Low Concentrations Of Re Research Articles

Evaluation of Re–Os geochronology and Os isotope fingerprinting of Late Cretaceous terrestrial oils in Taranaki Basin, New Zealand

The rhenium-osmium (Re–Os) isotope system has been applied to several marine and lacustrine petroleum systems worldwide, showing good potential for dating crude oils and correlating them to their source rocks. Here we explore the applicability of the Re–Os geochronometer and Os isotope fingerprinting to terrestrial oils by comparing the Re and Os systematics of Late Cretaceous terrestrial oils from Taranaki Basin, New Zealand, and their correlated coaly source rocks. Comparison is also made with selected Late Cretaceous–Paleocene marine oils and source rocks with varying levels of terrestrial organic matter input.The asphaltene fractions of nine genetically related terrestrial oils from the Maui, Maari-Manaia and Tui Area fields in offshore Taranaki Basin contain low concentrations of Re (0.18–0.45 ppb) and 192Os (1.3–12.7 ppt) comparable to their correlated Late Cretaceous coaly source rocks (Rakopi and North Cape formations; Re 0.19–0.37 ppb, 192Os 5.3–9.6 ppt). The Re and 192Os concentrations in these terrestrial oils are generally one to two orders of magnitude lower than those in marine-sourced oils from the Kora Field in offshore Taranaki Basin and surface seeps in East Coast Basin.The 187Re/188Os and 187Os/188Os ratios of the terrestrial oils failed to yield a precise Re–Os isochron age. We attribute this to: (1) insufficient homogenisation of oils with widely variable initial 187Os/188Os (Osi) values inherited from thick, coaly source rock intervals (up to about 2700 m) within the Maui sub-basin and northern Kahurangi Trough kitchens; (2) insufficient spread of 187Re/188Os values (only 275 units); (3) insufficient time since oil expulsion (modelled to be from approximately 10 Ma to the present day) for the evolution of an isochron; and (4) possible effects of water washing of the oil columns. Although all of the studied oils are water-washed to varying degrees, there is no definitive evidence that water washing has disturbed the Re–Os systematics.The Osi values for the studied terrestrial oils inherited at the modelled time of oil expulsion (approximately 10 Ma) display a wide range (0.47–1.14) and do not provide a unique fingerprint of their Late Cretaceous coaly source rock formations. Osmium isotope compositions therefore appear to have limited potential for broad oil-source rock correlation within the predominantly coal-sourced petroleum systems of Taranaki Basin. The Osi values may, however, provide useful distinction of the terrestrial oils emanating from the Kahurangi Trough (Tui Area oils) from those of the Maui sub-basin (Maui and Maari-Manaia oils) based on the significantly more radiogenic values of the Tui Area oils (0.84–1.14 compared with 0.47–0.65 from Maui and Maari-Manaia oils). Overall, this study has provided useful insights into the potential application of the Re–Os isotope system to terrestrial, coal-sourced petroleum systems.

INFLUENCE OF ORGANIC MATTER ON Re-Os DATING OF SULFIDES: INSIGHTS FROM THE GIANT JINDING SEDIMENT-HOSTED Zn-Pb DEPOSIT, CHINA

Abstract This study evaluates the effect of organic matter impurities on pyrite Re-Os dating, using the giant Jinding sediment-hosted Zn-Pb deposit in China as an example. The Jinding deposit is hosted in a Paleocene evaporite dome that was a hydrocarbon reservoir before mineralization. Pyrite in Jinding formed in two stages: pre-ore (py1) and syn-ore (py2). Two types of py1 are recognized, organic matter-free and organic matter-bearing. The organic matter-free py1 contains homogeneously distributed low concentrations of Re (<2.5 ppb) that yields an isochron age of 51 ± 1 Ma (mean square of weighted deviates [MSWD] = 3.2). This date is interpreted to be the age of py1 formation. The organic matter-bearing py1 contains organic matter inclusions trapped during py1 growth and synchronous with bacterial reduction of sulfate. Elemental mapping with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) shows that the organic matter inclusions have Re signals 1 to 4 orders of magnitude higher than those of pyrite, revealing that organic matter is the major host for Re. Such pyrite separates contain 37 to 1,145 ppb Re. The Re-Os data of organic matter-bearing py1 yield an isochron age of 72.9 ± 0.5 Ma (MSWD = 0.2). This age is older than the actual py1 formation age of 51 ± 1 Ma but overlaps with previously dated bitumen Re-Os isochron age of 68 ± 5 Ma at Jinding, indicating that organic matter inclusions can significantly influence the Re-Os dates of pyrite and likely other sulfides. This study demonstrates that in order to date sulfides formed in organic-rich environments using the Re-Os method, it is necessary to determine the distribution of Re in samples using detailed petrography and LA-ICP-MS trace element mapping plus spot analysis.

