A comparison of isotope ratio mass spectrometry and cavity ring‐down spectroscopy techniques for isotope analysis of fluid inclusion water (original) (raw)
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Rapid Communications in Mass Spectrometry, 2013
RATIONALE: The hydrogen and oxygen isotopic analyses (δ 2 H and δ 18 O values) of water trapped within speleothem carbonate (fluid inclusions) have traditionally been conducted utilizing dual-inlet isotope ratio mass spectrometry (IRMS) or continuous-flow (CF)-IRMS methods. The application of cavity ring-down spectroscopy (CRDS) to the δ 2 H and δ 18 O analysis of water in fluid inclusions has been investigated at the University of Miami as an alternative method to CF-IRMS. METHODS: An extraction line was developed to recover water from the fluid inclusions consisting of a crusher, sample injection port and an expansion volume (either 100 or 50 cm 3) directly connected to the CRDS instrument. Tests were conducted to determine the reproducibility of standard water injections and crushes. In order to compare results with conventional analytical methods, samples were analyzed both at the University of Miami (CRDS method) and at the Vrije Universiteit Amsterdam (CF-IRMS method). RESULTS: The analytical reproducibility of speleothem samples crushed on the Miami Device demonstrates an average external standard deviation of 0.5 and 2.0 ‰ for δ 18 O and δ 2 H values, respectively. Sample data are shown to fall near the global meteoric water line, supporting the validity of the method. Three different samples were analyzed at Vrije Universiteit Amsterdam and the University of Miami in order to compare the performance of each laboratory. The average offset between the two laboratories is 0.7 ‰ for δ 18 O and 2.5 ‰ for δ 2 H. CONCLUSIONS: The advantage of CRDS is that the system is a low-cost alternative to CF-IRMS for fluid inclusion isotope analysis. The CRDS method demonstrates acceptable precision and good agreement with results from the CF-IRMS method. These are promising results for the future application of CRDS to fluid inclusion isotope analysis.
Rapid Communications in Mass Spectrometry, 2009
An analytical line for stable isotope analyses of water recovered from fluid inclusions in minerals was built and successfully tested. The line is based on the principle of continuous-flow analysis of water via high-temperature reduction on glassy carbon. It includes a custom-designed set of high-efficiency crushers and a cryo-focusing cell. This paper provides details of the line design and discusses strategies for line conditioning and mitigation of memory effects. The line allows measurements of hydrogen and oxygen isotopes during a single acquisition. The precision of the analyses depends on the amount of water released from the inclusions. The best results are obtained for samples containing at least 0.1–0.2 µL (0.06–0.11 µmol) H2O. For such samples precision is better than 1.5‰ for δD and 0.5‰ for δ18O (1σ). Smaller amounts of water can be measured but at lower precision. Analyses of modern calcite formed under stable conditions in a deep cave allowed assessment of the accuracy of the analyses. The δD values measured in fluid inclusions of this working standard match the δD value of the parent water, and the oxygen isotope values agree within ca. 0.5‰. This indicates that fluid inclusions trapped in calcite at near-ambient temperatures (e.g. speleothems and low-temperatures phreatic calcite) faithfully preserve the original isotopic composition of the parent waters. Copyright © 2009 John Wiley & Sons, Ltd.
Geochemistry, Geophysics, Geosystems
18 O and D of fluid inclusions in carbonates provide insights into temperatures and fluid chemical compositions prevailing during the carbonate precipitation, however various analytical restrictions limit a wider application of this proxy. This paper presents a new fluid inclusions isotopic analytical line coupled to an online cavity ring-down spectrometer that increased the analytical productivity up to ten carbonate samples per working day. This efficiency allowed for the first time to assess the reliability a large set of water samples with size ranging from 0.1 to 1 µL. Good reproducibility (± 0.5 ‰ for 18 O and ± 2 ‰ D; 1) is obtained for water quantity superior or equal to 0.3 L and no evidence of memory effect is found. The line is further tested using two types of natural carbonates: (1) modern speleothems samples from caves for which 18 O and D values of drip water were measured and (2) diagenetic carbonates for which the 18 O of the parent water were independently back-calculated from carbonate clumped isotope 47 measurements. Speleothem fluid inclusion values despite falling close to the Global Meteoritic Water Line are not always representative of the isotopic composition of the parent drip water. Results on diagenetic cements show that the 18 O water values measured in fluid inclusions agree, within 1 %, with the 18 O water independently derived from 47 measurements. Overall, this study confirms the reliability and accuracy of the developed analytical line for carbonate fluid inclusion analyses with a good reproducibility obtained for water quantity above 0.3 L.
