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Auteur : Grafiati
Publié le 10 mars 2023

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1

Yobregat, Elsa, Caroline Fitoussi et Bernard Bourdon. « A new method for TIMS high precision analysis of Ba and Sr isotopes for cosmochemical studies ». Journal of Analytical Atomic Spectrometry 32, no 7 (2017) : 1388–99. http://dx.doi.org/10.1039/c7ja00012j.

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2

Thorrold, Simon R., et Stephen Shuttleworth. « In situ analysis of trace elements and isotope ratios in fish otoliths using laser ablation sector field inductively coupled plasma mass spectrometry ». Canadian Journal of Fisheries and Aquatic Sciences 57, no 6 (1 juin 2000) : 1232–42. http://dx.doi.org/10.1139/f00-054.

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We applied laser ablation sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) to the analysis of trace element and isotopic signatures in fish otoliths. Manganese, Sr, and Ba profiles across juvenile Atlantic croaker (Micropogonias undulatus) otoliths, expressed as ratios to Ca, showed considerable spatial and temporal variations that were presumably reflective of variations in water chemistry over the same scales. Differences in otolith Mn:Ca ratios between adjacent rivers in Pamlico Sound, North Carolina, may be related to dissolved oxygen levels in the rivers through reductive release of Mn2+ from sediments. Strontium and Ba profiles appeared to accurately reflect differences in dissolved Sr and Ba in freshwater end-members, both between Pamlico Sound and Chesapeake Bay and between seasons within Chesapeake Bay. High-precision analyses of Sr:Ca ratios in a black drum (Pogonias cromis) otolith showed distinctive quasi-sinusoidal cycles that were correlated with validated annual bands. Analyses of Sr and Pb isotopes, in otoliths and standard reference material, respectively, found that SF-ICP-MS produced accurate and precise estimates of isotope ratios in both solution-based and laser ablation assays.
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Barnett-Johnson, Rachel, Frank C. Ramos, Churchill B. Grimes et R. Bruce MacFarlane. « Validation of Sr isotopes in otoliths by laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) : opening avenues in fisheries science applications ». Canadian Journal of Fisheries and Aquatic Sciences 62, no 11 (1 novembre 2005) : 2425–30. http://dx.doi.org/10.1139/f05-194.

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Advances in probe-based mass spectrometry allow for high spatial resolution of elemental and isotopic signatures in fish otoliths that can be used to address fundamental questions in fisheries ecology. Analyses of Chinook salmon (Oncorhynchus tshawytscha) otoliths from two river populations yield identical 87Sr/86Sr ratios using laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) and thermal ionization mass spectrometry (TIMS). Results were obtained from freshwater otoliths with low Sr concentrations (300–800 ppm) using high spatial resolution (50 µm) corresponding to temporal histories of ~12 days fish growth. Low natural variation in 87Sr/86Sr among otoliths from the same rivers allows for conservative estimates of external precision of techniques. Thus, we demonstrate that Sr isotope ratios obtained by LA-MC-ICPMS can be accurate and precise, bypassing the time-intensive sample preparation required by microdrilling and TIMS. This technique opens the use of Sr isotopes for broader ecological questions requiring large sample sizes to characterize nursery habitats, metapopulation dynamics, and stock discrimination similar to studies that focus on elemental concentrations, thereby providing a more robust tool for some freshwater and diadromous fishes.
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Nan, Xiaoyun, Huimin Yu, Jinting Kang et Fang Huang. « Re-visiting barium isotope compositions of mid-ocean ridge basalts and the implications ». JUSTC 52, no 3 (2022) : 1. http://dx.doi.org/10.52396/justc-2021-0276.

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Barium (Ba) isotopes can be used as potential tracers for crustal material recycling in the mantle. Determination of the Ba isotope composition of the depleted mantle is essential for such applications. However, Ba isotope data for mantle-derived basalts are still rare. In this study, we reported high-precision Ba isotope data of 30 oceanic basalts including 25 mid-ocean ridge basalts (MORBs) from geochemically and geologically diverse mid-ocean ridge segments and five back-arc basin basalts. The δ<sup>138/134</sup>Ba values of these samples varied from −0.06‰ to +0.11‰, with no systematic cross-region variation. Together with published data, we constrained the average δ<sup>138/134</sup>Ba of global MORBs to +0.05‰±0.09‰ (2 standard deviation, <i>n</i> = 51). Based on depleted MORBs that have (La/Sm)<sub>N</sub> < 0.8, low <sup>87</sup>Sr/<sup>86</sup>Sr (< 0.70263), and low Ba/Th < 71.3, we estimated the average δ<sup>138/134</sup>Ba of the depleted MORB mantle (DMM) as + 0.05‰ ± 0.05‰ (2SD, <i>n</i> = 16) that is significantly lower than the DMM (≈ 0.14‰) reported previously. If a new estimation of the DMM is applied, it is unreasonable to infer that the Ba isotope signatures of the “enriched-type” MORBs (E-MORBs) could be attributed to pervasive sediment recycling in the upper mantle. We, therefore, conclude that the Ba isotope compositions of the E-MORBs could be sourced from the incorporation of subducted altered oceanic crust and/or sediments depending on the Ba isotope composition and other geochemical information of the local mantle.
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Armstrong, Richard Lee, Randall R. Parrish, Peter van der Heyden, Krista Scott, Dita Runkle et Richard L. Brown. « Early Proterozoic basement exposures in the southern Canadian Cordillera : core gneiss of Frenchman Cap, Unit I of the Grand Forks Gneiss, and the Vaseaux Formation ». Canadian Journal of Earth Sciences 28, no 8 (1 août 1991) : 1169–201. http://dx.doi.org/10.1139/e91-107.

