Matteo Alvaro

• PhD
• Professor (Full) at University of Pavia

Metamorphic rocks are the records of plate tectonic processes whose reconstruction relies on correct estimates of the pressures and temperatures (P-T) experienced by these rocks through time. Unlike chemical geothermobarometry, elastic geobarometry does not rely on chemical equilibrium between minerals, so it has the potential to provide informatio...

The mechanisms attending the burial of crustal material and its exhumation before and during the Alpine orogeny are controversial. New mechanical models propose local pressure perturbations deviating from lithostatic pressure as a possible mechanism for creating (ultra-)high-pressure rocks in the Alps. These models challenge the assumption that met...

The mineralogy and chemical compositions of inclusions in diamonds are the primary source of information about the environment in which diamonds grow and help constrain the mechanisms of their growth. However, the vast majority of the information about inclusions has been gathered by extracting them from their diamonds, thus destroying all possibil...

All available volume and elasticity data for the garnet end-members grossular, pyrope, almandine and spessartine have been re-evaluated for both internal consistency and for consistency with experimentally measured heat capacities. The consistent data were then used to determine the parameters of third-order Birch–Murnaghan EoS to describe the isot...

At the pressure and temperature conditions of the lower crust, quartz undergoes a displacive phase transition from a trigonal (α) to a hexagonal phase (β). At room pressure, the α–β quartz transition occurs at 574.1 °C and it is associated with large changes in the thermodynamic and elastic properties. For that reason, it is interpreted as the caus...

Iron meteorites, originating from the deepest parts of their parent bodies and separated during major break‐up events, surprisingly rarely contain diamonds despite experiencing similar pressure–temperature conditions as diamond‐bearing ureilites. In this study, graphite from three non‐magmatic IAB iron meteorites Canyon Diablo, Campo del Cielo, and...

RamanCrystalHunter (RCH) is a new software program designed to pre-process, analyze, and identify Raman spectra by comparison with spectra in the RamanCrystalHunter Database (RCHDB). The software is free and can be downloaded from the website https://www.fabrizionestola.com/rch. RCH is characterized by a simple graphical user interface, making it s...

Extraterrestrial carbon gives insights into the origin of life and processes that took place billions of years ago in our solar system. Here, the authors provide an overview of what is known and of unanswered questions with a meteoritical focus.

Solid inclusion piezobarometry is the determination of the entrapment conditions of solid inclusions in a host by measurement and interpretation of the residual pressure of the inclusion. The development over the past two centuries of the concepts, analytical tools and measurement techniques of inclusion piezobarometry is reviewed, and potential fu...

Due to their widespread occurrence in several geological settings, omphacite inclusions could be used for elastic Raman geothermobarometry. However, the Raman scattering of complex silicate minerals entrapped in a host depends on both the chemical composition and elastic strain developed during the metamorphic pathway, which makes the task very cha...

The healthcare sector has always paid attention to social and economic sustainability. Still, healthcare is a relevant industry with a high environmental impact. There is a call to include and consider environmental sustainability as a guiding principle for the healthcare sector of tomorrow. The United Kingdom, through its NHS and Royal Colleges, h...

Quartz crystals with zircon inclusions were synthesized using a piston-cylinder apparatus to experimentally evaluate the use of inclusions in “soft” host minerals for elastic thermobarometry. Synthesized zircon inclusion strains and, therefore, pressures (Pinc) were measured using Raman spectroscopy and then compared with the expected inclusion str...

Il settore sanitario è da sempre attento alle dinamiche legate alle sostenibilità sociale ed economica. Tuttavia, la sanità rappresenta un'industria che, date le proprie caratteristiche (un numero elevato di addetti e di strutture, pratiche manageriali complesse, largo impiego di beni sia consumabili che di investimento), produce un importante impa...

The subduction-exhumation history of the Grapesvare nappe in the northern Seve Nappe Complex (Scandinavian Caledonides) is recorded as late Cambrian/Early Ordovician ultra-high pressure (UHP) and subsequent amphibolite facies metamorphic events. Records of these events obscured earlier metamorphic episodes that are important for understanding the t...

The aim of this study was to evaluate the potential of Aspergillus tubingensis in extracting metals from rocks simulating Martian regolith through biomining. The results indicated that the fungal strain produced organic acids, particularly oxalic acid, in the first five days, leading to a rapid reduction in the pH of the culture medium. This acidic...