Climate of the Past Discussions, 2014
A new online method to analyse water isotopes of speleothem fluid inclusions using a wavelength scanned cavity ring down spectroscopy (WS-CRDS) instrument is presented. This novel technique allows us simultaneously to measure hydrogen and oxygen isotopes for a released aliquot of water. To do so, we designed a new simple line that allows the online water extraction and isotope analysis of speleothem samples. The specificity of the method lies in the fact that fluid inclusions release is made on a standard water background, which mainly improves the δD robustness.
Ore Geology Reviews, 2012
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has become a most powerful technique for the elemental analysis of individual, polyphase inclusions completely enclosed in minerals, be they solid or a solid-liquid-gas mixture at the time of measurement. Simultaneous, accurate quantification of major to ultra-trace element concentrations from Li to U by well-controlled ablation of the entire fluid or melt inclusion content and successful use of largely matrix-independent external calibration protocols are unique features of this method. This contribution reviews fluid inclusion fundamentals relevant for their bulk analysis by LA-ICP-MS and discusses key aspects of the analytical protocol. Emphasis is on figures of merit (precision, accuracy) obtained from the analysis of individual inclusions and fluid inclusion assemblages, and procedures and technical developments to improving data quality are elaborated. A new equation for the calculation of detection limits for LA-ICP-MS analysis is presented, which closely follows IUPAC conventions. Applications are reviewed with emphasis on the use of synthetic fluid inclusions in constraining metal solubility and distribution between co-existing phases. New data for natural bismuth "fluid" inclusions document the seamless transition to melt inclusion analysis by LA-ICP-MS, thus highlighting the fact that the procedures presented here are generally applicable to the analysis of inclusions in complex host minerals. Isotope ratio analysis of individual fluid inclusions by multicollector ICP-MS (MC-ICP-MS) is a recent development that requires fast transient signals to be accurately recorded by instrumentation designed for high-precision static measurements of long-lasting stable ion beams. We address the general principles based on Pb isotopes and review a first application to the Bingham Canyon porphyry Cu-Au ± Mo deposit. A pilot study using about 50 synthetic fluid inclusions containing SRM 987 Sr and variable NaCl, Ca, and Rb concentrations demonstrates that accurate 87 Sr/ 86 Sr isotope ratios can be obtained on an individual Rb-poor fluid inclusion, at absolute 2 σ precisions of 0.0003 to 0.002. A residual trend in 87 Sr/ 86 Sr as a function of the Rb/Sr abundance ratio in the fluid inclusions suggests that interference correction of 87 Rb on mass 87 assuming identical mass bias coefficients for the two elements may be inaccurate; however, the offset can be accurately corrected for by regressing the data to zero 87 Rb. The versatility and detection power of LA-ICP-MS makes this technique the method of choice for solute abundance and isotope ratio analysis of individual fluid inclusions. Significant future progress can be achieved by improvements in ion production, transmission and data recording efficiency and by further improving control on inclusion ablation by pulsed laser beams. Data quantification strategies may also have to be further refined to keep pace with instrumental progress and innovation.
Hydrogen and oxygen isotope standards for the analysis of water inclusions in halite
Geostandards and Geoanalytical Research
Fluid inclusions represent a unique opportunity for a straightforward determination of the chemical and isotopic composition of fluids that composed the hydrosphere and atmosphere over Earth's history. The production of reference materials in the laboratory is needed to monitor and to validate the determination of hydrogen and oxygen isotope compositions of water inclusions. We propose a protocol leading to the experimental synthesis of halite crystals that contain water inclusions whose dD and d 18 O values can be related to those of surrounding evaporating waters where the crystals grew. Corrections to isotopic measurements were performed by applying an orthogonal projection of the raw data to the water evaporation trajectory line whose slope can be predicted by taking into account the parameters developed in the linear resistance model of . Several hundreds of grams of halite reference material can be produced rapidly (within 2 d) at a low cost and can be stored within a vacuum desiccator at ambient temperature over several months or years. The described method is especially useful for the analysis of anhydrous salts and the interpretation of isotopic fractionations that operate within the surficial water cycle.
