Cassiterite oxygen isotopes in magmatic-hydrothermal systems: in situ microanalysis, fractionation factor, and applications

2021 ◽  
Author(s):  
Yang Li ◽  
Sheng He ◽  
Rong-Qing Zhang ◽  
Xian-Wu Bi ◽  
Lian-Jun Feng ◽  
...  
Keyword(s):  
Oxygen Isotopes ◽  
Hydrothermal Systems ◽  
Fractionation Factor

scholarly journals Fingerprinting Paranesti Rubies through Oxygen Isotopes

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 91 ◽  
Author(s):  
Kandy Wang ◽  
Ian Graham ◽  
Laure Martin ◽  
Panagiotis Voudouris ◽  
Gaston Giuliani ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Oxygen Isotopes ◽  
Narrow Range ◽  
Mean Value ◽  
Ionization Mass ◽  
Crustal Structures ◽  
In Situ Methods ◽  
Secondary Ionization Mass Spectrometry ◽  
Laser Fluorination

In this study, the oxygen isotope (δ18O) composition of pink to red gem-quality rubies from Paranesti, Greece was investigated using in-situ secondary ionization mass spectrometry (SIMS) and laser-fluorination techniques. Paranesti rubies have a narrow range of δ18O values between ~0 and +1‰ and represent one of only a few cases worldwide where δ18O signatures can be used to distinguish them from other localities. SIMS analyses from this study and previous work by the authors suggests that the rubies formed under metamorphic/metasomatic conditions involving deeply penetrating meteoric waters along major crustal structures associated with the Nestos Shear Zone. SIMS analyses also revealed slight variations in δ18O composition for two outcrops located just ~500 m apart: PAR-1 with a mean value of 1.0‰ ± 0.42‰ and PAR-5 with a mean value of 0.14‰ ± 0.24‰. This work adds to the growing use of in-situ methods to determine the origin of gem-quality corundum and re-confirms its usefulness in geographic “fingerprinting”.

scholarly journals Re-Evaluating the Age of Deep Biosphere Fossils in the Lockne Impact Structure

Geosciences ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 202 ◽  
Author(s):  
Mikael Tillberg ◽  
Magnus Ivarsson ◽  
Henrik Drake ◽  
Martin J. Whitehouse ◽  
Ellen Kooijman ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Crystalline Rock ◽  
Hydrothermal Systems ◽  
Fungal Colonization ◽  
Precambrian Basement ◽  
Impact Event ◽  
Deep Biosphere ◽  
Microbial Ecosystems ◽  
The Impact

Impact-generated hydrothermal systems have been suggested as favourable environments for deep microbial ecosystems on Earth, and possibly beyond. Fossil evidence from a handful of impact craters worldwide have been used to support this notion. However, as always with mineralized remains of microorganisms in crystalline rock, certain time constraints with respect to the ecosystems and their subsequent fossilization are difficult to obtain. Here we re-evaluate previously described fungal fossils from the Lockne crater (458 Ma), Sweden. Based on in-situ Rb/Sr dating of secondary calcite-albite-feldspar (356.6 ± 6.7 Ma) we conclude that the fungal colonization took place at least 100 Myr after the impact event, thus long after the impact-induced hydrothermal activity ceased. We also present microscale stable isotope data of 13C-enriched calcite suggesting the presence of methanogens contemporary with the fungi. Thus, the Lockne fungi fossils are not, as previously thought, related to the impact event, but nevertheless have colonized fractures that may have been formed or were reactivated by the impact. Instead, the Lockne fossils show similar features as recent findings of ancient microbial remains elsewhere in the fractured Swedish Precambrian basement and may thus represent a more general feature in this scarcely explored habitat than previously known.

scholarly journals Volcanic activity and gas emissions along the South Sandwich Arc

2020 ◽  
Vol 83 (1) ◽  
Author(s):  
Emma J. Liu ◽  
Kieran Wood ◽  
Alessandro Aiuppa ◽  
Gaetano Giudice ◽  
Marcello Bitetto ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Volcanic Activity ◽  
Emission Rate ◽  
Tectonic Setting ◽  
Hydrothermal Systems ◽  
Molar Ratio ◽  
The South ◽  
Gas Emissions ◽  
Volcanic Arc

AbstractThe South Sandwich Volcanic Arc is one of the most remote and enigmatic arcs on Earth. Sporadic observations from rare cloud-free satellite images—and even rarer in situ reports—provide glimpses into a dynamic arc system characterised by persistent gas emissions and frequent eruptive activity. Our understanding of the state of volcanic activity along this arc is incomplete compared to arcs globally. To fill this gap, we present here detailed geological and volcanological observations made during an expedition to the South Sandwich Islands in January 2020. We report the first in situ measurements of gas chemistry, emission rate and carbon isotope composition from along the arc. We show that Mt. Michael on Saunders Island is a persistent source of gas emissions, releasing 145 ± 59 t day−1 SO2 in a plume characterised by a CO2/SO2 molar ratio of 1.8 ± 0.2. Combining this CO2/SO2 ratio with our independent SO2 emission rate measured near simultaneously, we derive a CO2 flux of 179 ± 76 t day−1. Outgassing from low temperature (90–100 °C) fumaroles is pervasive at the active centres of Candlemas and Bellingshausen, with measured gas compositions indicative of interaction between magmatic fluids and hydrothermal systems. Carbon isotope measurements of dilute plume and fumarole gases from along the arc indicate a magmatic δ13C of − 4.5 ± 2.0‰. Interpreted most simply, this result suggests a carbon source dominated by mantle-derived carbon. However, based on a carbon mass balance from sediment core ODP 701, we show that mixing between depleted upper mantle and a subduction component composed of sediment and altered crust is also permissible. We conclude that, although remote, the South Sandwich Volcanic Arc is an ideal tectonic setting in which to explore geochemical processes in a young, developing arc.

