This work was supported by the Natural Sciences and Engineering Research Council of Canada Equipment, Discovery and Discovery Accelerator Grants awarded to J.M.B. N.R.B acknowledges support from the Carnegie Institution of Washington post-doctoral fellowship program. Stephen Elardo is also thanked for his assistance prior to filming with the piston-cylinder press at the Geophysical Lab.

The Authors have nothing to disclose.

The results of inclusion-free experiments performed using the protocols outlined here have previously been compared with literature data in references29 (Os, Ir, Au), 30 (Re, Au) and 31 (Pt). Pt is most instructive in demonstrating the usefulness of inclusion-free run-products. For experiments run at low fO2, Ertel et al.48 assigned inclusions to a stable origin and therefore restricted data reduction to the lowest counts-per-second region of time-r...

Terrestrial accretion is thought to have occurred as a series of collisions between planetesimals with a chondritic bulk composition, terminating in a giant-impact phase thought responsible for moon formation1,2. Heating of the proto-earth by impacts and the decay of short-lived isotopes was sufficient to cause extensive melting and the formation of a magma ocean or ponds through which dense Fe-rich metallic melts could descend. Upon reaching the base of the magma ocean, metallic melts encounter a rheological boundary, stall, and undergo final metal-silicate equilibrium before eventually descending through the solid mantle to the growing core2. Further chemical communication between metal and silicate phases as metallic melt traverses the solid portion of the mantle is thought to be precluded due to the large size and rapid descent of metal diapirs3. This primary differentiation of the Earth into a metallic core and silicate mantle is revealed today by both geophysical and geochemical observations4&#8211;6. Interpreting these observations to yield plausible conditions for metal-silicate equilibrium at the base of a magma ocean, however, requires an appropriate database of experimental results.
The primitive upper mantle (PUM) is a hypothetical reservoir comprising the silicate residue of core formation and its composition therefore reflects the behaviour of trace elements during metal-silicate equilibrium. Trace elements are distributed between metal and silicate melts during core segregation on the basis of their geochemical affinity. The magnitude of an elements preference for the metal phase can be described by the metal-silicate partition coefficient <img alt="Equation 1" src="/files/ftp_upload/52725/52725eq1.jpg" />
<img alt="Equation 2" src="/files/ftp_upload/52725/52725eq2.jpg" />&#160; &#160; &#160; &#160; &#160;(1)
Where <img alt="Equation 3" src="/files/ftp_upload/52725/52725eq3.jpg" /> and <img alt="Equation 4" src="/files/ftp_upload/52725/52725eq4.jpg" /> denote the concentration of element i in metal and silicate melt respectively. Values of <img alt="Equation 5" src="/files/ftp_upload/52725/52725eq5.jpg" /> &#62;1 indicate siderophile (iron-loving) behaviour and those &#60;1 lithophile (rock-loving) behavior. Estimates of the PUM composition show that siderophile elements are depleted relative to chondrites7, typically considered as representative of Earth&#8217;s bulk composition6,8. This depletion is due to sequestration of siderophile elements by the core, and for refractory elements its magnitude should directly reflect values of <img alt="Equation 5" src="/files/ftp_upload/52725/52725eq5.jpg" /> . Lab experiments therefore seek to determine values of <img alt="Equation 5" src="/files/ftp_upload/52725/52725eq5.jpg" /> over a range of pressure (P), temperature (T) and oxygen fugacity (fO2) conditions that are relevant to metal segregation from the base of a magma ocean. The results of these experiments may then be used to delineate regions of P-T-fO2 space that are compatible with the PUM abundance of multiple siderophile elements (e.g.,9&#8211;11).
The high pressures and temperatures relevant to a magma ocean scenario can be recreated in the laboratory using either a piston-cylinder or multi-anvil press. The piston-cylinder apparatus provides access to moderate pressure (~2 GPa) and high temperature (~2,573 K) conditions, but enables large sample volumes and a variety of capsule materials to be easily used. The rapid cooling rate also permits quenching of a range of silicate melt compositions to a glass, thus simplifying textural interpretation of the run-products. The multi-anvil apparatus typically employs smaller sample volumes but with suitable assembly designs can achieve pressures up to ~27 GPa and temperatures of ~3,000 K. The use of these methods has allowed partitioning data for many of the moderately and slightly siderophile elements to be gathered over a large range of P-T conditions. Predictions of the PUM composition based on these data suggest metal-silicate equilibrium occurred at average pressure and temperature conditions in excess of ~29 GPa and 3,000 K respectively, although the exact values are model dependent. In order to account for the PUM abundance of certain redox sensitive elements (e.g.,&#160;V, Cr) the fO2 is also thought to evolve during accretion from ~4 to 2 log units below that imposed by co-existing iron and w&#252;stite (FeO) at equivalent P-T conditions (the iron-w&#252;stite buffer)12.
