recchia, F; Reiter, P; Rosso, D; Sahin, E; Salsac, M D; Siebeck, B; Siem, S; Simpson, J; Söderström, P-A; Stezowski, O; Theisen, Ch; Ur, C; Valiente-Dobón, J J

    2014-07-04

    The properties of pygmy dipole states in 208Pb were investigated using the 208Pb(17O, 17O'γ) reaction at 340 MeV and measuring the γ decay with high resolution with the AGATA demonstrator array. Cross sections and angular distributions of the emitted γ rays and of the scattered particles were measured. The results are compared with (γ, γ') and (p, p') data. The data analysis with the distorted wave Born approximation approach gives a good description of the elastic scattering and of the inelastic excitation of the 2+ and 3- states. For the dipole transitions a form factor obtained by folding a microscopically calculated transition density was used for the first time. This has allowed us to extract the isoscalar component of the 1- excited states from 4 to 8 MeV.

  10. Total fission cross section of {sup 181}Ta and {sup 208}Pb induced by protons at relativistic energies

    SciTech Connect

    Ayyad, Y.; Benlliure, J.; Casarejos, E.; Schmidt, K. H.; Jurado, B.; Pol, H. A.; Ricciardi, M. V.; Pleskac, R.; Enqvist, T.; Rejmund, F.; Giot, L.; Henzl, V.; Lukic, S.; Ngoc, S. N.; Boudard, A.; Leray, S.; Kurtukian, T.; Schmitt, C.; Henzlova, D.; Paradela, C.; Bacquias, A.; Loureiro, D. P.; Foehr, V.; Tarrio, D.; Kezzar, K.

    2011-07-01

    Total fission cross section induced by protons in {sup 181}Ta and {sup 208}Pb at energies in the range of 300 to 1000 A MeV have been measured at GSI (Germany) using the inverse kinematics technique. A dedicated setup with high efficiency made it possible to determine these cross sections with high accuracy. The new data seed light in the controversial results obtained so far and contribute to the understanding of the fission process at high excitation energies. (authors)

  11. Flux rates of atmospheric lead pollution within soils of a small catchment in northern Sweden and their implications for future stream water quality.

    PubMed

    Klaminder, Jonatan; Bindler, Richard; Laudon, Hjalmar; Bishop, Kevin; Emteryd, Ove; Renberg, Ingemar

    2006-08-01

    It is not well-known how the accumulated pool of atmospheric lead pollution in the boreal forest soil will affect the groundwater and surface water chemistry in the future as this lead migrates through the soil profile. This study uses stable lead isotopes (206Pb/207Pb and 208Pb/ 207Pb ratios) to trace the transport of atmospheric lead pollution within the soil of a small catchment and predict future lead level changes in a stream draining the catchment. Low 206Pb/207Pb and 208Pb/207Pb ratios for the lead in the soil water (1.16 +/- 0.02; 2.43 +/- 0.03) and streamwater (1.18 +/- 0.03; 2.42 +/- 0.03) in comparison to that of the mineral soil (>1.4; >2.5) suggest that atmospheric pollution contributes by about 90% (65-100%) to the lead pool found in these matrixes. Calculated transport rates of atmospheric lead along a soil transect indicate that the mean residence time of lead in organic and mineral soil layers is at a centennial to millennial time scale. A maximum release of the present pool of lead pollution in the soil to the stream is predicted to occur within 200-800 years. Even though the uncertainty of the prediction is large, it emphasizes the magnitude of the time lag between the accumulation of atmospheric lead pollution in soils and the subsequent response in streamwater quality.

  12. Tracing changes in atmospheric sources of lead contamination using lead isotopic compositions in Australian red wine.

    PubMed

    Kristensen, Louise Jane; Taylor, Mark Patrick; Evans, Andrew James

    2016-07-01

    Air quality data detailing changes to atmospheric composition from Australia's leaded petrol consumption is spatially and temporally limited. In order to address this data gap, wine was investigated as a potential proxy for atmospheric lead conditions. Wine spanning sixty years was collected from two wine regions proximal to the South Australian capital city, Adelaide, and analysed for lead concentration and lead and strontium isotopic composition for source apportionment. Maximum wine lead concentrations (328 μg/L) occur prior to the lead-in-air monitoring in South Australia in the later 1970s. Wine lead concentrations mirror available lead-in-air measurements and show a declining trend reflecting parallel reductions in leaded petrol emissions. Lead from petrol dominated the lead in wine ((206)Pb/(207)Pb: 1.086; (208)Pb/(207)Pb: 2.360) until the introduction of unleaded petrol, which resulted in a shift in the wine lead isotopic composition closer to vineyard soil ((206)Pb/(207)Pb: 1.137; (208)Pb/(207)Pb: 2.421). Current mining activities or vinification processes appear to have no impact with recent wine samples containing less than 4 μg/L of lead. This study demonstrates wine can be used to chronicle changes in environmental lead emissions and is an effective proxy for atmospherically sourced depositions of lead in the absence of air quality data.

  13. γ strength function and level density of 208Pb from forward-angle proton scattering at 295 MeV

    NASA Astrophysics Data System (ADS)

    Bassauer, S.; von Neumann-Cosel, P.; Tamii, A.

    2016-11-01

    Background: γ strength functions (GSFs) and level densities (LDs) are essential ingredients of statistical nuclear reaction theory with many applications in astrophysics, reactor design, and waste transmutation. Purpose: The aim of the present work is a test of systematic parametrizations of the GSF recommended by the RIPL-3 database for the case of 208Pb. The upward GSF and LD in 208Pb are compared to γ decay data from an Oslo-type experiment to examine the validity of the Brink-Axel (BA) hypothesis. Methods: The E 1 and M1 parts of the total GSF are determined from high-resolution forward angle inelastic proton scattering data taken at 295 MeV at the Research Center for Nuclear Physics (RCNP), Osaka, Japan. The total LD in 208Pb is derived from the 1- LD extracted with a fluctuation analysis in the energy region of the isovector giant dipole resonance. Results: The E 1 GSF is compared to parametrizations recommended by the RIPL-3 database showing systematic deficiencies of all models in the energy region around neutron threshold. The new data for the poorly known spin-flip M 1 resonance call for a substantial revision of the model suggested in RIPL-3. The total GSF derived from the present data is larger in the PDR energy region than the Oslo data but the strong fluctuations due to the low LD resulting from the double shell closure of 208Pb prevent a conclusion on a possible violation of the BA hypothesis. Using the parameters suggested by RIPL-3 for a description of the LD in 208Pb with the back-shifted Fermi gas model, remarkable agreement between the two experiments spanning a wide excitation energy range is obtained. Conclusions: Systematic parametrizations of the E 1 and M 1 GSF parts need to be reconsidered at low excitation energies. The good agreement of the LD provides an independent confirmation of the approach underlying the decomposition of GSF and LD in Oslo-type experiments.

  14. Weak charge form factor and radius of 208Pb through parity violation in electron scattering

    DOE PAGES

    Horowitz, C. J.; Ahmed, Z.; Jen, C. -M.; ...

    2012-03-26

    We use distorted wave electron scattering calculations to extract the weak charge form factor FW(more » $$\\bar{q}$$), the weak charge radius RW, and the point neutron radius Rn, of 208Pb from the PREX parity violating asymmetry measurement. The form factor is the Fourier transform of the weak charge density at the average momentum transfer $$\\bar{q}$$ = 0.475 fm-1. We find FW($$\\bar{q}$$) = 0.204 ± 0.028(exp) ± 0.001(model). We use the Helm model to infer the weak radius from FW($$\\bar{q}$$). We find RW = 5.826 ± 0.181(exp) ± 0.027(model) fm. Here the exp error includes PREX statistical and systematic errors, while the model error describes the uncertainty in RW from uncertainties in the surface thickness σ of the weak charge density. The weak radius is larger than the charge radius, implying a 'weak charge skin' where the surface region is relatively enriched in weak charges compared to (electromagnetic) charges. We extract the point neutron radius Rn = 5.751 ± 0.175 (exp) ± 0.026(model) ± 0.005(strange) fm, from RW. Here there is only a very small error (strange) from possible strange quark contributions. We find Rn to be slightly smaller than RW because of the nucleon's size. As a result, we find a neutron skin thickness of Rn-Rp = 0.302 ± 0.175 (exp) ± 0.026 (model) ± 0.005 (strange) fm, where Rp is the point proton radius.« less

  15. Dipole response in 208Pb within a self-consistent multiphonon approach

    NASA Astrophysics Data System (ADS)

    Knapp, F.; Lo Iudice, N.; Veselý, P.; Andreozzi, F.; De Gregorio, G.; Porrino, A.

    2015-11-01

    Background: The electric dipole strength detected around the particle threshold and commonly associated with the pygmy dipole resonance offers unique information on neutron skin and symmetry energy, and is of astrophysical interest. The nature of such a resonance is still under debate. Purpose: We intend to describe the giant and pygmy resonances in 208Pb by enhancing their fragmentation with respect to the random-phase approximation. Method: We adopt the equation of motion phonon method to perform a fully self-consistent calculation in a space spanned by one-phonon and two-phonon basis states using an optimized chiral two-body potential. A phenomenological density-dependent term, derived from a contact three-body force, is added to get single-particle spectra more realistic than the ones obtained by using the chiral potential only. The calculation takes into full account the Pauli principle and is free of spurious center-of-mass admixtures. Results: We obtain a fair description of the giant resonance and obtain a dense low-lying spectrum in qualitative agreement with the experimental data. The transition densities as well as the phonon and particle-hole composition of the most strongly excited states support the pygmy nature of the low-lying resonance. Finally, we obtain realistic values for the dipole polarizability and the neutron skin radius. Conclusions: The results emphasize the role of the two-phonon states in enhancing the fragmentation of the strength in the giant resonance region and at low energy, consistently with experiments. For a more detailed agreement with the data, the calculation suggests the inclusion of the three-phonon states as well as a fine tuning of the single-particle spectrum to be obtained by a refinement of the nuclear potential.

  16. Age of the moon: An isotopic study of uranium-thorium-lead systematics of lunar samples

    USGS Publications Warehouse

    Tatsumoto, M.; Rosholt, J.N.

    1970-01-01

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of 207Pb/206Pb, 206Pb/238U, 207Pb/235U, and 208Pb/232Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The 238U/235U ratio is the same as that in earth rocks, and 234U is in radioactive equilibrium with parent 238U.

  17. Age of the moon: an isotopic study of uranium-thorium-lead systematics of lunar samples.

    PubMed

    Tatsumoto, M; Rosholt, J N

    1970-01-30

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of (207)Pb/(206)Pb, (206)Pb/(238)U, (207)Pb/(235U), and(208)Pb/(232)Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The (238)U/(235)U ratio is the same as that in earth rocks, and (234)U is in radioactive equilibrium with parent (238)U.

  18. DNP-enhanced ultrawideline (207)Pb solid-state NMR spectroscopy: an application to cultural heritage science.

    PubMed

    Kobayashi, Takeshi; Perras, Frédéric A; Murphy, Anna; Yao, Yao; Catalano, Jaclyn; Centeno, Silvia A; Dybowski, Cecil; Zumbulyadis, Nicholas; Pruski, Marek

    2017-03-14

    Dynamic nuclear polarization (DNP) is used to enhance the (ultra)wideline (207)Pb solid-state NMR spectra of lead compounds of relevance in the preservation of cultural heritage objects. The DNP SSNMR experiments enabled, for the first time, the detection of the basic lead carbonate phase of the lead white pigment by (207)Pb SSNMR spectroscopy. Variable-temperature experiments revealed that the short T'2 relaxation time of the basic lead carbonate phase hinders the acquisition of the NMR signal at room temperature. We additionally observe that the DNP enhancement is twice as large for lead palmitate (a lead soap, which is a degradation product implicated in the visible deterioration of lead-based oil paintings), than it is for the basic lead carbonate. This enhancement has allowed us to detect the formation of a lead soap in an aged paint film by (207)Pb SSNMR spectroscopy; which may aid in the detection of deterioration products in smaller samples removed from works of art.

  19. Isotopic source signatures for atmospheric lead: the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Bollhöfer, A.; Rosman, K. J. R.

    2000-10-01

    Aerosols collected between 1994 and 1999 at more than 70 different sites affecting the Southern Hemisphere have been measured for their 206Pb/ 207Pb, 208Pb/ 207Pb and 206Pb/ 204Pb ratios and Pb concentrations. Lower ratios are found at the southern tips of Africa, Australia and South America probably due to the supply of alkyllead from a common supplier such as Associated Octel. The ratios increase in a northerly direction probably due to a changing market share in alkyllead or an increasing industrial Pb contribution. The geographical variations in isotopic signatures made it possible to broadly characterize the different regions that influence the Southern Hemisphere. Brazil and Argentina exhibited 206Pb/ 207Pb, 208Pb/ 207Pb and 206Pb/ 204Pb ratios in aerosols of 1.141-1.184, 2.416-2.442 and 17.77-18.57, respectively. Mexican aerosols had values of 1.188-1.197, 2.452-2.463 and 18.46-18.73. Aerosols sampled in Chile had low ratios in the South of 1.063-1.094, 2.337-2.373 and 16.46-17.13 which increased in a northerly direction. Emissions from South Africa were characterized by ratios 1.067-1.090, 2.340-2.358 and 16.53-16.99. In 1994-1995 Australia and New Zealand had ratios of 1.060-1.193, 2.324-2.445 and 16.08-18.54. In 1997 however, the range was narrower: 1.072-1.112, 2.342-2.398 and 16.55-17.36, respectively. These isotopic signatures are potentially useful for tracing sources of pollution and the movement of air-masses on a global scale.

  20. A comparison of the isotopic composition of lead in rainwater, surface vegetation and tree bark at the long-term monitoring site, Glensaugh, Scotland, in 2007.

    PubMed

    Farmer, John G; Eades, Lorna J; Graham, Margaret C; Cloy, Joanna M; Bacon, Jeffrey R

    2010-08-01

    The lead concentrations and isotopic ratios (206Pb/207Pb, 208Pb/206Pb, 208Pb/207Pb) of 31 rainwater (September 2006-December 2007) and 11 surface vegetation (moss, lichen, heather) samples (October 2007) from the rural upland catchment of Glensaugh in northeast Scotland and of nine bark samples (October 2007) from trees, predominantly Scots pine, in or near Glensaugh were determined. The mean 206Pb/207Pb ratios for rainwater in 2006 and 2007 were similar to those previously determined for 2000 to 2003 at Glensaugh, yielding an average mean annual value of 1.151+/-0.005 (+/-1 SD) for the period from 2000, when an outright ban on leaded petrol came into force in the UK, to 2007. The mean 206Pb/207Pb ratio (1.146+/-0.004; n=7) for surface vegetation near the top (430-450 m) of the catchment was not significantly different (Student's t test) from that of rainwater (1.148+/-0.017; n=24) collected over the 12-month period prior to vegetation sampling, but both were significantly different, at the 0.1% (i.e. p<0.001) and 1% (p<0.01) level, respectively, from the corresponding mean value (1.134+/-0.006; n=9) for the outermost layer of tree bark. When considered in conjunction with similar direct evidence for 2002 and indirect evidence (e.g. grass, atmospheric particulates, dated peat) for recent decades in the Glensaugh area, these findings confirm that the lead isotopic composition of surface vegetation, including that of suitably located moss, reflects that of the atmosphere while that of the outermost layer of Scots pine bark is affected by non-contemporaneous lead. The nature and relative extent of the different contributory sources of lead to the current UK atmosphere in the era of unleaded petrol, however, are presently not well characterised on the basis of lead isotopic measurements.

  1. Dendrochemical record of historical lead contamination sources, Wells G&H Superfund site, Woburn, Massachusetts.

    PubMed

    Burnett, Aaron; Kurtz, Andrew C; Brabander, Daniel; Shailer, Mark

    2007-01-01

    Laser-ablation inductively coupled-plasma mass-spectrometry analysis of red oak (Quercus rubra) from a well documented heavy metal contaminated United States Environmental Protection Agency superfund site in Woburn, Massachusetts reveals decade-long trends in Pb contaminant sources. Lead isotope ratios (207Pb/206Pb and 208Pb/206Pb) in tree rings plot along a linear trend bracketed by several local and regional contamination sources. Statistically significant interannual variations in 207Pb/206Pb suggest that atmospheric Pb is rapidly incorporated into wood, with minimal mobility subsequent to deposition in annual growth rings. We interpret the decadal trends in our record as a changing mixture of local pollution sources and gasoline-derived Pb. Between 1940 and 1970, Pb was predominantly derived from remobilization of local industrial Pb sources. An abrupt shift in 207Pb/206Pb may indicate that local Pb sources were overwhelmed by gasoline-derived Pb during the peak of leaded gasoline emissions in the late 1960s and early 1970s.

  2. Pionic fusion near threshold using the /sup 208/Pb(/sup 3/He,. pi. /sup -/)/sup 211/At reaction

    SciTech Connect

    Ward, T.E.

    1987-12-01

    The coherent production of pions in the /sup 208/Pb(/sup 3/He,..pi../sup -/)/sup 211/At reaction was measured radiochemically using activation techniques near the physical pion threshold at energies of 158--270 MeV. Above threshold, the total cross sections were measured in the 1--10 nb range. A theoretical fit of the summed total cross section into all particle bound states was made using the two-nucleon model of Dillig with appropriate two-body scaling of the momentum transfer.

  3. Study of the γ decay of high-lying states in 208Pb via inelastic scattering of 17O ions

    NASA Astrophysics Data System (ADS)

    Crespi, F. C. L.; Kmiecik, M.; Bracco, A.; Leoni, S.; Maj, A.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Ceruti, S.; Giaz, A.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Riboldi, S.; Vandone, V.; Wieland, O.; Bednarczyk, P.; Ciemala, M.; Grebosz, J.; Krzysiek, M.; Mazurek, K.; Zieblinski, M.; Bazzacco, D.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Calore, E.; De Angelis, G.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Isocrate, R.; Lenzi, S.; Lunardi, S.; Mengoni, D.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Recchia, F.; Sahin, E.; Siebeck, B.; Siem, S.; Ur, C.; Valiente Dobon, J. J.

    2014-03-01

    A measurement of the high-lying states in 208Pb has been made using 17O beams at 20 MeV/u. The gamma decay following inelastic excitation was measured with the detector system AGATA Demonstrator based on segmented HPGe detectors, coupled to an array of large volume LaBr3:Ce scintillators and to an array of Si detectors. Preliminary results in comparison with (γ,γ') data, for states in the 5-8 MeV energy interval, are presented.

  4. Response function of the magnetic spectrometer PRISMA for the multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb

    SciTech Connect

    Mijatovic, T.; Szilner, S.; Corradi, L.; Courtin, S.; Farnea, E.; Fioretto, E.; Gadea, A.; Goasduff, A.; Haas, F.; Jelavic-Malenica, D.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Montanari, D.; Pollarolo, G.; Recchia, F.; Sahin, E.; Scarlassara, F.; Soic, N.; Stefanini, A. M.; and others

    2012-10-20

    Multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb has been investigated with the PRISMA-CLARA experimental setup in LNL, INFN, Italy. The experimental differential cross sections have been obtained for different transfer channels by measuring more than {Delta}{theta}{sub lab} = 20 Degree-Sign covered by three angular settings of PRISMA. Results have been compared with the semiclassical calculation GRAZING. Since the understanding of the reaction mechanism depends strongly on the determination of absolute cross section, effect of transport of ions through PRISMA has been studied via a Monte Carlo simulation code.

  5. Nuclear spectroscopy study of the isotopes populated via multinucleon transfer in the 90Zr + 208Pb reaction

    SciTech Connect

    Ur, C. A.; Corradi, L.; Stefanini, A. M.; Behera, B. R.; Fioretto, E.; Gadea, A.; Latina, A.; Szilner, S.; Beghini, S.; Farnea, E.; Montagnoli, G.; Scarlassara, F.; Haas, F.; Pollarolo, G.

    2006-08-14

    The present work takes advantage of the multinucleon transfer mechanism between heavy reaction partners to study the population pattern of excited nuclear states in near spherical Zirconium isotopes following the 90Zr + 208Pb reaction at an energy closed to the Coulomb barrier. Both the projectile and the target are well known closed shell nuclei offering an optimum situation for clean experimental and theoretical conditions. Total kinetic energy loss (TKEL) distributions were compared with calculations performed with the GRAZING code. The ability to use the TKEL as a selection tool for the states at different excitation energies was shown.

  6. Levels and source apportionment of children's lead exposure: could urinary lead be used to identify the levels and sources of children's lead pollution?

    PubMed

    Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

    2015-04-01

    As a highly toxic heavy metal, the pollution and exposure risks of lead are of widespread concern for human health. However, the collection of blood samples for use as an indicator of lead pollution is not always feasible in most cohort or longitudinal studies, especially those involving children health. To evaluate the potential use of urinary lead as an indicator of exposure levels and source apportionment, accompanying with environmental media samples, lead concentrations and isotopic measurements (expressed as (207)Pb/(206)Pb, (208)Pb/(206)Pb and (204)Pb/(206)Pb) were investigated and compared between blood and urine from children living in the vicinities of a typical coking plant and lead-acid battery factory. The results showed urinary lead might not be a preferable proxy for estimating blood lead levels. Fortunately, urinary lead isotopic measurements could be used as an alternative for identifying the sources of children's lead exposure, which coincided well with the blood lead isotope ratio analysis.

  7. Solid-state 207Pb NMR studies of mixed lead halides, PbFX (X=Cl, Br, or I).

    PubMed

    Glatfelter, Alicia; Dybowski, Cecil; Kragten, David D; Bai, Shi; Perry, Dale L; Lockard, Jenny

    2007-04-01

    Solid-state 207Pb NMR studies have been conducted on mixed lead(II) halides of the type PbFX, where X=Cl, Br, or I. NMR data for the mixed halides are compared to the solid-state NMR data for the divalent, binary lead halides, PbX2 (X=F, Cl, Br, I). The NMR data are evaluated in the context of the structures of the compounds and the effects of the mixed halides on the electronic structure of the divalent lead. Data sets for the mixed halides are discussed and compared to those for the regular lead(II) halides.

  8. Lead shot contribution to blood lead of First Nations people: the use of lead isotopes to identify the source of exposure.

    PubMed

    Tsuji, Leonard J S; Wainman, Bruce C; Martin, Ian D; Sutherland, Celine; Weber, Jean-Philippe; Dumas, Pierre; Nieboer, Evert

    2008-11-01

    Although lead isotope ratios have been used to identify lead ammunition (lead shotshell pellets and bullets) as a source of exposure for First Nations people of Canada, the actual source of lead exposure needs to be further clarified. Whole blood samples for First Nations people of Ontario, Canada, were collected from participants prior to the traditional spring harvest of water birds, as well as post-harvest. Blood-lead levels and stable lead isotope ratios prior to, and after the harvest were determined by ICP-MS. Data were analyzed by paired t-tests and Wilcoxon Signed-Ranks tests. All participants consumed water birds harvested with lead shotshell during the period of study. For the group excluding six males who were potentially exposed to other sources of lead (as revealed through a questionnaire), paired t-tests and Wilcoxon Signed-Ranks tests showed consistent results: significant (p<0.05) increases in blood-lead concentrations and blood levels of (206)Pb/(204)Pb and (206)Pb/(207)Pb towards the mean values we previously reported for lead shotshell pellets; and a significant decrease in (208)Pb/(206)Pb values towards the mean for lead shotshell pellets. However, when we categorized the group further into a group that did not use firearms and did not eat any other traditional foods harvested with lead ammunition other than waterfowl, our predictions for (206)Pb/(204)Pb, (206)Pb/(207)Pb and (208)Pb/(206)Pb hold true, but there was not a significant increase in blood-lead level after the hunt. It appears that the activity of hunting (i.e., use of a shotgun) was also an important route of lead exposure. The banning of lead shotshell for all game hunting would eliminate a source of environmental lead for all people who use firearms and/or eat wild game.

  9. Metal enrichment and lead isotope analysis for source apportionment in the urban dust and rural surface soil.

    PubMed

    Yu, Yang; Li, Yingxia; Li, Ben; Shen, Zhenyao; Stenstrom, Michael K

    2016-09-01

    To understand the metal accumulation in the environment and identify its sources, 29 different metal contents and lead (Pb) isotope ratios were determined for 40 urban dust samples, 36 surface soil samples, and one river sediment sample collected in the municipality of Beijing, China. Results showed that cadmium, copper (Cu), mercury, Pb, antimony (Sb), and zinc demonstrated to be the typical urban contaminants and mostly influenced by the adjacent human activities with higher content to background ratios and SD values. Among the 29 metal elements investigated, Cu and Sb were found to be the most distinct elements that were highly affected by the developing level and congestion status of the cities with much higher contents in dust in more developed and congested cities. There was a relatively wider range of Pb isotope ratios of country surface soil than those of urban dust. The results of source identification based on Pb isotope ratios showed that coal combustion was the first largest Pb source and vehicle exhaust was the second largest source. The sum of them accounted for 74.6% mass proportion of overall Pb pollution on average. The surface soil sample collected at an iron mine had the highest (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios indicating ore had much higher ratios than other sources. The fine particle subsamples had higher (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios than the coarse particle subsamples indicating more anthropogenic sources of coal combustion and vehicle exhaust for fine particles and more background influence for coarse particles. These results help with pinpointing the major Pb sources and applying suitable measures for the target sources.

  10. Isotopic evolution of atmospheric Pb from metallurgical processing in Flin Flon, Manitoba: Retrospective analysis using peat cores from bogs.

    PubMed

    Shotyk, W; Rausch, N; Outridge, P M; Krachler, M

    2016-11-01

    Atmospheric Pb deposition was reconstructed using peat cores from bogs in the vicinity of Flin Flon, Manitoba, Canada, home to a zinc refinery and copper smelter. The Sask Lake (SL4-1) core was collected 85 km NW of Flin Flon and Kotyk Lake (KOL) 30 km NE. The distribution of Sr and U show that both profiles are predominantly minerotrophic (ie groundwater-fed), but the Pb concentration profile shows that Pb was received exclusively from the atmosphere. Graphs of (208)Pb/(206)Pb against (206)Pb/(207)Pb document atmospheric Pb contamination dating from the early to mid-1800's, well before the start of metallurgical processing (in 1930) and attributable to long-range atmospheric transport from other regions of North America. Industrial activities at Flin Flon clearly affected the concentrations, enrichment factor (calculated using Sc), and accumulation rates of Pb, but it is the similarity in isotopic composition, and contrast with crustal values ((206)Pb/(207)Pb ca. 1.20 to 1.22) which makes the connection to the Flin Flon ores. The KOL samples dating from 1925-1976 CE have a (206)Pb/(207)Pb of 1.032 ± 0.002 (n = 11) which approach the values for the Flin Flon ores ((206)Pb/(207)Pb = 1.008). But even at SL4-1, the peat samples dating from 1925-1976 CE have a (206)Pb/(207)Pb of 1.061 ± 0.022 (n = 18) which is well below the corresponding ratio of Canadian leaded gasoline ((206)Pb/(207)Pb = ca. 1.15). The SL4-1 site too, therefore, was clearly impacted by Pb from mining and metallurgy, despite the distance (88 km) from Flin Flon and being predominantly upwind. These two bogs not only provide the chronology of atmospheric Pb deposition for the past decades, but suggest that the extent of contamination may have been underestimated by previous studies.

  11. (. pi. sup +- ,. pi. sup +- prime N) reactions on sup 12 C and sup 208 Pb near the giant resonance region

    SciTech Connect

    Yoo, Sung Hoon.

    1990-05-01

    Angular distributions for the {sup 12}C({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p) and {sup 208}Pb({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p or n) reactions near the giant resonance region have been measured at T{sub {pi}} = 180 MeV, and found different between {pi}{sup +} and {pi}{sup {minus}} data. This observation is interpreted as evidence for different excitation mechanisms dominating the {pi}{sup {minus}}-nucleus and {pi}{sup +}-nucleus interactions in the giant resonance region of these targets. A comparison with the single-nucleon knock-out distorted-wave impulse approximation calculations shows, even though these calculations underestimate ({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} N) data for both targets, the dominance of direct process for ({pi}{sup +}, {pi}{sup {plus}}{prime} p) or ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} n) in contrast to ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) or ({pi}{sup +}, {pi}{sup +}{prime} n). In the ({pi}{sup +}, {pi}{sup +}{prime} p) reaction proton-proton hole states are excited directly and appear to have a large probability for direct decay with escape width, whereas in ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) the preferentially excited neutron-neutron hole doorway states couple to resonance states and decay with spreading width. This interpretation led us to suggest that the ratio of cross-sections for inelastic scattering to the giant resonance region should be written in terms of an incoherent sum of cross-sections to neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states contribute incoherently because the different decay processes do not populate the same final states of the residual nucleus.

  12. Multinucleon transfer in O,1816,19F+208Pb reactions at energies near the fusion barrier

    NASA Astrophysics Data System (ADS)

    Rafferty, D. C.; Dasgupta, M.; Hinde, D. J.; Simenel, C.; Simpson, E. C.; Williams, E.; Carter, I. P.; Cook, K. J.; Luong, D. H.; McNeil, S. D.; Ramachandran, K.; Vo-Phuoc, K.; Wakhle, A.

    2016-08-01

    Background: Nuclear reactions are complex, involving collisions between composite systems where many-body dynamics determines outcomes. Successful models have been developed to explain particular reaction outcomes in distinct energy and mass regimes, but a unifying picture remains elusive. The irreversible transfer of kinetic energy from the relative motion of the collision partners to their internal states, as is known to occur in deep inelastic collisions, has yet to be successfully incorporated explicitly into fully quantal reaction models. The influence of these processes on fusion is not yet quantitatively understood. Purpose: To investigate the population of high excitation energies in transfer reactions at sub-barrier energies, which are precursors to deep inelastic processes, and their dependence on the internuclear separation. Methods: Transfer probabilities and excitation energy spectra have been measured in collisions of O,1816,19F+208Pb , at various energies below and around the fusion barrier, by detecting the backscattered projectile-like fragments in a Δ E -E telescope. Results: The relative yields of different transfer outcomes are strongly driven by Q values, but change with the internuclear separation. In 16O+208Pb , single nucleon transfer dominates, with a strong contribution from -2 p transfer close to the Coulomb barrier, though this channel becomes less significant in relation to the -2 p 2 n transfer channel at larger separations. For 18O+208Pb , the -2 p 2 n channel is the dominant charge transfer mode at all separations. In the reactions with 19F,-3 p 2 n transfer is significant close to the barrier, but falls off rapidly with energy. Multinucleon transfer processes are shown to lead to high excitation energies (up to ˜15 MeV), which is distinct from single nucleon transfer modes which predominantly populate states at low excitation energy. Conclusions: Kinetic energy is transferred into internal excitations following transfer, with this

  13. Chronicling a century of lead pollution in Mexico: stable lead isotopic composition analyses of dated sediment cores.

    PubMed

    Soto-Jimenez, Martin F; Hibdon, Sharon A; Rankin, Charley W; Aggarawl, Jugdeep; Ruiz-Fernandez, A Carolina; Paez-Osuna, Federico; Flegal, A Russell

    2006-02-01

    Analyses of lead isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of dated sediment cores from two coastal estuaries and two inland lakes chronicle the predominance of industrial lead emissions in Mexico over the past century. These isotopic ratios exhibit a shift in composition from the turn of the previous century (1900) that corresponds with measurable increases (from 2- to 10-fold) in lead concentrations in the cores above their baseline values (3-22 microg/g)--both changes are consistent with the development of Mexican lead production for export and the manufacture of tetraethyl lead additives for Mexican gasolines. While subsequent changes in lead concentrations in the cores correspond with calculated emissions from the combustion of leaded gasoline in Mexico, isotopic compositions of the cores remain relatively constant throughout most of the 1900s (e.g., 206Pb/207Pb = 1.200 +/- 0.003; 208Pb/207Pb = 2.463 +/- 0.004). That isotopic constancy is attributed to the widespread pollution from lead production in Mexico and the dispersion of some of that lead used as an additive in Mexican gasolines.

  14. Comparison of the concentrations of metal elements and isotopes of lead found in rice and rice bran.

    PubMed

    Dai, Shouhui; Yang, Hui; Yang, Lan; Wang, Fuhua; Du, Ruiying; Wen, Dian

    2014-08-01

    Very few studies have investigated the difference in the distribution of metal elements between rice and rice bran samples. In this study, the concentrations of 27 metal elements (Li, Be, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, and U) in 56 polished rice and their corresponding bran samples were determined. A significant difference in concentrations of all elements except Ag and Cd was found between rice and bran (P < 0.05), with bran/rice ratios of 1.21 to 36.3. High concentrations of metal elements, especially that of the heavy metal Cr, in bran samples present a potential safety issue for bran products, such as food and feed containing bran. Pb isotope ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) ratios also were determined. The (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in bran were generally higher than those in rice (P < 0.0001), and rice and bran samples were distinctly different from each other, indicating that Pb isotope composition is an effective for discriminating between bran and rice samples.

  15. Field isotopic study of lead fate and compartmentalization in earthworm-soil-metal particle systems for highly polluted soil near Pb recycling factory.

    PubMed

    Goix, Sylvaine; Mombo, Stéphane; Schreck, Eva; Pierart, Antoine; Lévêque, Thibaut; Deola, Frédéric; Dumat, Camille

    2015-11-01

    Earthworms are important organisms in soil macrofauna and play a key role in soil functionality, and consequently in terrestrial ecotoxicological risk assessments. Because they are frequently observed in soils strongly polluted by metals, the influence of earthworm bioturbation on Pb fate could therefore be studied through the use of Pb isotopes. Total Pb concentrations and isotopic composition ((206)Pb, (207)Pb and (208)Pb) were then measured in earthworms, casts and bulk soils sampled at different distance from a lead recycling factory. Results showed decreasing Pb concentrations with the distance from the factory whatever the considered matrix (bulk soils, earthworm bodies or cast samples) with higher concentrations in bulk soils than in cast samples. The bivariate plot (208)Pb/(206)Pb ratios versus (206)Pb/(207)Pb ratios showed that all samples can be considered as a linear mixing between metallic process particulate matter (PM) and geochemical Pb background. Calculated anthropogenic fraction of Pb varied between approximately 84% and 100%. Based on Pb isotopic signatures, the comparison between casts, earthworms and bulk soils allowed to conclude that earthworms preferentially ingest the anthropogenic lead fraction associated with coarse soil organic matter. Actually, soil organic matter was better correlated with Pb isotopic ratios than with Pb content in soils. The proposed hypothesis is therefore a decrease of soil organic matter turnover due to Pb pollution with consequences on Pb distribution in soils and earthworm exposure. Finally, Pb isotopes analysis constitutes an efficient tool to study the influence of earthworm bioturbation on Pb cycle in polluted soils.

  16. One century sedimentary record of lead and zinc pollution in Yangzong Lake, a highland lake in southwestern China.

    PubMed

    Zhang, Enlou; Liu, Enfeng; Shen, Ji; Cao, Yanmin; Li, Yanling

    2012-01-01

    Reconstruction of trace metal pollution histories and sources may help us to regulate current pollutant discharge. This is especially important for the highland lakes in southwestern China, which are facing trace metals pollution. We present sedimentary records of 11 metals accumulated in Yangzong Lake since the 1870's, a highland lake in southwestern China. Pollution of lead and zinc (Pb and Zn) was differentiated based on principal component analysis, geochemical normalization, and lead isotope ratios. Nearly all the metals as well as grain size composition show generally constant values before the mid-1980's, denoting stable detrital input in the catchment. Fluctuations in the concentrations of the metals as well as grain size composition since the mid-1980's indicate an increase in soil erosion with strengthened human disturbance in the catchment. After geochemical normalization, Pb and Zn showed constant values before 1990 AD and then a gradual increase in parallel with the variations in 208Pb/206Pb and 207Pb/206Pb ratios, indicating that Pb and Zn pollution occurred. Combining the data of 208pb/206Pb and 207Pb/6Pb ratios in the sediments of Yangzong Lake, leaded gasoline, Pb-Zn ore and coal, and consumption or production historical trends, we deduced that the enhanced Pb and Zn pollution in Yangzong Lake is caused primarily by ore mining and refining.

  17. Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments

    NASA Astrophysics Data System (ADS)

    Ning-jing, Hu; Peng, Huang; Hui, Zhang; Ai-mei, Zhu; Ji-hua, Liu; Jun, Zhang; Lian-hua, He

    2015-10-01

    To investigate the source of Pb within Bohai Bay, Pb concentrations and Pb isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of surface sediments in this area were determined. The Pb concentration in this bay varied widely from 6.9 to 39.2 μg/g (average: 21.8±7.8 μg/g), and the Pb isotopic compositions ranged from 0.8338 to 0.8864 (average: 2.0997±0.0180) for 208Pb/206Pb and from 2.0797 to 2.1531 (average: 0.8477±0.0135) for 207Pb/206Pb, presenting in three distinct clusters. The Pb isotopic ratios of sediments from the northeastern (NE zone) and northwestern (NW zone) coastal areas were significantly influenced by anthropogenic sources such as coal combustion and automobile emission. In sediments from the central and southern Bohai Bay (C-S zone); however, Pb mainly originated from the Yellow River catchment, as a result of lithogenic sediment (from rock weathering) accumulation. The Pb isotopic ratios further indicate that, apart from riverine inputs, the neighboring large-scale ports and aerosols significantly contributed to the anthropogenic Pb contained in these sediments. Pb contamination in the Haihe and Luanhe river mouths as well as in the regions near ports is also suggested from anthropogenic enrichment factors. As cities and ports continue to develop around Bohai Bay, a long-term extensive sewage monitoring program is highly recommended.

  18. Historical record of metal accumulation and lead source in the southeastern coastal region of Korea.

    PubMed

    Lim, Dhong-il; Jung, Seung Woon; Choi, Man Sik; Kang, Sun Mee; Jung, Hoi Soo; Choi, Jin Yong

    2013-09-15

    Concentrations of heavy metals and Pb isotopes were measured in the 1-M HCl leaching fraction of core sediments spanning the last 400 years. This sedimentary record of pollution history in metal concentrations shows a good correlation with the increases in industrialization, urbanization, and energy consumption since 1901s. Notably, the Pb concentration and the (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios were constant before the 1910s (16.7 μg/g, 0.844, and 2.098, respectively), whereas they increased steadily up to 21.9 μg/g, 0.848, and 2.101 after the 1910s. The correlations between Pb isotope ratios ((206)Pb, (207)Pb, and (208)Pb) showed different linear regression trends for core sediments before and after the 1910s, indicating differences in Pb sources. Our interpretation suggests that the source of anthropogenic Pb in Korean coastal region and the Yellow Sea shelf was presumed to be Chinese coals or ores, which have also played a major role as sources of atmospheric particulate Pb.

  19. Study of multi-nucleon transfer reactions in 58, 64Ni + 207Pb collisions at the velocity filter SHIP

    NASA Astrophysics Data System (ADS)

    Comas, V. F.; Heinz, S.; Hofmann, S.; Ackermann, D.; Heredia, J. A.; Heßberger, F. P.; Khuyagbaatar, J.; Kindler, B.; Lommel, B.; Mann, R.

    2013-09-01

    We investigated multi-nucleon transfer reactions in collisions of 58Ni + 207Pb and 64Ni + 207Pb at Coulomb barrier energies. The new aspect is that we used a velocity filter (SHIP at GSI) for the separation of the heavy target-like transfer products from background events. The isotopic identification was performed via the decay properties of the reaction products. The goal of the experiment was to study the characteristics of multi-nucleon transfer reactions in the region of heavy nuclei and the applicability of existing separation and detection techniques, which are usually used for identification of heavy fusion-evaporation residues, to heavy transfer products. This was motivated by recent theoretical results from macroscopic-microscopic models which suggest deep inelastic transfer reactions in heavy systems as a means to produce new neutron-rich isotopes in the region of N = 126 and in the region of superheavy nuclei. In this paper we present the isotopic yields, the excitation functions and the excitation energies of the heavy transfer products with Z > 82 as well as the influence of shell effects on the reaction products. The influence of the different neutron numbers of the projectiles is also discussed.

  20. Optimization of an acidic digestion method for the determination of total Pb concentration and its isotope ratios in human blood using ICP-QMS.

    PubMed

    Pérez-Rodríguez, Rebeca Y; Castro-Larragoitia, Javier; Alfaro-De La Torre, María C; Díaz-Barriga, Fernando

    2017-03-21

    Adverse effects of lead (Pb) on human health are observed even at levels below 5 μg/dL, affecting principally the children population and suggesting that there is not a safe exposure level. The determination of Pb isotopic ratios (LIRs) in biological and environmental samples, is an appropriate tool to track and control the exposure sources, because LIRs constitutes the pollutant's isotopic signature and hence can be used to identify sources of Pb emission. This study proposes the optimization of a method in order to significantly reduce the biological samples' matrix interferences, and improves precision and accuracy in the measurements of LIRs. Four total blood digestion methods were evaluated and the results were subjected to statistical methods (ANOVA) determining the combination of HNO3:H2O2 (2:1 v v(-1))/g from a sample on a hot plate as the best of them. For the method's validation, detection and quantification limits, linearity range, intermediate precision and recovery were evaluated. The total Pb (PbT) and LIRs were performed by ICP-QMS, defining the optimal value of detector dead time (DT), and correcting mass bias and instrumental drift for this matrix. LIRs based on (206)Pb, (207)Pb and (208)Pb were determined at high precision (%RSD 0.03-0.49%), than those involving (204)Pb (%RSD > 0.8). The optimized methodology can be used to identify pollution sources in blood and environmental samples using LIRs ((206)Pb/(207)Pb, (207)Pb/(208)Pb, (208)Pb/(206)Pb, etc.) in a trustworthy and simple way, with accurate results.

  1. First observation of high-spin states in {sup 214}Po: Probing the valence space beyond {sup 208}Pb

    SciTech Connect

    Astier, Alain; Porquet, Marie-Genevieve

    2011-01-15

    Excited states in {sup 214}Po have been populated using the {sup 18}O + {sup 208}Pb reaction at 85-MeV beam energy and studied with the Euroball IV {gamma}-multidetector array. The level scheme has been built up to {approx}2.7-MeV excitation energy and spin I=12({h_bar}/2{pi}) from the triple-{gamma} coincidence data. Spin and parity values of most of the observed states have been assigned from the {gamma}-angular properties. The configurations of the yrast states are discussed using results of empirical shell-model calculations and by analogy with the neighboring nuclei. The {sup 214}Po level scheme established in this work constitutes an important step for the determination of the effective nucleon-nucleon interactions beyond N=126.

  2. Similarity of nuclear structure in the {sup 132}Sn and {sup 208}Pb regions: Proton-neutron multiplets

    SciTech Connect

    Coraggio, L.; Gargano, A.; Covello, A.; Itaco, N.

    2009-08-15

    Starting from the striking similarity of proton-neutron multiplets in {sup 134}Sb and {sup 210}Bi, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the V{sub low-k} approach. The calculated results for {sup 136}Sb, {sup 212}Bi, {sup 136}I, and {sup 212}At are in very good agreement with the available experimental data. The similarity between {sup 132}Sn and {sup 208}Pb regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.

  3. Volatilized lead from Apollo 12 and 14 soils.

    NASA Technical Reports Server (NTRS)

    Doe, B. R.; Tatsumoto, M.

    1972-01-01

    Lead in some Apollo-12 and -14 soils and breccias was volatilized under vacuum at temperature intervals of 0 to 600 C, 600 to 800 C, 800 to 1000 C, and 1000 to 1350 C. It is found that the Pb(206)/Pb(204) ratio increases and the Pb(207)/Pb(206) ratio decreases in the temperature range between 600 and 1000 C. The Pb(208)/Pb(206) ratios decrease from a value of 2 at 600 C to a value of 0.7 at 1350 C. These and other data suggest a secondary isochron age of about 4200 million years.

  4. Pb-207/Pb-206 ages of individual mineral phases in Luna 20 material by ion microprobe mass analysis.

    NASA Technical Reports Server (NTRS)

    Andersen, C. A.; Hinthorne, J. R.

    1973-01-01

    Ion microprobe analyses of returned lunar material have helped to demonstrate that U, Th, and radiogenic Pb are concentrated in small accessory mineral phases. It is possible to measure the isotopic composition of this Pb and obtain a radiometric Pb-207/Pb-206 age for the mineral. The ages so derived compare favorably with crystallization ages determined by conventional methods. A grain mount (22003,2/6) of Luna 20 material was searched for such accessory mineral phases, and two were found. One of these phases give an age of 4.12 plus or minus 0.04 b.y. and the other an age of 4.42 plus or minus 0.11 b.y. Ages of minerals dated by the ion probe in Apollo samples 14310 and 15555 are given for comparison. Data on the upper limit for Pb concentration in the outermost surface layers of free lunar soil particles are also given.

  5. Lead pollution in subtropical ecosystems on the SE Gulf of California Coast: a study of concentrations and isotopic composition.

    PubMed

    Soto-Jiménez, Martin F; Páez-Osuna, Federico; Scelfo, Genine; Hibdon, Sharon; Franks, Rob; Aggarawl, Jugdeep; Flegal, A Russell

    2008-10-01

    Lead pollution was investigated in environmental matrices and biological indicators collected from two typical subtropical coastal ecosystems in the southeast Gulf of California, Mexico. Lead concentrations and isotopic compositions ((206)Pb/(207)Pb and (208)Pb/(207)Pb) were measured using high resolution inductively-coupled plasma-mass spectrometry (HR-ICP-MS) and thermal ionization mass spectrometry (TIMS), respectively. Lead in surface estuary sediments (10.0-34.2microgg(-1)) and particulate Pb (25.0-128.7microgg(-1), >98% of total Pb) in the water column were significantly higher than levels in natural bedrock soils (15.1+/-8.3microgg(-1)) and river runoff (1.9+/-1.4microgg(-1)). Aquatic plants had Pb concentrations between 2.5 and 7.2microgg(-1), while those in macroalgae ranged from 3 to 5microgg(-1). The ranges of mean Pb concentrations in the aquatic animals studied (ranges in microgg(-1)) were as follows: zooplankton 32+/-3, mussels 2.3-3.9, oysters 1.9-7.9, snail 2.0-7.7, barnacles 0.1-18.5, fish 1.4-8.9, crab 6.3-40.2 and polychaetae 8.5-16.7. Pb values in 20-40% of oyster and fish samples and in all samples of crab exceeded acceptable levels for a food source for human consumption. Pb isotope ratios (206)Pb/(207)Pb, (208)Pb/(207)Pb in biota ranged from 1.188 to 1.206 and 2.448 to 2.470, respectively. A plot of (206)Pb/(207)Pb versus (208)Pb/(207)Pb for the environmental and biological samples collected from two study areas indicates that they contain lead from ores mined in Mexico and used in the past to produce leaded gasoline in use until 1997, natural Pb weathered from the Sierra Madre Occidental mother rock, and the later influence of inputs from a more radiogenic source related to industrial activity in the United States. Statistical software IsoSource results revealed that the Pb contained in environmental matrices and biomonitors is mostly derived from gasoline (20-90%) and US emissions (10-40%).

  6. Direct ion microprobe U-Pb dating of fossil tooth of a Permian shark

    NASA Astrophysics Data System (ADS)

    Sano, Yuji; Terada, Kentaro

    1999-12-01

    We report here direct ion microprobe dating of fossil tooth (dentine) of a Permian fresh-water shark, Orthacanthus senckenbergianus using the SHRIMP instrument recently installed at Hiroshima University. Fifteen spots on the small sample (approximately 2 mm×1 mm) indicate a 238U/ 206Pb isochron age of 266±18 Ma and a Tera-Wasserburg concordia intercept age of 266±24 Ma in a three-dimensional 238U/ 206Pb- 207Pb/ 206Pb- 204Pb/ 206Pb diagram. These Permian ages are consistent with a 235U/ 207Pb age of 453±170 Ma and a 232Th- 208Pb age of 235±310 Ma, suggesting indistinguishable depositional and early diagenetic ages of the fossil in its sedimentary sequences. The success of the method depends on the chemical fractionation of uranium from lead in a specimen a few hundred microns in size and the consequent variations in lead isotopic compositions due to radioactive decay.

  7. Double-magic nature of 132Sn and 208Pb through lifetime and cross-section measurements.

    PubMed

    Allmond, J M; Stuchbery, A E; Beene, J R; Galindo-Uribarri, A; Liang, J F; Padilla-Rodal, E; Radford, D C; Varner, R L; Ayres, A; Batchelder, J C; Bey, A; Bingham, C R; Howard, M E; Jones, K L; Manning, B; Mueller, P E; Nesaraja, C D; Pain, S D; Peters, W A; Ratkiewicz, A; Schmitt, K T; Shapira, D; Smith, M S; Stone, N J; Stracener, D W; Yu, C-H

    2014-05-02

    Single-neutron states in (133)Sn and (209)Pb, which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the ((9)Be, (8)Be) one-neutron transfer reaction in inverse kinematics using particle-γ coincidence spectroscopy. In addition, the s(1/2) single-neutron hole-state candidate in (131)Sn was populated by ((9)Be, (10)Be). Doubly closed-shell (132)Sn (radioactive) and (208)Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, γ-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared with shell-model expectations. The results include a new transition and precise level energy for the 3p(1/2) candidate in (133)Sn, new absolute cross sections for the 1h(9/2) candidate in (133)Sn and 3s(1/2) candidate in (131)Sn, and new lifetimes for excited states in (133)Sn and (209)Pb. This is the first report on excited-state lifetimes of (133)Sn, which allow for a unique test of the nuclear shell model and (132)Sn double-shell closure.

  8. Double-magic nature of 132Sn and 208Pb through lifetime and cross-section measurements

    SciTech Connect

    Allmond, James M; Stuchbery, Andrew E; Beene, James R; Galindo-Uribarri, Alfredo {nmn}; Liang, J Felix; Padilla-Rodal, Elizabeth; Radford, David C; Varner Jr, Robert L; Ayres, A.; Batchelder, J. C.; Bey, A.; Bingham, C. R.; Howard, Meredith E; Jones, K. L.; Manning, Brett M; Mueller, Paul Edward; Nesaraja, Caroline D; Pain, Steven D; Peters, William A; Ratkiewicz, Andrew J; Schmitt, Kyle; Shapira, Dan; Smith, Michael Scott; Stone, N. J.; Stracener, Daniel W; Yu, Chang-Hong

    2014-01-01

    Single-neutron states in 133Sn and 209Pb, which are analogous to single electrons outside of closed atomic shells in alkali metals, were populated by the (9Be,8Be) one-neutron transfer reaction in inverse kinematics using particle-gamma coincidence spectroscopy. In addition, the s1/2 single-neutron hole-state candidate in 131Sn was populated by (9Be,10Be). Doubly closed-shell 132Sn (radioactive) and 208Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, gamma-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared to shell-model expectations. The results include a new transition and precise level energy for the 3p1/2 candidate in 133Sn, new absolute cross sections for the 1h9/2 candidate in 133Sn and 3s1/2 candidate in 131Sn, and new lifetimes for excited states in 133Sn and 209Pb. This is the first report on excited-state lifetimes of 133Sn, which provide a unique signature of the single-neutron states and 132Sn double-shell closure.

  9. Structure of /sup 209/Bi deduced from the /sup 208/Pb(t,2n. gamma. ) reaction

    SciTech Connect

    Maier, K.H.; Nail, T.; Sheline, P.K.

    1983-04-01

    States in /sup 209/Bi were populated with the /sup 208/Pb(t,2n) reaction. Incident triton energies between 11 and 16 MeV were used. Gamma-ray excitation functions, angular distributions, and ..gamma..-..gamma..-time coincidence spectra were measured. Approximately 50 newly-observed ..gamma.. rays have been assigned to transitions in /sup 209/Bi. Previously-unresolved doublets at E/sub x/ = 2600, 3135, and 3154 keV have been identified. A new level at 3270 keV is reported, and the 3197-keV level is verified. /sup 209/Bi level energies are reported with an accuracy of 600 eV or less. A level scheme for E/sub x/<4.14 MeV is presented, including spin-parity assignments. A new M1 transition between the (5/2)/sup +/ and (3/2)/sup +/ members of the ..pi..h/sub 9/2/x3/sup -/ septuplet is reported. The 19 levels belonging to the ..nu..g/sub 9/2/p/sub 1/2/ /sup -1/, ..pi..h/sub 9/2/ are identified.

  10. Simultaneous analysis of the elastic scattering and breakup channel for the reaction 11Li+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Fernández-García, J. P.; Cubero, M.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Borge, M. J. G.; Buchmann, L.; Diget, C. A.; Falou, H. A.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gómez-Camacho, J.; Kanungo, R.; Lay, J. A.; Madurga, M.; Martel, I.; Moro, A. M.; Mukha, I.; Nilsson, T.; Rodríguez-Gallardo, M.; Sánchez-Benítez, A. M.; Shotter, A.; Tengblad, O.; Walden, P.

    2015-10-01

    We present a detailed analysis of the elastic scattering and breakup channel for the reaction of 11Li on 208Pb at incident laboratory energies of 24.3 and 29.8 MeV, measured at the radioactive ion beam facility of TRIUMF, in Vancouver, Canada. A large yield of 9Li fragments was detected by four charged particle telescopes in a wide angular range. The experimental angular and energy distributions of these 9Li fragments have been compared to coupled-reaction-channel and continuum-discretized coupled-channel calculations. The large production of 9Li fragments at small angles can be explained by considering a direct breakup mechanism, while at medium-large angles a competition between direct breakup and neutron transfer to the continuum of the 208Pb target was observed.

  11. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    SciTech Connect

    Pajtler, M. Varga; Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N.; Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J.; Gadea, A.; Haas, F.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F.; Märginean, N.; Pollarolo, G.; and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  12. 207Pb NMR in minium, Pb3O4: Evidence for the [Pb2]4+ ion andpossible relativistic effects in the Pb-Pb bond

    SciTech Connect

    Gabuda, S.P.; Kozlova, S.G.; Terskikh, V.V.; Dybowski, C.; Neue,G.; Perry, D.L.

    1999-07-18

    Solid Pb3O4 has been studied with 207Pb nuclear magnetic resonance (NMR) spectroscopy. The 207Pb NMR chemical-shift tensor of the Pb2+ site has principal values of delta 11=1980+-5 ppm, delta 22=1540+-5ppm, and delta 33=-1108+-10 ppm; delta iso=804+-10 ppm. The chemical-shift tensor of the Pb4+ site is axial, with principal values delta bar bar=-1009+-3 ppm and delta perpendicular=1132+-3 ppm; delta iso=-1091+-3ppm. The Pb4+ Pb2+ scalar coupling constant JPb Pb=2.3+-0.1 kHz. The main contribution to the Pb2+ chemical-shift anisotropy is proposed to arise from an exchange interaction in the Pb2+ Pb2+ pairs, conventionally regarded as molecular [Pb2]4+ ions.

  13. Metallic elements and isotope of Pb in wet precipitation in urban area, South America

    NASA Astrophysics Data System (ADS)

    Migliavacca, Daniela Montanari; Teixeira, Elba Calesso; Gervasoni, Fernanda; Conceição, Rommulo Vieira; Raya Rodriguez, Maria Teresa

    2012-04-01

    The atmosphere of urban areas has been the subject of many studies to show the atmospheric pollution in large urban centers. By quantifying wet precipitation through the analysis of metallic elements (ICP/AES) and Pb isotopes, the wet precipitation of the Metropolitan Area of the Porto Alegre (MAPA), Brazil, was characterized. The samples were collected between July 2005 and December 2007. Zn, Fe and Mn showed the highest concentration in studied sites. Sapucaia do Sul showed the highest average for Zn, due to influence by the steel plant located near the sampling site. The contribution of anthropogenic emissions from vehicular activity and steel plants in wet precipitation and suspended particulate matter in the MAPA was identified by the isotopic signatures of 208Pb/207Pb and 206Pb/207Pb. Moreover the analyses of the metallic elements allowed also to identify the contribution of other anthropic sources, such as steel plants and oil refinery.

  14. Impact of submersible pumps on Pb constituents in residential wells.

    PubMed

    Sidle, W C; Li, P

    2008-02-01

    Dissolved Pb in 51 domestic wells screened from 18 to 48 m in glacial tills and outwash deposits were examined in conjunction with the characteristics of their corresponding submersible pump. Pb concentrations, ranging from 0.8 to 24.9 microg l(-1), entering residential water supplies were measured during 2001-2004 in the Royal watershed, Maine. Principal component analyses assisted the weighting of pump age, well screen depth, and draw time variables. Preliminary Pb sequestration significance in the boreholes was predicted from geochemical speciation and synchrotron XAS analyses. Nascent 207Pb/206Pb and 208Pb/206Pb isotope analyses assisted the discrimination of possibly leached Pb from submersible pump materials among geogenic sources.

  15. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

    NASA Technical Reports Server (NTRS)

    Hegner, E.; Tatsumoto, M.

    1987-01-01

    Isotopic Pb, Sr, and Nd data were collected by the Alvin submersible from seven basalt glasses in the southern Juan de Fuca Ridge (JFR), giving similar ratios for Pb-206/Pb-204 of about 18.45, for Pb-207/Pb-204 of about 15.47, for Pb-208/Pb-204 of about 37.81, for Sr-87/Sr-86 of about 0.70249, and for Nd-143/Nd-144 of about 0.51315. Data suggest that the basalts are all cogenetic, and that four of the samples are also comagmatic. It is concluded that isotopic data for the JFR and seamount basalts provide additional support for the mantle blob cluster model (Allegre et al., 1984), suggesting the involvement of multiple components in the genesis of ridge basalts, and including an unusual end-member that has nonradiogenic Sr and variable Pb-206/Pb-204 isotopic compositions.

  16. Tracing fetal and childhood exposure to lead using isotope analysis of deciduous teeth.

    PubMed

    Shepherd, Thomas J; Dirks, Wendy; Roberts, Nick M W; Patel, Jaiminkumar G; Hodgson, Susan; Pless-Mulloli, Tanja; Walton, Pamela; Parrish, Randall R

    2016-04-01

    We report progress in using the isotopic composition and concentration of Pb in the dentine and enamel of deciduous teeth to provide a high resolution time frame of exposure to Pb during fetal development and early childhood. Isotope measurements (total Pb and (208)Pb/(206)Pb, (207)Pb/(206)Pb ratios) were acquired by laser ablation inductively coupled mass spectrometry at contiguous 100 micron intervals across thin sections of the teeth; from the outer enamel surface to the pulp cavity. Teeth samples (n=10) were selected from two cohorts of children, aged 5-8 years, living in NE England. By integrating the isotope data with histological analysis of the teeth, using the daily incremental lines in dentine, we were able to assign true estimated ages to each ablation point (first 2-3 years for molars, first 1-2 years for incisors+pre-natal growth). Significant differences were observed in the isotope composition and concentration of Pb between children, reflecting differences in the timing and sources of exposure during early childhood. Those born in 2000, after the withdrawal of leaded petrol in 1999, have the lowest dentine Pb levels (<0.2µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.126-2.079) (208)Pb/(206)Pb (mean ±2σ: 0.879-0.856) ratios that correlate very closely with modern day Western European industrial aerosols (PM10, PM2.5) suggesting that diffuse airborne pollution was probably the primary source and exposure pathway. Legacy lead, if present, is insignificant. For those born in 1997, dentine lead levels are typically higher (>0.4µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.145-2.117) (208)Pb/(206)Pb (mean ±2σ: 0.898-0.882) ratios that can be modelled as a binary mix between industrial aerosols and leaded petrol emissions. Short duration, high intensity exposure events (1-2 months) were readily identified, together with evidence that dentine provides a good proxy for childhood changes in the isotope composition of blood Pb. Our pilot study confirms that

  17. Lead and strontium isotopic evidence for crustal interaction and compositional zonation in the source regions of Pleistocene basaltic and rhyolitic magmas of the Coso volcanic field, California

    USGS Publications Warehouse

    Bacon, C.R.; Kurasawa, H.; Delevaux, M.H.; Kistler, R.W.; Doe, B.R.

    1984-01-01

    The isotopic compositions of Pb and Sr in Pleistocene basalt, high-silica rhyolite, and andesitic inclusions in rhyolite of the Coso volcanic field indicate that these rocks were derived from different levels of compositionally zoned magmatic systems. The 2 earliest rhyolites probably were tapped from short-lived silicic reservoirs, in contrast to the other 36 rhyolite domes and lava flows which the isotopic data suggest may have been leaked from the top of a single, long-lived magmatic system. Most Coso basalts show isotopic, geochemical, and mineralogic evidence of interaction with crustal rocks, but one analyzed flow has isotopic ratios that may represent mantle values (87Sr/86Sr=0.7036,206Pb/204Pb=19.05,207Pb/204Pb=15.62,208Pb/204Pb= 38.63). The (initial) isotopic composition of typical rhyolite (87Sr/86Sr=0.7053,206Pb/204Pb=19.29,207Pb/204Pb= 15.68,208Pb/204Pb=39.00) is representative of the middle or upper crust. Andesitic inclusions in the rhyolites are evidently samples of hybrid magmas from the silicic/mafic interface in vertically zoned magma reservoirs. Silicic end-member compositions inferred for these mixed magmas, however, are not those of erupted rhyolite but reflect the zonation within the silicic part of the magma reservoir. The compositional contrast at the interface between mafic and silicic parts of these systems apparently was greater for the earlier, smaller reservoirs. ?? 1984 Springer-Verlag.

  18. Lead Isotope Characterization of Petroleum Fuels in Taipei, Taiwan

    PubMed Central

    Yao, Pei-Hsuan; Shyu, Guey-Shin; Chang, Ying-Fang; Chou, Yu-Chen; Shen, Chuan-Chou; Chou, Chi-Su; Chang, Tsun-Kuo

    2015-01-01

    Leaded gasoline in Taiwan was gradually phased out from 1983 to 2000. However, it is unclear whether unleaded gasoline still contributes to atmospheric lead (Pb) exposure in urban areas. In this study, Pb isotopic compositions of unleaded gasolines, with octane numbers of 92, 95, 98, and diesel from two local suppliers in Taipei were determined by multi-collector inductively coupled plasma mass spectrometry with a two-sigma uncertainty of ± 0.02 %. Lead isotopic ratios of vehicle exhaust (208Pb/207Pb: 2.427, 206Pb/207Pb: 1.148, as estimated from petroleum fuels) overlap with the reported aerosol data. This agreement indicates that local unleaded petroleum fuels, containing 10–45 ng·Pb·g−1, are merely one contributor among various sources to urban aerosol Pb. Additionally, the distinction between the products of the two companies is statistically significant in their individual 208Pb/206Pb ratios (p-value < 0.001, t test). Lead isotopic characterization appears to be applicable as a “fingerprinting” tool for tracing the sources of Pb pollution. PMID:25918913

  19. High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry.

    PubMed

    Paul, Maxence; Bridgestock, Luke; Rehkämper, Mark; van DeFlierdt, Tina; Weiss, Dominik

    2015-03-10

    A new method for the determination of seawater Pb isotope compositions and concentrations was developed, which combines and optimizes previously published protocols for the separation and isotopic analysis of this element. For isotopic analysis, the procedure involves initial separation of Pb from 1 to 2L of seawater by co-precipitation with Mg hydroxide and further purification by a two stage anion exchange procedure. The Pb isotope measurements are subsequently carried out by thermal ionization mass spectrometry using a (207)Pb-(204)Pb double spike for correction of instrumental mass fractionation. These methods are associated with a total procedural Pb blank of 28±21 pg (1sd) and typical Pb recoveries of 40-60%. The Pb concentrations are determined by isotope dilution (ID) on 50 mL of seawater, using a simplified version of above methods. Analyses of multiple aliquots of six seawater samples yield a reproducibility of about ±1 to ±10% (1sd) for Pb concentrations of between 7 and 50 pmol/kg, where precision was primarily limited by the uncertainty of the blank correction (12±4 pg; 1sd). For the Pb isotope analyses, typical reproducibilities (±2sd) of 700-1500 ppm and 1000-2000 ppm were achieved for (207)Pb/(206)Pb, (208)Pb/(206)Pb and (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb, respectively. These results are superior to literature data that were obtained using plasma source mass spectrometry and they are at least a factor of five more precise for ratios involving the minor (204)Pb isotope. Both Pb concentration and isotope data, furthermore, show good agreement with published results for two seawater intercomparison samples of the GEOTRACES program. Finally, the new methods were applied to a seawater depth profile from the eastern South Atlantic. Both Pb contents and isotope compositions display a smooth evolution with depth, and no obvious outliers. Compared to previous Pb isotope data for seawater, the (206)Pb/(204)Pb ratios are well correlated

  20. Lead contamination in cocoa and cocoa products: isotopic evidence of global contamination.

    PubMed

    Rankin, Charley W; Nriagu, Jerome O; Aggarwal, Jugdeep K; Arowolo, Toyin A; Adebayo, Kola; Flegal, A Russell

    2005-10-01

    In this article we present lead concentrations and isotopic compositions from analyses of cocoa beans, their shells, and soils from six Nigerian cocoa farms, and analyses of manufactured cocoa and chocolate products. The average lead concentration of cocoa beans was 206Pb/207Pb = 1.1548-1.1581; 208Pb/207Pb = 2.4344-2.4394) with those of finished cocoa products (206Pb/207Pb = 1.1475-1.1977; 208Pb/207Pb = 2.4234-2.4673). However, the much higher lead concentrations and larger variability in lead isotopic composition of finished cocoa products, which falls within the global range of industrial lead aerosols, indicate that most contamination occurs during shipping and/or processing of the cocoa beans and the manufacture of cocoa and chocolate products.

  1. Regional lead isotope study of a polluted river catchment: River Wear, Northern England, UK.

    PubMed

    Shepherd, Thomas J; Chenery, Simon R N; Pashley, Vanessa; Lord, Richard A; Ander, Louise E; Breward, Neil; Hobbs, Susan F; Horstwood, Matthew; Klinck, Benjamin A; Worrall, Fred

    2009-08-15

    High precision, lead isotope analyses of archived stream sediments from the River Wear catchment, northeast England (1986-88), provide evidence for three main sources of anthropogenic lead pollution; lead mining, industrial lead emissions and leaded petrol. In the upper catchment, pollution is totally controlled and dominated by large lead discharges from historic mining centres in the North Pennine Orefield ((208)Pb/(206)Pb, (207)Pb/(206)Pb ratios range from 2.0744-2.0954 and 0.8413-0.8554 respectively). In the lower catchment, co-extensive with the Durham Coalfield and areas of high population density, pollution levels are lower and regionally more uniform. Isotope ratios are systematically higher than in the upper catchment ((208)Pb/(206)Pb, (207)Pb/(206)Pb ratios range from 2.0856-2.1397 and 0.8554-0.8896 respectively) and far exceed values determined for the geogenic regional background. Here, the pollution is characterised by the atmospheric deposition of industrial lead and petrol lead. Lead derived from the combustion of coal, although present, is masked by the other two sources. Recent sediments from the main channel of the River Wear are isotopically indistinguishable from older, low order stream sediments of the North Pennine Orefield, indicating that contamination of the river by lead mining waste (up to several 1000 mg/kg Pb at some locations) continues to pose an environmental problem; a pattern that can be traced all the way to the tidal reach. Using within-catchment isotope variation and sediment lead concentrations, estimates can be made of the discharges from discrete mines or groups of mines to the overall level of lead pollution in the River Wear. As well as providing information pertinent to source apportionment and on-going catchment remediation measures, the database is a valuable resource for epidemiologists concerned with the health risks posed by environmental lead.