In the absence of Mercurian rocks or meteorites in our collections, komatiites and boninites are often proposed as the best analogue rocks to Mercury lavas. However, despite previous work on the possible analogy between komatiites and Mercury rocks, similar work has not been done for boninites. In this work, we investigate the whole-rock geochemist...

Elastic thermobarometry (or piezobarometry) is the process of determining the P (pressure) and T (temperature) of entrapment of inclusions from their pressure, stress or strain measured when their host mineral is at room conditions. The methods and software used for piezobarometry are currently restricted to inclusions consisting of single phases....

Quartz is one of the most abundant minerals in the Earth crust and therefore quartz inclusions in garnet are of great interest for elastic geobarometry, an approach that exploits the elastic properties of the mineral pair to back-calculate the conditions of inclusion entrapment. However, the high-temperature behavior of quartz inclusions close to t...

Elastic geothermobarometry relies on the contrast between the thermal expansion and compressibility of a mineral inclusion and its surrounding host, leading to a residual pressure in the inclusion (Pinc) that may differ significantly from the external pressure. Quartz-in-garnet (QuiG) inclusion-host systems are widely used in elastic geothermobarom...

Volcanic arcs above subduction zones are thought to be the principal locations where juvenile magmatic crust forms and is refined to become continental crust with an andesitic composition. During this refinement mechanism, the formation of dense garnet pyroxenites (arclogites), represented by high-pressure cumulates and restites after partial melti...

Al Huwaysah 010 is an ungrouped achondrite meteorite, recently referred to as a brachinite‐like meteorite. This meteorite, showing a fine‐grained assemblage of low‐Ca pyroxene and opaque phases, is strongly reduced in comparison to other reduced brachinites. The occurrence of some tiny plates of graphite and oldhamite in this meteorite suggests tha...

Ureilites meteorite fragments present different levels of shock classified on the basis of optical observations of shock features in silicates. We have investigated by scanning electron microscopy (SEM), micro X-Ray Diffraction (XRD) and Micro-Raman Spectroscopy (MRS) five ureilitic fragments (FRO 95028, FRO 01089, FRO 97013, FRO 01088 and FRO 0101...

Fluid and mineral inclusions in metamorphic rocks allow the understanding of fluid-involved processes in subduction-zones providing essential contributions to the nature of geochemical processes and element cycling in present day subduction zones. In this work, we studied ultramafic granulite from the high-pressure (HP) and high-temperature (HT) me...

Upon exhumation and cooling, contrasting compressibilities and thermal expansivities induce differential strains (volume mismatches) between a host crystal and its inclusions. These strains can be quantified in situ using Raman spectroscopy or X-ray diffraction. Knowing equations of state and elastic properties of minerals, elastic thermobarometry...

The liquid viscosity of multiphase systems is usually retrieved by the use of combined chemical analysis and empirical chemistry-based models. Here we present an alternative approach to study the glassy pools in highly crystallized basaltic-andesite and trachybasalt samples obtained from isothermal crystallization experiment at different shear rate...

Spinel is potentially one of the best minerals for elastic geobarometry, but the large uncertainties in the published equation of state (EoS) of spinel prevent the application of elastic geobarometry using spinel. We have determined the EoS of MgAl2O4 from literature data on the volume, elasticity, and isobaric heat capacity by paying particular at...

Elastic thermobarometry of host-inclusion systems for back-calculating pressure (P) and temperature (T) conditions of inclusion entrapment relies on the assumption that the host-inclusion rheology is purely elastic. In this study, we have explored both the elastic and nonelastic behavior of zircon-in-garnet (ZiG) systems by in situ Raman spectrosco...

The Seve Nappe Complex is a subduction related high-grade metamorphic unit that was emplaced onto the margin of Baltica during Caledonian orogenesis. In this paper, the tectono-metamorphic evolution of the Lower Seve Nappe in the Scandinavian Caledonides was characterized with the help of the continuous COSC-1 drill core, using a combination of var...

The internal structure and dynamics of Earth have been shaped by the 660 km boundary between the mantle transition zone and lower mantle. However, due to the paucity of natural samples from this depth, the nature of this boundary—its composition and volatile fluxes across it—remain debated. Here we analyse the mineral inclusions in a rare type IaB...