Although the PUM abundance of many siderophile elements can be accounted for by metal-silicate equilibrium at the base of a deep magma ocean, it has proved difficult to assess if this situation also applies to the most highly siderophile elements (HSEs). The extreme affinity of the HSEs for iron-metal indicated by low pressure (P ~0.1 MPa) and temperature (T &#60;1,673 K) experiments suggests the silicate earth should be strongly depleted in these elements. Estimates of the HSE content for PUM, however, indicate only a moderate depletion relative to chondrite (Figure 1). A commonly posited solution to the apparent HSE excess is that Earth experienced a late-accretion of chondritic material subsequent to core-formation13. This late-accreted material would have mixed with the PUM and elevated HSE concentrations but had a negligible effect on more abundant elements. Alternatively, it has been suggested that the extremely siderophile nature of HSEs indicated by low P-T experiments does not persist to the high P-T conditions present during core-formation14,15. In order to test these hypotheses, experiments must be carried out to determine the solubility and metal-silicate partitioning of HSEs at appropriate conditions. Contamination of the silicate portion of quenched run-products in many previous studies however, has complicated run-product analysis and obscured the true partition coefficients for HSEs between metal and silicate melts.
In partitioning experiments where the HSEs are present at concentration levels appropriate to nature, the extreme preference of these elements for Fe-metal prevents their measurement in the silicate melt. To circumvent this problem, solubility measurements are made in which the silicate melt is saturated in the HSE of interest and values of <img alt="Equation 5" src="/files/ftp_upload/52725/52725eq5.jpg" /> are calculated using the formalism of Borisov et al.16. Quenched silicate run-products from HSE solubility experiments performed at reducing conditions, however, often display evidence for contamination by dispersed HSE&#177;Fe inclusions17. Despite the near ubiquity of these inclusions in low fO2 experiments containing Pt, Ir, Os, Re and Ru, (e.g., 18&#8211;27), there is notable variability between studies in their textural presentation; compare for example references 22 and 26. Although it has been demonstrated that inclusions can form which are a stable phase at the run conditions of an experiment28, this does not preclude the formation of inclusions as the sample is quenched. Uncertainty surrounding the origin of inclusions makes the treatment of analytical results difficult, and has led to ambiguity over the true solubility of HSEs in reduced silicate melts. Inclusion-free run-products are required to assess which studies have adopted an analytical approach that yields accurate dissolved HSE concentrations. Considerable progress in suppressing the formation of metal-inclusions at reducing conditions has now been demonstrated in experiments using a piston-cylinder apparatus, in which the sample design was amended from previous studies by adding either Au or Si to the starting materials29&#8211;31. The addition of Au or elemental Si to the starting materials alters the sample geometry or fO2 evolution of the experiment respectively. These methods are intended to suppress metal inclusion formation by altering the timing of HSE in-diffusion versus sample reduction, and are discussed in Bennett et al.31. Unlike some previous attempts to cleanse the silicate melt of inclusions, such as mechanically assisted equilibration and the centrifuging piston-cylinder, the present protocol can be implemented without specialized apparatus and is suitable for high P-T experiments.
Described in detail here is a piston-cylinder based approach to determine the solubility of Re, Os, Ir, Ru, Pt and Au in silicate melt at high temperature (&#62;1,873 K), 2 GPa and an fO2 similar to that of the iron-w&#252;stite buffer. Application of a similar experimental design may also prove successful in HSE experiments at other pressures, providing the required phase relations, wetting properties and kinetic relationships persist to the chosen conditions. Existing data however, are insufficient to predict whether our sample design will be successful at pressures corresponding to a deep magma ocean. Also outlined is a general approach used to determine moderately and slightly siderophile element (MSE and SSE respectively) partitioning using a multi-anvil device. Extension of the inclusion-free dataset for HSEs to high pressure is likely to employ similar multi-anvil methods. Together, these procedures provide a means to constrain both the conditions of core-segregation and the stages of terrestrial accretion.