Sedimentology, 2014
The Denizli Basin is a fault-bounded Neogene-Quaternary depression located in the Western Anatolian Extensional Province, Western Turkey. The basin is a unique geological site with abundant active and fossil (Quaternary) travertine and tufa deposits. Fluid inclusion microthermometry and isotopic analysis were applied to study the genesis of the Ballık fossil travertine deposits, located in the southeastern part of the basin. Microthermometry on fluid inclusions indicates that the main travertine precipitating and cementing fluids are characterized by low-salinity (<0.7 wt% NaCl equivalent) and variable temperature that cluster at <50°C and ca 100°C. Fluids of meteoric origin have been heated by migration to the deeper subsurface, possibly in a local high geothermal gradient setting. A latter uncommon cementation phase is related to a fluid with a significantly higher salinity (25.5 to 26.0 wt% bulk). The fluid obtained its salinity by interaction with Late Triassic evaporite layers. Sr isotopes indicate that the parent carbonate source rock of the different travertine precipitates is very likely to be the Triassic limestone of the Lycian Nappes. Carbon isotopes suggest that the parent CO 2 gas originated from thermal decarbonation of the Lycian limestones with minor contributions of magmatic degassing and organic soil CO 2. Oxygen isotopes confirm the meteoric origin of the fluids and indicate disequilibrium precipitation because of evaporation and degassing. Results were integrated within the available geological data of the Denizli basin in a generalized travertine precipitation model, which enhanced the understanding of fossil travertine systems. The study highlights the novel application of fluid inclusion research in unravelling the genesis of continental carbonates and provides several recommendations for hydrocarbon exploration in travertine-bearing sedimentary basins. The findings suggest that travertine bodies and their parent carbonate source rocks have the This article is protected by copyright. All rights reserved. potential to constitute interesting subsurface hydrocarbon reservoirs.
ISOTOPE TRACING IN GROUNDWATER APPLICATIONS
Isotope methods in hydrogeological studies of Finnish shallow glacigenic formations have been developed and applied at the Geological Survey of Finland (GTK) since the late 1990s. The Laboratory for Isotope Geology has analyzed oxygen and hydrogen isotopes in water samples on a routine basis since 1995, and the isotopic composition of inorganic carbon and strontium dissolved in water since 2000. The first detailed records on spatial and annual variability in the isotopic composition of precipitation and groundwaters in Finland were generated during 1995 to 2005. GTK has three active precipitation stations related to the Global Network of Isotopes in Precipitation (GNIP) programme operated by the IAEA. Isotope "fingerprinting", based on the isotopic difference between interacting water reservoirs, has been useful in several applied studies related to water management, especially artificial recharge (AR). At Tuusula Waterworks in southern Finland, the isotope ratios of oxygen and hydrogen have been utilized to calculate the mixing ratios between local groundwater and infiltrated lake water, and the carbon isotope method to quantify the processes of organic matter removal in artificial groundwater recharge. To understand the response of the natural groundwater system to artificial recharge and the mixing of infiltrated water with local groundwater, knowledge of the geochemical baseline and isotopic characteristics of the aquifer is essential. In the Virttaankangas groundwater formation, SW Finland, isotopic applications in AR have had a significant role in the planning of infiltration and monitoring of the active water plant, as well as assisting in the calibration of groundwater flow model. New isotope approaches for hydrogeology are being tested using the facilities of the Finnish Isotope Geology Laboratory (SIGL). Separation method for cations such as lithium, magnesium, calcium, strontium, lead and uranium are currently under development. The automated separation methods would significantly reduce the throughput time of samples. In contrast to oxygen and hydrogen, the isotopic differences in dissolved components in water are inherited from organic and inorganic atmospheric, industrial and anthropogenic sources, together with weathering processes during the interaction between minerals, soil and water.