The first occurrence of ultra-high-pressure (UHP) metamorphism in the Western Alps was documented by Chopin in 1984 (Chopin, 1984) with the discovery of coesite in the southern Dora Maira massif. Since then, just one additional UHP terrain was discovered until the end of the 90's. In recent times, new occurrences of coesite have been reported in di...

Mercurian meteorites have never been found on Earth. However, thanks to the NASA’s MESSENGER mission, some constraints on the geochemistry and mineralogy of Mercurian rocks are now available. Results from the X- and Gamma-ray Spectrometers onboard the MESSENGER mission suggest a surface composition with Mg/Si ratio within 0.33-0.67 and a Fe/Si rati...

The trace‐element composition of rutile is commonly used to constrain P‐T‐t‐conditions for a wide range of metamorphic systems. However, recent studies have demonstrated the redistribution of trace elements in rutile via high‐diffusivity pathways and dislocation‐impurity associations related to the formation and evolution of microstructures. Here w...

Natural diamonds and their inclusions provide unique glimpses of mantle processes from as deep as ~800 km and dating back to 3.5 G.y. Once formed, diamonds are commonly interpreted to travel upward, either slowly within mantle upwellings or rapidly within explosive, carbonate-rich magmas erupting at the surface. Although global tectonics induce sub...

Here we studied metapelites from the ultrahigh-pressure (UHP) Brossasco-Isasca unit in the Dora-Maira Massif, Western Alps, combining zircon-in-garnet elastic geo-thermobarometry and phase equilibria modelling. We determined the residual strain and pressure of zircon inclusions via micro-Raman spectroscopy and the dedicated softwares available onli...

Raman elastic geobarometry for mineral host-inclusion systems is used to determine the strains acting on an inclusion still entrapped in its host by measuring its Raman wavenumber shifts which are interpreted through the phonon-mode Grüneisen tensors of the inclusion phase. The calculated inclusion strains can then be used in an elastic model to ca...

The formation and shock history of ureilite meteorites, a relatively abundant type of primitive achondrites, has been debated for decades. For this purpose, the characterization of carbon phases can provide further information on diamond and graphite formation in ureilites, shedding light on the origin and history of this meteorite group. In this w...

Most of our knowledge about the chemical composition of the Earth’s interior is primarily retrieved by indirect observations, experiments and calculations that are limited to simple compositions. Here, the authors present the investigation of inclusions trapped in super deep diamonds as an alternative source of a wealth of information on the chemic...

A thermal-pressure equation of state has been determined for zircon (ZrSiO4) that characterizes its thermoelastic behavior at metamorphic conditions. New pressure-volume (P-V) data from a “Mud Tank” zircon have been collected from 1 bar to 8.47(1) GPa using X-ray diffraction, and elastic moduli were measured from room temperature up to 1172 K by re...

A method for the self-consistent description of the large variations of unit-cell parameters of crystals with pressure and temperature is presented. It employs linearized versions of equations of state (EoSs) together with constraints to ensure internal consistency. The use of polynomial functions to describe the variation of the unit-cell angles i...

Rutile is often found as inclusions in garnet, quartz, and several other rock-forming minerals, and it is also a common accessory phase in high-pressure metamorphic rocks. Its relatively simple structure, chemistry, broad P-T stability field, and its wide occurrence in nature makes it a candidate for the application of elastic geobarometry. However...

A continuously increasing number of research groups are adopting elastic geobarometry for retrieving pressures and temperatures of entrapment of inclusions into a host from both natural and experimental samples. However, a few misconceptions of some of the general concepts underlying elastic geobarometry are still widespread. One is the difference...

The NASA’s MESSENGER mission reported that Mercury surface is mainly composed of basaltic lavas, with small areas composed of residual floating carbon phases due to a primordial magma ocean. In particular, compositional data obtained by X- and Gamma-ray spectrometers highlighted that basaltic lavas have unique characteristics among the differentiat...

Heamanite-(Ce) (IMA 2020-001), ideally (K0.5Ce0.5)TiO3, is a new perovskite-group mineral found as an inclusion in a diamond from the Gahcho Kué mine in the Northwest Territories, Canada. It occurs as brown, translucent single crystals with average maximum dimension of ~80 μm, associated with rutile and calcite. The luster is adamantine and the fra...

Solar System bodies undergo to daily and periodical variations of temperature that mainly depend on their closeness to the Sun. It is known that mineral expansion and contraction due to such variations modify the thermal infrared spectra acquired on solid surfaces. Therefore, it becomes crucial to know the best temperature range at which the acquis...