Geochemistry of Rhenium and Other Trace Elements in Molybdenite, Sar Cheshmeh Porphyry Cu‐Mo Deposit, Iran

AbstractLA‐ICP‐MS analysis of molybdenite from the Sar Cheshmeh porphyry Cu‐Mo deposit (PCD), Iran, shows moderate concentration of Re (average ∼207 ppm) and low concentration of chalcogenides (average of Pb + Te + Bi, ∼31 ppm) as well as metalloids (average of As + Sb + Ge, ∼4.5 ppm). The early‐formed quartz–molybdenites associated with potassic alteration are characterized by moderately low concentration of Re (21–215 ppm with an average of 83 ppm), whereas the transitional quartz–molybdenite veins related to the sericitic stage of mineralization contain more Re (62–465 ppm, with an average of 207 ppm). In contrast, the late‐formed quartz–molybdenite veins associated with phyllic alteration show the highest concentration of Re (up to 1273 ppm with an average of 395 ppm). Gradual increase in Re content of molybdenites deposited throughout the evolution of the porphyry system is probably related to elevated ƒO2 and acidic conditions of the ore fluids governing the transitional and late stage of mineralization, when compared to the moderately low ƒO2 and basic conditions of the ore fluids precipitating the low‐Re molybdenites associated with potassic alteration. The mixed mantle/crustal source of the ore‐related magma and its fractionated composition in Sar Cheshmeh are consistent with magmatic conditions for the formation of Mo‐rich and Re‐poor PCDs in the world.

Technetium-99 decontamination from radioactive wastewater by modified bentonite: batch, column experiment and mechanism investigation

Technetium-99 (99Tc), as one of the important high-yield fission products, poses a significant threat to the environment and human health due to its radiotoxicity, long half-life, high solubility and mobility in the environment. Thus, removal of 99TcO4− from radioactive wastewater is considerably imminent for waste disposal and environment conservation. In this work, Hexadecylpyridinium Chloride Monohydrate modified bentonite (HDPy-bent) was synthesised and used as an adsorbent to remove 99TcO4−. The adsorption behaviours of ReO4− as an analogue for TcO4− were investigated as functions of contact time, solution pH, initial concentration, and competing anions using batch techniques. It is demonstrated that the HDPy-bent showed an excellent adsorption ability for ReO4− at the pH range of 2–11, fast adsorption kinetic (reaching equilibrium within 3 min at room temperature), and maintains desirable ReO4− adsorption in the presence of concomitant anions at an excessive concentration of 500 times (Cl−, HCO3−, NO3−, CO32−, SO42− and PO43−). As for adsorption mechanism, we propose the anion exchange process at low concentration of Re(VII) and precipitation reaction at high concentration, while the driving force of the high ReO4− adsorption ability is the interaction between ReO4− anion and pyridinium ring of HDPy+, which is confirmed by density functional theory (DFT) simulations. Additionally, DFT studies also shed light on the adsorption structure of HDPy+/ReO4− and the origin of adsorption selectivity. Moreover, four adsorption-desorption cycles suggest that the HDPy-bent has good durability and reusability. Furthermore, ReO4− can be removed completely and recovered fractionally by using the chromatography column packed with HDPy-bent from simulated groundwater samples. The work presented herein demonstrates a low-cost adsorbent which can efficiently remove 99Tc from contaminated water.

The micro-mechanism of rhenium promoting the formation of stacking faults in the Ni-based model single crystal superalloys

It is important and necessary to understand the micro-mechanism of rhenium (Re) effect in the deformation process. The in-situ tensile experiments of Ni–Al and Ni–Al-Re model single crystal superalloys have been carried out in scanning electron microscope at 750 °C. It is found that Re can promote the complex stacking fault (CSF) formation, which is similar to the previous results after tensile experiments at room temperature. The micro-mechanism of Re promoting the CSF formation has been investigated by means of advanced probe-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. The local high concentration of Re is observed at CSF regions after tensile experiments both at room temperature and 750 °C. The first principles calculation results further indicate that low concentration of Re increases CSF energy, while high concentration of Re decreases CSF energy, which is consistent with the experimental results.