  2. Historical reconstruction of atmospheric lead pollution in central Yunnan province, southwest China: an analysis based on lacustrine sedimentary records.

    PubMed

    Liu, Enfeng; Zhang, Enlou; Li, Kai; Nath, Bibhash; Li, Yanling; Shen, Ji

    2013-12-01

    Atmospheric lead (Pb) pollution during the last century in central Yunnan province, one of the largest non-ferrous metal production centers in China, was reconstructed using sediment cores collected from Fuxian and Qingshui Lakes. Lead concentrations and isotopic ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) were measured in sediment cores from both lakes. The operationally defined chemical fractions of Pb in sediment core from Fuxian Lake were determined by the optimized BCR procedure. The chronology of the cores was reconstructed using (210)Pb and (137)Cs dating methods. Similar three-phase variations in isotopic ratios and enrichment factors of Pb were observed in the sediment cores from both lakes. Before the 1950s, the sediment data showed low (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios and enrichment factors (EFs=~1), indicating that the sedimentary Pb was predominantly of lithogenic origin. However, these indices were increased gradually between the 1950s and the mid-1980s, implying an atmospheric Pb deposition. The EFs and isotopic ratios of Pb reached their peak during recent years, indicating aggravating atmospheric Pb pollution. The average anthropogenic Pb fluxes since the mid-1980s were estimated to be 0.032 and 0.053 g m(-2) year(-1) recorded in Fuxian and Qingshui cores, respectively. The anthropogenic Pb was primarily concentrated in the reducible fraction. Combining the results of Pb isotopic compositions and chemical speciations in the sediment cores and in potential sources, we deduced that recent aggravating atmospheric Pb pollution in central Yunnan province should primarily be attributed to regional emissions from non-ferrous metal production industries.

  3. In situ U-Pb rutile dating by LA-ICP-MS: 208Pb correction and prospects for geological applications

    NASA Astrophysics Data System (ADS)

    Zack, Thomas; Stockli, Daniel F.; Luvizotto, George L.; Barth, Matthias G.; Belousova, Elena; Wolfe, Melissa R.; Hinton, Richard W.

    2011-09-01

    Rutile is a common accessory mineral that occurs in a wide spectrum of metamorphic rocks, such as in blueschists, eclogites, and granulites and as one of the most stable detrital heavy minerals in sedimentary rocks. The advent of rutile trace element thermometry has generated increased interest in a better understanding of rutile formation. This study documents important analytical advances in in situ LA-ICP-MS U/Pb geochronology of rutile: (1) Matrix matching, necessary for robust in situ dating is fulfilled by calibrating and testing several rutile standards (R10, R19, WH-1), including the presentation of new TIMS ages for the rutile standard R19 (489.5 ± 0.9 Ma; errors always stated as 2 s). (2) Initial common lead correction is routinely applied via 208Pb, which is possible due to extremely low Th/U ratios (usually <0.003) in most rutiles. Employing a 213 nm Nd:YAG laser coupled to a quadrupole ICP-MS and using R10 as a primary standard, rutile U/Pb concordia ages for the two other rutile standards (493 ± 10 Ma for R19; 2640 ± 50 Ma for WH-1) and four rutile-bearing metamorphic rocks (181 ± 4 Ma for Ivrea metapelitic granulite; 339 ± 7 Ma for Saidenbach coesite eclogite; 386 ± 8 Ma for Fjortoft UHP metapelite; 606 ± 12 Ma for Andrelandia metepelitic granulite) always agree within 2% with the reported TIMS ages and other dating studies from the same localities. The power of in situ U/Pb rutile dating is illustrated by comparing ages of detrital rutile and zircon from a recent sediment from the Christie Domain of the Gawler Craton, Australia. While the U/Pb age spectrum from zircons show several pronounced peaks that are correlated with magmatic episodes, rutile U/Pb ages are marked by only one pronounced peak (at ca 1,675 Ma) interpreted to represent cooling ages of this part of the craton. Rutile thermometry of the same detrital grains indicates former granulite-facies conditions. The methods outlined in this paper should find wide application in studies

  4. Investigation of constraints on few-neutron forces in neutron matter by empirical information on the neutron skin of 48Ca and 208Pb

    NASA Astrophysics Data System (ADS)

    Sammarruca, Francesca

    2016-11-01

    The neutron matter equation of state is calculated from two-neutron forces up to fifth order of the chiral expansion, and the order-by-order convergence of the predictions is investigated. Based on these equations of state, the binding energies and the neutron and proton density distributions in 208Pb and 48Ca are derived, with particular attention paid to the neutron skins, the focal point of this paper. Anticipating future experiments which will provide reliable information on the weak charge density in nuclei, the theoretical uncertainties and the possibility of constraining the size of few-neutron forces in neutron matter are discussed.

  5. Nuclear potentials for sub-barrier fusion and cluster decay in {sup 14}C, {sup 18}O+{sup 208}Pb systems

    SciTech Connect

    Sagaidak, R. N.; Tretyakova, S. P.; Khlebnikov, S. V.; Ogloblin, A. A.; Rowley, N.; Trzaska, W. H.

    2007-09-15

    Near-barrier fusion excitation functions for the {sup 14}C and {sup 18}O+{sup 208}Pb reactions have been analyzed in the framework of the barrier-passing model using different forms of the nuclear potential and the phenomenology of a fluctuating barrier. The best-fit fusion potentials were used to estimate cluster decay probabilities from the corresponding ground states of Ra and Th (i.e., for the inverse decay process). The analysis supports the ''{alpha}-decay-like'' scenario for carbon and oxygen emission from these nuclei.

  6. Stable lead isotope ratios in Alaskan arctic aerosols

    NASA Astrophysics Data System (ADS)

    Sturges, W. T.; Hopper, J. F.; Barrie, L. A.; Schnell, R. C.

    Aerosol samples collected at Barrow, Alaska, during February and March 1990 were found to have uniform stable lead isotope compositions. The mean 208Pb/ 207Pb ratio was 2.423±0.009 and the mean 206Pb/ 207Pb ratio was 1.161±0.014. The latter ratio is essentially the same as that obtained from an earlier study of aerosols at two Canadian stations in the High Arctic and is typical of, but not unique to, Eurasian sources of atmospheric lead. Further discriminating power was available in this study through the inclusion of 208Pb/ 207Pb ratios, which provided additional evidence that the former Soviet Union and eastern Europe are major contributors to atmospheric particulate lead in the Alaskan Arctic, accounting for around two-thirds of the particulate lead measured at Barrow. The remaining third of the lead is attributed to west European sources. There was no evidence for a substantial North American component, other than local contamination.

  7. Lead contamination and transfer in urban environmental compartments analyzed by lead levels and isotopic compositions.

    PubMed

    Hu, Xin; Sun, Yuanyuan; Ding, Zhuhong; Zhang, Yun; Wu, Jichun; Lian, Hongzhen; Wang, Tijian

    2014-04-01

    Lead levels and isotopic compositions in atmospheric particles (TSP and PM2.5), street dust and surface soil collected from Nanjing, a mega city in China, were analyzed to investigate the contamination and the transfer of lead in urban environmental compartments. The lead contents in TSP and PM2.5 are significantly higher than them in the surface soil and street dust (p < 0.05). The enrichment factor using the mass ratio of lead to the major crustal elements (Al, Sr, Ti and Fe) indicates significant lead enrichment in atmospheric particles. The plots of (206)Pb/(207)Pb vs.(208)Pb/(206)Pb and (206)Pb/(207)Pb vs. 1/Pb imply that the street dust and atmospheric particles (TSP and PM2.5) have very similar lead sources. Coal emissions and smelting activities may be the important lead sources for street dust and atmospheric particles (TSP and PM2.5), while the deposition of airborne lead is an important lead source for urban surface soil.

  8. ICP-MS measurements of lead isotopic ratios in soils heavily contaminated by lead smelting: tracing the sources of pollution.

    PubMed

    Ettler, Vojtech; Mihaljevic, Martin; Komárek, Michael

    2004-01-01

    The Pb isotopic composition (206Pb/207Pb and 208Pb/206Pb) in smelter-impacted soils was measured using a quadrupole-based ICP-MS. Four forest/tilled soil profiles were sampled according to the distance from the lead smelter in Príbram (Czech Republic), prevailing wind direction, geological background and soil type. The results were compared with the Pb isotopic composition of bedrocks and waste materials from Pb metallurgy (smelting slags, air-pollution-control residues). The isotopic composition of soils confirms the predominant role of metallurgy on the general pollution in the area. The highly contaminated soils from the vicinity of the smelter contain up to 35,300 mg Pb kg(-1) and exhibit an isotopic composition close to that of car battery processing (206Pb/207Pb up to 1.177). A coupled concentration/isotopic study of soil profiles showed that the smelter-induced pollution had penetrated even to the mineral soil horizons, indicating an important vertical mobility of Pb contaminant within the soil profile. The calculated downward penetration rate of Pb in soils ranges from 0.3 to 0.36 cm year(-1).

  9. Temporal evolution of lead isotope ratios in sediments of the Central Portuguese Margin: a fingerprint of human activities.

    PubMed

    Mil-Homens, Mário; Caetano, Miguel; Costa, Ana M; Lebreiro, Susana; Richter, Thomas; de Stigter, Henko; Trancoso, Maria A; Brito, Pedro

    2013-09-15

    Stable Pb isotope ratios ((206)Pb/(207)Pb, (208)Pb/(206)Pb), (210)Pb, Pb, Al, Ca, Fe, Mn and Si concentrations were measured in 7 sediment cores from the west coast of the Iberian Peninsula to assess the Pb contamination throughout the last 200 years. Independently of their locations, all cores are characterized by increasing Pb/Al rends not related to grain-size changes. Conversely, decreasing trends of (206)Pb/(207)Pb were found towards the present. This tendency suggest a change in Pb sources reflecting an increased proportion derived from anthropogenic activities. The highest anthropogenic Pb inventories for sediments younger than 1950s were found in the two shallowest cores of Cascais and Lisboa submarine canyons, reflecting the proximity of the Tagus estuary. Lead isotope signatures also help demonstrate that sediments contaminated with Pb are not constrained to estuarine-coastal areas and upper parts of submarine canyons, but are also to transferred to a lesser extent to deeper parts of the Portuguese Margin.

  10. The Solar System primordial lead

    NASA Astrophysics Data System (ADS)

    Blichert-Toft, Janne; Zanda, Brigitte; Ebel, Denton S.; Albarède, Francis

    2010-11-01

    Knowledge of the primordial isotope composition of Pb in the Solar System is critical to the understanding of the early evolution of Earth and other planetary bodies. Here we present new Pb isotopic data on troilite (FeS) nodules from a number of different iron meteorites: Canyon Diablo, Mundrabilla, Nantan, Seeläsgen, Toluca (IAB-IIICD), Cape York (IIIA), Mt Edith (IIIB), and Seymchan (pallasite). Lead abundances and isotopic compositions typically vary from one troilite inclusion to another, even within the same meteorite. The most primitive Pb was found in three leach fractions of two exceptionally Pb-rich Nantan troilite nodules. Its 204Pb/ 206Pb is identical to that of Canyon Diablo troilite as measured by Tatsumoto et al. [M. Tatsumoto, R.J. Knight, C.J. Allègre, Time differences in the formation of meteorites as determined from the ratio of lead-207 to lead-206, Science 180(1973) 1279-1283]. However, our measurements of 207Pb/ 206Pb and 208Pb/ 206Pb are significantly higher than theirs, as well as other older literature data obtained by TIMS, while consistent with the recent data of Connelly et al. [J.N. Connelly, M. Bizzarro, K. Thrane, J.A. Baker, The Pb-Pb age of Angrite SAH99555 revisited, Geochim. Cosmochim. Acta 72(2008) 4813-4824], a result we ascribe to instrumental mass fractionation having biased the older data. Our current best estimate of the Solar System primordial Pb is that of Nantan troilite, which has the following isotopic composition: 204Pb/ 206Pb = 0.107459(16), 207Pb/ 206Pb = 1.10759(10), and 208Pb/ 206Pb = 3.17347(28). This is slightly less radiogenic than the intercept of the bundle of isotopic arrays formed in 207Pb/ 206Pb- 204Pb/ 206Pb space by our measurements of Canyon Diablo, Nantan, Seeläsgen, Cape York, and Mundrabilla, as well as literature data, which, in spite of rather large uncertainties, suggests a common primordial Pb component for all of these meteorites. The radiogenic Pb present in most of these irons is dominantly

  11. Novel Manifestation of {alpha}-Clustering Structures: New '{alpha}+{sup 208}Pb' States in {sup 212}Po Revealed by Their Enhanced E1 Decays

    SciTech Connect

    Astier, A.; Porquet, M.-G.; Petkov, P.; Delion, D. S.; Schuck, P.

    2010-01-29

    Excited states in {sup 212}Po were populated by {alpha} transfer using the {sup 208}Pb({sup 18}O,{sup 14}C) reaction, and their deexcitation {gamma} rays were studied with the Euroball array. Several levels were found to decay by a unique E1 transition (E{sub {gamma}}<1 MeV) populating the yrast state with the same spin value. Their lifetimes were measured by the Doppler-shift attenuation method. The values, found in the range 0.1-1.4 ps, lead to very enhanced transitions, B(E1)=2x10{sup -2}-1x10{sup -3} W.u. These results are discussed in terms of an {alpha}-cluster structure which gives rise to states with non-natural-parity values, provided that the composite system cannot rotate collectively, as expected in the '{alpha}+{sup 208}Pb' case. Such states due to the oscillatory motion of the {alpha}-core distance are observed for the first time.

  12. Containing arsenic-enriched groundwater tracing lead isotopic compositions of common arsenical pesticides in a coastal Maine watershed

    USGS Publications Warehouse

    Ayuso, Robert A.; Foley, Nora K.; Robinson, Glipin R.; Colvin, A.S.; Lipfert, G.; Reeve, A.S.

    2006-01-01

    Arsenical pesticides and herbicides were extensively used on apple, blueberry, and potato crops in New England during the first half of the twentieth century. Lead arsenate was the most heavily used arsenical pesticide until it was officially banned. Lead arsenate, calcium arsenate, and sodium arsenate have similar Pb isotope compositions: 208Pb207Pb = 2.3839-2.4722, and 206Pb207Pb = 1.1035-1.2010. Other arsenical pesticides such as copper acetoarsenite (Paris green), methyl arsonic acid and methane arsonic acid, as well as arsanilic acid are widely variable in isotope composition. Although a complete understanding of the effects of historical use of arsenical pesticides is not available, initial studies indicate that arsenic and lead concentrations in stream sediments in New England are higher in agricultural areas that intensely used arsenical pesticides than in other areas. The Pb isotope compositions of pesticides partially overlap values of stream sediments from areas with the most extensive agricultural use. The lingering effects of arsenical pesticide use were tested in a detailed geochemical and isotopic study of soil profiles from a watershed containing arsenic-enriched ground water in coastal Maine. Acid-leach compositions of the soils represent lead adsorbed to mineral surfaces or held in soluble minerals (Fe- and Mn-hydroxides, carbonate, and some micaceous minerals), whereas residue compositions likely reflect bedrock compositions. The soil profiles contain labile Pb (acid-leach) showing a moderate range in 206Pb 207Pb (1.1870-1.2069), and 208Pb207Pb (2.4519-2.4876). Isotope values vary as a function of depth: the lowest Pb isotope ratios (e.g.,208Pb206Pb) representing labile lead are in the uppermost soil horizons. Lead contents decrease with depth in the soil profiles. Arsenic contents show no clear trend with depth. A multi-component mixing scheme that included lead from the local parent rock (Penobscot Formation), lead derived from combustion of

  13. The identification of lead ammunition as a source of lead exposure in First Nations: the use of lead isotope ratios.

    PubMed

    Tsuji, Leonard J S; Wainman, Bruce C; Martin, Ian D; Sutherland, Celine; Weber, Jean-Philippe; Dumas, Pierre; Nieboer, Evert

    2008-04-15

    The use of lead shotshell to hunt water birds has been associated with lead-contamination in game meat. However, evidence illustrating that lead shotshell is a source of lead exposure in subsistence hunting groups cannot be deemed definitive. This study seeks to determine whether lead shotshell constitutes a source of lead exposure using lead isotope ratios. We examined stable lead isotope ratios for lichens, lead shotshell and bullets, and blood from residents of Fort Albany and Kashechewan First Nations, and the City of Hamilton, Ontario, Canada. Data were analyzed using ANOVA and regression analyses. ANOVA of isotope ratios for blood revealed significant differences with respect to location, but not sex. Hamilton differed from both Kashechewan and Fort Albany; however, the First Nations did not differ from each other. ANOVA of the isotope ratios for lead ammunition and lichens revealed no significant differences between lichen groups (north and south) and for the lead ammunition sources (pellets and bullets). A plot of (206)Pb/(204)Pb and (206)Pb/(207)Pb values illustrated that lichens and lead ammunition were distinct groupings and only the 95% confidence ellipse of the First Nations group overlapped that of lead ammunition. In addition, partial correlations between blood-lead levels (adjusted for age) and isotope ratios revealed significant (p<0.05) positive correlations for (206)Pb/(204)Pb and (206)Pb/(207)Pb, and a significant negative correlation for (208)Pb/(206)Pb, as predicted if leaded ammunition were the source of lead exposure. In conclusion, lead ammunition was identified as a source of lead exposure for First Nations people; however, the isotope ratios for lead shotshell pellets and bullets were indistinguishable. Thus, lead-contaminated meat from game harvested with lead bullets may also be contributing to the lead body burden.

  14. U, Th, Pb and REE abundances and Pb 207/Pb 206 ages of individual minerals in returned lunar material by ion microprobe mass analysis.

    NASA Technical Reports Server (NTRS)

    Andersen, C. A.; Hinthorne, J. R.

    1972-01-01

    Results of ion microprobe analyses of Apollo 11, 12 and 14 material, showing that U, Th, Pb and REE are concentrated in accessory minerals such as apatite, whitlockite, zircon, baddeleyite, zirkelite, and tranquillityite. Th/U ratios are found to vary by over a factor of 40 in these minerals. K, Ba, Rb and Sr have been localized in a K rich, U and Th poor glass phase that is commonly associated with the U and Th bearing accessory minerals. Li is observed to be fairly evenly distributed between the various accessory phases. The phosphates have been found to have REE abundance patterns (normalized to the chondrite abundances) that are fairly flat, while the Zr bearing minerals have patterns that rise steeply, by factors of ten or more, from La to Gd. All the accessory minerals have large negative Eu anomalies. Radiometric age dates (Pb 207/Pb 206) of the individual U and Th bearing minerals compare favorably with the Pb 207/Pb 206 age of the bulk rocks.

  15. Anthropogenic and natural lead isotopes in Fe-hydroxides and Fe-sulphates in a watershed associated with arsenic-enriched groundwater, Maine, USA

    USGS Publications Warehouse

    Ayuso, Robert A.; Foley, Nora K.

    2008-01-01

    A survey of the natural and anthropogenic sources of lead contributing to secondary minerals in sulphidic schists associated with arsenic-enriched groundwater in Coastal Maine shows that the most likely source is natural Pb, particularly from coexisting sulphide minerals. The secondary minerals also reflect notable contributions from anthropogenic Pb. The Pb isotopes establish pathways by which Pb, and by inference As, could have been transported from As-bearing minerals (arsenian pyrite, arsenopyrite, lollingite, orpiment, arsenic oxide and others), via sulphide oxidation or carbonation reactions into multiple generations of secondary minerals (goethite, hematite, jarosite, natrojarosite and others). Lead isotopic compositions of the sulphides and secondary minerals determined by thermal ionization mass spectrometry (n=53) range widely. Lead and As contents of the sulphides and secondary minerals overlap, and are generally positively correlated. Pyrite, the dominant sulphide in sulphidic schists associated with As-enriched groundwater in Coastal Maine, has values of 206Pb/204Pb from 18.186 to 18.391, 207Pb/204Pb from 15.617 to 15.657, 208Pb/204Pb from 38.052 to 38.210, 206Pb/207Pb from c. 1.1625 to 1.1760 and 208Pb/207Pb from c. 2.4276 to 2.4394. Mixtures of Fe-hydroxide and oxide minerals (predominantly goethite and hematite) and secondary Fe-sulphate minerals (jarosite, natrojarosite, rozenite and melanterite) in the sulphidic schists have overlapping but generally higher values of 206Pb/204Pb from 18.495 to 19.747 (one sample at 21.495), 207Pb/204Pb from 15.595 to 15.722 (one sample at 15.839), 208Pb/204Pb from 38.186 to 39.162,206Pb/207Pb from c.1.1860 to 1.2575 (one sample at 1.3855) and 208Pb/207Pb from c. 2.4441 to 2.4865 than the sulphides. Sulphides from Zn-Pb metal mines are somewhat less radiogenic than sulphides from the schists. Other sulphides (mostly pyrite) associated with pegmatites and granitic rocks are heterogeneous and more

  16. Unusual potential behavior for the weakly bound nucleus 9Be in elastic scattering from 208Pb and 209Bi near the threshold

    NASA Astrophysics Data System (ADS)

    Yu, N.; Zhang, H. Q.; Jia, H. M.; Zhang, S. T.; Ruan, M.; Yang, F.; Wu, Z. D.; Xu, X. X.; Bai, C. L.

    2010-07-01

    The elastic scattering angular distributions of the weakly bound 9Be projectile from 208Pb and 209Bi have been measured for 14 beam energies near the threshold from 37 to 50 MeV. The parameters of the optical potential are extracted by means of phenomenological optical model analysis with PTOLEMY. Both of the systems show unusual potential behavior in the vicinity of the Coulomb barrier that the strength of the imaginary (absorptive) part of the potential is increasing (rather than decreasing) with decreasing energy, which is quite different from the results of some previous reports. This unusual threshold phenomenon indicates that the breakup channel is strongly coupled with the elastic channel and has obvious effects on the optical potential. The analyses also show that high precision elastic scattering angular distributions, especially those below the Coulomb barrier, are very important for extracting correct threshold behavior of the optical potential.

  17. Investigation of the structure of deep hole states in {sup 90}Zr and {sup 208}Pb by means of inelastic proton scattering at 1 GeV

    SciTech Connect

    Vorob`ev, A.A.; Dotsenko, Yu.V.; Lobodenko, A.A.

    1995-11-01

    A missing-mass correlation spectrometer with overall energy resolution FWHM = 3.5 MeV is used to study the reactions (p, 2p) and (p, np) on {sup 90}Zr and {sup 208}Pb nuclei at energy T{sub 0} = 1.0 GeV under experimental conditions permitting complete kinematic reconstruction. Proton- and neutron-separation-energy spectra are obtained in a wide binding-energy range. Empirical regularities observed in the evolution of the principal parameters of deep hole states of protons and neutrons in going from light to heavy nuclei are discussed. Experimental data are analyzed by the Hartree-Fock method with Skyrme forces, as well as with modified Moszkowski {delta} interaction. 26 refs., 7 figs., 8 tabs.

  18. Energy dependence of the optical potentials for the 9Be +208Pb and 9Be +209Bi systems at near-Coulomb-barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Yu, N.; Zhang, H. Q.; Gomes, P. R. S.; Jia, H. M.; Lubian, J.; Lin, C. J.

    2015-04-01

    We analyze the energy dependence of the interacting optical potential, at near barrier energies, for two systems involving the weakly bound projectile 9Be and the heavy 208Pb and 209Bi targets, by the simultaneous fit of elastic scattering angular distributions and fusion excitation functions. The approach used consists of dividing the optical potential into two parts. A short-range potential VF+i WF that is responsible for fusion, and a superficial potential VDR+i WDR for direct reactions. It is found, for both systems studied, that the fusion imaginary potential WF presents the usual threshold anomaly (TA) observed in tightly bound systems, whereas the direct reaction imaginary potential WDR shows a breakup threshold anomaly (BTA) behavior. Both potentials satisfy the dispersion relation. The direct reaction polarization potential predominates over the fusion potential and so a net overall behavior is found to follow the BTA phenomenon.

  19. Study of two- and multi-particle correlations in 12C+24Mg and 12C+208Pb reactions at E=35 AMeV

    NASA Astrophysics Data System (ADS)

    Quattrocchi, L.; Acosta, L.; Amorini, F.; Anzalone, A.; Auditore, L.; Berceanu, I.; Cardella, G.; Chbihi, A.; De Filippo, E.; Dell'Aquila, D.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martel, I.; Minniti, T.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Veselsky, M.; Vigilante, M.

    2016-05-01

    Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30°) of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z˜3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

  20. Isotopic identification of natural vs. anthropogenic lead sources in marine sediments from the inner Ría de Vigo (NW Spain).

    PubMed

    Álvarez-Iglesias, P; Rubio, B; Millos, J

    2012-10-15

    San Simón Bay, the inner part of the Ría de Vigo (NW Spain), an area previously identified as highly polluted by Pb, was selected for the application of Pb stable isotope ratios as a fingerprinting tool in subtidal and intertidal sediment cores. Lead isotopic ratios were determined by inductively coupled plasma mass spectrometry on extracts from bulk samples after total acid digestion. Depth-wise profiles of (206)Pb/(207)Pb, (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb and (208)Pb/(207)Pb ratios showed, in general, an upward decrease for both intertidal and subtidal sediments as a consequence of the anthropogenic activities over the last century, or centuries. Waste channel samples from a nearby ceramic factory showed characteristic Pb stable isotope ratios different from those typical of coal and petrol. Natural isotope ratios from non-polluted samples were established for the study area, differentiating sediments from granitic or schist-gneiss sources. A binary mixing model employed on the polluted samples allowed estimating the anthropogenic inputs to the bay. These inputs represented between 25 and 98% of Pb inputs in intertidal samples, and 9-84% in subtidal samples, their contributions varying with time. Anthropogenic sources were apportioned according to a three-source model. Coal combustion-related emissions were the main anthropogenic source Pb to the bay (60-70%) before the establishment of the ceramic factory in the area (in the 1970s) which has since constituted the main source (95-100%), followed by petrol-related emissions. The Pb inputs history for the intertidal area was determined for the 20th century, and, for the subtidal area, the 19th and 20th centuries.

  1. Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments

    NASA Astrophysics Data System (ADS)

    Hu, Ningjing; Huang, Peng

    2016-04-01

    Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments Hu Ning-jinga, Huang Pengb,, Liu Ji-huaa, a First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China b Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China To investigate the source of Pb within Bohai Bay, Pb concentrations and Pb isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of surface sediments in this area were determined. The Pb concentration in this bay varied widely from 6.9 to 39.2 μg/g (average: 21.8 ± 7.8 μg/g), and the Pb isotopic compositions ranged from 0.8338 to 0.8864 (average: 2.0997 ± 0.0180) for 208Pb/206Pb and from 2.0797 to 2.1531 (average: 0.8477 ± 0.0135) for 207Pb/206Pb, presenting in three distinct clusters. The Pb isotopic ratios of sediments from the northeastern (NE zone) and northwestern (NW zone) coastal areas were significantly influenced by anthropogenic sources such as coal combustion and automobile emission. In sediments from the central and southern Bohai Bay (C-S zone); however, Pb mainly originated from the Yellow River catchment, as a result of lithogenic sediment (from rock weathering) accumulation. The Pb isotopic ratios further indicate that, apart from riverine inputs, the neighboring large-scale ports and aerosols significantly contributed to the anthropogenic Pb contained in these sediments. Pb contamination in the Haihe and Luanhe river mouths as well as in the regions near ports is also suggested from anthropogenic enrichment factors. As cities and ports continue to develop around Bohai Bay, a long-term extensive sewage monitoring program is highly recommended.

  2. Chemical signatures of the Anthropocene in the Clyde estuary, UK: sediment-hosted Pb, (207/206)Pb, total petroleum hydrocarbon, polyaromatic hydrocarbon and polychlorinated biphenyl pollution records.

    PubMed

    Vane, C H; Chenery, S R; Harrison, I; Kim, A W; Moss-Hayes, V; Jones, D G

    2011-03-13

    The sediment concentrations of total petroleum hydrocarbons (TPHs), polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), Pb and (207/206)Pb isotope ratios were measured in seven cores from the middle Clyde estuary (Scotland, UK) with an aim of tracking the late Anthropocene. Concentrations of TPHs ranged from 34 to 4386 mg kg(-1), total PAHs from 19 to 16,163 μg kg(-1) and total PCBs between less than 4.3 to 1217 μg kg(-1). Inventories, distributions and isomeric ratios of the organic pollutants were used to reconstruct pollutant histories. Pre-Industrial Revolution and modern non-polluted sediments were characterized by low TPH and PAH values as well as high relative abundance of biogenic-sourced phenanthrene and naphthalene. The increasing industrialization of the Clyde gave rise to elevated PAH concentrations and PAH isomeric ratios characteristic of both grass/wood/coal and petroleum and combustion (specifically petroleum combustion). Overall, PAHs had the longest history of any of the organic contaminants. Increasing TPH concentrations and a concomitant decline in PAHs mirrored the lessening of coal use and increasing reliance on petroleum fuels from about the 1950s. Thereafter, declining hydrocarbon pollution was followed by the onset (1950s), peak (1965-1977) and decline (post-1980s) in total PCB concentrations. Lead concentrations ranged from 6 to 631 mg kg(-1), while (207/206)Pb isotope ratios spanned 0.838-0.876, indicative of various proportions of 'background', British ore/coal and Broken Hill type petrol/industrial lead. A chronology was established using published Pb isotope data for aerosol-derived Pb and applied to the cores.

  3. Nuclear Volume Effects in Equilibrium Stable Isotope Fractionations of Hg, Tl and Pb Isotope Systems

    NASA Astrophysics Data System (ADS)

    Yang, S.; Liu, Y.

    2014-12-01

    Many evidences showed that heavy isotope systems could be significantly fractionated as the consequence of the nuclear volume effect (NVE) or so-called nuclear field shift effect. Here we investigate NVEs of Hg, Tl and Pb isotope systems by using quantum chemistry computational methods with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wavefunction. Our results generally agree with previous studies but with noticeable differences in many cases. With the unique NVE driving force, equilibrium 202Hg/198Hg and 205Tl/203Tl isotopes can be fractionated up to 3.94‰ and 2.78‰ at 0℃, respectively, showing potentially large equilibrium isotope fractionations can be expected for future studies of these two isotope systems. Moreover, the NVE causes large mass-independent fractionations (MIF) for odd-mass isotopes (e.g., ∆199NVHg and ∆201NVHg) and small MIFs for even-mass isotopes (e.g., ∆200NVHg). For Pb isotope system, NVEs induce isotope fractionations up to 1.62‰ (207Pb/206Pb) and 4.06‰ (208Pb/206Pb) at 0℃. However, contributions from classical mass-dependent driving force are small, about 0.1-0.5‰ for 207Pb/206Pb and 0.2-0.9‰ for 208Pb/206Pb. We find that Pb4+-bearing species can be significantly enriched heavy isotopes than Pb2+-bearing species. Comparing to Pb0, Pb2+-bearing species even enrich lighter Pb isotopes. A very strange and interesting thing is that the beta value of Pb2+-bearing species can be smaller than the unity (1.000). Similar thing has been found on Tl+-bearing species. This is an impossible and unexplained situation if only based on classical mass-dependent isotope fractionation theory (e.g., Bigeleisen-Mayer equation). The consequence is that the different direction of beta values of Pb2+-bearing species will let the Pb isotope fractionation even larger when they fractionate with Pb4+-bearing species. Moreover, NVEs also cause mass-independent fractionation (MIF) of odd 207Pb

  4. The study of neutron-rich nuclei production in the region of the closed shell N=126 in the multi-nucleon transfer reaction 136Xe+208Pb

    NASA Astrophysics Data System (ADS)

    Novikov, K.; Harca, I. M.; Kozulin, E. M.; Dmitriev, S.; Itkis, J.; Knyazheva, G.; Loktev, T.; Corradi, L.; Valiente-Dobon, J.; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Vardaci, E.; Quero, D.; Montagnoli, G.; Scarlassara, F.; Strano, E.; Pollarolo, G.; Piot, J.; Mijatović, T.; Szilner, S.; Ackermann, D.; Chubarian, G.; Trzaska, W. H.

    2016-04-01

    The unexplored area of heavy neutron rich nuclei is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleogenesis. For the production of heavy neutron rich nuclei located along the neutron closed shell N=126 (probably the last "waiting point" in the r-process of nucleosynthesis) the low-energy multi-nucleon transfer reaction 136Xe+208Pb at Elab=870MeV was explored. Due to the stabilizing effect of the closed neutron shells in both nuclei, N=82 and N=126, and the rather favorable proton transfer from lead to xenon, the light fragments formed in this process are well bound and the Q-value of the reaction is nearly zero. Measurements were performed with the PRISMA spectrometer in coincidence with an additional time-of-flight (ToF) arm on the +20 beam line of the PIAVE-ALPI accelerator in Legnaro, Italy. The PRISMA spectrometer allows identification of the A, Z and velocity of the projectile-like fragments (PLF), while the second arm gives access to the target-like fragments (TLF). Details on the experimental setup and preliminary results are reported.

  5. Excitation function for the production of {sup 262}Bh (Z=107) in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n)

    SciTech Connect

    Folden, C.M. III; Nelson, S.L.; Duellmann, Ch.E.; Schwantes, J.M.; Zielinski, P.M.; Nitsche, H.; Hoffman, D.C.; Sudowe, R.; Gregorich, K.E.

    2006-01-15

    The excitation function for production of {sup 262}Bh in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from {sup 262}Bh and 2 decay chains originating from {sup 261}Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540{sub -150}{sup +180} pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than five times larger than that expected based on previously reported results for production of {sup 262}Bh in the analogous even-Z-projectile reaction {sup 209}Bi({sup 54}Cr, n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the optimum energy rule proposed by SwiaPtecki, Siwek-Wilczynska, and Wilczynski.

  6. Excitation function for the production of 262Bh (Z = 107) in theodd-Z projectile reaction 208Pb(55Mn, n)

    SciTech Connect

    Folden III, C.M.; Nelson, S.L.; Dullmann, Ch.E.; Schwantes, J.M.; Sudowe, R.; Zielinski, P.M.; Gregorich, K.E.; Nitsche, H.; Hoffman, D.C.

    2005-05-16

    The excitation function for production of 262Bh in the odd-Z-projectile reaction 208Pb(55Mn,n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from 262Bh and 2 decay chains originating from 261Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540 +180 - 150 pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than fives times larger than that expected based on previously reported results for production of 262Bh in the analogous even-Z-projectile reaction 209Bi(54Cr,n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the ''Optimum Energy Rule'' proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski.

  7. In-situ U/Pb rutile dating by LA-ICP-MS: 208Pb correction and prospects for thermochronological applications

    NASA Astrophysics Data System (ADS)

    Zack, T.; Stockli, D. F.; Luvizotto, G. L.; Barth, M. G.; Wolfe, M. R.; Hinton, R. W.; Berndt-Gerdes, J.; Kooijman, E.

    2009-12-01

    The advent of rutile thermometry brought an increasing interest in understanding rutile formation and its temporal evolution. Here we report progress on several fronts of in situ U-Pb rutile geochronology: (1) Matrix matching, necessary for robust in situ dating is fullfilled by calibrating and testing rutile standards (R10 and R19), including the presentation of new TIMS ages for the rutile standard R19. (2) Common lead correction is routinely applied via 208Pb, which is possible due to extremely low Th/U ratios (usually <0.003) in most rutiles. Employing a 213 nm Nd:YAG laser coupled to a quadrupole ICP-MS and using R10 as a primary standard, rutile U/Pb ages for the other rutile standard and four rutile-bearing metamorphic rocks always agree better than 2% with the reported TIMS ages and other dating studies from the same localities. The methods outlined in this contribution should find wide application in thermochronological studies that require age information of single spots, e.g., single-crystal zoning and texturally-controlled dating. With this information we are able to address the effect of shielding of inclusion phases by robust host minerals.

  8. Mass, total kinetic energy, and neutron multiplicity correlations in the binary fragmentation of +208Pb 50Ti at 294 MeV bombarding energy

    NASA Astrophysics Data System (ADS)

    Appannababu, S.; Cinausero, M.; Marchi, T.; Gramegna, F.; Prete, G.; Bermudez, J.; Fabris, D.; Collazuol, G.; Saxena, A.; Nayak, B. K.; Kailas, S.; Bruno, M.; Morelli, L.; Gelli, N.; Piantelli, S.; Pasquali, G.; Barlini, S.; Valdré, S.; Vardaci, E.; Sajo-Bohus, L.; Degerlier, M.; Jhingan, A.; Behera, B. R.; Kravchuk, V. L.

    2016-10-01

    The correlations between mass distributions of the binary fragments, total kinetic energy (TKE), and neutron multiplicity have been investigated for the reaction +208Pb 50Ti at 294 MeV bombarding energy. Although this reaction has been used to synthesize the Rf (Z =104 ) superheavy element, a complete study of its fragmentation dynamics is still not available in the literature. In this work, average neutron multiplicities were extracted as a function of different fragment mass splits and TKE windows. A weak increase of the prescission neutron multiplicity is observed going from asymmetric to symmetric mass splits. A fission delay time of 4.5 ×10-20 s has been extracted for the symmetric fission. The neutron multiplicity extracted for the symmetric mass split was used to derive the average number of neutrons emitted in the spontaneous fission of 258Rf. The extrapolated value of 4.7 ±1.4 is found to be consistent with systematics of spontaneous and neutron-induced fission in heavy nuclei and with the results of previous works for superheavy nuclei with Z =116 and Z =124 .

  9. Comparison of reactions for the production of 258,257Db: 208Pb(51V,xn) and 209Bi(50Ti,xn)

    SciTech Connect

    Gates, Jacklyn M.; Nelson, Sarah L.; Gregorich, Kenneth E.; Dragojevic, Irena; Dullmann, Christoph E.; Ellison, Paul A.; Folden III, Charles M.; Garcia, Mitch A.; Stavsetra, Liv; Sudowe, Ralf; Hoffman, Darleane C.; Nitsche, Heino

    2008-09-29

    Excitation functions for the 1n and 2n exit channels of the 208Pb(51V,xn)259-xDb reaction were measured. A maximum cross section of the 1n exit channel of 2070+1100/-760 pb was measured at an excitation energy of 16.0 +- 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660+450/-370 pb was measured at 22.0 +- 1.8 MeV excitation energy. The 1n excitation function for the 209Bi(50Ti,n)258Db reaction was remeasured, resulting in a cross section of 5480+1750/-1370 pb at an excitation energy of 16.0 +- 1.6 MeV, in agreement with previous values [F. P. Hebberger, et al., Eur. Phys. J. A 12, 57 (2001)]. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.

  10. Identification of trace metal pollution in urban dust from kindergartens using magnetic, geochemical and lead isotopic analyses

    NASA Astrophysics Data System (ADS)

    Zhu, Zongmin; Sun, Guangyi; Bi, Xiangyang; Li, Zhonggen; Yu, Genhua

    2013-10-01

    In the present study, magnetic measurements were combined with geochemical analysis and stable Pb isotopic ratios to reveal the distribution and origination of trace metal pollutants in kindergarten dusts from a typical urban environment of Wuhan, central China. The geoaccumulation index (Igeo) of magnetic properties was more prominent than those of individual metals. The magnetic susceptibility (MS) and trace metals (Zn, Pb, and Cu) in this study together with published results from other Chinese cities formed a liner relationship, suggesting that metal contaminants in Chinese urban areas had similar MS to metal ratios, which could be used as an indicator for identification of pollution sources between Chinese cities and the other Asian cities. Stable Pb isotopic ratios (1.1125-1.1734 for 206Pb/207Pb and 2.4457-2.4679 for 208Pb/207Pb) in the urban dusts from Wuhan were characterized by higher 208Pb component in comparison with those from other Chinese cities. This result combined with principal component analysis (PCA) indicated that metal pollutants in the dusts were derived from industrial activities and coal combustion, whereas the traffic emissions were no longer a predominant pollution source in urban environment. Our study demonstrated that environmental magnetic methods could not only reveal the overall situation of trace metal contamination, but also prove evidence in the identification of pollution sources.

  11. Stable lead isotopic ratios trace thermohaline circulation in the subarctic North Atlantic

    NASA Astrophysics Data System (ADS)

    Véron, A. J.; Church, T. M.; Rivera-Duarte, I.; Flegal, A. R.

    Vertical profiles of lead concentrations in the subarctic North Atlantic attest to the predominance of anthropogenic lead inputs to those waters, while variations in their lead isotopic ratios ( 204Pb : 206Pb : 207Pb : 208Pb) show the multiplicity of those industrial lead inputs. Spatial gradients in the isotopic ratios are consistent with the thermohaline circulation of different water masses, which seemingly have relatively discrete isotopic signatures. These include characteristic 206Pb/ 207Pb ratios of the North Atlantic Drift (1.183-1.187), Iceland-Scotland Overflow Water (1.173-1.176), Denmark Straits Overflow Water (1.179-1.182), and Labrador Sea Water (1.190-1.120). Based on parallels between these initial isotopic data and T- S measurements, it is proposed that stable lead isotopic compositions may be employed as complementary tracers of the mixing of source waters in the Nordic seas, as they overflow the Iceland-Scotland Ridge and Denmark Strait, mixing into the Labrador Sea to form North Atlantic Deep Water.

  12. The Condor seamount at Mid-Atlantic Ridge as a supplementary source of trace and rare earth elements to the sediments

    NASA Astrophysics Data System (ADS)

    Caetano, Miguel; Vale, Carlos; Anes, Bárbara; Raimundo, Joana; Drago, Teresa; Schimdt, Sabine; Nogueira, Marta; Oliveira, Anabela; Prego, Ricardo

    2013-12-01

    The Condor Seamount rises from seabed to 180m water depth, being located 10 nautical miles southwest of the island of Faial, Azores Archipelago at the Mid-Atlantic Ridge (MAR). The vertical distribution of major, minor, trace and rare earth elements (REE) and Pb isotopes was studied in four sediment cores: one from the top of the Condor Seamount (200m, MC9), two from the seamount base (1400m, MC2 and MC4), and one from a deep area (1900m, MC8). Sediments from the top of the Condor were composed by coarser particles being the fine fraction lower than 1%. Conversely the other sediments were constituted by 51-92% of fine particles (<63μm). Individual fragments of volcanic material (>2mm) were found at several depths of the cores sampled at the base of the seamount. The core collected in the top of the Condor showed higher carbonate content (76-86%) compared with the other cores (41-64%). The chemical compositions of MC2 and MC4 point to an enhancement of V, Cr, Co, Ni and Fe concentrations. Lower concentrations in MC8 hypothesis that Condor seamount constitutes a supplementary source of trace elements. The most plausible explanation for the enhancement found in sediments of the seamount base is the weathering of slopes with volcanic activities, which supply particles with higher element concentrations than pelagic sediments. This hypothesis is corroborated by REE data, showing increased chondrite normalized ratios in MC2 and MC4. Moreover, the REE pattern found in those cores was comparable to that existing in volcanic material with Light REE enrichment in comparison to Heavy REE. These results indicate a substantial contribution of particles derived from volcanic activities to sediments settled in the vicinity of the Condor Seamount. It is argued the potential use of REE in sediments from this region as tracers of volcanic activities. Depth profiles of 206Pb/207Pb and 206Pb/208Pb showed lower ratios in the first 8cm sediment layers, reflecting atmospheric input of

  13. Natural radionuclide mobility and its influence on U-Th-Pb dating of secondary minerals from the unsaturated zone at Yucca Mountain, Nevada

    USGS Publications Warehouse

    Neymark, L.A.; Amelin, Y.V.

    2008-01-01

    Extreme U and Pb isotope variations produced by disequilibrium in decay chains of 238U and 232Th are found in calcite, opal/chalcedony, and Mn-oxides occurring as secondary mineral coatings in the unsaturated zone at Yucca Mountain, Nevada. These very slowly growing minerals (mm my-1) contain excess 206Pb and 208Pb formed from excesses of intermediate daughter isotopes and cannot be used as reliable 206Pb/238U geochronometers. The presence of excess intermediate daughter isotopes does not appreciably affect 207Pb/235U ages of U-enriched opal/chalcedony, which are interpreted as mineral formation ages. Opal and calcite from outer (younger) portions of coatings have 230Th/U ages from 94.6 ?? 3.7 to 361.3 ?? 9.8 ka and initial 234U/238U activity ratios (AR) from 4.351 ?? 0.070 to 7.02 ?? 0.12, which indicate 234U enrichment from percolating water. Present-day 234U/238U AR is ???1 in opal/chalcedony from older portions of the coatings. The 207Pb/235U ages of opal/chalcedony samples range from 0.1329 ?? 0.0080 to 9.10 ?? 0.21 Ma, increase with microstratigraphic depth, and define slow long-term average growth rates of about 1.2-2.0 mm my-1, in good agreement with previous results. Measured 234U/238U AR in Mn-oxides, which pre-date the oldest calcite and opal/chalcedony, range from 0.939 ?? 0.006 to 2.091 ?? 0.006 and are >1 in most samples. The range of 87Sr/86Sr ratios (0.71156-0.71280) in Mn-oxides overlaps that in the late calcite. These data indicate that Mn-oxides exchange U and Sr with percolating water and cannot be used as a reliable dating tool. In the U-poor calcite samples, measured 206Pb/207Pb ratios have a wide range, do not correlate with Ba concentration as would be expected if excess Ra was present, and reach a value of about 1400, the highest ever reported for natural Pb. Calcite intergrown with opal contains excesses of both 206Pb and 207Pb derived from Rn diffusion and from direct ??-recoil from U-rich opal. Calcite from coatings devoid of opal

  14. Allanite from the El Muerto Pegmatite, Oaxaca, Mexico: A Potential New Standard for 232Th-208Pb Dating by LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Price, J.; Crowley, J. L.; Solari, L.; Prol-Ledesma, R.

    2012-12-01

    Allanite dating may be important to studies addressing tectonomagmatic evolution, provenance of monocyclic sediment, and mineral weathering. Obtaining accurate allanite ages by SIMS has been challenging and time-consuming due to the mineral's extreme chemical variability which often prevents finding adequately matrix-matched standards. Isotopic measurements by LA-ICP-MS minimize the need for standards of nearly identical composition to the unknown allanite being analyzed, and it is done relatively rapidly. Dating by LA-ICP-MS requires high quality standards for isotopic fractionation corrections. However, readily accessible and well characterized allanite standards are scarce. We investigated gemstone allanite from the El Muerto pegmatite, Oaxaca, Mexico, as a potential new geochronology standard for 232Th-208Pb allanite dating by LA-ICP-MS. Compositional homogeneity was thoroughly investigated by scanning and backscatter electron microscopy, cathodoluminescence, quantitative and qualitative energy dispersive x-ray spectroscopy, electron microprobe, and LA-ICP-MS. The possibility of metamictization was investigated by extensive X-ray diffraction analyses. The El Muerto allanite was U-Pb dated by ID-TIMS, with common Pb ratios determined from cogenetic K-feldspar by ID-TIMS and LA-MC-ICP-MS. Future work includes Th-Pb dating by ID-TIMS. The samples investigated are homogeneous with respect to major and trace elements. Major element compositional results are generally in agreement with published values, and no metamictization was identified despite the allanite being nearly 1 Ga. The only limitation of the El Muerto allanite is that it contains small, generally <100 μm, scarce inclusions of quartz, calciothorite, albite, calcite, and biotite. However, these grains are easily recognized and avoided during LA-ICP-MS analyses. Based on these results, the El Muerto allanite has the potential to serve as a standard for LA-ICP-MS dating.

  15. Uptake and recycling of lead by boreal forest plants: Quantitative estimates from a site in northern Sweden

    NASA Astrophysics Data System (ADS)

    Klaminder, Jonatan; Bindler, Richard; Emteryd, Ove; Renberg, Ingemar

    2005-05-01

    As a consequence of deposition of atmospheric pollution, the lead concentration in the mor layer (the organic horizon) of remote boreal forest soils in Sweden is raised far above natural levels. How the mor will respond to decreased atmospheric pollution is not well known and is dependent on future deposition rates, downward migration losses and upward fluxes in the soil profile. Plants may contribute to the upward flux of lead by 'pumping' lead back to the mor surface through root uptake and subsequent litter fall. We use lead concentration and stable isotope ( 206Pb, 207Pb and 208Pb) measurements of forest vegetation to quantify plant uptake rates from the soil and direct from the atmosphere at two sites in northern Sweden; an undisturbed mature forest and a disturbed site with Scots pine ( Pinus sylvestris) growing on a recently exposed mineral soil (C-horizon) containing a minimum of atmospherically derived pollution lead. Analyses of forest mosses from a herbarium collection (spanning the last ˜100 yr) and soil matrix samples suggest that the atmospheric lead deposited on plants and soil has an average 206Pb/ 207Pb ratio of 1.15, while lead derived from local soil minerals has an average ratio of ˜1.47. Since the biomass of trees and field layer shrubs has an average 206Pb/ 207Pb ratio of ˜1.25, this indicates that 70% ± 10% of the inventory of 1 ± 0.8 mg Pb m -2 stored in plants in the mature forest originates from pollution. Needles, bark and apical stemwood of the pine growing on the disturbed soil, show lower 206Pb/ 207Pb ratios (as low as 1.21) than the roots and basal stemwood (having ratios > 1.36), which indicate that plants are able to incorporate lead directly from the atmosphere (˜50% of the total tree uptake). By partitioning the total uptake of lead into uptake from the atmosphere and different soil layers using an isotopic mixing model, we estimate that ˜0.03 ± 0.01, 0.02 ± 0.01 and 0.05 ± 0.01 mg Pb m -2 yr -1 (mean ± SD), is taken up

  16. Isotopic composition of Pb in ore deposits of the Betic Cordillera, Spain; origin and relationship to other European deposits

    USGS Publications Warehouse

    Arribas , Antonio; Tosdal, Richard M.

    1994-01-01

    The Betic Cordillera in southern Spain is a complex Alpine fold belt that resulted from the Cretaceous through Cenozoic collision of Africa with Europe. The region is illustrative of one of the characteristics of the Alpine-Mediterranean orogen: the occurrence over a limited area of mineral deposits with a wide variety of host rocks, mineralization ages, and styles. The metamorphic basement in the Betic zone is characterized by a nappe structure of superimposed tectonostratigraphic units and consists of lower Paleozoic to Lower Triassic clastic metasedimentary rocks. This is overlain by Middle to Upper Triassic platform carbonate rocks with abundant strata-bound F-Pb-Zn-(Ba) deposits (e.g., Sierra de Gador, Sierra Alhamilla). Cretaceous to Paleogene subduction-related compression in southeastern Spain was followed by Miocene postcollisional extension and resulted in the formation of the Almeria-Cartagena volcanic belt and widespread hydrothermal activity and associated polymetallic mineralization. Typical Miocene hydrothermal deposits include volcanic-hosted Au (e.g., Rodalquilar) and Ag-rich base metal (e.g., Cabo de Gata, Mazarron) deposits as well as complex polymetallic veins, mantos, and irregular replacement bodies which are hosted by Paleozoic and Mesozoic metamorphic rocks and Neogene sedimentary and volcanic rocks (e.g., Cartagena, Sierra Almagrera, Sierra del Aguilon, Loma de Bas).Lead isotope compositions were measured on sulfide samples from nine ore districts and from representative fresh samples of volcanic and basement rock types of the region. The results have been used to evaluate ore-forming processes in southeastern Spain with emphasis on the sources of metals. During a Late Triassic mineralizing event, Pb was leached from Paleozoic clastic metasedimentary rocks and incorporated in galena in strata-bound F-Pb-Zn-(Ba) deposits ( 206 Pb/ 204 Pb = 18.332 + or - 12, 207Pb/ 204 Pb = 15.672 + or - 12, 208 Pb/ 204 Pb = 38.523 + or - 46). The second

  17. Fast and precise method for Pb isotope ratio determination in complex matrices using GC-MC-ICPMS: application to crude oil, kerogen, and asphaltene samples.

    PubMed

    Sanabria-Ortega, Georgia; Pécheyran, Christophe; Bérail, Sylvain; Donard, Olivier F X

    2012-09-18

    A new method to determine Pb isotope ratio without ion-exchange-matrix separation is proposed. After acid digestion, Pb was ethylated to Et(4)Pb, separated from the digested solution (black shale, asphaltene, crude oil and kerogen) by extraction in isooctane, and then injected into a gas chromatograph coupled to a multicollector inductively coupled plasma mass spectrometer. Seven isotopes ((202)Hg, (203)Tl, (204)Pb, (205)Tl, (206)Pb, (207)Pb, (208)Pb) were monitored simultaneously with peak duration of 23 s. GC elution was operated under wet plasma conditions where a thallium standard solution was introduced to the mass spectrometer for mass bias correction. The total time of the procedure (sample preparation and analysis, after acid digestion) was reduced by a factor of 15 compared to conventional-continuous sample introduction. Data treatment was carried out using the linear regression slope method. Mass bias was corrected using the double correction method (first thallium normalization followed by classical bracketing). For the (208/206)Pb and (207/206)Pb ratios, precision (2RSD(EXT), n = 21) was 49 and 69 ppm, and the bias between experimental results and reference values was better than 0.0033 and 0.0007 ‰, when injecting 1.2 ng of ethylated Pb SRM NIST 981 solution. Results obtained by this method were validated by comparison with those obtained via conventional-continuous sample introduction. The applicability of this approach was demonstrated with the analysis of black shale, asphaltene, crude oil and kerogen samples.

  18. Lead isotopes and trace metal ratios of aerosols as tracers of Pb pollution sources in Kanpur, India

    NASA Astrophysics Data System (ADS)

    Sen, Indra; Bizimis, Michael; Tripathi, Sachchida; Paul, Debajyoti; Tyagi, Swati; Sengupta, Deep

    2015-04-01

    The anthropogenic flux of Pb in the Earth's surface is almost an order of magnitude higher than its corresponding natural flux [1]. Identifying the sources and pathways of anthropogenic Pb in environment is important because Pb toxicity is known to have adverse effects on human health. Pb pollution sources for America, Europe, and China are well documented. However, sources of atmospheric Pb are unknown in India, particularly after leaded gasoline was phased out in 2000. India has a developing economy with a rapidly emerging automobile and high temperature industry, and anthropogenic Pb emission is expected to rise in the next decade. In this study, we report on the Pb- isotope compositions and trace metal ratios of airborne particulates collected in Kanpur, an industrial city in northern India. The Pb concentration in the airborne particulate matter varies between 14-216 ng/m3, while the other heavy metals vary by factor of 10 or less, e.g. Cd=0.3-3 ng/m3, As=0.4-3.5 ng/m3, Zn=36-161 ng/m3, and Cu=3-22 ng/m3. The 206Pb/207Pb, 208Pb/206Pb, and 208Pb/207Pb vary between 1.112 - 1.129, 2.123-2.141, and 2.409-2.424 respectively, and are highly correlated with each other (R2>0.9). Pb isotopes and trace metal data reveals that coal combustion is the major source of anthropogenic Pb in the atmosphere, with limited contribution from mining and smelting processes. We further conclude that combination of Pb isotope ratios and V/Pb ratios are powerful tracers for Pb source apportionment studies, which is otherwise difficult to differentiate based only on Pb systematics [1] Sen and Peucker-Ehrenbrink (2012), Environ. Sci. Technol.(46), 8601-8609

  19. Spatial and temporal evolution of lead isotope ratios in the North Atlantic Ocean between 1981 and 1989

    NASA Astrophysics Data System (ADS)

    Weiss, Dominik; Boyle, Edward A.; Wu, Jingfeng; Chavagnac, ValéRie; Michel, Anna; Reuer, Matthew K.

    2003-10-01

    /tropical surface water exchanges. Triple-isotope plots (206Pb, 207Pb, and 208Pb) suggest that most of the lead can be accounted for by wet aerosol deposition derived from the adjacent landmasses of America to the west (transported via the North American Westerlies) and from Europe to the east (transported via the European Easterlies) and probably by some advected surface waters from the Sargasso Sea. The 1989 triple-isotope plot suggests, however, a third lead source in the subtropical western North Atlantic, possibly leaded gasoline from Mexico. Gasoline lead emission patterns as well as atmospheric lead isotope signatures confirm that gasoline was the main pollutant source in the early 1980s but suggest that contributions from high-temperature industrial processes (coal combustion, steel manufacture, waste incineration) have been increasing in the late 1980s. From isotopic mass balance estimates, lead inputs to the 1980s North Atlantic were dominated by North American sources (>53%). These elemental and isotopic results demonstrate the strongly variable isotopic and elemental signatures of North American and European lead throughout the North Atlantic Ocean, frequently dominated by high 206Pb/207Pb and [Pb] North American signatures throughout the subtropical North Atlantic gyre.

  20. Plume-Lithosphere Interaction beneath the Snake River Plain, Idaho: Constraints from Pb, Sr, Nd, and Hf Isotopes

    NASA Astrophysics Data System (ADS)

    Jean, M. M.; Hanan, B. B.; Shervais, J. W.

    2011-12-01

    The Yellowstone-Snake River Plain (YSRP) volcanic province links 17 million years of volcanic activity that extends from the Owyhee Plateau in western Idaho/eastern Oregon to its current terminus underlying the Yellowstone Plateau. This investigation presents new Strontium, Neodymium, Lead, and Hafnium isotopic compositions of 25 basalts that represent four distinct areas of the YSRP (i.e., eastern province, central province, western province, Owyhee Plateau), which transect the ancient cratonic boundary of North America. The purpose of this study is to test and refine models for plume-lithosphere interaction and determines the mantle origin for YSRP basalts. New results shows: (1) low-K tholeiites from the eastern, central, and western SRP have ɛNd (-2 to -5.5), 87Sr/86Sr (0.7060-0.7071) and similar Pb-isotopes [206Pb/204Pb (17.8-18.6), 207Pb/204Pb (15.5-15.66), 208Pb/204Pb (38.4-39.1)]; (2) central SRP tholeiites are enriched in 208Pb/204Pb (~38.5-38.9), relative to eastern SRP basalts and define a 208Pb/204Pb trend, intermediate between the eastern SRP and Craters of the Moon lavas; (3) western SRP high-K basalts are depleted in ɛNd (> -1) and 87Sr/86Sr (0.7050-0.7057), relative to low-K tholeiites, and plot closer to "bulk silicate earth," but are enriched in 206Pb/204Pb (18.66-18.71), and have 207Pb/204Pb (15.62-15.65) and 208Pb/204Pb (39.1-39.2) isotope ratios similar to high-K basalts of Smith Prairie (Boise River Group 2); (4) Silver City basalt (>16.6 Ma) overlaps in Pb-isotope space with Imnaha basalt compositions (Columbia River Basalt Group); (5) new 177Hf/176Hf isotopic data lie above and parallel to the Mantle array in Nd and Hf isotope space and define a linear trend between Leucite Hills lavas and OIB basalts (i.e., Steens and Hawaii); (6) these basalts follow a systematic geographic pattern: eastern and central plain low-K tholeiites have low ɛNd (-3 to -5) and intermediate 206Pb/204Pb (~17.7-18.5), while western plain low-K tholeiites are

  1. Doorway-state analysis of the fine structure in the giant quadrupole resonance in 208Pb observed in inelastic electron scattered

    NASA Astrophysics Data System (ADS)

    Winchenbach, J.; Pingel, K.; Holzwarth, G.; Kühner, G.; Richter, A.

    1983-11-01

    The fine structure observed in high resolution inelastic electron scattering data obtained at DALINAC for 208Pb in the excitation energy range of the giant quadrupole resonance (GQR) has been analysed under the assumption that the measured strongly fragmented E2 strength distribution is due to the coupling of one or two doorway states to a large number of more complicated states. The coupling matrix elements derived from the analysis allow the determination of the escape and spreading widths Γ ↑ and Γ ↓, the excitation energies Ed, the energy shifts ΔEd, and their energy dependence, for the underlying doorways.

  2. Accumulation and quantitative estimates of airborne lead for a wild plant (Aster subulatus).

    PubMed

    Hu, Xin; Zhang, Yun; Luo, Jun; Xie, Mingjie; Wang, Tijian; Lian, Hongzhen

    2011-03-01

    Foliar uptake of airborne lead is one of the pathways for Pb accumulation in plant organs. However, the approximate contributions of airborne Pb to plant organs are still unclear. In the present study, aerosols (nine-stage size-segregated aerosols and total suspended particulates), a wild plant species (Aster subulatus) and the corresponding soils were collected and Pb contents and isotopic ratios in these samples were analyzed. Average concentration of Pb was 96.5 ± 63.5 ng m(-3) in total suspended particulates (TSP) and 20.4 ± 5.5 ng m(-3) in the fine fractions of size-segregated aerosols (SSA) (<2.1 μm), higher than that in the coarser fractions (>2.1 μm) (6.38 ± 3.71 ng m(-3)). Enrichment factors show that aerosols and soils suffered from anthropogenic inputs and the fine fractions of the size-segregated aerosols enriched more Pb than the coarse fractions. The order of Pb contents in A. subulatus was roots>leaves>stems. The linear relationship of Pb isotope ratios ((206)Pb/(207)Pb and (208)Pb/(206)Pb) among soil, plant and aerosol samples were found. Based on the simple binary Pb isotopic model using the mean (206)Pb/(207)Pb ratios in TSP and in SSA, the approximate contributions of airborne Pb into plant leaves were 72.2% and 65.1%, respectively, suggesting that airborne Pb is the most important source for the Pb accumulation in leaves. So the combination of Pb isotope tracing and the simple binary Pb isotope model can assess the contribution of airborne Pb into plant leaves and may be of interest for risk assessment of the exposure to airborne Pb contamination.

  3. Temporal trends of pollution Pb and other metals in east-central Baffin Island inferred from lake sediment geochemistry.

    PubMed

    Michelutti, Neal; Simonetti, Antonio; Briner, Jason P; Funder, Svend; Creaser, Robert A; Wolfe, Alexander P

    2009-10-15

    Concentrations and stable isotope ratios of lead (Pb) from lake sediments were used to quantify temporal patterns of anthropogenic Pb pollution in the Clyde River region of Baffin Island, Arctic Canada. Surface sediments from eight lakes on eastern Baffin Island and one from northern-most Greenland, spanning a gradient of 20 degrees latitude, showed great variability with respect to Pb concentration and stable isotopic Pb ratios, with little apparent latitudinal trend. To constrain the temporal evolution of regional Pb pollution, a well-dated core from one of the sites, Lake CF8 on east-central Baffin Island, was analyzed geochemically at high stratigraphic resolution. A pronounced decrease in the (206)Pb/(207)Pb ratio occurs in sediments deposited between 1923 and the mid-1970s, likely reflecting alkyl-Pb additives derived from the combustion of fossil fuels at a global scale. A two-component mixing model indicates that 17-26% of the Pb in the labile fraction of sediments deposited in Lake CF8 between 2001 and 2005 is from anthropogenic input. A Pb-Pb co-isotopic plot ((206)Pb/(207)Pb vs.(208)Pb/(206)Pb ratios) of the Lake CF8 time series data indicates multiple possible sources of industrial Pb pollution. Despite widespread reductions in industrial Pb emissions since the 1970s, there is no evidence for attendant reductions of pollution Pb at Lake CF8. Enhanced scavenging from increased primary production as well as changing precipitation rates as climate warms may represent important factors that modulate Pb deposition to Lake CF8, and Arctic lakes elsewhere.

  4. Time differences in the formation of meteorites as determined from the ratio of lead-207 to lead-206

    USGS Publications Warehouse

    Tatsumoto, M.; Knight, R.J.; Allegre, C.J.

    1973-01-01

    Measurements of the lead isotopic composition and the uranium, thorium, and lead concentrations in meteorites were made in order to obtain more precise radiometric ages of these members of the solar system. The newly determined value of the lead isotopic composition of Canyon Diablo troilite is as follows: 206Pb/204Pb = 9.307, 207Pb/204Pb = 10.294, and 208Pb/204Pb = 29.476. The leads of Angra dos Reis, Sioux County, and Nuevo Laredo achondrites are very radiogenic, the 206Pb/204Pb values are about 200, and the uranium-thorium-lead systems are nearly concordant. The ages of the meteorites as calculated from a single-stage 207Pb/206Pb isochron based on the newly determined primordial lead value and the newly reported 235U and 238U decay constants, are 4.528 ?? 10 9 years for Sioux County and Nuevo Laredo and 4.555 ?? 10 9 years for Angra dos Reis. When calculated with the uranium decay constants used by Patterson, these ages are 4.593 ?? 109 years and 4.620 ?? 109 years, respectively, and are therefore 40 to 70 ?? 106 years older than the 4.55 ?? 109 years age Patterson reported. The age difference of 27 ?? 106 years between Angra dos Reis and the other two meteorites is compatible with the difference between the initial 87Sr/86Sr ratio of Angra dos Reis and that of seven basaltic achondrites observed by Papanastassiou and Wasserburg. The time difference is also comparable to that determined by 129I-129Xe chronology. The ages of ordinary chondrites (H5 and L6) range from 4.52 to 4.57 ?? 109 years, and, here too, time differences in the formation of the parent bodies or later metamorphic events are indicated. Carbonaceous chondrites (C2 and C3) appear to contain younger lead components.

  5. U-Th-Pb ion microprobe analysis of monazite from the Paleoproterozoic Karrat rare earth element (REE) deposit, western Greenland

    NASA Astrophysics Data System (ADS)

    Mott, A.; Grove, M.; Bird, D. K.

    2012-12-01

    The Karrat rare earth element (REE) deposit is located at 72°N on the Niaqornakavsak peninsula of Qeqertarssuq Island on the western coast of Greenland. Metasomatic alteration of an amphibolite host rock by carbonatite derived fluids resulted in REE mineralization in the Karrat Isfjord area. REE in the mineralization are primarily found in bastnasite, allanite, and monazite. In-situ analysis of monazite was conducted on samples obtained from three sites of mineralization: (1) the primary deposit at Niaqornakavsak consisting of a single distinct ~30m thick unit; (2) at Umiamako Nuna 7 km to the east of Niaqornakavsak where the majority of REE mineralization occurs within the first 20m of the surface; and (3) a 6m thick REE-rich vein 100m below the surface at Umiamako Nuna. Formation ages for monazite at Niaqornakavsak, Umiamako Nuna (surface), and Umiamako Nuna (vein) have been calculated using 207Pb/206Pb, 206Pb/238U, and 208Pb/232Th isotope ratios. Multiple isotope ratios were examined to determine the ideal method of monazite analysis based on the inherent issues of low U content of monazite, difficulties measuring 204Pb, common Pb corrections, and peak interferences resulting from high concentrations of REE. 208Pb/232Th analysis resulted in the best precision and smallest spread of values. Energy filtering was applied to 208Pb/232Th analyses in an effort to reduce interferences at several peaks. Although all three isotope ratio analyses result in a Paleoproterozoic age similar to the timing of convergence of the North Atlantic craton, Rae craton, and Aasiat domain as well as the emplacement of the Prøven Igneous Complex in Greenland (1.95-1.80Ga), the values range between 1.7-1.9Ga depending on the isotope ratio.