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The protolith age of high-grade metamorphic rocks exposed in structurally deep parts of the Omineca Crystalline Belt has been the subject of investigation and controversy for decades. We have applied multiple isotopic dating techniques to rocks of three structural culminations: the Monashee complex (which includes the Frenchman Cap and Thor–Odin gneiss domes), the Grand Forks horst, and the Vaseaux Formation, which lies in the footwall of the Okanagan Valley fault.Frenchman Cap core gneisses contain highly radiogenic Sr that scatters about a 2206 ± 117 Ma (1σ) Rb–Sr isochron with 87Sr/86Sr initial ratio of 0.700 ± 0.002. Monazite and zircon dates for the same rocks are 1851 ± 7 to 2103 ± 16 Ma (only U–Pb dates are given with 2σ errors), with lower intercepts from about 100 to 300 Ma. Sm–Nd whole-rock and crustal-residence (TDM) dates are 2.3 ± 0.2 Ga. Mafic–felsic layering in the core gneiss is also of Early Proterozoic age. There is no geochronometric evidence for Late Proterozoic or Mesozoic migmatization.Frenchman Cap mantling gneisses, including samples from above the Monashee décollement, have radiogenic Sr and unradiogenic Nd compositions that are not consistent with current inferences of a Late Proterozoic to Paleozoic depositional age. Two intrusive granitic rocks, which cut mantling gneiss, are either Early Proterozoic or Mesozoic–Cenozoic with a Proterozoic Sr isotopic signature acquired by assimilation of core gneiss. One other intrusive studied is probably Paleocene Ladybird granite. The age of the mantling gneiss is not yet consistently resolved.Grand Forks Gneiss Unit I paragneiss gives radiogenic whole-rock Sr, zircon U–Pb upper intercept, and Sm–Nd whole-rock crustal-residence dates of 1.7 ± 0.4 Ga, 1681 ± 3 Ma (2σ, but the apparent high precision is very dependent on the assumption made about the time of Pb loss), and 1.9 ± 0.3 Ga, respectively. Unit II and younger Grand Forks Gneiss units are Late Proterozoic or Phanerozoic. All isotope systems have been considerably reset on a centimetre to metre scale by Mesozoic–Cenozoic regional metamorphism. Grand Forks Sr, Pb, and Nd isotope data are much like those for Spokane area pre-Purcell basement.Vaseaux Formation micaceous schist and gneiss give radiogenic whole-rock Sr, zircon U–Pb upper intercept, and Sm–Nd crustal-residence dates of 2.1 ± 0.6 Ga, 1899 ± 49 Ma (2σ), and 2.2 ± 0.1 Ga, respectively. Hornblende-bearing schist and gneiss contain much less radiogenic Sr and more radiogenic Nd. The latter are either tectonic intercalations of Late Proterozoic to Paleozoic eugeosynclinal rocks or Mesozoic–Cenozoic mixtures of mantle-derived magma and older crustal rock. The Vaseaux Formation paragneiss is similar isotopically to paragneiss in the Frenchman Cap core gneiss. This may indicate a similar age, or that Vaseaux sedimentary rocks could be much younger and isochemically derived from a basement of Frenchman Cap character. The first alternative is favored because the three isotope systems are usually not preserved in unison through sedimentary processes. Sr isotopes, in particular, do not usually preserve a provenance age.In all three areas, late Mesozoic to early Cenozoic metamorphic monazite, hornblende, muscovite, and biotite dates provide a record of cooling from a Cretaceous to Paleocene culmination of regional metamorphism, with particularly rapid cooling during Paleocene to Eocene crustal extension and tectonic unroofing.The localities studied are tectonic windows on structural culminations that expose basement that we infer to be part of North America. Their ages fit the pattern of basement ages established for the stable craton. Their extent is consistent with the reconstruction of compressed miogeoclinal rocks. The eastern half of the Cordilleran region on both sides of the United States – Canada border is underlain by Early Proterozoic basement that was attenuated in Late Proterozoic time, compressed during Mesozoic–Cenozoic orogeny, and finally extended in early Cenozoic collapse of the thickened crust. During Mesozoic–Cenozoic orogeny the sedimentary cover of that basement was pushed approximately 200 km eastward and replaced by allochthonous terranes. The tectonic displacements documented in the southern Canadian Cordillera are truly exceptional.
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Ku, Teh-Lung, M. Ivanovich et Shangde Luo. « U-Series Dating of Last Interglacial High Sea Stands : Barbados Revisited ». Quaternary Research 33, no 2 (mars 1990) : 129–47. http://dx.doi.org/10.1016/0033-5894(90)90014-c.

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AbstractU-series chronologies of the emerged coral limestone terraces on Barbados, West Indies, together with those of the terraces from New Guinea, have formed the basis for most late Pleistocene eustatic models. The so-called “Barbados sea level model” has been challenged in recent years, however. A major issue is whether during oxygen isotope stage 5e, when Rendezvous Hill reef complex on Barbados Island formed, the sea rose above the present position for one relatively brief period of <10,000 yr, or for two or more periods spanning approximately from 140,000 to 115,000 yr B.P. Evidence for the latter scenario has not come from initial studies of Barbados but from elsewhere; it is also inconclusive because of the dating uncertainties involved. We have carried out careful redeterminations of U-series ages on a suite of 29 Acropora palmata samples systematically collected from four of the lowest terraces on the island. Diagenetic disturbance may have caused the age spreads at some sampling outcrops. A model for the diagenetic exchange of uranium isotopes in coral samples with those in groundwater explains the anomalous 234U/238U ratios in samples with apparently unaltered mineralogy (aragonite) and trace element (Mg and Sr) chemistry. It shows that age dispersions of 5–10% can be engendered by a U exchange coefficient of the order of 10−6 yr−1. The lower-limit terrace ages, estimated from averaging the multiple measurements, are 81,000 ± 2000 yr (Worthing), 105,000 ± 1000 yr (Ventnor), 120,000 ± 2000 yr (Maxwell), and 117,000 ± 3000 yr (Rendezvous Hill). No evidence was found of previously inferred bipartite sea levels centering around 118,000 and 135,000 yr ago. This study documents the need of dating coral with the high precision/sensitivity mass-spectrometric techniques for future resolution of the temporal relationships among sea level changes, climate oscillations, and astronomical forcing—relationships originally addressed by the Barbados sea level model.
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7

Di Salvo, Sara, Eleonora Braschi, Martina Casalini, Sara Marchionni, Teresa Adani, Maurizio Ulivi, Andrea Orlando et al. « High-Precision In Situ 87Sr/86Sr Analyses through Microsampling on Solid Samples : Applications to Earth and Life Sciences ». Journal of Analytical Methods in Chemistry 2018 (2018) : 1–20. http://dx.doi.org/10.1155/2018/1292954.

