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71.
Haosheng Wu Roman Bttger Frdric Couffignal Jens Gutzmer Joachim Krause Frans Munnik Axel D. Renno Ren Hübner Michael Wiedenbeck Ren Ziegenrücker 《Geostandards and Geoanalytical Research》2019,43(4):531-541
Although electron probe microanalysis and secondary ion mass spectrometry are widely used analytical techniques for geochemical and mineralogical applications, metrologically rigorous quantification remains a major challenge for these methods. Secondary ion mass spectrometry (SIMS) in particular is a matrix‐sensitive method, and the use of matrix‐matched reference materials (RMs) is essential to avoid significant analytical bias. A major problem is that the number of available RMs for SIMS is extremely small compared with the needs of analysts. One approach for the production of matrix‐specific RMs is the use of high‐energy ion implantation that introduces a known amount of a selected isotope into a material. We chose the more elaborate way of implanting a so‐called ‘box‐profile’ to generate a quasi‐homogeneous concentration of the implanted isotope in three dimensions, which allows RMs not only to be used for ion beam analysis but also makes them suitable for EPMA. For proof of concept, we used the thoroughly studied mineralogically and chemically ‘simple’ SiO2 system. We implanted either 47Ti or 48Ti into synthetic, ultra‐high‐purity silica glass. Several ‘box‐profiles’ with mass fractions between 10 and 1000 μg g?1 Ti and maximum depths of homogeneous Ti distribution between 200 nm and 3 μm were produced at the Institute of Ion Beam Physics and Materials Research of Helmholtz‐Zentrum Dresden‐Rossendorf. Multiple implantation steps using varying ion energies and ion doses were simulated with Stopping and Range of Ions in Matter (SRIM) software, optimising for the target concentrations, implantation depths and technical limits of the implanter. We characterised several implant test samples having different concentrations and maximum implantation depths by means of SIMS and other analytical techniques. The results show that the implant samples are suitable for use as reference materials for SIMS measurements. The multi‐energy ion implantation technique also appears to be a promising procedure for the production of EPMA‐suitable reference materials. 相似文献
72.
This article contributes to a small but growing body of multi-sited and multi-scalar research on the Belt and Road Initiative.We focus on relations at the national,regional and international scales,and present original research from China and Turkey,to show how the Istanbul-Ankara high-speed railway has served as a testing ground for China's Belt and Road Initiative(BRI).Its construction was initially funded by the European Investment Bank,but it is now part of the backbone of the Turkish Government's Middle Corridor plan which enhances west-east connectivity and integration with the Caucasus and Central Asia.We show that in contrast to multinational corporations from the OECD that seek to remain footloose,Chinese state-owned enterprises(SOEs)seek to adapt to,apprehend and ultimately shape local in-stitutions.In the case of Turkey this proved difficult given its institutional alignment with the European Union.Thus,while the railway project was completed successfully by a consortium led by a Chinese SOE,Turkey's dynamic and complex regulatory environment discourages Chinese SOEs in the infrastructure sector.We conclude that the Turkish and Chinese gov-ernments are currently pursuing complementary territorial visions yet their cooperation is project-based and pragmatic. 相似文献
73.
Appropriate conditions have been achieved for the accurate, rapid, and highly precise shipboard simultaneous determination of dissolved organic carbon and total dissolved nitrogen in seawater by high temperature catalytic oxidation. A nitrogen-specific Antek 705D chemiluminescence detector and a CO2-specific LiCor Li6252 IRGA have been coupled in-series with a Shimadzu TOC-5000 organic carbon analyser. Precision of both simultaneous measurements is ≤1.5%, i.e. ±1 μmol C l−1 and ±0.3 μmol N l−1, respectively. Quality of analysis is not compromised by vibrations associated with ocean going research vessels. 相似文献
74.
75.
Storm runoff from the Marikina River Basin frequently causes flood events in the Philippine capital region Metro Manila. This paper presents and evaluates a system to predict short-term runoff from the upper part of that basin (380 km2). It was designed as a possible component of an operational warning system yet to be installed. For the purpose of forecast verification, hindcasts of streamflow were generated for a period of 15 months with a time-continuous, conceptual hydrological model. The latter was fed with real-time observations of rainfall. Both ground observations and weather radar data were tested as rainfall forcings. The radar-based precipitation estimates clearly outperformed the raingauge-based estimates in the hydrological verification. Nevertheless, the quality of the deterministic short-term runoff forecasts was found to be limited. For the radar-based predictions, the reduction of variance for lead times of 1, 2 and 3 hours was 0.61, 0.62 and 0.54, respectively, with reference to a “no-forecast” scenario, i.e. persistence. The probability of detection for major increases in streamflow was typically less than 0.5. Given the significance of flood events in the Marikina Basin, more effort needs to be put into the reduction of forecast errors and the quantification of remaining uncertainties. 相似文献
76.
Shenyang Yu Qijian Li Stephen Kershaw Axel Munnecke Yingyan Mao Yue Li 《Island Arc》2024,33(1):e12512
The Xiangshuyuan Formation (middle Rhuddanian to middle Aeronian stages of the Llandovery Series, lower Silurian) records a shelly fauna representing recovery after the end-Ordovician mass extinction in a well-oxygenated shallow carbonate platform of the Upper Yangtze region, South China Block. Carbon isotope stratigraphy is documented from limestone sequences of the formation at the Qiankou section, northeast Guizhou. The early Aeronian carbon isotope excursion (EACIE, with an amplitude of about 2 ‰ and peak value of 2.44 ‰) is identified in the middle and upper parts of the formation (Ozarkodina obesa conodont Biozone). The EACIE recorded herein correlates well with those in Baltica, Canada, and the United States; together with its records from organic material (δ13Corg) the data verify that the EACIE is a global event. The beginning of the EACIE can be used as a chemostratigraphic marker defining the Rhuddanian/Aeronian boundary in strata that lack high-resolution biostratigraphic constraints. 相似文献
77.