  6. The transfer of bomb radiocarbon and anthropogenic lead to the deep North Atlantic Ocean observed from a deep sea coral

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Mi; Eltgroth, Selene F.; Boyle, Edward A.; Adkins, Jess F.

    2017-01-01

    Deep-ocean, Δ14C, Pb concentrations, and Pb isotopes were reconstructed from a deep-sea coral Enallopsammia rostrata from 1410 m depth off of Bermuda. Our high-resolution time series is created from closely spaced radial cross sections, with samples taken from the center of concentric coral growth bands that we show to be the oldest portion of the section. Prebomb radiocarbon ages from the coral demonstrate that the vertical growth rate of the coral is linear, and the age of the coral is estimated to be 560-630 yr old based on the growth rate. Using this age model to reconstruct Δ14C in deep seawater, we first detect bomb radiocarbon at the coral growth site around 1980, and show that Δ14C increased from - 80 ± 1 ‰ (average 1930-1979) to a plateau at - 39 ± 3 ‰ (1999-2001). Pb/Ca of the coral ranges between 1.1-4.5 nmol/mol during the 16th and 17th centuries, and Pb isotope ratios (206Pb/207Pb = 1.21, 208Pb/207Pb = 2.495) in this period agree with pre-anthropogenic values found in the pelagic sediments of the North Atlantic Ocean basin. Coral Pb/Ca is slightly elevated to 6.2 ± 0.9 nmol /mol between the 1740s and the 1850s and then increases to 25.1 ± 0.2 nmol /mol in the 1990s. The increase in coral Pb/Ca is accompanied by a decrease in coral 206Pb/207Pb and 208Pb/207Pb, indicating that the increase was caused by the infiltration of anthropogenic Pb to the coral growth site. Comparing our data to the surface coral Δ14C and Pb records from Bermuda reveals a time scale of tracer transport from the surface ocean to the coral growth site. Some characteristic features, e.g., the bomb-derived Δ14C increase, appear in the deep ocean approximately 25 yr later than the surface, but the overall increase of Δ14C and Pb in the deep ocean is smaller and slower than the surface, showing the importance of mixing during the transport of these tracers.

  7. Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead

    NASA Astrophysics Data System (ADS)

    Yang, Sha; Liu, Yun

    2015-07-01

    The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac’s formalism of full-electron wave function. Equilibrium 202Hg/198Hg, 205Tl/203Tl, 207Pb/206Pb and 208Pb/206Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of vs. for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb4+-bearing species are found can enrich heavier Pb isotopes than Pb2+-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of 208Pb/206Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb2+-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., ) and odd-mass MIFs (i.e., ) are almost the same but with opposite signs.

  8. Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead.

    PubMed

    Yang, Sha; Liu, Yun

    2015-07-30

    The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wave function. Equilibrium (202)Hg/(198)Hg, (205)Tl/(203)Tl, (207)Pb/(206)Pb and (208)Pb/(206)Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of [formula in text] for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb(4+)-bearing species are found can enrich heavier Pb isotopes than Pb(2+)-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of (208)Pb/(206)Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb(2+)-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., [formula in text]) and odd-mass MIFs (i.e., [formula in text) are almost the same but with opposite signs.

  9. Spatial Distribution of Lead Isotope Ratios and Inorganic Element Concentrations in Epiphytic Lichens from the Athabasca Oil Sands Region

    NASA Astrophysics Data System (ADS)

    Graney, J. R.; Landis, M. S.; Puckett, K.; Edgerton, E.; Krupa, S.; Percy, K.

    2013-12-01

    Coupled studies of inorganic element concentrations and lead (Pb) isotope ratios have been conducted on Hypogymnia physodes samples collected in the Athabasca Oil Sands Region (AOSR) in Alberta, Canada in 2002, 2008, and 2011. To investigate the spatial extent of air emissions, the lichens were collected from sites as far as 160 km from the mining and processing operations. 30 milligram sub-samples of the lichens were microwave digested, and the extracts were analyzed using DRC-ICPMS to determine elemental concentrations, and sector field ICPMS to measure Pb isotope ratios. Concentrations of elements in the lichens were found to reflect proximity to mining and oil processing sites as well as topography, ecosystem differences, and the metabolic biogeochemistry of the lichens. An exponential decrease in concentration of metals associated with fugitive dust (aluminum and others) versus distance from the mining sites, suggests elevated coarse particle emissions associated with mining operations. Near source concentrations of metals with an oil signature (vanadium and others) are less enhanced and more homogeneous than the metals in the fugitive dust, reflecting emission and deposition of smaller diameter particles at greater distances from oil processing sources. The mining and oil processing signatures are superimposed over elemental concentrations that reflect the nutrient needs of the lichens. These findings are being confirmed through ongoing studies using dichot samplers to collect coarse and fine particulate aerosol samples. The lichen samples collected beyond 50 km from the mining and processing sites cluster into a Pb isotope grouping with a 207Pb / 206Pb ratio of 0.8650 and a 208Pb / 206Pb ratio near 2.095. This grouping likely reflects the regional background Pb isotope ratio signature. 207Pb / 206Pb and 208Pb / 206Pb ratios decrease as one nears the mining and processing operations. This indicates that other Pb source(s), (e.g. Pb in the bitumen from the oil

  10. Structural variation in ethylenediamine and -diphosphine adducts of (2,6-Me2C6H3S)2Pb: a single crystal X-ray diffraction and 207Pb solid-state NMR spectroscopy study.

    PubMed

    Rossini, Aaron J; Macgregor, Alan W; Smith, Anita S; Schatte, Gabriele; Schurko, Robert W; Briand, Glen G

    2013-07-14

    Coordination complexes of (2,6-Me2C6H3S)2Pb (1) with flexible bidentate ligands have been prepared to explore new bonding environments for Pb(II) thiolates. The reaction of 1 with a series of ethylenediamine and ethylenediphosphine ligands resulted in isolation of the adducts [(2,6-Me2C6H3S)2Pb]2(tmeda) (9), [(2,6-Me2C6H3S)2Pb]3(dmpe) (10) and [(2,6-Me2C6H3S)2Pb]2(dppe) (11) [tmeda = N,N,N',N'-tetramethylethylenediamine; dmpe = bis(dimethylphosphino)ethane; dppe = bis(diphenylphosphino)ethane]. The X-ray crystal structure of 9 shows a dinuclear species in which tmeda is chelating a ψ-trigonal bipyramidal S2N2 Pb centre via axial and equatorial sites. The structure of 10 displays a trinuclear structural unit in which dmpe is chelating a ψ-trigonal bipyramidal S2P2 Pb centre via equatorial sites. Compounds 9 and 10 also contain a second unique metal centre with ψ-tetrahedral S3Pb bonding motifs. The structure of 11 shows the dppe ligand bridging two Pb ψ-tetrahedral S2P metal bonding environments. Static (207)Pb solid-state NMR (SSNMR) spectra of 9-11 and [Ph4As][(PhS)3Pb] (12) were acquired with cross polarization (CP)-CPMG and frequency swept pulse (WURST)-CPMG pulse sequences, and the efficiencies of these pulse sequences are compared. The (207)Pb SSNMR spectra reveal that the lead chemical shift anisotropies (CSA) vary greatly between the different Pb sites, and are generally large in magnitude. DFT calculations are utilized to relate the orientations of the (207)Pb nuclear magnetic shielding tensors to the molecular structures, and to aid in spectral assignment where multiple Pb centres are present. The combination of X-ray diffraction, (207)Pb SSNMR and DFT is shown to be invaluable for the structural characterization of these important structural motifs, and should find wide-ranging application to numerous lead coordination compounds.

  11. Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS and oxygen isotope documentation for a series of zircon standards

    USGS Publications Warehouse

    Black, L.P.; Kamo, S.L.; Allen, C.M.; Davis, D.W.; Aleinikoff, J.N.; Valley, J.W.; Mundil, R.; Campbell, I.H.; Korsch, R.J.; Williams, I.S.; Foudoulis, C.

    2004-01-01

    Precise isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) documentation is given for two new Palaeozoic zircon standards (TEMORA 2 and R33). These data, in combination with results for previously documented standards (AS3, SL13, QGNG and TEMORA 1), provide the basis for a detailed investigation of inconsistencies in 206Pb/238U ages measured by microprobe. Although these ages are normally consistent between any two standards, their relative age offsets are often different from those established by ID-TIMS. This is true for both sensitive high-resolution ion-microprobe (SHRIMP) and excimer laser ablation-inductively coupled plasma-mass spectrometry (ELA-ICP-MS) dating, although the age offsets are in the opposite sense for the two techniques. Various factors have been investigated for possible correlations with age bias, in an attempt to resolve why the accuracy of the method is worse than the indicated precision. Crystallographic orientation, position on the grain-mount and oxygen isotopic composition are unrelated to the bias. There are, however, striking correlations between the 206Pb/238U age offsets and P, Sm and, most particularly, Nd abundances in the zircons. Although these are not believed to be the primary cause of this apparent matrix effect, they indicate that ionisation of 206Pb/238U is influenced, at least in part, by a combination of trace elements. Nd is sufficiently representative of the controlling trace elements that it provides a quantitative means of correcting for the microprobe age bias. This approach has the potential to reduce age biases associated with different techniques, different instrumentation and different standards within and between laboratories. Crown Copyright ?? 2004 Published by Elsevier B.V. All rights reserved.

  12. Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin

    NASA Astrophysics Data System (ADS)

    Richter, T. O.; de Stigter, H. C.; Boer, W.; Jesus, C. C.; van Weering, T. C. E.

    2009-02-01

    Submarine canyons represent natural conduits for preferential transport of particulate material, including anthropogenic contaminants, from coastal zones directly to the deep sea. To assess related dispersal of natural and anthropogenic lead (Pb), we analyzed Pb concentrations and stable isotope ratios in surface sediments and sediment trap particulate material from the Portuguese margin Nazaré and Setúbal/Lisbon canyons. Geochemical data are integrated with previously obtained data on near-bottom hydrodynamics and processes and pathways of sediment transport. The two canyon systems are located in close geographic proximity to each other, but represent contrasting settings in terms of sediment input and down-canyon sediment transport processes. Concentration-isotope diagrams and three-isotope plots ( 206Pb/ 207Pb vs. 208Pb/ 206Pb) suggest binary mixing between natural and anthropogenic end members. The inferred isotopic signature of pollutant Pb ( 206Pb/ 207Pb=1.143 [1.134-1.149, 95% confidence interval]) is most consistent with industrial Pb; ongoing influence from gasoline Pb additives is at most of minor importance. Two proposed natural end members most likely bracket the isotopic signature of natural Pb. Accordingly, binary mixing calculations indicate that on average 20-45% vs. 35-55% of total Pb is derived from anthropogenic sources in the Nazaré and Setúbal-Lisbon canyon systems, respectively. Enhanced anthropogenic influence in the latter area is consistent with its proximity to heavily populated and industrialized areas and with sediment input from the Tagus and Sado rivers, potential major carriers of pollutant particles. In both canyon systems, the anthropogenic component generally decreases with increasing water depth. Isotopic signatures of sediment trap particulate material are generally consistent with surface sediment data at similar water depth, but show large variability in the upper Nazaré canyon and major deviations from surface sediments

  13. Trace metal inventories and lead isotopic composition chronicle a forest fire's remobilization of industrial contaminants deposited in the angeles national forest.

    PubMed

    Odigie, Kingsley O; Flegal, A Russell

    2014-01-01

    The amounts of labile trace metals: [Co] (3 to 11 µg g-1), [Cu] (15 to 69 µg g-1), [Ni] (6 to 15 µg g-1), [Pb] (7 to 42 µg g-1), and [Zn] (65 to 500 µg g-1) in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (208Pb/207Pb: 206Pb/207Pb) that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change.

  14. A study of radionuclides, metals and stable lead isotope ratios in sediments and soils in the vicinity of natural U-mineralisation areas in the Northern Territory.

    PubMed

    Frostick, A; Bollhöfer, A; Parry, D

    2011-10-01

    Australian guidelines recommend that tailings materials from uranium (U) mining and milling be contained without any detrimental impact on the environment for at least 1000 years. Natural analogue sites are being investigated to determine if they can provide data on the rates of natural erosion processes which occur over these timescales, for input into predictive geomorphic computer models. This paper presents radionuclide, metal and stable lead (Pb) isotope data from sediment cores and surface soils in the vicinity of two mineralised areas in the Alligator Rivers Region. Surface scrapes from the natural Anomaly #2, south of the Ranger mineral lease, exhibit radiogenic (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios, and elevated U and metal concentrations typical for a near surface U anomaly. In contrast, samples taken from the Koongarra mineral lease (KML) show radionuclide activity and metal concentrations similar to natural areas elsewhere in the Alligator Rivers Region and Pb isotope ratios are closer to present day average crustal ratios (PDAC), as the orebodies at KML are covered by surficial sand. A sediment core collected from Anbangbang Billabong, downstream of KML, exhibits small variations in Pb isotope ratios that indicate that approximately 1% of the upper sediments in the sediment core may be derived from material originating from the U anomaly at Koongarra.

  15. Reconstructing lead isotope exposure histories preserved in the growth layers of walrus teeth using the SHRIMP II ion microprobe

    SciTech Connect

    Stern, R.A.; Outridge, P.M.; Davis, W.J.; Stewart, R.E.A.

    1999-05-15

    Development of a microprobe technique to determine Pb isotope ratios within the growth layers of mammal teeth could have widespread applications in Pb toxicology, Pb pollution tracing, and human and animal ecology. Here, the SHRIMP II ion microprobe is shown to possess sufficient sensitivity, accuracy, and precision to satisfactorily determine Pb isotope ratios in the canine tooth cementum of a walrus (Odobenus rosmarus rosmarus), with a sampling resolution of 130 {micro}m. The tooth layers were estimated to contain only 1--3 {micro}g/gf Pb. By combining multiple replicates within each annual layer, the {+-}1 SE uncertainty was typically {+-}1% for {sup 206}Pb/{sup 207}Pb and {+-}0.5% for {sup 208}Pb/{sup 207}Pb. Significant isotopic differences were found between layers deposited at age 10 and ages 2, 27, and 30. This result, together with corroborative data on excised cementum fragments analyzed by thermal ionization mass spectrometry, indicates that the animal migrated into different geological terrains several times during its life. There was no evidence of exchange between the Pb deposited in early growth layers and more recent ambient Pb.

  16. Heavy metals pollution and pb isotopic signatures in surface sediments collected from Bohai Bay, North China.

    PubMed

    Gao, Bo; Lu, Jin; Hao, Hong; Yin, Shuhua; Yu, Xiao; Wang, Qiwen; Sun, Ke

    2014-01-01

    To investigate the characteristics and potential sources of heavy metals pollution, surface sediments collected from Bohai Bay, North China, were analyzed for the selected metals (Cd, Cr, Cu, Ni, Pb, and Zn). The Geoaccumulation Index was used to assess the level of heavy metal pollution. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were 0.15, 79.73, 28.70, 36.56, 25.63, and 72.83 mg/kg, respectively. The mean concentrations of the studied metals were slightly higher than the background values. However, the heavy metals concentrations in surface sediments in Bohai Bay were below the other important bays or estuaries in China. The assessment by Geoaccumulation Index indicated that Cr, Zn, and Cd were classified as "the unpolluted" level, while Ni, Cu, and Pb were ranked as "unpolluted to moderately polluted" level. The order of pollution level of heavy metals was: Pb > Ni > Cu > Cr > Zn > Cd. The Pb isotopic ratios in surface sediments varied from 1.159 to 1.185 for (206)Pb/(207)Pb and from 2.456 to 2.482 for (208)Pb/(207)Pb. Compared with Pb isotopic radios in other sources, Pb contaminations in the surface sediments of Bohai Bay may be controlled by the mix process of coal combustion, aerosol particles deposition, and natural sources.

  17. Spatial distribution, health risk assessment, and isotopic composition of lead contamination of street dusts in different functional areas of Beijing, China.

    PubMed

    Han, Lanfang; Gao, Bo; Wei, Xin; Xu, Dongyu; Gao, Li

    2016-02-01

    Street dusts from heavy density traffic area (HDTA), tourism area (TA), residential area (RA), and educational area (EA) in Beijing were collected to explore the distribution, health risk assessment, and source of lead (Pb). The average concentration of Pb in TA was the highest among the four areas. Compared with other cities, Pb concentrations in Beijing were generally at moderate or low levels. The average value (14.05) of ecological risk index (RI) indicated that Pb was at "low pollution risk" status. According to the calculation on hazard index (HI), the ingestion of dust particles of children and adults was the major route of exposure to street dusts in four studied areas, followed by dermal contact. The lower values of HI than 1 further suggested that non-carcinogenic risks of Pb in the street dusts were in the low range. Comparing (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of street dusts with other environmental samples, it was found that atmospheric deposition of coal combustion dust might be the main pathway for anthropogenic Pb input to the street dusts in four functional areas.

  18. Trace Metal Inventories and Lead Isotopic Composition Chronicle a Forest Fire’s Remobilization of Industrial Contaminants Deposited in the Angeles National Forest

    PubMed Central

    Odigie, Kingsley O.; Flegal, A. Russell

    2014-01-01

    The amounts of labile trace metals: [Co] (3 to 11 µg g−1), [Cu] (15 to 69 µg g−1), [Ni] (6 to 15 µg g−1), [Pb] (7 to 42 µg g−1), and [Zn] (65 to 500 µg g−1) in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (208Pb/207Pb: 206Pb/207Pb) that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change. PMID:25259524

  19. Characteristics of Heavy Metals and Pb Isotopic Composition in Sediments Collected from the Tributaries in Three Gorges Reservoir, China

    PubMed Central

    Gao, Bo; Zhou, Huaidong; Huang, Yong; Wang, Yuchun; Gao, Jijun; Liu, Xiaobo

    2014-01-01

    The concentrations, distribution, accumulation, and potential ecological risk of heavy metals (Cr, Cu, Zn, Ni, As, Pb, Cd, and Hg) in sediments from the Three Gorges Reservoir (TGR) tributaries were determined and studied. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of heavy metals in sediment of TGR tributaries were higher than the local background values of soils and sediments in China. The assessment by Geoaccumulation Index indicated that Cu, Ni, and Hg were at the “slightly polluted” level and Cd was ranked as the “moderately polluted” level in tributary sediments of TGR. The assessment by Potential Ecological Risk Index showed that Hg and Cd were the predominant elements in tributary sediments in TGR. The Pb isotopic ratios in sediments varied from 1.171 to 1.202 for 206Pb/207Pb and from 2.459 to 2.482 for 208Pb/207Pb in TGR. All Pb isotopic ratios in sediments were similar to those from coal combustion, lead ores (the mining activities and smelting process), and cement material, indicating that these anthropogenic inputs may be the main sources for Pb pollution in sediments of TGR tributaries. PMID:24624045

  20. Primitive and contaminated basalts from the Southern Rocky Mountains, U.S.A

    USGS Publications Warehouse

    Doe, B.R.; Lipman, P.W.; Hedge, C.E.; Kurasawa, H.

    1969-01-01

    to the primitive basalts in lead isotope ratios. The primitive basalts have: 206Pb/204Pb ??? 18.09-18.34, 207Pb/204Pb ??? 15.5, 208Pb/204Pb ??? 37.6-37.9, 87Sr/86Sr ??? 0.704-0.705. In the primitive basalts from the Southern Rocky Mountains the values of 206Pb/204Pb are similar to values reported by others for Hawaiian and eastern Honshu basalts and abyssal basalts, whereas 208Pb/204Pb tends to be equal to or a little less radiogenic than those from the oceanic localities. 87Sr/86Sr appears to be equal to or a little greater than those of the oceanic localities. These 206Pb/204Pb and 208Pb/204Pb ratios are distinctly less radiogenic and 87Sr/86Sr values are about equal to those reported by others for volcanic islands on oceanic ridges and rises. ?? 1969 Springer-Verlag.

  1. The source of natural and anthropogenic heavy metals in the sediments of the Minjiang River Estuary (SE China): implications for historical pollution.

    PubMed

    Xu, Yonghang; Sun, Qinqin; Yi, Liang; Yin, Xijie; Wang, Aijun; Li, Yunhai; Chen, Jian

    2014-09-15

    Two sedimentary cores in the Minjiang River estuary (SE China) are documented for grain size, clay minerals, heavy metals, magnetic parameters and Pb isotopes to investigate the source and historical variation of heavy metals. The MJK9 core was collected outside of the Minjiang River estuary, and the core is composed of mixed sediments, of which ~70% from the Yangtze River and 30% from the Minjiang River. It is thus difficult to be used for tracing the human activity along the Minjiang River. In contrast, the sediments of MJK16 core which was collected in a nearshore area are primarily from the Minjiang River. The enrichment factors of the sediments were <1.5, indicating minor pollution. The results indicate that the sediments of the MJK16 core have Cu and Pb concentrations increasing since 1980, associated with the increase of magnetic mineral concentration and (206)Pb/(207)Pb and (206)Pb/(208)Pb of the sediments. We compared the Pb isotopic compositions between our results and those for the deposit mining in the Minjiang River basin, and aerosols and coal dust in south China, and considered that Pb in the sediments of the MJK16 core was derived primarily from weathered rocks as well as industrial emission (e.g. coal combustion). The sediments have anthropogenic Pb concentrations ranging from 6% in 1950 to 23.7% in 2010, consistent with the impact of rapid urban and industrial development in China.

  2. Chronological trends in trace metals recorded by a tree bark pocket in Yakushima Island, Japan.

    PubMed

    Bellis, David J; Satake, Kenichi; Kagawa, Akira

    2005-04-01

    Bark included within the trunk of a 200-year-old Japanese cedar tree harvested in Yakushima Island, Japan, a World Natural Heritage Site located 150 km south of mainland Japan and 800 km east of Shanghai, China, was analysed for trace metals by ICP-MS providing a chronology of atmospheric pollution. The concentration of V, As and Pb in decadal sections of the bark pocket increased 30 to 50 fold from 1900-09 to 1960-69, indicating increased atmospheric deposition of these metals. The trend coincided with the establishment and expansion of heavy industries in Kyushu, Japan, resulting in locally high levels of air pollution. V, As and Pb subsequently declined, reflecting lower industrial emissions following air pollution control legislation from the late 1960's and decline in heavy industries. Ni, Cu and Zn showed a relatively small, 7 to 10 fold increase over time. Lead isotope ratios in the bark pockets shifted from about 0.84 to 0.86 for 207Pb/206Pb and from 2.04 to 2.10 for 208Pb/206Pb, showing that the origin of atmospheric lead changed over time from coal to more diverse sources.

  3. Lead isotopes in the western North Atlantic: transient tracers of pollutant lead inputs.

    PubMed

    Véron, A J; Church, T M; Flegal, A R

    1998-08-01

    In the early 1980s, Patterson and colleagues demonstrated that most lead in oceanic surface waters had an anthropogenic origin. Their discovery occurred during the phasing out of leaded gasoline in North America initiated in the previous decade. The corresponding decrease in the anthropogenic lead emissions, verified by Pb/210Pb ratios, accounted for the systematic decline in lead concentrations in surface waters of the western Sargasso Sea. Subsequent changes in anthropogenic lead inputs to the western Sargasso Sea surface waters have been documented by measurements of lead concentrations, isotopic compositions (206Pb/207Pb, 208Pb/206Pb), and Pb/210Pb ratios in precipitation and seawater for the period of 1981 to 1994. These data indicate the easterly trade winds are now the primary source of atmospheric lead in Bermuda, and they confirm that the decline of lead concentrations in the North Atlantic is associated with the phasing out of leaded gasoline in North America and western Europe over the past decade. Moreover, temporal variations in the relative contribution of industrial lead inputs from the two sides of the North Atlantic over that period can be quantified based on differences in their isotopic composition. The transient character of those isotopic signatures also allows calculations of pollutant lead penetration rates into the mixed layer and upper thermocline of the western Sargasso Sea.

  4. Assessment of lead bioaccessibility in soils around lead battery plants in East China.

    PubMed

    Jin, Zan-fang; Zhang, Zhuo-jun; Zhang, Hui; Liu, Cong-qiang; Li, Fei-li

    2015-01-01

    Soil ingestion is an important human exposure pathway for lead (Pb). A modified physiologically based extraction test was applied to 70 soil samples from five battery plants in East China. The mean values for soil pH, soil organic matter, Fe and Mn concentrations ranged from 5.9% to 8.1, 0.37% to 2.2%, 2.78% to 3.75%, and 507-577 mg kg(-1), respectively, while Pb concentrations ranged widely in 14.3-2000 mg kg(-1). The isotopic ratios of 14 soils from one of the five battery plants formed a straight line in the plot of (208)Pb/(206)Pb vs. (207)Pb/(206)Pb, indicating Pb emissions from the lead battery plant as the dominant anthropogenic source within 200 m. Lead bioaccessibility in the soils ranged from 4.1% to 66.9% in the gastric phase and from 0.28% to 9.29% in the gastrointestinal phase. Multiple step regressions identified modes as BAgastric=-106.8+0.627[Pb]+19.1[Fe]+11.3[SOM], and BAgastrointestinal=-2.852+0.078[Pb].

  5. Lead in blood and eggs of the sea turtle, Lepidochelys olivacea, from the Eastern Pacific: concentration, isotopic composition and maternal transfer.

    PubMed

    Páez-Osuna, F; Calderón-Campuzano, M F; Soto-Jiménez, M F; Ruelas-Inzunza, J R

    2010-03-01

    Concentrations of lead were assessed in the sea turtle, Lepidochelys olivacea, from a nesting colony of the Eastern Pacific. Twenty-five female turtles were sampled and a total of 250 eggs were collected during the "arribada" event of the 2005-2006 season. Considering the nesting season, the maternal transfer of lead (Pb) via egg-laying, in terms of metal burden in whole body, was 0.5%. Pb concentrations (in dry weight) in blood (0.95+/-0.18microgg(-1)) and egg samples (yolk, 0.80+/-0.10microg g(-1); albumen, 1.08+/-0.20microg g(-1); eggshell, 1.05+/-0.20microg g(-1)) were comparable or even lower than those found in other sea turtles. The isotope ratios ((206)Pb/(207)Pb and (206)Pb/(208)Pb) in blood (1.183+/-0.0006 and 2.452+/-0.0006, respectively) were comparable to that of natural Pb-bearing bedrock in Mexico (1.188+/-0.005 and 2.455+/-0.008, respectively). According to international norms of Pb, the health of this population and its habitats is acceptable for Pb and corresponds to basic levels of a nearly pristine environment.

  6. Impact on the environment from steel bridge paint deterioration using lead isotopic tracing, paint compositions and soil deconstruction.

    PubMed

    Gulson, Brian; Chiaradia, Massimo; Davis, Jeffrey; O'Connor, Gary

    2016-04-15

    Deterioration and repair of lead paint on steel structures can result in contamination of the ambient environment but other sources of lead such as from past use of leaded paint and gasoline and industrial activities can also contribute to the contamination. Using a combination of high precision lead isotopic tracing, detailed paint examination, including with scanning electron microscopy, and soil deconstruction we have compared paint on a steel bridge and bulk soil and lead-rich particles separated from soil. The majority of Pb found in the paint derives from Australian sources but some also has a probable US origin. The isotopic data for the bulk soils and selected particles lie on a mixing line with end members the geologically ancient Broken Hill lead and possible European lead which is suggested to be derived from old lead paint and industrial activities. Data for gasoline-derived particulates lie on this array and probably contribute to soil Pb. Although paint from the bridge can be a source of lead in the soils, isotopic tracing, paint morphology and mineralogical identification indicate that other sources, including from paint, gasoline and industrial activities, are contributing factors to the lead burden. Even though physical characteristics and elemental composition are the same in some particles, the isotopic signatures demonstrate that the sources are different. Plots using (206)Pb/(208)Pb vs (206)Pb/(207)Pb ratios, the common representation these days, do not allow for source discrimination in this investigation.

  7. Identifying the sources and timing of ancient and medieval atmospheric lead pollution in England using a peat profile from Lindow bog, Manchester.

    PubMed

    Le Roux, Gaël; Weiss, Dominik; Grattan, John; Givelet, Nicolas; Krachler, Michael; Cheburkin, Andriy; Rausch, Nicole; Kober, Bernd; Shotyk, William

    2004-05-01

    A peat core from Lindow bog near Manchester, England, was precisely cut into 2 cm slices to provide a high-resolution reconstruction of atmospheric Pb deposition. Radiocarbon and (210)Pb age dates show that the peat core represents the period ca. 2000 BC to AD 1800. Eleven radiocarbon age dates of bulk peat samples reveal a linear age-depth relationship with an average temporal resolution of 18.5 years per cm, or 37 years per sample. Using the Pb/Ti ratio to calculate the rates of anthropogenic, atmospheric Pb deposition, the profile reveals Pb contamination first appearing in peat samples dating from ca. 900 BC which clearly pre-date Roman mining activities. Using TIMS, MC-ICP-MS, and SF-ICP-MS to measure the isotopic composition of Pb, the (208)Pb/(206)Pb and (206)Pb/(207)Pb data indicate that English ores were the predominant sources during the pre-Roman, Roman, and Medieval Periods. The study shows that detailed studies of peat profiles from ombrotrophic bogs, using appropriate preparatory and analytical methods, can provide new insight into the timing, intensity, and predominant sources of atmospheric Pb contamination, even in samples dating from ancient times.

  8. Rapid release and changing sources of Pb in a mountainous watershed during extreme rainfall events.

    PubMed

    Jo, Kyeong-Won; Park, Ji-Hyung

    2010-12-15

    Although atmospheric Pb is known to accumulate in forest soils over time, little is known about the hydrologic Pb export from mountain forest soils. Short-term changes in Pb release and its sources during monsoon rainfall events were investigated in a mountainous watershed in the northern extreme of South Korea by combining intensive storm sampling with measurements of Pb concentrations and isotope ratios in soils and size-fractionated sediments. Biweekly monitoring of forest and agricultural streams showed relatively low dissolved Pb concentrations compared to those found in precipitation. Particulate Pb concentrations in both streams were higher than the dissolved concentrations and increased rapidly during rainfall events. Particulate Pb concentrations were substantially higher in the agricultural stream; the highest concentrations were associated with silt-size sediment followed by sand. A comparison of (206)Pb/(207)Pb and (208)Pb/(206)Pb among sediment fractions and source soils indicated that major sources for silt- and sand-associated Pb in the agricultural stream change between streambank and cropland soils, whereas Pb in the forest stream is primarily derived from forest floors. The results suggest that Pb isotopes can be efficiently applied to tracing short-term changes in sediment and Pb sources and that extreme rainfall events can significantly increase Pb mobilization from erosion-prone mountain soils.

  9. Tracing source and migration of Pb during waste incineration using stable Pb isotopes.

    PubMed

    Li, Yang; Zhang, Hua; Shao, Li-Ming; He, Pin-Jing

    2017-04-05

    Emission of Pb is a significant environmental concern during solid waste incineration. To target Pb emission control strategies effectively, the major sources of Pb in the waste incineration byproducts must be traced and quantified. However, identifying the migration of Pb in each waste component is difficult because of the heterogeneity of the waste. This study used a laboratory-scale incinerator to simulate the incineration of municipal solid waste (MSW). The Pb isotope ratios of the major waste components ((207)Pb/(206)Pb=0.8550-0.8627 and (208)Pb/(206)Pb=2.0957-2.1131) and their incineration byproducts were measured to trace sources and quantify the Pb contribution of each component to incineration byproducts. As the proportions of food waste (FW), newspaper (NP), and polyethylene bag (PE) in the artificial MSW changed, the contribution ratios of FW and PE to Pb in fly ash changed accordingly, ranging from 31.2% to 50.6% and from 35.0% to 41.8%, respectively. The replacement of PE by PVC significantly increased the partitioning and migration ratio of Pb. The use of Pb isotope ratios as a quantitative tool for tracing Pb from raw waste to incineration byproducts is a feasible means for improving Pb pollution control.

  10. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

    SciTech Connect

    Hegner, E.; Tatsumoto, M.

    1987-10-10

    Pb, Sr, Nd isotopes of seven basalt glasses collected by the submersible Alvin from the southern Juan de Fuca Ridge (SJFR) are almost identical (/sup 206/Pb//sup 204/Pbapprox.18.45, /sup 207/Pb//sup 204/Pbapprox.15.47, /sup 208/Pb//sup 204/Pbapprox.37.81, /sup 87/Sr//sup 86/Srapprox.0.70249, /sup 143/Nd//sup 144/Ndapprox.0.51315). Whereas all basalts appear cogenetic, four of the samples have uniform abundances of U, Th, Rb, Nd, Sm, Pb, and Sr, indicating that they are also comagmatic. Two basalt glasses dredged previously at the SJFR have similar isotopic compositions but higher concentrations of U, Th, and Pb. The /sup 206/Pb//sup 204/Pb ratios are intermediate between generally less radiogenic ridge basalts from south of the Juan de Fuca Ridge (JFR) and often more radiogenic basalts from the northern JFR and NE Pacific seamounts. Sr and Nd isotopic compositions closely resemble data of other ridge basalts from the northernmost East Pacific Rise and are intermediate between isotopically more diverse seamount basalts produced nearby.

  11. High-precision analysis on annual variations of heavy metals, lead isotopes and rare earth elements in mangrove tree rings by inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Yu, Ke-Fu; Kamber, Balz S.; Lawrence, Michael G.; Greig, Alan; Zhao, Jian-Xin

    2007-02-01

    Annual variations from 1982 to 1999 of a wide range of trace elements and reconnaissance Pb isotopes ( 207Pb/ 206Pb and 208Pb/ 206Pb) were analyzed by solution ICP-MS on digested ash from mangrove Rhizophora apiculata, obtained from Leizhou Peninsula, along northern coast of South China Sea. The concentrations of the majority of elements show a weak declining trend with growth from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with inferred water-use efficiency, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement or growth activities and appear to be related to environmental pollution events. Pb isotope ratios for most samples plot along the 'Chinese Pb line' and clearly document the importance of gasoline Pb as a source of contaminant. Shale-normalised REE + Y patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Ce anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants. This pilot study of trace element, REE + Y and Pb isotope distribution in mangrove tree rings indicates the potential use of mangroves as monitors of historical environmental change.

  12. Ancient bronze coins from Mediterranean basin: LAMQS potentiality for lead isotopes comparative analysis with former mineral

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Italiano, A.; Torrisi, A.

    2016-11-01

    Bronze coins coming from the area of the Mediterranean basin, dated back the II-X Cent. A.D., were analyzed using different physical analytical techniques. Characteristic X-ray fluorescence was used with electrons and photons, in order to investigate the elemental composition of both the surface layers and bulk. Moreover, the quadrupole mass spectrometry coupled to laser ablation (LAMQS technique) in high vacuum was used to analyse typical material compounds from surface contamination. Mass spectrometry, at high resolution and sensitivity, extended up to 300 amu, allowed measuring the 208Pb/206Pb and 207Pb/206Pb isotopic ratios into the coins. Quantitative relative analyses of these isotopic ratios identify the coin composition such as a ;fingerprint; depending on the mineral used to extract the lead. Isotopic ratios in coins can be compared to those of the possible minerals used to produce the bronze alloy. A comparison between the measured isotope ratios in the analyzed coins and the literature database, related to the mineral containing Pb as a function of its geological and geophysical extraction mine, is presented. The analysis, restricted to old coins and the mines of the Mediterranean basin, indicates a possible correlation between the coin compositions and the possible geological sites of the extracted mineral.

  13. Lead isotopes in the western North Atlantic: Transient tracers of pollutant lead inputs

    SciTech Connect

    Veron, A.J. |; Church, T.M.; Flegal, A.R.

    1998-08-01

    In the early 1980s, Patterson and colleagues demonstrated that most lead in oceanic surface waters had an anthropogenic origin. Their discovery occurred during the phasing out of leaded gasoline in North America initiated in the previous decade. The corresponding decrease in anthropogenic lead emissions, verified by Pb/{sup 210}Pb ratios, accounted for the systematic decline in lead concentrations in surface waters of the western Sargasso Sea. Subsequent changes in anthropogenic lead inputs to the western Sargasso Sea surface waters have been documented by measurements of lead concentrations, isotopic compositions ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 206}Pb), and Pb/{sup 210}Pb ratios in precipitation and seawater for the period of 1981 to 1994. These data indicate the easterly trade winds are now the primary source of atmospheric lead in Bermuda, and they confirm that the decline of lead concentrations in the North Atlantic is associated with the phasing out of leaded gasoline in North America and western Europe over the past decade. Moreover, temporal variations in the relative contribution of industrial lead inputs from the two sides of the North Atlantic over that period can be quantified based on differences in their isotopic composition. The transient character of those isotopic signatures also allows calculations of pollutant lead penetration rates into the mixed layer and upper thermocline of the western Sargasso Sea.

  14. Southwestern limits of Indian Ocean Ridge mantle and the origin of low Pb-206/Pb-204 mid-ocean ridge basalt - Isotope systematics of the central Southwest Indian Ridge (17 deg - 50 deg E)

    NASA Astrophysics Data System (ADS)

    Mahoney, J.; Le Roex, A. P.; Peng, Z.; Fisher, R. L.; Natland, J. H.

    1992-12-01

    The isotopic characteristics of the Indian Ocean Ridge midocean ridge basalts (MORBs) and of the Atlantic and the Pacific MORBs (north of 25 deg S) were determined in order to estimate the southwestern limits of the Indian Ocean Ridge mantle and the origin of low Pb-206/Pb-204 MORB. In view of the possible importance of a Marion-type mantle along portions of the ridge, lavas from several Marion Island, Prince Edward Island, and Funk Seamount were also analyzed isotopically. The isotopic results include analyses of fields for the Indian Ocean triple junction area, the entire Central Indian and southern Carlsberg ridges, for several oceanic islands, and Pacific and/or North Atlantic MORBs.

  15. Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

    USGS Publications Warehouse

    Stern, C.R.; Frey, F.A.; Futa, K.; Zartman, R.E.; Peng, Z.; Kurtis, Kyser T.

    1990-01-01

    The Pliocene and Quaternary Patagonian alkali basalts of southernmost South America can be divided into two groups. The "cratonic" basalts erupted in areas of Cenozoic plateau volcanism and continental sedimentation and show considerable variation in 87Sr/86Sr (0.70316 to 0.70512), 143Nd/144Nd (e{open}Nd) and 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios (18.26 to 19.38, 15.53 to 15.68, and 38.30 to 39.23, respectively). These isotopic values are within the range of oceanic island basalts, as are the Ba/La, Ba/Nb, La/Nb, K/Rb, and Cs/Rb ratios of the "cratonic" basalts. In contrast, the "transitional" basalts, erupted along the western edge of the outcrop belt of the Pliocene and Quaternary plateau lavas in areas that were the locus of earlier Cenozoic Andean orogenic arc colcanism, have a much more restricted range of isotopic composition which can be approximated by 87Sr/86Sr=0.7039??0.0004, e{open}Nd, 206Pb/204Pb=18.60??0.08, 207Pb/204Pb=15.60??0.01, and 208Pb/204Pb=38.50??0.10. These isotopic values are similar to those of Andean orogenic are basalts and, compared to the "cratonic" basalts, are displaced to higher 87Sr/86Sr at a given 143Nd/144Nd and to higher 207Pb/204Pb at a given 208Pb/204Pb. The "transitional" basalts also have Ba/La, Ba/Nb, La/Nb, and Cs/Rb ratios higher than the "cratonic" and oceanic island basalts, although not as high as Andean orogenic are basalts. In contrast to the radiogenic isotopes, ??18O values for both groups of the Patagonian alkali basalts are indistinguishable and are more restricted than the range reported for Andean orogenic are basalts. Whole rock ??18O values calculated from mineral separates for both groups range from 5.3 to 6.5, while measured whole rock ??18O values range from 5.1 to 7.8. The trace element and isotopic data suggest that decreasing degrees of partial melting in association with lessened significance of subducted slabderived components are fundamental factors in the west to east transition from arc

  16. Petrogenesis of pegmatites and granites in southwestern Maine

    SciTech Connect

    Tomascak, P.B.; Walker, R.J.; Krogstad, E.J. . Dept. of Geology)

    1993-03-01

    Granitic pegmatites occurring near the town of Topsham in southwestern Maine are mineralogically diverse, featuring abundant dikes and contain rare earth element minerals as well as one pegmatite that contains Li minerals. The pegmatite series crops out near the Brunswick granite, a texturally diverse granitic pluton, and lies 13 km southeast of the Mississippian age Sebago batholith. Areas intruded by pegmatites that possess such different mineral assemblages are globally rare. The origins of these mixed'' pegmatite series have not been comprehensively investigated. There is no known pattern of regional zonation (mineral/chemical) among Topsham series pegmatites, hence simple fractionation processes are probably not responsible for the compositional variations. The authors are attempting to clarify pegmatite petrogenesis using common Pb isotopic ratios of feldspars and Sm-Nd isotopic data from whole rocks and minerals. Pb isotopic ratios from leached feldspars reflect the Pb ratios of the source from which they were derived. The range of Pb isotopic compositions of alkali feldspars from 7 granitic pegmatites is as follows: [sup 206]Pb/[sup 204]Pb = 18.5-19.1; [sup 207]Pb/[sup 204]Pb = 15.53-15.69; [sup 208]Pb/[sup 204]Pb = 38.3-38.6. The Brunswick granite has K-feldspars with [sup 206]Pb/[sup 204]Pb = 18.40-18.47, [sup 207]/[sup 204]Pb = 15.64-15.66 and [sup 208]Pb/[sup 204]Pb = 38.29-38.39. The Pb isotopic compositions of both pegmatites and granites are significantly more radiogenic than existing data for the Sebago granite and argue against the consanguinity of Topsham pegmatites and the Sebago batholith. These data instead support a genetic link between the pegmatites and the Brunswick granite, which ranges from a fine-grained two-mica granite to a garnet-bearing pegmatitic leucogranite.

  17. Nuclear level densities in {sup 208}Bi and {sup 209}Po from the neutron spectra in the (p, n) reactions on {sup 208}Pb and {sup 209}Bi nuclei

    SciTech Connect

    Zhuravlev, B. V. Lychagin, A. A. Titarenko, N. N.; Demenkov, V. G.; Trykova, V. I.

    2010-07-15

    The spectra of neutrons from the (p, n) reactions on the {sup 208}Pb and {sup 209}Bi nuclei were measured in the proton-energy range 8-11 MeV. These measurements were performed by using a time-of-flight spectrometer of fast neutrons on the basis of the pulsed tandem accelerator EGP-15 of the Institute of Physics and Power Engineering (Obninsk, Russian Federation). A high resolution and stability of the time-of-flight spectrometermade it possible to identify reliably low-lying discrete levels alongwith the continuum section of the neutron spectra. The measured data were analyzed on the basis of the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations were performed by using the precise formalism of Hauser-Feshbach statistical theory together with the generalized model of a superfluid nucleus and the back-shifted Fermi gas model for the nuclear-level density. The nuclear-level densities in {sup 208}Bi and {sup 209}Po were determined along with their energy dependencies and model parameters. Our results are discussed together with available experimental data and recommendations of model systematics.

  18. Comparison of reactions for the production of {sup 258,257}Db: {sup 208}Pb({sup 51}V,xn) and {sup 209}Bi({sup 50}Ti,xn)

    SciTech Connect

    Gates, J. M.; Nelson, S. L.; Dragojevic, I.; Duellmann, Ch. E.; Ellison, P. A.; Folden III, C. M.; Garcia, M. A.; Hoffman, D. C.; Nitsche, H.; Gregorich, K. E.; Stavsetra, L.; Sudowe, R.

    2008-09-15

    Excitation functions for the 1n and 2n exit channels of the {sup 208}Pb({sup 51}V,xn){sup 259-x}Db reaction were measured. A maximum cross section of the 1n exit channel of 2070{sub -760}{sup +1100} pb was measured at an excitation energy of 16.0 {+-} 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660{sub -370}{sup +450} pb was measured at 22.0 {+-} 1.8 MeV excitation energy. The 1n excitation function for the {sup 209}Bi({sup 50}Ti,n){sup 258}Db reaction was remeasured, resulting in a cross section of 5480{sub -1370}{sup +1730} pb at an excitation energy of 16.0 {+-} 1.6 MeV, in agreement with previous values [F. P. Hessberger et al., Eur. Phys. J. A 12, 57 (2001)]. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.

  19. Heavy-Ion Transfer Reactions with Deformed Nuclei

    NASA Astrophysics Data System (ADS)

    Helmer, Karl Gerard

    1992-01-01

    One-neutron transfer reactions involving actinide nuclei are used to investigate the effects of rotational motion on transfer populations. Deexcitation gamma rays were measured using a particle -particle-gamma triple coincidence method. Rotational states up to 28^{+ }(30^{+}) were seen in ^{234}U originating from the reaction ^{235}U( ^{206}Pb, ^ {207}Pb)^{234} U at a laboratory bombarding energy of 1394 MeV. Angular distributions for both inelastic excitation and transfer are presented and the one-neutron transfer reaction cross section as well as the grazing angle have been extracted. This study demonstrates the feasibility of using heavy-ion induced transfer reactions for spectroscopic studies. The second section of this thesis explores the question of diabolical pair transfer in nuclear physics using the reactions ^{206}Pb( ^{156}Gd, ^ {154}Gd)^{208} Pb (diabolical case) and ^{206 }Pb(^{156}Gd, ^{158}Gd)^ {204}Pb (nondiabolic case) at a laboratory bombarding energy of 888 MeV. Early calculations by Nikam, Ring and Canto predicted oscillatory behavior of pair transfer matrix elements as the cranking frequency was varied, within the cranking Hartree-Fock-Bogoliubov (CHFB) model, and explained this behavior as a manifestation of Berry's phase. Significant suppression of the high spin population in the diabolical nucleus was predicted. The diabolical point is supplied by the crossing of the ground-state band with the two-quasiparticle band. The strength of this band interaction is predicted to be oscillatory with chemical potential in the CHFB model. The study of pair transfer populations can therefore shed light not only on the possible existence of Berry's phase in nuclear systems, but also on whether the band interaction goes strictly to zero as predicted by the CHFB model. The results of this experiment agree with the latest calculations that the expected effects are more subtle than the earliest calculations predicted.

  20. Lead-isotopic data from sulfide minerals from the Cascade Range, Oregon and Washington

    USGS Publications Warehouse

    Church, S.E.; LeHuray, A.P.; Grant, A.R.; Delevaux, M.H.; Gray, J.E.

    1986-01-01

    Lead-isotopic studies of mineral deposits associated with Tertiary plutons found in the Cascade Range of Oregon and Washington demonstrate a rather uniform isotopic composition in various sulfide minerals ( 206Pb 204Pb = 18.84 to 19.05; 207Pb 204Pb = 15.57 to 15.62; 208Pb 204Pb = 38.49 to 38.74), show less variation than data from the volcanic rocks of the Cascade Range and fall within the mixing array defined by the MORB regression line and continental sediments. An evaluation of the role of crustal assimilation by hydrothermal convection during emplacement was made on five sulfide deposits associated with a single composite batholith, the Cloudy Pass pluton. The Pb-isotopic data and mass balance calculations suggest that only minor amounts of the lead were derived from the overlying Precambrian (?) Swakane Biotite Gneiss during emplacement. The bulk of the metal that occurs in sulfide deposits in the Cascade mineral belt appears to have been derived from subducted continental detritus. The variation of the Pb-isotopic signature of Sulfides from specific districts or deposits suggests that there is a correlation with age and structure of the crust. 206Pb 204Pb is greater than 18.92 in northern Washington and southern Oregon where deposits have intruded Mesozoic or older crust. However, the ore deposits between the northern Oregon border and central Oregon, south of Eugene, have intruded younger crust composed largely of mafic and andesitic volcanic rocks and 206Pb 204Pb lies between 18.84 and 18.92. This region, previously called the Columbia embayment, appears to be underlain by Tertiary volcanic rocks. Lead-isotopic data may be used to define the boundaries between discontinuous blocks of Mesozoic crust and Tertiary volcanic cover. ?? 1986.

  1. Electronic inhomogeneity and Ag:Sb imbalance of Ag1-yPb18/207Sb1+zTe20 high-performance thermoelectrics elucidated by 125Te and 207Pb NMR

    SciTech Connect

    Levin, E.M.; Cook, B.A.; Ahn, K.; Kanatzidis, M.G.; Schmidt-Rohr, K.

    2009-09-22

    Using magic-angle spinning {sup 125}Te and {sup 207}Pb NMR, we have discovered the presence of two phases of approximately tenfold different free-electron concentration, n, in high-performance thermoelectrics Ag{sub 1?y}Pb{sub 18}Sb{sub 1+z}Te{sub 20} (LAST-18), proven by pairs of Knight-shifted NMR peaks and biexponential spin-lattice relaxation. The ratio of the phases is typically 2:1 with n {approx} 2 x 10{sup 19} cm{sup -3} and 0.2 x 10{sup 19} cm{sup -3}, respectively, determined from the spin-lattice relaxation times. {sup 125}Te NMR spectra show that both phases contain similar concentrations of Sb. The low-n component is assigned to Ag-rich regions with Ag-Sb pairing (but not AgSbTe{sub 2}), the dominant high-n component to PbTe:Sb resulting from the excess of Sb relative to Ag. The electronic inhomogeneity observed here must be considered in the search for a better understanding of high-performance thermoelectric materials.

  2. Isotopic Studies of the Guerrero Composite Terrane, West-Central Mexico: Implications for Provenance of Crustal Rocks and Ore Metals

    NASA Astrophysics Data System (ADS)

    Potra, A.; Macfarlane, A. W.; Salters, V. J.; Sachi-Kocher, A.

    2010-12-01

    New Pb, Sr, and Nd isotope analyses of various crustal units and ores from the Guerrero terrane are presented in order to gain insight into their provenance. Mesozoic basement rocks from the Arteaga Complex and Tejupilco metamorphic suite contain radiogenic Pb relative to bulk earth models (206Pb/204Pb between 18.701 and 19.256, 207Pb/204Pb between 15.623 and 15.693, and 208Pb/204Pb between 38.694 and 39.216), plotting to the right of the average Pb crust evolution curve of Stacey and Kramers (1975). The isotopic compositions of Pb in these rocks are substantially more radiogenic than published data on high-grade metamorphic rocks from the Grenvillian-age Oaxaca terrane, but are similar to Paleozoic basement rocks of the Mixteca terrane. Sr and Nd isotope data suggest that the basement rocks of the Guerrero terrane partly originated from ocean-floor rocks which were overlain by sediments derived from a cratonic terrane, possibly represented by the metamorphic complexes of the Oaxaca or Mixteca terranes. Lead isotope ratios of Cretaceous sedimentary rocks of the Zihuatanejo and Huetamo Sequences define two different clusters, with the Zihuatanejo Sequence units shifted to more radiogenic values (206Pb/204 between 18.763 and 19.437, 207Pb/204Pb between 15.580 and 15.643, and 208Pb/204Pb between 38.510 and 38.892). Samples from the Huetamo Sequence are less radiogenic than the metamorphic basement, with Pb isotope ratios between 18.630 and 18.998 for 206Pb/204, 15.563 and 15.641 for 207Pb/204Pb, and 38.369 and 38.610 for 208Pb/204Pb. They plot close to the radiogenic end of the MORB field, suggesting a possible mixing line between the basement rocks and the MORB component. Lead isotope ratios of Tertiary intrusive rocks from La Verde, El Malacate, and La Esmeralda resemble the orogene reservoir in the plumbotectonics model of Zartman and Doe (1981). Plutonic rocks from La Verde show the most radiogenic Pb compositions, suggesting a significant influence of old

  3. Two-types of Early Cretaceous adakitic porphyries from the Luxi terrane, eastern North China Block: Melting of subducted Paleo-Pacific slab and delaminated newly underplated lower crust

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Xu, Zhaowen; Lu, Xiancai; Fu, Bin; Lu, Jianjun; Yang, Xiaonan; Zhao, Zengxia

    2016-01-01

    The origin and tectonic setting of Early Cretaceous adakitic rocks from the Luxi terrane in the eastern North China Block (NCB) remain debated. To resolve this issue, we determined whole-rock geochemistry, zircon U-Pb ages, and in situ Hf-O isotopes of the Mengyin and Liujing adakitic porphyries from the Luxi terrane. Zircon U-Pb dating results reveal that both the Mengyin and Liujing plutons were emplaced during the Early Cretaceous, with weighted mean 206Pb/238U ages of 130 ± 1 Ma (2σ) and 131 ± 2 Ma (2σ), respectively. In addition, abundant Neoarchean-Paleoproterozoic inherited zircon cores are identified in the Mengyin adakitic porphyry with 207Pb/206Pb ages ranging from 2.53 to 2.42 Ga. Rocks of both plutons are silicic (SiO2 = 65.4-70.2 wt.%), metaluminous, and alkaline in composition, comprising mainly quartz syenite porphyries. Samples from both plutons are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Sr, and Ba), and light rare earth elements (LREEs), depleted in high field strength elements (HFSEs) (e.g., Nb, Ta, and Ti), and heavy rare earth elements (HREEs), and have either positive or no Eu anomalies. In addition, both adakitic porphyries have high Mg# values (51-64), high Sr and La contents, low Y and Yb contents, and high Sr/Y (Mengyin = 149-264; Liujing = 58-110) and (La/Yb)N (Mengyin = 32.4-45.3; Liujing = 43.8-53.1) ratios, similar to adakitic rocks worldwide. The Mengyin adakitic porphyry has higher whole-rock εNd(t) values (-5.8 to - 4.1), more radiogenic Pb [(206Pb/204Pb)i = 18.35-18.39, (207Pb/204Pb)i = 15.55-15.56, (208Pb/204Pb)i = 38.20-38.23], higher zircon rim εHf(t) values (+ 3.3 to + 8.8) and δ18O values (+ 6.5‰ to + 7.9‰), and lower (87Sr/86Sr)i ratios (0.7049-0.7050) than the Liujing adakitic porphyry [εNd(t) = - 12.4 to - 12.2, (206Pb/204Pb)i = 17.63-17.72, (207Pb/204Pb)i = 15.56-15.58, (208Pb/204Pb)i = 37.76-37.94, εHf(t) = - 14.8 to - 11.2, δ18O = + 5.9‰ to + 7.1‰, (87Sr/86Sr)i = 0.7090-0.7091]. The

  4. Pb and O isotopic constraints on the source of granitic rocks from Cape Breton Island, Nova Scotia, Canada

    USGS Publications Warehouse

    Ayuso, R.A.; Barr, S.M.; Longstaffe, F.J.

    1996-01-01

    Pb isotopic compositions of leached feldspars from twenty-three plutons in Cape Breton Island can be divided into two groups: anorthosite, syenite, and granite in the Blair River Complex, which have the least radiogenic compositions on the Island, and granitic rocks from terranes (Aspy, Bras d'Or, and Mira) to the south. Pb isotopic data for the Blair River Complex (206Pb/204Pb = 17.399-18.107; 207Pb/204Pb = 15.505-15.560; 208Pb/204Pb = 36.689-37.733) are consistent with an old source region ultimately derived from the mantle and contaminated by sialic crust. Oxygen isotopic compositions of syenite in the Blair River Complex (??18O = +8.0 to +8.5 permil) are slightly higher than anorthosite (+7.0 to +8.3 permil); a Silurian granite in the Blair River Complex has ??18O = +7.5 permil. Cambrian to Devonian plutons in the Aspy, Bras d'Or, and Mira terranes are more radiogenic (206Pb/204Pb = 18.192-18.981; 207Pb/204Pb = 15.574-15.712; 208Pb/ 204Pb =37.815-38.936) than the Blair River Complex and were generated from source regions having a predominant crustal Pb signature (high ??). The ??18O values of granites and granodiorites in the Aspy terrane (+7.5 to +9.2 permil; avg = +8.6 permil) and Bras d'Or (+3.7 to +11.3 permil; avg = +9.4 permil) are also consistent with involvement of sialic crust. Many Late Proterozoic granites from the Mira terrane have anomalously low ??18O values (+0.2 to +5.9 permil), perhaps produced from protoliths that had undergone hydrothermal alteration prior to melting. Paleozoic granitic rocks from the Aspy, Bras d'Or, and Mira terranes cannot be uniquely distinguished on the basis of their Pb and O isotopic compositions. The granitic rocks could have been generated during terrane amalgamation from combinations of unradiogenic (Grenville-like) and more radiogenic (Avalon-like) sources.

  5. Dust Deposition and Migration of the ITCZ through the Last Glacial Cycle in the Central Equatorial Pacific (Line Islands).

    NASA Astrophysics Data System (ADS)

    Reimi Sipala, M. A.; Marcantonio, F.

    2014-12-01

    Atmospheric dust can be used to record climate change in addition to itself playing a role in several key climate processes, such as affecting Earth's albedo, fomenting rain coalescence, encouraging biological productivity, and enhancing carbon export though particle sinks. Using deep sea sediments, it is possible to quantify and locate the sources and sinks of atmospheric dust. A key area of research is the shift in the inter-tropical converge zone (ITCZ), a thermally influenced area that shifts according to the northern and southern hemisphere temperature gradient. This ongoing project focuses on the changes of the ITCZ over the Central Equatorial Pacific (CEP) over the past ~25000 years. The research focuses on two cores taken from the Line Islands Ridge at 0° 29' N (ML1208-18GC), and 4° 41' N (ML1208-31BB). The main aim is to quantify the magnitude and provenance of windblown dust deposited in the CEP, and to address questions regarding the nature of the variations of dust through ice-age climate transitions. Radiogenic isotopes (Sr, Nd, Pb) have been successfully used to distinguish between different potential dust sources in the aluminosilicates fractions of Pacific Sediments. Our preliminary Pb isotope ratios suggest that, for modern deposition, the northern core's (31BB) detrital sediment fraction is likely sourced from Asian Loess (average ratios are 206Pb/204Pb = 18.88, 207Pb/204Pb = 15.69, 208Pb/204Pb = 39.06). The equatorial core's (18GC) detrital fraction has a less radiogenic Pb signature, which is consistent with South American dust sourcing (206Pb/204Pb = 18.62, 207Pb/204Pb = 15.63, 208Pb/204Pb = 38.62). This is indicative of a strong modern ITCZ that acts as an effective barrier for inter-hemispheric dust transport. Prior to Holocene time, the changes in Pb isotope ratios in both cores appear to be in anti-phase; the northern core becomes less radiogenic up to the LGM, while the southern core becomes more radiogenic. This is potentially due to a

  6. Geochemistry, Sr-Nd-Pb isotopes and geochronology of amphibole- and mica-bearing lamprophyres in northwestern Iran: Implications for mantle wedge heterogeneity in a palaeo-subduction zone

    NASA Astrophysics Data System (ADS)

    Aghazadeh, Mehraj; Prelević, Dejan; Badrzadeh, Zahra; Braschi, Eleonora; van den Bogaard, Paul; Conticelli, Sandro

    2015-02-01

    Lamprophyres of different age showing distinctive mineralogy, geochemistry and isotopic ratios are exposed in northwestern Iran. They can be divided into Late Cretaceous sannaite, Late Oligocene-Early Miocene camptonite (amphibole-bearing) and Late Miocene minette (mica-bearing) and spessartite (amphibole-bearing) lamprophyres. Sannaites have high-Ti amphibole along with high-Ti and Al clinopyroxene, and they are characterised by homogeneous enrichment in incompatible trace elements with troughs at Pb. Spessartites have hornblende and low-Al and Ti clinopyroxene, and they are characterised by enriched incompatible trace element pattern with depletions of Nb, Ta, Pb, and Ti with respect to large ion lithophile elements. Minettes have high-Ti and Al brown mica and low-Al and Ti clinopyroxene, and similar to spessartite, are characterised by fractionation of high field strength elements with respect to large ion lithophile elements, with troughs at Nb, Ta, and Ti and a peak at Pb. Minettes show high initial 87Sr/86Sr values up to 0.70760 and low initial 143Nd/144Nd down to 0.512463 with a negative correlation, consistent with the trace element distribution related with an enriched mantle source modified after sediment recycling during subduction and continental collision. Cretaceous sannaites and Early Miocene spessartites show low initial 87Sr/86Sr approaching 0.70447 and high 143Nd/144Nd values up to 0.512667, which are consistent with a depleted within-plate mantle source. Minette and spessartite lamprophyres show high initial 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values, whereas sannaites have lower, but variable, initial 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values with respect to those of calc-alkaline lamprophyres. Minettes originated by partial melting of a metasomatised lithospheric mantle following siliciclastic sediment recycling by subduction. In contrast, sannaites were generated from the partial melting of a similar lithospheric mantle that was

  7. Lead isotopic analyses of selected soil samples from the USEPA Vasquez Blvd.-I-70 study area, Denver, CO

    USGS Publications Warehouse

    Unruh, D.M.

    2002-01-01

    Large amounts of arsenic contamination, in excess of 2000 ppm, have been found in some residential surface soils in northern Denver, Colorado (USEPA, 1999). Associated with the arsenic are elevated levels of metals such as lead, cadmium and mercury. Potential sources of this contamination include waste from smelters in the area and commercial herbicide containing arsenic trioxide and lead arsenate (USEPA, 1999). As a part of the U.S. Environmental Protection Agency’s Vasquez Boulevard-I-70 Project (VBI70 project; USEPA, 1999), lead isotopic analyses of selected soil samples, smelter waste, and a commercial herbicide and a commercial lead arsenate pesticide have been performed in order to constrain the possible sources of elevated lead, and by proxy arsenic, found in these residential soils. The isotopes of lead can be used as a natural tracer in determining sources of contaminants in soils and stream sediments (e.g. Church and others, 1997; Fey and others, 1999; Unruh and others, 2000). The element lead (Pb) consists of four naturally occurring and stable isotopes, 204Pb, 206Pb, 207Pb, and 208Pb. Three of these, 206Pb, 207Pb, and 208Pb are radiogenic decay products of naturally occurring 238U, 235U, and 232Th, respectively. Owing to variations among the U/Pb and Th/Pb elemental abundance ratios among different types of geologic materials, variations in the relative abundances of the Pb isotopes are produced among different materials during geologic time. In order for the Pb isotope method to be useful for determining possible contaminant sources, two important criteria must be met (e.g. Church and others 1997): (1) It must be possible to obtain and measure the Pb isotopic compositions in all potential contaminant sources and in uncontaminated material and (2) the Pb isotopic compositions of the potential contaminant sources must be distinctly different from one another and from uncontaminated background. Variations among the Pb isotopic ratios in selected samples

  8. CONCH: A Visual Basic program for interactive processing of ion-microprobe analytical data

    NASA Astrophysics Data System (ADS)

    Nelson, David R.

    2006-11-01

    A Visual Basic program for flexible, interactive processing of ion-microprobe data acquired for quantitative trace element, 26Al- 26Mg, 53Mn- 53Cr, 60Fe- 60Ni and U-Th-Pb geochronology applications is described. Default but editable run-tables enable software identification of secondary ion species analyzed and for characterization of the standard used. Counts obtained for each species may be displayed in plots against analysis time and edited interactively. Count outliers can be automatically identified via a set of editable count-rejection criteria and displayed for assessment. Standard analyses are distinguished from Unknowns by matching of the analysis label with a string specified in the Set-up dialog, and processed separately. A generalized routine writes background-corrected count rates, ratios and uncertainties, plus weighted means and uncertainties for Standards and Unknowns, to a spreadsheet that may be saved as a text-delimited file. Specialized routines process trace-element concentration, 26Al- 26Mg, 53Mn- 53Cr, 60Fe- 60Ni, and Th-U disequilibrium analysis types, and U-Th-Pb isotopic data obtained for zircon, titanite, perovskite, monazite, xenotime and baddeleyite. Correction to measured Pb-isotopic, Pb/U and Pb/Th ratios for the presence of common Pb may be made using measured 204Pb counts, or the 207Pb or 208Pb counts following subtraction from these of the radiogenic component. Common-Pb corrections may be made automatically, using a (user-specified) common-Pb isotopic composition appropriate for that on the sample surface, or for that incorporated within the mineral at the time of its crystallization, depending on whether the 204Pb count rate determined for the Unknown is substantially higher than the average 204Pb count rate for all session standards. Pb/U inter-element fractionation corrections are determined using an interactive log e-log e plot of common-Pb corrected 206Pb/ 238U ratios against any nominated fractionation-sensitive species pair

  9. Modification of an oceanic plateau, Aruba, Dutch Caribbean: Implications for the generation of continental crust

    NASA Astrophysics Data System (ADS)

    White, R. V.; Tarney, J.; Kerr, A. C.; Saunders, A. D.; Kempton, P. D.; Pringle, M. S.; Klaver, G. T.

    1999-01-01

    The generation of the continental crust may be connected to mantle plume activity. However, the nature of this link, and the processes involved, are not well constrained. An obstacle to understanding relationships between plume-related mafic material and associated silicic rocks is that later tectonic movements are liable to obscure the original relationships, particularly in ancient greenstone belts. Studies of younger analogous regions may help to clarify these relationships. On the island of Aruba in the southern Caribbean, a sequence of partly deformed mafic volcanic rocks intruded by a predominantly tonalitic batholith is exposed. The mafic lavas show geochemical and isotopic affinities with other basaltic, picritic and komatiitic rocks that crop out elsewhere in the Caribbean—these are well documented as belonging to an 88-91 Ma plume-related oceanic plateau, which is allochthonous with respect to the Americas, and is thought to have been formed in the Pacific region. The ˜85 to ˜82 Ma tonalitic rocks share some geochemical characteristics (high Sr and Ba, low Nb and Y) with Archaean tonalite-trondhjemite-granodiorite (TTG) suites. Field relationships suggest that deformation of the plateau sequence, possibly related to collision with a subduction zone, was synchronous with intrusion of the Aruba batholith. New incremental heating 40Ar/ 39Ar dates, combined with existing palaeontological evidence, show that cooling of the batholith occurred shortly after eruption of the plateau basalt sequence. Sr-Nd isotopic data for both rock suites are uniform ( 87Sr/ 86Sr i≈0.7035 , ɛNd i≈+7), whereas Pb isotopes are more variable (Plateau sequence: 206Pb/ 204Pb =18.6-19.1 , 207Pb/ 204Pb =15.54-15.60 , 208Pb/ 204Pb =38.3-38.75 ; Aruba batholith: 206Pb/ 204Pb =18.4-18.9 , 207Pb/ 204Pb =15.51-15.56 , 208Pb/ 204Pb =38.0-38.5 ). This suggests that there has been a minor sedimentary input into the source region of the batholith. However, the limited time interval

  10. Lead Isotopic Compositions of the Endeavour Sulfides, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Labonte, F.; Hannington, M. D.; Cousens, B. L.; Blenkinsop, J.; Gill, J. B.; Kelley, D. S.; Lilley, M. D.; Delaney, J. R.