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An analytical protocol for high-precision, in situ microscale isotopic investigations is presented here, which combines the use of a high-performing mechanical microsampling device and high-precision TIMS measurements on micro-Sr samples, allowing for excellent results both in accuracy and precision. The present paper is a detailed methodological description of the whole analytical procedure from sampling to elemental purification and Sr-isotope measurements. The method offers the potential to attain isotope data at the microscale on a wide range of solid materials with the use of minimally invasive sampling. In addition, we present three significant case studies for geological and life sciences, as examples of the various applications of microscale 87Sr/86Sr isotope ratios, concerning (i) the pre-eruptive mechanisms triggering recent eruptions at Nisyros volcano (Greece), (ii) the dynamics involved with the initial magma ascent during Eyjafjallajökull volcano’s (Iceland) 2010 eruption, which are usually related to the precursory signals of the eruption, and (iii) the environmental context of a MIS 3 cave bear, Ursus spelaeus. The studied cases show the robustness of the methods, which can be also be applied in other areas, such as cultural heritage, archaeology, petrology, and forensic sciences.
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Lin, Jie, Yongsheng Liu, Haihong Chen, Lian Zhou, Zhaochu Hu et Shan Gao. « Review of High-Precision Sr Isotope Analyses of Low-Sr Geological Samples ». Journal of Earth Science 26, no 5 (octobre 2015) : 763–74. http://dx.doi.org/10.1007/s12583-015-0593-0.

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Nguyen Thi Kim, Dung, et Thuy Thai Thi Thu. « Study on the removal of interferences for the determination of ⁸⁷Sr/⁸⁶Sr isotopic ratio in petroleum drill-hole water samples using isotope dilution – inductively coupled plasma mass spectrometry (ID – ICP-MS) ». Nuclear Science and Technology 8, no 4 (1 septembre 2021) : 34–43. http://dx.doi.org/10.53747/jnst.v8i4.65.

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87Sr/86Sr isotopic ratio is one of the useful tools that can authenticate the original source of the natural products from the earth-created and/or geological processes. However, the effect of interferences in petroleum drill-holes water sample such as thickness of sample matrix or isotopic signal of 87Rb might cause the low precision of 87Sr/86Sr determination using quadrupole inductively coupled plasma spectrometry (ICP-MS). The elimination of these mentioned effects was thus studied by using the ion - exchange chromatography. Calcium in sample matrix was separated on anionite column (Bio-Rad AG1-X8 resin) in methanol medium with the high efficiency while rubidium wasremoved from strontium on cation exchange resin (Bio-Rad AG50-X8) with strontium recovery over 99%. The isotope dilution technique with 86Sr - enriched isotopic standard solution was used for the control of separation process. The 87Sr/86Sr isotopic ratio was thus determined using ICP-MS with the signal correction by a strontium isotopic ratio standard reference material (NIST SRM 987).
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Zhang, Zhuoying, Jinlong Ma, Le Zhang, Ying Liu et Gangjian Wei. « Rubidium purificationviaa single chemical column and its isotope measurement on geological standard materials by MC-ICP-MS ». Journal of Analytical Atomic Spectrometry 33, no 2 (2018) : 322–28. http://dx.doi.org/10.1039/c7ja00406k.

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A chromatographic procedure for Rb, K, Ba and Sr one-by-one separation from geological materials has been developed by using a single column with packing Sr-spec resin, followed by high-precision Rb isotope measurement by MC-ICP-MS.
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11

Nebel, O., et K. Mezger. « Reassessment of the NBS SRM-607 K-feldspar as a high precision Rb/Sr and Sr isotope reference ». Chemical Geology 233, no 3-4 (octobre 2006) : 337–45. http://dx.doi.org/10.1016/j.chemgeo.2006.03.003.

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12

Sigmarsson, Olgeir, et Sæmundur Ari Halldórsson. « Delimiting Bárðarbunga and Askja volcanic systems with Sr- and Nd-isotope ratios ». Jökull 65, no 1 (15 décembre 2015) : 17–27. http://dx.doi.org/10.33799/jokull2015.65.017.

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Volcanic systems represent a fundamental component of the neovolcanic zones in Iceland. They are composed of a central volcano and a fissure swarm, or a combination of the two. The 2014–2015 rifting event at the Bárðarbunga volcanic system produced basaltic lava approximately 40 km to the north of the central volcano, within a fissure swarm commonly attributed to the Askja volcanic system, highlighting the complex tectonic structure of a region, directly above the Iceland mantle plume. New analyses of Sr- and Nd-isotope ratios from the new lava (Holuhraun), and the underlying older Holuhraun lava, show that they have identical values to those of the Bárðarbunga-Veiðivötn lavas and tephra erupted during the Holocene. Moreover, comparison with published high-precision radiogenic isotope data, reveals that Holocene lavas and tephra from the Bárðarbunga and Askja systems are characterized by contrasting Sr- and Nd-isotope ratios, with the notable exception of the Þjórsárhraun lava and two early Holocene lavas from the extreme west and east of the Veiðivötn fissure swarm. The $^{87}$Sr/$^{86}$Sr and $^{143}$Nd/$^{144}$Nd isotope ratios can thus be utilized to define the provenance of lava flows north of the Vatnajökull ice cap, ascertaining that the large lava fields of Krepputunguhraun and Fjallsendahraun (Frambruni) must also have originated within the Bárðarbunga volcanic system.
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Jweda, Jason, Louise Bolge, Cornelia Class et Steven L. Goldstein. « High Precision Sr-Nd-Hf-Pb Isotopic Compositions of USGS Reference Material BCR-2 ». Geostandards and Geoanalytical Research 40, no 1 (19 mars 2015) : 101–15. http://dx.doi.org/10.1111/j.1751-908x.2015.00342.x.