Ginsenosides regulate adventitious root formation in Panax ginseng via a CLE45–WOX11 regulatory module

Adventitious root branching is vital to plant growth and regeneration, but the regulation of this process remains unclear. We therefore investigated how ginsenosides regulate adventitious root branching in Panax ginseng. Cell proliferation and adventitious root branching were decreased in the presence of ginsenoside Rb1 and a high concentration of ginsenoside Re, but increased when treating with a low concentration of Re. Moreover, the exogenous application of a synthetic dodeca-amino acid peptide that has a CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) motif corresponding to PgCLE45 retarded root growth in both ginseng and Arabidopsis. The root Re levels and the expression of the DDS, CYP716A47, and CYP716A53 genes that encode enzymes involved in ginsenoside synthesis were decreased in the presence of PgCLE45. The expression profiles of PgWOX and PgCLE genes were determined to further investigate the CLE-WOX signaling pathway. The levels of PgWOX11 transcripts showed an inverse pattern to PgCLE45 transcripts. Using yeast one-hybrid assay, EMSA, and ChIP assay, we showed that PgWOX11 bound to the PgCLE45 promoter, which contained the HD motif. Transient expression assay showed that PgWOX11 induced the expression of PgCLE45 in adventitious roots, while PgCLE45 suppressed the expression of PgWOX11. These results suggest that there is a negative feedback regulation between PgCLE45 and PgWOX11. Taken together, these data show that ginsenosides regulate adventitious root branching via a novel PgCLE45-PgWOX11 regulatory loop, providing a potential mechanism for the regulation of adventitious root branching.

Application of addition HClO4 to improve the dissolution process and sensitivity of Os for low-concentration of Os in pyrite

The rhenium (Re) and osmium (Os) isotope systems have long been recognized as effective tools to directly date mineralization and trace the source of metals. In general, 0.4 g of pyrite was dissolved by 11 mL of inverse aqua regia in a 30-mL Carius tube. Larger volumes of acids and a larger Carius tube were required if the sample weight was over 0.4 g. Herein we present an improved dissolution process of the Carius tube digestion method by adding HClO4 to dissolve larger sample weights in smaller volumes of acid. This approach is more suitable for determining low concentrations of Os in metal sulfides. In detail, 0.4 g of pyrite was completely dissolved in a mixture of 1 mL of HClO4 and 3 mL of inverse aqua regia. Notably, addition of 1 mL of HClO4 to 8 mL of inverse aqua regia significantly increases the amount of sample from 0.4 to 0.8 g. Based on our data, while the sample weight was no >0.8 g, addition of 1 mL of HClO4 to inverse aqua regia can not only improve the dissolving capacity significantly, but also avoid Carius tube explosion. Furthermore, the dissolving capacity of HClO4-inverse aqua regia method is much higher than that of H2O2-inverse aqua regia method, which is a typical digestion method for Re-Os dating. This method was certified by reference materials (HLP and JDC). In brief, this new method allows dissolution of larger amounts of sample while consuming less acid. Therefore, this method has more potential for determining low concentrations of Re and Os in metal sulfides.

Influence of Re Concentration on the Mechanical Properties of Tungsten Borides from First-Principles Calculations

Tungsten borides are promising high-temperature materials. However, the structure and hardening mechanisms of tungsten boride are still great challenges. To solve the problems, we apply the first-principles method to study the structure of WB3 and explore the influence of alloying element Re on the mechanical properties of WB3. The calculated Vickers hardness of WB3 is 39.1 GPa. We further find that a low concentration of Re can improve the hardness of WB3, which is in good agreement with the experimental result. However, the hardness and elastic properties of WB3 decrease gradually with increasing Re concentration. The calculated results show that the structure and hardness of WB3 are attributed to the B–B hexagonal prism. A high concentration of Re weakens the charge interaction between the B–B atoms, and reduces the mechanical properties of WB3. Therefore, we can adjust the alloy concentration to improve the Vickers hardness of transition metal borides.