    2006-12-01

    32 sulfide samples from the main structures of the Endeavour vent field, Juan de Fuca Ridge, were analyzed for their Pb isotope composition. The samples were collected from 6 main vent fields between 1985 and 2005 and encompass a strike length of more than 15 km along the ridge crest. The sulfides are typical of black smoker deposits on sediment-starved mid-ocean ridges. Pb isotope compositions of the massive sulfides within the six hydrothermal fields vary within narrow ranges, with 206Pb/204Pb = 18.58 18.75, 207Pb/204Pb = 15.45 15.53 and 208Pb/204Pb = 37.84 38.10. A geographic trend is observed, with the lower Pb ratios restricted mostly to the northern part of the segment (Salty Dawg, Sasquatch and High Rise fields), and the higher Pb ratios restricted mostly to the southern part of the segment (Main Endeavour, Clam Bed and Mothra fields). Variations within individual fields are much smaller than those between fields, and variation within individual sulfide structures is within the uncertainty of the measurements. Therefore, it is unlikely that the ranges of Pb isotope compositions along the length of the segment reflect remobilization, replacement, and recrystallization of sulfides, as suggested for the observed Pb isotope variability in some large seafloor sulfide deposits. Instead, the differences in isotopic compositions from north to south are interpreted to reflect differences in the source rocks exposed to hydrothermal circulation of fluids below the seafloor. Possible sources of the somewhat more radiogenic Pb may be small amounts of buried sediment, either from turbidites or from hemipelagic sediment. This possibility is supported by high concentrations of CH4 and NHC4 found in the high-temperature vent fluids at the Main Endeavour Field, which are interpreted to reflect subseafloor interaction between hydrothermal fluids and organic material in buried sediments. However, the majority of the samples fall below and are approximately parallel to the

  11. Inter-Tropical Convergence Zone Shifts During the Last Glacial Cycle Near the Line Islands Ridge.

    NASA Astrophysics Data System (ADS)

    Reimi Sipala, M. A.; Marcantonio, F.

    2015-12-01

    This research focuses on the shift in the inter-tropical convergence zone (ITCZ) during the last glacial cycle. Deep sea sediments from the Central Equatorial Pacific (CEP) are used to quantify and isolate the sources and sinks of atmospheric dust. Dust records and influences climate affecting a wide range of process from Earth's Albedo to carbon export. Our aim is to determine the provenance of windblown dust deposited in the CEP near the Line Islands Ridge using radiogenic Nd and Pb isotopes, and to infer the location of the ITCZ and the changes of atmospheric transport through ice-age climate transitions. We focus on three cores from the CEP, along a meridional transect at approximately 160° W --- 0° 28' N (ML1208-17PC), 4° 41' N (ML1208-31BB), and 7 ° 2'N (ML1208-31BB). Radiogenic isotopes (Sr, Nd, Pb) have been successfully used to distinguish between different potential dust sources in the aluminosilicates fractions of Pacific Sediments. Our preliminary data suggest that the equatorial core (17PC) predominantly receives its dust from South America and South American volcanics South America (206Pb/204Pb = 18.62, 207Pb/204Pb = 15.63, 208Pb/204Pb = 38.62; ; ɛNd = ~ -5). The middle core, which more closely reflects the modern position of the ITCZ, has varied dust provenance through time, at times consistent with Asian Loess (average ratios are 206Pb/204Pb = 18.88, 207Pb/204Pb = 15.69, 208Pb/204Pb = 39.06; ɛNd = ~ -7) and Asian Volcanics (ɛNd = ~-1) suggesting a shift in the ITCZ south of 4N before the LGM. Our results for the most northern core are forthcoming. Prior to Holocene time, the changes in Pb isotope ratios in both cores appear to be in anti-phase; the northern core becomes less radiogenic up to the LGM, while the southern core becomes more radiogenic. This is potentially due to a weakening of the ITCZ during glacial times. A secondary aim of this work is to determine if the ITCZ migrated further south than core 17PC during Heinrich stage II.

  12. Lead Isotope Constraints on the Sources of Ore Metals in SW Mexican Deposits

    NASA Astrophysics Data System (ADS)

    Potra, A.; Macfarlane, A. W.

    2007-12-01

    the field defined by the sedimentary rocks. Whereas the metamorphic and igneous rocks analyzed so far plot generally above the Stacey-Kramers (1975) reference line, the ores and sedimentary rocks define a narrow field just below this line. The distribution of data from these ores on co-variation diagrams also appears to define a steep array, suggesting a MORB-EPR source contaminated with a 207Pb- and 208Pb-rich component (possibly the metamorphic basement or a sedimentary component). The analyzed sedimentary rocks are less radiogenic than the metamorphic basement, suggesting they are not simply derived from the basement and that other rocks were involved in their provenance.

  13. Pb isotope geochemistry of Piton de la Fournaise historical lavas

    NASA Astrophysics Data System (ADS)

    Vlastélic, Ivan; Deniel, Catherine; Bosq, Chantal; Télouk, Philippe; Boivin, Pierre; Bachèlery, Patrick; Famin, Vincent; Staudacher, Thomas

    2009-07-01

    erupted between the two major refilling events of March 1986 and February 2005 (0.28 km 3) could provide a realistic estimate of the magma reservoir size. Unradiogenic anomalies appear to be linked, more or less directly, to the eruption of olivine-rich lavas. The related samples have low 206Pb/ 204Pb and 208Pb/ 204Pb but normal 207Pb/ 204Pb, suggesting a recent decrease of U/Pb and Th/Pb, for instance through sequestration of Pb into sulfides. Olivine and sulfides, which are both denser than silicate melts, could be entrained with magma pulses, which give rise to high-flux oceanite eruptions.

  14. Source of lead in Central American and Caribbean mineralization, II. Lead isotope provinces

    NASA Astrophysics Data System (ADS)

    Cumming, George L.; Kesler, Stephen E.; Krstic, Dragan

    1981-12-01

    In an earlier study of Mesozoic and Cenozoic mineralization in Central America and the Caribbean region, we found that lead isotopic compositions of deposits in northern Central America, which is underlain by a pre-Mesozoic craton, ranged to higher 206Pb/ 204Pb and 207Pb/ 204Pb compositions than did deposits from elsewhere in the region, where the basement is Mesozoic oceanic material. Using 16 analyses for 12 new deposits, as well as new analyses for 11 of the samples studied previously, we have found that lead isotopic compositions correlate closely with crustal type but show little or no correlation with depth to the M-discontinuity. The deposits are divisible into three main groups including (in order of increasing 207Pb/ 204Pb and 208Pb/ 204Pb ratio): (1) deposits in southern Central America and all deposits in the Greater Antilles except Cuba; (2) all deposits in northern Central America; and (3) the Cuban deposits. Southern Central American and Caribbean lead is higher in 207Pb/ 204Pb and 208Pb/ 204Pb than most mid-ocean ridge basalts but could have been derived directly or indirectly from undepleted mantle. Northern Central America can be divided into the Maya block, which belongs to the Americas plate, and the Chortis block, which belongs to the Caribbean plate. Maya block deposits fall along a linear array whereas those of the Chortis block (except the Monte Cristo deposit) form a cluster. These results suggest that the Maya block is underlain by crust or mantle with a large range of U/Pb and Th/U ratios, whereas the Chortis block basement is more homogeneous. Two-stage model calculations indicate an age of about 2280±310 m.y. for the Maya block basement, although no such rocks are known in the region. Comparison of the Chortis block data to our recently published lead isotopic analyses of Mexican deposits shows considerable similarities suggesting that the Chortis block could have been derived from Mexico.

  15. A lead isotope study of mineralization in the Saudi Arabian Shield

    USGS Publications Warehouse

    Stacey, J.S.; Doe, B.R.; Roberts, R.J.; Delevaux, M.H.; Gramlich, J.W.

    1980-01-01

    New lead isotope data are presented for some late Precambrian and early Paleozoic vein and massive sulfide deposits in the Arabian Shield. Using the Stacey Kramers (1975) model for lead isotope evolution, isochron model ages range between 720 m.y. and 420 m.y. Most of the massive sulfide deposits in the region formed before 680 m.y. ago, during evolution of the shield. Vein type mineralization of higher lead content occurred during the Pan African event about 550 m.y. ago and continued through the Najd period of extensive faulting in the shield that ended about 530 m.y. ago. Late post-tectonic metamorphism may have been responsible for vein deposits that have model ages less than 500 m.y. Alternatively some of these younger model ages may be too low due to the mineralizing fluids acquiring radiogenic lead from appreciably older local crustal rocks at the time of ore formation. The low207Pb/204Pb ratios found for the deposits in the main part of the shield and for those in north-eastern Egypt, indicate that the Arabian craton was formed in an oceanic crustal environment during the late Precambrian. Involvement of older, upper-crustal material in the formation of the ore deposits in this part of the shield is precluded by their low207Pb/204Pb and208Pb/204Pb characteristics. In the eastern part of the shield, east of longitude 44??20???E towards the Al Amar-Idsas fault region, lead data are quite different. They exhibit a linear207Pb/204Pb-206Pb/204Pb relationship together with distinctly higher208Pb/204Pb characteristics. These data imply the existence of lower crustal rocks of early Proterozoic age that apparently have underthrust the shield rocks from the east. If most of the samples we have analyzed from this easterly region were mineralized 530 m.y. ago, then the age of the older continental rocks is 2,100??300 m.y. (2??). The presence of upper crustal rocks, possibly also of early Proterozoic age, is indicated by galena data from Hailan in South Yemen and also

  16. Lead Isotopic Source Signatures for Rains and River Waters in Taiwan

    NASA Astrophysics Data System (ADS)

    You, C.; Cheng, M.; Lee, M.; Lin, F.

    2002-12-01

    Lead isotopic compositions and Pb contents in rains and river waters are sensitive proxies for air-pollutant sources and their transport processes. We have collected more than 100 wet precipitations between 1998 and 2001 at Peng-Chia Yu, an offshore island in northern Taiwan, and two other cities, Taichung and Tainan, located at central and southern Taiwan. Additional 14 river waters collected along the Er-Ren-Shi River, Tainan were investigated for systematic comparison. All collected samples were analyzed for major ions (i.e., Cl, Na, Mg, Ca, SO4, NO3 and NH4) by ion chromatography, trace elements and Pb isotopes by ICP-MS (Element II) installed at NCKU. The Peng-Chia Yu rains show large seasonal variation in major ions where Na and Cl are much higher in the winter season. Significant industrial contributions of SO4, NH4 and nsCa are detected at Taichung and Tainan. Trace element results display a more complicated picture, suggesting mixing among seasalt, Asia continental dust, and atmospheric pollutant. These chemical data can be understood in terms of seasonal wind direction changes due to the Asian monsoon system. In winter, the northerly cold wind blow materials with high concentration of anthropogenic input (i.e., Pb and SO4) and dust source (i.e., Al and Ca) from the Asia continent. In contrast, the intertropical convergence zone (ITCZ) migrates northward and caused southwest monsoon prevail in the summer. The 208Pb/207Pb ratio shows consistent seasonal trends as that of Pb contents, possibly a result of mixing between Asia atmospheric sources and seasalt. For the Er-ren Shi River waters, Pb and Pb isotopic compositions vary systematically downstream. Pb concentrations decrease rapidly from 5200 ppt at upstream stations to a value of less than 50 ppt near the estuary whereas 208Pb/207Pb varied between 2.087 and 2.124. The 208Pb/206Pb vs. 1/Pb plot demonstrates a mixing trend between anthropogenic sources and seawater. These results demonstrate that Pb and

  17. Accessory Mineral U-Pb Ti-Zr Thermochronology of the Deep Crust of Zealandia: Rift, Breakup and Drift from 90-20 Ma

    NASA Astrophysics Data System (ADS)

    Beinlich, A.; Palin, J.; Cooper, A. F.

    2006-12-01

    Cenozoic alkaline mafic volcanics of eastern Otago were made famous in classic petrology and petrography texts coauthored by Francis Turner. Several locales have yielded mantle and crustal xenoliths including the Pigroot "mafic phonolite". Here, among abundant spinel lherzolite xenoliths, we discovered an undeformed cumulate gabbro composed of intermediate plagioclase and pargasitic amphibole with augite, ilmenite, magnetite, titanite (sphene) and accessory zircon and apatite. Major and trace elements indicate the rock crystallised from primitive alkaline magma, whereas the mineral assemblage indicates equilibration under amphibolite facies conditions at 5-9 kbar. Accessory mineral U-Pb Ti-Zr thermochronology by LA-ICP-MS on grain separates and in thin section reveals a T-t path that began with zircon crystallisation at 90±2 Ma (^{208}Pb-corrected 206Pb/238U, n=37, mswd=9.9) and 710±20°C (Ti-zircon geothermometer of Watson et al. 2006). Titanite dates (207Pb-corrected 206Pb/238U, n=49) and temperatures (Zr-titanite geothermometer of Hayden et al. 2006 at 7 kbar) form a linear array (r2=0.6) extending from 85 Ma, 830°C to 34 Ma, 760°C. The slope of this T-t array is inconsistent with diffusive loss of Pb and Zr from titanite (Cherniak, pers.comm.) and, together with REE data and reaction textures, indicates prolonged growth at the expense of plagioclase and ilmenite. Apatite U-Pb isotope data projected from the measured 207Pb/206Pb in plagioclase give a lower intercept age of 20±3 Ma (n=17, mswd=1.5) which overlaps the K-Ar age of the phonotephrite host lava (Coombs, pers.comm.). This remarkable xenolith records 1) crystallisation of alkaline mafic magma in the deep crust during early rifting of Zealandia from Gondwana around 90 Ma, 2) heating during continued lithospheric thinning 90-85 Ma, 3) slow cooling (≤2°C/my) for 50 my following continental breakup at 85 Ma, and 4) transport to the surface and thermal quenching at 20 Ma. Slow cooling of the deep

  18. Geological, rare earth elemental and isotopic constraints on the origin of the Banbanqiao Zn-Pb deposit, southwest China

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhou, Jia-Xi; Huang, Zhi-Long; Yan, Zai-Fei; Bao, Guang-Ping; Sun, Hai-Rui

    2015-11-01

    The newly discovered Banbanqiao Zn-Pb deposit in the southeastern part of the Sichuan-Yunnan-Guizhou (SYG) Pb-Zn metallogenic province is located on the western Yangtze Block, southwest China. Ore bodies of the Banbanqiao deposit are stratiform type, host in dolomitic limestone and dolostone of the Lower Carboniferous Dapu Formation and occur within the NNE-trending Banbanqiao anticline. More than 1.5 million tones (Mt) Zn-Pb ores at grades of 0.26-10.32 wt.% Pb and 0.81-28.8 wt.% Zn have been controlled until now. δ13CPDB and δ18OSMOW values of calcite separates range from -2.8‰ to -0.7‰ (average -1.1‰) and +14.1‰ to +17.0‰ (average +15.5‰), respectively. The δ13CPDB values are similar to those of marine carbonate rocks, but higher than those of mantle and significantly different from those of sedimentary organic matter. However, the δ18OSMOW values are among those of mantle, marine carbonate rocks and sedimentary organic matter. δ34SCDT values of sulfide separates range from +3.2‰ to +9.9‰ (average +6.5‰), unlike mantle-derived sulfur (0 ± 3‰), whilst lower than evaporites (+22‰ to +28‰) within host strata. 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values of country shale and dolostone whole-rock samples are 18.47, 15.66 and 38.70, and 18.44-18.60, 15.66-15.85 and 38.70-39.14, respectively. Sulfide separates have 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values ranging from 18.03 to 18.73, 15.65 to 15.78 and 38.15 to 39.14, respectively. These Pb isotopic data indicate a clearly crustal source of Pb in the plot of 207Pb/204Pb vs. 206Pb/204Pb. Total REE (ΣREE) contents of country shale and dolostone whole-rock samples are 2.63 ppm and 0.72-86.2 ppm with δEu values are 2.79 and 0.34-0.70, respectively. Pyrite, sphalerite, galena and calcite samples have ΣREE contents of 5.3-36.4 ppm, 0.29-3.39 ppm, 0.52 ppm and 22.0-41.1 ppm, respectively, and δEu values of 0.64-0.86, 0.94-2.86, 0.32 and 0.21-0.45, respectively. These rare earth

  19. Petrogenesis of synorogenic diorite-granodiorite-granite complexes in the Damara Belt, Namibia: Constraints from U-Pb zircon ages and Sr-Nd-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Jung, S.; Kröner, A.; Hauff, F.; Masberg, P.

    2015-01-01

    The synorogenic Palmental complex (central Damara Belt, Nambia) consists of ca. 545 Ma old quartz diorites and rare granodiorites and ca. 520 Ma-old leucogranites, representing one of the earliest and most primitive phase of crustal plutonism predating the main high-T regional metamorphism. Most quartz diorites and one granodiorite evolved through multistage, polybaric evolutionary processes involving fractionation from a lithospheric mantle-derived melt, followed by fractional crystallization of mainly hornblende, plagioclase and apatite which is shown by decreasing MgO, FeO, CaO, TiO2 and P2O5 with increasing SiO2. Assimilation of felsic basement gneisses was also important during formation of these granitoids. Although their chemical characteristics (high LILE, low HFSE) resemble those of quartz diorites and granodiorites with calc-alkaline affinity, they differ in their enriched Sr (initial 87Sr/86Sr: 0.7061-0.7098) and Nd (initial εNd: -2.7 to -9.9) isotopic composition. Neodymium depleted mantle mean crustal residence ages range from 1.3 to 1.9 Ga for the quartz diorites including the granodiorite. These model ages correlate with major and trace element abundances, further substantiating that AFC processes modified the initial isotopic systematics. Lead (206Pb/204Pb: 17.43-17.68, 207Pb/204Pb: 15.61-15.66, 208Pb/204Pb: 38.19-38.49) isotopic composition are unradiogenic relative to other Damaran intrusive rocks but plot above the Stacey and Kramers (1975) reference line, indicating that the source underwent an ancient (pre Pan-African) increase in U/Pb and Th/U, followed by more recent U-depletion. Some variation in 206Pb/204Pb at high 207Pb/204Pb further indicates involvement of ancient crustal material, most likely through AFC processes. A cross-cutting leucogranite dyke has also evolved isotopic compositions (initial 87Sr/86Sr: 0.7326; initial εNd: -15.6; 206Pb/204Pb: 17.42, 207Pb/204Pb: 15.62, 208Pb/204Pb: 38.16) but in view of the apparent younger age of

  20. Pb isotopic study on soils from Domizio-Flegreo Littoral area, Napoli, Italy

    NASA Astrophysics Data System (ADS)

    Grezzi, G.; Ayuso, R. A.; Lima, A.; Albanese, S.; de Vivo, B.

    2009-04-01

    The Domizio - Flegreo Littoral area, together with the Agro Aversano area, are part of a Site of National Interest for pollution assessment. This area is located along the north coastal zone of the Campania region (Italy) and has an extension of about 855 Km2. We analyzed soils for heavy metal content in order to study and discriminate the impact of natural and anthropogenic sources. We collected 292 soil surface samples (5-15 cm depth) and produced maps showing the distribution of heavy metals in the soils. On the basis of the geographic distribution of heavy metals, 9 soil profiles were also collected for detailed examination (1 meter from surface). From each soil profile, we collected 10 soil samples (1/10 cm) in the urban and suburban areas of the littoral area. Also, we collected 8 groundwater samples likely associated with the soils. Pb isotope compositions of these soils and waters help to constrain the impact of anthropogenic and natural components on the soil profiles. Possible anthropogenic end-members include pesticides used in the area. Lead isotope compositions of soils known to contain anomalously high values of heavy metals were measured in order to determine the sources of the Pb and, by inference, sources of other metals that are likely to share similar geochemical behaviour in the surface environment (e.g., As). Acid-leach compositions of the soils represent Pb that is adsorbed to mineral surfaces, whereas residue compositions may reflect bedrock. Labile Pb (acid-leach fractions) from the soils shows a range in compositions of 207Pb/206Pb = 0.8275 to 0.8486, and 208Pb/206Pb = 2.0488 to 2.0873. The isotope values vary and decrease with depth. The Pb isotope ratios obtained on groundwater samples range from about 207Pb/206Pb = 0.8516 to 0.8636, 208Pb/206Pb = 2.0706 to 2.1064. The Pb isotope ratios in the soil profiles and groundwater are generally consistent with multiple sources that include anthropogenic Pb. Surface soil samples from Giugliano

  1. Isotope systematic of contaminant leads in Monterey Bay

    SciTech Connect

    Flegal, A.R.; Rosman, K.J.R.; Stephenson, M.D.

    1987-11-01

    Isotopic compositions of stable lead (/sup 204/Pb, /sup 206/Pb, /sup 207/Pb, and /sup 208/Pb) were utilized to identify a lead slag deposit as the principal source of contaminant lead in Monterey Bay. This point source had been indicated by anomalously high lead concentrations in native mussels (Mytilus californianus) near that deposit, which were orders of magnitude above the base-line concentration of the species (0.5 ..mu..g/g). Subsequent analyses revealed that the lead concentrations of both transplanted mussels and intertidal sediments were positively correlated with their proximity to the slag deposit. Complementary lead isotopic compositions substantiated those empirical correlations by demonstrating that the slag was the predominant source of contaminant lead in both the mussels and the sediments. Analyses of the digestive tracts of mussels from the slag deposit indicated that ingested slag particulates accounted for their elevated lead concentrations, while analyses of their gonads indicated that dissolved lead from other industrial sources was also being bioaccumulated by passive adsorption on exposed surfaces. Therefore, this study has demonstrated the potential of lead isotope systematics both to identify sources of lead contamination in marine organisms and to trace its biogeochemical cycle in the marine environment. 26 references, 3 figures, 5 tables.

  2. Lead isotopes in lichen transplants around a Cu smelter in Russia determined by MC-ICP-MS reveal transient records of multiple sources.

    PubMed

    Spiro, B; Weiss, D J; Purvis, O W; Mikhailova, I; Williamson, B J; Coles, B J; Udachin, V

    2004-12-15

    Transplants of the lichen Hypogymnia physodes, which is relatively tolerant to SO2 and heavy metals, were deployed for 3 months over a 60 km long SW-NE transect centered on a highly polluting Cu smelter and its adjoining town of Karabash, southern Urals, Russia. The abundance of 206Pb, 207Pb, 208Pb, and 204Pb were determined by MC-ICP-MS. The measurement of 204Pb revealed critical features, which would otherwise remain concealed: (i) The precise isotope ratios referenced to 204Pb allowed several different sources to be resolved even within the small area covered: (a) the obvious pollutant source of the Karabash Cu smelter; (b) two dispersed sources, likely to include soil with lower and different contributions of thorogenic and uranogenic lead; and (c) one anthropogenic source with higher contribution of 235U derived Pb. (ii) In part of the transect, the Pb isotope composition changed while the Pb concentrations remained the same. This indicates that the Pb content of the transplantation material from the background site was largely replaced and that the transplants provide a transient record reflecting a continuous accumulation and loss of environmental Pb, probably mainly in the form of extracellular particles. Overall, the method of lichen transplantation coupled with Pb isotope ratio determinations proved effective in assessing the usefulness of lichens in biomonitoring and in resolving different sources of atmospheric deposition.

  3. A LREE-depleted component in the Afar plume: Further evidence from Quaternary Djibouti basalts

    NASA Astrophysics Data System (ADS)

    Daoud, Mohamed A.; Maury, René C.; Barrat, Jean-Alix; Taylor, Rex N.; Le Gall, Bernard; Guillou, Hervé; Cotten, Joseph; Rolet, Joël

    2010-02-01

    Major, trace element and isotopic (Sr, Nd, Pb) data and unspiked K-Ar ages are presented for Quaternary (0.90-0.95 Ma old) basalts from the Hayyabley volcano, Djibouti. These basalts are LREE-depleted (La n/Sm n = 0.76-0.83), with 87Sr/ 86Sr ratios ranging from 0.70369 to 0.70376, and rather homogeneous 143Nd/ 144Nd ( ɛNd = + 5.9-+ 7.3) and Pb isotopic compositions ( 206Pb/ 204Pb = 18.47-18.55, 207Pb/ 204Pb = 15.52-15.57, 208Pb/ 204Pb = 38.62-38.77). They are very different from the underlying enriched Tadjoura Gulf basalts, and from the N-MORB erupted from the nascent oceanic ridges of the Red Sea and Gulf of Aden. Their compositions closely resemble those of (1) depleted Quaternary Manda Hararo basalts from the Afar depression in Ethiopia and (2) one Oligocene basalt from the Ethiopian Plateau trap series. Their trace element and Sr, Nd, Pb isotope systematics suggest the involvement of a discrete but minor LREE-depleted component, which is probably an intrinsic part of the Afar plume.

  4. Lead and strontium isotope data for thermal waters of the regional geothermal system in the Twin Falls and Oakley areas, South-Central Idaho

    SciTech Connect

    Mariner, R.H.; Young, H.W.

    1995-12-31

    Thermal fluids obviously related to aquifers in both rhyolite and limestone occur in the Twin Falls-Oakley area of south-central Idaho. Limestone-related waters (high calcium with low silica and fluoride) occur in the middle and upper (southern) parts of the area. Rhyolite-related waters (low calcium but high in silica and fluoride) occur in the lower (northern) part of the area. The relation of thermal fluids in Paleozoic limestone to thermal fluids in Tertiary rhyolite is unknown. Thermal fluids from limestone are dilute, so water-rock reaction in rhyolite could obliterate chemical evidence of fluid residence in a limestone. However, isotopic tracers such as {sup 206}Pb/{sup 204}Pb, {sup 207}Pb/{sup 204}Pb, {sup 208}Pb/{sup 204}Pb, and {sup 87}Sr/{sup 86}Sr might preserve evidence of fluid residence in limestone. Systematic relations between these isotopes and dissolved constituents in the water demonstrate the presence of limestone beneath most if not all of the study area and that aquifers in the limestone and rhyolite are hydrologically connected.

  5. Rb-Sr whole-rock and mineral ages, K-Ar, 40Ar/39Ar, and U-Pb mineral ages, and strontium, lead, neodymium, and oxygen isotopic compositions for granitic rocks from the Salinian Composite Terrane, California:

    USGS Publications Warehouse

    Kistler, R.W.; Champion, D.E.

    2001-01-01

    This report summarizes new and published age and isotopic data for whole-rocks and minerals from granitic rocks in the Salinian composite terrane, California. Rubidium-strontium whole-rock ages of plutons are in two groups, Early Cretaceous (122 to 100 Ma) and Late Cretaceous (95 to 82 Ma). Early Cretaceous plutons occur in all granitic rock exposures from Bodega Head in the north to those from the Santa Lucia and Gabilan Ranges in the central part of the terrane. Late Cretaceous plutons have been identified in the Point Reyes Peninsula, the Santa Lucia and the Gabilan Ranges, and in the La Panza Range in the southern part of the terrane. Ranges of initial values of isotopic compositions are 87Sr/86Sr, 0.7046-0.7147, δ18O, +8.5 to +12.5 per mil, 206Pb/204Pb, 18.901-19.860, 207Pb/204Pb, 15.618-15.814, 208Pb/204Pb, 38.569- 39.493, and εNd, +0.9 to -8.6. The initial 87Sr/86Sr=0.706 isopleth is identified in the northern Gabilan Range and in the Ben Lomond area of the Santa Cruz Mountains, in Montara Mountain, in Bodega Head, and to the west of the Farallon Islands on the Cordell Bank. This isotopic boundary is offset about 95 miles (160km) by right-lateral displacements along the San Gregorio-Hosgri and San Andreas fault systems.

  6. Lead isotopic composition of paleozoic and late proterozoic marine carbonate rocks in the vicinity of Yucca Mountain, Nevada

    USGS Publications Warehouse

    Zartman, Robert E.; Kwak, Loretta M.

    1993-01-01

    Paleozoic and Late Proterozoic marine carbonate rocks (limestones, dolomites, and their metamorphic equivalents) cropping out in the vicinity of Yucca Mountain contain lead with an isotopic composition strongly suggesting them to be a major source of the lead observed at Trench 14 in the carbonate phase of carbonate-silica veins and nearby surficial calcrete deposits. Six whole-rock samples of marine carbonate rocks yield 206Pb/204Pb = 19.21-29.06, 207Pb/204Pb = 15.74-16.01, and 208Pb/204Pb = 37.90-39.25, and leachate and residue fractions of the rocks reveal additional isotopic heterogeneity within individual samples. Two samples of eolian dust also have isotopic compositions lying along a 'carbonate' to 'silicate' mixing trend that appears to arise entirely from pedogenic processes. The tendency for the marine carbonate rocks to evolve highly uranogenic, but no thorogenic, lead results in a distinctive isotopic composition that serves as a tracer in eolian dust and secondary carbonate minerals derived from the marine carbonate rocks.

  7. Enriched Nd-Sr-Pb isotopic signatures in the Dovyren layered intrusion ( eastern Siberia, Russia): Evidence for source contamination by ancient upper-crustal material

    USGS Publications Warehouse

    Amelin, Yu. V.; Neymark, L.A.; Ritsk, E. Yu; Nemchin, A.A.

    1996-01-01

    Major- and trace-element concentrations and Nd-, Sr- and Pb-isotopic ratios are reported for the Dovyren layered mafic-ultramafic intrusion in the northern Baikal region, eastern Siberia. Sm-Nd internal isochrons for an olivine gabbro from the layered series and a gabbronorite from a sill at the bottom of the Dovyren intrusion yield ages of 673 ?? 22 and 707 ?? 40 Ma, respectively. Initial isotopic ratios: 87Sr/86Sr (673) from 0.7101 to 0.7135, ??Nd(673 Ma) from - 16.3 to - 14.1, 206Pb/204Pb from 16.80 to 17.14, 207Pb/204Pb from 15.477 to 15.501 and 208Pb/204Pb from 37.17 to 37.59, are similar to those of late Archean-early Proterozoic upper continental crust, but do not appear to be a result of wallrock assimilation in the magma chamber. These isotopic features, as well as high K, Rb and LREE and low Ti concentrations in the calculated composition of the Dovyren parental magma, may be explained by subduction of sediments derived from upper continental crust into depleted mantle and subsequent melting of the metasomatized peridotite.

  8. Coupling of Uranium and Thorium Series Isotope Systematics for Age Determination of Late Pleistocene Zircons using LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Sakata, S.; Hirakawa, S.; Iwano, H.; Danhara, T.; Hirata, T.

    2014-12-01

    Zircon U-Th-Pb dating method is one of the most important tools for estimating the duration of magmatism by means of coupling of uranium, actinium and thorium decay series. Using U-Pb dating method, its reliability is principally guaranteed by the concordance between 238U-206Pb and 235U-207Pb ages. In case of dating Quaternary zircons, however, the initial disequilibrium effect on 230Th and 231Pa should be considered. On the other hands, 232Th-208Pb dating method can be a simple but powerful approach for investigating the age of crystallization because of negligible influence from initial disequilibrium effect. We have developed a new correction model for accurate U-Pb dating of the young zircon samples by taking into consideration of initial disequilibrium and a U-Pb vs Th-Pb concordia diagram for reliable age calibration was successfully established. Hence, the U-Th-Pb dating method can be applied to various zircons ranging from Hadean (4,600 Ma) to Quaternary (~50 ka) ages, and this suggests that further detailed information concerning the thermal history of the geological sequences can be made by the coupling of U-Th-Pb, fission track and Ar-Ar ages. In this presentation, we will show an example of U-Th-Pb dating for zircon samples from Sambe Volcano (3 to 100 ka), southwest Japan and the present dating technique using LA-ICP-MS.

  9. Detrital Zircon U-Pb Geochronology Applied to Tectonics

    NASA Astrophysics Data System (ADS)

    Gehrels, George

    2014-05-01

    Detrital zircon geochronology is rapidly developing into an essential tool in Earth science research because of the widespread occurrence of zircon in sedimentary systems; the wide range of information that can be extracted from zircon crystals; the ability to determine ages with reasonable precision, accuracy, and efficiency; and the wide range of new ideas about how to use detrital zircon geochronologic information. The U-Pb system is particularly powerful because three chronometers are available (238U+206Pb, 235U+207Pb, and 232Th+208Pb), but challenges arise because of complexities from inheritance and Pb loss. Ages can be used to constrain the age of deposition of the host sediment, reconstruct provenance, characterize a sedimentary unit, and characterize many different aspects of source regions. Detrital zircon geochronology has an exciting future given the growth history recorded in individual crystals; the variety of detrital minerals that can provide complementary information; and the large number of geochemical, isotopic, and chronologic systems that can be applied to these minerals.

  10. [High-precision in situ analysis of the lead isotopic composition in copper using femtosecond laser ablation MC-ICP-MS and the application in ancient coins].

    PubMed

    Chen, Kai-Yun; Fan, Chao; Yuan, Hong-Lin; Bao, Zhi-An; Zong, Chun-Lei; Dai, Meng-Ning; Ling, Xue; Yang, Ying

    2013-05-01

    In the present study we set up a femtosecond laser ablation MC-ICP-MS method for lead isotopic analysis. Pb isotopic composition of fifteen copper (brass, bronze) standard samples from the National Institute of Standards Material were analyzed using the solution method (MC-ICP-MS) and laser method (fLA-MC-ICPMS) respectively, the results showed that the Pb isotopic composition in CuPb12 (GBW02137) is very homogeneous, and can be used as external reference material for Pb isotopic in situ analysis. On CuPb12 112 fLA-MC-ICPMS Pb isotope analysis, the weighted average values of the Pb isotopic ratio are in good agreement with the results analyzed by bulk solution method within 2sigma error, the internal precision RSEs of the 208 Pb/204 Pb ratio and 207 Pb/206 Pb ratio are less than 90 and 40 ppm respectively, and the external precision RSDs of them are less than 60 and 30 ppm respectively. Pb isotope of thirteen ancient bronze coins was analyzed via fLA-MC-ICPMS, the results showed that the Pb isotopic composition of ancient coins of different dynasties is significantly different, and not all the Pb isotopic compositions in the coins even from the same dynasty are in agreement with each other.

  11. Determination of trace element concentrations and stable lead, uranium and thorium isotope ratios by quadrupole-ICP-MS in NORM and NORM-polluted sample leachates.

    PubMed

    Mas, J L; Villa, M; Hurtado, S; García-Tenorio, R

    2012-02-29

    This work focuses on the monitoring of the potential pollution in scenarios that involve NORM-related industrial activities (environmental or in-door scenarios). The objective was to develop a method to determine extent and origin of the contamination, suitable for monitoring (i.e. simple, fast and economical) and avoiding the use of too many different instruments. It is presented a radiochemical method that allows the determination of trace element concentrations and 206Pb/207Pb/208Pb, 238U/234U and 232Th/230Th isotope ratios using a single sample aliquot and a single instrument (ICP-QMS). Eichrom UTEVA® extraction chromatography minicolumns were used to separate uranium and thorium in sample leachates. Independent ICP-MS determinations of uranium and thorium isotope ratios were carried out afterwards. Previously a small aliquot of the leachate was used for the determination of trace element concentrations and lead isotope ratios. Several radiochemical arrangements were tested to get maximum performances and simplicity of the method. The performances of the method were studied in terms of chemical yields of uranium and thorium and removal of the potentially interfering elements. The established method was applied to samples from a chemical industry and sediments collected in a NORM-polluted scenario. The results obtained from our method allowed us to infer not only the extent, but also the sources of the contamination in the area.

  12. Tracking lead origin in the Yellow River Estuary and nearby Bohai Sea based on its isotopic composition

    NASA Astrophysics Data System (ADS)

    Hu, Ning-jing; Huang, Peng; Liu, Ji-hua; Shi, Xue-fa; Ma, De-yi; Zhu, Ai-mei; Zhang, Jun; Zhang, Hui; He, Lian-hua

    2015-09-01

    The Pb concentration and Pb isotopes (204Pb, 206Pb, 207Pb, and 208Pb) in surface sediments from the Yellow River Estuary and nearby Bohai Sea have been determined to investigate the Pb sources in this area. Results showed that Pb in the Yellow River Estuary and northern Laizhou Bay (YRE-NL) sediments was mainly from the Yellow River catchment as a consequence of lithogenic sediments (from rock weathering) accumulation. However, Pb in the coastal area of southern Laizhou Bay (CSLB) sediments was from both natural and anthropogenic sources. Sewage discharged near the Mihe mouth of the CSLB did not extend further to the middle and outer shelves because of the current in Laizhou Bay. The total Pb concentration varied from 14.5 to 30.4 μg/g with an average concentration of 20.1 ± 4.2 μg/g. Thus, significant Pb pollution was not observed in the Yellow River Estuary and nearby Bohai Sea. However, Pb contamination in some sites was indicated by Pb isotope ratios.

  13. Pb isotopic heterogeneity in basaltic phenocrysts

    SciTech Connect

    Bryce, Julia G.; DePaolo, Donald J.

    2002-06-01

    The Pb isotopic compositions of phenocrystic phases in young basaltic lavas have been investigated using the Getty-DePaolo method (Getty S. J. and DePaolo D. J. [1995] Quaternary geochronology by the U-Th-Pb method. Geochim. Cosmochim. Acta 59, 3267 3272), which allows for the resolution of small isotopic differences. Phenocryst, matrix, and whole rock analyses were made on samples from the 17 Myr-old Imnaha basalts of the Columbia River Group, a zero-age MORB from the Mid-Atlantic Ridge, and a ca. 260 kyr-old tholeiite from Mount Etna. Plagioclase feldspar phenocrysts have low-(U, Th)/Pb, and in each sample the plagioclase has significantly lower 206Pb/207Pb and 208Pb/207Pb values than whole rock, matrix, and magnetite-rich separates. The Pb isotopic contrast between plagioclase and matrix/whole rock is found in three samples with varying grain sizes (0.5 2 cm for the Imnaha basalt and MORB and <1 mm for the Etna sample) from different tectonic settings, suggesting that these results are not unique. The isotopic contrasts are only slightly smaller in magnitude than the variations exhibited by whole rock samples from the region. The Imnaha basalts also have Sr isotopic heterogeneity evident only in plagioclase phenocrysts, but the MORB and Etna lavas do not. The isotopic heterogeneities reflect magma mixing, and indicate that isotopically diverse magmas were mixed together just prior to eruption. The results reinforce indications from melt inclusion studies that magma source region isotopic heterogeneities have large amplitudes at short length scales, and that the isotopic variations imparted to the magmas are not entirely homogenized during segregation and transport processes.

  14. Coral-based history of lead and lead isotopes of the surface Indian Ocean since the mid-20th century

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Mi; Boyle, Edward A.; Suci Nurhati, Intan; Pfeiffer, Miriam; Meltzner, Aron J.; Suwargadi, Bambang

    2014-07-01

    Anthropogenic lead (Pb) from industrial activities has greatly altered the distribution of Pb in the present-day oceans, but no continuous temporal Pb evolution record is available for the Indian Ocean despite rapidly emerging industries around the region. Here, we present the coral-inferred annual history of Pb concentration and isotope ratios in the surface Indian Ocean since the mid-20th century (1945-2010). We analyzed Pb in corals from the Chagos Archipelago, western Sumatra and Strait of Singapore - which represent the central Indian Ocean via nearshore sites. Overall, coral Pb/Ca increased in the mid-1970s at all the sites. However, coral Pb isotope ratios evolve distinctively at each site, suggesting Pb contamination arises from different sources in each case. The major source of Pb in the Chagos coral appears to be India's Pb emission from leaded gasoline combustion and coal burning, whereas Pb in western Sumatra seems to be largely affected by Indonesia's gasoline Pb emission with additional Pb inputs from other sources. Pb in the Strait of Singapore has complex sources and its isotopic composition does not reflect Pb from leaded gasoline combustion. Higher 206Pb/207Pb and 208Pb/207Pb ratios found at this site may reflect the contribution of Pb from coals and ores from southern China, Indonesia, and Australia, and local Pb sources in the Strait of Singapore. It is also possible that the Pb isotope ratios of Singapore seawater were elevated through isotope exchange with natural fluvial particles considering its delta setting.

  15. Selected organochlorine pesticides and polychlorinated biphenyls in atmosphere at Ruoergai high altitude prairie in eastern edge of Qinghai-Tibet Plateau and their source identifications

    NASA Astrophysics Data System (ADS)

    Gai, Nan; Pan, Jing; Tang, Hua; Tan, Ke-Yan; Chen, Da-Zhou; Zhu, Xiao-Hua; Lu, Guo-Hui; Chen, Shu; Huang, Yi; Yang, Yong-Liang

    2014-10-01

    Compared to the low-altitude areas, high-altitude regions have low air temperature and relatively high snow precipitation. These climatological characteristics will affect the environmental behavior of persistent organic pollutants (POPs) in such a special geographical environment, leading to cold-trapping of certain POPs in these areas. Ruoergai highland prairie in the eastern edge of the Qinghai-Tibetan Plateau was selected to study the distribution characteristics of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in aerosols and gas phase samples collected in two seasons of 2011 and measured by isotope dilution-HRGC/HRMS method. OCPs and PCBs in the Ruoergai air were at low levels compared with the adjacent populated areas such as Lanzhou and Chengdu. Higher concentrations of POPs in aerosol and gas phase were observed in winter than in summer, showing the impact of monsoon on the transport of POPs to this region. Northwesterly winds in winter may transport OCPs and PCBs from industrial and agricultural areas in the northwestern China. HCB, α-HCH, and PCB 28 were the predominant compounds found in the air. Soil to air fugacity ratios show that Ruoergai soils behave as a secondary source of the relatively volatile compounds (HCHs, α-endosulfan, PCB 28 and 52) to the atmosphere during summer and behave as a sink of atmospheric DDTs due to the OC-rich soils as well as lower temperatures. Similar 206Pb/207Pb and 208Pb/207Pb ratios in Ruoergai aerosols to those of aerosols of Lanzhou and ores in Qinghai, Xinjiang, Kazakhstan, and Russia may indicate that the aerosol sources were mainly related to air mass passing over the neighboring regions and countries.

  16. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    USGS Publications Warehouse

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ202Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ202Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206Pb/207Pb and 208Pb/207Pb isotopic compositions during these periods. Data for Δ199Hg and Δ201Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ199Hg and Δ201Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger.

  17. Atmospherically deposited trace metals from bulk mineral concentrate port operations.

    PubMed

    Taylor, Mark Patrick

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection.

  18. The Contribution of Trans-Pacific Submicron Aerosols and Local Particle Nucleation Bursts to California's Air Quality as Seen from the Pacific Coast Mountain Range

    NASA Astrophysics Data System (ADS)

    Asher, E. C. C.; Christensen, J. N.; Post, A.; Faloona, I. C.

    2015-12-01

    The long-range transport of dust and anthropogenic aerosols to the Western US has received considerable attention due to the growing disparity between North American and Asian air quality. Using MODIS and space-borne LIDAR measurements some have argued that the transcontinental transport of dust from Asia, Africa, and Europe outweighs that of locally produced combustion aerosols (Yu et al. 2012). This study seeks to compare the aerosol composition, number, and size distribution of locally derived submicron aerosols (including particle nucleation events) vs. long-range transported aerosols observed at a remote mountain site near the Pacific Coast. Toward this aim, rotating drum impactor (RDI) and scanning mobility particle size (SMPS) measurements of size-segregated elemental compositions and size spectra were collected from February to November of 2012 at Chews Ridge (elevation 1450 m) in Monterey County, California. This mountaintop site experiences two main wind modes. The main mode is ohshore-directed winds from the southwest, which are most likely to bring trans-Pacific aerosols to the site; and offshore-directed, northeasterly winds that bring continental aerosols to the site from the interior of California. Elemental ratios (normalized to Al), matrix factorization, and a k-cluster analysis of these data suggest distinct crustal, combustion, and marine sources with considerable seasonal as well as short-term variability. HYSPLIT model back trajectories support the hypothesized sources of these submicron aerosols. Locally, SMPS data reveal consistent nucleation bursts and subsequent growth in the 20-60 nm range during the afternoons. A distinct but weaker diel cycle was observed in the 70 - 100 nm range, corresponding to the smallest RDI impactor stage. Finally, the Pb isotopic composition (206Pb/207Pb and 208Pb/207Pb) of aerosol samples from selected dates will be measured by MC-ICPMS to further identify aerosol origins (e.g. Ewing et al. 2010).

  19. Pb-Sr-Nd isotopes in surficial materials at the Pebble Porphyry Cu-Au-Mo Deposit, Southwestern Alaska: can the mineralizing fingerprint be detected through cover?

    USGS Publications Warehouse

    Ayuso, Robert A.; Kelley, Karen D.; Eppinger, Robert G.; Forni, Francesca

    2013-01-01

    The Cretaceous Pebble porphyry Cu-Au-Mo deposit is covered by tundra and glacigenic sediments. Pb-Sr-Nd measurements were done on sediments and soils to establish baseline conditions prior to the onset of mining operations and contribute to the development of exploration methods for concealed base metal deposits of this type. Pebble rocks have a moderate range for 206Pb/204Pb = 18.574 to 18.874, 207Pb/204Pb = 15.484 to 15.526, and 208,Pb/204Pb = 38.053 to 38.266. Mineralized granodiorite shows a modest spread in 87Sr/86Sr (0.704354–0.707621) and 143Nd/144Nd (0.512639–0.512750). Age-corrected (89 Ma) values for the granodiorite yield relatively unradiogenic Pb (e.g., 207Pb/204Pb 87Sr/86Sr, and positive values of ɛNd (1.00–4.52) that attest to a major contribution of mantle-derived source rocks. Pond sediments and soils have similar Pb isotope signatures and 87Sr/86Sr and 143Nd/144Nd values that resemble the mineralized granodiorites. Glacial events have obscured the recognition of isotope signatures of mineralized rocks in the sediments and soils. Baseline radiogenic isotope compositions, prior to the onset of mining operations, reflect natural erosion, transport and deposition of heterogeneous till sheets that included debris from barren rocks, mineralized granodiorite and sulfides from the Pebble deposit, and other country rocks that pre- and postdate the mineralization events. Isotopic variations suggest that natural weathering of the deposit is generally reflected in these surficial materials. The isotope data provide geochemical constraints to glimpse through the extensive cover and together with other geochemical observations provide a vector to concealed mineralized rocks genetically linked with the Pebble deposit.

  20. Radiogenic Isotopes As Paleoceanographic Tracers in Deep-Sea Corals: Advances in TIMS Measurements of Pb Isotopes and Application to Southern Ocean Corals

    NASA Astrophysics Data System (ADS)

    Wilson, D. J.; van de Flierdt, T.; Bridgestock, L. J.; Paul, M.; Rehkamper, M.; Robinson, L. F.; Adkins, J. F.

    2014-12-01

    Deep-sea corals have emerged as a valuable archive of deep ocean paleoceanographic change, with uranium-series dating providing absolute ages and the potential for centennial resolution. In combination with measurements of radiocarbon, neodymium isotopes and clumped isotopes, this archive has recently been exploited to reconstruct changes in ventilation, water mass sourcing and temperature in relation to millennial climate change. Lead (Pb) isotopes in both corals and seawater have also been used to track anthropogenic inputs through space and time and to trace transport pathways within the oceans. Better understanding of the oceanic Pb cycle is emerging from the GEOTRACES programme. However, while Pb isotopes have been widely used in environmental studies, their full potential as a (pre-anthropogenic) paleoceanographic tracer remains to be exploited. In deep-sea corals, challenges exist from low Pb concentrations in aragonite in comparison to secondary coatings, the potential for contamination, and the efficient elemental separation required for measurement by thermal ionisation mass spectrometry (TIMS). Here we discuss progress in measuring Pb isotopes in coral aragonite using a 207Pb-204Pb double spike on a ThermoFinnigan Triton TIMS. For a 2 ng NIST-981 Pb standard, the long term reproducibility (using 1011 Ω resistors) is ~1000 ppm (2 s.d.) on 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios. We now show that using a new 1012 Ω resistor to measure the small 204Pb beam improves the internal precision on these ratios from ~500 ppm (2 s.e.) to ~250 ppm (2 s.e.) and we envisage a potential improvement in the long term reproducibility as a consequence. We further assess the internal precision and external reproducibility of our method using a BCR-2 rock standard and an in-house coral standard. Preliminary evidence on the application of this method to natural samples is derived from cleaning experiments and replication tests on deep-sea corals from the Southern

  1. An ultra-clean technique for accurately analysing Pb isotopes and heavy metals at high spatial resolution in ice cores with sub-pg g(-1) Pb concentrations.

    PubMed

    Burn, Laurie J; Rosman, Kevin J R; Candelone, Jean-Pierre; Vallelonga, Paul; Burton, Graeme R; Smith, Andrew M; Morgan, Vin I; Barbante, Carlo; Hong, Sungmin; Boutron, Claude F

    2009-02-23

    Measurements of Pb isotope ratios in ice containing sub-pg g(-1) concentrations are easily compromised by contamination, particularly where limited sample is available. Improved techniques are essential if Antarctic ice cores are to be analysed with sufficient spatial resolution to reveal seasonal variations due to climate. This was achieved here by using stainless steel chisels and saws and strict protocols in an ultra-clean cold room to decontaminate and section ice cores. Artificial ice cores, prepared from high purity water were used to develop and refine the procedures and quantify blanks. Ba and In, two other important elements present at pg g(-1) and fg g(-1) concentrations in Polar ice, were also measured. The final blank amounted to 0.2+/-0.2 pg of Pb with (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of 1.16+/-0.12 and 2.35+/-0.16, respectively, 1.5+/-0.4 pg of Ba and 0.6+/-2.0 fg of In, most of which probably originates from abrasion of the steel saws by the ice. The procedure was demonstrated on a Holocene Antarctic ice core section and was shown to contribute blanks of only approximately 5%, approximately 14% and approximately 0.8% to monthly resolved samples with respective Pb, Ba and In concentrations of 0.12 pg g(-1), 0.3 pg g(-1) and 2.3 fg g(-1). Uncertainties in the Pb isotopic ratio measurements were degraded by only approximately 0.2%.

  2. Chemical and isotopic studies of granitic Archean rocks, Owl Creek Mountains, Wyoming: Uranium-thorium-lead systematics of an Archean granite from the Owl Creek Mountains, Wyoming

    SciTech Connect

    Stuckless, J.S.; Nkomo, I.T.; Butt, K.A.

    1986-01-01

    Isotopic analyses of apparently unaltered whole-rock samples of a granite from the Owl Creek Mountains, Wyo., yield a lead-lead isochron age of 2730 {plus minus} 35 Ma, which is somewhat older than the age obtained by the rubidium-strontium whole-rock method. Thorium-lead data for the same samples deviate markedly from an isochronal relation; however, calculated initial {sup 208}Pb/{sup 204}Pb ratios correlate with whole-rock {delta}{sup 18}O values and lead to the conclusion that the {sup 232}Th-{sup 208}Pb data are not colinear because of an originally heterogeneous granitic magma. Relationships in the {sup 207}Pb/{sup 235}U-{sup 206}Pb/{sup 238}U system show that uranium was mobilized during early Laramide time or shortly before, such that most surface and shallow drill-core samples lost 60-80 percent of their uranium, and some fractured, deeper drill-core samples gained from 50 to 10,000 percent uranium. Fission-track maps show that much uranium is located along edges and cleavages of biotite and magnetic where it is readily accessible to oxidizing ground water. Furthermore, qualitative comparisons of uranium distribution in samples with excess radiogenic lead and in samples with approximately equilibrium amounts of uranium and lead suggest that the latter contain more uranium in these readily accessible sites. Unlike other granites that have uranium distributions and isotopic systematics similar to those observed in this study, the granite of the Owl Creek Mountains is not associated with economic uranium deposits.

  3. Investigation of Lead Target Nuclei Used on Accelerator-Driven Systems for Tritium Production

    NASA Astrophysics Data System (ADS)

    Tel, E.; Aydin, A.

    2012-02-01

    High-current proton accelerators are being researched at Los Alamos National Laboratory and other laboratories for accelerator production of tritium, transmuting long-lived radioactive waste into shorter-lived products, converting excess plutonium, and producing energy. These technologies make use of spallation neutrons produced in ( p,xn) and ( n,xn) nuclear reactions on high-Z targets. Through ( p,xn) and ( n,xn) nuclear reactions, neutrons are produced and are moderated by heavy water. These moderated neutrons are subsequently captured on 3He to produce tritium via the ( n,p) reaction. Tritium self-sufficiency must be maintained for a commercial fusion power plant. Rubbia succeeded in a proposal of a full scale demonstration plant of the Energy Amplifier. This plant is to be known the accelerator-driven system (ADS). The ADS can be used for production of neutrons in spallation neutron source and they can act as an intense neutron source in accelerator-driven subcritical reactors, capable of incinerating nuclear waste and of producing energy. Thorium and Uranium are nuclear fuels and Lead, Bismuth, Tungsten are the target nuclei in these reactor systems. The spallation targets can be Pb, Bi, W, etc. isotopes and these target material can be liquid or solid. Naturally Lead includes the 204Pb (%1.42), 206Pb (%24.1), 207Pb (%22.1) and 208Pb (%52.3) isotopes. The design of ADS systems and also a fusion-fission hybrid reactor systems require the knowledge of a wide range of better data. In this study, by using Hartree-Fock method with an effective nucleon-nucleon Skyrme interactions rms nuclear charge radii, rms nuclear mass radii, rms nuclear proton, neutron radii and neutron skin thickness were calculated for the 204, 206, 208Pb isotopes . The calculated results have been compared with those of the compiled experimental and theoretical values of other studies.

  4. Childhood lead exposure in an industrial town in China: coupling stable isotope ratios with bioaccessible lead.

    PubMed

    Li, Hong-Bo; Chen, Kai; Juhasz, Albert L; Huang, Lei; Ma, Lena Q

    2015-04-21

    Fingerprinting based on stable isotopes of lead (Pb) in blood and environmental media helps to identify Pb exposure pathways in children. However, previous studies used stable isotopes of total Pb in media. In this study, a wire rope production town in China (Zhuhang) was selected for investigating the effectiveness of using isotope ratios in bioaccessible Pb to identify childhood Pb exposure pathways. Blood Pb levels of 115 children in Zhuhang were 1.7-20.4 μg dL(-1), averaging 6.1 ± 3.2 μg dL(-1) (mean ± standard deviation), and were ∼1.6 times the national average in China (3.9 ± 1.8 μg dL(-1)). Among different environmental media (housedust, soil, PM10, vegetables, rice, and drinking water), housedust (695 ± 495 mg kg(-1)) and vegetables [0.36 ± 0.40 mg (kg of fresh weight)(-1)] contained elevated Pb concentrations. The isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) of total Pb were the highest in housedust (0.8587 ± 0.0039 and 2.1049 ± 0.0087) but lower than blood Pb ratios (0.8634 ± 0.0027 and 2.1244 ± 0.0061). When using bioaccessible Pb in housedust (0.8639 ± 0.0018 and 2.1171 ± 0.0036), the isotope ratios overlapped with blood Pb ratios, suggesting that incidental ingestion of housedust was the predominant contributor to children's blood Pb. Coupling the stable isotope technique with bioaccessible Pb is more reliable for identifying Pb exposure pathways than total Pb determinations.

  5. Character of the pre-Mesozoic basement along the edge of the western US craton: Pb isotopic evidence from Mesozoic plutonism

    SciTech Connect

    Wooden, J.L.; Kistler, R.W.; Robinson, A.; Tosdal, R.M. ); Wright, J.E. . Dept. of Geology and Geophysics)

    1993-04-01

    The pre-Mesozoic cratonic crust of the western US was a composite of provinces composed mostly of Archean and Early Proterozoic rocks that had been truncated by Late Proterozoic rifting and had some new Paleozoic crust added along the western edge. Mesozoic and younger geologic events greatly obscured this pre-Mesozoic basement along the craton edge. However, the Pb isotopic signatures of Mesozoic plutons provide significant clues to the character of the crust in which they formed or were emplaced because of a strong contrast in Pb concentration between low-Pb, mantle-derived melts and Pb-rich crust. Thus, magmas whether derived from the crust or the mantle with subsequent crustal interaction, will likely have Pb isotopic compositions that reflect those of the crust. In the western US the Pb isotopic compositions of Mesozoic plutonic rocks have strong regional characteristics. Within the Early Proterozoic Mojave crustal province, Mesozoic plutonic rocks have a large range of 206Pb/204Pb ratios that plot above the crustal average, relatively high 207Pb/204Pb ratios that suggest an Archean contribution, and Pb and Sr isotopic compositions that are not correlated and that do not distinguish age groups. At the southern and western edge of this province where some 1.1 Ga rocks are exposed, 208Pb/204Pb ratios lie along the average crust model curve. These data suggest that any individual pluton provides a composite Pb isotopic composition for a discrete vertical section of the crust. Pb isotopic compositions of plutons in the Sierra Nevada and Great Basin are very different from those described above with 206Pb/204Pb ratios starting at 18.6, well-correlated Pb isotopic trends starting below the crustal model but extending to values that require input from the very radiogenic Wyoming province Archean crust, and good correlations between Pb and (1) Sr isotopic compositions and (2) W-E geographic position.

  6. Some Pb and Sr isotopic measurements on eclogites from the Roberts Victor mine, South Africa

    USGS Publications Warehouse

    Manton, W.I.; Tatsumoto, M.

    1971-01-01

    Five nodules of eclogite, one nodule of garnet peridotite and one sample of kimberlite from the Roberts Victor mine were analyzed for concentrations of U, Th, Pb, Rb and Sr and isotopic compositions of Pb and Sr. In the eclogites, U content ranges from 0.09 to 0.26 ppm, Th from 0.35 to 1.1 ppm, Pb from 0.79 to 5.5 ppm, Rb from 2.1 to 28 ppm and Sr from 133 to 346 ppm; 206Pb/204Pb ratios range from 14.8 to 18.5, 207Pb/204Pb from 14.9 to 15.7, 208Pb/204Pb from 35.2 to 38.5. The garnet peridotite contains 0.22 ppm U, 0.97 ppm Th, 1.05 ppm Pb, 6.9 ppm Rb and 108 ppm Sr and the kimberlite contains 2.5 ppm U, 30 ppm Th, 37 ppm Pb, 113 ppm Rb and 2040 ppm Sr. The lead in the eclogites has two components, a lead pyroextractable at 1100-1200?? and a non-pyroextractable residual lead. In three of the eclogites, which are to some extent altered, a proportion of the pyroextractable lead may be contaminating lead from the kimberlite, but an altered kyanite eclogite does not appear to be contaminated by this same kimberlite. The pyroextractable lead from a less altered eclogite contains a much larger proportion of 206Pb. Compositions calculated for the residual leads vary greatly. In many of the pyroextraction runs the primary eclogitic phases disappeared and the new phases plagioclase, clinopyroxene and a magnetic iron compound were formed. Why part of the lead should have been retained by these new phases is not understood. ?? 1971.

  7. Accumulation of atmospheric radionuclides and heavy metals in cryoconite holes on an Arctic glacier.

    PubMed

    Łokas, Edyta; Zaborska, Agata; Kolicka, Małgorzata; Różycki, Michał; Zawierucha, Krzysztof

    2016-10-01

    Surface of glaciers is covered by mineral and organic dust, together with microorganisms forming cryoconite granules. Despite fact that glaciers and ice sheets constitute significance part of land surface, reservoir of freshwater, and sites of high biological production, the knowledge on the cryoconite granules still remain unsatisfactory. This study presents information on radionuclide and heavy metal contents in cryoconites. Cryoconites collected from the Hans Glacier in SW Spitsbergen reveal high activity concentrations of anthropogenic ((238,239,240)Pu, (137)Cs, (90)Sr) and natural ((210)Pb) radionuclides. The (238)Pu/(239+240)Pu activity ratios in these cryoconites significantly exceed the mean global fallout ratio (0.025). The (238)Pu/(239+240)Pu ranged from 0.064 to 0.118. The (239+240)Pu/(137)Cs varied from 0.011 ± 0.003 to 0.030 ± 0.007. Such activity ratios as observed in these cryoconites were significantly higher than the values characterizing global fallout, pointing to possible contributions of these radionuclides from other sources. Heavy metals (Pb, Cd, Cu, Zn, Fe, and Mn) in cryoconites exceed both UCC concentrations and local rocks' concentrations, particularly for cadmium. The concentration ratios of stable lead isotopes ((206)Pb/(207)Pb, (208)Pb/(206)Pb) were determined to discriminate between the natural and anthropogenic sources of Pb in cryoconites and to confirm the strong anthropogenic contribution to heavy metal deposition in the Arctic. In investigated cryoconite holes, two groups of invertebrates, both extremophiles, Tardigrada and Rotifera were detected. Our study indicate that cryoconites are aggregates of mineral and organic substances on surfaces of glaciers are able to accumulate large amounts of airborne pollutants bound to extracellular polymeric substances secreted by microorganisms.

  8. The isotopic composition of lead in potassium feldspars from some 1.0-b.y. old North American igneous rocks

    USGS Publications Warehouse

    Zartman, R.E.; Wasserburg, G.J.

    1969-01-01

    The isotopic composition of lead and the uranium, thorium and lead concentrations in potassium feldspars are determined for more than 30 1.0-b.y. old North American igneous rocks. Samples representing a broad spectrum in petrographic type and mode of occurrence were chosen; an effort was made to include only rocks having well-documented ages from 950 to 1140 m.y. and showing minimal evidence of subsequent metamorphism. Most samples, including those from extensive terranes of contemporaneous age, have limited lead isotope variations ( Pb206 Pb204 = 16.74-17.38; Pb207 Pb204 = 15.39-15.59; Pb208 Pb204 = 36.38-37.10), which yield model ages close to the radiometric ages. Granite, pegmatite, and rhyolite from within the Grenville province of Canada and age-equivalent rocks of New York, Virginia, Texas, and Colorado and granophyric units associated with the Duluth Gabbro Complex of Minnesota are among the materials yielding this main isotopic spectrum. Several samples were encountered which had isotopic compositions very different from the above group. Lead showing a marked deficiency in radiogenic isotopes was found in two granitic bodies associated with older Labrador Trough rocks from Quebec, in a rapakivi granite from southern Nevada, and in a small granite stock from Mellen, Wisconsin. These occurrences all involve small intrusions of granite which lie near considerably older areas of basement rock. Model ages calculated from the Pb206 Pb204 ratio are older than the age of the intrusions and approach the age of the host basement rock. Several possible interpretations are offered to explain the isotopic behavior encountered in this study. In particular, a "vertically differentiated crust" model is proposed which will account for both the main spectrum and the anomalous lead. The significance of lead isotopic studies in understanding crustal structure in continental regions is discussed. ?? 1969.

  9. From olivine nephelinite, basanite and basalt to peralkaline trachyphonolite and comendite in the Ankaratra volcanic complex, Madagascar: 40Ar/39Ar ages, phase compositions and bulk-rock geochemical and isotopic evolution

    NASA Astrophysics Data System (ADS)

    Cucciniello, Ciro; Melluso, Leone; le Roex, Anton P.; Jourdan, Fred; Morra, Vincenzo; de'Gennaro, Roberto; Grifa, Celestino

    2017-03-01

    The Ankaratra volcanic field covers an area of 3800 km2 in central Madagascar and comprises of lava flows, lava domes, scoria cones, tuff rings and maars emplaced at different ages (Miocene to Recent). The volcanic products include ultramafic-mafic (olivine-leucite nephelinite, basanite, alkali basalt, hawaiite and tholeiitic basalt), intermediate (mugearite and benmoreite) and felsic rocks (trachyphonolite, quartz trachyte and rhyolite), the latter often peralkaline. The 40Ar/39Ar determinations for mafic lavas yield ages of 17.45 ± 0.12 Ma, 16.63 ± 0.08 Ma and 8.62 ± 0.09 Ma, indicating a prolonged magmatic activity. The mineralogical and geochemical variations suggest that the magmatic evolution of the alkali basalt-hawaiite-mugearite-benmoreite-trachyte series can be accounted for by removal of olivine, feldspars, clinopyroxene, Fe-Ti oxides and accessory phases, producing residual trachytic and trachyphonolitic compositions mineralogically very similar to those of other volcanic areas and tectonic settings. The Ankaratra olivine leucite nephelinites, basanites and tholeiitic basalts do not seem to be associated with significant amounts of evolved comagmatic rocks. The 87Sr/86Sr (0.70504-0.71012), 143Nd/144Nd (0.51259-0.51244) and 206Pb/204Pb (17.705-18.563) isotopic ratios of trachytes and comendite are consistent with open-system processes. However, other trachyphonolites have 143Nd/144Nd (0.51280), 206Pb/204Pb (18.648), 207Pb/204Pb (15.582) and 208Pb/204Pb (38.795) similar to those of mafic rocks, suggesting differentiation processes without appreciable interaction with crustal materials. The Ankaratra volcanism is to be directly linked to a broadly E-W-trending intracontinental extension. A large-scale thermal anomaly, associated with an anomalously hot source region, is not required to explain the Cenozoic magmatism of Madagascar.

  10. Isotopes and Trace Elements as Natal Origin Markers of Helicoverpa armigera – An Experimental Model for Biosecurity Pests

    PubMed Central

    Holder, Peter W.; Armstrong, Karen; Van Hale, Robert; Millet, Marc-Alban; Frew, Russell; Clough, Timothy J.; Baker, Joel A.

    2014-01-01

    Protecting a nation's primary production sector and natural estate is heavily dependent on the ability to determine the risk presented by incursions of exotic insect species. Identifying the geographic origin of such biosecurity breaches can be crucial in determining this risk and directing the appropriate operational responses and eradication campaigns, as well as ascertaining incursion pathways. Reading natural abundance biogeochemical markers using mass spectrometry is a powerful tool for tracing ecological pathways as well as provenance determination of commercial products and items of forensic interest. However, application of these methods to trace insects has been underutilised to date and our understanding in this field is still in a phase of basic development. In addition, biogeochemical markers have never been considered in the atypical situation of a biosecurity incursion, where sample sizes are often small, and of unknown geographic origin and plant host. These constraints effectively confound the interpretation of the one or two isotope geo-location markers systems that are currently used, which are therefore unlikely to achieve the level of provenance resolution required in biosecurity interceptions. Here, a novel approach is taken to evaluate the potential for provenance resolution of insect samples through multiple biogeochemical markers. The international pest, Helicoverpa armigera, has been used as a model species to assess the validity of using naturally occurring δ2H, 87Sr/86Sr, 207Pb/206Pb and 208Pb/206Pb isotope ratios and trace element concentration signatures from single moth specimens for regional assignment to natal origin. None of the biogeochemical markers selected were individually able to separate moths from the different experimental regions (150–3000 km apart). Conversely, using multivariate analysis, the region of origin was correctly identified for approximately 75% of individual H. armigera samples. The geographic resolution

  11. Impact of urbanization on sediment chemistry in small-scale watersheds, southeast Virginia.

    NASA Astrophysics Data System (ADS)

    Evans, M. J.; Packard, H.