Current models for elastic geobarometry have been developed with the assumption that the host and/or inclusion minerals are elastically isotropic. This assumption has limited applications of elastic thermobarometry to mineral inclusions contained in cubic quasi‐isotropic host minerals (e.g., garnet). Here, we report a new elastic model that takes i...

Characterizing the pressure and temperature (PT) histories of eclogite–facies rocks is of key importance for unravelling subduction–zone processes at all scales. Accurate PT estimates provide constraints on tectonic and geochemical processes affecting subduction dynamics and help in interpreting the geophysical images of present–day converging plat...

The occurrence of shock-induced diamonds in ureilite meteorites is common and is used to constrain the history of the ureilite parent bodies. We have investigated a fragment of the Kenna ureilite by micro-X-ray diffraction, micro-Raman spectroscopy and scanning electron microscopy to characterize its carbon phases. In addition to olivine and pigeon...

The ultrahigh-pressure (UHP) whiteschists of the Brossasco-Isasca unit (Dora-Maira Massif, Western Alps) provide a natural laboratory in which to compare results from classical pressure (P)–temperature (T) determinations through thermodynamic modelling with the emerging field of elastic thermobarometry. Phase equilibria and chemical composition of...

EntraPT is a web-based application for elastic geobarometry freely accessible at the “Fiorenzo Mazzi” experimental mineralogy lab website (http://www.mineralogylab.com/software/). It provides an easy-to-use tool to calculate the entrapment conditions of inclusions, with error propagation, from the residual strain measured in mineral inclusions. Ent...

Sulfides are the most abundant inclusions in diamonds and a key tool for dating diamond formation via Re-Os isotopic analyses. The manner in which fluids invade the continental lithospheric mantle and the time scale at which they equilibrate with preexisting (protogenetic) sulfides are poorly understood yet essential factors to understanding diamon...

Diamonds containing fluid and mineral inclusions that were trapped during formation are the only natural samples capable of probing the deepest portions of the Earth’s mantle (down to ~800 km depth). In order to precisely interpret the mineralogical and geochemical information they provide, the growth relationships between diamonds and inclusions (...

This study combines the microstructural and petrological analysis of garnet and its inclusions in quartzite‐hosted garnetite from the ultrahigh‐pressure Lago di Cignana metaophiolite (Western Alps). We present a comprehensive record of metamorphism, compaction, and the state of stress during interaction between oceanic metasediments and infiltratin...

EntraPT is a web-based application for elastic geobarometry freely accessible at the “Fiorenzo Mazzi” experimental mineralogy lab website (www.mineralogylab.com/software). It provides an easy-to-use tool to calculate the entrapment conditions of inclusions, with error propagation, from the residual strain measured in mineral inclusions. EntraPT est...

We provide a further algebraic proof that the lines of entrapment conditions for inclusions calculated with the formula of Guiraud and Powell (2006) are not thermodynamic isomekes and therefore do not represent exactly lines of possible entrapment conditions.

The origin of diamonds in ureilite meteorites is a timely topic in planetary geology as recent studies have proposed their formation at static pressures >20 GPa in a large planetary body, like diamonds formed deep within Earth's mantle. We investigated fragments of three diamond-bearing ureilites (two from the Almahata Sitta poly-mict ureilite and...

The pressure dependence of the polarized Raman scattering of quartz was studied under hydrostatic conditions up to 9 GPa. We extended the available pressure calibrations, usually limited to the two most intense peaks, to a larger number of modes, providing polynomial functions that describe the relationship between pressure P and wavenumber shift \...

The structural and chemical properties of zircon inclusions in garnet megablasts from the Dora Maira Massif (Western Alps, Italy) were characterized in detail using charge contrast imaging, Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The aim of this work is to determine to what extent the degree...

IMA No. 2020-001 Heamanite-(Ce) (K0.5Ce0.5)TiO3 As inclusions in a diamond from the Gahcho Kué mine (5034 pipe), Northwest Territories, Canada (63°26′04′′N, 109°11′10′′W) Chiara Anzolini*, William Siva-Jothy, Andrew J. Locock, Fabrizio Nestola, Tonci Balić-Žunić, Matteo Alvaro, Thomas Stachel and D. Graham Pearson E-mail: anzolini@ualberta.ca Perov...