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metal-silicate partitioning at high pressure and temperature: experimental methods and a protocol to suppress highly siderophile element inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

The following examples and discussion focus on experiments to determine HSE solubility in silicate melts at low fO2. For comprehensive examples of how MSE and SSE partitioning data from multi-anvil experiments may be used to constrain the P-T-fO2 conditions of core metal segregation, the reader is referred to references9&#8211;11. Figure 7B-D&#160;displays back scattered electron images from typical experimental ru...

Watch this Scientific Journal Video about Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions at JoVE.co

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

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12.4K Views.  University of Toronto. We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

Video: Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40&#160;&#176;C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure.
The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)1-4. For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion.

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus is a unique tool to study, without sampling, phase behavior under a wide range of pressures. Using a cathetometer, very precise volume measurements can be recorded to measure liquid expansion and phase composition. Thus, this synthetic method enables the study of (1) phase equilibria of multi-component mixtures and (2) the partition behavior of catalyst or model compounds as a function of pressure.

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. ...

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

Engineering

Simulation of the Planetary Interior Differentiation Processes in the Laboratory

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to that layered structure, (1) percolation of liquid metal in a solid silicate matrix by planet differentiation, and (2) inner core crystallization by subsequent planet cooling. We conduct high-pressure and high-temperature experiments to simulate both processes in the laboratory. Formation of percolative planetary core depends on the efficiency of melt percolation, which is controlled by the dihedral (wetting) angle. The percolation simulation includes heating the sample at high pressure to a target temperature at which iron-sulfur alloy is molten while the silicate remains solid, and then determining the true dihedral angle to evaluate the style of liquid migration in a crystalline matrix by 3D visualization. The 3D volume rendering is achieved by slicing the recovered sample with a focused ion beam (FIB) and taking SEM image of each slice with a FIB/SEM crossbeam instrument. The second set of experiments is designed to understand the inner core crystallization and element distribution between the liquid outer core and solid inner core by determining the melting temperature and element partitioning at high pressure. The melting experiments are conducted in the multi-anvil apparatus up to 27 GPa and extended to higher pressure in the diamond-anvil cell with laser-heating. We have developed techniques to recover small heated samples by precision FIB milling and obtain high-resolution images of the laser-heated spot that show melting texture at high pressure. By analyzing the chemical compositions of the coexisting liquid and solid phases, we precisely determine the liquidus curve, providing necessary data to understand the inner core crystallization process.

The high-pressure and high-temperature experiments described here mimic planet interior differentiation processes. The processes are visualized and better understood by high-resolution 3D imaging and quantitative chemical analysis.

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to ...

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature (&#62; 300 &#176;C). However, because of the low stress resolution of current solid-pressure-medium apparatuses, high-resolution measurements are today restricted to low-pressure deformation experiments in the gas-pressure-medium apparatus. A new generation of solid-medium piston-cylinder (&#34;Griggs-type&#34;) apparatus is here described. Able to perform high-pressure deformation experiments up to 5 GPa and designed to adapt an internal load cell, such a new apparatus offers the potential to establish a technological basis for high-pressure rheology. This paper provides video-based detailed documentation of the procedure (using the &#34;conventional&#34; solid-salt assembly) to perform high-pressure, high-temperature experiments with the newly designed Griggs-type apparatus. A representative result of a Carrara marble sample deformed at 700 &#176;C, 1.5 GPa and 10-5 s-1 with the new press is also given. The related stress-time curve illustrates all steps of a Griggs-type experiment, from increasing pressure and temperature to sample quenching when deformation is stopped. Together with future developments, the critical steps and limitations of the Griggs apparatus are then discussed.