    2007-12-01

    The state of Virginia contains only two natural bodies of water with the rest being comprised of mill ponds, farm ponds and impoundment lakes. These man made water bodies are ubiquitous along the eastern seaboard. Southeast Virginia (Williamsburg, Jamestown and surrounding counties) was the locus of early European settlement and many of the local ponds date back to the early colonial period. As such, the sediment record in these ponds provides a unique historical record of the impact human activity can have on small watersheds. Two small man-made ponds (Lake Matoaka and Jolly Pond) were studied. Both ponds lie within the James River basin, a major feeder to the Chesapeake Bay. Both drainage basins cover ~600 ha but differ significantly in the level of development. Lake Matoaka was originally dammed ca. 1720. The Matoaka drainage is currently experiencing rapid development (~22% high population residential/commercial) and includes the College of William & Mary's campus. Jolly Pond and the two dams that created it first appear on maps dating back to 1863. The Jolly Pond basin is largely dominated by forests and agricultural land. Sediment cores were taken from both ponds using a Russian peat corer, Matoaka to 1.5m depth and Jolly Pond to 0.9m dpeth. Sediment splits were analyzed for total exchangeable lead concentration and lead isotopes (207Pb/206Pb & 208Pb/206Pb), as well total carbon and nitrogen. Carbon/Nitrogen ratios were used to indicate changes in water level and dam height increases. Lead concentrations in both cores show a peak associated with leaded gasoline use. [Pb] in Matoaka are significant (~320 ppm) and show a clear anthropogenic isotopic signature. Jolly Pond [Pb] are surprisingly low and are close to background values. These data indicate that even minimal development has significant impact on sediment chemistry. Likely lead sources for Lake Matoaka include road and building runoff and lead aerosols.

  12. Lead isotopes and trace metals in dust at Yucca Mountain

    USGS Publications Warehouse

    Kwak, Loretta; Neymark, Leonid A.; Peterman, Zell E.

    2008-01-01

    Lead (Pb)-isotope compositions and trace-metal concentrations were determined for samples of dust collected from underground and surface locations at and near the proposed radioactive waste repository at Yucca Mountain, Nevada. Rare earth element concentrations in the dust samples from the underground tunnels are similar to those in wholerock samples of the repository host rocks (Miocene Tiva Canyon Tuff and Topopah Spring Tuff), supporting interpretation that the subsurface dust is mainly composed of rock comminuted during tunnel construction. Other trace metals (arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead, antimony, thallium, and zinc) are variably enriched in the subsurface dust samples relative to the average concentrations in the host rocks. Average concentrations of arsenic and lead in dust samples, high concentrations of which can cause corrosion of waste canisters, have enrichment factors from 1.2 to 1.6 and are insignificant relative to the range of concentrations for these metals observed in the host rock samples. Most dust samples from surface sites also are enriched in many of these trace metals relative to average repository host rocks. At least some of these enrichments may be artifacts of sampling. Plotted on a 208Pb/206Pb-207Pb/206Pb graph, Pb-isotope compositions of dust samples from underground sites form a mixing line extending from host-rock Pb-isotope compositions towards compositions of many of the dust samples from surface sites; however, combined Pb concentration and isotope data indicate the presence of a Pbenriched component in the subsurface dust that is not derived from host rock or surface dust and may derive from anthropogenic materials introduced into the underground environment.

  13. Tracing dust transport from Middle-East over Delhi in March 2012 using metal and lead isotope composition

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Aggarwal, S. G.; Malherbe, J.; Barre, J. P. G.; Berail, S.; Gupta, P. K.; Donard, O. F. X.

    2016-05-01

    A severe dust-storm which was originated in Middle-East crossed over Delhi during March 20-22, 2012. We have collected these dust-storm (DS) aerosol samples, and analyzed them for selected metals (As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, Se, Sn, Sr, V and Zn) together with after dust-storm (ADS) and winter (WS) samples. High aerosol mass loadings were observed in DS samples (1097-1965 μg/m3). On the contrary, metals derived prominently from the anthropogenic sources were found lower in concentration compared to that of ADS and WS aerosols. We observed significantly high concentrations of Ni and V (which are abundantly found in crude oils of Middle-East origin) in the DS samples than that of ADS and WS samples. Also enrichment factor (EF) of these metals with respect to Fe shows no significant enrichment (<10). Fe (and Sr) concentrations were also 3-5 fold higher in DS samples compared to ADS and WS. These results suggest that Ni and V can be used as tracers for dust aerosols transported from Middle-East region. Lead isotope signatures can tell about the variation in the sources of urban aerosols. Therefore Pb isotope analyses of these samples were performed using MC-ICP-MS. The isotope ratios, 208Pb/206Pb is determined to be (mean ± sd) 2.1315 ± 0.0018, 2.1370 ± 0.0022 and 2.1389 ± 0.0016, whereas 206Pb/207Pb is 1.1311 ± 0.0022, 1.1244 ± 0.0017 and 1.1233 ± 0.0016 in DS, ADS and WS aerosols, respectively. There is a clear distinction in Pb isotope composition between DS and urban (ADS and WS) aerosols. Further, these results suggest that in urban aerosols, Pb is less radiogenic in nature compared to that of in transported dust aerosols collected in New Delhi.

  14. An atmospheric lead source-areas apportionment study in Europe

    NASA Astrophysics Data System (ADS)

    Flament, P.; Deboudt, K.; Bertho, M.-L.; Véron, A.; Puskaric, E.

    2003-05-01

    Atmospheric particulate matter samples, for which the origin of aerosols was unambiguousty determined, has been collected in the Eastern Channel (Northem France). Associated lead concentrations are higher by a factor of about 7, when air masses are runnig from continental Europe, by comparison with marine air masses. We statistically evidence that air masses originating from continental Europe exhibit a more radiogenic composition (1.134<^{206}Pb/^{207}Pb<1.172) than air masses coming from British Islands (1.106<^{206}Pb/^{207}Pb<1.1243. Generally, lead isotopic compositions in aerosols are dearly distinct from the gasoline signatures in European countries, strongly suggesting that automotive lead is no more the major component of this metal in the air. Gasoline and industrial isotopic signatures could explain the origin of lead in our aerosol samples. A source apportionment based upon ^{206}Pb/^{207}Pb ratios suggests that thé difference between British (^{206}Pb/^{207}Pb = 1.122 ± 0.038) and continental (^{206}Pb/^{207}Pb = 1.155 ± 0.022) signatures may be explained by differenees iro the petrol leard content of aerosols (23 to 62% in Great Britain versus 10 to 36% in continental Europe).

  15. Lead in the Getchell-Turquoise ridge Carlin-type gold deposits from the perspective of potential igneous and sedimentary rock sources in Northern Nevada: Implications for fluid and metal sources

    USGS Publications Warehouse

    Tosdal, R.M.; Cline, J.S.; Fanning, C.M.; Wooden, J.L.

    2003-01-01

    Lead isotope compositions of bulk mineral samples (fluorite, orpiment, and realgar) determined using conventional techniques and of ore-stage arsenian pyrite using the Sensitive High Resolution Ion-Microprobe (SHRIMP) in the Getchell and Turquoise Ridge Carlin-type gold deposits (Osgood Mountains) require contribution from two different Pb sources. One Pb source dominates the ore stage. It has a limited Pb isotope range characterized by 208Pb/206Pb values of 2.000 to 2.005 and 207Pb/206Pb values of 0.8031 to 0.8075, as recorded by 10-??m-diameter spot SHRIMP analyses of ore-stage arsenian pyrite. These values approximately correspond to 206Pb/204Pb of 19.3 to 19.6, 207Pb/204Pb of 15.65 to 15.75, and 208Pb/204Pb of 39.2 to 39.5. This Pb source is isotopically similar to that in average Neoproterozoic and Cambrian elastic rocks but not to any potential magmatic sources. Whether those clastic rocks provided Pb to the ore fluid cannot be unequivocally proven because their Pb isotope compositions over the same range as in ore-stage arsenian pyrite are similar to those of Ordovician to Devonian siliciclastic and calcareous rocks. The Pb source in the calcareous rocks most likely is largely detrital minerals, since that detritus was derived from the same sources as the detritus in the Neoproterozoic and Cambrian clastic rocks. The second Pb source is characterized by a large range of 206Pb/204Pb values (18-34) with a limited range of 208Pb/204Pb values (38.1-39.5), indicating low but variable Th/U and high and variable U/Pb values. The second Pb source dominates late and postore-stage minerals but is also found in preore sulfide minerals. These Pb isotope characteristics typify Ordovician to Devonian siliciclastic and calcareous rocks around the Carlin trend in northeast Nevada. Petrologically similar rocks host the Getchell and Turquoise Ridge deposits. Lead from the second source was either contributed from the host sedimentary rock sequences or brought into the

  16. Bioavailability and Sources of Lead in the Terrestrial Environment of Egypt

    NASA Astrophysics Data System (ADS)

    Marzouk, Ezzat; Shetaya, Waleed; Elkassas, Mohamed; Mohamed, Elham; Bailey, Elizabeth; Young, Scott

    2016-04-01

    . Isotopic ratios (206Pb/207Pb and 208Pb/207Pb) fell on a mixing line between end-members attributed to petrol and regional geogenic Pb sources and clearly showed a distinction between Pb from geogenic and anthropogenic sources (mainly petrol-derived Pb). In contaminated locations, there was clear evidence that petrol-derived Pb, in average, remained considerably more labile than Pb from the soil parent material. However, in all samples, both petrol-derived and geogenic Pb contributed to the labile fraction depending on soil conditions.

  17. Pb, Nd, and Sr isotopic evidence for a multicomponent source for rocks of Cook-Austral Islands and heterogeneities of mantle plumes

    USGS Publications Warehouse

    Nakamura, Y.; Tatsumoto, M.

    1988-01-01

    Sr, Nd, and Pb isotopic compositions were measured in alkaline volcanic rocks (alkali basalt, ankaramite, nephelinite, phonolite, and trachyte) from the South Cook Islands (Aitutaki, Mauke, Rarotonga, Atiu, and Mangaia) and the Austral Islands (Rimatara and Rurutu). The results show that the Cook-Austral rocks have an extremely wide range in isotopic compositions of Pb: 206Pb 204Pb from 18.25 to 21.76, 207pb 204pb from 15.48 to 15.83, and sol208pb 204Pb from 38.37 to 40.62, whereas isotopic compositions of Sr and Nd are less variable. Isotopically, Mangaia, Rimatara, and Rurutu form one group (Mangaia group), which shows extremely radiogenic Pb isotopic compositions but near-MORB (mid-oceanic ridge basalts) values for Sr and Nd isotopic ratios. In contrast, samples from Aitutaki, Rarotonga, Mauke, and Atiu (Aitutaki group) have high 207Pb 204Pb and 208Pb 204Pb and moderately high 87Sr 86Sr (Dupal anomaly). The Aitutaki group could have been derived from heterogeneous mantle plumes, which rose from the enriched deep mantle (the almost primitive lower mantle or recycled continental and oceanic slabs). On the other hand, the Mangaia component could have been derived from the depleted upper mantle which may have been metasomatized with a CO2-rich fluid, as indicated by the near-MORB values of Sr and Nd isotopes. Although Pb isotopic data of the two groups cannot be distinguished from each other statistically, the end components of the Pb-Pb system do not match with those of the Nd-Sr system. Thus, the data must be explained by a multi-, at least three, component mixing model: the mantle plumes (Dupal component and a recycled oceanic slab), metasomatized upper mantle, and lithosphere. The K-Ar ages and isotopic characteristics of the Cook-Austral rocks indicate that if one mantle plume rises from the deep mantle in this region, it has separated into at least two segments on the way to the surface. ?? 1988.

  18. Pb, Nd, and Sr isotopic evidence for a multicomponent source for rocks of Cook-Austral Islands and heterogeneities of mantle plumes

    SciTech Connect

    Nakamura, Yoichi; Tatsumoto, Mitsunobu )

    1988-12-01

    Sr, Nd, and Pb isotopic compositions were measured in alkane volcanic rocks from the South Cook Islands and the Austral Islands. The results show that the Cook-Austral rocks have an extremely wide range in isotopic compositions of Pb: {sup 206}Pb/{sup 204}Pb from 18.25 to 21.76, {sup 207}Pb/{sup 204}Pb from 15.48 to 15.83, and {sup 208}Pb/{sup 204}Pb from 38.37 to 40.62, whereas isotopic compositions of Sr and Nd are less variable. Isotopically, Mangaia, Rimatara, and Rurutu form one group, which shows extremely ratiogenic Pb isotopic compositions but near-MORB (mid-ocean ridge basalts) values for Sr and Nd isotopic ratios. In contrast, samples from Aitutaki, Rarotonga, Mauke, and Atiu (Aitutaki group) have high {sup 207}Pb/{sup 204}Pb and {sup 208}Pb/{sup 204}Pb and moderately high {sup 87}Sr/{sup 86}Sr (Dupal anomaly). The Aitutaki group could have been derived from heterogeneous mantle plumes, which rose from the enriched deep mantle (the almost primitive lower mantle or recycled continental and oceanic slabs). On the other hand, the Mangaia component could have been derived from the depleted upper mantle which may have been metasomatized with a Co{sub 2}-rich fluid, as indicated by the near-MORB values of Sr and Nd isotopes. Although Pb isotopic data of the two groups cannot be distinguished from each other statistically, the end components of the Pb-Pb system do not match with those of the Nd-Sr system. Thus, the data must be explained by a multi-, at least three, component mixing model: the mantle plumes, metasomatized upper mantle, and lithosphere. The K-Ar ages and isotopic characteristics of the Cook-Austral rocks indicate that if one mantle plume rises from the deep mantle in this region, it has separated into at least two segments on the way to the surface.

  19. Stable lead isotopic analyses of historic and contemporary lead contamination of San Francisco Bay estuary

    USGS Publications Warehouse

    Ritson, P.I.; Bouse, R.M.; Flegal, A.R.; Luoma, S.N.

    1999-01-01

    Variations in stable lead isotopic composition (240Pb, 206Pb, 207Pb, 208Pb) in three sediment cores from the San Francisco Bay estuary document temporal changes in sources of lead during the past two centuries. Sediment, with lead from natural geologic sources, and relatively homogeneous lead isotopic compositions are overlain by sediments whose isotopic compositions indicate change in the sources of lead associated with anthropogenic modification of the estuary. The first perturbations of lead isotopic composition in the cores occur in the late 1800s concordant with the beginning of industrialization around the estuary. Large isotopic shifts, toward lower 206Pb/207Pb, occur after the turn of the century in both Richardson and San Pablo Bays. A similar relationship among lead isotopic compositions and lead concentrations in both Bays suggest contamination from the same source (a lead smelter). The uppermost sediments (post 1980) of all cores also have a relatively homogenous lead isotopic composition distinct from pre-anthropogenic and recent aerosol signatures. Lead isotopic compositions of leachates from fourteen surface sediments and five marsh samples from the estuary were also analyzed. These analyses suggest that the lead isotopic signature identified in the upper horizons of the cores is spatially homogeneous among recently deposited sediments throughout the estuary. Current aerosol lead isotopic compositions [Smith, D.R., Niemeyer, S., Flegal, A.R., 1992. Lead sources to California sea otters: industrial inputs circumvent natural lead biodepletion mechanisms. Environmental Research 57, 163-175] are distinct from the isotopic compositions of the surface sediments, suggesting that the major source of lead is cycling of historically contaminated sediments back through the water column. Both the upper core sediments and surface sediments apparently derive their lead predominantly from sources internal to the estuary. These results support the idea that

  20. Lead isotopic compositions of common arsenical pesticides used in New England

    USGS Publications Warehouse

    Ayuso, Robert; Foley, Nora; Robinson, Gilpin; Wandless, Gregory; Dillingham, Jeremy

    2004-01-01

    . The new data characterize these anthropogenic sources. The data show that the arsenical pesticides have similar compositions: 208Pb/207Pb = 2.3839-2.4721, 206Pb/207Pb = 1.1035-1.2010, and 206Pb/204Pb = 17.070-18.759 and, more importantly, that the pesticides overlap the composition of the stream sediments that represent the areas with the most extensive agricultural use. Copper acetoarsenite (Paris green), arsenic oxide, methyl arsonic acid, methane arsonic acid, and arsanilic acid were also analyzed and have lead isotope compositions that range widely. An important source of arsenic and metals to most of the stream sediment samples in New England appears to be weathering products from rocks and industrial lead, but the extensive use of arsenical pesticides and herbicides up to about the 1960s can also be a significant anthropogenic source in agricultural regions.

  1. Oceanic Pb-isotopic sources of proterozoic and paleozoic volcanogenic massive sulfide deposits on Prince of Wales Island and vicinity, southeastern Alaska

    USGS Publications Warehouse

    Ayuso, Robert A.; Karl, Susan M.; Slack, John F.; Haeussler, Peter J.; Bittenbender, Peter E.; Wandless, Gregory A.; Colvin, Anna

    2005-01-01

    Volcanogenic massive sulfide (VMS) deposits on Prince of Wales Island and vicinity in southeastern Alaska are associated with Late Proterozoic through Cambrian volcanosedimentary rocks of the Wales Group and with Ordovician through Early Silurian felsic volcanic rocks of the Moira Sound unit (new informal name). The massive sulfide deposits in the Wales Group include the Big Harbor, Copper City, Corbin, Keete Inlet, Khayyam, Ruby Tuesday, and Stumble-On deposits, and those in the Moira Sound unit include the Barrier Islands, Moira Copper, Niblack, and Nichols Bay deposits. Pb-isotopic signatures were determined on sulfide minerals (galena, pyrite, chalcopyrite, pyrrhotite, and sphalerite) to constrain metal sources of the massive sulfides and for comparison with data for other deposits in the region. Except for the Ruby Tuesday deposit, galena is relatively rare in most of these deposits. Pb-isotopic signatures distinguish the mainly Cu+Zn±Ag±Au massive sulfide deposits in the Wales Group from the Zn+Cu±Ag±Au massive sulfide deposits in the Moira Sound unit. Among the older group of deposits, the Khayyam deposit has the widest variation in Pb-isotopic ratios (206Pb/204Pb=17.169–18.021, 207Pb/204Pb=15.341–15.499, 208Pb/204Pb=36.546–37.817); data for the other massive sulfide deposits in the Wales Group overlap the isotopic variations in the Khayyam deposit. Pb-isotopic ratios for both groups of deposits are lower than those on the average crustal Pbevolution curve (µ=9.74), attesting to a large mantle influence in the Pb source. All the deposits show no evidence for Pb evolution primarily in the upper or lower continental crust. Samples from the younger group of deposits have scattered Pb-isotopic compositions and plot as a broad band on uranogenic and thorogenic Pb diagrams. Data for these deposits overlap the trend for massive sulfide deposits in the Wales Group but extend to significantly more radiogenic Pb-isotopic values. Pb-isotopic ratios of

  2. Structure of ²⁰⁷Pb populated in ²⁰⁸Pb + ²⁰⁸Pb deep-inelastic collisions*

    DOE PAGES

    Shand, C. M.; Wilson, E.; Podolyák, Zs.; ...

    2015-01-01

    The yrast structure of 207Pb above the 13/2+ isomeric state has been investigated in deep-inelastic collisions of 208Pb and 208Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of 207Pb is presented up to ~ 6 MeV, built using coincidence and γ-ray intensity analyses. In addition, the spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations.

  3. Nondestructive identification of isotopes using nuclear resonance fluorescence

    SciTech Connect

    Shizuma, Toshiyuki; Hayakawa, Takehito; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Ohgaki, Hideaki; Toyokawa, Hiroyuki

    2012-01-15

    Nondestructive identification of heavy isotopes concealed in a thick iron box has been demonstrated by using nuclear resonance fluorescence. A quasi-monochromatic photon beam produced by the collision of laser quanta with high energy electrons was used for resonant excitation of nuclear levels in {sup 206}Pb and {sup 208}Pb. By measuring the resonant {gamma} rays emitted from {sup 206}Pb and {sup 208}Pb, each of these isotopes were clearly identified. The ratio of the effective thickness, i.e., concentration distribution, of these isotopes was deduced from the relative intensities of the measured nuclear resonance fluorescence strengths.

  4. Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

    SciTech Connect

    Gaffney, A M; Borg, L E; Connelly, J N

    2006-12-22

    Uranium-lead ratios (commonly represented as {sup 238}U/{sup 204}Pb = {mu}) calculated for the sources of martian basalts preserve a record of petrogenetic processes that operated during early planetary differentiation and formation of martian geochemical reservoirs. To better define the range of {mu} values represented by the source regions of martian basalts, we completed U-Pb elemental and isotopic analyses on whole rock, mineral and leachate fractions from the martian meteorite Queen Alexandra Range 94201 (QUE 94201). The whole rock and silicate mineral fractions have unradiogenic Pb isotopic compositions that define a narrow range ({sup 206}Pb/{sup 204}Pb = 11.16-11.61). In contrast, the Pb isotopic compositions of weak HCl leachates are more variable and radiogenic. The intersection of the QUE 94201 data array with terrestrial Pb in {sup 206}Pb/{sup 204}Pb-{sup 207}Pb/{sup 204}Pb-{sup 208}Pb/{sup 204}Pb compositional space is consistent with varying amounts of terrestrial contamination in these fractions. We calculate that only 1-7% contamination is present in the purified silicate mineral and whole rock fractions, whereas the HCl leachates contain up to 86% terrestrial contamination. Despite the contamination, we are able to use the U-Pb data to determine the initial {sup 206}Pb/{sup 204}Pb of QUE 94201 (11.086 {+-} 0.008) and calculate the {mu} value of the QUE 94201 mantle source to be 1.823 {+-} 0.008. This is the lowest {mu} value calculated for any martian basalt source, and, when compared to the highest values determined for martian basalt sources, indicates that {mu} values in martian source reservoirs vary by at least 100%. The range of source {mu} values further indicates that the {mu} value of bulk silicate Mars is approximately three. The amount of variation in the {mu} values of the mantle sources ({mu} {approx} 2-4) is greater than can be explained by igneous processes involving silicate phases alone. We suggest the possibility that a small

  5. Surface dust wipes are the best predictors of blood leads in young children with elevated blood lead levels

    SciTech Connect

    Gulson, Brian; Anderson, Phil; Taylor, Alan

    2013-10-15

    Background: As part of the only national survey of lead in Australian children, which was undertaken in 1996, lead isotopic and lead concentration measurements were obtained from children from 24 dwellings whose blood lead levels were ≥15 µg/dL in an attempt to determine the source(s) of their elevated blood lead. Comparisons were made with data for six children with lower blood lead levels (<10 µg/dL). Methods: Thermal ionisation and isotope dilution mass spectrometry were used to determine high precision lead isotopic ratios ({sup 208}Pb/{sup 206}Pb, {sup 207}Pb/{sup 206}Pb and {sup 206}Pb/{sup 204}Pb) and lead concentrations in blood, dust from floor wipes, soil, drinking water and paint (where available). Evaluation of associations between blood and the environmental samples was based on the analysis of individual cases, and Pearson correlations and multiple regression analyses based on the whole dataset. Results and discussion: The correlations showed an association for isotopic ratios in blood and wipes (r=0.52, 95% CI 0.19–0.74), blood and soil (r=0.33, 95% CI −0.05–0.62), and blood and paint (r=0.56, 95% CI 0.09–0.83). The regression analyses indicated that the only statistically significant relationship for blood isotopic ratios was with dust wipes (B=0.65, 95% CI 0.35–0.95); there were no significant associations for lead concentrations in blood and environmental samples. There is a strong isotopic correlation of soils and house dust (r=0.53, 95% CI 0.20–0.75) indicative of a common source(s) for lead in soil and house dust. In contrast, as with the regression analyses, no such association is present for bulk lead concentrations (r=−0.003, 95% CI −0.37–0.36), the most common approach employed in source investigations. In evaluation of the isotopic results on a case by case basis, the strongest associations were for dust wipes and blood. -- Highlights: • Children with elevated blood lead ≥15 µg/dL compared with a group with <10

  6. Long-Term Performance of Pb Isotopic Analysis by TIMS with 202Pb-205Pb Double Spike

    NASA Astrophysics Data System (ADS)

    Amelin, Y.; Connelly, J. N.

    2008-05-01

    The 202Pb-205Pb-233U-235U spike (Pb DS), prepared at the Geological Survey of Canada in 2005 [1], and the 202Pb-205Pb-235U spike, prepared at the Department of Geosciences, University of Oslo [2], have been used for more than two years. Both spikes are routinely used for TIMS analysis of Pb with internal fractionation correction for U-Pb dating of various rocks and minerals, including dating perovskite [2] and meteorites and their components [1, 4-7]. A few hundred standard and sample Pb DS analyses were acquired with these two spikes using Triton TI mass spectrometers at the Geological Survey of Canada, US Geological Survey and the Australian National University, a Finnigan-MAT 261 mass spectrometer at The University of Texas at Austin and a Finnigan-MAT 262 mass spectrometer at the University of Oslo. All analyses were performed using high efficiency silicic acid emitter [8] and a static multicollector mode if the samples were sufficiently large to produce an ion beam greater than ca. 2-5×10-14 A on 206Pb and 207Pb. These data allow us to evaluate long - term performance of the Pb DS procedure for sub-nanogram samples of Pb. The performance of this procedure is evaluated on the basis of the long-term reproducibility of analyses of isotopic standards, and from improving quality of linear fits in Pb-Pb isochron diagrams (and, hence, improved precision of ages) compared to the same data reduced using external normalization. The data for 0.3 ng loads of SRM-981, analyzed with the batches of samples in 2006 and 2007 at the GSC, yield the mean 204Pb/206Pb of 0.05904±0.00013 (0.226% 2σ), #207Pb/206Pb of 0.91483±0.00018 (0.020% 2σ)), and 208Pb/206Pb of 2.16771±0.00054 (0.025% 2σ)). These values and errors are similar to those reported in [1] for the loads of the same size, and to the values obtained for similar loads at the USGS and at ANU over shorter periods of time. The precision and reproducibility of sample analysis and standard analyses is similar, and

  7. Pb isotopic composition of Paleozoic sediments derived from the Appalachian orogen

    SciTech Connect

    Krogstad, E.J. . Dept. of Geology)

    1993-03-01

    Differences in [sup 207]Pb/[sup 204]Pb at restricted ranges of [sup 206]Pb/[sup 204]Pb are robust indicators of differences in the earliest history of crust or mantle reservoirs, surviving later changes in U/Pb that may be due to melting, metamorphism, or sedimentary reworking. Ayuso and Bevier (1991) have used the [sup 207]Pb/[sup 204]Pb differences between Late Paleozoic granites in the N. Appalachians to trace their sources in either Laurentian (Grenville) lithosphere, or docked (Avalonian) lithosphere. If the Pb isotopic composition of Avalonian lithosphere is unique to that source among all lithospheric reservoirs in the Appalachian orogeny, the sediments shed off the orogen should record the first appearance of rocks with this extraneous Pb isotopic composition as they become accreted. The high [sup 207]Pb/[sup 204]Pb at similar [sup 206]Pb/[sup 204]Pb that may be indicative of all outboard terranes occurs in sedimentary rocks younger than middle Ordovician in New York and Maine, and younger than Ordovician in Virginia. Older sediments (Hadrynian, Cambrian), as well as autochthonous basement and paraautochonous basement slices, have lower [sup 207]Pb/[sup 204]Pb at similar [sup 206]Pb/[sup 204]Pb. The low [sup 207]Pb/[sup 204]Pb at similar [sup 206]Pb/[sup 204]Pb shown by these rocks may be a locally diagnostic signature of Late Proterozoic Laurentian lithosphere. The high [sup 207]Pb/[sup 204]Pb at similar [sup 206]Pb/[sup 204]Pb may be a locally diagnostic signature of Late Proterozoic accreted terranes. Rocks with accreted terrane Pb isotopic composition became dominant in the provenance of sediments along the strike of the Appalachian orogen by middle Ordovician time.

  8. A century long sedimentary record of anthropogenic lead (Pb), Pb isotopes and other trace metals in Singapore.

    PubMed

    Chen, Mengli; Boyle, Edward A; Switzer, Adam D; Gouramanis, Chris

    2016-06-01

    Reconstructing the history of metal deposition in Singapore lake sediments contributes to understanding the anthropogenic and natural metal deposition in the data-sparse Southeast Asia. To this end, we present a sedimentary record of Pb, Pb isotopes and eleven other metals (Ag, As, Ba, Cd, Co, Cr, Cu, Ni, Tl, U and Zn) from a well-dated sediment core collected near the depocenter of MacRitchie Reservoir in central Singapore. Before the 1900s, the sedimentary Pb concentration was less than 2 mg/kg for both soil and sediment, with a corresponding (206)Pb/(207)Pb of ∼1.20. The Pb concentration increased to 55 mg/kg in the 1990s, and correspondingly the (206)Pb/(207)Pb decreased to less than 1.14. The (206)Pb/(207)Pb in the core top sediment is concordant with the (206)Pb/(207)Pb signal of aerosols in Singapore and other Southeast Asian cities, suggesting that Pb in the reservoir sediment was mainly from atmospheric deposition. Using the Pb concentration in the topmost layer of sediment, the estimated atmospheric Pb flux in Singapore today is ∼1.6 × 10(-2) g/m(2) yr. The concentrations of eleven other metals preserved in the sediment were also determined. A principal component analysis showed that most of the metals exhibit an increasing trend towards 1990s with a local concentration peak in the mid-20(th) century.

  9. Role of oceanic circulation on contaminant lead distribution in the South Atlantic

    NASA Astrophysics Data System (ADS)

    Alleman, L. Y.; Church, T. M.; Ganguli, P.; Véron, A. J.; Hamelin, B.; Flegal, A. R.

    Both the relatively high lead concentrations and their characteristic anthropogenic isotopic compositions attest to the widespread contamination of industrial lead in the western Equatorial and South Atlantic Ocean. Spatial gradients in those isotopic signatures evidence the conservative lateral transport of lead in oceanic water masses, while the discrete isotopic signatures in deep oceanic waters substantiate the complementary hypothesis that the release of lead from settling particles is relatively small on a decadal time-scale. Specifically, the relatively low radiogenic lead (e.g., 206Pb/ 207Pb=1.148±0.009) in the Lower-North Atlantic Deep Water (l-NADW) south of 10° North is primarily attributed to US industrial lead emitted in the Northern Hemisphere prior to 1965, and the more radiogenic lead (e.g., 206Pb/ 207Pb=1.180±0.006) in the Upper-North Atlantic Deep Water (u-NADW) is primarily attributed to subsequent industrial lead emissions in that hemisphere. In contrast, the relatively radiogenic lead (e.g., 206Pb/ 207Pb=1.186±0.007) in the Antarctic Bottom Water (AABW) seemingly reflects a mixture of natural and anthropogenic lead sources within the Southern Hemisphere; and its isotopic dissimilarity with that (e.g., 206Pb/ 207Pb=1.159±0.002) of Antarctic Intermediate Water (AAIW) and the AABW may be due to differences in either their aeolian or water-mass inputs.

  10. Isotopic tracing of landfill leachates and pollutant lead mobility in soil and groundwater.

    PubMed

    Vilomet, J D; Veron, A; Ambrosi, J P; Moustier, S; Bottero, J Y; Chatelet-Snidaro, L

    2003-10-15

    Here we provide evidence of the capability of stable lead isotopes to trace landfill leachate in a shallow groundwater. The municipal landfill we have investigated is located in southeastern France. It has no bottom liner, and wastes are placed directly on the ground. Stable lead isotopes allow the characterization of this landfill leachate signature (206Pb/207Pb = 1.189 +/- 0.004) that is clearly different from that of the local atmosphere (206Pb/207Pb = 1.150 +/- 0.006) and crustal lead (206Pb/207Pb = 1.200 +/- 0.005). Piezometers located in the direct vicinity of the landfill generally display this contaminant imprint. The landfill plume is monitored up to 1000 m downgradient of the landfill, in very good agreement with evaluation from chloride concentration. Meanwhile, 206Pb/207Pb ratios measured at a piezometer located 4600 m downgradient of the landfill suggest a contamination by the landfill plume. This result shows that the complexity of a pollutant plume dispersion in this shallow groundwater system requires several independent tracers to clearly resolve origin and transport pathways for contaminants. Furthermore, seasonal rainfall variation for this Mediterranean mixed Quaternary alluvion reservoir and the use of KCl fertilizers might favor an efficient remobilization of atmospheric lead in plowed soils and its transfer into groundwater as shown by lead isotope systematics.

  11. Lead isotope ratios in bone ash of blesbok (Damaliscus pygargus phillipsi): a means of screening for the accumulation of contaminants from uraniferous rocks.

    PubMed

    Nöthling, Johan O; Du Toit, Johannes S; Myburgh, Jan G

    2014-09-19

    This study was done to determine whether blesbok (Damaliscus pygargus phillipsi) from the Krugersdorp Game Reserve (KGR) in Gauteng Province, South Africa have higher concentrations of (238)U and higher (206)Pb/(204)Pb and (207)Pb/(204)Pb ratios in their bone ash than blesbok from a nearby control reserve that is not exposed to mine water and has no outcrops of uraniferous rocks. Eight blesbok females from the KGR and seven from the control site, all killed with a brain shot, were used. A Thermo X-series 2 quadrupole ICPMS was used to measure the concentrations of (238)U and lead and a Nu Instruments NuPlasma HR MC-ICP-MS to measure the lead isotope ratios in the tibial ash from each animal. KGR blesbok had higher mean concentrations of (238)U (P = 0.02) and ratios of (206)Pb/(204)Pb and (207)Pb/(204)Pb (P < 0.00001) than the control blesbok. The probability of rejecting the false null hypothesis of no difference in the (206)Pb/(204)Pb or (207)Pb/(204)Pb ratios between KGR and control reserve animals (the power of the test) was 0.999. The blesbok from the KGR accumulated contaminants from an uraniferous environment. The (206)Pb/(204)Pb and (207)Pb/(204)Pb ratios in tibial ash proved effective in confirming accumulation of contaminants from uraniferous rocks.

  12. Isotopic evidence from lavas and mantle xenoliths for a mixed asthenospheric-lithospheric source for Rio Grande rift magmas

    NASA Astrophysics Data System (ADS)

    Chatterjee, R. N.; Byerly, B. L.; Lassiter, J. C.

    2011-12-01

    Lavas from the Rio Grande rift have a wide range of isotopic compositions from MORB-like to OIB and further enriched values. Most previous studies have interpreted this as reflecting variable melt derivation from asthenospheric and lithospheric mantle sources with temporal evolution related to thinning or delamination of the lithosphere associated with rifting. Alternatively, Wolff et al. (2005) and Crocker et al. (2010) have argued for strong crustal overprinting of the lavas; which swamps the mantle signature and limits our understanding of the mantle evolution beneath the rift. We have examined lavas and mantle xenoliths from West Potrillo, Elephant Butte and Cerro Chato localities of the rift in order to investigate whether the mantle beneath the rift possesses the isotopic signature of the lavas or if crustal inputs are required to explain the enrichments in the lavas. The lavas display a wide range of isotopic composition with 87Sr/86Sr (0.702990-0.704936), 143Nd/144Nd (0.512745-0.512973), 206Pb/204Pb (18.66-19.93), 207Pb/204Pb (15.54-15.66) and 208Pb/204Pb (38.32-39.53). The Elephant Butte lavas are more enriched than the West Potrillo lavas. Clinopyroxene separates from the mantle xenoliths have 87Sr/86Sr (0.701756-0.704455), 143Nd/144Nd (0.512880-0.514040), 206Pb/204Pb (17.99-19.52), 207Pb/204Pb (15.39-15.68) and 208Pb/204Pb (37.46-39.22). The Elephant Butte xenoliths have depleted mantle-like compositions while the Cerro Chato xenoliths are chemically similar to SCLM. The lavas lie on a mixing line between these two end-members in Sr-Nd-Pb space. The isotopic ratios of the lavas are correlated with Sm/Yb, La/Sm and Ba/Nb ratios, which are generally more sensitive to melting processes rather than crustal assimilation. Indices of fractional crystallization such as SiO2 and Mg# are not correlated with the isotopic ratios. The West Potrillo lavas generally have lower SiO2 and higher Sm/Yb compared to Elephant Butte, likely due to a greater depth of melt

  13. Geochemical and geochronological constraints on the genesis of Au-Te deposits at Cripple Creek, Colorado

    USGS Publications Warehouse

    Kelley, K.D.; Romberger, S.B.; Beaty, D.W.; Pontius, J.A.; Snee, L.W.; Stein, H.J.; Thompson, T.B.

    1998-01-01

    The Cripple Creek district (653 metric tons (t) of Au) consists of Au-Te veins and disseminated gold deposits that are spatially related to alkaline igneous rocks in an Oligocene intrusive complex. Vein paragenesis includes quartz-biotite-K feldspar-fluorite-pyrite followed by base metal sulfides and telluride minerals. Disseminated deposits consist of microcrystalline native gold with pyrite that are associated with zones of pervasive adularia. New 40Ar/39Ar dates indicate that there was a complex magmatic and hydrothermal history. Relatively felsic rocks (tephriphonolite, trachyandesite, and phonolite) were emplaced into the complex over about 1 m.y., from 32.5 ?? 0.1 (1??) to 31.5 ?? 0.1 Ma. A younger episode of phonolite emplacement outside of the complex is indicated by an age of 30.9 ?? 0.1 Ma. Field relationships suggest that at least one episode of mafic and ultramafic dike emplacement occurred after relatively more felsic rocks and prior to the main gold mineralizing event. Only a single whole-rock date for mafic phonolite (which indicated a maximum age of 28.7 Ma) was obtained. However, constraints on the timing of mineralization are provided by paragenetically early vein minerals and K feldspar from the disseminated gold pyrite deposits. Early vein minerals (31.3 ?? 0.1-29.6 ?? 0.1 Ma) and K feldspar (29.8 ?? 0.1 Ma) from the Cresson disseminated deposit, together with potassically altered phonolite adjacent to the Pharmacist vein (28.8 and 28.2 ?? 0.1 Ma), suggest there was a protracted history of hydrothermal activity that began during the waning stages of phonolite and early mafic-ultramafic activity and continued, perhaps intermittently, for at least 2 m.y. Estimated whole-rock ??18O values of the alkaline igneous rocks range from 6.4 to 8.2 per mil. K feldspar and albite separates from igneous rocks have lead isotope compositions of 206Pb/204Pb = 17.90 to 18.10, 207Pb/204Pb = 15.51 to 15.53, and 208Pb/204Pb = 38.35 to 38.56. These isotopic

  14. Coexistence of galenas with different Pb isotopic composition in Los Pedroches batholith area (Spain)

    NASA Astrophysics Data System (ADS)

    García de Madinabeitia, S.; Santos Zalduegui, J. F.; Larrea, F. J.; Carracedo, M.; Gil Ibarguchi, J. I.

    2003-04-01

    The Los Pedroches batholith region (S Spain) includes three separated mining districts: Linares, La Carolina and Los Pedroches. The Pb isotopic composition of thirty-three galenas from this sector has been measured. On the basis of the Pb data two types of mineralization are established. A first type including: (i) the Linares and La Carolina districts where ore-bearing filons cut Hercynian granites or their hostrocks (SE of the batholith), and (ii) the so-called "peribatholithic" ore bodies represented by scarce mines in the host-rock of the batholith; all of them exhibit homogeneous Pb isotopic compositions of: 206Pb/204Pb = 18.236, 207Pb/204Pb = 15.615, 208Pb/204Pb = 38.347 and a model age of ca. 324 Ma. The second type is represented by a huge N120^oE hydrotermal vein (the El Zumajo vein) intrusive in granitoid bodies of the batholith; the Pb isotopic composition of the vein is: 206Pb/204Pb = 18.457, 207Pb/204Pb = 15.636, 208Pb/204Pb = 38.611 and a model age of ca. 201 Ma. Analysed K-feldspars from batholithic granodiorite and granites have Pb isotopic compositions similar to those reported previously from Hercynian granites of the area (1) and to the galenas of Linares, La Carolina and "peribatholithic" ores. The whole dataset reveals a Pb evolution curve with μ_2 = 9.8 and ω_2 = 38.3, close to the model curve for the "orogen" (2). This suggests for Linares, La Carolina and the "peribatholithic" mineralizations a Pb source related to that of the granites. The pre-Tremadoc metasedimentary rocks of the area, with Pb isotopic composition (3) very close to that of feldspars and galenas studied is proposed as a possible source of Pb for both the granites and associated mineralizations, although the Pb isotopic composition of El Zumajo calls for a different origin. The observed difference in Pb isotopic ratios of the studied galenas points to, at least, two ore-forming events: (i) one relating older mineralizations and granitoid intrusives, in agreement with

  15. Sr, Nd and Pb isotope and geochemical data from the Quaternary Nevado de Toluca volcano, a source of recent adakitic magmatism, and the Tenango Volcanic Field, Mexico

    NASA Astrophysics Data System (ADS)

    Martínez-Serrano, Raymundo G.; Schaaf, Peter; Solís-Pichardo, Gabriela; Hernández-Bernal, Ma. del Sol; Hernández-Treviño, Teodoro; Julio Morales-Contreras, Juan; Macías, José Luis

    2004-11-01

    Volcanic activity at Nevado de Toluca (NT) volcano began 2.6 Ma ago with the emission of andesitic lavas, but over the past 40 ka, eruptions have produced mainly lava flows and pyroclastic deposits of predominantly orthopyroxene-hornblende dacitic composition. In the nearby Tenango Volcanic Field (TVF) pyroclastic products and lava flows ranging in composition from basaltic andesite to andesite were erupted at most of 40 monogenetic volcanic centers and were coeval with the last stages of NT. All volcanic rocks in the study area are characterized by a calc-alkaline affinity that is consistent with a subduction setting. Relatively high concentrations of Sr (>460 ppm) coupled with low Y (<21 ppm), along with relatively low HREE contents and Pb isotopic values similar to MORB-EPR, suggest a possible geochemical adakitic signature for the majority of the volcanic rocks of NT. The HFS- and LIL-element patterns for most rocks of the TVF suggest a depleted source in the subcontinental lithosphere modified by subduction fluids, similar to most rocks from the Trans-Mexican Volcanic Belt (TMVB). The isotopic compositions are similar for volcanic rocks of NT and TVF regions ( 87Sr/ 86Sr: 0.703853-0.704226 and 0.703713-0.704481; ɛNd: +4.23-+5.34 and +2.24-+6.85; 206Pb/ 204Pb: 18.55-18.68 and 18.58-18.69; 207Pb/ 204Pb: 15.54-15.62 and 15.56-15.61; 208Pb/ 204Pb: 38.19-38.47 and 38.28-38.50, respectively), suggesting a MORB-like source with low crustal contamination. Metamorphic xenoliths from deeper continental crust beneath NT volcano show isotopic patterns similar to those of Grenvillian rocks of north-central Mexico ( 87Sr/ 86Sr: 0.715653-0.721984, ɛNd: -3.8 to -7.2, 206Pb/ 204Pb: 18.98-19.10, 207Pb/ 204Pb: 15.68-15.69, 208Pb/ 204Pb: 39.16-39.26 and Nd model age (T DM) of 1.2-1.3 Ga). In spite of a thick continental crust (>45 km) that underlies the volcanoes of the study area, the geochemical and isotopic patterns of these rocks indicate low interaction with this crust. NT

  16. Two Distinct Sets of Magma Sources in Cretaceous Rocks From Magnet Cove, Prairie Creek, and Other Igneous Centers of the Arkansas Alkaline Province, USA

    NASA Astrophysics Data System (ADS)

    Duke, G. I.; Carlson, R. W.; Eby, G. N.

    2008-12-01

    Two distinct sets of magma sources from the Arkansas alkaline province (~106-89 Ma) are revealed by Sr-Nd-Pb isotopic compositions of olivine lamproites vs. other alkalic rock types, including carbonatite, ijolite, lamprophyres, tephrite, malignite, jacupirangite, phonolite, trachyte, and latite. Isotopic compositions of diamond-bearing olivine lamproites from Prairie Creek and Dare Mine Knob point to Proterozoic lithosphere as an important source, and previous Re-Os isotopic data indicate derivation from subcontinental mantle lithosphere. Both sources were probably involved in lamproite generation. Magnet Cove carbonatites and other alkalic magmas were likely derived from an asthenospheric source. Lamproite samples are isotopically quite different from other rock types in Sr-Nd-Pb isotopic space. Although three lamproite samples from Prairie Creek have a large range of SiO2 contents (40-60 wt %), initial values of ɛNd (-10 to -13), 206Pb/204Pb (16.61-16.81), 207Pb/204Pb (15.34-15.36), and 208Pb/204Pb (36.57-36.76) are low and similar. Only 87Sr/86Sr(i) displays a wide range in the Prairie Creek lamproites (0.70627-0.70829). A fourth lamproite from Dare Mine Knob has the most negative ɛNd(i) of -19. Lamproite isotope values show a significant crustal component and isotopically overlap subalkalic rhyolites from the Black Hills (SD), which assimilated Proterozoic crust. Six samples of carbonatite, ijolite, and jacupirangite from Magnet Cove and Potash Sulphur Springs exhibit the most depleted Sr-Nd isotopic signatures of all samples. For these rock types, 87Sr/86Sr(i) is 0.70352 - 0.70396, and ɛNd(i) is +3.8 - +4.3. Eight other rock types have a narrow range of ɛNd(i) (+1.9 - +3.7), but a wide range of 87Sr/86Sr(i) (0.70424 - 0.70629). These 14 samples comprise a fairly tight cluster of Pb isotopic values: 206Pb/204Pb (18.22-19.23), 207Pb/204Pb (15.54-15.62), and 208Pb/204Pb (38.38-38.94), suggesting very little crustal assimilation. They are most similar to EM-2

  17. Triassic fluid mobilization and epigenetic lead-zinc sulphide mineralization in the Transdanubian Shear Zone (Pannonian Basin, Hungary)

    NASA Astrophysics Data System (ADS)

    Benkó, Zsolt; Molnár, Ferenc; Lespinasse, Marc; Billström, Kjell; Pécskay, Zoltán; Németh, Tibor

    2014-06-01

    A combined fluid inclusion, fluid inclusion plane, lead isotope and K/Ar radiometric age dating work has been carried out on two lead-zinc mineralizations situated along the Periadriatic-Balaton Lineament in the central part of the Pannonian Basin, in order to reveal their age and genetics as well as temporal-spatial relationships to other lead-zincfluorite mineralization in the Alp-Carpathian region. According to fluid inclusion studies, the formation of the quartzfluorite- galena-sphalerite veins in the Velence Mts is the result of mixing of low (0-12 NaCl equiv. wt. %) and high salinity (10-26 CaCl2 equiv. wt. %) brines. Well-crystallized (R3-type) illite associated with the mineralized hydrothermal veins indicates that the maximum temperature of the hydrothermal fluids could have been around 250 °C. K/Ar radiometric ages of illite, separated from the hydrothermal veins provided ages of 209-232 Ma, supporting the Mid- to Late-Triassic age of the hydrothermal fluid flow. Fluid inclusion plane studies have revealed that hydrothermal circulation was regional in the granite, but more intensive around the mineralized zones. Lead isotope signatures of hydrothermal veins in the Velence Mts (206Pb/204Pb = 18.278-18.363, 207Pb/204Pb = 15.622-15.690 and 208Pb/204Pb = 38.439-38.587) and in Szabadbattyán (206Pb/204Pb = 18.286-18.348, 207Pb/204Pb = 15.667-15.736 and 208Pb/204Pb = 38.552-38.781) form a tight cluster indicating similar, upper crustal source of the lead in the two mineralizations. The nature of mineralizing fluids, age of the fluid flow, as well as lead isotopic signatures of ore minerals point towards a genetic link between epigenetic carbonate-hosted stratiform-stratabound Alpine-type lead-zinc-fluorite deposits in the Southern and Eastern Alps and the studied deposits in the Velence Mts and at Szabadbattyán. In spite of the differences in host rocks and the depth of the ore precipitation, it is suggested that the studied deposits along the Periadriatic

  18. Isotopic composition of Late Mesozoic basic and ultrabasic rocks from the Andes (23-32°S) - implications for the Andean mantle

    NASA Astrophysics Data System (ADS)

    Lucassen, Friedrich; Escayola, Monica; Romer, Rolf; Viramonte, José; Koch, Kerstin; Franz, Gerhard

    2002-02-01

    Mesozoic mantle-derived magmatic rocks from the Jurassic-Early Cretaceous active continental margin of N Chile near 24°S, and from the Cretaceous rift system of NW Argentina near 26°S (central rift) and 32°S (southern rift) are used to constrain the isotopic composition of mantle reservoirs before the onset of the Cenozoic Andean orogeny. They are largely uncontaminated by assimilation of the local Palaeozoic basement as seen in the major and trace element patterns and Sr and Nd isotopic composition of most samples, but small amounts of crustal contamination are detected in the Pb isotope composition. Two different types of mantle sources have been identified. (1) For rocks from the Jurassic arc, now at the continental margin at 24°S, and for rocks from the central rift at 26°S, a depleted mantle source with 143Nd/144Nd(t) 0.5127-0.5128, 87Sr/86Sr(t) ca. 0.7033 may be inferred. Pb isotopic ratios of most samples from the magmatic arc are overall less radiogenic than those from the rift (206Pb/204Pb(t) ca. 18.0-18.4 vs. 18.1-19.1, 207Pb/204Pb(t) 15.55-15.59 vs 15.58-15.64 and 208Pb/204Pb(t) 37.8-38.6 vs. 38.4-38.9). (2) In the southern rift at ca. 30-32°S [Sierras Los Cóndores region (LC) and Sierras Chaján region (Ch)], an enriched mantle source has been identified, which is similar to the composition of the mantle lithosphere beneath the Brazilian Shield. Samples from LC and Ch show some isotopic differences because of varying degrees of crustal contamination in the LC samples. The LC samples have a higher Th/U ratio than the Ch samples and different Pb isotopic ratios 206Pb/204Pb(t) 18.0-18.6 (LC) vs. 17.7 and 17.8 (Ch), 207Pb/204Pb(t) 15.50-15.66 (LC) vs. 15.50 (Ch) and 208Pb/204Pb(t) 38.6-39.2 (LC) vs. ca. 37.5 (Ch). The Nd isotopic ratios of LC and Ch samples are similar 143Nd/144Nd(t) 0.5123-0.5122 (LC) vs. 0.5123 (Ch), whereas their Sr isotopic ratios differ 87Sr/86Sr(t) 0.7054-0.7079 (LC) vs. ca. 0.704 (Ch). Electronic supplementary material to this

  19. Alpha / Mendeleev Ridge and Chukchi Borderland 40Ar/39Ar Geochronology and Geochemistry: Character of the First Submarine Intraplate Lavas Recovered from the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Mukasa, Samuel B.; Mayer, Larry A.; Aviado, Kimberly; Bryce, Julie; Andronikov, Alex; Brumley, Kelley; Blichert-Toft, Janne; Petrov, Oleg; Shokalsky, Sergey

    2015-04-01

    At least three episodes of magmatic activity have been recognized on the basis of 40Ar/39Ar age determinations in the submarine basaltic samples dredged, drilled or grabbed with a manipulation arm from Alpha / Mendeleev Ridge and Chukchi Borderland of the Arctic Ocean by US Coast Guard Icebreaker Healy, in August-September 2008, and Russian research vessel Captain Dranitsin in August-October 2012: ca. 112 Ma, ca. 100 Ma and ca. 85-73 Ma. Major-oxide and trace-element concentrations, and Pb, Sr, Nd, and Hf isotopic ratios of the recovered lavas provide important constraints on the composition and sources for the original melts. Lavas erupted at ca. 112 Ma (Group 1) have alkali basalt major-oxide compositions. Their low degree of rare-earth-element (REE) fractionation (CeN/YbN = 1.7-2.5), combined with high overall HREE (22-24 times chondrite) and Mg# ~54, suggest derivation from a garnet-free source followed by only minimal crystal fractionation for this group. Pb-Sr-Nd-Hf isotopic systematics of the lavas (206Pb/204Pb = 18.73-18.79; 207Pb/204Pb = 15.54-15.56; 208Pb/204Pb = 38.28-38.35; 143Nd/144Nd = 0.512594-0.512610; 87Sr/86Sr = 0.709458-0.709601; 176Hf/177Hf = 0.283224), together with ratios of highly incompatible trace elements (Th/Ce = 0.09-0.11; Ce/Nb = 2.58-3.09; Th/Nb = 0.24-0.33), point toward a lithospheric source for the magmas. Eruptions at ca. 100 Ma and 85-73 Ma produced two types of lavas: low-Ti tholeiitic basalts - LT, and high-Ti alkali basalts - HT, both assigned to Group 2. This distribution of low- and high-Ti lavas is common in continental flood basalt (CFB) provinces elsewhere, and has been attributed to plume activity in some studies. The trace-element abundance patterns for these Group 2 Arctic lavas are also very similar to those of CFBs elsewhere. Their low degrees of REE fractionation (CeN/YbN = 2.0-3.3) accompanied by progressively decreasing Mg#s (from 53 to 33) suggest a garnet-free source, with the derivative magmas experiencing

  20. Origin of lead in eight Central European peat bogs determined from isotope ratios, strengths, and operation times of regional pollution sources.

    PubMed

    Novák, Martin; Emmanuel, Simon; Vile, Melanie A; Erel, Yigal; Véron, Alain; Paces, Tomás; Wieder, R Kelman; Vanecek, Mirko; Stepánová, Markéta; Brízová, Eva; Hovorka, Jan

    2003-02-01

    Lead originating from coal burning, gasoline burning, and ore smelting was identified in 210Pb-dated profiles through eight peat bogs distributed over an area of 60,000 km2. The Sphagnum-dominated bogs were located mainly in mountainous regions of the Czech Republic bordering with Germany, Austria, and Poland. Basal peat 14C-dated at 11,000 years BP had a relatively high 206Pb/207Pb ratio (1.193). Peat deposited around 1800 AD had a lower 206Pb/207Pb ratio of 1.168-1.178, indicating that environmental lead in Central Europe had been largely affected by human activity (smelting) even before the beginning of the Industrial Revolution. Five of the sites exhibited a nearly constant 206Pb/207Pb ratio (1.175) throughout the 19th century, resembling the "anthropogenic baseline" described in Northern Europe (1.17). At all sites, the 206Pb/207Pb ratio of peat decreased at least until 1980; at four sites, a reversal to more radiogenic values (higher 206Pb/207Pb), typical of easing pollution, was observed in the following decade (1980-1990). A time series of annual outputs for 14 different mining districts dispersing lead into the environment has been constructed for the past 200 years. The production of Ag-Pb, coal, and leaded gasoline peaked in 1900, 1980, and 1980, respectively. In contrast to other European countries, no peak in annual Pb accumulation rates was found in 1900, the year of maximum ore smelting. The highest annual Pb accumulation rates in peat were consistent with the highest Pb emission rates from coal-fired power plants and traffic (1980). Although maximum coal and gasoline production coincided in time, their isotope ratios were unique. The mean measured 206Pb/207Pb ratios of local coal, ores, and gasoline were 1.19, 1.16, and 1.11, respectively. A considerable proportion of coal emissions, relative to gasoline emisions, was responsible for the higher 206Pb/207Pb ratios in the recent atmosphere (1.15) compared to Western Europe (1.10). As in West European

  1. A stable lead isotopic investigation of the use of sycamore tree rings as a historical biomonitor of environmental lead contamination.

    PubMed

    Patrick, Gavin J; Farmer, John G

    2006-06-01

    The validity of the use of sycamore (Acer pseudoplatanus) tree-rings for the reconstruction of atmospheric lead pollution histories was investigated. Tree cores spanning 1892-2003 were collected from several sycamores from the eastern shore of Loch Lomond, Scotland, an area with no local point sources of lead emission. The lead concentration and 206Pb/207Pb profiles of the Loch Lomond region cores were compared with corresponding data for the 210Pb-dated loch sediment, and also with data for moss of known age from a Scottish herbarium collection. Two of the seven sycamore cores showed the same lead concentration trend as the lead flux to the loch, the rest having no similarity to either each other or the loch sediment record. Two further sycamore cores showed some similarity in their temporal 206Pb/207Pb trends to those seen in the sediment and moss records, but only in part of their profiles, whilst the 206Pb/207Pb ratios of the other sycamore cores remained relatively unchanged for the majority of the time covered, or exhibited an opposite trend. The 206Pb/207Pb ratios of the tree cores were also mostly higher than those of the previously established records for any given time period. Tree cores covering 1878-2002 were also collected along transects from Wanlockhead and Tyndrum, two areas of former lead mining and smelting associated with distinct 206Pb/207Pb ratios of 1.170 and 1.144, respectively. The Wanlockhead tree cores exhibited a generally decreasing trend in lead concentration with both time and distance from the lead mine. The characteristic 206Pb/207Pb ratio of 1.170 was observed in samples close to the mine but a decrease in the influence of the mine-derived lead was observed in more distant samples. The tree sampled at Tyndrum showed elevated lead concentrations, which decreased with time, and a fairly constant 206Pb/207Pb ratio of 1.15 reflecting input from the mine, features not observed in any other trees along the transect. Overall the data

  2. Early atmospheric metal pollution provides evidence for Chalcolithic/Bronze Age mining and metallurgy in Southwestern Europe.

    PubMed

    Martínez Cortizas, Antonio; López-Merino, Lourdes; Bindler, Richard; Mighall, Tim; Kylander, Malin E

    2016-03-01

    Although archaeological research suggests that mining/metallurgy already started in the Chalcolithic (3rd millennium BC), the earliest atmospheric metal pollution in SW Europe has thus far been dated to ~3500-3200 cal.yr. BP in paleo-environmental archives. A low intensity, non-extensive mining/metallurgy and the lack of appropriately located archives may be responsible for this mismatch. We have analysed the older section (>2100 cal.yr. BP) of a peat record from La Molina (Asturias, Spain), a mire located in the proximity (35-100 km) of mines which were exploited in the Chalcolithic/Bronze Age, with the aim of assessing evidence of this early mining/metallurgy. Analyses included the determination of C as a proxy for organic matter content, lithogenic elements (Si, Al, Ti) as markers of mineral matter, and trace metals (Cr, Cu, Zn, Pb) and stable Pb isotopes as tracers of atmospheric metal pollution. From ~8000 to ~4980 cal.yr. BP the Pb composition is similar to that of the underlying sediments (Pb 15 ± 4 μg g(-1); (206)Pb/(207)Pb 1.204 ± 0.002). A sustained period of low (206)Pb/(207)Pb ratios occurred from ~4980 to ~2470 cal.yr. BP, which can be divided into four phases: Chalcolithic (~4980-3700 cal.yr. BP), (206)Pb/(207)Pb ratios decline to 1.175 and Pb/Al ratios increase; Early Bronze Age (~3700-3500 cal.yr. BP), (206)Pb/(207)Pb increase to 1.192 and metal/Al ratios remain stable; Late Bronze Age (~3500-2800 cal.yr. BP), (206)Pb/(207)Pb decline to their lowest values (1.167) while Pb/Al and Zn/Al increase; and Early Iron Age (~2800-2470 cal.yr. BP), (206)Pb/(207)Pb increase to 1.186, most metal/Al ratios decrease but Zn/Al shows a peak. At the beginning of the Late Iron Age, (206)Pb/(207)Pb ratios and metal enrichments show a rapid return to pre-anthropogenic values. These results provide evidence of regional/local atmospheric metal pollution triggered by the earliest phases of mining/metallurgy in the area, and reconcile paleo-environmental and

  3. Human teeth as historical biomonitors of environmental and dietary lead: some lessons from isotopic studies of 19th and 20th century archival material.

    PubMed

    Farmer, J G; MacKenzie, A B; Moody, G H

    2006-10-01

    The lead isotopic composition of various sections (crown, crown base, root) of teeth was determined in specimens collected from 19th century skulls preserved in museum collections and, upon extraction or exfoliation, from humans of known ages residing in Scotland in the 1990s. For most 20th century samples, calculation of accurate crown-complete or root-complete dates of tooth formation ranging from the 1920s to the 1990s enabled comparison of (206)Pb/(207)Pb ratios for teeth sections (crown base root) with corresponding decadally averaged data for archival herbarium Sphagnum moss samples. This showed that the teeth sections had been significantly influenced by incorporation of non-contemporaneous (more recent) lead subsequent to the time of tooth formation, most probably via continuous uptake by dentine. This finding confirmed that separation of enamel from dentine is necessary for the potential of teeth sections as historical biomonitors of environmental (and dietary) lead exposure at the time of tooth formation to be realised. Nevertheless, the mean 19th century value of 1.172+/-0.007 for the (206)Pb/(207)Pb ratio in teeth was very similar to the corresponding mean value of 1.173+/-0.004 for 19th century archival moss, although relative contributions from environmental sources - whether direct, by inhalation/ingestion of dust contaminated by local lead smelting ((206)Pb/(207)Pb~1.17) and coal combustion ((206)Pb/(207)Pb~1.18) emissions, or indirect, through ingestion of similarly contaminated food - and drinking/cooking water contaminated by lead pipes of local origin, cannot readily be determined. In the 20th century, however, the much lower values of the (206)Pb/(207)Pb ratio (range 1.100-1.166, mean 1.126+/-0.013, median 1.124) for the teeth collected from various age groups in the 1990s reflect the significant influence of imported Australian lead of lower (206)Pb/(207)Pb ratio (~1.04) and released to the environment most notably through car

  4. Isotopic (Pb, Sr, Nd, C, O) evidence for plume-related sampling of an ancient, depleted mantle reservoir

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Simonetti, Antonio

    2015-02-01

    The exact mantle source for carbonatite melts remains highly controversial. Despite their predominant occurrence within continental (lithospheric) domains, the radiogenic isotope data from young (< 200 Ma) carbonatite complexes worldwide overlap the fields defined by present-day oceanic island basalts (OIBs). This feature suggests an intimate petrogenetic relationship with asthenospheric mantle. New Pb, Sr, C, and O isotopic data are reported here for constituent minerals from the Oka carbonatite complex, which is associated with the Cretaceous Monteregian Igneous Province (MIP), northeastern North America. The Pb isotope data define linear arrays in Pb-Pb isotope diagrams, with the corresponding Sr isotope ratios being highly variable (0.70314-0.70343); both these features are consistent with open system behavior involving at least three distinct mantle reservoirs. Compared to the isotope composition of known mantle sources for OIBs and carbonatite occurrences worldwide, the least radiogenic 207Pb/204Pb (14.96 ± 0.07) and 208Pb/204Pb (37.29 ± 0.15) isotopic compositions relative to their corresponding 206Pb/204Pb ratios (18.86 ± 0.08) reported here are distinct, and indicate the involvement of an ancient depleted mantle (ADM) source. The extremely unradiogenic Pb isotope compositions necessitate U/Pb fractionation early in Earth's history (prior to 4.0 Ga ago) and growth via a multi-stage Pb evolution model. The combined stable (C and O) and radiogenic isotopic compositions effectively rule out crustal/lithosphere contamination during the petrogenetic history of the Oka complex. Instead, the isotopic variations reported here most likely result from the mixing of discrete, small volume partial melts derived from a heterogeneous plume source characterized by a mixed HIMU-EM1-ADM signature.

  5. Trace Metals, Rare Earths, Carbon and Pb Isotopes as Proxies of Environmental Catastrophe at the Permian - Triassic Boundary in Spiti Himalayas, India

    NASA Astrophysics Data System (ADS)

    Ghosh, N.; Basu, A. R.; Garzione, C. N.; Ghatak, A.; Bhargava, O. N.; Shukla, U. K.; Ahluwalia, A. D.

    2015-12-01

    Himalayan sediments from Spiti Valley, India preserve geochemical signatures of the Permian - Triassic (P-Tr) mass extinction in the Neo-Tethys Ocean. We integrate new sedimentological and fossil record with high-resolution geochemical-isotopic data from Spiti that reveals an ecological catastrophe of global proportions. Trace elements of U, Th, Nb, Ta, Zr, Hf, the rare earths (REE) and carbon, oxygen and lead isotopes measured across the P-Tr boundary in Spiti are used as proxies for evaluating abrupt changes in this continental shelf environment. δ13Corg excursions of 2.4‰ and 3.1‰ in Atargu and Guling P-Tr sections in Spiti Valley are associated with an abrupt fall of biological productivity while δ13Ccarb and δ18Ocarb record of these sediments shows effects of diagenesis. Here, the P-Tr boundary is compositionally distinct from the underlying Late Permian gray shales, as a partly gypsiferous ferruginous layer that allows additional geochemical-isotopic investigation of sedimentary sources. Conspicuous Ce - Eu anomalies in the light REE-enriched Late Permian shales reflect the source composition of the adjacent Panjal Trap basalts of Kashmir. An abrupt change of this source to continental crust is revealed by Nb - Ta and Zr - Hf anomalies at the P-Tr ferruginous layer and continuing through the overlying Early Triassic carbonate rocks. Pb concentration and isotope ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb identify changes in the sedimentary element flux, distinguishing the Late Permian shales from the distinct siliciclastic continental crustal signature in the Early Triassic carbonates. These geochemical-isotopic constraints on the sedimentary geochemistry of one of the most critical transitions in geological record establish the utility of multi-proxy datasets for paleoenvironmental reconstructions.

  6. Measurements of Atmospheric Gaseous Mercury, Aerosol Trace Metals and Stable Lead Isotopes Over the South-Western Indian Ocean

    NASA Astrophysics Data System (ADS)

    Mather, T. A.; Witt, M. L.; Baker, A. R.; de Hoog, C.; Pyle, D. M.

    2008-12-01

    During November 2007, continuous measurements were made of total gaseous mercury (TGM) over the Indian Ocean during a two week cruise aboard the R/V Revelle from the Seychelles to Mauritius. Hg concentrations were consistently low during the cruise (1.0-1.4 ng m -3) similar to concentrations observed between 1994 and 2006 at an observatory in South Africa (Slemr et al., 2008). There was no significant diurnal signal observed during the cruise and the low variability in Hg is consistent with well mixed air masses and a long lifetime of Hg in the atmosphere. During this cruise size segregated and bulk aerosol samples were also collected using a high volume aerosol sampler. The aerosols were analysed for major ions, trace metals (Al, Fe, Ba, Mn, Co, V, Cr, Mo, Sr, Pb, Cd, As, Zn, Cu and Ni) and stable lead isotope ratios. The concentrations of most of the metals were similar to those observed in previous aerosol studies over similar regions of the Indian Ocean in 1986 (Chester et al., 1991) and 2002 (Witt et al., 2006). Aerosols were enriched above crustal and oceanic sources in many trace metals such as Pb, Cd, Ni and Zn although air mass back trajectories suggest air encountered had been over the ocean for at least 5 days prior to collection. Metal concentrations over the remote Indian Ocean appear to be intermediate between values reported for the remote Pacific and Atlantic oceans. Lead isotope ratios (206Pb, 207Pb and 208 Pb) in the aerosols fell into a group with a relatively radiogenic signature different to the Pb characteristic of Australian ores, where trajectories suggest air originated. The isotope ratios also differ to those observed in South African cities and are closer to the lead composition more typical of coals. Chester et al., (1991) Mar. Chem., 34; 261-290 Slemr et al., (2008) GRL, 35 (11) doi:10.1029/2008GL033741 Witt et al., (2006) Atmos. Env., 40; 5435-5451

  7. Dissolved lead in the deep Southeast Pacific Ocean: results of the 2013 US GEOTRACES cruise

    NASA Astrophysics Data System (ADS)

    Boyle, E. A.; Lee, J. M.; Zhang, J.; Echegoyen, Y.