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Li, Chao-Feng, Jing-Hui Guo, Yue-Heng Yang, Zhu-Yin Chu et Xuan-Ce Wang. « Single-step separation scheme and high-precision isotopic ratios analysis of Sr–Nd–Hf in silicate materials ». J. Anal. At. Spectrom. 29, no 8 (2014) : 1467–76. http://dx.doi.org/10.1039/c3ja50384d.

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Genske, Felix, Andreas Stracke, Jasper Berndt et Stephan Klemme. « Process-related isotope variability in oceanic basalts revealed by high-precision Sr isotope ratios in olivine-hosted melt inclusions ». Chemical Geology 524 (octobre 2019) : 1–10. http://dx.doi.org/10.1016/j.chemgeo.2019.04.031.

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Kaufman, Darrell, L. David Carter, Gifford H. Miller, G. Lang Farmer et David A. Budd. « Strontium isotopic composition of Pliocene and Pleistocene molluscs from emerged marine deposits, North American Arctic ». Canadian Journal of Earth Sciences 30, no 3 (1 mars 1993) : 519–34. http://dx.doi.org/10.1139/e93-041.

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High-precision strontium (Sr) isotopic measurements were obtained for 53 Pliocene and Pleistocene molluscan shells from emerged marine deposits around the coasts of Arctic North America to test whether such data can be used for chronostratigraphic purposes. 87Sr/86Sr ratios from Sr isotopic measurements on many marine fossils from Arctic Ocean borderland sites are broadly consistent with their expected values based on independent age control and on a comparison with the Sr isotopic evolution of seawater recorded in deep-sea cores. All 87Sr/86Sr ratios measured for shells from Middle and Late Pleistocene deposits are consistent with expected values, but only 9 of 22 ratios in shells from older deposits are consistent with independent age estimates. Aberrant 87Sr/86Sr ratios are consistently higher than expected. At Nome, Alaska, and Baffin Island, Canada, all 87Sr/86Sr ratios are higher than expected. Because these shells were formed along the Pacific Ocean and Atlantic Ocean margins, respectively, their high 87Sr/86Sr ratios cannot be attributed to possible differences in the Sr isotopic evolution of the Arctic Ocean relative to that of remainder of the world's oceans. Radiogenic Sr from proximal river-water input, or leaching of detritus within the shell matrix, may have changed the 87Sr/86Sr ratios by as much as about 5 × 10−5, but these mechanisms cannot account for the very high 87Sr/86Sr values (from 20 × 10−5 to 200 × 10−5 higher than those of modern seawater) measured for some shells. Alteration by diagenetic fluids rich in radiogenic Sr is the most plausible explanation for the aberrant results. Diagenesis is recognized petrographically in the most altered shells by micritic overprinting of the original shell microstructure; in addition, one shell enriched in 87Sr from Baffin Island exhibits a broad range (170 × 10−5) of 87Sr/86Sr ratios across the shell, and an oxygen isotopic gradient (l.6‰) that is greater than the expected primary variability. Although our data suggest that Sr isotopic data from young Arctic molluscan fossils may offer a viable dating method, criteria for screening altered shells must be devised before the technique can be considered a reliable chronostratigraphic tool.
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Liu, Wen-Gang, Shuang Wei, Jian Zhang, Cong Ao, Fu-Tian Liu, Bin Cai, Hong-Ying Zhou, Ji-Long Yang et Chao-Feng Li. « An improved separation scheme for Sr through fluoride coprecipitation combined with a cation-exchange resin from geological samples with high Rb/Sr ratios for high-precision determination of Sr isotope ratios ». Journal of Analytical Atomic Spectrometry 35, no 5 (2020) : 953–60. http://dx.doi.org/10.1039/d0ja00035c.

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Di, Yankun, Evgenii Krestianinov, Sonja Zink et Yuri Amelin. « High-precision multidynamic Sr isotope analysis using thermal ionization mass spectrometer (TIMS) with correction of fractionation drift ». Chemical Geology 582 (novembre 2021) : 120411. http://dx.doi.org/10.1016/j.chemgeo.2021.120411.

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Schuth, S., C. Münker, S. König, S. Basi, C. Qopoto et C. Ballhaus. « High precision Pb and Sr–Nd–Hf isotope constraints on mantle source variations along the Solomon arc ». Geochimica et Cosmochimica Acta 70, no 18 (août 2006) : A566. http://dx.doi.org/10.1016/j.gca.2006.06.1048.

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Zhou, Ting, Liang Qi, Haifeng Fan et Runsheng Yin. « An optimized protocol for high precision measurement of 87Sr/86Sr using a Neptune Plus multi-collector inductively coupled plasma mass spectrometer : evaluation of different cone combinations for Sr isotope determination ». Analytical Methods 12, no 32 (2020) : 4089–96. http://dx.doi.org/10.1039/d0ay00845a.

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Li, Xiaoqiang, et Guilin Han. « One-step chromatographic purification of K, Ca, and Sr from geological samples for high precision stable and radiogenic isotope analysis by MC-ICP-MS ». Journal of Analytical Atomic Spectrometry 36, no 3 (2021) : 676–84. http://dx.doi.org/10.1039/d0ja00467g.

