Effects of melt percolation on highly siderophile elements and Os isotopes in subcontinental lithospheric mantle: A study of the upper mantle profile beneath Central Europe   总被引：1，自引：0，他引：1  

Lukáš Ackerman  Richard J. Walker  Lynnette Pitcher  Ladislav Strnad 《Geochimica et cosmochimica acta》2009,73(8):2400-5596

The effects of melt percolation on highly siderophile element (HSE) concentrations and Re-Os isotopic systematics of subcontinental lithospheric mantle are examined for a suite of spinel peridotite xenoliths from the 4 Ma Kozákov volcano, Bohemian Massif, Czech Republic. The xenoliths have previously been estimated to originate from depths ranging from ∼32 to 70 km and represent a layered upper mantle profile. Prior petrographic and lithophile trace element data for the xenoliths indicate that they were variably modified via metasomatism resulting from the percolation of basaltic melt derived from the asthenosphere. Chemical and isotopic data suggest that lower sections of the upper mantle profile interacted with melt characterized by a primitive, S-undersaturated composition at high melt/rock ratios. The middle and upper layers of the profile were modified by more evolved melt at moderate to low melt/rock ratios. This profile permits an unusual opportunity to examine the effects of variable melt percolation on HSE abundances and Os isotopes.Most HSE concentrations in the studied rocks are significantly depleted compared to estimates for the primitive upper mantle. The depletions, which are most pronounced for Os, Ir and Ru in the lower sections of the mantle profile, are coupled with strong HSE fractionations (e.g., Os_N/Ir_N ratios ranging from 0.3 to 2.4). Platinum appears to have been removed from some rocks, and enriched in others. This enrichment is coupled with lithophile element evidence for the degree of percolating melt fractionation (i.e., Ce/Tb ratio).Osmium isotopic compositions vary considerably from subchondritic to approximately chondritic (γ_Os at 5 Ma from -6.9 to +2.1). The absence of correlations between ¹⁸⁷Os/¹⁸⁸Os and indicators of fertility, as is common in many lithospheric mantle suites, may suggest significant perturbation of the Os isotopic compositions of some of these rocks, but more likely reflect the normal range of isotopic compositions found in the modern convecting mantle. Osmium isotopic compositions correspondingly yield model Re-depletion (T_RD) ages that range from essentially modern to ∼1.3 Ga.Our data provide evidence for large-scale incompatible behavior of HSE during melt percolation as a result of sulfide dissolution, consistent with observations of prior studies. The degree of incompatibility evidently depended on melt/rock ratios and the degree of S-saturation of the percolating melt. The high Pt contents of some of these rocks suggest that the Pt present in this pervasively metasomatized mantle was controlled by a phase unique to the other HSE. Further, high Os concentrations in several samples suggest deposition of Os in a minority of the samples by melt percolation. In these rocks, the mobilized Os was characterized by similar to the ¹⁸⁷Os/¹⁸⁸Os ratios in the ambient rocks. There is no evidence for either the addition of Os with a strongly depleted isotopic composition, or Os with suprachondritic isotopic composition, as is commonly observed under such circumstances.  相似文献   

Determination of Trace Elements in Calcite Using Solution and Laser Ablation ICP-MS: Calibration to NIST SRM Glass and USGS MACS Carbonate, and Application to Real Landfill Calcite     

Ladislav Strnad  Vojtech Ettler  Martin Mihaljevic  Jindrich Hladil  Vladislav Chrastny 《Geostandards and Geoanalytical Research》2009,33(3):347-355