    2014-12-01

    Lead (Pb) in the modern ocean is dominated by anthropogenic Pb, which has been evidenced by highly elevated seawater Pb concentrations and Pb stable isotope ratios (204Pb, 206Pb, 207Pb, and 208Pb) altered from pre-anthropogenic values. A number of studies have shown the human impact on oceanic Pb in many parts of the world ocean, but little Pb data has been available for the Southeast Pacific Ocean. In this presentation, we will show the dissolved Pb (<0.2µm) results from the US GEOTRACES cruise in October - December 2013, which sailed from Manta, Ecuador, to Tahiti along around 12 degrees south. Dissolved Pb concentrations from all 36 surface stations and deep (>1000m) Pb profiles from 18 stations will be presented, and the results will be also compared to our unpublished data from the BiG RAPA cruise in 2010, whose cruise track from Arica, Peru, to Easter Island is slightly south of the US GEOTRACES cruise. The BiG RAPA data showed that dissolved Pb concentrations of the southeast Pacific Ocean are relatively low, varying in the range of 8-20 pmol/kg at the surface with a slight maximum (14-22 pmol/kg) at around 400m depth, and 2-10 pmol/kg in deep waters below 1000m depth. The Pb concentrations were found to be higher at a marginal station off Peru, reaching 45 pmol/kg at the surface and 65 pmol/kg in the subsurface maximum at 150m depth, and varying between 17 and 23 pmol/kg in deep waters. Our dataset, along with the results from the BiG RAPA cruise, will provide the first overview on the dissolved Pb distribution of the southeast Pacific Ocean, which will further our understanding on the human impact on the global ocean.

  8. Plume-orogenic lithosphere interaction recorded in the Haladala layered intrusion in the Southwest Tianshan Orogen, NW China

    NASA Astrophysics Data System (ADS)

    He, Peng-Li; Huang, Xiao-Long; Xu, Yi-Gang; Li, Hong-Yan; Wang, Xue; Li, Wu-Xian

    2016-03-01

    The plume-orogenic lithosphere interaction may be common and important for the generation of large igneous provinces. The information regarding such a process is recorded by the Haladala gabbroic intrusion (~300 Ma), the largest layered ultramafic-mafic intrusion hosting V-Ti magnetite deposits in the Southwest Tianshan Orogen, NW China. The Haladala gabbros exhibit unfractionated chondrite-normalized rare earth element patterns with negative Nb and Ta anomalies and positive Pb anomaly on the primitive mantle-normalized multielement variation diagram. They are characterized by low initial Sr isotopes, slightly decoupled but high positive bulk rock ɛNd(t) and ɛHf(t), and high 207Pb/204Pb and 208Pb/204Pb relative to 206Pb/204Pb, delineating a DUPAL signature in the sources. The Haladala gabbros cannot be arc or postcollisional magmatism, given the lack of hydrous minerals and low K contents, respectively. This is further supported by the relatively low oxygen fugacity required for the gradual enrichment of V-Ti magnetite during the magma fractionation and by an overall anhydrous mantle source suggested by troctolite mineral assemblage (olivine + plagioclase). The emplacement age of the Haladala gabbros is identical to that of the Wajilitag kimberlites in the Tarim's interior, which have been interpreted as the first magmatic expression of the Tarim mantle plume. We thus propose that the Haladala gabbroic intrusion was generated in a hybrid geodynamic setting in which the Southwest Tianshan Orogen was impacted by an upwelling mantle plume. In this sense, the Haladala layered gabbroic intrusion records the early phase of magmatism of the Tarim plume, which was preferentially emplaced in a lithospheric weak zone.

  9. Petrogenesis and tectonic setting of the early Mesozoic Xitian granitic pluton in the middle Qin-Hang Belt, South China: Constraints from zircon U-Pb ages and bulk-rock trace element and Sr-Nd-Pb isotopic compositions

    NASA Astrophysics Data System (ADS)

    Wu, Qianhong; Cao, Jingya; Kong, Hua; Shao, Yongjun; Li, Huan; Xi, Xiaoshuang; Deng, Xuantong

    2016-10-01

    The Xitian pluton in southeast Hunan province is one of the early Mesozoic (Indosinian) granitic plutons in the South China Block. It is composed of biotite adamellite with K-feldspar megacrysts, biotite adamellite, and biotite granite that have U-Pb zircon ages of 229.9 ± 1.4 Ma, 223.6 ± 1.3 Ma, and 224.0 ± 1.4 Ma, respectively. The Indosinian granitoids in the Xitian pluton belong to S-type granites, with highly radiogenic initial 87Sr/86Sr ratios (0.71397-0.71910), negative εNd(t) values ranging from -10.1 to -9.4, and old Nd model ages (1858-1764 Ma). They are enriched in radiogenic Pb isotopes, with (206Pb/204Pb)t ranging from 18.130 to 18.903, (207Pb/204Pb)t from 15.652 to 15.722, and (208Pb/204Pb)t from 38.436 to 39.037, respectively. These features indicate that the granitoidswithin the Xitian pluton were formed from magmas generated by remelting of metapelite and metapsammite of the Paleoproterozoic metamorphic basement at temperatures of ca. 800 °C, with low oxygen fugacity. The Sr-Nd isotopic compositions of the rocks from Xitian pluton indicate that the granitic magmas were mixed with less than 10% mantle-derived magmas. We suggest that the Xitian pluton was emplaced in an extensional tectonic setting related to release of compressional stresses within the thickened crust during the early Mesozoic.

  10. Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment—The Obvious Source “Ain’t Necessarily So”

    PubMed Central

    Gulson, Brian; Korsch, Michael; Bradshaw, Anthony

    2016-01-01

    Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb) concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe) have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe) ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The source of the Broken Hill Pb is probably from the galvanized roofing material and/or brass fittings in the rainwater tanks. The discrimination between various sources is only detectable using high precision 204Pb-based isotopic ratios and not the now common inductively coupled plasma mass spectrometry (ICP-MS ) data presentations of the higher abundance isotopes 208Pb, 207Pb and 206Pb. Isotopic results for the waters demonstrate that apportioning blame where there is an obvious point source may not always be the correct conclusion. Nevertheless the isotopic data for the gutter wipes indicates that there was widespread contamination from the processing facilities throughout the town. PMID:26907319

  11. Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment--The Obvious Source "Ain't Necessarily So".

    PubMed

    Gulson, Brian; Korsch, Michael; Bradshaw, Anthony

    2016-02-22

    Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb) concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe) have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe) ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The source of the Broken Hill Pb is probably from the galvanized roofing material and/or brass fittings in the rainwater tanks. The discrimination between various sources is only detectable using high precision (204)Pb-based isotopic ratios and not the now common inductively coupled plasma mass spectrometry (ICP-MS ) data presentations of the higher abundance isotopes (208)Pb, (207)Pb and (206)Pb. Isotopic results for the waters demonstrate that apportioning blame where there is an obvious point source may not always be the correct conclusion. Nevertheless the isotopic data for the gutter wipes indicates that there was widespread contamination from the processing facilities throughout the town.

  12. Solving petrological problems through machine learning: the study case of tectonic discrimination using geochemical and isotopic data

    NASA Astrophysics Data System (ADS)

    Petrelli, Maurizio; Perugini, Diego

    2016-10-01

    Machine-learning methods are evaluated to study the intriguing and debated topic of discrimination among different tectonic environments using geochemical and isotopic data. Volcanic rocks characterized by a whole geochemical signature of major elements (SiO2, TiO2, Al2O3, Fe2O3T, CaO, MgO, Na2O, K2O), selected trace elements (Sr, Ba, Rb, Zr, Nb, La, Ce, Nd, Hf, Sm, Gd, Y, Yb, Lu, Ta, Th) and isotopes (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 87Sr/86Sr and 143Nd/144Nd) have been extracted from open-access and comprehensive petrological databases (i.e., PetDB and GEOROC). The obtained dataset has been analyzed using support vector machines, a set of supervised machine-learning methods, which are considered particularly powerful in classification problems. Results from the application of the machine-learning methods show that the combined use of major, trace elements and isotopes allows associating the geochemical composition of rocks to the relative tectonic setting with high classification scores (93 %, on average). The lowest scores are recorded from volcanic rocks deriving from back-arc basins (65 %). All the other tectonic settings display higher classification scores, with oceanic islands reaching values up to 99 %. Results of this study could have a significant impact in other petrological studies potentially opening new perspectives for petrologists and geochemists. Other examples of applications include the development of more robust geothermometers and geobarometers and the recognition of volcanic sources for tephra layers in tephro-chronological studies.

  13. Exotic lamproites or normal ultrapotassic rocks? The Late Miocene volcanic rocks from Kef Hahouner, NE Algeria, in the frame of the circum-Mediterranean lamproites

    NASA Astrophysics Data System (ADS)

    Lustrino, Michele; Agostini, Samuele; Chalal, Youcef; Fedele, Lorenzo; Stagno, Vincenzo; Colombi, Francesco; Bouguerra, Abdellah

    2016-11-01

    The late Miocene (11-9 Ma) volcanic rocks of Kef Hahouner, 40 km NE of Constantine (NE Algeria), are commonly classified as lamproites in literature. However, these rocks are characterized by an anhydrous paragenesis with plagioclase and Mg-rich olivine phenocrysts, set in a groundmass made up of feldspars, pyroxenes and opaque minerals. Thus, we classify the Kef Hahouner rocks as ultrapotassic shoshonites and latites, having K2O > 3 wt.%, K2O/Na2O > 2.5, MgO > 3-4 wt.%, SiO2 < 55-57 wt.% and SiO2/K2O < 15. All the investigated samples show primitive mantle-normalized multi-element patterns typical of orogenic (arc-type) magmas, i.e. enriched in LILE (e.g. Cs, Rb and Ba) and LREE (e.g. La/Yb = 37-59) with respect to the HFSE, peaks at Pb and troughs at Nb and Ta. Initial isotopic ratios are in the range of 87Sr/86Sr = 0.70874-0.70961, 143Nd/144Nd = 0.51222-0.51223, 206Pb/204Pb = 18.54-18.60, 207Pb/204Pb = 15.62-15.70 and 208Pb/204Pb = 38.88-39.16. The Kef Hahouner volcanic rocks show multi-element patterns similar to the other circum-Mediterranean lamproites and extreme Sr, Nd and Pb isotopic compositions. Nevertheless, the abundant plagioclase, the presence of Al-rich augite coupled with high Al2O3 whole rock compositions (9.6-21.4 wt.%), and the absence of phlogopite are all at inconsistent with the definition of lamproite. We reviewed the rocks classified as lamproites worldwide, and found that many of these rocks, as for the Kef Hahouner samples, should be actually defined as "normal" potassic to ultrapotassic volcanic rocks. Even the grouping of lamproites into "orogenic" and "anorogenic" types appears questionable.

  14. Mantle heterogeneities beneath the Northeast Indian Ocean as sampled by intra-plate volcanism at Christmas Island

    NASA Astrophysics Data System (ADS)

    Taneja, Rajat; Rushmer, Tracy; Blichert-Toft, Janne; Turner, Simon; O'Neill, Craig

    2016-10-01

    The intra-plate region of the Northeast Indian Ocean, located between the Ninetyeast Ridge and the North West Shelf of Australia, contains numerous submerged seamounts and two sub-aerially exposed volcanic island groups. While the Cocos (Keeling) Archipelago is a coral atoll, Christmas Island is the only sub-aerially exposed volcanic island and contains Late Cretaceous, Eocene and Pliocene lavas. The lavas are predominantly basaltic in composition, except for one sampled flow that is trachytic. Although the evolution of the western margin of Australia, and the seismicity in the intra-plate region, has received considerable attention, the origin of the seamount province in the Northeast Indian Ocean is still a matter of debate. In order to constrain the origin of volcanism on Christmas Island and the associated Seamount Province we analysed 14 Christmas Island samples for major and trace element abundances and 12 of these for Nd, Hf and Pb isotope compositions. The trace element patterns of the lavas are similar to many ocean island basalts, while high 208Pb/204Pb and 207Pb/204Pb at a given 206Pb/204Pb suggest affiliation with the DUPAL anomaly. The reconstructed position of Christmas Island during the Eocene (44-37 Ma) places the island in close proximity to the (present-day) upper mantle low-seismic velocity anomalies. Moreover, an enriched mantle (EM-2) type component in addition to the DUPAL anomaly is observed in the Eocene volcanic phase. The younger Pliocene ( 4 Ma) sequences at Christmas Island are inferred to be the product of partial melting of existing material induced by lithospheric flexure.

  15. GEMAS: a new view of the lead isotopic soil landscape at the European continental scale

    NASA Astrophysics Data System (ADS)

    Reimann, Clemens; Négrel, Philippe; Flem, Belinda; Fabian, Karl; Birke, Manfred; Ladenberger, Anna; Hoogewerff, Jurian

    2014-05-01

    Soil formation through weathering of bedrock and sediments is an extremely slow process, and soils must be considered an essential and non-renewable resource. Knowledge and extrapolation of threats to soils, e.g., changes in element concentrations and the reasons thereof are of primary importance for society as recently diffuse contamination has been identified as one of the major threats to soil quality. In this frame the addition of isotope tracing at the continental scale is an important supplementary constraint on the origin and behaviour of elements in soils. Lead has been mined and utilized by humans for several thousand years. The accumulated world production is estimated to be over 300 Mt. Detailed studies on environmental samples (e.g., peat bogs, ice cores, sediment cores) suggest a major Pb contamination of the northern hemisphere since ancient times. In spite of its importance the continental scale distribution of lead and lead isotopes combined has never been documented for any geochemical sample material. As the result of a combined effort of the European Geological Surveys, backed by the European metals industry, we present the first continental investigation of Pb concentration and Pb isotope ratios (206Pb,207Pb, 208Pb) landscape using agricultural soil samples (Ap-horizon, 0-20 cm) collected at an average density of 1 site/2500 km2 (2211 samples in total). Thus we here provide the first geochemical reference maps of Pb concentrations combined with Pb isotope ratios at the European scale against which the impact of contamination can be realistically judged. The maps localize the major concentration anomalies of Pb in soils and help to identify the processes that generate the observed distribution patterns. The European continental-scale patterns of Pb concentrations and Pb isotopes show a high variability dominated by geology and influenced by climate. Positive Pb concentration anomalies mark most of the known mineralized areas throughout Europe

  16. Lead (Pb) Isotope Baselines for Studies of Ancient Human Migration and Trade in the Maya Region

    PubMed Central

    Kamenov, George D.; Gilli, Adrian; Hodell, David A.; Emery, Kitty F.; Brenner, Mark; Krigbaum, John

    2016-01-01

    We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica region. We analyzed 60 rock samples for lead isotope ratios and a representative subset of samples for lead, uranium, and thorium concentrations across the Maya region, including the Northern Lowlands of the Mexican Yucatan Peninsula, the Southern Lowlands of Guatemala and Belize, the Volcanic Highlands, the Belizean Maya Mountains, and the Metamorphic Province/Motagua Valley. Although there is some overlap within certain sub-regions, particularly the geologically diverse Metamorphic Province, lead isotopes can be used to distinguish between the Northern Lowlands, the Southern Lowlands, and the Volcanic Highlands. The distinct lead isotope ratios in the sub-regions are related to the geology of the Maya area, exhibiting a general trend in the lowlands of geologically younger rocks in the north to older rocks in the south, and Cenozoic volcanic rocks in the southern highlands. Combined with other sourcing techniques such as strontium (87Sr/86Sr) and oxygen (δ18O), a regional baseline for lead isotope ratios can contribute to the development of lead isoscapes in the Maya area, and may help to distinguish among geographic sub-regions at a finer scale than has been previously possible. These isotope baselines will provide archaeologists with an additional tool to track the origin and movement of ancient humans and artifacts across this important region. PMID:27806065

  17. Mt. St. Augustine, Alaska: Geochemical evolution of an eastern Aleutian volcanic center

    SciTech Connect

    Johnson, K.E. . Dept. of Geology); Harmon, R.S. . Kingsley Dunham Centre); Moorbath, S. . Dept. of Earth Sciences); Sigmarsson, O. )

    1993-04-01

    Mt. St. Augustine is a calc-alkaline Quaternary volcano, situated within Cook Inlet, Alaska. The island is composed of low- to medium-K andesite and dacite domes and pyroclastic flows. Major element variations indicate the magmatic evolution is dominantly influenced by fractionation and magma-mixing processes. Incompatible element and isotopic compositions suggest that despite its continental location, crustal assimilation is not significant factor in magmatic evolution. Alkali contents for Augustine are generally lower than elsewhere in the Aleutians (e.g. Augustine Cs/Rb = 0.016--0.024, K/Rb = 372--553; Aleutians Cs/Rb = 0.016--0.17, K/Rb = 231--745). Sr- and Nd-isotope ratios encompass narrow ranges ([sup 87]Sr/[sup 86]Sr = 0.70317--0.70343; [sup 143]Nd/[sup 144]Nd = 0.513011--0.513085), characteristic of uncontaminated mantle-derived melts. U-Th disequilibrium isotopic values also indicate little or no assimilation of evolved continental crust. Pb-isotopic ranges are also relatively restricted ([sup 206]Pb/[sup 204]Pb = 18.62--18.82; [sup 207]Pb/[sup 204]Pb = 15.54--15.57; [sup 208]Pb/[sup 204]Pb = 38.18--38.34) and comparison with north Pacific enriched (OIB) and depleted (MORB) mantle sources suggest the incorporation of only a small percentage of subducted terrigenous sediments. A model for Augustine magma genesis is proposed where parental magmas are generated by 5--20% partial melting of a lherzolite mantle with up to a 5% subducted terrigenous sediment component. The major influence of the thickened continental crust is to prevent the ascent and eruption of basaltic magma. The data exhibit no temporal variations, indicating that the magmatic system which produced the historic eruptions is well established.

  18. Syn-collisional granitoids in the Qilian Block on the Northern Tibetan Plateau: A long-lasting magmatism since continental collision through slab steepening

    NASA Astrophysics Data System (ADS)

    Huang, Hui; Niu, Yaoling; Mo, Xuanxue

    2016-03-01

    In this paper we present a new model that can explain the large zircon age spectrum of 510 - 420 Ma within a single sample from the Gangcha (Gcha) biotite granodiorite and the Huangyuan (HY) two-mica monzogranite on the northern Tibetan Plateau. The large age spread recorded in zircons is characteristic of granitoid samples from the studied region, which is best explained by the long-lasting magmatism since the onset of continental collision at 500 Ma, followed by slab steepening and the ultimate slab break-off at 450 Ma. These granitoids have a large major and trace element compositional variation, but limited initial Sr (ISr[450] = 0.709 to 0.715), Nd (ԐNd[450] = - 6.5 to - 3.7), Hf (ԐHf[450] = - 4.3 to 1.5) and Pb (206Pb/204Pb[450] = 17.70 to 17.17; 207Pb/204Pb[450] = 15.60 to 15.69; 208Pb/204Pb[450] = 38.04 to 38.73) isotopic variation. The small negative whole rock ԐNd[450] and ԐHf[450] values are most consistent with the granitoid source being dominated by subducted seafloor materials. The inherited zircons with large negative ԐHf[450] values (e.g. - 50) are indicative of input from the lower continental crust and subducted sediments. The correlated variations among major elements, trace elements and radiogenic isotopes are best interpreted as reflecting melting-induced mixing of a compositionally heterogeneous source with superimposed effect of varying extent of fractional crystallization and crustal assimilation. The inherited zircons of Palaeo-Proterozoic age and the Archean crustal model ages signify the involvement of ancient basement rocks.

  19. Oceanic mafic magmatism in the Siletz terrane, NW North America: Fragments of an Eocene oceanic plateau?

    NASA Astrophysics Data System (ADS)

    Phillips, Bethan A.; Kerr, Andrew C.; Mullen, Emily K.; Weis, Dominique

    2017-03-01

    The Siletz terrane, a predominantly mafic accreted oceanic terrane, is located in the Cascadia forearc region of Oregon, Washington and Vancouver Island. The terrane represents a late Palaeocene-Eocene large igneous province that consists of pillow lavas, massive flows and intrusive sheets. Previously it has been proposed that the Siletz terrane represents either an accreted oceanic plateau, hotspot island chain, backarc basin, island arc, or a sequence of slab window volcanics. A province-wide geochemical reassessment of the terrane, including new high precision Sr-Pb-Nd-Hf isotope data, has been used to assess the validity of the proposed tectonomagmatic models for the Siletz terrane. The trace element data show little evidence of crustal contamination, or an arc signature, and the samples have rare earth element (REE) patterns that are flat to light REE enriched. These features are similar to other oceanic plateaus such as the Ontong Java and the Caribbean. Initial isotope ratios range from 206Pb/204 Pb: 18.751 to 19.668, 207Pb/204Pb: 15.507 to 15.661, 208Pb/204Pb: 38.294 to 39.2128, 176Hf/177Hf: 0.28300 to 0.28316 (εHf: 9.0 to 14.5), 143Nd/144Nd: 0.51282 to 0.51299 (εNd: 5.0 to 8.1) and 87Sr/86Sr: 0.70302 to 0.70380. These data are consistent with a mantle source of the Siletz terrane that appears to have been heterogeneous and slightly enriched. The enriched signature has characteristics of both EM2 and HIMU components and this, combined with a calculated mantle potential temperature well above ambient mantle, indicates derivation of the Siletz magmatism from a mantle plume, possibly the Yellowstone Hotspot. We therefore conclude that the Siletz terrane represents an accreted oceanic plateau.

  20. The Permian Dongfanghong island-arc gabbro of the Wandashan Orogen, NE China: Implications for Paleo-Pacific subduction

    NASA Astrophysics Data System (ADS)

    Sun, Ming-Dao; Xu, Yi-Gang; Wilde, Simon A.; Chen, Han-Lin; Yang, Shu-Feng

    2015-09-01

    The Dongfanghong hornblende gabbro is located in the western part of the Wandashan Orogen and to the east of the Jiamusi Block in NE China. It was emplaced into Early Paleozoic oceanic crust (i.e. Dongfanghong ophiolite) at ~ 275 Ma and both later collided with the eastern margin of the Jiamusi Block. The Dongfanghong gabbro is sub-alkaline with high Na2O contents and is characterized by enrichment in light rare earth elements (LREE), large ion lithosphile elements (LILE), Sr, Eu, and Ba, and depletion in high field strength elements (HFSE). The enriched isotopic signatures (87Sr/86Sri = ~ 0.7065, εNd(t) = ~- 0.5, 208Pb/204Pbi = ~ 38.05, 207Pb/204Pbi = ~ 15.56, 206Pb/204Pbi = ~ 18.20 and zircon εHf(t) = ~+ 5.8) indicate an enriched mantle (EM2) source, with some addition of continental material. It has arc geochemical affinities similar to Permian arc igneous rocks in the eastern margin of the Jiamusi Block, the Yakuno Ophiolite in SW Japan, arc rocks along the western margin of the North America Craton, and also the Gympie Group in eastern Australia. All these features, together with information from tectonic discrimination diagrams, suggest that the Dongfanghong gabbro formed in an immature island arc. The spatial configuration of ~ 290 Ma immature continental arc rocks in the eastern part of the Jiamusi Block and the ~ 275 Ma immature island arc Dongfanghong gabbro in the Wandashan Orogen to the east is best explained by eastward arc retreat and slab roll-back of the Paleo-Pacific Plate. This model is also supported by the Carboniferous-Permian stratigraphic transition in the Jiamusi Block from oceanic carbonate rocks to coal-bearing terrestrial clastic rocks and andesites. We thus suggest that both Paleo-Pacific subduction and roll-back occurred in the Early Permian along the eastern margin of Asia.

  1. Lead isotopic studies of the Samail ophiolite, Oman

    SciTech Connect

    Chen, J.H.; Pallister, J.S.

    1981-04-10

    The isotopic composition of Pb and the concentrations of U, Th, and Pb have been determined for samples from various lithologic units and massive sulfides of the Samail ophiolite. The observed /sup 206/Pb//sup 204/Pb ratios range from 17.90 to 19.06, /sup 207/Pb//sup 204/Pb ratios from 15.43 to 15.63, and /sup 208/Pb//sup 204/Pb from 37.66 to 38.78. In Pb isotopic evolution diagrams, the initial Pb isotopic compositions of most of the samples from the Samail ophiolite plot within the field of oceanic basalt, clearly distinct from island arc data, and define some of the least radiogenic Pb observed from oceanic rocks. Lead data from the Samail are compatible with a model involving magma generation from an oceanic mantle source and formation of the ophiolite at an oceanic spreading center. U--Th--Pb isotopic systematics demonstrate that vertical heterogeneity in the oceanic crust can be created through differential concentration of U, Th, and Pb during crystal fractionation and alteration at, or near, the spreading ridge. Calcite form amygdules in the ophiolite basalt has similar Pb isotopic composition to the igneous rocks, suggesting precipitation of the calcite from seawater which contained Pb derived mostly from the oceanic crust. Lead isotopic data on Fe--Cu sulfides are also similar to the results from the igneous suite suggesting that the source of the sulfides is predominently from the oceanic crust. Lead data from serpentinized peridotite and a galena sample from below the ophiolite suggest that part of the serpentinization process and the formation of galena could involve addition of radiogenic Pb from either a continental source or from oceanic sediments.

  2. Sr-Nd-Pb-Hf isotope systematics of the Hugo Dummett Cu-Au porphyry deposit (Oyu Tolgoi, Mongolia)

    NASA Astrophysics Data System (ADS)

    Dolgopolova, A.; Seltmann, R.; Armstrong, R.; Belousova, E.; Pankhurst, R. J.; Kavalieris, I.

    2013-04-01

    Major and trace element geochemistry including Sr-Nd-Pb-Hf isotopic data are presented for a representative sample suite of Late Devonian to Early Carboniferous plutonic and volcanic rocks from the Hugo Dummett deposit of the giant Oyu Tolgoi porphyry Cu-Au district in South Gobi, Mongolia. Sr and Nd isotopes (whole-rock) show restricted ranges of initial compositions, with positive ɛNdt mainly between + 3.4 and + 7.4 and (87Sr/86Sr)t predominantly between 0.7037 and 0.7045 reflecting magma generation from a relatively uniform juvenile lithophile-element depleted source. Previously dated zircons from the plutonic rocks exhibit a sample-averaged range of ɛHft values of + 11.6 to + 14.5. Depleted-mantle model ages of 420-830 (Nd) and 320-730 Ma (zircon Hf) limit the involvement of pre-Neoproterozoic crust in the petrogenesis of the intermediate to felsic calc-alkaline magmas to, at most, a minor role. Pb isotopes (whole-rock) show a narrow range of unradiogenic initial compositions: 206Pb/204Pb 17.40-17.94, 207Pb/204Pb 15.43-15.49 and 208Pb/204Pb 37.25-37.64, in agreement with Sr-Nd-Hf isotopes indicating the dominance of a mantle component. All four isotopic systems suggest that the magmas from which the large Oyu Tolgoi porphyry system was generated originated predominantly from juvenile material within the subduction-related setting of the Gurvansayhan terrane.

  3. Petrogenesis and geodynamics of plagiogranites from Central Turkey (Ekecikdağ/Aksaray): new geochemical and isotopic data for generation in an arc basin system within the northern branch of Neotethys

    NASA Astrophysics Data System (ADS)

    Köksal, Serhat; Toksoy-Köksal, Fatma; Göncüoglu, M. Cemal

    2016-09-01

    In the Late Cretaceous, throughout the closure of the Neotethys Ocean, ophiolitic rocks from the İzmir-Ankara-Erzincan ocean branch were overthrusted the northern margin of the Tauride-Anatolide Platform. The ophiolitic rocks in the Ekecikdaǧ (Aksaray/Central Turkey) region typify the oceanic crust of the İzmir-Ankara-Erzincan branch of Neotethys. The gabbros in the area are cut by copious plagiogranite dykes, and both rock units are intruded by mafic dykes. The plagiogranites are leucocratic, fine- to medium-grained calc-alkaline rocks characterized mainly by plagioclase and quartz, with minor amounts of biotite, hornblende and clinopyroxene, and accessory phases of zircon, titanite, apatite and opaque minerals. They are tonalite and trondhjemite in composition with high SiO2 (69.9-75.9 wt%) and exceptionally low K2O (<0.5 wt%) contents. The plagiogranites in common with gabbros and mafic dykes show high large-ion lithophile elements/high-field strength element ratios with depletion in Nb, Ti and light rare-earth elements with respect to N-MORB. The plagiogranites together with gabbros and mafic dykes show low initial 87Sr/86Sr ratios (0.70419-0.70647), high ƐNd(T) (6.0-7.5) values with 206Pb/204Pb (18.199-18.581), 207Pb/204Pb (15.571-15.639) and 208Pb/204Pb (38.292-38.605) ratios indicating a depleted mantle source modified with a subduction component. They show similar isotopic characteristics to the other supra-subduction zone (SSZ) ophiolites in the Eastern Mediterranean to East Anatolian-Lesser Caucasus and Iran regions. It is suggested that the Ekecikdaǧ plagiogranite was generated in a short time interval from a depleted mantle source in a SSZ/fore-arc basin setting, and its nature was further modified by a subduction component during intra-oceanic subduction.

  4. Mesozoic igneous intrusions in New England and Quebec: Implications from lead (Pb) isotopes on petrogenesis and mantle sources (Ascutney Mountain, Vermont; Mont Saint Hilaire, Quebec; Pliny Complex, New Hampshire)

    SciTech Connect

    Schucker, D.E.

    1992-01-01

    Lead isotopes are used to study Mesozoic intrusions from New England and Quebec, specifically the igneous complexes of Ascutney Mountain (Vermont), Mont Saint Hilaire (Quebec), and Pliny (New Hampshire). The main objectives are to address the: (1) petrogenesis of specific complexes using Pb isotopes along with previous results; and (2) sources of parental magmas in the context of a possible plume source for the Cretaceous intrusions and New England Seamounts. Analytical procedures for Pb and U are also described in detail. For each of the three complexes, significant variation in apparent initial [sup 208]Pb/[sup 204]Pb, [sup 207]Pb/[sup 204]Pb, and [sup 206]Pb/[sup 204]Pb ratios are observed. These variations reflect crustal contamination and local country rocks are isotopically suitable contaminants. Contamination lowers the Pb isotopic ratios of the modified magmas. The Pb ratios of the parental magmas are constrained by defining trends resulting from crustal contamination. At the Ascutney complex, granites appear to be uniform at the time of formation based on feldspar results. Granite whole rocks exhibit open system U-Pb behavior which is attributed to significant recent U loss (of up to 38%). Both local schists and gneisses are important contaminants with generally <25% contamination. Significant isotopic variations are apparent at Mont Saint Hilaire where rock-feldspar variations are apparently not in isotopic equilibrium. Feldspars reflect magmatic values and indicate crustal contamination of a parental magma for the Hilaire complex. A limited data set for the Pliny complex suggests a parental magma. The Pb results support a common mantle source for the Cretaceous continental intrusions (Ascutney and Mont Saint Hilaire) and the New England Seamounts. They imply magma from a sublithospheric mantle-plume, and that magmas ascended with little or no lithospheric interaction. The magma source for the Jurassic Pliny complex appears to be different.

  5. Lead (Pb) Isotope Baselines for Studies of Ancient Human Migration and Trade in the Maya Region.

    PubMed

    Sharpe, Ashley E; Kamenov, George D; Gilli, Adrian; Hodell, David A; Emery, Kitty F; Brenner, Mark; Krigbaum, John

    2016-01-01

    We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica region. We analyzed 60 rock samples for lead isotope ratios and a representative subset of samples for lead, uranium, and thorium concentrations across the Maya region, including the Northern Lowlands of the Mexican Yucatan Peninsula, the Southern Lowlands of Guatemala and Belize, the Volcanic Highlands, the Belizean Maya Mountains, and the Metamorphic Province/Motagua Valley. Although there is some overlap within certain sub-regions, particularly the geologically diverse Metamorphic Province, lead isotopes can be used to distinguish between the Northern Lowlands, the Southern Lowlands, and the Volcanic Highlands. The distinct lead isotope ratios in the sub-regions are related to the geology of the Maya area, exhibiting a general trend in the lowlands of geologically younger rocks in the north to older rocks in the south, and Cenozoic volcanic rocks in the southern highlands. Combined with other sourcing techniques such as strontium (87Sr/86Sr) and oxygen (δ18O), a regional baseline for lead isotope ratios can contribute to the development of lead isoscapes in the Maya area, and may help to distinguish among geographic sub-regions at a finer scale than has been previously possible. These isotope baselines will provide archaeologists with an additional tool to track the origin and movement of ancient humans and artifacts across this important region.

  6. Determination of Cd, Cr, Hg and Pb in plastics from waste electrical and electronic equipment by inductively coupled plasma mass spectrometry with collision-reaction interface technology.

    PubMed

    Santos, Mirian C; Nóbrega, Joaquim A; Cadore, Solange

    2011-06-15

    A procedure based on the use of a quadrupole inductively coupled plasma-mass spectrometer equipped with a collision-reaction interface (CRI) for control of spectral overlap interferences was developed for simultaneous determination of Cd, Cr, Hg, and Pb in plastics from waste electrical and electronic equipment (WEEE). The injection of H(2) and He (80 and 60 mL min(-1), respectively) into the sampled plasma, colliding and reacting with potentially interfering polyatomic ions, allows interference-free determination of chromium via its isotopes (52)Cr and (53)Cr that are freed from overlap due to the occurrence of (40)Ar(12)C(+), (40)Ar(12)C(1)H(+), (36)S(16)O(+) or (1)H(36)S(16)O(+). Cadmium, Hg and Pb were directly determined via their isotopes (110)Cd, (111)Cd, (112)Cd, (199)Hg, (200)Hg, (201)Hg, (202)Hg, (206)Pb, (207)Pb, and (208)Pb, without using CRI. The CRI can be quickly activated or deactivated before each analyte measurement. Limits of detection for (52)Cr were 0.04 or 0.14 μg L(-1) with He or H(2) injected in CRI. Cadmium and Pb have LODs between 0.02 and 0.08 μg L(-1) and Hg had 0.93-0.98 μg L(-1), without using CRI. Analyte concentrations for samples varied from 16 to 43, 1 to 11, 4 to 12, and 5 to 13 mg kg(-1) for Cr, Cd, Hg and Pb, respectively.

  7. Early Cretaceous (ca. 100 Ma) magmatism in the southern Qiangtang subterrane, central Tibet: Product of slab break-off?

    NASA Astrophysics Data System (ADS)

    Li, Yalin; He, Haiyang; Wang, Chengshan; Wei, Yushuai; Chen, Xi; He, Juan; Ning, Zijie; Zhou, Aorigele

    2016-09-01

    The lack of Early Cretaceous magmatic records with high-quality geochemical data in the southern Qiangtang subterrane has inhibited a complete understanding of the magmatic processes and geological evolution of central Tibet. In this study, we present zircon U-Pb ages, whole-rock geochemistry, and Sr-Nd-Pb and zircon Hf isotopic data for the newly discovered Moku pluton in the southern Qiangtang subterrane. Zircon U-Pb dating reveals that the Moku granites were emplaced in the Early Cretaceous (ca. 100 Ma) and are coeval with the hosted dioritic enclaves. The granites are slightly peraluminous and high-K calc-alkaline I-type granites and characterized by initial (87Sr/86Sr)i ratios of 0.70605-0.70658, negative ɛ Nd(t) values (-4.44 to -3.35), and Nd isotopic model ages of 1.19-1.29 Ga. The granites have a wide range of zircon ɛ Hf(t) values (-24.4 to 2.6) and concordant ratios of (206Pb/204Pb)t = 18.645-18.711, (207Pb/204Pb)t = 15.656-15.666, and (208Pb/204Pb)t = 38.751-38.836. The coeval dioritic enclaves are medium- to high-K calc-alkaline rocks with zircon ɛ Hf(t) values of -13.3 to +3.6. The geochemical signatures of the host granites and coeval dioritic enclaves indicate that the Moku pluton was most likely generated by partial melting of the ancient lower crust with contributions from mantle-derived melts. Our new data, together with other recently published data, indicate that the ca. 100 Ma magmatic rocks were derived from anatexis of the Qiangtang lower crust that mixed with upwelling asthenosphere materials in response to the slab break-off of the northward subduction of the Bangong-Nujiang oceanic lithosphere.

  8. Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: a freshwater bivalve study.

    PubMed

    Company, R; Serafim, A; Lopes, B; Cravo, A; Shepherd, T J; Pearson, G; Bebianno, M J

    2008-11-01

    Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, delta-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)/Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance.

  9. A proposed new approach and unified solution to old Pb paradoxes

    NASA Astrophysics Data System (ADS)

    Castillo, Paterno R.

    2016-05-01

    One of the most remarkable features of many and, perhaps, all oceanic basalts is that their Pb isotopic ratios (206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) are too radiogenic to be coming from the undifferentiated mantle or bulk silicate Earth. This has created three major concerns in the behavior of U, Th and Pb in the Earth's mantle that have been termed the Pb paradoxes. These are the unexpectedly long time-integrated high U/Pb (1st paradox), long time-integrated low Th/U (2nd paradox) and constant Ce/Pb and Nb/U (3rd paradox) in the mantle sources of oceanic basalts. The origins of such unexpected ratios have been the object of intense studies that produced several highly significant, but generally individualized results during the last four decades. Detailed analysis of available data shows that the paradoxes are closely interrelated as they all pertain to the mantle and have many common characteristic features. Thus, the Pb paradoxes constitute a system of equations that must be solved all together as each solution must satisfy every equation in the system. For example, compositional data for the voluminous mid-ocean ridge basalts (MORB) show that the 1st and 2nd paradoxes exhibit a long time-integrated enrichment of U and the Th/U and Nb/Th ratios are also constant. A single solution to simultaneously explain the paradoxes in MORB is possible if recycled materials with variable enrichments in incompatible trace elements, particularly U and its daughter Pb* plus Nb, Ce, and Th are added to or mixed with the depleted upper mantle. Significantly, a similar binary mixing solution has been proposed for the Pb paradoxes in ocean island basalts.

  10. Binary mixing of enriched and undegassed (primitive?) mantle components (He, Sr, Nd, Pb) in Samoan lavas

    NASA Astrophysics Data System (ADS)

    Farley, K. A.; Natland, J. H.; Craig, H.

    1992-06-01

    We have measured He, Sr, Nd, and Pb isotope ratios and Rb, Sr, Sm, and Nd concentrations in stratigraphically controlled lavas from the Pago shield volcano on Tutuila, American Samoa. We interpret these lavas as products of mixing between two isotopically extreme mantle constituents. The first is a highly enriched component with very high Sr isotope ratios, low 3He/ 4He ratios, and high "Δ(74)" and "Δ(84)" Pb isotopic characteristics. This is probably recently recycled ( < 400 Ma) crustal material. The second component has high 3He/ 4He ratios ( > 24R A) and intermediate Sr, Nd, and Pb isotopic ratios. This material was derived from a largely undegassed mantle source, and, in conjunction with data from several other ocean islands, provides strong evidence for the existence of a high 3He/ 4He ratio mantle end member (primitive helium mantle, PHEM) with consistent Sr, Nd, and Pb isotopic characteristics: near bulk-earth 87Sr/ 86Sr (0.7042-0.7052) and 143Nd/ 144Nd (0.51265-0.51280,ɛ Nd = +0.2to+3.2), and radiogenic Pb ( 206Pb/ 204Pb˜ 18.5-19.0, 207Pb/ 204Pb˜ 15.5-15.57, 208Pb/ 204Pb˜ 38.4-39.2). Although this material cannot have been derived from a reservoir completely closed to elemental fractionation for the full 4.55 Ga duration of Earth's history, it may indicate the presence of a highly primitive mantle source. Erratic temporal variations in the isotopic composition of individual flows indicate sporadic and variable mixing of these two sources. We interpret these results using a model in which high 3He/ 4He ratio plume material, rising intermittently from a lower-mantle source, intercepts and melts recycled crustal matter in the upper mantle or lithosphere and erupts as a binary mixture of PHEM and the so-called "EM" components derived from this recycled material.

  11. The origin of lead in the organic horizon of tundra soils: atmospheric deposition, plant translocation from the mineral soil or soil mineral mixing?

    PubMed

    Klaminder, Jonatan; Farmer, John G; MacKenzie, Angus B

    2011-09-15

    Knowledge of the anthropogenic contribution to lead (Pb) concentrations in surface soils in high latitude ecosystems is central to our understanding of the extent of atmospheric Pb contamination. In this study, we reconstructed fallout of Pb at a remote sub-arctic region by using two ombrotrophic peat cores and assessed the extent to which this airborne Pb is able to explain the isotopic composition ((206)Pb/(207)Pb ratio) in the O-horizon of tundra soils. In the peat cores, long-range atmospheric fallout appeared to be the main source of Pb as indicated by temporal trends that followed the known European pollution history, i.e. accelerated fallout at the onset of industrialization and peak fallout around the 1960s-70s. The Pb isotopic composition of the O-horizon of podzolic tundra soil ((206)Pb/(207)Pb=1.170 ± 0.002; mean ± SD) overlapped with that of the peat ((206)Pb/(207)Pb=1.16 ± 0.01) representing a proxy for atmospheric aerosols, but was clearly different from that of the parent soil material ((206)Pb/(207)Pb=1.22-1.30). This finding indicated that long-range fallout of atmospheric Pb is the main driver of Pb accumulation in podzolic tundra soil. In O-horizons of tundra soil weakly affected by cryoturbation (cryosols) however, the input of Pb from the underlying mineral soil increased as indicated by (206)Pb/(207)Pb ratios of up to 1.20, a value closer to that of local soil minerals. Nevertheless, atmospheric Pb appeared to be the dominant source in this soil compartment. We conclude that Pb concentrations in the O-horizon of studied tundra soils - despite being much lower than in boreal soils and representative for one of the least exposed sites to atmospheric Pb contaminants in Europe - are mainly controlled by atmospheric inputs from distant anthropogenic sources.

  12. Assessment of pollution aerosols sources above the Straits of Dover using lead isotope geochemistry.

    PubMed

    Deboudt, K; Flament, P; Weis, D; Mennessier, J P; Maquinghen, P

    1999-09-15

    We assess the capability of lead isotopes to study the transport of pollution aerosols above the Straits of Dover by collecting atmospheric aerosols above the Eastern Channel and the Southern Bight of the North Sea. During the same period, we characterized the lead isotopic signature of the main industrial sources on the French coast near the Straits of Dover. Urban and automobile-derived aerosols were also collected. Due to the phasing out of lead in gasoline, the urban isotopic composition (206Pb/207Pb = 1.158 +/- 0.003) has become more radiogenic, although it is highly variable. On a regional scale, major industrial emissions have a well-defined isotopic composition (1.13 < 206Pb/207Pb < 1.22), more radiogenic than the petrol-lead signature (1.06 < 206Pb/207Pb < 1.12). These results together with those measured near the main coastal highway show that the automobile source has become a minor component of particulate lead in air. On a local scale, Dunkerque, the most urbanized and industrialized area along the Straits of Dover, may transiently control elevated lead concentrations. Except for the occurrence of local and regional range transport episodes, lead concentrations in the Straits of Dover can be related to remote or semi-remote pollution source emissions. Combining air mass retrospective trajectories and related lead abundances and isotopic compositions, it can be shown that lead aerosols originating from eastern Europe have an isotopic signature (1.145 < 206Pb/207Pb < 1.169) different from the isotopic composition of west-European lead aerosols (1.111 < 206Pb/207Pb < 1.142). The influence of remote North American sources is suggested, with caution, due to uncertainties in meteorological calculations.

  13. A lead isotopic study of the Stillwater Complex, Montana: constraints on crustal contamination and source regions

    USGS Publications Warehouse

    Wooden, J.L.; Czamanske, G.K.; Zientek, M.L.

    1991-01-01

    Analyses of the Pb isotopic compositions of plagioclase from 23 samples covering the stratigraphic thickness of the Stillwater Complex indicate a narrow range of apparent initial isotopic compositions (206Pb/ 204Pb=13.95; 207Pb/204Pb=14.95-15.01; 208Pb/204Pb=33.6). The uniformity of our data is in contrast to, but not necessarily contradictory to, other recent investigations which give indications that the complex formed by repeated injection of magmas with at least two distinct compositions that were presumably derived from different source regions. Samples from the Basal series of the complex have consistently higher 207Pb/204Pb ratios, suggesting either minor contamination from adjacent country rocks or a slight distinction between parental magmas. Apparent initial Pb isotopic compositions of the complex are very radiogenic compared to Late Archean model-mantle values, but are nearly identical to initial Pb isotopic compositions found for the the adjacent, slightly older (2.73-2.79 Ga), Late Archean crustal suite in the Beartooth Mountains. Contamination of magmas parental to the Stillwater Complex by the Late Archean crustal suite is rejected for two reasons: (1) Th and U concentrations in Stillwater rocks and plagioclase are very low (about 0.08 and 0.02 ppm respectively), yet Th/U ratios are uniform at about 4, in contrast to the highly variable (2-26) but often high Th/U ratios found for the Late Archean crustal complex; (2) it seems improbable that any contamination process would have adjusted the isotopic compositions of the diverse magmas entering the Stillwater chamber to near-identical values. The preferred hypothesis to explain the Pb isotopic data for the Stillwater Complex and the associated Late Archean crustal suite involves a major Late Archean crust-forming event that resulted in a compositionally complex crust/mantle system with relatively homogeneous and unusual Pb isotopic compositions. The parental magmas of the Stillwater Complex were

  14. Shifts in alpine lakes' ecosystems in Japan driven by increasing Asian dusts

    NASA Astrophysics Data System (ADS)

    Tsugeki, N. K.; Tani, Y.; Ueda, S.; Agusa, T.; Toyoda, K.; Kuwae, M.; Oda, H.; Tanabe, S.; Urabe, J.

    2011-12-01

    Recently in East Asia the amount of fossil fuel combustion have increased with economic growth. It has caused a problem of trans-boundary air pollution in the whole of eastern Asia. Furthermore, Asian dust storms contribute episodically to the global aerosol load. However, the effects of increased Asian dusts on aquatic ecosystems are not well understood. If biologically important nutrients such as nitrogen (N) and phosphorus (P) are transported via air dust, the atmospheric deposition of the dust may have serious impacts on recipient aquatic ecosystems because the biological production is limited by these nutrient elements. A previous report using sedimentary records has evaluated that atmospheric P inputs to the alpine lakes in the United States increased fivefold following the increased western settlement to this country during the nineteenth century. Since P is the most deficient nutrient for production in many lakes increase in P loading through atmospheric deposition of anthropogenically-derived dust might greatly affect the lake ecosystems. We examined fossil pigments and zooplankton remains from Pb-dated sediments taken from a high mountain lake of Hourai-Numa, located in the Towada-Hachimantai National Park of Japan, to uncover historical changes in the phyto- and zooplankton community over the past 100 years. Simultaneously, we measured the biogeochemical variables of TOC, TN, TP, δ13C, δ15N, and 206Pb/207Pb, 208Pb/207Pb in the sediments to identify environmental factors causing such changes. As a result, despite little anthropogenic activities in the watersheds, alpine lakes in Japan Islands increased algal and herbivore plankton biomasses by 3-6 folds for recent years depending on terrestrial the surrounded vegetations and landscape conditions. Biological and biogeochemical proxies recorded in the lake sediments indicate that this eutrophication occurred after the 1990s when P deposition increased due to atmospheric loading transported from Asian

  15. Pb-Sr isotopic and geochemical constraints on sources and processes of lead contamination in well waters and soil from former fruit orchards, Pennsylvania, USA: A legacy of anthropogenic activities

    USGS Publications Warehouse

    Ayuso, Robert A.; Foley, Nora K.

    2016-01-01

    Isotopic discrimination can be an effective tool in establishing a direct link between sources of Pb contamination and the presence of anomalously high concentrations of Pb in waters, soils, and organisms. Residential wells supplying water containing up to 1600 ppb Pb to houses built on the former Mohr orchards commercial site, near Allentown, PA, were evaluated to discern anthropogenic from geogenic sources. Pb (n = 144) and Sr (n = 40) isotopic data and REE (n = 29) data were determined for waters from residential wells, test wells (drilled for this study), and surface waters from pond and creeks. Local soils, sediments, bedrock, Zn-Pb mineralization and coal were also analyzed (n = 94), together with locally used Pb-As pesticide (n = 5). Waters from residential and test wells show overlapping values of 206Pb/207Pb, 208Pb/207Pb and 87Sr/86Sr. Larger negative Ce anomalies (Ce/Ce*) distinguish residential wells from test wells. Results show that residential and test well waters, sediments from residential water filters in water tanks, and surface waters display broad linear trends in Pb isotope plots. Pb isotope data for soils, bedrock, and pesticides have contrasting ranges and overlapping trends. Contributions of Pb from soils to residential well waters are limited and implicated primarily in wells having shallow water-bearing zones and carrying high sediment contents. Pb isotope data for residential wells, test wells, and surface waters show substantial overlap with Pb data reflecting anthropogenic actions (e.g., burning fossil fuels, industrial and urban processing activities). Limited contributions of Pb from bedrock, soils, and pesticides are evident. High Pb concentrations in the residential waters are likely related to sediment build up in residential water tanks. Redox reactions, triggered by influx of groundwater via wells into the residential water systems and leading to subtle changes in pH, are implicated in precipitation of Fe oxyhydroxides

  16. Childhood lead poisoning from the smelter in Torreon, Mexico

    SciTech Connect

    Soto-Jimenez, Martin F.; Flegal, Arthur R.

    2011-05-15

    Lead concentrations and isotopic compositions in blood samples of 34 children (ages 2-17 years) living within a 113 km{sup 2} area of a silver-zinc-lead smelter plant in Torreon, Mexico were compared to those of associated environmental samples (soil, aerosols, and outdoor and indoor dust) to identify the principal source(s) of environmental and human lead contamination in the area. Lead concentrations of soil and outdoor dust ranged 130-12,050 and 150-14,365 {mu}g g{sup -1}, respectively. Concentrations were greatest near the smelter, with the highest levels corresponding with the prevailing wind direction, and orders of magnitude above background concentrations of 7.3-33.3 {mu}g g{sup -1}. Atmospheric lead depositions in the city varied between 130 and 1350 {mu}g m{sup -2} d{sup -1}, again with highest rates <1 km from the smelter. Blood lead (PbB) concentrations (11.0{+-}5.3 {mu}g dl{sup -1}) levels in the children ranged 5.0-25.8 {mu}g dl{sup -1}, which is 3-14 times higher than the current average (1.9 {mu}g dl{sup -1}) of children (ages 1-5 years) in the US. Lead isotopic ratios ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 207}Pb) of the urban dust and soil (1.200{+-}0.009, 2.467{+-}0.003), aerosols (1.200{+-}0.002, 2.466{+-}0.002), and PbB (1.199{+-}0.001, 2.468{+-}0.002) were indistinguishable from each other, as well as those of the lead ores processed at the smelter (1.199{+-}0.007, 2.473{+-}0.007). Consequently, an elevated PbB concentrations of the children in Torreon, as well as in their environment, are still dominated by industrial emissions from the smelter located within the city, in spite of new controls on atmospheric releases from the facility. - Highlights: {yields} Pb contents in environmental samples evidenced chronic Pb pollution in Torreon. {yields} Pb stable isotopes evidenced contemporary emissions from the Ag-Cod-Pb-Zn smelter. {yields} Pb urban dust and soil account for most of the childhood lead poisoning in Torreon.{yields} Levels of

  17. Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health

    SciTech Connect

    Taylor, Mark Patrick Mould, Simon Anthony; Kristensen, Louise Jane; Rouillon, Marek

    2014-11-15

    Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10 μg/dL in children aged 1–4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450 mg/kg) and zinc (mean 3,710 mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500 μg/m{sup 2}) with the highest lead in surface dust (59,900 μg/m{sup 2}) and post-play hand wipes (60,900 μg/m{sup 2}) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 207}Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children. - Highlights: 1.Playground soils and surface dust in a mining town have high metal concentrations. 2.Elevated levels of As, Cd, Pb and Zn dust are found on playground users′ hands. 3.Pb isotope analysis shows that the source of playground dust is ore body Pb. 4.Surface mine operations must be contained to reduce childhood lead exposure risks. 5.Mine environmental licences need to set trigger values for As, Cd, Pb and Zn dust.

  18. Childhood lead poisoning from the smelter in Torreón, México.

    PubMed

    Soto-Jiménez, Martin F; Flegal, Arthur R

    2011-05-01

    Lead concentrations and isotopic compositions in blood samples of 34 children (ages 2-17 years) living within a 113 km(2) area of a silver-zinc-lead smelter plant in Torreón, México were compared to those of associated environmental samples (soil, aerosols, and outdoor and indoor dust) to identify the principal source(s) of environmental and human lead contamination in the area. Lead concentrations of soil and outdoor dust ranged 130-12,050 and 150-14,365 μg g(-1), respectively. Concentrations were greatest near the smelter, with the highest levels corresponding with the prevailing wind direction, and orders of magnitude above background concentrations of 7.3-33.3 μg g(-1). Atmospheric lead depositions in the city varied between 130 and 1350 μg m(-2) d(-1), again with highest rates <1 km from the smelter. Blood lead (PbB) concentrations (11.0±5.3 μg dl(-1)) levels in the children ranged 5.0-25.8 μg dl(-1), which is 3-14 times higher than the current average (1.9 μg dl(-1)) of children (ages 1-5 years) in the US. Lead isotopic ratios ((206)Pb/(207)Pb, (208)Pb/(207)Pb) of the urban dust and soil (1.200±0.009, 2.467±0.003), aerosols (1.200±0.002, 2.466±0.002), and PbB (1.199±0.001, 2.468±0.002) were indistinguishable from each other, as well as those of the lead ores processed at the smelter (1.199±0.007, 2.473±0.007). Consequently, an elevated PbB concentrations of the children in Torreón, as well as in their environment, are still dominated by industrial emissions from the smelter located within the city, in spite of new controls on atmospheric releases from the facility.

  19. Late Eocene-Early Oligocene two-mica granites in NW Turkey (the Uludağ Massif): Water-fluxed melting products of a mafic metagreywacke

    NASA Astrophysics Data System (ADS)

    Topuz, Gültekin; Okay, Aral I.

    2017-01-01

    This paper deals with the petrogenesis of two-mica granites within the amphibolite-facies metamorphic rocks in the Uludağ Massif (NW Turkey). The two-mica granites are represented by three different types (i) a 17 km long and 1.5 km-wide strongly foliated and lineated metagranite, (ii) a relatively younger circular granite, 11 km by 6.5 km, free of any penetrative fabric, and (iii) up to 5 m thick dikes of unfoliated granite-porphyries. Mineral constituents include quartz, plagioclase, microcline, biotite, muscovite and minor apatite, zircon, ilmenite and monazite. U-Pb zircon dating indicates that the metagranite was emplaced at 35 ± 1 Ma (2σ, latest Eocene) and the unfoliated granite at 28 ± 1 Ma (2σ) (Early-Late Oligocene boundary). Overall, the two-mica granites are characterized by (i) a restricted bulk composition (SiO2 70-76 wt.%), (ii) near-linear to linear inter-element variations, (iii) high concentrations of Al2O3, Sr, Ba, LREEs, and low abundances of Rb, Y, Sc and HREEs, comparable with adakitic rocks, (iv) variably pronounced concave-upward shape of HREEs and absent to feeble Eu anomaly, (v) relatively high Na2O, CaO and Sr, and lower K2O and Rb contents at identical silica contents relative to the classical S-type granites. 87Sr/86Sr(i) and εNd(i) values range from 0.7052 to 0.7080, and 0.7 to - 3.6, respectively. The 206Pb/204Pb(i) values range from 18.23 to 18.69, 207Pb/204Pb(i) from 15.63 to 15.70 and 208Pb/204Pb(i) from 38.48 to 38.77. 87Sr/86Sr(i) and εNd(i), and εNd(i) and 207Pb/204Pb(i) values are negatively correlated. Isotopic variation and negative correlations can best be explained by a heterogeneous source, including an older crustal component and a more juvenile basic component. Magma temperatures are estimated as 754-790 °C based on zircon and monazite saturation. All these features such as (i) relatively Na-, Ca- and Sr-rich compositions, (ii) isotopically heterogeneous source with inferred residual phases such as garnet and

  20. Factors controlling elevated lead concentrations in water samples from aquifer systems in Florida

    USGS Publications Warehouse

    Katz, B.G.; Bullen, M.P.; Bullen, T.D.; Hansard, Paul

    1999-01-01

    Concentrations of total lead (Pb) and dissolved Pb exceeded the U.S. Environmental Protection Agency action level of 15 micrograms per liter (mg/L) in approximately 19 percent and 1.3 percent, respectively, of ground-water samples collected during 1991-96 from a statewide network of monitoring wells designed to delineate background water quality of Florida's major aquifer systems. Differences in total Pb concentrations among aquifer systems reflect the combined influence of anthropogenic sources and chemical conditions in each system. A highly significant (p<0.001) difference in median total Pb concentrations was found for water samples from wells with water-level recording devices that contain Pb-counterweights (14 mg/L) compared to non-recorder wells (2 mg/L). Differences between total Pb concentrations for recorder and non-recorder wells are even more pronounced when compared for each aquifer system. The largest differences for recorder status are found for the surficial aquifer system, where median total Pb concentrations are 44 and 2.4 mg/L for recorder wells and non-recorder wells, respectively. Leaching of Pb from metal casing materials is another potential source of Pb in ground water samples. Median total Pb concentrations in water samples from the surficial, intermediate, and Floridan aquifer systems are higher from recorder wells cased with black iron than for recorder wells with steel and PVC casing material. Stable isotopes of Pb were used in this study to distinguish between anthropogenic and natural sources of Pb in ground water, as Pb retains the isotopic signature of the source from which it is derived. Based on similarities between slopes and intercepts of trend lines for various sample types (plots of 206Pb/204Pb versus 208Pb/204Pb and 207Pb/204Pb versus 208Pb/204Pb) the predominant source of total Pb in water samples from the surficial aquifer system is corrosion of Pb counterweights. It is likely that only ground-water samples, not the aquifer

  1. N zooming into the Mediterranean outflow fossil moat during the 1.2-1.8 million years period (Early-Pleistocene) - An approach by radiogenic and stable isotopes

    NASA Astrophysics Data System (ADS)

    Lebreiro, Susana M.; Antón, Laura; Reguera, M. Isabel; Fernández, Marta; Conde, Estefanía; Barrado, Ana I.; Yllera, Abel

    2015-12-01

    The fossil Alvarez Cabral erosive Moat contains hemipelagite, contourite and turbidite facies where oceanography changes in the Mediterranean outflow are archived over the 1.2-1.8 Myr time period. Here we used Pb and Sr radiogenic isotopes to trace water masses and sediment source changes, for the first time in twenty glacial-interglacial (G-I) cycles of the Early-Pleistocene interval, and the last Glacial Maximum through Holocene cycle (including the Younger Dryas and Heinrich Stadial-1). A mixing line of Pb isotopes gives reliable low radiogenic 208Pb/204Pb, 206Pb/204Pb, and 206Pb/207Pb typical of Mediterranean Outflow Water (MOW) in one end-member and the signature of high radiogenic isotopes of Atlantic Waters (AW) towards the second end-member. The 87Sr/86Sr isotopes also display two end-members of the mixing line between eolian transport/dust source (0.71) and fluvial transport/weathering source (0.73) previously proposed in the Gulf of Cadiz. Combination of Pb and Sr radiogenic isotopes with O and C stable isotopes of planktonic and benthic foraminifera, and the response of foraminifera benthos over the Early-Pleistocene interval, reveals a direct link between water masses circulation and shifts in G-I. We found a persistent cyclic pattern of MOW circulation and fluvial deposition during glaciations and AW and aeolian influence during interglaciations. On site U1386B/C, the upper-MOW was less ventilated but productive and with high flux of organic flux matter during glacials, while Atlantic Waters were better ventilated, enriched in O, but less productive during interglacials. We infer that shifts in ocean and atmospheric processes in the Gulf of Cadiz were strongly controlled by Earth's obliquity (41 kyr-cycle) and 35°NH insolation during the Early-Pleistocene. We propose a correlation in changes in phase-relationship between precession and obliquity. In general terms, physical properties of fine sediments (glacials) show lower NGR, low reflectance and

  2. Historical lead isotope record of a sediment core from the Derwent River (Tasmania, Australia): a multiple source environment.

    PubMed

    Townsend, Ashley T; Seen, Andrew J

    2012-05-01

    A 105 cm sediment core from the Derwent River (Tasmania, Australia) was collected in 2004 and was characterised considering both physical (loss on ignition at 550 °C and grain size) and chemical (Fe, Cu, Zn, Cd and Pb concentrations, Pb isotope ratios and (210)Pb dating) properties. The core was analysed to (i) investigate the historical profiles of some important elements associated with the Risdon zinc refinery adjacent to the Derwent River, (ii) determine Pb isotopic signatures of sediment samples, and (iii) assess the veracity of Pb isotope ratios as indicators of contaminant Pb input. Extractable metal concentrations were (all values as mgkg(-1), non-normalised for grain size) Fe: 20,000-35,000, Zn: 42-4500, Pb: 5-1090, Cu: 13-141, and Cd: 1-31; with a close correlation between Cu, Zn, Cd and Pb. Metal enrichment factors (normalised to Al) were Pb: 0.9-144, Zn: 0.8-93, Cd: 0.8-30, Cu: 0.8-8.9 and Fe: 0.9-1.3, confirming anthropogenic contributions of Cu, Zn, Pb and Cd to the sediments. The onset of metal contamination above background levels occurred at a depth between 43 and 49 cm, with maximum concentrations noted near 20 cm for Cu, Zn, Cd and Pb. Lead isotope ratios were determined in sediments using sector field ICP-MS, and were found to be 36.5-38.8, 16.5-18.7 and 1.07-1.20 for (208)Pb/(204)Pb, (206)Pb/(204)Pb and (206)Pb/(207)Pb ratios, respectively. Major Australian ores processed at the refinery over the previous ~90 years include those from Broken Hill, Rosebery, Mt Isa, Elura, Hellyer and Century deposits. Anthropogenic impact by Pb with Broken Hill type isotopic ratio was initially evident in the core at 43-49 cm. The introduction of Rosebery and Elura ores to the refinery was also clearly noted. Pb isotope ratios further highlight that the Derwent River has been exposed to a greater impact by anthropogenic Pb in comparison to other major Tasmanian rivers, namely the Huon and Tamar.

  3. Pb Concentration and Stable PB Isotopes in Dated-Core Sediments in the Ulleung Basin, East/japan Sea

    NASA Astrophysics Data System (ADS)

    Woo, J.; Choi, M.; Kim, D.

    2008-12-01

    This study investigated temporal and spatial variation of Pb and stable Pb isotopes accumulated in Ulleung Basin core sediments (12) using MC ICP/MS in order to identify the sources of anthropogenic Pb in the East/Japan Sea. Leached (1M HCl) Pb concentration and isotope ratios (207Pb/206Pb and 208Pb/206Pb) ware constant at around 20 mg/kg and 0.845 and 2.092 from 1700 to 1930 year, respectively and increased steadily up to 40 mg/kg and 0.873 to 2.129 at the beginning of 2000s, increased up to twice in concentration and as much as 3.31% and 1.64%. On the other hand, residual Pb concentrations were nearly constant for past 400 yrs. From the vertical profiles of Pb concentration and two end-members mixing model, anthropogenic Pb concentration and isotope ratios were estimated. The transport pathways of anthropogenic Pb could be estimated from 1) the comparison between the inventories of excess 210Pb in each sediment column and the input fluxes from the atmosphere and seawater column, 2) between the accumulation rate of anthropogenic Pb and mass accumulation rate of sediments. From the detailed evaluation for the pathways and isotope ratios of anthropogenic Pb, we proposed probable source of anthropogenic Pb. Pb emission by coal burning from the China and Korea initiated the accumulation of anthropogenic Pb in the sediments of East/Japan Sea from 1930s. The accumulation of Pb increased by the addition of anti-nocking agents from both countries untill beginning of 1990s, but from the middle of 1990s to the present, the phase-out of gasoline additives and the rapid increase of coal burning from China maintained the atmospheric Pb levels in the Ulleung basin nearly similar to before. However the local sources (e.g. ocean dumping) within this basin might take an important role in the rapid increase of anthropogenic Pb accumulation in slope areas from the middle of 1990s.

  4. Nd, Sr, Pb, Ar, and O isotopic systematics of Sturgeon Lake kimberlite, Saskatchewan, Canada: constraints on emplacement age, alteration, and source composition

    NASA Astrophysics Data System (ADS)

    Hegner, E.; Roddick, J. C.; Fortier, S. M.; Hulbert, L.

    1995-06-01

    Rb-Sr isotopic dating of phlogopite megacryst samples separated from Sturgeon Lake kimberlite, Saskatchewan, yields a crystallization age of 98±1 Ma (2 σ, MSWD=1.2; 87Sr/86Sr( t)=0.7059). The 40Ar/39Ar analyses of a phlogopite megacryst sample indicate the presence of large amounts of excess 40Ar and yield an excessively old age of ˜410 Ma. Assessment of the Ar data using isotope correlation plots indicates clustering of the data points about a mixing line between the radiogenic 40Ar component at 98 Ma and a trapped component with uniform 36Ar/40Ar and Cl/40Ar. Values of δ 18O as high as +20‰ (VSMOW) for calcite from the groundmass and a whole-rock sample indicate pervasive low-temperature alteration. The δ 13C of matrix carbonate is -11.3‰ (PDB), slightly lighter than typical values from the literature. The δ 18O values of about +5‰ (VSMOW) for brown phlogopite megacrysts may be primary, green phlogopites are interpreted to be an alteration product of the brown variety and are 2‰ heavier. Initial Nd-Sr-Pb isotopic ratios for a whole-rock sample ( ɛ Nd=+0.8; 87Sr/86Sr=0.7063, 206Pb/204Pb=18.67, 207Pb/204Pb=15.54, 208Pb/204Pb=38.97) suggest an affinity with group I kimberlites. Initial ɛ Nd values of +1.7 and +0.5 (87Sr/86Sr( t)=0.7053 and 0.7050) for eclogitic and lherzolitic garnet megacryst samples, and values of 0.0 for two phlogopite megacryst samples reflect an origin from an isotopically evolving melt due to assimilation of heterogeneous mantle. Lilac high-Cr lherzolitic garnet megacrysts give an unusually high ɛ Nd(98. Ma) of +28.6 (87Sr/86Sr=0.7046) indicating a xenocrystic origin probably from the lithospheric mantle. The very radiogenic 87Sr/86Sr and 206Pb/204Pb ratios of the kimberlite are consistent with melting of EM II (enriched) mantle components.

  5. Origin and fate of sulfide liquids in hotspot volcanism (La Réunion): Pb isotope constraints from residual Fe-Cu oxides

    NASA Astrophysics Data System (ADS)

    Vlastélic, I.; Gannoun, A.; Di Muro, A.; Gurioli, L.; Bachèlery, P.; Henot, J. M.