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This study presents a method for one-step chromatographic separation of K–Ca–Sr from matrix elements, and the purification procedure is based on AG50W-X12 cation exchange resin without any intervening evaporation step.
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Jamin, Eric, Frédérique Martin, Gilles G. Martin, I. Billault, A. I. Blanch-Cortès, C. Fauhl, C. Guillou et al. « Determination of Site-Specific (Deuterium/Hydrogen) Ratios in Vanillin by 2H-NuclearMagnetic Resonance Spectrometry : Collaborative Study ». Journal of AOAC INTERNATIONAL 90, no 1 (1 janvier 2007) : 187–95. http://dx.doi.org/10.1093/jaoac/90.1.187.

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Abstract The results of collaborative study are reported for a method that determines the site-specific isotope ratios of deuterium/hydrogen (D/H)i in vanillin by deuterium-nuclear magnetic resonance (2H-NMR) spectrometry. This method allows characterization of all the main commercial sources of commercial vanillin and detection of undeclared mixtures. It is based on the fact that the amounts of deuterium at various positions in the vanillin molecule are significantly different from one source to another. Vanillin is dissolved in acetonitrile and analyzed with a high-field NMR spectrometer fitted with a deuterium probe and a fluorine lock. The proportions of isotopomers monodeuterated at each hydrogen position of the molecule are recorded, and the corresponding (D/H) ratios are determined by using a calibrated reference. Nine laboratories analyzed 5 materials supplied as blind duplicates (1 natural vanillin from vanilla beans, 2 synthetic vanillins from guaiacol, 1 semisynthetic vanillin from lignin, and a mixture of natural and synthetic vanillins). The precision of the method for measuring site-specific ratios was as follows: for (D/H)1 the within-laboratory standard deviation (sr) values ranged from 2.2 to 5.8 ppm, and the among-laboratories standard deviation (sR) values ranged from 3.6 to 5.1 ppm; for (D/H)3 the sr values ranged from 1.7 to 3.2 ppm, and the sR values ranged from 2.4 to 3.7 ppm; for (D/H)4 the sr values ranged from 2.3 to 6.2 ppm, and the sR values ranged from 2.4 to 6.4 ppm; for (D/H)5 the sr values ranged from 0.8 to 2.7 ppm, and the sR values ranged from 0.9 to 2.3 ppm. It was shown that these values allow a satisfactory discrimination between vanillin sources. Therefore, the Study Director recommends the method for adoption as a First Action Official Method by AOAC INTERNATIONAL.
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ANDO, ATSUSHI, TAKANORI NAKANO, HODAKA KAWAHATA, YUSUKE YOKOYAMA et BOO-KEUN KHIM. « Testing seawater Sr isotopic variability on a glacial-interglacial timescale : An application of latest high-precision thermal ionization mass spectrometry ». GEOCHEMICAL JOURNAL 44, no 5 (2010) : 347–57. http://dx.doi.org/10.2343/geochemj.1.0074.

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Li, Chao-Feng, Zhu-Yin Chu, Jing-Hui Guo, You-Lian Li, Yue-Heng Yang et Xiang-Hui Li. « A rapid single column separation scheme for high-precision Sr–Nd–Pb isotopic analysis in geological samples using thermal ionization mass spectrometry ». Analytical Methods 7, no 11 (2015) : 4793–802. http://dx.doi.org/10.1039/c4ay02896a.

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Barrett, T. J., et H. Friedrichsen. « Oxygen-isotopic composition of basalts from young spreading axes in the eastern Pacific ». Canadian Journal of Earth Sciences 24, no 11 (1 novembre 1987) : 2105–17. http://dx.doi.org/10.1139/e87-201.

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Oxygen-isotopic composition data are reported for young oceanic basalts from two different tectonic settings in the eastern Pacific: (1) the uppermost basement on the Galapagos Rift (< 1 Ma old), and (2) subbasement depths up to ≈150 m in the Gulf of California (≤ 3.5 Ma old). In the Galapagos area, whole-rock δ18O values exhibit a narrow range of 5.7–6.6‰, consistent with minimal to slight low-temperature alteration. Limited alteration probably reflects a combination of young basement age, low temperatures for solutions in the uppermost basement, and confinement of solutions mainly to discrete fractures. In the Gulf of California, by contrast, high whole-rock values are found at site 474A, near the Baja margin, where the greatest range in δ18O also occurs, from 2.5 to 12.5‰. This indicates considerable variation in both the temperature and degree of alteration at this site, probably a consequence of the heterogeneous basement sequence (intercalated pillow lavas, sills, and wet sediments). Differences in δ18O of up to 6‰ can exist over several metres, implying sharp changes in temperature or local water/rock ratio. The development of low-temperature alteration is more pronounced at site 474A (≈3.5 Ma) than at the several other (younger) crustal locations drilled in the Gulf of California, presumably because of longer exposure to seawater during recession of site 474A from the spreading axis.Analysis of primary magmatic phases at all sites yield 18O fractionations between plagioclase, clinopyroxene, and magnetite consistent with crystallization in a closed system and without high-temperature subsolidus reaction with seawater oxygen (even where sediments are intercalated within the basement). At site 485 in the Gulf of California, a thick basaltic sill yielded the lowest calculated crystallization temperatures (920 ± 50 °C) on the basis of plagioclase–magnetite fractionations; this agrees reasonably with groundmass quartz estimated to have formed at 860 ± 40 °C. Two vein carbonates from the uppermost part of the igneous sequence at this site were formed at temperatures of less than a few tens of degrees.We also report high-precision strontium- and oxygen-isotopic data on mineral separates from four basalts recovered at site 504B (6 Ma old). The most striking feature of these data is very substantial contamination of most mineral phases by seawater Sr, even though the same splits have typical primary magmatic oxygen-isotopic values. Relative to an unaltered mid-ocean ridge basalt 87Sr/86Sr value of 0.70265 ± 0.0001, 87Sr/86Sr ratios of plagioclase range from 0.70270 to 0.70359 (for apparently primary δ18O values of 5.35–5.75‰); for clinopyroxene, 87Sr/86Sr ratios range from 0.70309 to a very enriched value of 0.70695 (δ18O values of 4.97–5.30‰, with one value of 6.05‰). These results indicate that young basalts may have experienced significant interaction with seawater, which is not recorded in terms of oxygen-isotope exchange.
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Yang, Yue-Heng, Fu-Yuan Wu, Lie-Wen Xie, Jin-Hui Yang et Yan-Bin Zhang. « High-precision direct determination of the 87Sr/86Sr isotope ratio of bottled Sr-rich natural mineral drinking water using multiple collector inductively coupled plasma mass spectrometry ». Spectrochimica Acta Part B : Atomic Spectroscopy 66, no 8 (août 2011) : 656–60. http://dx.doi.org/10.1016/j.sab.2011.07.004.