scholarly journals In Situ Electrochemical Study of the Growth Kinetics of Passive Film on TC11 Alloy in Sulfate Solution at 300 °C/10 MPa

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1135 ◽  
Author(s):  
Lei Zha ◽  
Heping Li ◽  
Ning Wang
Keyword(s):  
Passive Film ◽  
Growth Kinetics ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Sulfate Solution ◽  
Open Circuit ◽  
Hydrothermal Systems ◽  
Wide Range ◽  
Kinetics Of

TC11 alloy is a promising structural material, and has a wide range of applications in many corrosive and high temperature hydrothermal systems. The passive film has an important influence on its electrochemical behavior. In this study, in-situ electrochemical methods (that is, open circuit potential (OCP), linear polarization (LP) and electrochemical impedance spectroscopy (EIS)) were used to monitor the long period electrochemical behavior of TC11 alloy in 0.01 M Na2SO4 solution at 300 °C/10 MPa. The growth kinetics of the passive film was mainly studied. The correlation between the evolution of the electrochemical behavior and the growth of the oxide film was discussed. The results showed that although the OCP gradually stabilized after twenty thousand seconds, henceforth the polarization resistance (Rp) was still increasing due to the thickening of the passive film. An equivalent circuit was proposed to fit the EIS experimental data, leading to determination of film capacitance and film resistance. Besides, the electrochemical data was interpreted in terms of the point defect model (PDM). The EIS results are consistent with the Rp results.

Solution to an enigma: Explaining the slope of carbon vs. oxygen isotopic disequilibrium in biogenic and inorganic carbonates

2020 ◽  
Author(s):  
Richard Zeebe ◽  
Lauren Yumol ◽  
Joji Uchikawa
Keyword(s):  
Oxygen Isotopes ◽  
Underlying Mechanism ◽  
Ph Control ◽  
Solution Ph ◽  
Fractionation Factor ◽  
Oxygen Isotopic ◽  
Vital Effects ◽  
Widespread Phenomenon ◽  
Kinetic Effects ◽  
Isotopic Disequilibrium

<p>A widespread phenomenon in biogenic and inorganic carbonates that are formed out of isotopic equilibrium is a nearly ubiquitous co-variation (slope) of carbon vs. oxygen isotopes, in e.g., speleothem and cryogenic carbonates, shells and skeletons of foraminifera, corals etc. For proxy calibrations, it is critical to understand such isotope variations (often labeled kinetic or vital effects) in proxies widely used for paleo-reconstructions. Given that this phenomenon is observed in inorganic carbonates and biogenic carbonates across different phyla suggest a common underlying mechanism, possibly independent of biological controls, that is, likely of inorganic origin. Here we present results from laboratory experiments on synthetic carbonate precipitation to constrain the kinetic isotope fractionation factor (KFF) of carbon and oxygen during CO2 hydration. We used an experimental setup similar to that of an earlier study but with important modifications and tight temperature and pH control. The average d13C and d18O values of our carbonate samples (BaCO3) produced at 25 deg C and pH = 8.0 (NBS) are -29.7 +- 0.71 per mil (VPDB) and 18.8 +- 0.56 per mil (VSMOW), respectively. From the isotope data, we calculate our experimental 13KFF and 18KFF, which refer to the 13C/12C and 18O/16O fractionation between CO2(g) and BaCO3, where the d13C and d18O values of CO2(g) were calculated using known equilibrium fractionation factors. Our results show that our KFFs are the largest values compared to previously reported experimental KFFs (except for one study), suggesting that our values are closest to the full isotopic disequilibrium during CO2 hydration. Based on our KFFs, we will present the expected slope of carbon vs. oxygen isotopic disequilibrium from kinetic effects during CO2 hydration. We will also discuss the expected slope from equilibrium effects of solution pH on oxygen isotopes. Comparison with field and culture data will reveal the origin of the slope of carbon vs. oxygen isotopic disequilibrium in biogenic and inorganic carbonates.</p>

scholarly journals Stable Isotope Fractionation Caused by Glycyl Radical Enzymes during Bacterial Degradation of Aromatic Compounds