We report new data on the trace element concentrations of Mg, Cr, Mn, Co, Ni, Cu, Zn, Sr, Cd, Ba, La, Ce, Nd, Pb and U in USGS carbonate reference materials (MACS-1 and MACS-2) and compare solution ICP-MS and LA-ICP-MS trace element determinations on landfill calcites using calibration to different reference materials (MACS-1 and MACS-2 carbonate and NIST SRM 612 glass). Very good agreement (differences below 10% relative) was found between laser ablation and solution ICP-MS data for MACS-1 with higher concentrations of trace elements (values between 100 and 150 μg g⁻¹), with the exception of Cu and Zn. Similarly good agreement was found for MACS-2 with lower trace element concentrations (units to tens of μg g⁻¹), with the exception of Cr, Co and Zn. The MACS-1 reference material for calibration of LA-ICP-MS was found to be extremely useful for in situ determination of trace elements in real-world carbonate samples (landfill calcites), especially those present in calcite in higher concentrations (Mn, Sr, Ba; < 5% RSD). Less accurate determinations were generally obtained for trace elements present at low concentrations (∼ units of μg g⁻¹). In addition, good agreement was observed between the instrument calibration to MACS and NIST SRM 612 glass for in situ measurements of trace elements in landfill calcites K-2, K-3 and K-4 (differences below 15% relative for most elements). Thus, the application of MACS carbonate reference materials is promising and points to the need for the development of new carbonate reference materials for laser ablation ICP-MS.  相似文献   

Initial-value and modal approaches for transient viscoelastic responses with complex viscosity profiles     

Ladislav Hanyk  David A. Yuen  Ctirad Matyska 《Geophysical Journal International》1996,127(2):348-362

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Gravitational potential energy of the Sun     

Milan Burša  Ladislav Křivský  Ondřejka Hovorková 《Studia Geophysica et Geodaetica》1996,40(1):1-8

Summary The gravitational potential energy of the Sun and its corresponding internal energy have been estimated on the basis of the standard model of the Sun's internal structure. It is demonstrated that the principal moment of inertia of the Sun, computed from the model, does not fit the hydrostatic equilibrium limit.  相似文献   

Atmosphärische Niederschläge in Prag-Klementinum (1804–1956)     

Ladislav Křivský 《Studia Geophysica et Geodaetica》1957,1(1):182-192

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Laser Ablation and Solution ICP-MS Determination of Rare Earth Elements in USGS BIR-1G, BHVO-2G and BCR-2G Glass Reference Materials   总被引：2，自引：0，他引：2  

Ladislav Strnad  Martin Mihaljevic  Ondrej Sebek 《Geostandards and Geoanalytical Research》2005,29(3):303-314

Data are reported for rare earth elements (REE) in three geological glass reference materials (BIR-1G, BHVO-2G and BCR-2G) using a UV (266 nm) laser ablation ICP-MS system and the classical (HF-HClO₄) acid decomposition method, followed by conventional nebulisation ICP-MS. External calibration of laser ablation analyses was performed using NIST SRM reference materials with internal standardisation using ²⁹Si and ⁴⁴Ca. Replicate analyses of reference basaltic glasses yielded an analytical precision of 1-5% (RSD) for all the elements by solution ICP-MS and 1-8% (RSD) by laser ablation ICP-MS. The relative differences between the REE concentrations measured by solution and laser ablation ICP-MS compared with the reference values were generally less than 11 % for most elements. The largest deviations occurred for La determined by solution ICP-MS in BIR-1G. The results of both solution and laser ablation ICP-MS agreed well, generally better than 7%, with the exception of La, Pr and Sm in BIR-1G. The measured REE laser ablation data for BIR-1G, BHVO-2G and BCR-2G agreed with the previously published data on these basaltic reference glasses, within a range of 0-10% for most elements. No significant influences were observed for the predicted spectral interferences on some REE isotopes in the analysis of basaltic glasses.  相似文献   

Radium isotopes in river sediments of Czech Republic     

Eduard Hanslík  Eva Kalinov  Martina Brtvov  Diana Ivanovov  Barbora Sedl&#x;ov  Jitka Svobodov  Vra Jedinkov-K&#x;íov  Mark Rieder  Ji&#x;í Medek  Karel Forejt  Ladislav Vondrk  Karel Jahn  Ji&#x;í Jusko 《Limnologica》2005,35(3):177-184