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Tappe, Sebastian, Agnete Steenfelt et Troels Nielsen. « Asthenospheric source of Neoproterozoic and Mesozoic kimberlites from the North Atlantic craton, West Greenland : New high-precision U–Pb and Sr–Nd isotope data on perovskite ». Chemical Geology 320-321 (août 2012) : 113–27. http://dx.doi.org/10.1016/j.chemgeo.2012.05.026.

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Tai, Baoqiang, Wentian Mi, Genhou Wang, Yingjie Li et Xu Kong. « Petrogenesis and Tectonic Setting of Early Cretaceous Intrusive Rocks in the Northern Ulanhot Area, Central and Southern Great Xing’an Range, NE China ». Minerals 11, no 12 (14 décembre 2021) : 1414. http://dx.doi.org/10.3390/min11121414.

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Abundant Early Cretaceous magmatism is conserved in the central and southern Great Xing’an Range (GXR) and has significant geodynamic implications for the study of the Late Mesozoic tectonic framework of northeast China. In this study, we provide new high-precision U–Pb zircon geochronology, whole-rock geochemistry, and zircon Hf isotopic data for representative intrusive rocks from the northern part of the Ulanhot area to illustrate the petrogenesis types and magma source of these rocks and evaluate the tectonic setting of the central-southern GXR. Laser ablation inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U–Pb dating showed that magmatism in the Ulanhot area (monzonite porphyry: 128.07 ± 0.62 Ma, quartz monzonite porphyry: 127.47 ± 0.36, quartz porphyry: 124.85 ± 0.34, and granite porphyry: 124.15 ± 0.31 Ma) occurred during the Early Cretaceous. Geochemically, monzonite porphyry belongs to the metaluminous and alkaline series rocks and is characterized by high Al2O3 (average 17.74 wt.%) and TiO2 (average 0.88 wt.%) and low Ni (average 4.63 ppm), Cr (average 6.69 ppm), Mg# (average 31.11), Y (average 15.16 ppm), and Yb (average 1.62 ppm) content with enrichment in Ba, K, Pb, Sr, Zr, and Hf and depletion in Ti, Nb, and Ta. The granitic rocks (e.g., quartz monzonite porphyry, quartz porphyry, and granite porphyry) pertain to the category of high-K calc-alkaline rocks and are characterized by high SiO2 content (>66 wt.%) and low MgO (average 0.69 wt.%), Mg# (average 31.49 ppm), Ni (average 2.78 ppm), and Cr (average 8.10 ppm) content, showing an affinity to I-type granite accompanied by Nb, Ta, P, and Ti depletion and negative Eu anomalies (δEu = 0.57–0.96; average 0.82). The Hf isotopic data suggest that these rocks were the product of the partial melting of juvenile crustal rocks. Notably, fractionation crystallization plays a crucial role in the process of magma emplacement. Combining our study with published ones, we proposed that the Early Cretaceous intrusive rocks in the Ulanhot area were formed in an extensional tectonic background and compactly related to the subduction of the Paleo-Pacific Ocean plate.
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Yang, Yue‐Heng, Ming Yang, Klaus Peter Jochum, Shi‐Tou Wu, Han Zhao, Lie‐Wen Xie, Chao Huang, Xiu‐Chun Zhan, Jin‐Hui Yang et Fu‐Yuan Wu. « High‐Precision Sr‐Nd‐Hf‐Pb Isotopic Composition of Chinese Geological Standard Glass Reference Materials CGSG‐1, CGSG‐2, CGSG‐4 and CGSG‐5 by MC‐ICP‐MS and TIMS ». Geostandards and Geoanalytical Research 44, no 3 (22 mai 2020) : 567–79. http://dx.doi.org/10.1111/ggr.12322.

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Peytcheva, Irena, Elena Tacheva, Albrecht von Quadt et Rossen Nedialkov. « U-Pb zircon and titanite ages and Sr-Nd-Hf isotope constraints on the timing and evolution of the Petrohan-Mezdreya pluton (Western Balkan Mts, Bulgaria) ». Geologica Balcanica 47, no 2 (novembre 2018) : 25–46. http://dx.doi.org/10.52321/geolbalc.47.2.25.