Rock deformation needs to be quantified at high pressure. A description of the procedure to perform deformation experiments in a newly designed solid-medium Griggs-type apparatus is here given. This provides technological basis for future rheological studies at pressures up to 5 GPa.

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature ...

Environment

Stress Distribution During Cold Compression of Rocks and Mineral Aggregates Using Synchrotron-based X-Ray Diffraction

We report detailed procedures for performing compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus (D-DIA) coupled with synchrotron X-radiation. A cube-shaped sample assembly is prepared and compressed, at room temperature, by a set of four X-ray transparent sintered diamond anvils and two tungsten carbide anvils, in the lateral and the vertical planes, respectively. All six anvils are housed within a 250-ton hydraulic press and driven inward simultaneously by two wedged guide blocks. A horizontal energy dispersive X-ray beam is projected through and diffracted by the sample assembly. The beam is commonly in the mode of either white or monochromatic X-ray. In the case of white X-ray, the diffracted X-rays are detected by a solid-state detector array that collects the resulting energy dispersive diffraction pattern. In the case of monochromatic X-ray, the diffracted pattern is recorded using a two-dimensional (2-D) detector, such as an imaging plate or a charge-coupled device (CCD) detector. The 2-D diffraction patterns are analyzed to derive lattice spacings. The elastic strains of the sample are derived from the atomic lattice spacing within grains. The stress is then calculated using the predetermined elastic modulus and the elastic strain. Furthermore, the stress distribution in two-dimensions allow for understanding how stress is distributed in different orientations. In addition, a scintillator in the X-ray path yields a visible light image of the sample environment, which allows for the precise measurement of sample length changes during the experiment, yielding a direct measurement of volume strain on the sample. This type of experiment can quantify the stress distribution within geomaterials, which can ultimately shed light on the mechanism responsible for compaction. Such knowledge has the potential to significantly improve our understanding of key processes in rock mechanics, geotechnical engineering, mineral physics, and material science applications where compactive processes are important.

We report detailed procedures for compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus coupled with synchrotron X-radiation. Such experiments allow quantification of the stress distribution within samples, that ultimately sheds light on compaction processes in geomaterials.

We report detailed procedures for performing compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus (D-DIA) ...

High Pressure Single Crystal Diffraction at PX^2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline at the Advanced Photon Source. The DAC program at 13-BM-C is part of the Partnership for Extreme Xtallography (PX^2) project. BX-90 type DACs with conical-type diamond anvils and backing plates are recommended for these experiments. The sample chamber should be loaded with noble gas to maintain a hydrostatic pressure environment. The sample is aligned to the rotation center of the diffraction goniometer. The MARCCD area detector is calibrated with a powder diffraction pattern from LaB6. The sample diffraction peaks are analyzed with the ATREX software program, and are then indexed with the RSV software program. RSV is used to refine the UB matrix of the single crystal, and with this information and the peak prediction function, more diffraction peaks can be located. Representative single crystal diffraction data from an omphacite (Ca0.51Na0.48)(Mg0.44Al0.44Fe2+0.14Fe3+0.02)Si2O6 sample were collected. Analysis of the data gave a monoclinic lattice with P2/n space group at 0.35 GPa, and the lattice parameters were found to be: a = 9.496 &#177;0.006 &#197;, b = 8.761 &#177;0.004 &#197;, c = 5.248 &#177;0.001 &#197;, &#946; = 105.06 &#177;0.03&#186;, &#945; = &#947; = 90&#186;.

In this report, we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell at the GSECARS 13-BM-C beamline at the Advanced Photon Source. ATREX and RSV programs are used to analyze the data.

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the ...

An Experimental Protocol for Studying Mineral Effects on Organic Hydrothermal Transformations

Organic-mineral interactions are widely occurring in hydrothermal environments, such as hot springs, geysers on land, and the hydrothermal vents in the deep ocean. Roles of minerals are critical in many hydrothermal organic geochemical processes. Traditional hydrothermal methodology, which includes using reactors made of gold, titanium, platinum, or stainless-steel, is usually associated with the high cost or undesired metal catalytic effects. Recently, there is a growing tendency for using the cost-effective and inert quartz or fused silica glass tubes in hydrothermal experiments. Here, we provide a protocol for carrying out organic-mineral hydrothermal experiments in silica tubes, and we describe the essential steps in the sample preparation, experimental setup, products separation, and quantitative analysis. We also demonstrate an experiment using a model organic compound, nitrobenzene, to show the effect of an iron-containing mineral, magnetite, on its degradation under a specific hydrothermal condition. This technique can be applied to study complex organic-mineral hydrothermal interactions in a relatively simple laboratory system.