    2016-12-01

    Immiscible sulfide liquids in basaltic magmas play an important role in trace metal transport and the sulfur budget of volcanic eruptions. However, sulfides are transient phases, whose origin and fate are poorly constrained. We address these issues by analyzing sulfide destabilization products preserved in lavas from La Réunion Island. Iron oxide globules and coatings, typically 20-80 μm in size, were found to occur in vesicles of differentiated lavas from Piton des Neiges, and recent pumice samples from Piton de la Fournaise. Field and mineralogical evidence indicates that the iron oxides are syn-eruptive phases not resulting from hydrothermal processes. Samples were first studied by Scanning Electron Microscopy. The globules were separated, whereas the smaller spherules and coatings were concentrated by magnetic sorting and acid leaching, and samples were processed through wet chemistry. The Fe oxide phases comprise 49-74 wt.% Fe, 26-40 wt.% O, and up to 6 wt.% Cu, 811 ppm Ni, 140 ppm Bi, and 8.5 ppm Pb. Compared to the host lava, Cu, Ni, and Bi are enriched by a factor of 101-103. Systematic Pb isotope disequilibrium (between 500 ppm and 2.9% for 206Pb/204Pb) exists between Fe oxides and host rocks, with Fe oxides generally displaying less radiogenic ratios. Unradiogenic Pb is a typical signature of sulfide, which tends to concentrate Pb, but not its parent elements U and Th. Thus, both the chemical and isotopic compositions of the vesicle-hosted Fe oxides suggest that they are more or less direct products of the destabilization of immiscible sulfide liquids. Although Pb dominantly partitions into the gas phase during sulfide breakdown, the original Pb isotope signature of sulfide is preserved in the residual oxide. The composition estimated for the parent sulfides (206Pb/204Pb = 18.20-18.77, 207Pb/204Pb = 15.575, and 208Pb/204Pb = 38.2-38.8) precludes a genetic link with the La Réunion plume, and suggests a lithospheric or crustal origin. It is estimated

  6. Upper and lower crust recycling in the source of CAMP basaltic dykes from southeastern North America

    NASA Astrophysics Data System (ADS)

    Callegaro, Sara; Marzoli, Andrea; Bertrand, Hervé; Chiaradia, Massimo; Reisberg, Laurie; Meyzen, Christine; Bellieni, Giuliano; Weems, Robert E.; Merle, Renaud

    2013-08-01

    The densest dykes swarm of the Central Atlantic magmatic province (CAMP) occur in southeastern North America (SENA) and were intruded between 202 and 195 Ma during Pangea break-up. New combined geochemical data (major and trace elements, Sr-Nd-Pb-Os isotopes) constrain the mantle source of these magmatic bodies and their evolution path. While Sr-Nd isotopic compositions for SENA rocks (87Sr/86Sr200Ma 0.70438-0.70880 and 143Nd/144Nd200Ma 0.51251-0.51204) fall within the low-Ti CAMP field, Pb-Pb isotopes (206Pb/204Pb200Ma 17.46-18.85, 207Pb/204Pb200Ma 15.54-15.65, 208Pb/204Pb200Ma 37.47-38.76) are peculiar to this area of the CAMP and cover a considerable span of compositions, especially in 206Pb/204Pb200Ma. Given the generally unradiogenic Os isotopic compositions (187Os/188Os200Ma 0.127-0.144) observed and the lack of correlation between these and other geochemical markers, crustal contamination during the evolution of SENA dykes must have been limited (less than 10%). Thus the isotopic variation is interpreted to reside primarily within the mantle source. These observations, coupled with typical continental signatures in trace elements (positive anomaly in Pb and negative anomalies in Ti and Nb), require another means of conveying a continental flavor to these magmas, which is here hypothesized to be the shallow recycling within the upper mantle of subducted lower and upper crustal materials. Pseudo-ternary mixing models show that a maximum of 10% recycled crust is enough to explain their trace element patterns as well as their isotopic heterogeneity. Looking at the larger picture of the origin of the CAMP, the thermal contribution of a mantle plume cannot be ruled out due to the relatively high mantle potential temperatures (1430-1480 °C) calculated for high-Fo SENA olivines. Nevertheless, our results suggest that the chemical involvement of a mantle plume is negligible (less than 5%) if either a C- or an EM-flavored plume is considered. Rather, the possibility

  7. Melt inclusions in the olivine from the Nantianwan intrusion: Implications for the parental magma of Ni-Cu-(PGE) sulfide-bearing mafic-ultramafic intrusions of the ∼260 Ma Emeishan large igneous province (SW China)

    NASA Astrophysics Data System (ADS)

    Zhang, Le; Ren, Zhong-Yuan; Wang, Christina Yan

    2017-02-01

    Olivine-hosted melt inclusions provide an archive of the parental magma and early magma history that is unavailable from bulk-rock analyses of cumulates. For those olivine-bearing mafic-ultramafic intrusions, a combined in situ analysis of major elements and Pb isotopic compositions for the melt inclusions and host olivine crystals may provide an effective way to understand the nature of the parental magma of the intrusions. In this study, we take the Nantianwan intrusion in the Emeishan large igneous province (SW China) as an example to analyze the melt inclusions and the host olivine. The Nantianwan intrusion is mainly composed of gabbronorite, with minor olivine gabbro. The olivine crystals in the olivine gabbro have Fo contents varying from 81.1 to 89.2 and Ni from 0.05 to 0.30 wt.%. The melt inclusion hosted in the most Mg-rich olivine has 50.9 wt.% SiO2, 1.0 wt.% TiO2, 15.1 wt.% MgO and 2.9 wt.% Na2O + K2O, indicating that the parental magma of the intrusion was of high-Mg basaltic composition. The melt inclusions overall have 208Pb/206Pb ratios of 2.0567-2.1032 and 207Pb/206Pb of 0.8287-0.8481, similar to the Pb isotopic compositions of the Emeishan flood basalts and consistent with insignificant crustal contamination. Given that the Nantianwan intrusion contains the most Mg-rich olivine among the Ni-Cu-(PGE) sulfide-bearing mafic-ultramafic intrusions in the Emeishan LIP, we infer that the composition of the melt inclusion in the most Mg-rich olivine from the Nantianwan intrusion may represent the least evolved parental magma of the Ni-Cu-(PGE) sulfide-bearing mafic-ultramafic intrusions in the Emeishan LIP. This can be further used to constrain the magma process related to Ni-Cu-(PGE) sulfide mineralization.

  8. Sources of granite magmatism in the Embu Terrane (Ribeira Belt, Brazil): Neoproterozoic crust recycling constrained by elemental and isotope (Sr-Nd-Pb) geochemistry

    NASA Astrophysics Data System (ADS)

    Alves, Adriana; Janasi, Valdecir de Assis; Campos Neto, Mario da Costa

    2016-07-01

    Whole rock elemental and Sr-Nd isotope geochemistry and in situ K-feldspar Pb isotope geochemistry were used to identify the sources involved in the genesis of Neoproterozoic granites from the Embu Terrane, Ribeira Belt, SE Brazil. Granite magmatism spanned over 200 Ma (810-580 Ma), and is dominated by crust-derived relatively low-T (850-750 °C, zircon saturation) biotite granites to biotite-muscovite granites. Two Cryogenian plutons show the least negative εNdt (-8 to -10) and highest mg# (30-40) of the whole set. Their compositions are strongly contrasted, implying distinct sources for the peraluminous (ASI ∼ 1.2) ∼660 Ma Serra do Quebra-Cangalha batholith (metasedimentary rocks from relatively young upper crust with high Rb/Sr and low Th/U) and the metaluminous (ASI = 0.96-1.00) ∼ 630 Ma Santa Catarina Granite. Although not typical, the geochemical signature of these granites may reflect a continental margin arc environment, and they could be products of a prolonged period of oceanic plate consumption started at ∼810 Ma. The predominant Ediacaran (595-580 Ma) plutons have a spread of compositions from biotite granites with SiO2 as low as ∼65% (e.g., Itapeti, Mauá, Sabaúna and Lagoinha granites) to fractionated muscovite granites (Mogi das Cruzes, Santa Branca and Guacuri granites; up to ∼75% SiO2). εNdT are characteristically negative (-12 to -18), with corresponding Nd TDM indicating sources with Paleoproterozoic mean crustal ages (2.0-2.5 Ga). The Guacuri and Santa Branca muscovite granites have the more negative εNdt, highest 87Sr/86Srt (0.714-0.717) and lowest 208Pb/206Pb and 207Pb/206Pb, consistent with an old metasedimentary source with low time-integrated Rb/Sr. However, a positive Nd-Sr isotope correlation is suggested by data from the other granites, and would be consistent with mixing between an older source predominant in the Mauá granite and a younger, high Rb/Sr source that is more abundant in the Lagoinha granite sample. The

  9. Dynamic variability of dissolved Pb and Pb isotope composition from the U.S. North Atlantic GEOTRACES transect

    NASA Astrophysics Data System (ADS)

    Noble, Abigail E.; Echegoyen-Sanz, Yolanda; Boyle, Edward A.; Ohnemus, Daniel C.; Lam, Phoebe J.; Kayser, Rick; Reuer, Matt; Wu, Jingfeng; Smethie, William

    2015-06-01

    This study presents dissolved Pb concentration and isotopic composition distributions from GEOTRACES GA03, the U.S. North Atlantic Transect. Pb in the ocean is primarily derived from anthropogenic sources and Pb fluxes into the North Atlantic Ocean have been steadily decreasing following the phase-out of alkyl leaded gasoline usage in North America and Europe between 1975 and 1995. A compilation of dissolved Pb profiles from three stations occupied repeatedly during the last three decades reveals a dramatic decrease in concentrations within the surface layers and the thermocline maxima, although elevated concentrations greater than 60 pmol/kg are still observed in the center of the North Atlantic gyre where ventilation timescales are longer than at the western boundary. The evolution of stable Pb isotopes at these stations shows a shift from dominantly North American-like composition in surface waters in the early 1980s towards a more European-like composition in later years. The most recent shallow signatures at the Bermuda Atlantic Time Series station (BATS) show an even more recent trend returning to higher 206Pb/207Pb ratios after the completed phase-out of leaded gasoline in Europe, presumably because recently deposited Pb is more strongly influenced by industrial and incineration Pb than by residual alkyl leaded gasoline utilization. In surface waters, trends toward a more prominent European influence are also found in the middle of the basin and toward the European coast, coincident with higher concentrations of surface dissolved Pb. Scavenging of anthropogenic Pb is observed within the TAG hydrothermal plume, and it is unclear if there is any significant contribution to deep water by basaltic Pb leached by hydrothermal fluids. In the upper water column, many stations along the transect show Pb concentration maxima at ~100 m depth, coincident with a low 206Pb/207Pb isotopic signature that is typical of European emission sources. Although Pb ores from the

  10. On the determination of the pion effective mass in nuclei from pionic atoms

    NASA Astrophysics Data System (ADS)

    Friedman, E.; Gal, A.

    1998-07-01

    The binding energies of the deeply bound 1s and 2p states in pionic atoms of 207Pb, recently established experimentally in the 208Pb(d,3He) reaction, have been used by several groups to derive the pion effective mass in nuclear matter. We show that these binding energies are fully consistent with `normal' pionic atoms and that the real part of the pion-nucleus potential at the center of 207Pb is 28+/-3 MeV and not 20 MeV as suggested previously.

  11. Isoscalar [ital M]1 strength in lead

    SciTech Connect

    Alarcon, R.; Choi, S. ); Laszewski, R.M.; Dale, D.S. )

    1993-09-01

    Highly polarized tagged photons were used to measure the distribution of [ital M]1 transition strength in [sup 206]Pb at excitations between 5.5 and 6.9 MeV. The total [ital M]1 strength found in this energy range is consistent with that reported in [sup 208]Pb. For the isoscalar state at 5.8 MeV in [sup 206]Pb, [ital B]([ital M]1[up arrow])=(0.72[plus minus]0.15)[mu][sub [ital N

  12. Major, trace element and isotope geochemistry (Sr-Nd-Pb) of interplinian magmas from Mt. Somma-Vesuvius (Southern Italy)

    USGS Publications Warehouse

    Somma, R.; Ayuso, R.A.; de Vivo, B.; Rolandi, G.

    2001-01-01

    compositions in the interplinian rocks show a tendency to become slightly more radiogenic with age, from the Protohistoric (143Nd/144Nd=0.51240-0.51247) to Ancient Historic (143Nd/144Nd=0.51245-0.51251). Medieval interplinian activity (143Nd/144Nd: 0.51250-0.51241) lacks meaningful internal trends. All the interplinian rocks have virtually homogeneous compositions of 207Pb/204Pb and 208Pb/204Pb in acid-leached residues (207Pb/204Pb ???15.633 to 15.687, 208Pb/204Pb ???38.947 to 39.181). Values of 206Pb/204Pb are very distinctive, however, and discriminate among the three interplinian cycles of activity (Protohistoric: 18.929-18.971, Ancient Historic: 19.018-19.088, Medieval: 18.964-19.053). Compositional trends of major, trace element and isotopic compositions clearly demonstrate strong temporal variations of the magma types feeding the Somma-Vesuvius activity. These different trends are unlikely to be related only to low pressure evolutionary processes, and reveal variations of parental melt composition. Geochemical data suggest a three component mixing scheme for the interplinian activity. These involve HIMU-type and DMM-type mantle and Calabrian-type lower crust. Interaction between these components has taken place in the source; however, additional quantitative constraints must be acquired in order to better discriminate between magma characteristics inherited from the sources and those acquired during shallow level evolution.

  13. The origin of the Maozu carbonate-hosted Pb-Zn deposit, southwest China: Constrained by C-O-S-Pb isotopic compositions and Sm-Nd isotopic age

    NASA Astrophysics Data System (ADS)

    Zhou, Jiaxi; Huang, Zhilong; Yan, Zaifei

    2013-09-01

    The Maozu Pb-Zn deposit, located on the western margin of the Yangtze Block, southwest China, is a typical carbonate-hosted deposit in the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province with Pb + Zn reserves of about 2.0 million tonnes grading 4.15 wt.% Pb and 7.25 wt.% Zn. Its ore bodies are hosted in Sinian (635-541 Ma) Dengying Formation dolostone and show stratiform, vein and irregular textures. Ores are composed of sphalerite, galena, pyrite, calcite, dolomite, quartz and fluorite with massive, banded, disseminated and veined structures. The C-O-Sm-Nd isotopic compositions of hydrothermal calcites and S-Pb isotopic compositions of sulfides were analyzed to constrain the origin of the Maozu deposit. δ13CPDB and δ18OSMOW values of hydrothermal calcites range from -3.7‰ to -2.0‰ and +13.8‰ to +17.5‰, respectively, and plot near the marine carbonate rocks field in a plot of δ13CPDB vs. δ18OSMOW, with a negative correlation. It suggests that CO2 in the hydrothermal fluids was mainly originated from marine carbonate rocks, with limited influence from sedimentary organic matter. δ34SCDT values of sulfides range from +9.9‰ to +19.2‰, similar to that of Cambrian to Triassic seawater sulfate (+15‰ to +35‰) and evaporate (+15‰ to +30‰) in the Cambrian to Triassic sedimentary strata. It suggests that reduced sulfur was derived from evaporate in sedimentary strata by thermo chemical sulfate reduction. Sulfides have low radiogenic Pb isotope compositions (206Pb/204Pb = 18.129-18.375, 207Pb/204Pb = 15.640-15.686 and 208Pb/204Pb = 38.220-38.577) that plot in the field between upper crust and the orogenic belt evolution curve in the plot of 207Pb/204Pb vs. 206Pb/204Pb, and similar to that of age corrected Proterozoic basement rocks (Dongchuan and Kunyang Groups). This indicates that ore-forming metals were mainly derived from basement rocks. Hydrothermal calcite yields a Sm-Nd isotopic age of 196 ± 13 Ma, possibly reflecting the timing of Pb

  14. Petrogenesis of pillow basalts from Baolai in southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Liu, Chih-Chun; Yang, Huai-Jen

    2016-04-01

    The pillow basalts from Baolai in southwestern Taiwan have been inferred to bear Dupal signautres based on their Th/Ce ratio, linking the Baolai basalts to the South China Sea (SCS) seamounts that are characterized by Dupal Pb isotope signatures (Smith and Lewis, 2007). In this study, thirty-two Baolai basalt samples were analyzed for abundances of major and trace elements as well as Pb and Nd isotope ratios to verify their Dupal characters and to constrain their petrogenesis significance. The Baolai basalts contain 4-10 % L.O.I.. Three stages of alteration are inferred from plots of L.O.I. abundance versus concentrations major oxides as well as mineral textures and compositions. The first alteration stage was characterized by albitization that converted Ca-rich plagioclase to albite. The second alteration stage was dominated by chloritization of olivine and augite, resulting in increases in L.O.I. abundance. The last alteration stage is represented by formation of secondary calcite in vesicles and cracks. These alteration processes reflect interaction with seawater and apparently did not affect the magmatic Pb isotope composition for the low Pb concentration in seawater. Relative to the North Hemisphere Reference Line (NHRL), the Baolai pillow basalts have higher 208Pb/204Pb ratios at a given 206Pb/204Pb value, showing Dupal anomaly. For their relatively higher 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios, the Baolai basalts are distinct from majority of the Cenozoic basalts in the Hainan-Leizhou peninsula, the Indochina peninsula, and the SCS seamounts, for which derivation from the Hainan mantle plume has been recently proposed (Wang et al., 2013). In contrast, the Baolai basalts and the Cenozoic basalts from eastern Guangdong at southeastern China have similar Pb and Nd isotope compositions, indicating derivation from similar mantle sources. However, the Baolai basalts have lower abundance ratios of Zr/Hf (40.3-45.6 versus 46.5-50.5), La/Yb (12

  15. Reconstructing the environmental impact of smelters using Pb isotope analyses of peat cores from bogs: Flin Flon, Manitoba and Harjavalta, Finland

    NASA Astrophysics Data System (ADS)

    Shotyk, W.

    2012-04-01

    Located on the Manitoba - Saskatchewan border, the city of Flin Flon has been home to a metallurgical complex since 1930, processing Cu and Zn ores from surrounding mines and consisting of a concentrator, Zn plant, and Cu smelter. Peat cores were collected from two sites, dated using 210Pb, and measured for a broad suite of potentially toxic trace metals. A peat core collected from the bog at Kotyk Lake (30 km NE of FF) shows declines in 206Pb/207Pb from the natural "background" values of 1.25 at the base of the core, to a minimum of 1.02. A peat core collected from the bog at Sask Lake (88 km NW of FF) shows declines in 206Pb/207Pb from the natural "background" values of 1.35 at the base of the core to a minimum of 1.05. But the isotopic evolution of Pb shows significantly declines in 206Pb/207Pb beginning in the late 1800's, presumably because of long-range atmospheric transport from other sources. The 206Pb/207Pb values increase in both cores starting in the 1960's, and reach a recent maximum in the 1990's, apparently reflecting the growing use and eventually phase out of leaded gasoline use. Since the 1990's, the 206Pb/207Pb have continued their decline, apparently reflecting the elimination of leaded gasoline and the growing relative importance of Pb from the smelter. The temporal evolution in Pb enrichment factors follows the history of the metallurgical complex, with the maximum EF values (calculated using Sc) reaching maxima of ca. 100 x (Kotyk Lake) and 10 x (Sask Lake). The maximum rates of atmospheric Pb accumulation are approximately 1200 and 120 μg/m2/yr, respectively. In Finland, peat cores were taken from three bogs: the Pyhäsuo mire in SW Finland, 6 km NE from the Cu Ni smelter at Harjavalta (HAR); at the Viurusuo complex in eastern Finland, 8 km SW of the Cu Ni mine in the town of Outokumpu (OUT); and at Hietajärvi (HJ), in the Patvinsuo National Park of eastern Finland. The cores from HJ and OUT document 3,000 years of anthropogenic Pb and

  16. Giant M1 resonance in Pb

    SciTech Connect

    Laszewski, R.M.; Rullhusen, P.; Hoblit, S.D.; LeBrun, S.F.

    1985-02-11

    Highly polarized tagged photons were used to measure the distribution of M1 transition strength in /sup 206/Pb at excitations between 6.7 and 8.1 MeV. The observed B(up-arrowM1) of about 19..mu../sub 0//sup 2/ can account for most of the isovector M1 strength that is expected in the Pb nucleus. This result in /sup 206/Pb is compared with the current experimental situation in /sup 208/Pb. The discrepancy between predicted and observed M1 strengths in /sup 208/Pb can probably be attributed to local fragmentation of the strength into states that are too weak to have yet all been identified.

  17. Lead isotope exchange between dissolved and fluvial particulate matter: a laboratory study from the Johor River estuary

    NASA Astrophysics Data System (ADS)

    Chen, Mengli; Boyle, Edward A.; Lee, Jong-Mi; Nurhati, Intan; Zurbrick, Cheryl; Switzer, Adam D.; Carrasco, Gonzalo

    2016-11-01

    Atmospheric aerosols are the dominant source of Pb to the modern marine environment, and as a result, in most regions of the ocean the Pb isotopic composition of dissolved Pb in the surface ocean (and in corals) matches that of the regional aerosols. In the Singapore Strait, however, there is a large offset between seawater dissolved and coral Pb isotopes and that of the regional aerosols. We propose that this difference results from isotope exchange between dissolved Pb supplied by anthropogenic aerosol deposition and adsorbed natural crustal Pb on weathered particles delivered to the ocean by coastal rivers. To investigate this issue, Pb isotope exchange was assessed through a closed-system exchange experiment using estuarine waters collected at the Johor River mouth (which discharges to the Singapore Strait). During the experiment, a known amount of dissolved Pb with the isotopic composition of NBS-981 (206Pb/207Pb = 1.093) was spiked into the unfiltered Johor water (dissolved and particulate 206Pb/207Pb = 1.199) and the changing isotopic composition of the dissolved Pb was monitored. The mixing ratio of the estuarine and spike Pb should have produced a dissolved 206Pb/207Pb isotopic composition of 1.161, but within a week, the 206Pb/207Pb in the water increased to 1.190 and continued to increase to 1.197 during the next two months without significant changes of the dissolved Pb concentration. The kinetics of isotope exchange was assessed using a simple Kd model, which assumes multiple sub-reservoirs within the particulate matter with different exchange rate constants. The Kd model reproduced 56% of the observed Pb isotope variance. Both the closed-system experiment and field measurements imply that isotope exchange can be an important mechanism for controlling Pb and Pb isotopes in coastal waters. A similar process may occur for other trace elements. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

  18. Pb-concentrations and Pb-isotope ratios in soils collected along an east-west transect across the United States

    USGS Publications Warehouse

    Reimann, Clemens; Smith, David B.; Woodruff, Laurel G.; Flem, Belinda

    2011-01-01

    Analytical results for Pb-concentrations and isotopic ratios from ca. 150 samples of soil A horizon and ca. 145 samples of soil C horizon collected along a 4000-km east–west transect across the USA are presented. Lead concentrations along the transect show: (1) generally higher values in the soil A-horizon than the C-horizon (median 21 vs. 16.5 mg/kg), (2) an increase in the median value of the soil A-horizon for central to eastern USA (Missouri to Maryland) when compared to the western USA (California to Kansas) (median 26 vs. 20 mg/kg) and (3) a higher A/C ratio for the central to eastern USA (1.35 vs. 1.14). Lead isotopes show a distinct trend across the USA, with the highest 206Pb/207Pb ratios occurring in the centre (Missouri, median A-horizon: 1.245; C-horizon: 1.251) and the lowest at both coasts (e.g., California, median A-horizon: 1.195; C-horizon: 1.216). The soil C-horizon samples show generally higher 206Pb/207Pb ratios than the A-horizon (median C-horizon: 1.224; A-horizon: 1.219). The 206Pb/207Pb-isotope ratios in the soil A horizon show a correlation with the total feldspar content for the same 2500-km portion of the transect from east-central Colorado to the Atlantic coast that shows steadily increasing precipitation. No such correlation exists in the soil C horizon. The data demonstrate the importance of climate and weathering on both Pb-concentration and 206Pb/207Pb-isotope ratios in soil samples and natural shifts thereof in the soil profile during soil-forming processes.

  19. The lead (Pb) isotope signature, behaviour and fate of traffic-related lead pollution in roadside soils in The Netherlands.

    PubMed

    Walraven, N; van Os, B J H; Klaver, G Th; Middelburg, J J; Davies, G R

    2014-02-15

    In this study the origin, behaviour and fate of anthropogenic Pb in sandy roadside soils were assessed by measuring soil characteristics, Pb isotope composition and content. In 1991 and 2003 samples were taken at different depth intervals at approximately 8 and 75 m from two highways in The Netherlands. The Pb isotope composition of the litter layer ((206)Pb/(207)Pb=1.12-1.14) differs from the deeper soil samples ((206)Pb/(207)Pb=1.20-1.21). Based on a mixing model it is concluded that the samples contain two Pb sources: natural Pb and anthropogenic Pb, the latter mainly derived from gasoline. (206)Pb/(207)Pb ratios demonstrate that the roadside soils were polluted to a depth of ~15 cm. Within this depth interval, anthropogenic Pb content is associated with organic matter. Although Pb pollution only reached a depth of ~15 cm, this does not mean that the topsoils retain all anthropogenic Pb. Due to the low pH and negligible binding capacity of soils at depths >15 cm, anthropogenic Pb migrated towards groundwater after reaching depths of >15 cm. The Pb isotope composition of the groundwater ((206)Pb/(207)Pb=1.135-1.185) establishes that groundwater is polluted with anthropogenic Pb. The contribution of anthropogenic Pb to the groundwater varies between ~30 and 100%. Based on the difference in soil Pb content and Pb isotope compositions over a period of 12 years, downward Pb migration is calculated to vary from 72 ± 95 to 324 ± 279 mg m(-2)y(-1). Assuming that the downward Pb flux is constant over time, it is calculated that 35-90% of the atmospherically delivered Pb has migrated to the groundwater.

  20. U-Th-Pb zircon ages of some Keweenawan Supergroup rocks from the south shore of Lake Superior

    USGS Publications Warehouse

    Zartman, R.E.; Nicholson, S.W.; Cannon, W.F.; Morey, G.B.

    1997-01-01

    New single-crystal zircon U-Th-Pb ages for plutonic and rhyolitic Keweenawan Supergroup rocks from the south shore of Lake Superior provide geochronological constraints on magmatic evolution associated with the 1.1 Ga Midcontinent rift. Analyses of a granophyric phase of the Mineral Lake intrusion and the Meilen granite, both parts of the Meilen Intrusive Complex, and a laterally extensive rhyolite from the top of the Kallander Creek Volcanics have weighted average 207Pb/206Pb ages of 1102.0 ?? 2.8 Ma (N = 2), 1100.9 ?? 1.4 Ma (N = 5), and 1098.8 ?? 1.9 Ma (N = 4), respectively. Analyses of a pyroclastic rhyolite flow at the top of the Porcupine Volcanics result in variable 207Pb/206Pb ages that range from 1080 to 1137 Ma. This rhyolite exhibits a continuum between morphologically complex and simpler prismatic zircon crystals, the latter yielding concordant analyses having a weighted average 207Pb/206Pb age of 1093.6 ?? 1.8 Ma (N = 2). Four prismatic zircons from an aphyric rhyolite of the Chengwatana Volcanics in the Ashland syncline form a linear array intersecting concordia at 1094.6 ?? 2.1 Ma (MSWD = 1.3). Another presumed Chengwatana rhyolite recovered from drill core intersecting the Hudson-Afton horst in southeast Minnesota yielded only ???20 morphologically indistinguishable zircons. Six analyses give 207Pb/206Pb ages ranging from 1112 to 1136 Ma, including one analysis with a virtually concordant age of 1130 Ma. This age, however, is considerably older than that obtained for the Chengwatana Volcanics in the Ashland syncline or any other precisely dated rock from the Midcontinent rift.

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

    PubMed

    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).

  2. SIMS and TIMS U-Th-Pb Geochronology of Zircon From the Bishop Tuff

    NASA Astrophysics Data System (ADS)

    Ickert, R. B.; Magee, C. W.; Mundil, R.

    2013-12-01

    ages of only 80 Ka with a mean age of less than 800 Ka. The precision of single-spot analyses are on the order of 4% (2σ), yielding an absolute precision of approximately × 30 ka per spot. Inferred common 206Pb concentrations are on the order of 2 ppb, yielding fractions of radiogenic 206Pb mostly higher than 98%. Common Pb corrections based on the so-called 207Pb and 208Pb methods yield nearly identical results. The agreement between both common Pb corrections eliminates the possibility of interfering species on the common Pb peak as a source of inaccuracy. These data show no evidence of an old (>850 Ka) component in this sample. There is no excess scatter, allowing the possibility that zircon crystallization took place over a very short period of time (<10 Ka), consistent with TIMS analyses. Single grain TIMS analyses from the same sample also show no evidence for protracted zircon crystallization. Preliminary leaching experiments of multi-grain samples (progressive dissolution) show no variation of Pb/U during individual leaching steps, suggesting that the within-grain age variation may be less than 10 Ka. A more comprehensive study including geochemical and geochronological analyses on volcanic products of the entire Long Valley Suite is crucial to better understand the timing of magma generation, crystal growth and eruptions of this volcanic system.

  3. Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

    USGS Publications Warehouse

    Bouse, R.M.; Ruiz, J.; Titley, S.R.; Tosdal, R.M.; Wooden, J.L.

    1999-01-01

    Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206Pb/204Pb = 17.34 to 22.66, 207Pb/204Pb = 15.43 to 15.96, and 208Pb/204Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206Pb/204Pb and higher model Th/U, and the southern subprovince has higher 206Pb/204Pb and

  4. Radiogenic Isotope Constraints on Plume - Lithosphere Interaction Beneath the Snake River Plain

    NASA Astrophysics Data System (ADS)

    Hanan, B. B.; Shervais, J. W.; Vetter, S. K.

    2006-12-01

    continental component. We tested this prediction with fifty basalts from along the SRP analyzed for major and trace contents and Pb, Sr, and Nd isotopes. The SRP Pb isotope results are consistent with mixing between an OIB-like plume component with 1% to 4% melt derived from about 2.8 Ga Wyoming-like enriched SCML and show that the relative amount of plume-like OIB component increases from 90-98% in the YP, to 98-99% in the central and western SRP. Basalts of the main phase CRBG (5), the central and eastern SRP, and the YP (6) show an overall decrease in 206Pb/204Pb and ^{143}Nd/^{144}Nd, variable 87Sr/86Sr, and increase in 207Pb/206Pb and ^{208}Pb/206Pb from west to east with distance from the Yellowstone caldera, with OIB-like values in Oregon and Washington toward values typical of the lower crust and lithosphere of the Wyoming Province along the SRP and YP. These results are consistent with a progressive decrease in craton thickness from east to west approaching the craton margin, a concomitant decrease in the age, and compositional heterogeneity in the lower crust and SCML beneath the SRP. (1) Camp and Ross, JGR 109, 2004; (2) Wooden and Mueller, EPSL 87, 1988; (3) Leeman et al., EPSL 75, 1985; (4) Wolf et al., GSA Abstracts with Programs 37, 2005; (5) Hooper, G3 1, 2000; (6) Doe, JGR 87, 1982.

  5. Zirconolite: A new U-Pb chronometer for mafic igneous rocks

    NASA Astrophysics Data System (ADS)

    Rasmussen, Birger; Fletcher, Ian R.

    2004-09-01

    Precise dates for mafic igneous events are essential for tectonic reconstructions and understanding mantle dynamics, mass extinctions, and paleoclimate. Zirconolite (CaZrTi2O7) is a uranium-bearing accessory mineral, found in a wide range of terrestrial and lunar rocks, that has been largely overlooked as a chronometer. In situ U-Pb geochronology of zirconolite from three dolerite intrusions in Western Australia demonstrates that it yields emplacement ages that are more precise than those obtained from coexisting zircon and baddeleyite. Dikes in the Stirling Range Formation give a zirconolite 207Pb/ 206Pb age of 1218 ± 3 Ma, indistinguishable from the less precise dates obtained from zircon (1215 ± 10 Ma) and baddeleyite (1217 ± 39 Ma) and coincident with dike emplacement in the adjacent craton margin and peak metamorphism in the Albany-Fraser orogen. Zirconolite from the 755 Ma Mundine Well dike swarm yields a 207Pb/206Pb age of 754 ± 5 Ma. Sills intruding the Proterozoic Manganese Group contain zirconolite crystals that give a 207Pb/206Pb age of 523 ± 14 Ma. Despite high U contents (550 ppm to 14,000 ppm) and greenschist facies metamorphism, zirconolite in these samples is apparently unaffected by loss of radiogenic Pb. Because of its remarkable properties for U-Pb geochronology, it may soon become the dominant tool for dating mafic igneous rocks as young as 500 Ma by ion microprobe, and thus will prove especially valuable in reconstructing Precambrian geologic history.

  6. Transboundary atmospheric lead pollution.

    PubMed

    Erel, Yigal; Axelrod, Tamar; Veron, Alain; Mahrer, Yitzak; Katsafados, Petros; Dayan, Uri

    2002-08-01

    A high-temporal resolution collection technique was applied to refine aerosol sampling in Jerusalem, Israel. Using stable lead isotopes, lead concentrations, synoptic data, and atmospheric modeling, we demonstrate that lead detected in the atmosphere of Jerusalem is not only anthropogenic lead of local origin but also lead emitted in other countries. Fifty-seven percent of the collected samples contained a nontrivial fraction of foreign atmospheric lead and had 206Pb/207Pb values which deviated from the local petrol-lead value (206Pb/207Pb = 1.113) by more than two standard deviations (0.016). Foreign 206Pb/207Pb values were recorded in Jerusalem on several occasions. The synoptic conditions on these dates and reported values of the isotopic composition of lead emitted in various countries around Israel suggest that the foreign lead was transported to Jerusalem from Egypt, Turkey, and East Europe. The average concentration of foreign atmospheric lead in Jerusalem was 23 +/- 17 ng/m3, similar to the average concentration of local atmospheric lead, 21 +/- 18 ng/ m3. Hence, the load of foreign atmospheric lead is similar to the load of local atmospheric lead in Jerusalem.

  7. A lead isotopic assessment of tree bark as a biomonitor of contemporary atmospheric lead.

    PubMed

    Patrick, Gavin J; Farmer, John G

    2007-12-15

    The outermost bark layer of trees, predominantly Scots pine (Pinus sylvestris), was sampled at 82 non-urban locations from six arbitrarily designated areas (Northwest, Northeast, Central Highlands, Central and East, Central and Southwest, Southeast), throughout Scotland during 2002-2003 and analysed for lead concentration and stable lead isotopes by flame atomic absorption spectrometry (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. The mean lead concentration and mean (206)Pb/(207)Pb ratio (+/-1 standard deviation, SD) for bark samples from the areas were as follows: Northwest (8.0 mg kg(-1), 1.121+/-0.014, n=17), Northeast (8.9 mg kg(-1), 1.117+/-0.012, n=12), Central Highlands (11.3 mg kg(-1), 1.130+/-0.010, n=11), Central and East (35.3 mg kg(-1), 1.120+/-0.007, n=10), Central and Southwest (20.6 mg kg(-1), 1.125+/-0.018, n=22) and Southeast (34.4 mg kg(-1), 1.120+/-0.005, n=10), with an overall mean lead concentration of 18.5 mg kg(-1) (range 0.6-146 mg kg(-1), median 8.4 mg kg(-1)) and an overall mean (206)Pb/(207)Pb ratio of 1.122+/-0.014 (range 1.089-1.168, median 1.122). The overall mean (206)Pb/(207)Pb ratio for bark was therefore significantly lower (p<0.01, t test) than the mean atmospheric (206)Pb/(207)Pb ratio of 1.154+/-0.006 (range 1.144-1.167, n=50) and 1.154+/-0.010 (range 1.134-1.171, n=26) as determined in rainwater collected routinely at Glensaugh, Central Highlands, during 2002 and 2003, respectively. The bark (206)Pb/(207)Pb values, 90% of which lay between 1.10 and 1.14, were more akin to those recorded for the atmosphere (via rainwater, atmospheric particulates, moss, etc.) at various locations throughout Scotland during the 1990s, a decade over which the use of leaded petrol (mean (206)Pb/(207)Pb ratio=1.076+/-0.011) declined markedly before its complete withdrawal in 2000. This strongly suggests that the lead content and isotopic composition of tree bark from Scots pine, which reputedly sheds its outer

  8. Cross-Section Measurements for (n,xn) Reactions by In-Beam Gamma-Ray Spectroscopy

    SciTech Connect

    Pavlik, A.; Baumann, P.; Kerveno, M.; Rudolf, G.; Borcea, C.; Mihailescu, L.C.; Jericha, E.; Raskinyte, I.; Jokic, S.; Lukic, S.; Meulders, J.P.; Nolte, R.; Plompen, A.J.M.

    2005-05-24

    The nuclear reactions 207Pb(n,2n)206Pb and 232Th(n,5n)228Th were studied by measuring prompt gamma-ray emission spectra from the interaction of neutrons with an enriched 207Pb sample and a natTh sample. For 207Pb the measurements were performed at the white neutron beam of the GELINA neutron source at IRMM Geel in the neutron energy range up to 20 MeV. The Th measurements were done at the quasi-monoenergetic 7Li(p,n)7Be neutron source at the Universite Catholique de Louvain for five peak neutron energies in the range 29 MeV to 42 MeV. The measurements were complemented by model calculations using the code system EMPIRE-II.

  9. U-Pb Dating, whole rock and Sr-Nd-Pb-O isotope geochemistry of collisional magmatism in the CACC: Çiçekdaǧ igneous complex (ÇIC)

    NASA Astrophysics Data System (ADS)

    Deniz, Kiymet; Kagan Kadioglu, Yusuf; Stuart, Finlay; Ellam, Rob; Boyce, Adrian; Condon, Daniel

    2015-04-01

    these intrusive rocks have experienced fractional crystallisation coupled with crustal assimilation. The calcalkaline and alkaline series show enrichment in LILE and LREE relative to HFSE and HREE. These rocks have moderate 208Pb/204Pb (38.87-39.16) and 207Pb/204Pb (15.62-15.71) and high 206Pb/204Pb (18.76-18.81). Both trace element and Pb isotope data indicate enriched mantle source (EM-II). Mafic alkaline rocks differed with their low 206Pb/204Pb (17.55-17.62). These rocks are derived from subduction modified lithospheric mantle. The geochemistry and Sr-Nd-O isotope data of ophiolitic rocks and late alkaline dykes are very similar. Both of them have flat REE pattern, high 87Sr/86Sr and 143Nd/144Nd, low δ18O values (1.9-4.0), moderate 208Pb/204Pb (38.81-38.97, 38.51-38.91) and 207Pb/204Pb (15.62-15.70, 15.54-15.69) and high 206Pb/204Pb (18.37-18.77, 18.39-18.73). All data indicate heterogeneous mantle source. Trace element ratio diagrams suggest depleted mantle source and subduction enrichment for late alkaline dykes. Dy versus Dy/Yb diagram and calculated partial melting curves suggest 20-25% degree of partial melting of amphibole-phlogopite bearing spinel lherzolitic mantle sources. Ba/Rb versus Rb/Sr diagram indicate the presence of amphibole in the mantle source of ophiolitic rocks and phlogopite for the late alkaline dykes. U-Pb dating of zircon yielded crystallization ages of 73.74±0.027-73.78±0.046 and 73.78±0.071 for calcalkaline series and alkaline series, respectively. Both series are coexistence and may have coevally been confined from same sources.

  10. Isotope geochemistry and fluid inclusion study of skarns from Vesuvius

    USGS Publications Warehouse

    Gilg, H.A.; Lima, A.; Somma, R.; Belkin, H.E.; de Vivo, B.; Ayuso, R.A.

    2001-01-01

    We present new mineral chemistry, fluid inclusion, stable carbon and oxygen, as well as Pb, Sr, and Nd isotope data of Ca-Mg-silicate-rich ejecta (skarns) and associated cognate and xenolithic nodules from the Mt. Somma-Vesuvius volcanic complex, Italy. The typically zoned skarn ejecta consist mainly of diopsidic and hedenbergitic, sometimes "fassaitic" clinopyroxene, Mg-rich and Ti-poor phlogopite, F-bearing vesuvianite, wollastonite, gehlenite, meionite, forsterite, clinohumite, anorthite and Mg-poor calcite with accessory apatite, spinell, magnetite, perovskite, baddeleyite, and various REE-, U-, Th-, Zr- and Ti-rich minerals. Four major types of fluid inclusions were observed in wollastonite, vesuvianite, gehlenite, clinopyroxene and calcite: a) primary silicate melt inclusions (THOM = 1000-1050??C), b) CO2 ?? H2S-rich fluid inclusions (THOM = 20-31.3??C into the vapor phase), c) multiphase aqueous brine inclusions (THOM = 720-820??C) with mainly sylvite and halite daughter minerals, and d) complex chloride-carbonate-sulfate-fluoride-silicate-bearing saline-melt inclusions (THOM = 870-890??C). The last inclusion type shows evidence for immiscibility between several fluids (silicate melt - aqueous chloride-rich liquid - carbonate/sulfate melt?) during heating and cooling below 870??C. There is no evidence for fluid circulation below 700??C and participation of externally derived meteoric fluids in skarn formation. Skarns have considerably variable 206Pb/204Pb (19.047-19.202), 207Pb/204Pb (15.655-15.670), and 208Pb/204Pb (38.915-39.069) and relatively low 143Nd/144Nd (0.51211-0.51244) ratios. The carbon and oxygen isotope compositions of skarn calcites (??13CV-PDB = -5.4 to -1.1???; ??18OV-SMOW = 11.7 to 16.4???) indicate formation from a 18O- and 13C-enriched fluid. The isotope composition of skarns and the presence of silicate melt inclusion-bearing wollastonite nodules suggests assimilation of carbonate wall rocks by the alkaline magma at moderate depths (< 5

  11. Geochemical and Sr-Nd-Pb Isotopic Insights of the Low-Ti basalts from Paraná-Etendeka Igneous Province, Southern Brazil: Constraints on Petrogenesis and the Role of Crustal Contamination

    NASA Astrophysics Data System (ADS)

    Raposo, I.; Barreto, C. J.; Lima, E. F. D.; Lafon, J. M.; Sommer, C. A.; Waichel, B. L.

    2015-12-01

    The south hinge of the Torres Syncline in southernmost Brazil hosts a volcanic succession of pahoehoe and rubbly Gramado-type lavas belonging to the ~132 Ma Paraná-Etendeka Igneous Province. We employ local-scale stratigraphy in three distinct profiles (Santa Cruz do Sul-Herveiras, Morro da Cruz and Lajeado geologic sections) as guidelines for geochemical and Sr-Nd-Pb isotope studies in order to discuss the petrogenesis of lava flows in a single magma type and to quantitatively evaluate the role of crustal contamination and the potential contaminants involved. In all profiles, the lava flows exhibit compositions ranging from basalt to andesite with tholeiitic affinity. The compositional and isotopic variations are not systematic according to stratigraphy, implying that the magma chamber could have undergone periodic replenishments or distinct magma pulses through time or multiple plumbling systems may have existed. The andesites (SiO2 55-58 wt.%) with ponded pahoehoe morphology represent evolved melts at early stages of volcanism with strong susceptibility to crustal contamination as they established pathways to the surface. The olivine basalts (SiO2 47-50 wt.%) and basaltic andesites (SiO2 51-56 wt.%) showing compound morphology and simple pahoehoe morphology, respectively, could be explained by longer time residence of liquids in the crust with higher degrees of crustal assimilation than the ponded pahoehoe lavas. The basaltic andesites (SiO2 52-56 wt. %) with rubbly morphology are related to late differentiation process in shallow magma chambers. Crustal assimilation process accounts for the high initial 87Sr/86Sr ratios at 0.707798-0.715751, very low ɛNd between -8.36 and -5.41, high 206Pb/204Pb ratios at 18.424-18.865, with intermediate 207Pb/204Pb and 208Pb/204Pb ratios at 15.649-15.710 and 38.618-39.369, respectively. The isotopic variations require assimilation of both Paleoproterozoic and Neoproterozoic contaminants at variable degrees.

  12. Geochemical heterogeneities within the Crozet hotspot

    NASA Astrophysics Data System (ADS)

    Breton, Thomas; Nauret, François; Pichat, Sylvain; Moine, Bertrand; Moreira, Manuel; Rose-Koga, Estelle F.; Auclair, Delphine; Bosq, Chantal; Wavrant, Laurène-Marie

    2013-08-01

    The Crozet Plateau is a 54 Ma-old volcanic plateau that supports five islands characterized by recent volcanic manifestations that are the surface expression of a deep-mantle plume. Due to their remote location and difficult access, the Crozet Islands are poorly sampled. Both the petrological descriptions and geochemical data are scarce. Thus, the sources of the Crozet plume are still under debate. Similarly, the interactions between the Southwest Indian Ridge (SWIR) and the Crozet plume remain questioned. Here, we present a new set of isotopes (Pb, Sr, Nd and He), major and trace elements data on basalts from three islands of the Crozet Archipelago: Penguins, East, and Possession Islands. Our main purpose is to characterize the sources of the Crozet plume and to test its influence at regional scale. Two groups of lavas can be distinguished based on the isotopic data: East and Possession lavas, and Penguins lavas. Principal component analyses on our high-precision Pb isotopes data and literature data show that two mantle sources can explain most of the geochemical variability measured in Crozet lavas. A third minor contribution is however needed to fully explain the data. The entire set of isotopic compositions (Pb, Sr, Nd and He) can be explained by a mixing between three mantle sources: (1) a FOZO (Focus Zone) component, with 206Pb/204Pb higher than 19.5 and high 207Pb/204Pb, 208Pb/204Pb 87Sr/86Sr, 143Nd/144Nd and R/Ra (R/Ra=(He3/He4)sample/(He3/He4)atmosphere) ratios, that is mainly sampled Penguins lavas, (2) a component called “East-Possession” that is mostly sampled by the East-Possession lava group and which presents Pb, Sr and Nd isotope signatures similar to those of the Reunion-Mauritius Islands, and (3) a third minor contribution of the local Depleted MORB Mantle (DMM). The new He isotopes data on the Crozet plume allow us to propose that Crozet plume material is present in the segment of the Southwest Indian Ridge located between the Indomed (ITF

  13. Petrogenesis of the Yaochong granite and Mo deposit, Western Dabie orogen, eastern-central China: Constraints from zircon U-Pb and molybdenite Re-Os ages, whole-rock geochemistry and Sr-Nd-Pb-Hf isotopes

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Xu, Zhaowen; Qiu, Wenhong; Li, Chao; Yu, Yang; Wang, Hao; Su, Yang

    2015-05-01

    The Dabie orogen is among the most famous continent-continent collisional orogenic belts in the world, and is characterized by intensive post-collisional extension, magmatism and Mo mineralization. However, the genetic links between the mineralization and the geodynamic evolution of the orogen remain unresolved. In this paper, the Yaochong Mo deposit and its associated granitic stocks were investigated to elucidate this issue. Our new zircon U-Pb ages yielded an Early Cretaceous age (133.3 ± 1.3 Ma) for the Yaochong granite, and our molybdenite Re-Os dating gave a similar age (135 ± 1 Ma) for the Mo deposit. The Yaochong stock is characterized by high silica and alkali but low Mg, Fe and Ca. It is enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs: Rb, K, Th and U), but strongly depleted in heavy REEs, and high field strength elements (HFSEs: Nb, Ta, Ti and Y). The Yaochong granite has initial 87Sr/86Sr ratios of 0.7087-0.7096, and Pb isotopic ratios of (206Pb/204Pb)i = 16.599-16.704, (207Pb/204Pb)i = 15.170-15.618 and (208Pb/204Pb)i = 36.376-38.248. The granite has εNd(t) of -18.0 to -16.3 and εHf(t) values of -26.5 to -20.0. All these data indicate that the Yaochong granite is a high-K calc-alkaline fractionated I-type granite, and may have originated from partial melting of the thickened Yangtze continental crust. The Mo ores also show low radiogenic Pb isotopes similar to the Yaochong stock. Medium Re content in molybdenite (21.8-74.8 ppm) also suggests that the ore-forming materials were derived from the thickened lower crust with possibly minor mixing with the mantle. Similar to the Eastern Dabie orogen, the thickened crust beneath the Western Dabie orogen may also have experienced tectonic collapse, which may have exerted fundamental geodynamic controls on the two-stage Mo mineralization in the region.

  14. Geochemistry, geochronology and isotope geology of Nakfa intrusive rocks, northern Eritrea: products of a tectonically thickened Neoproterozoic arc crust

    NASA Astrophysics Data System (ADS)

    Teklay, M.; Kröner, A.; Mezger, K.

    2001-08-01

    The north-south-trending Neoproterozoic volcano-sedimentary plutonic associations in northern Eritrea are part of the Nubian Shield. The Nakfa intrusive rocks range in composition from gabbro to syeno-diorite to granite and alkaline syenite and intrude supracrustal rocks of volcanic and sedimentary origin. All granitoid rocks are metaluminous or slightly peraluminous and have typical I-type chemical signatures. The calc-alkaline intrusive rocks and the alkaline syenites have geochemical characteristics (e.g. low Nb values) typical of arc intrusives and plot as volcanic arc granites on various discriminant diagrams. Single zircon evaporation Pb-Pb ages and conventional multigrain U-Pb ages on zircons and titanites yielded emplacement ages of ˜620-640 Ma. These are comparable to those of adjacent juvenile terranes in the Nubian Shield. No pre-Pan-African rocks have so far been found in northern Eritrea. Isotopic data show a limited range, with initial ɛ Nd values ranging from 3.5 to 5.6 and initial Sr ratios from 0.7018 to 0.7037. The high positive initial ɛ Nd values and low initial Sr ratios indicate that the granitoid rocks were derived from a mantle and/or juvenile crustal source with no, or only insignificant, contribution from an older continental component. This is further supported by the absence of inherited zircons and the lack of rocks of continental affinity. Leached K-feldspars from Nakfa intrusive rocks have Pb isotope ratios ( 206Pb/ 204Pb = 17.60-17.88, 207Pb/ 204Pb = 15.49-15.53 and 208Pb/ 204Pb = 37.12-37.37) similar to those for 'oceanic leads' from Saudi Arabia, which are interpreted as manifesting a mantle source. Hence, the Pb isotope ratios, in agreement with the Sr and Nd isotopic data, indicate an insignificant involvement of older crustal components in the generation of Pan-African crust in northern Eritrea. The ages and isotopic characteristics of the Nakfa intrusive rocks are comparable to those of adjacent juvenile terranes in the

  15. Origin of lamprophyres by the mixing of basic and alkaline melts in magma chamber in Beiya area, western Yunnan, China

    NASA Astrophysics Data System (ADS)

    Xu, Xing-Wang; Zhang, Bao-Lin; Qin, Ke-Zhang; Mao, Qian; Cai, Xin-Ping

    2007-12-01

    Lamprophyres consisting mainly of diopside, phlogopite and K-feldspar formed in the early Tertiary around 60 Ma in the Beiya area and are characterized by low SiO 2 ± 46-50 wt.%), Rb (31-45 ppm) and Sr (225-262 ppm), high Al 2O 3, (11.2-13.1 wt.%), CaO (8.0-8.7 wt.%), MgO (11.5-12.1 wt.%), K 2O(4.9-5.5 wt.%), TiO 2 (2.9-3.3 wt.%) and REE (174-177 ppm), and compatible elements (e.g. Sc, Cr and Ni) and HSF elements (e.g. Th, U, Zr, Nb, Ta, Ti and Y), and low 143Nd/ 144Nd 0.512372-0.512536, middle 87Sr/ 86Sr 0.707322-0.707395, middle 206Pb/ 204Pb 18.50-18.59, 207Pb/ 204Pb 15.60-15.65 and 208Pb/ 204Pb 38.75-38.8. These rocks developed peculiar quartz megacrysts with poly-layer reaction zones, melt inclusions, and partial melted K-feldspar and plagioclase inclusions, and plastic shapes. Important features of these rocks include: (1) hybrid composition of elements, (2) abrupt increase of SiO 2 content of the melt, recorded by zoned diopside, (3) development of sanidine and aegirine-augite reaction zones, (4) alkaline melt and partial melted K-feldspar and plagioclase inclusions, (5) deformed quartz inclusions associated with quartz megacrysts, (6) the presence of quartz megacrysts in plastic shape with their parent melts, (7) the occurrence of olivine, high-MgO ilmenite and spinel inclusions within earlier formed diopside, phlogopite and magnetite. Median 87Sr/ 86Sr values between Tertiary alkaline porphyries in the Beiya area and the western Yunnan and Tertiary basalt in the western Yunnan indicate that the Beiya lamprophyre melts were derivative and resulted from the mixing between basic melts that were related to the partial melting of phenocrysts of spinel iherzolite from a mantle source. The alkaline melts originated from partial melting along the Jinshajiang subduction ductile shear zone at the contact between the buried Palaeo-Tethyan oceanic lithosphere and the upper mantle lithosphere. The alkaline melts are composed of 65% sanidine (Or 70Ab 28An 2) and 35% Si

  16. Temporal and geochemical evolution of the Cenozoic intraplate volcanism of Zealandia

    NASA Astrophysics Data System (ADS)

    Timm, Christian; Hoernle, Kaj; Werner, Reinhard; Hauff, Folkmar; den Bogaard, Paul van; White, James; Mortimer, Nick; Garbe-Schönberg, Dieter

    2010-01-01

    In order to constrain better the distribution, age, geochemistry and origin of widespread Cenozoic intraplate volcanism on Zealandia, the New Zealand micro-continent, we report new 40Ar/ 39Ar and geochemical (major and trace element and Sr-Nd-Hf-Pb isotope) data from offshore (Chatham Rise, Campbell and Challenger Plateaus) and onland (North, South, Auckland, Campbell, Chatham and Antipodes Islands of New Zealand) volcanism on Zealandia. The samples include nephelinite, basanite through phonolite, alkali basalt through trachyte/rhyolite, and minor tholeiite and basaltic andesite, all of which have ocean island basalt (OIB)-type trace element signatures and which range in age from 64.8 to 0.17 Ma. Isotope ratios show a wide range in composition ( 87Sr/ 86Sr = 0.7027-0.7050, 143Nd/ 144Nd = 0.5128-0.5131, 177Hf/ 176Hf = 0.2829-0.2831, 206Pb/ 204Pb = 18.62-20.67, 207Pb/ 204Pb = 15.54-15.72 and 208Pb/ 204Pb = 38.27-40.34) with samples plotting between mid-ocean-ridge basalts (MORB) and Cretaceous New Zealand intraplate volcanic rocks. Major characteristics of Zealandia's Cenozoic volcanism include longevity, irregular distribution and lack of age progressions in the direction of plate motion, or indeed any systematic temporal or spatial geochemical variations. We believe that these characteristics can be best explained in the context of lithospheric detachment, which causes upwelling and melting of the upper asthenospheric mantle and portions of the removed lithosphere. We propose that a large-scale seismic low-velocity anomaly, that stretches from beneath West Antarctica to Zealandia at a depth of > 600 km may represent a geochemical reservoir that has been in existence since the Cretaceous, and has been supplying the upper mantle beneath Zealandia with HIMU-type plume material throughout the Cenozoic. In addition, the sources of the Cenozoic intraplate volcanism may be at least partially derived through melting of locally detached Zealandia lower lithosphere.

  17. Geochemical and isotopic perspectives on the origin and evolution of the Siletzia Terrane.

    NASA Astrophysics Data System (ADS)

    Phillips, B. A.; Weis, D.; Mullen, E.; Kerr, A. C.

    2015-12-01

    The Siletzia terrane, located in the Cascadia forearc region of Oregon, Washington and Vancouver Island, consists of a series of accreted basaltic pillow lavas, massive flows and intrusive sheets. It represents a late Paleocene-Eocene oceanic large igneous province (LIP), previously proposed to represent an accreted oceanic plateau, hotspot island chain, backarc basin, island arc, or a sequence of slab window volcanics formed by ridge subduction. A province-wide geochemical reassessment of the terrane, including new high precision Sr-Pb-Nd-Hf isotope data on basaltic samples, has been used to assess the validity of the proposed tectonomagmatic models for Siletzia. The trace element data show REE patterns that are flat to LREE enriched with an absence of any arc signatures. These features are comparable to other oceanic plateaus such as the Ontong Java and the Caribbean and so therefore support a mantle plume origin. Initial isotope ratios range from 206Pb/204Pb = 18.869 - 19.673, 207Pb/204Pb = 15.527 - 15.609, 208Pb/204Pb = 38.551 - 39.220, ɛHf = +9.0 - 14.8, ɛNd = +5.0 - 8.0 and 87Sr/86Sr = 0.70304 - 0.70397. The isotope signatures become more varied southward across the terrane and reveal two trends: i) HIMU-DMM and ii) another extending from DMM towards the Imnaha component, thought to represent the mantle plume source of the Columbia River Basalts and Yellowstone 1,2. The data may support the previously proposed idea that the volcanism of the Siletzia terrane represents initial melting of the mantle plume head of the Yellowstone hotspot 3,4,5. Other evidence indicating a LIP origin includes the relatively rapid eruption/intrusion of an estimated magma volume of 2.6 x 106 km3 6 between ~56-49 Ma 5, which, in conjunction with our new elemental and isotopic data, indicates that the Siletzia terrane most likely represents an accreted oceanic plateau. 1. Wolff et al., (2008) Nature Geoscience 1, 177-180. 2. Jean et al., (2014) EPSL 389, 119-131 3. Duncan (1982

  18. Petrogenesis of Late Cenozoic basaltic rocks from southern Vietnam

    NASA Astrophysics Data System (ADS)

    An, A.-Rim; Choi, Sung Hi; Yu, Yongjae; Lee, Der-Chuen

    2017-02-01

    Major and trace element concentrations, and Sr-Nd-Hf-Pb isotopic compositions of Late Cenozoic (4.1 to 13.8 Ma) basaltic rocks from southern Vietnam have been determined to understand the nature of their mantle source. The volcanic rocks are composed of tholeiite basalt, alkaline basanite, trachybasalt, basaltic trachyandesite, and trachyandesite. The alkaline rocks show light rare earth element (LREE) enrichment, with (La/Yb)N = 10.3-29.8. The tholeiite basalts are distinguished by much lower values (8.8-9.5) of (La/Yb)N. On a primitive mantle-normalized trace element distribution diagram, they show oceanic island basalt (OIB)-like large-ion lithophile element enrichment without high field strength element depletion. However, some samples exhibit positive anomalies in K and Pb and negative anomalies in Sm, suggesting K-rich residual amphibole in the source. The samples contain Sr (87Sr/86Sr = 0.703794-0.704672), Nd (ɛNd = + 1.7-5.7), Hf (ɛHf = + 4.0-10.9), and Pb (206Pb/204Pb = 18.23-18.75; 207Pb/204Pb = 15.53-15.59; 208Pb/204Pb = 38.32-38.88) isotopes, plotting among OIBs, with depleted mid-ocean ridge basalt mantle-enriched mantle type 2 (DMM-EM2) characteristics. There are no discernible isotopic differences between tholeiite and the alkaline series, reflecting the same source. The Nd and Hf isotopic compositions are coupled, and plot along the mantle-crust array, ruling out the possibility of lithospheric mantle in the source. Plots of NiO against the Fo numbers of olivines from the basaltic rocks are within the range of Hainan and Hawaiian basalt olivines, implying that hybrid pyroxenite is present in the source. Also note that the estimated primary melt compositions fall within the experimental field defined by partial melting of silica-poor eclogite and peridotite. The effective melting pressure (Pf) and melting temperature (T) of the primary melts are Pf = 29.6-32.8 kbar and T = 1470-1480 °C. We suggest that Vietnamese basaltic rocks may be produced by

  19. A Coordinated Research Project on the Implementation of Nuclear Techniques to Improve Food Traceability

    NASA Astrophysics Data System (ADS)

    Frew, Russell; Cannavan, Andrew; Zandric, Zora; Maestroni, Britt; Abrahim, Aiman

    2013-04-01

    coffee, the adulteration of milk with soy protein, chemical contamination of food products, and inhomogeneity in isotopic ratios in poultry and eggs as a means to determine production history. Analytical techniques include stable isotope ratio measurements (2H/1H, 13C/12C, 15N/14N, 18O/16O, 34S/32S, 87Sr/86Sr, 208Pb/207Pb/206Pb), elemental analysis, DNA fingerprinting, fatty acid and other biomolecule profiling, chromatography-mass spectrometry and near infra-red spectroscopy.

  20. Cenozoic Bimodal Volcanic Rocks of the Northeast boundary of Tibetan Plateau: implication for the collision-induced mantle flow beneath the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yu, X.; Mo, X.; Zhao, Z.

    2011-12-01

    Cenozoic bimodal volcanic rocks of the Northeastern boundary of Tibetan Plateau are found in the area of West Qinling in China, E104°30'-105°36' and N33°35'-34°40',which located tectonically to the western boundary of Ordos block and also the north section of the N-S trending Helan mountain-Liupan mountain-Yunnan tectonic belt. The geological setting of the bimodal volcanic rocks belongs to an assemblage of Cratonic blocks composed of many small blocks linked by oroginic belts(Deng et al., 1996). The bimodal volcanic rocks, similar to those in East African rift, are consisted of kamafugite, volcanic eruption carbonatite, shoshonite, rhyolite and/or trachyte. The age of the bimodal volcanic rocks is between 23Ma to 7.1Ma according to isotopic dating of K/Ar and 39Ar/40Ar. All of these volcaic rocks in the volcanic assemblage have the characteristics rich in LREE and LIL. Not only that, the HFS, especially Nb, Zr and P in the volcanic rocks are higher than other Cenozoic alkaline volcanic rocks in Tibetan Plateau. The 87Sr/86Sr=0.704031-0.70525, 206Pb/204Pb=18.408-19.062, 207Pb/204Pb=15.476-15.677, 208Pb/204Pb=38.061-39.414 and ɛ(Nd) =0.3-5.3 of the volcanic rocks, all of these are akin to the feature of Neo-Tethyan mantle geochemical end member as represented by Yaluzangbu ophiolites defined by Zhao and Mo et al (2009), and also akin to the volcanic rocks related to Ontong Java and FOZO mantle plum(Yu et al.,2009). Cenozoic bimodal volcanic rocks in Western Qinling, Northeastern boundary of Tibetan Plateau provide ideal lithoprobes for understanding of the mantle beneath Tibetan Plateau and showed that the Cenozoic bimodal volcanic rocks bear the geochemical feature of Indian ocean mantle domain, and its genesis may be related to mantle plum, the magmatic source of the bimodal volcanic rocks should be a depleted mantle. For this reason, we suggest the bimodal volcaic rock is a rifting magmatisim, and its origin and genesis of the bimodal volcaic rocks of

  1. A Coast Mountains provenance for the Valdez and Orca groups, southern Alaska, based on Nd, Sr, and Pb isotopic evidence

    USGS Publications Warehouse

    Farmer, G.L.; Ayuso, R.; Plafker, G.

    1993-01-01

    Nd, Sr, and Pb isotopic data were obtained for fourteen fine- to coarse-grained samples of accreted flysch of the Late Cretaceous and early Tertiary Valdez and Orca Groups in southern Alaska to determine the flysch provenance. Argillites and greywackes from the Orca Group, as well as compositionally similar but higher metamorphic grade rocks from the Valdez Group, show a restricted range of correlated ??{lunate}Nd ( -0.6 to -3.8) and 87Sr 86Sr (0.7060-0.7080) at the time of sediment deposition ( ??? 50 Ma). Pb isotopic compositions also vary over a narrow range ( 206Pb 204Pb = 19.138-19.395, 207Pb 204Pb = 15.593-15.703, 208Pb 204Pb = 38.677-39.209), and in the Orca Group the samples generally become more radiogenic with decreasing ??{lunate}Nd and increasing 87Sr 86Sr. All samples have similar trace element compositions characterized by moderate light rare earth element enrichments, and low ratios of high field strength elements to large ion lithophile elements. Based on petrographic, geochemical, and isotopic data the sedimentary rocks are interpreted to have been derived largely from a Phanerozoic continental margin arc complex characterized by igneous rocks with ??{lunate}Nd values between 0 and -5. The latter conclusion is supported by the ??{lunate}Nd values of a tonalite clast and a rhyodacite clast in the Orca Group (??{lunate}Nd = -4.9 and -0.9, respectively). However, trondjemitic clasts in the Orca Group have significantly lower ??{lunate}Nd ( ??? -10) and require a derivation of a portion of the flysch from Precambrian crustal sources. The Nd, Sr, and Pb isotopic compositions of both the Valdez and Orca Groups overlap the values determined for intrusive igneous rocks exposed within the northern portion of the Late Cretaceous to early Tertiary Coast Mountains Plutonic Complex in western British Columbia and equivalent rocks in southeastern Alaska. The isotopic data support previous conclusions based on geologic studies which suggest that the flysch was

  2. Geochronology and geochemistry of Eocene potassic felsic intrusions in the Nangqian basin, eastern Tibet: Tectonic and metallogenic implications

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Bi, Xian-Wu; Hu, Rui-Zhong; Chen, You-wei; Liu, He-qing; Xu, Lei-luo

    2016-03-01

    The Jinshajiang-Ailaoshan copper belt is the most significant porphyry copper belt in eastern Tibet. In the northern segment of this belt within the Nangqian basin, which occurs 100 km east of the Yulong porphyry copper deposit, several felsic intrusions have been recently discovered. The Yulong porphyry copper deposit is one of the largest porphyry copper deposits in China, and it is associated with peraluminous adakitic rocks formed in a post-collisional setting. The Nangqian felsic intrusions vary from syenite porphyry to monzonite porphyry in rock types. No significant Cu-Au mineralization has been found in the Nangqian felsic intrusions despite extensive exploration in recent years. LA-ICP-MS zircon U-Pb dating reveals that the Nangqian syenite porphyry and monzonite porphyry were emplaced at 35.6±0.3 Ma and from 39.5±0.3 to 37.4±0.3 Ma, respectively, similar to the age of the Yulong porphyry copper deposit. The Nangqian felsic intrusions are characterized by metaluminous compositions (A/CNK = 0.82-1.01), and they share some common features with shoshonites such as high K2O contents (4.58-5.58 wt.%), high K2O/Na2O ratios (0.92-1.28), LREE-LILE enrichments and negative Nb-Ta-Ti-P anomalies, as well as with adakites derived from an eclogite-facies source with high Al2O3 (14.98-15.74 wt.%), Sr (954-2190 ppm), Sr/Y (68-132) and La/Yb (53-85), and low Y and Yb contents. The Nangqian felsic intrusions have high initial 87Sr/86Sr (0.7050-0.7055), variable εNd(t) (- 0.31-1.43) and small variations in (206Pb/204Pb)i (18.68-18.74), (207Pb/204Pb)i (15.53-15.62) and (208Pb/204Pb)i (38.51-38.80). Zircon crystals from both syenite and monzonite porphyries are characterized by positive εHf(t) from 5.2 to 8.5. The results suggest that the syenite and monzonite magmas were differentiated from parental shoshonitic melts by fractional crystallization of olivine, clinopyroxene and minor feldspar. The parent magmas originated from a lithospheric mantle metasomatized by slab

  3. Zircon U-Pb dating, geochemistry and Sr-Nd-Pb-Hf isotopes of the Wajilitag alkali mafic dikes, and associated diorite and syenitic rocks: Implications for magmatic evolution of the Tarim large igneous province

    NASA Astrophysics Data System (ADS)

    Zou, Si-Yuan; Li, Zi-Long; Song, Biao; Ernst, Richard E.; Li, Yin-Qi; Ren, Zhong-Yuan; Yang, Shu-Feng; Chen, Han-Lin; Xu, Yi-Gang; Song, Xie-Yan

    2015-01-01

    The Early Permian Tarim large igneous province (Tarim LIP) consists mainly of basaltic lavas, mafic-ultramafic intrusions including dikes and, syenite bodies in the Tarim Basin, NW China. A major unit of the Tarim LIP, the Wajilitag intrusive complex, consists of olivine pyroxenite, clinopyroxenite and gabbro units (from bottom to top), diorite and syenite rocks occurred in the upper part of the complex and alkali mafic dikes intrude the clinopyroxenite phase. Here we report the zircon U-Pb age and Hf isotopes, geochemical characteristics and Sr-Nd-Pb isotopic data of the alkali mafic dikes, and diorite, aegirine-nepheline syenite and syenite porphyry units in the Wajilitag intrusive complex. Zircons from the diorite and alkali mafic rocks yield concordant crystallization ages of 275.2 ± 1.2 Ma and 281.4 ± 1.7 Ma, respectively. The diorite and syenitic rocks in Wajilitag area have a narrow range of SiO2 contents (51.9-57.3 wt.%), and are enriched in total alkalis (Na2O + K2O = 8.3-14.3 wt.%), among which the aegirine-nepheline syenite and syenite porphyry have the geochemical affinity of A-type granites. The alkali mafic rocks and syenitic rocks have high Al2O3 (19.4-21.1 wt.%), Zr, Hf, Ba contents, total rare earth element abundances and LREE/HREE ratios and low Mg# value, K, P and Ti contents. Diorites have lower Al2O3 contents, total REE abundances and LREE/HREE ratios and higher Mg# values than the alkali mafic rocks and syenitic rocks. The diorites and syenitic rocks have low initial 87Sr/86Sr ratios (0.7034-0.7046), and high εNd(t) values (0.1-4.1) and zircon εHf(t) values (- 0.9-4.4). All the diorites and syenitic rocks show the 206Pb/204Pb ratios ranging of 18.0-19.5, 207Pb/204Pb of 15.4-15.6 and 208Pb/204Pb of 38.0-39.9. Sr-Nd isotopic ratios indicate a FOZO-like mantle source for the diorite and syenitic rocks, similar to that of the mafic-ultramafic rocks in the Wajilitag complex. In contrast, zircon Hf isotopes of basalt and syenite elsewhere in the

  4. Petrogenesis and origin of modern Ethiopian rift basalts: Constraints from isotope and trace element geochemistry

    NASA Astrophysics Data System (ADS)

    Ayalew, D.; Jung, S.; Romer, R. L.; Kersten, F.; Pfänder, J. A.; Garbe-Schönberg, D.