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A combination of methods is applied in the present study to define the exact age of the Petrohan and Mezdreya plutons and trace their magma evolution. Field, petrological, and geochemical studies of the Petrohan pluton revealed its complex evolution and emphasized the role of magma mingling and mixing, complementary to the normal assimilation and fractional crystallization (AFC) processes. Using high-precision conventional U-Pb (CA)-ID-TIMS zircon and titanite dating in combination with CA-LA-ICP-MS zircon dating and tracing, we suggest an incremental growth of a common Petrohan-Mezdreya pluton. It was assembled over minimum 4.5 Ma from 311.14±0.48 Ma to 307.54±0.54 Ma. The younger age of the gabbro (308.12±0.33 Ma), compared with the age of granodiorites (311.14±0.48 Ma), provides numerical proofs for magma replenishment during the assembling of the Petrohan pluton. Whole-rock strontium-neodymium (initial 87Sr/86Sr ratios of 0.70521–0.70527 to 0.70462 and 143Nd/144Nd of 0.51221 to 0.51210) and Hf-zircon isotope data (ε-Hf from –5.8 to +3.6) argue for interaction of mantle derived magma with crustal melts but also mixing and mingling and transfer of zircon grains between the gabbroic and granitic melts. Possible petrogenetic scenario includes melting of subcontinental mantle lithosphere and crust and evolution trough AFC, FC and mingling/mixing processes. Considering the Petrohan-Mezdreya pluton as part of the Variscan orogeny in SE Europe, our new data support the accretion/collision of both the Balkan and Sredna Gora/Getic units with Moesia in the Early Carboniferous followed by syn- and post-collisional Carboniferous and Permian magmatism.
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Jofré, E., J. M. Almenara, R. Petrucci, R. F. Díaz, Y. Gómez Maqueo Chew, E. Martioli, I. Ramírez et al. « Gemini-GRACES high-quality spectra of Kepler evolved stars with transiting planets ». Astronomy & ; Astrophysics 634 (31 janvier 2020) : A29. http://dx.doi.org/10.1051/0004-6361/201936446.

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Aims. Kepler-278 and Kepler-391 are two of the three evolved stars known to date on the red giant branch (RGB) to host multiple short-period transiting planets. Moreover, the planets orbiting Kepler-278 and Kepler-391 are among the smallest discovered around RGB stars. Here we present a detailed stellar and planetary characterization of these remarkable systems. Methods. Based on high-quality spectra from Gemini-GRACES for Kepler-278 and Kepler-391, we obtained refined stellar parameters and precise chemical abundances for 25 elements. Nine of these elements and the carbon isotopic ratios, 12C∕13C, had not previously been measured. Also, combining our new stellar parameters with a photodynamical analysis of the Kepler light curves, we determined accurate planetary properties of both systems. Results. Our revised stellar parameters agree reasonably well with most of the previous results, although we find that Kepler-278 is ~15% less massive than previously reported. The abundances of C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, and Ce, in both stars, are consistent with those of nearby evolved thin disk stars. Kepler-391 presents a relatively high abundance of lithium (A(Li)NLTE = 1.29 ± 0.09 dex), which is likely a remnant from the main-sequence phase. The precise spectroscopic parameters of Kepler-278 and Kepler-391, along with their high 12C∕13C ratios, show that both stars are just starting their ascent on the RGB. The planets Kepler-278b, Kepler-278c, and Kepler-391c are warm sub-Neptunes, whilst Kepler-391b is a hot sub-Neptune that falls in the hot super-Earth desert and, therefore, it might be undergoing photoevaporation of its outer envelope. The high-precision obtained in the transit times allowed us not only to confirm Kepler-278c’s TTV signal, but also to find evidence of a previously undetected TTV signal for the inner planet Kepler-278b. From the presence of gravitational interaction between these bodies we constrain, for the first time, the mass of Kepler-278b (Mp = 56 −13+37 M⊕) and Kepler-278c (Mp = 35 −21+9.9 M⊕). The mass limits, coupled with our precise determinations of the planetary radii, suggest that their bulk compositions are consistent with a significant amount of water content and the presence of H2 gaseous envelopes. Finally, our photodynamical analysis also shows that the orbits of both planets around Kepler-278 are highly eccentric (e ~ 0.7) and, surprisingly, coplanar. Further observations (e.g., precise radial velocities) of this system are needed to confirm the eccentricity values presented here.
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Ganguly, Sourav, et Ramananda Chakrabarti. « High precision TIMS measurements of stable Sr isotopes (δ88/86Sr) of standards with different matrices and depth bound seawater samples from the Bay of Bengal using a new 87Sr-84Sr double-spike ». Journal of Analytical Atomic Spectrometry, 2022. http://dx.doi.org/10.1039/d2ja00187j.

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We report high precision stable Sr isotopic data (δ88/86Sr) using an 87Sr-84Sr double spike TIMS technique for a variety of standards with different matrices (carbonate, silicate, seawater, and pure Sr)....
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Wang, Jiuyuan, Andrew D. Jacobson, Bradley B. Sageman et Matthew T. Hurtgen. « Stable Ca and Sr isotopes support volcanically triggered biocalcification crisis during Oceanic Anoxic Event 1a ». Geology, 16 décembre 2020. http://dx.doi.org/10.1130/g47945.1.

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Large igneous province (LIP) eruptions are hypothesized to trigger biocalcification crises. The Aptian nannoconid crisis, which correlates with emplacement of the Ontong Java Plateau and Oceanic Anoxic Event 1a (OAE 1a, ca. 120 Ma), represents one such example. The Ca isotope (δ44/40Ca) system offers potential to detect biocalcification fluctuations in the rock record because Ca isotope fractionation is sensitive to precipitation rate. However, other primary and secondary processes, such as input-output flux perturbations and early diagenesis, can produce similar signals. Here, we exploit emergent properties of the stable Sr isotope (δ88/86Sr) system to resolve the origin of δ44/40Ca variability during OAE 1a. This study reports high-precision thermal ionization mass spectrometry (TIMS) δ44/40Ca, δ88/86Sr, and 87Sr/86Sr records for Hole 866A of Ocean Drilling Program Leg 143 drilled in Resolution Guyot, mid-Pacific Ocean. The samples span ~27 m.y. from the Barremian (ca. 127 Ma) to the Albian (ca. 100 Ma). The δ44/40Ca and δ88/86Sr secular trends differ from the 87Sr/86Sr record but mimic each other. δ44/40Ca and [Sr], as well as δ44/40Ca and δ88/86Sr, strongly correlate and yield slopes predicted for kinetic control, which demonstrates that variable mass-dependent fractionation rather than end-member mixing dominated the isotopic relationship between carbonates and seawater. Positive δ44/40Ca and δ88/86Sr shifts that begin before OAE 1a and peak within the interval are consistent with reduced precipitation rates. All results combined point to a cascade of effects on rate-dependent Ca and Sr isotope fractionation, which derive from the dynamic interplay between LIP eruptions and biocalcification feedbacks.
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Yoshimura, Toshihiro, Shigeyuki Wakaki, Nozomu Iwasaki, Tsuyoshi Ishikawa et Naohiko Ohkouchi. « Stable Sr isotope (88Sr/86Sr) fractionation in calcite precious corals ». Frontiers in Marine Science 9 (1 décembre 2022). http://dx.doi.org/10.3389/fmars.2022.1045909.