Re[sbnd]Os and S isotopic constraints on the origins of two mineralization events at the Tangdan sedimentary rock-hosted stratiform Cu deposit, SW China

The Tangdan stratiform Cu deposit in the Kangdian region of South China is hosted in sedimentary rocks of the late Paleoproterozoic to early Mesoproterozoic Dongchuan Group. Orebodies mainly occur in dolostone and black shale above a thick sequence of hematitic sandstone and siltstone. Mineralization consists mainly of bedding-parallel stratiform ores, with minor amounts of discordant vein-type ores. Both stratiform and vein-type ores are composed of bornite and chalcopyrite with minor chalcocite and digenite, associated with gangue minerals including ankerite, dolomite, calcite, and quartz.Cu-sulfides from vein-type ores contain ~122–293ppb Re, much higher than those of stratiform ores (~0.6–14ppb Re). They have highly radiogenic Os with ReOs model ages ranging from 1413 to 1457Ma and a weighted mean ReOs model age of 1432±19Ma (2σ, MSWD=0.30), which is within uncertainty in agreement with isochron ages of 1401±30Ma (2σ, MSWD=0.67) and 1397±71Ma (2σ, MSWD=0.22) using 187Re/188Os versus 187Os/188Os and 187Re versus 187Os regression, respectively. In contrast, sulfides from stratiform ores did not yield meaningful model ages due to the extremely low concentrations of Re and radiogenic Os. However, early studies have shown that the stratiform ores were likely formed at ~1700Ma during the diagenesis of the host strata.Sulfides from the vein-type ores have δ34S values ranging from −15‰ to −8‰, significantly lower than those of stratiform ores (−3‰ to +10‰), suggesting that organic matter may have been involved in the formation of the vein-type ores. Contrasting ReOs and S isotopes suggest that the two types of ores at the Tangdan deposit were likely formed from different ore-forming fluids. We propose that stratiform ores were precipitated from basinal fluids during the early evolution of the rift basin, whereas the vein-type ores were formed due to a much younger thermal event during which hydrothermal fluids interacted with overlying black shale to account for the high Re and negative δ34S values. This study demonstrates that ReOs isotopes of sulfides can be used to study the origin of hydrothermal system.

An improved Carius tube technique for determination of low concentrations of Re and Os in pyrites

A simple and highly selective analytical method is developed for Re–Os dating in hydrothermal pyrites. Pyrites were first digested with HNO3 in a 120 ml Carius tube. The released additional gas and a small portion of volatile Os (∼6% of total Os) were collected by 10 mol l−1 of HCl in an ice-water bath. After the sulfides were totally reacted with HNO3, the HCl solution containing all the released Os was transferred back to the Carius tube. The sample was further digested in aqua regia at 200 °C for about 10 h in a sealed Carius tube. Because prior digestion in an open Carius tube removed the additional gas, this improved technique allows increasing the sample mass to about 3 g, which is vital for Re–Os dating in Re and Os poor hydrothermal pyrites. Os was separated from the matrix by distillation and Re by anion exchange resin. The results obtained for molybdenite reference materials, JDC and HLP mixed with 3 g pyrite are in good agreement with certified values. Despite very low concentrations of Re and Os, the pyrite yields excellent repeatability and can be used for Re and Os poor hydrothermal pyrites.

Precise determination of rhenium isotope composition by multi-collector inductively-coupled plasma mass spectrometry

We present rhenium (Re) isotope data for commercially available Re reference materials SRM 989, SRM 3143, and Alfa Aesar Specpure®Re, as well as two Re solutions made in-house from perrhenic acid and zone-refined flattened-wire ribbon from H. Cross Company. Data were generated by MC-ICPMS (Thermo Fisher Scientific NEPTUNE) using standard-bracketing combined with a tungsten (W) external correction. Intermediate measurement precision (i.e. the precision for similar analytical procedures and measurement conditions on the same instrument over time) is ±0.05‰ (2s) for analyte solution concentrations of 20 ng g−1Re and 70 ng g−1W; intermediate precision decreases to ±0.1‰ (2s) when respective analyte concentrations are halved to 10 ng g−1 and 35 ng g−1. The five Re solutions exhibit an isotopic range of 0.29‰, providing the first evidence for stable isotope fractionation of Re. Data are also presented for the Devonian Ohio Shale standard USGS SDO-1; intermediate precision for this natural material (±0.13‰, 2s) is comparable to solution standard precisions at equivalent concentrations (10 ng g−1Re, 35 ng g−1W). Analysis of geochemical materials introduces additional concerns. The low concentration of Re in most materials limits these analyses to Re-rich substrates. Isotopic fractionation occurring during chromatographic purification is nullified by quantitative recovery, and the sample matrix does not introduce fractionation artifacts. Isobaric interference from radiogenic 187Os can be effectively removed by sparging sample solutions prior to analysis.