In the Czech Republic, river bottom sediments have been systematically monitored since 1999. In the paper, their radioactive contamination due to uranium mining and milling is assessed. The sediments samples were analyzed by gamma spectrometry. Especially the radium-226 and radium-228 activities were further evaluated.The highest values of the radium-226 activities were found at river profiles where the uranium industry impact was obvious. It turned out that the radium-226 and radium-228 activities ratio is more convenient to assess the level of radium-226 contamination than only the radium-226 activity itself. Based on this hypothesis, the sediment classification scheme for uranium industry contamination was suggested. The natural background activities of radium-226 and radium-228 in the Czech Republic were also evaluated. The case of radium-226 contamination due to the uranium industry was studied in details at the Ploučnice River.  相似文献   

The periodicity of aurorae in the years 1001–1900     

Ivanka Charvátová-Jakubcová  Jaroslav Střeštík  Ladislav Křivský  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1988,32(1):70-77

Summary The sequence of aurorae, observed at latitudes up to 55° between the years 1001 and 1900 was processed by methods of spectral analysis. The same methods were applied to parts of various duration of this interval. The periods predominant in the time series under investigation were determined. In all the selected parts of the interval, these periods are always located within the same frequency band. Their position is related to the periods corresponding to mutual conjunctions of the large planets.

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Removal of trace elements from landfill leachate by calcite precipitation   总被引：1，自引：0，他引：1  

Vojtch Ettler  Olga Zelen  Martin Mihaljevi   Ond&#x;ej &#x;ebek  Ladislav Strnad  Pavel Coufal  Petr Bezdi ka 《Journal of Geochemical Exploration》2006,88(1-3):28

Spontaneous precipitation of secondary calcite (CaCO₃) has been observed in 25 samples of landfill leachate-polluted stream waters. During the 6-month precipitation experiment, the formation of calcite acts as a principal trace-element scavenging process. The concentrations of Fe, Sr, Ba and Mn and other trace elements in solution significantly decreased as calcite formed during the experiments. The PHREEQC-2 geochemical code indicated high supersaturation of the initial leachate-polluted waters with respect to calcite. The chemical/mineralogical study (SEM/EDS, XRD, ICP MS) revealed that this newly formed calcite contains considerable amounts of metals and metalloids removed from solution. Such a geochemical process can be considered to be important for spontaneous decontamination in landfill-affected environments (stream sediments, soils) or landfill technical facilities (settling basins). This removal takes place especially during dry periods with low rain precipitation, when the landfill waters exhibit both higher alkalinity and higher trace element concentrations.  相似文献   

Determination of Gold in e‐Waste Dust Samples and Geological Matrices by ICP‐MS after Extraction by an HClO4‐HBr‐HI‐Aqua Regia Mixture          下载免费PDF全文

Ladislav Strnad  Ondřej Šebek  Marie Fayadová  Jan Vrba 《Geostandards and Geoanalytical Research》2016,40(2):257-266

This study describes two methods (Procedures‐1 and ‐2) for the direct extraction of Au by an inorganic acid mixture (HClO₄‐HBr‐HI‐aqua regia) from complex sample matrices. Standard PTFE jars at 200 °C were used to decompose test portions of 0.5–1 g, with subsequent precise and accurate analysis by ICP‐MS without any other preconcentration or separation. Procedure‐1 decomposed samples effectively without the necessity of leaching with HF and was developed for dust samples from e‐waste (electronic waste) processing; however, testing on geological reference materials showed very good results. The analyses of replicate decompositions (n = 5) from both procedures yielded very good precision (< 5% RSD) for most of the reference materials. The accuracy achieved was better than ± 10%, with the exception of NIST SRM 2782 data from Procedure‐1. Two unknown samples of dust from e‐waste processing (P‐1 and VM‐1) exhibited elevated concentrations of Au (21.31–61.64 μg g^?1) with precision better than 10% (n = 5). The proposed techniques are simple, sensitive and sparing in the use of chemicals, and are designed for a variety of e‐waste dust samples. No significant influences were observed for the predicted spectral interferences on mass ¹⁹⁷Au.  相似文献