2004 ◽  
Vol 70 (5) ◽  
pp. 2935-2940 ◽  
Author(s):  
Barbara Morasch ◽  
Hans H. Richnow ◽  
Andrea Vieth ◽  
Bernhard Schink ◽  
Rainer U. Meckenstock
Keyword(s):  
Stable Isotope ◽  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Toluene Degradation ◽  
Fractionation Factor ◽  
Glycyl Radical ◽  
Stable Isotope Fractionation ◽  
Benzylsuccinate Synthase ◽  
Glycyl Radical Enzyme

ABSTRACT Stable isotope fractionation was studied during the degradation of m-xylene, o-xylene, m-cresol, and p-cresol with two pure cultures of sulfate-reducing bacteria. Degradation of all four compounds is initiated by a fumarate addition reaction by a glycyl radical enzyme, analogous to the well-studied benzylsuccinate synthase reaction in toluene degradation. The extent of stable carbon isotope fractionation caused by these radical-type reactions was between enrichment factors (ε) of −1.5 and −3.9, which is in the same order of magnitude as data provided before for anaerobic toluene degradation. Based on our results, an analysis of isotope fractionation should be applicable for the evaluation of in situ bioremediation of all contaminants degraded by glycyl radical enzyme mechanisms that are smaller than 14 carbon atoms. In order to compare carbon isotope fractionations upon the degradation of various substrates whose numbers of carbon atoms differ, intrinsic ε (εintrinsic) were calculated. A comparison of εintrinsic at the single carbon atoms of the molecule where the benzylsuccinate synthase reaction took place with compound-specific ε elucidated that both varied on average to the same extent. Despite variations during the degradation of different substrates, the range of ε found for glycyl radical reactions was reasonably narrow to propose that rough estimates of biodegradation in situ might be given by using an average ε if no fractionation factor is available for single compounds.

scholarly journals Hydrothermal synthesis of long-chain hydrocarbons up to C24 with NaHCO3-assisted stabilizing cobalt

2021 ◽  
Vol 118 (51) ◽  
pp. e2115059118
Author(s):  
Daoping He ◽  
Xiaoguang Wang ◽  
Yang Yang ◽  
Runtian He ◽  
Heng Zhong ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Hydrothermal Synthesis ◽  
Co Adsorption ◽  
Hydrothermal Systems ◽  
Hydrothermal Conditions ◽  
Hydrocarbon Synthesis ◽  
Emergence Of Life ◽  
Long Chain ◽  
Chain Hydrocarbon

Abiotic CO2 reduction on transition metal minerals has been proposed to account for the synthesis of organic compounds in alkaline hydrothermal systems, but this reaction lacks experimental support, as only short-chain hydrocarbons (<C5) have been synthesized in artificial simulation. This presents a question: What particular hydrothermal conditions favor long-chain hydrocarbon synthesis? Here, we demonstrate the hydrothermal bicarbonate reduction at ∼300 °C and 30 MPa into long-chain hydrocarbons using iron (Fe) and cobalt (Co) metals as catalysts. We found the Co0 promoter responsible for synthesizing long-chain hydrocarbons to be extraordinarily stable when coupled with Fe−OH formation. Under these hydrothermal conditions, the traditional water-induced deactivation of Co is inhibited by bicarbonate-assisted CoOx reduction, leading to honeycomb-native Co nanosheets generated in situ as a new motif. The Fe−OH formation, confirmed by operando infrared spectroscopy, enhances CO adsorption on Co, thereby favoring further reduction to long-chain hydrocarbons (up to C24). These results not only advance theories for an abiogenic origin for some petroleum accumulations and the hydrothermal hypothesis of the emergence of life but also introduce an approach for synthesizing long-chain hydrocarbons by nonnoble metal catalysts for artificial CO2 utilization.

Mineral–microbe interactions in deep-sea hydrothermal systems: a challenge for Raman spectroscopy

2010 ◽  
Vol 368 (1922) ◽  
pp. 3067-3086 ◽  
Author(s):  
J. A. Breier ◽  
S. N. White ◽  
C. R. German
Keyword(s):  
Raman Spectroscopy ◽  
Deep Sea ◽  
Low Cost ◽  
Hydrothermal Systems ◽  
Laser Raman Spectroscopy ◽  
Full Potential ◽  
Laser Raman ◽  
Mineral Phases ◽  
Hydrothermal Environments

In deep-sea hydrothermal environments, steep chemical and thermal gradients, rapid and turbulent mixing and biologic processes produce a multitude of diverse mineral phases and foster the growth of a variety of chemosynthetic micro-organisms. Many of these microbial species are associated with specific mineral phases, and the interaction of mineral and microbial processes are of only recently recognized importance in several areas of hydrothermal research. Many submarine hydrothermal mineral phases form during kinetically limited reactions and are either metastable or are only thermodynamically stable under in situ conditions. Laser Raman spectroscopy is well suited to mineral speciation measurements in the deep sea in many ways, and sea-going Raman systems have been built and used to make a variety of in situ measurements. However, the full potential of this technique for hydrothermal science has yet to be realized. In this focused review, we summarize both the need for in situ mineral speciation measurements in hydrothermal research and the development of sea-going Raman systems to date; we describe the rationale for further development of a small, low-cost sea-going Raman system optimized for mineral identification that incorporates a fluorescence-minimizing design; and we present three experimental applications that such a tool would enable.

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