Pinning enhancement by heterovalent substitution inY1−xRExBa2Cu3O7−δ

The intragrain pinning in high-Tc superconductor compounds Y1−xRExBa2Cu3O7−δ with low concentration of RE (La, Ce, Pr) was investigated. Magnetic and transportmeasurements reveal that the pinning is maximal for the concentration of heterovalent REsuch that the average distance between the impurity ions in the plane of rare-earthelements is close to the diameter of Abrikosov vortices in YBCO.

Hydrothermal synthesis and luminescent properties of [formula omitted]: RE ( RE=Eu, Tb)

The BaBeF 4 powder has been hydrothermally synthesized from the double system. The effects of factors such as the ratio of initial reaction, pH value, reaction temperature and time were investigated. Moreover, the BaBeF 4 : RE ( RE=Eu, Tb) phosphors were prepared by the hydrothermal method. Further, they were characterized by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis, infrared spectroscopy and X-ray photoelectron spectroscopy. The luminescent properties were investigated by the luminescence spectrometer. The results show that the molar ratio and pH in the initial reaction mixture associated with the reaction temperature dominate the crystallization of the products. The products are air stable. XPS confirms the oxygen content of those products is very low. BaBeF 4 : RE obtained was pure phase of BaBeF 4 . It indicates that doping a low concentration of RE 3 + ions could not change the structure. In the co-doped Eu 3 + and Tb 3 + system, Eu 3 + , Tb 3 + and Eu 2 + are observed in one matrix. These phenomena can be explained using an electron transfer theory. These RE ions occupy the sites of Ba 2 + in BaBeF 4 .

Precise ReOs determinations and systematics of iron meteorites

The ReOs system for samples of FeNi, sulphide, and phosphide from iron meteorites was investigated. Techniques were developed which yield reproducible analyses for Re/Os at the 2%‰ level and which permit complete isotopic exchange between sample and tracer, as is necessary for concentration measurements of Re and Os by isotope dilution. High precision osmium and rhenium isotope data have been obtained using negative ion thermal ionization, with ionization efficiencies of up to 10% for Os and 20% for Re, both for normals and for Re and Os extracted from the samples. Replicate analyses of Re/Os are in good agreement, within ±2.5%o. The results show a well defined correlation line on a 187Re- 187Os evolution diagram for iron meteorites from groups IAB, IIAB, IIIAB, IVA, and IVB, all taken together. This correlation line yields a slope of 0.07863 ± 0.00031 (2σ) and initial 187Os/ 188Os = 0.09560 ± 0.00018 (2σ). If the individual groups of iron meteorites for which there is sufficient dispersion in Re/Os are considered, data on the IIAB and on the IVA irons appear to indicate a difference in age of 60 ± 45 Ma, with the IVA group being older. This age difference is qualitatively the same as obtained for PdAg data but is larger. Sulphides from two IAB iron meteorites show extremely low concentrations of Re and Os and indicate that Re and Os are not partitioned into this phase during planetary differentiation. There is evidence for recent element remobilization or contamination, corresponding to relative enrichment of Re or loss of Os in the sulphides. Schreibersites contain small but significant amounts of Re and Os, with high Re/Os relative to the metal phases and with 187Os/ 188Os much more radiogenic than in the metal. Model ages for the Schreibersites are relatively young (4.3–3.5 AE) and indicate that the Schreibersites were open-systems for ReOs at least 0.5–1 AE after the original formation of the iron meteorites. It now appears possible to use metal- schreibersite pairs to determine internal isochrons. Based on the schreibersite model ages, the cooling rates for the two IAB meteorites are estimated to be ∼ 1°C/Ma, more than an order of magnitude lower than the most recently determined metallographic cooling rates for IAB irons (Herpfer et al., 1994).