Earth-abundant minerals play important roles in the natural hydrothermal systems. Here, we describe a reliable and cost-effective method for the experimental investigation of organic-mineral interactions under hydrothermal conditions.

Organic-mineral interactions are widely occurring in hydrothermal environments, such as hot springs, geysers on land, and the hydrothermal vents in the ...

Using Flexible Gold-Titanium Reaction Cells to Simulate Pressure-Dependent Microbial Activity in the Context of Subsurface Biomining

Laboratory studies investigating subsurface microbial processes, such as metal leaching in deep ore deposits (biomining), share common and challenging obstacles, including the special environmental conditions that need to be replicated, e.g., high pressure and in some cases acidic solutions. The former requires an experimental setup suitable for pressurization up to 100 bar, while the latter demands a fluid container with high chemical resistance against corrosion and unwanted chemical reactions with the container wall. To meet these conditions for an application in the field of in situ biomining, a special flexible gold-titanium reaction cell inside a rocking high-pressure reactor was used in this study. The described system allowed simulation of in situ biomining through sulfur-driven microbial iron reduction in an anoxic, pressure-controlled, highly chemically inert experimental environment. The flexible gold-titanium reaction cell can accommodate up to 100 mL of sample solution, which can be sampled at any given time point while the system maintains the desired pressure. Experiments can be performed on timescales ranging from hours to months. Assembling the high-pressure reactor system is fairly time consuming. Nevertheless, when complex and challenging (microbiological) processes occurring in the earth&#39;s deep subsurface in chemically aggressive fluids have to be investigated in the laboratory, the advantages of this system outweigh the disadvantages. The results found that even at high pressure the microbial consortium is active, but at significantly lower metabolic rates.

This protocol describes microbial experiments under elevated pressures to study in situ biomining processes. The experimental approach employs a rocking high-pressure reactor equipped with a gold-titanium reaction cell containing a microbial culture in an acidic, iron-rich medium.

Laboratory studies investigating subsurface microbial processes, such as metal leaching in deep ore deposits (biomining), share common and challenging ...

Analyzing Melts and Fluids from Ab Initio Molecular Dynamics Simulations with the UMD Package

We have developed a Python-based open-source package to analyze the results stemming from ab initio molecular-dynamics simulations of fluids. The package is best suited for applications on natural systems, like silicate and oxide melts, water-based fluids, and various supercritical fluids. The package is a collection of Python scripts that include two major libraries dealing with file formats and with crystallography. All the scripts are run at the command line. We propose a simplified format to store the atomic trajectories and relevant thermodynamic information of the simulations, which is saved in UMD files, standing for Universal Molecular Dynamics. The UMD package allows the computation of a series of structural, transport and thermodynamic properties. Starting with the pair-distribution function it defines bond lengths, builds an interatomic connectivity matrix, and eventually determines the chemical speciation. Determining the lifetime of the chemical species allows running a full statistical analysis. Then dedicated scripts compute the mean-square displacements for the atoms as well as for the chemical species. The implemented self-correlation analysis of the atomic velocities yields the diffusion coefficients and the vibrational spectrum. The same analysis applied on the stresses yields the viscosity. The package is available via the GitHub website and via its own dedicated page of the ERC IMPACT project as open-access package.

Melts and fluids are ubiquitous vectors of mass transport in natural systems. We have developed an open-source package to analyze ab initio molecular-dynamics simulations of such systems. We compute structural (bonding, clusterization, chemical speciation), transport (diffusion, viscosity) and thermodynamic properties (vibrational spectrum).

We have developed a Python-based open-source package to analyze the results stemming from ab initio molecular-dynamics simulations of fluids. The package ...