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Stable isotope ratios of Sr (88Sr/86Sr) are a novel indicator for identifying terrestrial and oceanic Sr cycling and biological processes. Here we evaluate the temperature dependence of stable Sr isotope ratios (δ88Sr) in the calcite skeletons of precious corals, known as octocorals. High-precision Sr isotope measurements by double spike thermal ionization mass spectrometry were applied to different precious corals (Corallium japonicum, Pleurocorallium elatius, P. konojoi, Corallium sp., Keratoisis sp., and Coralliidae sp.) collected from water depths of 30–1500 m in the Pacific Ocean, corresponding to annual mean water temperatures of 2.5 to 19.5°C. The precious corals showed mean δ88Sr values of 0.101 ± 0.023‰. The magnitude of Sr isotope fractionation between the skeleton and ambient seawater (Δ88Sr) is −0.291 and is about −0.1‰ lower than the value predicted from the precipitation of inorganic calcite. This fractionation is not affected by changes in skeletal Sr/Ca ratio and associated biological effects on δ88Sr are negligible. δ88Sr of precious coral skeleton is an excellent recorder of ambient seawater.
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Kalsbeek, Feiko. « Age determination of Precambrian rocks from Greenland : past and present ». GEUS Bulletin, 1 juin 1997, 55–59. http://dx.doi.org/10.34194/ggub.v176.5062.

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NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kalsbeek, F. (1997). Age determination of Precambrian rocks from Greenland: past and present. Geology of Greenland Survey Bulletin, 176, 55-59. https://doi.org/10.34194/ggub.v176.5062 _______________ Age determination is an essential part of many geological investigations. The ages of Phanerozoic sedimentary rocks are typically determined by palaeontological studies (often with high precision), but for Precambrian rocks as well as for younger igneous intrusions, precise ages can only be obtained by isotopic analysis of minerals or rocks. Isotopic (radiometric) age determination of Greenland rocks began in the early 1960s and has continued since with gradually improving methods. In this contribution, the development of geochronological knowledge of the Precambrian of Greenland is described in historical perspective, and an outline of new results is given. The history of geochronology can be roughly divided into three periods: 1) a period of single-sample K-Ar and Rb-Sr mineral or whole-rock age determinations; 2) a time when most ages were determined with the help of Rb-Sr and Pb-Pb whole-rock isochrons and multi-grain zircon U-Pb isotope data; 3) the present, where ‘single’ zircon U-Pb data are the preferred method to obtain rock ages. These stages in the development of radiometric dating methods partly overlap in time, and each has yielded very significant contributions to the knowledge of Precambrian evolution in Greenland.
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Luu, Tu-Han, Pamela Gutiérrez, Edward C. Inglis, Daniel Roberts et Catherine Chauvel. « High-precision Sr and Nd isotope measurements using a dynamic zoom lens-equipped thermal ionisation mass spectrometer ». Chemical Geology, août 2022, 121078. http://dx.doi.org/10.1016/j.chemgeo.2022.121078.

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Weis, Dominique, Bruno Kieffer, Claude Maerschalk, Wilma Pretorius et Jane Barling. « High-precision Pb-Sr-Nd-Hf isotopic characterization of USGS BHVO-1 and BHVO-2 reference materials ». Geochemistry, Geophysics, Geosystems 6, no 2 (février 2005). http://dx.doi.org/10.1029/2004gc000852.

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Wang, Jiuyuan, Yankun Di, Dan Asael, Noah J. Planavsky et Lidya G. Tarhan. « An investigation of factors affecting high-precision Sr isotope analyses (87Sr/86Sr and δ88/86Sr) by MC-ICP-MS ». Chemical Geology, février 2023, 121365. http://dx.doi.org/10.1016/j.chemgeo.2023.121365.

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Bröcker, Michael, Erik E. Scherer, Paris Xypolias et Melina Höhn. « The timing of blueschist-facies metamorphism in the Makrotantalon Unit on Andros Island, Greece : Cretaceous and Eocene high-pressure/low-temperature events ? » Geological Magazine, 16 mai 2022, 1–17. http://dx.doi.org/10.1017/s0016756822000280.

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Abstract This study corroborates interpretations suggesting that the Makrotantalon Unit on Andros represents a tectonic slice with Pelagonian affinity in the nappe stack of the Cycladic Blueschist Unit. Previously reported Cretaceous 40Ar–39Ar dates of a garnet-glaucophane schist from the Makrotantalon Unit could not be reproduced by Rb–Sr geochronology, but this is not an indication of contamination with excess Ar. Instead, the newly dated samples record disturbance of the Rb–Sr isotope system by partial recrystallization. Subsets of these phengite populations, representing the smaller grain-size fractions, yielded low-precision dates ranging from c. 21 to c. 15 Ma that document deformation-related resetting and recrystallization of a presumably Cretaceous white mica population. Although these Miocene dates cannot be linked with blueschist-facies metamorphism, they provide time constraints on the formation of shear zones that overprinted the original thrust contact during exhumation. The geological relevance of a Cretaceous high-pressure event is confirmed by a Rb–Sr date of c. 121 Ma for an epidote-glaucophane schist collected further away from the tectonic contact. The occurrence of a second blueschist-facies event in the Eocene is verified by Rb–Sr dates of two epidote-glaucophane schists (c. 40 Ma and c. 44 Ma) that can unambiguously be assigned to the Makrotantalon Unit.
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