We studied the exchange of chemical elements by diffusion between magmas of tephritic and phonolitic composition from the Canary Islands, performing experiments at high pressure and high temperature with different amounts of added water. Our results characterize the way water and temperature affect the diffusion process, and we also find unexpectedly high mobility of aluminium, which may be related to its variable chemical bonding in highly alkaline melts. 

Mechanical interaction between quartz inclusions in garnet creates residual pressure in the inclusion used to calculate the pressure and temperature where the two minerals formed. We crystallised quartz and garnet at high pressure and temperature and then adjusted the experimental pressure to observe the interaction between the quartz inclusions and garnet host. The quartz and garnet adjust to the new experimental pressures, reset inclusion pressures, and no longer match entrapment conditions.

To explore the influence of the redox state of the environment on the serpentinization reaction, we have developed an original experimental setup. Reducing conditions, leading to the formation of serpentine and magnetite, and oxidizing conditions, leading to the formation of serpentine and hematite, are discussed in terms of analogues of low- and high-permeability hydrothermal systems, respectively. The influence of the redox on brucite stability and hydrogen production is also established.

Inclusions in natural rocks are an invaluable asset for geoscientists because they provide information about processes in the Earth's history that are otherwise hidden or subsequently overprinted. In this paper we review the development over the last 200 years of the concepts and methods to measure the remnant pressures in mineral inclusions and how they can be used to determine pressures and temperatures at which the inclusions were formed deep within the Earth.

Li is a critical element that is often enriched in pegmatites. To better understand the enrichment of Li in such systems, it is necessary to understand the underlying transport mechanisms. We performed experiments to investigate diffusion rates and exchange mechanisms of Li between a Li-rich and a Li-poor melt at high temperature and pressure. Our results indicate that fluxing elements do not increase the diffusivity of Li compared to a flux-free melt.

This study presents a new method designed to analyze micrometer-scale chemical and isotopic profiles in minerals, glasses, and other solids. The employed technique combines plasma mass spectrometers and a state-of-the-art femtosecond laser equipped with open-source software (LinuxCNC) that controls the movement of the laser beam. It allows for equably drilling into the sample surface, e.g., in order to measure chemically or isotopically zoned or heterogeneous materials at micrometer scales.

We calibrate new models for the properties of solid and liquid FePt alloy. FePt alloy is used in experiments investigating the origin, differentiation, and evolution of planets to characterize oxygen fugacity. The new models facilitate use of FePt for more extreme conditions than has been possible previously. We also describe shortcomings in the present knowledge of FePt alloy properties and highlight strategies that could improve such knowledge.

We have developed the thermodynamic theory of the properties of inclusions consisting of more than one phase, including inclusions containing solids plus a fluid. We present a software utility that enables for the first time the entrapment conditions of multiphase inclusions to be determined from the measurement of their internal pressure when that is measured in a laboratory.

In this work we have applied the elastic geobarometry approach to a Chinese diamond in order to determine the depth of formation of an olivine-bearing diamond. Together with the temperature of residence at which the diamond resided in the mantle, we were able to discover that the diamond was formed at about 190 km depth. Beyond the geological meaning of our results, this work could be a reference paper for future works on Chinese diamonds using elastic geobarometry.

This work presents an in-depth description of a new design for a high-temperature gas-mixing furnace using a mixture of CO–CO₂–SO₂. It has been designed and built with user safety in mind. The furnace can sustain temperatures of up to 1650 °C. This furnace sets itself apart with its size and unique quench mechanism. Crucially, the apparatus has the ability to change the gas mixture during an experiment. This feature allows the user to simulate natural environments, such as volcanoes.

Volatile diffusivities in silicate melts control the nucleation and growth of bubbles in ascending magma. We investigated the diffusion of CO₂ in an anhydrous and hydrous leucititic melt at high temperatures and high pressure. CO₂ diffusion profiles were measured via attenuated total reflection Fourier transform infrared spectroscopy. CO₂ diffusion increases with increasing temperature and water content. The data can be used to understand the CO₂ degassing behaviour of leucititic melts.

Carbonates reduce the melting point of the mantle, and carbonate melts produced in low-degree melting of a carbonated mantle are considered the precursor of CO₂-rich magmas. We established experimentally the melting relations of carbonates up to 9 GPa, showing that Mg-carbonates melt incongruently to periclase and carbonate melt. The trace element signature of carbonate melts parental to kimberlites is approached by melting of Mg-rich carbonates.

Magmas transport large amounts of CO₂ from Earth's mantle into the atmosphere and thus contribute significantly to the global carbon cycle. We have developed an experimental method to homogenize at high pressure small liquid droplets trapped in magmatic crystals to gain access to the initial composition of the parental magma (major and volatile elements). With this technique, we show that magmas produced by melting of the subcontinental mantle contain several weight percent of CO₂.

This review provides an overview of ex situ carbon-saturated COH fluid experiments at upper-mantle conditions. Several authors experimentally investigated the effect of COH fluids. However, fluid composition is rarely tackled as a quantitative issue, and rather infrequently fluids are analyzed as the associated solid phases in the experimental assemblage. Recently, improved techniques have been proposed for analyses of COH fluids, leading to significant advancement in fluid characterization.

Amphibole–liquid partitioning of elements of geological relevance is experimentally derived at conditions compatible with those of the Earth's upper mantle. Experiments are carried out at different oxygen fugacity conditions and variable Cl content in order to investigate their influence on the amphibole–liquid partition coefficients. Our results point to the capability of amphibole to act as filter for trace elements at upper-mantle conditions, oxidized conditions, and Cl-rich environments.

Detailed knowledge of the mechanisms ruling water incorporation in amphibole is essential to understand how much water can be fixed at upper-mantle conditions by this mineral. We provide the experimental evidence of the Cl effect on the oxo-substitution and the incorporation of water in amphibole. Finally, we highlight the versatility of confocal micro-Raman spectroscopy as an analytical tool to quantify water in amphibole.

How, and how fast, does hydrogen move through crystals? We consider this question by adding hydrogen, by diffusion, to synthetic crystals of olivine doped with trace amounts of chromium. Even in a highly simplified system, the behaviour of hydrogen is complex. Hydrogen can move into and through the crystal using various pathways (different defects within the crystal) and hop between these pathways too.

Grain boundary diffusion is orders of magnitude faster compared to volume diffusion. We studied this fast transport process in a well-defined garnet grain boundary. State-of-the-art microscopy was used for quantification. A dedicated numerical diffusion model shows that iron diffusion requires the operation of two diffusion modes, one fast, one slow. We conclude that impurity bulk diffusion in garnet aggregates is always dominated by grain boundary diffusion.

We experimentally explored direct entrapment of breyite (CaSiO₃) by diamond at upper-mantle conditions in a model subducted sediment rather than formation by retrogression of CaSiO₃ perovskite, implying a deeper origin. Anhydrous low-T melting of CaCO₃+SiO₂ precludes breyite formation. Under hydrous conditions, reduction of melt results in graphite with breyite. Thus, breyite inclusions in natural diamond may form from aragonite + coesite or carbonate melt at 6–8 GPa via reduction with water.