    2016-08-01

    The source of continental rift-related basalts and their relation to rifting processes is a continuous matter of debate. We present major and trace element and Sr, Nd, Hf and Pb isotope data for axial rift basalts from eight volcanic centres (Ayelu, Hertali, Dofan, Fantale, Kone, Bosetti and Gedemsa, from NE to SW) in Afar and Main Ethiopian Rift (MER) to assess their source regions and their genetic relationships. These lavas have geochemical characteristics, i.e., a peak at Ba, Nb and troughs at K and Rb in primitive mantle-normalised multielement diagrams, which are consistent with predominant melting of an amphibole-bearing lithospheric mantle. However, the isotopic compositions for these lavas are heterogeneous (87Sr/86Sr = 0.70354-0.70431, 143Nd/144Nd = 0.51280-0.51294, 176Hf/177Hf = 0.28301-0.28315, 206Pb/204Pb = 18.48-19.31, 207Pb/204Pb = 15.53-15.62, 208Pb/204Pb = 38.61-39.06) and require various mantle reservoirs with distinctive isotopic signatures. The range of isotopic compositions requires the involvement of three distinct source components from the asthenospheric and veined lithospheric mantle. Progressive rifting leads to lithosperic thinning and upwelling of hot asthenospheric mantle, which induces melting of the veined lithospheric mantle. The trace element characteristics of the lavas are dominated by the vein material, which has a higher trace element content than the surrounding mantle. The isotopic composition of the vein material, however, is not very different from the ambient mantle, giving rise of apparent uncoupling of trace element and isotope constraints for the melt source. The uprising basaltic liquids in part inherit a lithospheric trace element signature, while their isotopic compositions are mostly unaffected due to short residence times within the lithosphere in context with progressive rifting and lithospheric thinning. Thus, the geochemical and isotope data are consistent with a multi-component source prevailing beneath the Afar

  5. Late Paleozoic crustal history of central coastal Queensland interpreted from geochemistry of Mesozoic plutons: The effects of continental rifting

    NASA Astrophysics Data System (ADS)

    Allen, C. M.; Wooden, J. L.; Chappell, B. W.

    1997-12-01

    The eastern margin of Australia is understood to be the result of continental rifting during the Cretaceous and Tertiary. Consistent with this model, Cretaceous igneous rocks (granites to basalts) in a continental marginal setting near Bowen, Queensland are isotonically retarded, having isotopic ratios similar to those of most island arcs (Sr1 = 0.7030-0.7039, ɛNd = +6.46 to +3.00 and 206Pb/204Pb = 18.44-18.77, 207Pb/204Pb = 15.552-15.623, and 208Pb/204Pb = 37.90-38.52). These isotopic signatures are much less evolved than the Late Carboniferous-Permian batholith that many Cretaceous plutons intrude. As rocks ranging in age from about 300-100 Ma are well exposed near Bowen, we can track magma evolution through time. The significant change of magma source occurred much earlier than the Cretaceous based on the fact that Triassic granites in the same area are also isotonically primitive. We attribute the changes of magma composition to crustal rifting during the Late Permian and earliest Triassic. The Cretaceous rocks (actually latest Jurassic to Cretaceous, 145-98 Ma) themselves show compositional trends with time. Rocks of appropriate mineralogy for Al-in-hornblende geobarometry yield pressures ranging from 250 to 80 MPa for rocks ranging in age from 145 to 125 Ma, respectively. More significantly, this older group is relatively compositionally restricted, and is Sr-rich, and Y- and Zr-poor compared to 120-98 Ma rocks. This younger groups is bimodal, being comprised principally of basalts and rhyolites (granites). REE patterns for a given rock type, however, do not differ with age tribute these relatively subtle trace element differences to small differences in conditions (T, aH2O) at the site of melting. Cretaceous crustal rifting can explain the range of rock types and the spatial distribution of rocks < 120 Ma in a longitudinal strip between and overlapping with provinces of older Cretaceous intrusions. A subduction-related setting is assigned to the 145-125 Ma

  6. Late Paleozoic crustal history of central coastal Queensland interpreted from geochemistry of Mesozoic plutons: The effects of continental rifting

    USGS Publications Warehouse

    Allen, C.M.; Wooden, J.L.; Chappell, B.W.

    1997-01-01

    The eastern margin of Australia is understood to be the result of continental rifting during the Cretaceous and Tertiary. Consistent with this model, Cretaceous igneous rocks (granites to basalts) in a continental marginal setting near Bowen, Queensland are isotonically retarded, having isotopic ratios similar to those of most island arcs (Sri = 0.7030-0.7039, ??Nd = +6.46 to +3.00 and 206Pb/204Pb = 18.44-18.77, 207Pb/204Pb = 15.552-15.623, and 208Pb/204Pb = 37.90-38.52). These isotopic signatures are much less evolved than the Late Carboniferous-Permian batholith that many Cretaceous plutons intrude. As rocks ranging in age from about 300-100 Ma are well exposed near Bowen, we can track magma evolution through time. The significant change of magma source occurred much earlier than the Cretaceous based on the fact that Triassic granites in the same area are also isotonically primitive. We attribute the changes of magma composition to crustal rifting during the Late Permian and earliest Triassic. The Cretaceous rocks (actually latest Jurassic to Cretaceous, 145-98 Ma) themselves show compositional trends with time. Rocks of appropriate mineralogy for Al-in-hornblende geobarometry yield pressures ranging from 250 to 80 MPa for rocks ranging in age from 145 to 125 Ma, respectively. More significantly, this older group is relatively compositionally restricted, and is Sr-rich, and Y- and Zr-poor compared to 120-98 Ma rocks. This younger groups is bimodal, being comprised principally of basalts and rhyolites (granites). REE patterns for a given rock type, however, do not differ with age tribute these relatively subtle trace element differences to small differences in conditions (T, aH2O) at the site of melting. Cretaceous crustal rifting can explain the range of rock types and the spatial distribution of rocks < 120 Ma in a longitudinal strip between and overlapping with provinces of older Cretaceous intrusions. A subduction-related setting is assigned to the 145-125 Ma

  7. Late Permian basalts in the Yanghe area, eastern Sichuan Province, SW China: Implications for the geodynamics of the Emeishan flood basalt province and Permian global mass extinction

    NASA Astrophysics Data System (ADS)

    Li, Hongbo; Zhang, Zhaochong; Santosh, M.; Lü, Linsu; Han, Liu; Liu, Wei

    2017-02-01

    We report the finding of a ∼20 m thick sequence of massive pyroxene-plagioclase-phyric basalt lava flows in the Yanghe area of the northeastern Sichuan Basin, within the Yangtze craton of SW China, which were previously considered to be located outside the Emeishan flood basalt province. This basaltic sequence above the middle Permian Maokou Formation (Fm.) is overlain by the late Permian Longtan Fm. Thus, the Yanghe basalts should be stratigraphically correlated with the Emeishan flood basalts. The Yanghe basalts show typical oceanic island basalt (OIB) affinity, and geochemically resemble Emeishan basalts, especially in the case of high-Ti (HT) basalts from the eastern domain of the Emeishan flood basalt province. The rocks have low age-corrected (87Sr/86Sr)t (t = 260 Ma) ratios (0.704158-0.704929) and Pb isotopic ratios [206Pb/204Pb(t) (18.264-18.524), 207Pb/204Pb(t) (15.543-15.58), and 208Pb/204Pb(t) (38.147-38.519)], and positive εNd(t) values (+3.15 to +3.61), suggesting that the lavas have not undergone any significant crustal contamination. The crystallization temperature of clinopyroxene is estimated to be 1368-1420 °C, suggesting anomalously thermal inputs from a mantle source and a possible plume-head origin. The fractionation of middle rare earth elements (MREE) to heavy REE (HREE) suggests that these rocks were produced by small degrees of partial melting of mantle peridotite within the garnet-spinel transition region. The stratigraphic relationships and similar geochemical signatures with the Emeishan flood basalts suggest that the Yanghe basalts are part of the Emeishan flood basalt province and can be considered as the northeastern limit of the Emeishan flood basalt province. Our finding extends the diameter of the Emeishan flood basalt province to ∼1200-1400 km, covering an area of up to ∼7 × 105 km2, two times more than previously estimated. The larger areal extent and giant eruption volume, incorporating the Sichuan Basin, lend support

  8. Heavy metal input to agricultural soils from irrigation with treated wastewater: Insight from Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kloppmann, Wolfram; Cary, Lise; Psarras, Georgios; Surdyk, Nicolas; Chartzoulakis, Kostas; Pettenati, Marie; Maton, Laure

    2010-05-01

    A major objective of the EU FP6 project SAFIR was to overcome certain drawbacks of wastewater reuse through the development of a new irrigation technology combining small-scale modular water treatment plants on farm level and improved irrigation hardware, in the aim to lower the risks related to low quality water and to increase water use efficiency. This innovative technology was tested in several hydro-climatic contexts (Crete, Italy, Serbia, China) on experimental irrigated tomato and potato fields. Here we present the heavy metal variations in soil after medium-term (3 irrigation seasons from 2006-2008) use of treated municipal wastewater with a special focus on lead and lead isotope signatures. The experimental site is located in Chania, Crete. A matrix of plots were irrigated, combining different water qualities (secondary, primary treated wastewater, tap water, partially spiked with heavy metals, going through newly developed tertiary treatment systems) with different irrigation strategies (surface and subsurface drip irrigation combined with full irrigation and partial root drying). In order to assess small scale heavy metal distribution around a drip emitter, Pb isotope tracing was used, combined with selective extraction. The sampling for Pb isotope fingerprinting was performed after the 3rd season of ww-irrigation on a lateral profile from a drip irrigator (half distance between drip lines, i.e. 50cm) and three depth intervals (0-10, 10-20, 20-40 cm). These samples were lixiviated through a 3 step selective extraction procedure giving rise to the bio-accessible, mobile and residual fraction: CaCl2/NaNO3 (bio-accessible fraction), DPTA (mobile fraction), total acid attack (residual fraction). Those samples were analysed for trace elements (including heavy metals) and major inorganic compounds by ICP-MS. The extracted fractions were then analysed by Thermal Ionisation Mass Spectrometry (TIMS) for their lead isotope fingerprints (204Pb, 206Pb, 207Pb, 208Pb

  9. Sm-Nd dating and REE Composition of scheelite for the Honghuaerji scheelite deposit, Inner Mongolia, Northeast China

    NASA Astrophysics Data System (ADS)

    Guo, Zhijun; Li, Jinwen; Xu, Xinying; Song, Zeyou; Dong, Xuzhou; Tian, Jing; Yang, Yuncheng; She, Hongquan; Xiang, Anping; Kang, Yongjian

    2016-09-01

    Sm-Nd analyses of seven scheelite samples from scheelite-quartz veins in the Honghuaerji scheelite deposit produce a well-defined linear array on an isochron diagram with a mean square weighted deviation (MSWD) of 0.87 corresponding to an age of 178.4 ± 2.9 Ma with εNd(t) = + 1.50. This age is interpreted to represent the age of scheelite mineralization. The scheelite Sm-Nd age is in good agreement with U-Pb ages obtained from a mineralization-related granite (179.4 178.6 Ma), indicating that there is no apparent age gap between granite crystallization and ore formation. Rare earth element (REE) abundances in the scheelite were determined by in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and the scheelite samples contain elevated REE concentrations with total ΣREE + Y contents in the range of 3339 to 6321 ppm. The chondrite-normalized REE distribution patterns of all scheelites are middle REE (MREE)-enriched, with strong negative Eu-anomalies (Eu/Eu* = 0.09 0.23). The REE characteristics of the Honghuaerji scheelite suggest that REE3 + substituted into the Ca site along with Na and Nb (dominated by Na), whereas Eu is predominantly present as Eu2 + in the scheelite and may have crystallized from relatively reduced fluids. All sulfur isotope data (δ34S) for sulfide separates range from + 2.0 to + 3.8‰, with an average of 3.2‰. Measured 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios vary from 18.243 to 18.451, 15.494 to 15.574, and 37.933 to 38.340, respectively. On the basis of common Sr-Nd-Pb-Hf isotopic characteristics between the scheelite and the host granite and the positive initial Nd isotope ratios (+ 1.46 - + 1.52), low 87Sr/86Sr ratios (0.704983-0.705297) in the scheelites, it is inferred that the hydrothermal fluids responsible for tungsten mineralization at Honghuaerji were of magmatic origin with a mantle-derived signature. Based on the regional geology, tectonic evolution, and geochemical evidence, the

  10. Magmas with slab fluid and decompression melting signatures coexisting in the Gulf of Fonseca: Evidence from Isla El Tigre volcano (Honduras, Central America)

    NASA Astrophysics Data System (ADS)

    Mattioli, Michele; Renzulli, Alberto; Agostini, Samuele; Lucidi, Roberto

    2016-01-01

    Isla El Tigre volcano is located in the Gulf of Fonseca (Honduras) along the Central America volcanic front, where a significant change in the strike of the volcanic chain is observed. The studied samples of this poorly investigated volcano are mainly subalkaline basic to intermediate lavas (basalts and basaltic andesites) and subordinate subalkaline/alkaline transitional basalts, both having the typical mineralogical and geochemical characteristics of arc volcanic rocks. On the basis of petrographic and geochemical features, two groups of rocks have been distinguished. Lavas from the main volcanic edifice are highly porphyritic and hy-qz normative, and have lower MgO contents (< 5 wt.%). They show significant LILE and LREE enrichments and Nb-Ta depletions, and have a strong slab signature as well as incompatible element contents similar to those of the main front of the adjacent volcanoes in El Salvador and Nicaragua (e.g., Ba/La up to 80). In contrast, lavas from the parasitic cones have higher MgO contents (> 5 wt.%), are ol-hy normative and show lower HFSE depletions relative to LILE and LREE, with lower Ba/La, Ba/Nb and Zr/Nb ratios. This suggests that mantle-derived magmas were not produced by the same process throughout the activity of the volcano. The bulk rock geochemistry and 87Sr/86Sr (0.70373-0.70382), 143Nd/144Nd (0.51298-0.51301), 206Pb/204Pb (18.55-18.58), 207Pb/204Pb (15.54-15.56) and 208Pb/204Pb (38.23-38.26) isotopic data of Isla El Tigre compared with the other volcanoes of the Gulf of Fonseca and all available literature data for Central America suggests that this stratovolcano was mainly built by mantle-derived melts driven by slab-derived fluid-flux melting, while magmas erupted through its parasitic cones have a clear signature of decompression melting with minor slab contribution. The coexistence of these two different mantle melting generation processes is likely related to the complex geodynamic setting of the Gulf of Fonseca, where the

  11. Zircon U-Pb ages, geochemical and Sr-Nd-Pb-Hf isotopic constraints on petrogenesis of the Tarom-Olya pluton, Alborz magmatic belt, NW Iran

    NASA Astrophysics Data System (ADS)

    Nabatian, Ghasem; Jiang, Shao-Yong; Honarmand, Maryam; Neubauer, Franz

    2016-02-01

    A petrological, geochemical and Sr-Nd-Pb isotopic study was carried out on the Tarom-Olya pluton, Iran, in the central part of the Alpine-Himalayan orogenic belt. The pluton is composed of diorite, monzonite, quartz-monzonite and monzogranite, which form part of the Western Alborz magmatic belt. LA-ICP-MS analyses of zircons yield ages from 35.7 ± 0.8 Ma to 37.7 ± 0.5 Ma, interpreted as the ages of crystallization of magmas. Rocks from the pluton have SiO2 contents ranging from 57.0 to 69.9 wt.%, high K2O + Na2O (5.5 to 10.3 wt.%) and K2O/Na2O ratio of 0.9 to 2.0. Geochemical discrimination criteria show I-type and shoshonitic features for the studied rocks. All investigated rocks are enriched in light rare earth elements (LREEs), large ion lithophile elements (LILEs), depleted in high-field strength elements (HFSEs), and show weak or insignificant Eu anomalies (Eu/Eu* = 0.57-1.02) in chondrite-normalized trace element patterns. The Tarom-Olya pluton samples also show depletions in Nb, Ta and Ti typical of subduction-related arc magmatic signatures. The samples have relatively low ISr (0.7047-0.7051) and positive εNd(36 Ma) (+ 0.39 to + 2.10) values. The Pb isotopic ratios show a (206Pb/204Pb)i ratio of 18.49-18.67, (207Pb/204Pb)i ratio of 15.58-15.61 and (208Pb/204Pb)i ratio of 38.33-38.77. The εHf(t) values of the Tarom-Olya pluton zircons vary from - 5.9 to + 8.4, with a peak at + 2 to + 4. The depleted mantle Hf model ages for the Tarom-Olya samples are close to 600 Ma. These isotope evidences indicate contribution of juvenile sources in petrogenesis of the Tarom-Olya pluton. Geochemical and isotopic data suggest that the parental magma of the Tarom-Olya pluton was mainly derived from a sub-continental lithospheric mantle source, which was metasomatized by fluids and melts from the subducted Neotethyan slab with a minor crustal contribution. Subsequent hot asthenospheric upwelling and lithospheric extension caused decompression melting in the final stage of

  12. Geology, geochemistry and genesis of the Eocene Lailishan Sn deposit in the Sanjiang region, SW China

    NASA Astrophysics Data System (ADS)

    Cao, Hua-Wen; Pei, Qiu-Ming; Zhang, Shou-Ting; Zhang, Lin-Kui; Tang, Li; Lin, Jin-Zhan; Zheng, Luo

    2017-04-01

    The Lailishan deposit is an important tin deposit that is genetically associated with an Early Eocene biotite granite in the western Yunnan metallogenic belt in the Sanjiang region, SW China. This study reports new zircon U-Pb ages and Hf isotopic data, whole-rock elements, mica Ar-Ar age and C-H-O-S-Pb isotope for the Lailishan Sn deposit. The mineralization-related biotite granite crystallized during the Early Eocene (50.5 Ma), with its zircon εHf(t) values ranging from -11.5 to -7.6 and two-stage Hf model ages (TDM2) ranging from 1.60 to 1.85 Ga. The rocks are peraluminous with A/CNK values of 0.99-1.08. The granites display high Si, Al and K contents but low Mg, Fe and Ca contents. The rocks show flat chondrite-normalized REE patterns with strong Eu negative anomalies. These characteristics indicate that the magma originated from a continental crustal source. The hydrothermal muscovite exhibits an Ar-Ar plateau age of 50.4 ± 0.2 Ma. The δ18O and δD values of hydrothermal quartz from the deposit range from -7.32‰ to 4.01‰ and from -124.9‰ to -87.1‰, respectively. The δ13CPDB and δ18OSMOW values of calcite range from -11.3‰ to -3.7‰ and from +2.2‰ to +12.7‰, respectively. The sulfur isotopic compositions (δ34SV-CDT) range from +3.3‰ to +8.6‰ for sulfide separates, and the lead isotopic ratios 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb range from 18.668 to 18.746, from 15.710 to 15.743 and from 39.202 to 39.295, respectively. These isotopic compositions are similar to those of magma-derived fluids, indicating that the ore-forming fluids and materials mainly originated from magmatic rocks with some input from meteoric water. This evidence suggests that the tin mineralization is closely linked to the Lailishan I-type granites. In combination with previous data, it is proposed in this study that widespread early Eocene magmatism resulted from the slab breakoff of the subducting Neo-Tethyan slab at ca. 55 Ma.

  13. Sr-Nd-Hf-Pb isotopic constraints on the origin of silicic lavas in the northern Cascade Arc

    NASA Astrophysics Data System (ADS)

    Martindale, M.; Mullen, E.; Weis, D.

    2015-12-01

    The Cascade Arc is the type-locality for a 'hot' subduction zone, where the downgoing slab is young and subduction is relatively slow; a unique setting for studying the controls on silicic (>56 wt% SiO2) magma genesis [1,2]. We present high precision Sr-Nd-Hf-Pb isotopic and trace element data for silicic lavas and country rocks from the major centres of the Garibaldi Volcanic Belt (GVB) in British Columbia, which are hosted by the Mesozoic Coast Plutonic Complex and accreted Coast Belt terranes. In isotopic plots, the silicic GVB lavas define mixing curves between northern Cascadia Basin sediment [3] and Juan de Fuca MORB. The silicic GVB lavas have lower ɛNd, and higher ɛHf, 87Sr/86Sr, 208Pb/204Pb and 207Pb/204Pb for a given 206Pb/204Pb than co-existing alkalic mafic lavas [2,4] which define a separate isotopic cluster. The alkalic mafic lavas have OIB-like trace element compositions [2,4], but the silicic lavas are calc-alkaline with a typical 'arc' trace element signature. Geochemical systematics suggest that a mafic, isotopically 'depleted' contaminant may be affecting the composition of GVB silicic lavas. However, modelling indicates that slab melts do not constitute a major component of the lavas despite high slab temperatures. Geochemical models also rule out the accreted Coast Belt terranes as an assimilant. However, AFC modelling using 147 Ma Cloudburst quartz diorite [5] as the assimilant can explain both the trace element and isotopic compositional range displayed by GVB silicic magmas, consistent with the Coast Plutonic Complex as a major component of the deep crust in this region. Crustal assimilation would have partially overprinted any alkalic mantle-derived signature of parental magmas, while imparting a calc-alkaline arc signature to resulting silicic magmas. [1] Green & Harry (1999) EPSL, 171; [2] Mullen & Weis (2013) G3, 14; [3] Carpentier et al. (2014) Chem Geol, 382; [4] Mullen & Weis (2015) EPSL, 414; [5] Friedman & Armstrong (1995) GSA

  14. Provenance of the late Proterozoic to early Cambrian metaclastic sediments of the Sierra de San Luis (Eastern Sierras Pampeanas) and Cordillera Oriental, Argentina

    NASA Astrophysics Data System (ADS)

    Drobe, Malte; López de Luchi, Mónica G.; Steenken, André; Frei, Robert; Naumann, Rudolf; Siegesmund, Siegfried; Wemmer, Klaus

    2009-10-01

    Provenance studies have been performed utilising major and trace elements, Nd systematics, whole rock Pb-Pb isotopes and zircon U/Pb SHRIMP data on metasedimentary rocks of the Sierra de San Luis (Nogolí Metamorphic Complex, Pringles Metamorphic Complex, Conlara Metamorphic Complex and San Luis Formation) and the Puncoviscana Formation of the Cordillera Oriental. The goal was the characterisation of the different domains in the study area and to give insights to the location of the source rocks. An active continental margin setting with typical composition of the upper continental crust is depicted for all the complexes using major and trace elements. The Pringles Metamorphic Complex shows indications for crustal recycling, pointing to a bimodal provenance. Major volcanic input has to be rejected due to Th/Sc, Y/Ni and Cr/V ratios for all units. The ɛNd (540 Ma) data is lower for the San Luis Formation and higher for the Conlara Metamorphic Complex, as compared to the other units, in which a good consistency is given. This is similar to the TDM ages, where the metapsammitic samples of the San Luis Formation are slightly older. The spread of data is largest for the Pringles Metamorphic Complex, again implying two different sources. The whole rock 207Pb/ 206Pb isotopic data lies in between the South American and African sources, excluding Laurentian provenances. The whole rock Pb-Pb data is almost indistinguishable in the different investigated domains. Only the PMC shows slightly elevated 208Pb/ 204Pb values. Possible source rocks for the different domains could be the Quebrada Choja in the Central Arequipa-Antofalla domain, the Southern domain of the Arequipa-Antofalla basement, the Brazilian shield or southern Africa. Zircon SHRIMP data point to a connection between the Puncoviscana Formation and the Conlara Metamorphic Complex. Two maxima around 600 Ma and around 1000 Ma have been determined. The Nogolí Metamorphic Complex and the Pringles Metamorphic Complex

  15. Lead isotopes in North Pacific deep water - Implications for past changes in input sources and circulation patterns

    USGS Publications Warehouse

    van de Flierdt, T.; Frank, M.; Halliday, A.N.; Hein, J.R.; Hattendorf, B.; Gunther, D.; Kubik, P.W.

    2003-01-01

    The sources of non-anthropogenic Pb in seawater have been the subject of debate. Here we present Pb isotope time-series that indicate that the non-anthropogenic Pb budget of the northernmost Pacific Ocean has been governed by ocean circulation and riverine inputs, which in turn have ultimately been controlled by tectonic processes. Despite the fact that the investigated locations are situated within the Asian dust plume, and proximal to extensive arc volcanism, eolian contributions have had little impact. We have obtained the first high-resolution and high-precision Pb isotope time-series of North Pacific deep water from two ferromanganese crusts from the Gulf of Alaska in the NE Pacific Ocean, and from the Detroit Seamount in the NW Pacific Ocean. Both crusts were dated applying 10 Be/9Be ratios and yield continuous time-series for the past 13.5 and 9.6 Myr, respectively. Lead isotopes show a monotonic evolution in 206Pb/204Pb from low values in the Miocene (??? 18.57) to high values at present day (??? 18.84) in both crusts, even though they are separated by more than 3000 km along the Aleutian Arc. The variation exceeds the amplitude found in Equatorial Pacific deep water records by about three-fold. There also is a striking similarity in 207Pb/204Pb and 208Pb/ 204Pb ratios of the two crusts, indicating the existence of a local circulation cell in the sub-polar North Pacific, where efficient lateral mixing has taken place but only limited exchange (in terms of Pb) with deep water from the Equatorial Pacific has occurred. Both crusts display well-defined trends with age in Pb-Pb isotope mixing plots, which require the involvement of at least four distinct Pb sources for North Pacific deep water. The Pb isotope time-series reveal that eolian supplies (volcanic ash and continent-derived loess) have only been of minor importance for the dissolved Pb budget of marginal sites in the deep North Pacific over the past 6 Myr. The two predominant sources have been young

  16. Genesis of the Bangbule Pb-Zn-Cu polymetallic deposit in Tibet, western China: Evidence from zircon U-Pb geochronology and S-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kan, Tian; Zheng, Youye; Gao, Shunbao

    2016-04-01

    The Banbule Pb-Zn-Cu skarn deposit is located in the Longger-Gongbujiangda volcanic magma arc in the Gangdese-Nyainqentanglha Plate. It is the only lead-zinc polymetallic deposit discovered in the westernmost Nyainqentanglha metallogenic belt. The measured and indicated resources include 0.9 Mt of Pb+Zn (4.77% Pb and 4.74% Zn, respectively), 6499 t of Cu, and 178 t of Ag (18.75g/t Ag). The orebodies mainly occur as lenses, veins and irregular shapes in the contact zone between the quartz-porphyry and limestone of the Upper Permian Xiala Formation, or in the boundaries between limestone and sandstone. Pb-Zn-Cu mineralization in the Banbule deposit is closely associated with skarns. The ore minerals are dominated by galena, sphalerite, chalcopyrite, bornite, and magnetite, with subordinate pyrite, malachite, and azurite. The gangue minerals are mainly garnet, actinolite, diopside, quartz, and calcite. The ore-related quartz-porphyry displays LA-ICP-MS zircon U-Pb age of 77.31±0.74 Ma. The δ34S values of sulfides define a narrow range of -0.8 to 4.7‰ indicating a magmatic source for the ore-forming materials. Lead isotopic systematics yield 206Pb/204Pb of 18.698 to 18.752, 207Pb/204Pb of 15.696 to 15.760, and 208Pb/204Pb of 39.097 to 39.320. The data points are constrained around the growth curves of upper crust and orogenic belt according to the tectonic discrimination diagrams. The calculated Δβ - Δγ values plot within the magmatic field according to the discrimination diagram of Zhu et al. (1995). The S-Pb isotopic data suggest that Bangbule is a typical skarn deposit, and the Pb-Zn-Cu mineralization is genetically related to the quartz-porphyry in the mining district. The discovery of the Bangbule deposit indicates that there is metallogenic potential in the westernmost Nyainqentanglha belt, which is of great importance for the exploration work in this area.

  17. Lead isotopes in North Pacific deep water - implications for past changes in input sources and circulation patterns

    NASA Astrophysics Data System (ADS)

    van de Flierdt, Tina; Frank, Martin; Halliday, Alex N.; Hein, James R.; Hattendorf, Bodo; Günther, Detlef; Kubik, Peter W.

    2003-04-01

    The sources of non-anthropogenic Pb in seawater have been the subject of debate. Here we present Pb isotope time-series that indicate that the non-anthropogenic Pb budget of the northernmost Pacific Ocean has been governed by ocean circulation and riverine inputs, which in turn have ultimately been controlled by tectonic processes. Despite the fact that the investigated locations are situated within the Asian dust plume, and proximal to extensive arc volcanism, eolian contributions have had little impact. We have obtained the first high-resolution and high-precision Pb isotope time-series of North Pacific deep water from two ferromanganese crusts from the Gulf of Alaska in the NE Pacific Ocean, and from the Detroit Seamount in the NW Pacific Ocean. Both crusts were dated applying 10Be/ 9Be ratios and yield continuous time-series for the past 13.5 and 9.6 Myr, respectively. Lead isotopes show a monotonic evolution in 206Pb/ 204Pb from low values in the Miocene (≤18.57) to high values at present day (≥18.84) in both crusts, even though they are separated by more than 3000 km along the Aleutian Arc. The variation exceeds the amplitude found in Equatorial Pacific deep water records by about three-fold. There also is a striking similarity in 207Pb/ 204Pb and 208Pb/ 204Pb ratios of the two crusts, indicating the existence of a local circulation cell in the sub-polar North Pacific, where efficient lateral mixing has taken place but only limited exchange (in terms of Pb) with deep water from the Equatorial Pacific has occurred. Both crusts display well-defined trends with age in Pb-Pb isotope mixing plots, which require the involvement of at least four distinct Pb sources for North Pacific deep water. The Pb isotope time-series reveal that eolian supplies (volcanic ash and continent-derived loess) have only been of minor importance for the dissolved Pb budget of marginal sites in the deep North Pacific over the past 6 Myr. The two predominant sources have been young

  18. The geology and petrology of Volcán San Juan (Nayarit, México) and the compositionally zoned Tepic Pumice

    NASA Astrophysics Data System (ADS)

    Luhr, James F.

    2000-01-01

    Pb, 207Pb/ 204Pb, and 208Pb/ 204Pb, and low ɛNd values compared to these other volcanoes, which appear to reflect significant crustal contamination of San Juan's magmas.

  19. Copper and lead isotopic and metallic pollution record in soils from the Kombat mining area, Namibia

    NASA Astrophysics Data System (ADS)

    Mihaljevic, Martin; Ettler, Vojtech; Vanek, Ales; Chrastny, Vladislav; Kribek, Bohdan; Penizek, Vit; Sracek, Ondrej

    2013-04-01

    Copper (Cu) and lead (Pb) concentration, isotopic composition (206Pb/207Pb, 65Cu/63Cu) and speciation were studied in soils from the Kombat mining area. The Cu and Pb concentrations in the studied soils ranged between 21 mg/kg - 757 mg/kg, and 19 mg/kg - 815 mg/kg respectively. In the sequential extractions, the largest part of soil Cu appeared in the residual and reducible fractions and Pb was predominantly bound in reducible and residual fractions and was more mobile compared to Cu. Copper and Pb concentration are higher in soils close to the slime deposit. Concentration of both metals increased with increasing soil depth in irrigated and cultivated soils. In soils not contaminated by dust eroded from the slime deposit, Cu and Pb contents are not dependent on the soil depth. The Pb isotopic signatures (206Pb/207Pb) ranged between 1.15 - 1.21 in soils from the Kombat area. In most of soil samples, surface horizons exhibited lower 206Pb/207Pb ratio, which originates from the slime dust pollution (206Pb/207Pb ~ 1.15) compared to deeper soil horizons, with lithogenic Pb signatures (206Pb/207Pb > 1.2). Isotopic composition of Cu differs on contaminated and uncontaminated sites and cultivated and non-cultivated sites. The δ65Cu in the studied soil horizon ranged between -0.373 ‰ and 0.561 ‰. The most pronounced variations occurred in contaminated non cultivated and non-irrigated soils (0.529 ‰). The contaminated top horizons are enriched in isotopically heavier Cu (tailing materials), and δ65Cu decreased with depth. Irrigated (cultivated) and contaminated soils exhibited heavier Cu in the surface horizons (originated from tailing dust δ65Cu = 0.260), decrease of δ65Cu in Bt horizons (biological uptake of light isotope by crop, and their incorporation in this horizons) and increase of δ65Cu in Bc horizons. The Bc horizons of cultivated and irrigated Phaeozems are enriched in Mn nodules (0.2 - 1.5 cm diameter, prevailing Mn phase pyrochroite Mn(OH)2) which

  20. Isotope exchange between natural and anthropogenic Pb in the coastal waters of Singapore: exchange experiment, Kd model, and implications for the interpretation of coastal 210Pb data

    NASA Astrophysics Data System (ADS)

    Boyle, E. A.; Chen, M.; Zurbrick, C.; Carrasco, G. G.

    2015-12-01

    Observations from annually-banded corals and seawater samples show that marine lead (Pb) in the coastal waters of Singapore has an isotopic composition that does not match that of the anthropogenic aerosols in this region, unlike what is seen in most parts of the open ocean. The 206Pb/207Pb composition of Singaporean marine Pb is 1.18-1.20 whereas the local aerosols are 1.14-1.16. In order to explore this discrepancy further, we collected a large volume water from the Johor River estuary (flowing from Malaysia to the northern border of Singapore), added a distinct isotope spike (NBS981, 206Pb/207Pb =1.093) to an unfiltered sample, and followed the dissolved isotope composition of the mixture during the following two months. The initial dissolved Pb concentration was 18.3 pmol/kg with 206Pb/207Pb of 1.200. "Total dissolvable" Pb released after acidification of the in the unfiltered sample was 373 pmol/kg with 206Pb/207Pb of 1.199, indicating that there is a large particulate Pb reservoir with an isotopic composition comparable to regional crustal natural Pb. The isotope spike should have brought the dissolved 206Pb/207Pb to 1.162, but less than a day after isotope spiking, the dissolved Pb had risen to 1.181 and continued a slow increase to 1.197 over the next two months. This experiment demonstrates that Johor estuary particulate matter contains a large reservoir of exchangeable Pb that will modify the isotopic composition of deposited aeolian aerosol anthropogenic Pb. We have modeled the evolution of Pb and Pb isotopes in this experiment with a single Kd -type model that assumes that there are two or three different Pb reservoirs with different exchange time constants. This observation has implications for isotope equilibrium between high Pb/210Pb continental particles and low Pb/210Pb ocean waters - what is merely isotope equilibration may appear to be 210Pb scavenging.

  1. Ancient Pb and Ti mobilization revealed by Scanning Ion Imaging

    NASA Astrophysics Data System (ADS)

    Kusiak, Monika A.; Whitehouse, Martin J.; Wilde, Simon A.

    2014-05-01

    Zircons from strongly layered early Archean ortho- and paragneisses in ultra-high temperature (UHT) metamorphic rocks of the Napier Complex, Enderby Land, East Antarctica are characterized by complex U-Th-Pb systematics [1,2,3]. A large number of zircons from three samples, Gage Ridge, Mount Sones and Dallwitz Nunatak, are reversely discordant (U/Pb ages older than 207Pb/206Pb ages) with the oldest date of 3.9 Ga [4] (for the grain from Gage Ridge orthogneiss). To further investigate this process, we utilized a novel high spatial resolution Scanning Ion Imaging technique on the CAMECA IMS 1280 at the Natural History Museum in Stockholm. Areas of 70 μm x 70 μm were selected for imaging in mono- and multicollection modes using a ~2 μm rastered primary beam to map out the distribution of 48Ti, 89Y, 180Hf, 232Th, 238U, 204Pb, 206Pb and 207Pb. The ion maps reveal variable distribution of certain elements within analysed grains that can be compared to their CL response. Yttrium, together with U and Th, exhibits zonation visible on the CL images, Hf shows expected minimal variation. Unusual patchiness is visible in the map for Ti and Pb distribution. The bright patches with enhanced signal do not correspond to any zones or to crystal imperfections (e.g. cracks). The presence of patchy titanium is likely to affect Ti-in-zircon thermometry, and patchy Pb affecting 207Pb/206Pb ages, usually considered as more robust for Archean zircons. Using the WinImage program, we produced 207Pb/206Pb ratio maps that allow calculation of 207Pb/206Pb ages for spots of any size within the frame of the picture and at any time after data collection. This provides a new and unique method for obtaining age information from zircon. These maps show areas of enhanced brightness where the 207Pb/206Pb ratio is higher and demonstrate that within these small areas (μm scale) the apparent 207Pb/206Pb age is older, in some of these patches even > 4 Ga. These data are a result of ancient Pb

  2. Geochemical Characteristics of Volcanic Rocks from the Southern Okinawa Trough and its Implications for Tectono-magmatic Evolution

    NASA Astrophysics Data System (ADS)

    Shinjo, R.; Hokakubo, S.; Haraguchi, S.; Matsumoto, T.; Woodhead, J.

    2003-12-01

    The Okinawa Trough is a site of ongoing backarc rifting behind the Ryukyu arc-trench system. Recent intensive surveys, including submersible dives, at the southern Okinawa Trough (SOT) have revealed details of bathymetric, geological, and geophysical features. Here, we present the petrological and geochemical characteristics of volcanic rocks collected during these cruises, and discuss its relation to the evolutionary stage of rifting. Based on bathymetirc and magmatic features, SOT can be divided into two (i.e., eastern and western) segments with non-transform offset at ˜ 123.5° E. The eastern segment represents a well-developed rift system with E-W-trending central graben and separated NE-SW-trending volcanic front; these two features merge at ˜ 125° E. In contrast, the western segment is in the incipient rifting stage; rift axis exists close to 100 km contour of the Wadati-Benioff zone. The most notable feature is the presence of 'abnormal' volcanic chain (Cross Backarc Volcanic Trail, CBVT), which trends NE-SW and is obviously oblique to the axial trend. All rocks are subalkaline, but range from basalt to rhyolite; dacite-rhyolite are dominant in the eastern volcanic front and CBVT. Basalts from both segments are low-K tholeiites; they have high abundance of LILEs relative to HFSEs, negative Nb anomalies on MORB-normalized diagrams, and range of 143Nd/144Nd (0.5128-0.5129) and 87Sr/86Sr (0.7034-0.7048). Pb isotope systematics indicate 206Pb/204Pb=18.398-18.582, 207Pb/204Pb=15.594-15.652 and 208Pb/204Pb=38.570-38.912, clearly above the Northern Hemisphere Reference Line. These elemental and isotopic variations are compatible with derivation from Indian Ocean MORB-like mantle with strong overprint of subduction components from the slab. There is clear difference among more felsic rocks between two segments. At similar silica contents, most of felsic rocks from the western segment, including CBVT rhyolites, have higher LILE contents, 87Sr/86Sr and 208Pb/204Pb

  3. Early Cretaceous continental delamination in the Yangtze Block: Evidence from high-Mg adakitic intrusions along the Tanlu fault, central Eastern China

    NASA Astrophysics Data System (ADS)

    Jia, Liqiong; Mo, Xuanxue; Santosh, M.; Yang, Zhusen; Yang, Dan; Dong, Guochen; Wang, Liang; Wang, Xinchun; Wu, Xuan

    2016-09-01

    Early Cretaceous high-Mg adakitic rocks from central Eastern China provide important insights into the thinning mechanism of the over-thickened lithosphere in the Yangtze Block (YB) as well as the North China Block (NCB). The Tanlu fault (TLF), located between the North China and Yangtze Blocks, and has been considered as a prominent pathway of magmas and fluids that resulted in lithosphere thinning of the YB during the Mesozoic-Cenozoic. Here we report the petrology, whole-rock geochemistry, zircon U-Pb geochronology, in situ Hf isotopes, and whole-rock Sr-Nd-Pb isotopes of four high-Mg adakitic intrusions along the TLF in northeastern Langdai. These adakitic intrusions consist of monzodiorite, quartz monzonite porphyry, and quartz monzodiorite. Zircon LA-MC-ICPMS analyses of five samples yield weighted mean 206Pb/238U ages of 127.58 ± 0.80, 126.90 ± 0.81, 120.71 ± 0.64, 122.75 ± 0.57, and 129.2 ± 1.1 Ma, indicating their emplacement during the Early Cretaceous. The intrusions have intermediate SiO2 (53.18-65.48 wt%) and high potassium (K2O = 3.07-3.95 wt%; Na2O/K2O = 1.02-1.26) and are classified as shoshonitic to high-K calc-alkaline series. They are characterized by high MgO (1.80-7.35 wt%), Mg# (50-65), Sr (591-1183 ppm), Ni (20.3-143.0 ppm), and Cr (51.40-390.0 ppm) contents, high (La/Yb)N (11.60-28.33) and Sr/Y (27.9-113.5) ratios, and low Y (7.79-22.4 ppm) and Yb (0.60-2.01 ppm) contents, comparable with high-Mg adakites. The samples are enriched in light rare earth elements but depleted in heavy rare earth elements and high field strength elements with slightly negative to positive Eu anomalies (δEu = 0.81-1.30), resembling the features of high-Mg adakitic rocks. Their whole-rock εNd(t) = -16.2 to -15.0, initial (87Sr/86Sr)i = 0.7060-0.7074, low radiogenic Pb (206Pb/204Pb(t) = 16.208-16.509, 207Pb/204Pb(t) = 15.331-15.410, and 208Pb/204Pb(t) = 36.551-36.992), and zircon εHf(t) = -36.6 to -16.6 suggest magma derivation from a continental crustal

  4. Pb Isotopes as Tracers of Weathering in Glacial Systems

    NASA Astrophysics Data System (ADS)

    Martin, E. E.; Deuerling, K. M.; Scribner, C. A.; Martin, J. B.; Clements, K.

    2013-12-01

    Incongruent chemical weathering of freshly exposed continental material produces weathering solutions with Sr and Pb isotopic values that are distinctly more radiogenic than the parent material. As soils age, weathering becomes more congruent and the isotopic ratio in the solution approaches the composition of parent material. In light of this response, rapid increases in seawater Pb isotopes in the North Atlantic over the last deglacial have been attributed to incongruent weathering of fine grained glacial sediment exposed as the ice sheet retreated. This theory has not been tested using modern glacial river systems due to concerns about contamination by anthropogenic Pb. In this study we analyzed Pb isotopes from: 1) leachates of moraine material, 2) bedload and river water samples along a proglacial river, and 3) sediment and water samples from closed basin lakes in deglaciated terrains, from the Kangerlussuaq region of western Greenland. As expected, 0.1N HCl leachates of moraine soils exhibit 206,207,208Pb/204Pb ratios that are more radiogenic than the bulk soil. Samples from a Little Ice Age moraine close to the Russell Glacier exhibit greater offsets between the leachate and bulk soil Pb isotopes than samples from Orkendalen moraines (6.8 ka), which also record a slightly greater offset than Umivit-Keglen moraines (7.3 ka). Proglacial Watson (Akuliarusuarsuup Kuua) River water samples collected closest to the Russell Glacier also record the most radiogenic Pb isotopes and the largest increase relative to bedload values. Bedload 206Pb/204Pb ratios along the 40 km length of the proglacial river are 14.7+/0.6. Values for all water samples are distinctly more radiogenic than bedload, with the highest value (18.02) closest to the glacier and a general decreasing trend to ~15.82 farthest from the glacier. For comparison to anthropogenic Pb isotopes, 206Pb/207Pb ratios are 1.00+/-.03 for bedload, with water values ranging from 1.18 to 1.06 in a decreasing trend

  5. On the recent enrichment of subcontinental lithosphere: A detailed UPb study of spinel lherzolite xenoliths, Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Carignan, Jean; Ludden, John; Francis, Don

    1996-11-01

    Lead strontium, and osmium isotopic data have been obtained for whole rocks and mineral separates (olivine, orthopyroxene, clinopyroxene, and spinel) for spinel lherzolite xenoliths hosted by lavas of the Quaternary Alligator Lake volcanic centre, southern Yukon. Whole-rock xenolith samples display a large variation of lead concentrations, from 16 ppb for a harzburgite to up to 400 ppb for a lherzolite. However, their lead isotope ratios are relatively homogeneous with 206Pb /204Pb of 19.07 ± 0.08, 207Pb /204Pb of 15.65 ± 0.07, and 208Pb /204Pb of 38.67 ± 0.17 ( n = 7). However, the 238U /204Pb ratios display a large variation, from 12.2 to 46.5, and do not correlate with indices of fertility such as calcium or aluminum content. Mineral separates yield even larger variations in lead isotopic composition and lead and uranium concentrations. Some olivine fractions have both the lowest radiogenic compositions ( 206Pb /204Pb = 18.75 ) and the lowest 238U /204Pb ratios (˜3.1). Clinopyroxenes (cpx) display the highest lead and uranium concentrations (up to 1277 ppb and 195 ppb, respectivelly) and generally similar or more radiogenic lead isotopic composition and higher 238U /204Pb ratios than their whole-rock compositions. Orthopyroxene and spinel fractions yield intermediate compositions between olivine and cpx. Although whole rocks and cpx for individual samples yield almost identical 87Sr /86Sr , the xenoliths ( n = 5) display a large variation of strontium isotopic compositions ( 87Sr /86Sr from 0.07033 to 0.7050), lead and strontium isotope ratios of cpx and the distribution of the data in a UPb isochron diagram suggest that the subcontinental lithosphere under the Yukon was affected by a recent (< ˜30 Ma) enrichment in uranium, lead, and strontium. The metasomatic fluid/magma might have had an isotopic composition close to that of some sediments in the northern Pacific Ocean. When compared to K d values reported in the literature, olivine is enriched in

  6. Isotopes and trace elements as geo-location markers for biosecurity: determining the origin of exotic pests.

    NASA Astrophysics Data System (ADS)

    Holder, Peter W.; Armstrong, Karen; Clough, Tim; Frew, Russell; van Hale, Robert; Baker, Joel A.; Millet, Marc-Alban

    2010-05-01

    insects, the influence of polyphagy and local variation in precipitation 2H. This improved understanding is being applied to assess the validity of using heavy and light element isotope ratio and trace element profiles to differentiate insects of New Zealand natal origin from insects of exotic origin. Results. An integrated method of TC-IRMS, TI-MS, MC-ICP-MS and ICP-MS analyses of natural abundance 2H, 87Sr/86Sr, 207Pb/206Pb and 208Pb/206Pb isotope ratios and trace element profiles from single insect specimens has been developed. No single geo-location marker has been found in a preliminary comparison of international moths, although the latitudinal cline of δ2H on a continental scale is confirmed. However, multivariate analysis revealed that successful geo-location discrimination between the study regions is possible. Conclusion. The promising but imperfect geo-location demonstrated provides solid leads for further investigation. Any geo-location system developed is likely to be applicable to other disciplines, including forensics, ecological studies and pest management.

  7. Using stable isotope systematics and trace metals to constrain the dispersion of fish farm pollution

    NASA Astrophysics Data System (ADS)

    Torchinsky, A.; Shiel, A. E.; Price, M.; Weis, D. A.

    2010-12-01

    from the reference site. It is thought that resuspension of particulate waste could be responsible for concentrating waste far from the fish farm. No pattern was observed in the trace metal concentration measurements (Cu = 4.11 - 9.64 ppm, Zn 40.0 - 107 ppm and Pb 0.008 - 0.086 ppm) of the clams suggesting differences in the dispersion of metal contaminants and organic waste. Lead isotope ratios (1.14874 to 1.74100 for 206Pb /207Pb and 2.07579 to 2.10615 for 208Pb /206Pb) indicate the importance of anthropogenic Pb sources in the study area (i.e., unleaded gasoline and diesel fuel consumption and metal smelting), however, the anthropogenic Pb sources are unlikely to be associated with the open-net salmon farm. Waste dispersion from open-net fish farms is complicated by physical oceanographic conditions, which characterize individual study areas, this must be taken into account when interpreting results and designing future studies.

  8. The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition - Implications for the rifting of Ganderia

    USGS Publications Warehouse

    Schulz, K.J.; Stewart, D.B.; Tucker, R.D.; Pollock, J.C.; Ayuso, R.A.

    2008-01-01

    interlayered with basalt in the Ellsworth Schist, is calc-alkaline and characterized by relatively low REE, Zr, and Hf contents, enriched LREE ([La/Yb]N ???3-6), positive Th and negative Th anomalies, ??Nd (500) values near zero (+0.5 to -0.9), and relatively unradiogenic Ph isotope values (206Pb/204Pb = 18.845; 207Pb/ 204Pb = 15.625; 208Pb/204Pb = 38.626). The data suggest that R-1 rhyolite magma was Likely derived by mixing of basalt with melts from a relatively depleted crustal source. Type R-2 rhyolite, which mostly occurs as lava flows and domes in the Castine volcanics, is tholeiitic and characterized by enriched REE with flat patterns ([La/Yb]N = 1-2.5), moderate negative Eu anomalies (Eu/Eu* = 0-34.5), enriched Th, small negative Th anomalies, and ??Nd (500) (+5.8-+7.5) and Ph isotope (206Pb/204Pb = 19.175-19.619; 207Pb/204Pb = 15.605--15.649; 208Pb/204Pb = 38.834-38.851) values that overlap those of the tholeiitic basalts. The data suggest that R-2 rhyolite magma was derived by the partial melting of hydrothermally altered basalt with the addition of a small amount of an enriched component, probably R-1 rhyolite. The geololic, geochemicai, and isotopic characteristics of the bimodal volcanic sequences strongly suggest that the Ellsworth terrane did not evolve as an extensional back-arc basin behind an active arc, but rather it evolved as a proto-oceanic rift petrogenetically similar to Cenozoic rifts like the Gulf of California-Salton mrough and Red Sea-Gulf of Aden rift systems. Such a setting is supported by the presence of serpentinized mantle and zinc-copper-rich massive sulfide deposits in the Ellsworth terrane. We conclude that the Ellsworth terrane developed as a Mid

  9. Lead isotope and trace element composition of urban soils in Mongolia

    NASA Astrophysics Data System (ADS)

    Tserenpil, Sh.; Sapkota, A.; Liu, C.-Q.; Peng, J.-H.; Liu, B.; Segebade, P. Chr.

    2016-08-01

    Lead (Pb) pollution in and around Ulaanbaatar is of national concern, given that the Mongolian capital is home to nearly half of the country's entire population. By comparison, Mongolian countryside is a pristine environment because of its sparse population and low industrial activity. The concentration of Pb in urban soils (average of 39.1 mg kg-1) was twice the values found (average 18.6 mg kg-1) in background territories (i.e., Mongolian rural sites). Furthermore, Pb contamination was examined by using Pb stable isotopic composition, and covariance of Pb isotopic ratios showed two groups between rural and urban soils as pristine and disturbed sites. The 206Pb/207Pb ratio, the most prominent fingerprint for Pb pollution, was 1.163-1.185 for the urban whereas values for rural soils (1.186-1.207) were analogue to the regional Pb isotopic signatures. Local coal sources and their combustion products, one of the potential Pb pollution sources in Ulaanbaatar, have significant radiogenic properties in terms of Pb isotopic composition and revealed an average of 1.25 for 206Pb/207Pb and 19.551 for 206Pb/204Pb ratios. Thus, contributions from coal firing activity to Pb pollution lower than it was assumed, and smaller range of these values measured in urban soils may be attributed to the mixing of less radiogenic Pb as a constituent of the leaded gasolines.

  10. Final report of the key comparison CCQM-K98: Pb isotope amount ratios in bronze

    NASA Astrophysics Data System (ADS)

    Vogl, Jochen; Yim, Yong-Hyeon; Lee, Kyoung-Seok; Goenaga-Infante, Heidi; Malinowskiy, Dmitriy; Ren, Tongxiang; Wang, Jun; Vocke, Robert D., Jr.; Murphy, Karen; Nonose, Naoko; Rienitz, Olaf; Noordmann, Janine; Näykki, Teemu; Sara-Aho, Timo; Ari, Betül; Cankur, Oktay

    2014-01-01

    Isotope amount ratios are proving useful in an ever increasing array of applications that range from studies unravelling transport processes, to pinpointing the provenance of specific samples as well as trace element quantification by using isotope dilution mass spectrometry (IDMS). These expanding applications encompass fields as diverse as archaeology, food chemistry, forensic science, geochemistry, medicine and metrology. However, to be effective tools, the isotope ratio data must be reliable and traceable to enable the comparability of measurement results. The importance of traceability and comparability in isotope ratio analysis has already been recognized by the Inorganic Analysis Working Group (IAWG) within the CCQM. While the requirements for isotope ratio accuracy and precision in the case of IDMS are generally quite modest, 'absolute' Pb isotope ratio measurements for geochemical applications as well as forensic provenance studies require Pb isotope ratio measurements of the highest quality. To support present and future CMCs on isotope ratio determinations, a key comparison was urgently needed and therefore initiated at the IAWG meeting in Paris in April 2011. The analytical task within such a comparison was decided to be the measurement of Pb isotope amount ratios in water and bronze. Measuring Pb isotope amount ratios in an aqueous Pb solution tested the ability of analysts to correct for any instrumental effects on the measured ratios, while the measurement of Pb isotope amount ratios in a metal matrix sample provided a real world test of the whole chemical and instrumental procedure. A suitable bronze material with a Pb mass fraction between 10 and 100 mg•kg-1 and a high purity solution of Pb with a mass fraction of approximately 100 mg•kg-1 was available at the pilot laboratory (BAM), both offering a natural-like Pb isotopic composition. The mandatory measurands, the isotope amount ratios n(206Pb)/n(204Pb), n(207Pb)/n(204Pb) and n(208Pb)/n(204Pb

  11. Historical perspective of industrial lead emissions to the atmosphere from a Canadian smelter.

    PubMed

    Gallon, Céline; Tessier, André; Gobeil, Charles; Carignan, Richard

    2006-02-01

    Dated sediment cores from four remote Canadian Shield headwater lakes, where atmospheric deposition has been the only input of anthropogenic Pb, situated along a transect extending 300 km from a nonferrous metal smelter, were analyzed for both lead concentrations and isotopic composition; porewater samples collected at the same sites were analyzed for Pb and other geochemical variables. The depth distributions of stable Pb isotope ratios show the presence of several isotopically distinct Pb types since the preindustrial period. Lead from the smelter emissions had an isotopic signature (e.g., 206Pb/207Pb approximately 0.993) that was clearly distinct from those of Pb in aerosols collected at sites remotefrom point sources in Eastern Canada (e.g., 206Pb/207Pb usually approximately 1.15-1.20) and the United States (e.g., 206Pb/207Pb usually approximately 1.15-1.22), allowing the geographical area impacted by the smelter Pb emissions to be traced. On the basis of the sediment Pb isotopic composition, it is estimated that lead from the smelter accounts for 89%, 88%, and 5-34% of the total inventory of anthropogenic Pb deposited in the sediments of lakes located 10, 25, and 150 km from the smelter, respectively; but lead from this point source was not detected in sediments of a fourth lake that is 300 km from the smelter. We also estimate that the amount of smelter-derived Pb deposited within a distance of 150 km is equivalent to 5-10% of the amount released by leaded gasoline combustion in all of Canada. Sharp decreases in the recent Pb fluxes to lake sediments indicate that the measures taken to mitigate metal emissions from the smelter were effective.

  12. Isotopically constrained lead sources in fugitive dust from unsurfaced roads in the southeast Missouri mining district

    USGS Publications Warehouse

    Witt, Emitt C.; Pribil, Michael; Hogan, John P; Wronkiewicz, David

    2016-01-01

    The isotopic composition of lead (Pb) in fugitive dust suspended by a vehicle from 13 unsurfaced roads in Missouri was measured to identify the source of Pb within an established long-term mining area. A three end-member model using 207Pb/206Pb and concentration as tracers resulted in fugitive dust samples plotting in the mixing field of well characterized heterogeneous end members. End members selected for this investigation include the 207Pb/206Pb for 1) a Pb-mixture representing mine tailings, 2) aerosol Pb-impacted soils within close proximity to the Buick secondary recycling smelter, and 3) an average of soils, rock cores and drill cuttings representing the background conditions. Aqua regia total concentrations and 207Pb/206Pb of mining area dust suggest that 35.4–84.3% of the source Pb in dust is associated with the mine tailings mixture, 9.1–52.7% is associated with the smelter mixture, and 0–21.6% is associated with background materials. Isotope ratios varied minimally within the operational phases of sequential extraction suggesting that mixing of all three Pb mixtures occurs throughout. Labile forms of Pb were attributed to all three end members. The extractable carbonate phase had as much as 96.6% of the total concentration associated with mine tailings, 51.8% associated with smelter deposition, and 34.2% with background. The next most labile geochemical phase (Fe + Mn Oxides) showed similar results with as much as 85.3% associated with mine tailings, 56.8% associated with smelter deposition, and 4.2% associated with the background soil.

  13. Pb isotope variations in olivine-hosted melt inclusions from South Tyrrhenian volcanoes

    NASA Astrophysics Data System (ADS)

    Rose-Koga, E. F.; Koga, K. T.; Schiano, P.; Shimizu, N.; Whitehouse, M.; Clocchiatti, R.

    2009-12-01

    Melt inclusions in primitive olivine crystals isolate the instantaneous composition of primitive magmas. Recent studies have reported a very large range of isotope ratios among olivine-hosted melt inclusions from some single volcanoes even though the erupted lavas from these volcanoes are isotopically homogeneous. This implies that magmas with different isotopic compositions exist in the volcanic plumbing system before melt aggregation, reflecting a range of source compositions. Volcanoes in the South Italy region (Stromboli, Vulcano islands, Mount Etna including Aci Castello, the oldest Etnean volcanics, as well as present-day Etnean basalts, Marsili seamount and Ustica Island) shows a wide spectrum of magma-types where predominantly calc-alkaline magmatism is found in the Aeolian Islands and a magmatism of Na-alkaline nature dominates the nearby Eastern Sicily volcanoes (Mount Etna) and Ustica Island. The complex geodynamic evolution of this region is the probable cause of this diverse magma composition produced from the Pliocene to recent times. We analyzed 12 olivine-hosted melt inclusions from those six volcanoes for Pb isotopes by a multicollection SIMS 1280 (NMNH Stockholm, Sweden) and volatiles by a monocollection SIMS 1280 (WHOI, USA). The repeated 207Pb/206Pb measurements of the GOR132 glass standard (20 ppm Pb) yielded a 0.15% relative variation (1 sigma of the distribution). For the modern Etna (2002 lava), the 207Pb/206Pb isotope variations of the melt inclusions overlap and extend that of the whole rocks (from 0.788±0.002 to 0.820±0.002 (MI) relative to 0.7863 to 0.8037 (WR)). The melt inclusions from Aci Costello display more clustered and intermediate 207Pb/206Pb values between 0.801±0.003 and 0.811±0.005. The Pb isotope variations of the melt inclusions from the other volcanoes displays value similar to that of their whole rock data, up to 207Pb/206Pb of 0.828 for Marsili melt inclusions. There are no obvious correlations between Pb isotopes

  14. In situ ion microprobe U-Pb dating and REE abundances of a carboniferous conodont

    NASA Astrophysics Data System (ADS)

    Sano, Yuji; Terada, Kentaro

    We report here in situ ion microprobe U-Pb dating of a conodont micro-fossil using an ion microprobe method. Thirteen spots on the single fragment of the Carboniferous conodont (size: approximately 800 µm × 100 µm) yield a 238U/206Pb isochron age of 323±36 Ma and a Tera-Wasserburg concordia intercept age of 332±44 Ma in a three-dimensional 238U/206Pb-207Pb/206 Pb-204Pb/206Pb diagram. These ages are consistent with the depositional and early diagenetic ages of the fossil in its host Mississippian sedimentary sequence within experimental error. The success of the method depends on the chemical fractionation of U from Pb within a hundred-µm length scale and the consequent variations in Pb isotopic compositions due to radioactive decay. Shale-normalized rare earth element (REE) abundances of two spots on the same sample show flat patterns from light REE to middle REE and decreases from middle REE to heavy REE with negative anomalies of both Ce and Eu. The REE characteristics are significantly different from those of Devonian conodonts reported by other workers, suggesting discrepant redox states and/or formation environments.

  15. Investigation of the Photoneutron Cross Section in LEAD-206 and LEAD-208 from 9 TO 16 Mev

    NASA Astrophysics Data System (ADS)

    Morford, Larry Joe

    The time of flight of photoneutrons from ('206)Pb and ('208)Pb was observed at scattering angles of 55(DEGREES), 90(DEGREES), and 125(DEGREES). Photons with energies between 9 and 16 MeV were used to excite the target nuclei. The incident photon beam was provided by the University of Illinois Tagged Photon Facility and had an effective energy resolution of around 400 keV. Neutron energies were determined by time of flight through a 1.5 meter path. The effective energy resolution of the neutrons was between 7.6% at 1 MeV and 12.5% at 5 MeV. Neutron detector efficiency was determined by measuring the photo-disintegration of deuterium. The resulting efficiency was found to be constant across the neutron energy range of interest. The fraction of neutrons with energy insufficient to pass the detector threshold was estimated to be 10.7%. The total cross section for both ('206)Pb and ('208)Pb are well described by Lorentzian curves with widths of 4.12 (+OR-) 0.24 MeV for ('206)Pb and 4.09 (+OR-) 0.38 MeV for ('208)Pb. The peak positions of the curves were determined to be 13.70 (+OR-) 0.06 MeV for ('206)Pb and 13.53 (+OR-) 0.05 MeV in ('208)Pb. No angular asymmetry about 90(DEGREES) in the differential cross sections was detected in either element above 11 MeV. Below 11 MeV the asymmetry varied with energy between alternate positive and negative values for each element. The time-of-flight spectra could be parameterized for low energy neutrons by a statistical decay with a nuclear temperature of 0.9 MeV. There was an excess of high energy neutrons above this distribution. A more detailed analysis of the spectra using the Hauser-Feshbach formalism suggests that this excess is also from the statistical decay of the nucleus.

  16. Basalt Petrogenesis Beneath Slow - and Ultraslow-Spreading Arctic Mid-Ocean Ridges

    DTIC Science & Technology

    2009-02-01

    0.70274-0.70301), εHf (16.59-19.56), and Pb isotopes (e.g. 208Pb/206Pb = 2.043-2.095). This suggests a homogeneous mantle source and a long peridotite ...number of upper mantle rocks can contain Gt, the stability of Gt in peridotite depends on pressure. Thus if the host of Gt is peridotite , the dominant... peridotite , I have measured U and Th partition coefficients in silica-poor garnet pyroxenite, a minor mantle lithology for which such measurements

  17. A Primer on the Detection of Nuclear and Radiological Weapons

    DTIC Science & Technology

    2005-05-01

    signals or samples molecules from nuclear materials and turns them into information. This is indicated schematically in figure 12. The front end ...short-lived isotopes ending in stable 208Pb. The most prominent gamma rays are 239 keV from 212Pb, 511, 583 and 2614 keV from 208Tl, and 911 and...isotopes ending in 206Pb. The most prominent gamma rays are 609, 1120, and 1764 keV from 214Bi. • Potassium activity is due to decay of 40K, which

  18. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: Is this really archean crust?

    USGS Publications Warehouse

    Premo, Wayne R.; Castineiras, Pedro; Wooden, Joseph L.

    2008-01-01

    New SHRIMP-RG (sensitive high-resolution ion microprobe-reverse geometry) data confirm the existence of Archean components within zircon grains of a sample from the orthogneiss of Angel Lake, Nevada, United States, previously interpreted as a nappe of Archean crust. However, the combined evidence strongly suggests that this orthogneiss is a highly deformed, Late Cretaceous monzogranite derived from melting of a sedimentary source dominated by Archean detritus. Zircon grains from the same sample used previously for isotope dilution-thermal ionization mass spectrometry (ID-TIMS) isotopic work were analyzed using the SHRIMP-RG to better define the age and origin of the orthogneiss. Prior to analysis, imaging revealed a morphological variability and intragrain, polyphase nature of the zircon population. The SHRIMP-RG yielded 207Pb/206Pb ages between ca. 2430 and 2580 Ma (a best-fit mean 207Pb/206Pb age of 2531 ± 19 Ma; 95% confidence) from mostly rounded to subrounded zircons and zircon components (cores). In addition, several analyses from rounded to subrounded cores or grains yielded discordant 207Pb/206Pb ages between ca. 1460 and ca. 2170 Ma, consistent with known regional magmatic events. All cores of Proterozoic to latest Archean age were encased within clear, typically low Th/U (206Pb/238U ages between 72 and 91 Ma, consistent with magmatic ages from Lamoille Canyon to the south. An age of ca. 90 Ma is suggested, the younger 206Pb/238U ages resulting from Pb loss. The Cretaceous and Precambrian zircon components also have distinct trace element characteristics, indicating that these age groups are not related to the same igneous source. These results support recent geophysical interpretations and negate the contention that the Archean-Proterozoic boundary extends into the central Great Basin area. They further suggest that the world-class gold deposits along the Carlin Trend are not underlain by Archean cratonal crust, but rather b