A New Appraisal of Sri Lankan BB Zircon as a Reference Material for LA‐ICP‐MS U‐Pb Geochronology and Lu‐Hf Isotope Tracing
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Maristella M. Santos Cristiano Lana Ricardo Scholz Ian Buick Mark D. Schmitz Sandra L. Kamo Axel Gerdes Fernando Corfu Simon Tapster Penelope Lancaster Craig D. Storey Miguel A.S. Basei Eric Tohver Ana Alkmim Herminio Nalini Klaus Krambrock Cristiano Fantini Michael Wiedenbeck 《Geostandards and Geoanalytical Research》2017,41(3):335-358
A potential zircon reference material (BB zircon) for laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) U‐Pb geochronology and Hf isotope geochemistry is described. A batch of twenty zircon megacrysts (0.5–1.5 cm3) from Sri Lanka was studied. Within‐grain rare earth element (REE) compositions are largely homogeneous, albeit with some variation seen between fractured and homogeneous domains. Excluding fractured cathodoluminescence bright domains, the variation in U content for all analysed crystals ranged from 227 to 368 μg g?1 and the average Th/U ratios were between 0.20 and 0.47. The Hf isotope composition (0.56–0.84 g/100 g Hf) is homogeneous within and between the grains – mean 176Hf/177Hf of 0.281674 ± 0.000018 (2s). The calculated alpha dose of 0.59 × 1018 g?1 for a number of BB grains falls within the trend of previously studied, untreated zircon samples from Sri Lanka. Aliquots of the same crystal (analysed by ID‐TIMS in four different laboratories) gave consistent U‐Pb ages with excellent measurement reproducibility (0.1–0.4% RSD). Interlaboratory assessment (by LA‐ICP‐MS) from individual crystals returned results that are within uncertainty equivalent to the TIMS ages. Finally, we report on within‐ and between‐grain homogeneity of the oxygen isotope systematic of four BB crystals (13.16‰ VSMOW). 相似文献
78.
Oscar?LaurentEmail author Armin?Zeh Axel?Gerdes Arnaud?Villaros Katarzyna?Gros Ewa?S?aby 《Contributions to Mineralogy and Petrology》2017,172(9):80
In plutonic systems, magma mixing is often modelled by mass balance based on whole-rock geochemistry. However, magma mixing is a chaotic process and chemical equilibration is controlled by non-linear diffusive–advective processes unresolved by the study of bulk samples. Here we present textural observations, LA-(MC-)ICP-MS trace element and Sr–Nd isotopic data of accessory apatites and titanites from a hybrid granodiorite of the Neoarchean Matok pluton (South Africa), collected in a zone of conspicuous mixing between mafic and felsic magmas. Apatite grains mostly show a pronounced zoning in CL images, corresponding to abrupt changes in REE and HFSE concentrations recording their transfer through compositionally different melt domains during mixing. These grains crystallized early, at temperatures of 950–1000 °C. Titanite grains crystallized at temperatures of 820–900 °C (Zr-in-sphene thermometry). They show limited intra-grain chemical variations but huge inter-grain compositional scatter in REE and HFSE, pinpointing crystallization within a crystal mush, from isolated melt pockets having different composition from one another owing to incomplete chemical homogenization and variable Rayleigh fractionation. These chemical–textural characteristics, in combination with partitioning models and Polytopic Vector Analysis, point to “self-mixing” between co-genetic dioritic and granodioritic/granitic magmas. Both resulted from differentiation of mantle-derived mafic melts, showing that mixing does not necessarily involve magmas from contrasted (crust vs. mantle) sources. Systematic variations in εNd t (?4.5 to ?2.5) and 87Sr/86Sr(i) (0.703–0.707) of titanite and apatite grains/domains crystallized from the two magmas point to an isotopically inhomogeneous mantle source, which is not resolved by bulk-rock isotopic data. Interaction between the two magmas must have occurred at relatively high temperatures (ca. 900°C) so that their viscosity contrast remained low, allowing efficient mechanical mixing. Despite this, chemical homogenization was incomplete, as recorded by diffusive fractionation between REE–HFSE and Sr. Modelling thereof reveals that chemical exchange between the liquid phases of the two mixed magmas did not last more than a few tens to hundreds of years. The chemical equilibration between mixed magmas thus strongly depends on the considered elements and observational length scales. 相似文献
79.
80.
西藏甲玛铜多金属矿区成矿斑岩的岩浆混合作用:石英及长石斑晶新证据 总被引:6,自引:3,他引:3
西藏甲玛矿区斑岩内石英和长石斑晶的阴极发光(CL)特征及元素含量变化有效记录了岩浆演化、混合及补给事件.石英斑晶的显微生长结构表明,原始岩浆经历过2次铁镁质岩浆混合作用.根据石英斑晶中Ti含量的变化可知,在2次溶蚀前后,石英结晶温度分别增高了约110℃和80℃.此外,斜长石斑晶的反环带及其Ba、Sr、Fe等元素的浓度梯... 相似文献