Magnetite–bearing multiphase solid inclusions hosted in metamorphic olivine have been interpreted as final products of the trapping of the aqueous fluid produced by the subduction-zone dehydration of former serpentinites. We provide here a careful analysis performed by micro-focus single–crystal x-ray diffraction of inclusions found in harzburgites...

Live slide presentation.

The search for new nanostructural topologies composed of elemental carbon is driven by technological opportunities as well as the need to understand the structure and evolution of carbon materials formed by planetary shock impact events and in laboratory syntheses. We describe two new families of diamond-graphene (diaphite) phases constructed from...

The conclusion of Zaffiro et al. (2019; Constraints on the Equations of State of stiff anisotropic minerals: rutile, and the implications for rutile elastic barometry. Mineralogical Magazine , 83 , 339–347) that the Mie–Grüneisen–Debye (MGD) Equation of State (EoS) cannot fit the available data for rutile is shown to be incorrect, even though rutil...

In the complex geodynamic processes occurring at convergent plate margins, rocks can be subducted at depth into the Earth experiencing metamorphism. A mineral inhomogeneity entrapped into another mineral, after exhumation to the Earth surface, will exhibit stress and strain fields different from those of the host because of the different thermoelas...

Polarized Raman spectroscopy was applied to garnet hosts which exhibit anomalous birefringence around inclusions of zircon and quartz to elucidate the spatial distribution of the anisotropic strain fields in the vicinity of the host-inclusion boundary. We show that there is a direct relationship between the stress-induced birefringence and the Rama...

Structural refinements from single-crystal X-ray diffraction data are reported for olivine with a composition of Fo100 (forsterite Mg2SiO4, synthetic), Fo80 and Fo62 (~Mg1.6Fe0.4SiO4 and ~Mg1.24Fe0.76SiO4, both natural) at room temperature and high pressure to ~8 GPa. The new results, along with data from the literature on Fo0 (fayalite Fe2SiO4), w...

We have carried out ab initio hybrid Hartree-Fock/Density Functional Theory simulations to determine the structure and vibrational modes of zircon, ZrSiO4, as a function of different applied strains. The changes in phonon-mode wavenumbers are approximately linear in the unit-cell strains, and have been fitted to determine the components of the phon...

Terrestrial analogues are often investigated to get insights into the geological processes occurring on other planetary bodies. Due to its thickness and petrological similarities, the pyroxenitic layer of the 120m-thick magmatic pile Theo’s Flow (Archean Abitibi greenstone belt Ontario, Canada), has always been regarded as the terrestrial analogue...

Mineral inclusions entrapped in other minerals may record the local stresses at the moment of their entrapment in the deep Earth. When rocks are exhumed to the surface of the Earth, residual stresses and strains may still be preserved in the inclusion. If measured and interpreted correctly through elastic geobarometry, they give us invaluable infor...

Magnetic mineral inclusions, as iron oxides or sulfides, occur quite rarely in natural diamonds. Nonetheless, they represent a key tool not only to unveil the conditions of formation of host diamonds, but also to get hints about the paleointensity of the geomagnetic field present at times of the Earth’s history otherwise not accessible. This possib...

Thermal-pressure Equations of State (EoS) such as the Mie-Grüneisen-Debye (MGD) model depend on several assumptions, including the quasi-harmonic approximation (QHA) and a simplified phonon density of states. We show how the QHA is violated by materials exhibiting anisotropic thermal pressure. We also show that at pressures lower than those of the...

Elastic geobarometry makes use of the contrast in elastic proprieties between host and inclusion crystals to determine the entrapment conditions of the inclusions from the residual stress and strain measured in the inclusion when its host is at ambient conditions. The theoretical basis has been developed extensively in the past few years, but an ex...

Mineral inclusions are ubiquitous in metamorphic rocks and elastic models for host‐inclusion pairs have become frequently used tools for investigating pressure‐temperature (P–T) conditions of mineral entrapment. Inclusions can retain remnant pressures (Pinc) that are relatable to their entrapment P–T conditions using an isotropic elastic model and...

Magnetic mineral inclusions, as iron oxides or sulfides, occur quite rarely in natural diamonds. Nonetheless, they represent a key tool not only to unveil the conditions of formation of host diamonds, but also to get hints about the paleointensity of the geomagnetic field present at times of the Earth’s history otherwise not accessible. This possib...