Mike Carroll

Università degli studi di Camerino UNICAM, School of Sciences and Technologies, Faculty Member

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Papers by Mike Carroll

Alkali Feldspar Crystallization Kinetics in Phonolites and Peralkaline Rhyolites

Goldschmidt Abstracts, 2020

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Crystallization and nucleation kinetics in volcanic systems

ABSTRACT The main objective of this experimental study is to constrain and quantitatively model t... more ABSTRACT The main objective of this experimental study is to constrain and quantitatively model the complex solidification process that transforms a magma in a solid material. Of major interest are crystal nucleation and growth driven by isothermal decompression of hydrous magmas, and comparison with results from more abundant crystal growth/nucleation data obtained in isobaric cooling experiments. This research concerns two different volcanic systems, Pantelleria (peralkaline rhyolite) and Stromboli (basalt), to better understand how crystallization kinetics can affect different magma compositions. For Stromboli volcanic system TZM apparatus has been used to perform decompression runs at Bayerisches Geoinstitut in Bayreuth (DE). As for Pantelleria composition, cooling experiments has been done using IHPV devices at ISTO of Orléans (FR), on the basis of previous phase equilibrium work (Di Carlo et al., 2010). First obtained results for Stromboli case show high rates of nucleation and crystal growth during the initial stages of crystallization which were followed by crystal growth at approximately constant number densities as equilibrium was approached. Shapes of crystals growing in melts are controlled by the kinetics of crystallization and may provide information about the degree of undercooling experienced by batches of magma en route to the surface (Lofgren, 1980). The study of crystallization kinetics through phases growth rates (Couch et al., 2003), together with the calculation of nucleation density and nucleation rates (Hammer et al., 1999) represent a step toward the estimation of the time scales of magmatic processes in volcanic systems and the interpretation of shallow magmatic processes. The results for Stromboli suggest average crystal growth timescales on the order of weeks, but this is complicated by clear evidence that some crystals have experienced repeated periods of both dissolution and growth (Landi et al., 2004).

Dimensional, Mechanical and LCA Characterization of Terrazzo Tiles along with Glass and Construction and Demolition Waste (CDW)

Recent Progress in Materials, 2021

In this work, two types of wastes were introduced, namely, glass from municipal waste and Constru... more In this work, two types of wastes were introduced, namely, glass from municipal waste and Construction and Demolition Waste (CDW). The latter, which was obtained from rubble generated by the seismic events occurred in Central Italy in 2016, was introduced in two configurations, the single-layer and the double-layer of the cement-based Terrazzo tiles. A maximum of 77% of waste introduction was proven to be possible, therefore creating the possibility of obtaining construction products including high quantities of secondary raw materials, coupled with a valuable aesthetic aspect. The tiles represent a novel CDW upcycling application and follow the EU recommendations to improve the circular economy in the building sector. In particular, the products obtained showed dimensional conformity in the specifications and mechanical performance in the case of double-layer tiles as required by the envisaged use in the flooring (EN 13748-1). A life cycle analysis (LCA) clarified the possible adva...

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Empirical calibration of the sulphur valence oxygen barometer from natural and experimental glasses: method and applications

Mineralogical Magazine, 1999

New data on sulphur valence and magmatic oxidation state for Central Andean volcanic rocks, in co... more New data on sulphur valence and magmatic oxidation state for Central Andean volcanic rocks, in combination with published data for experimental and natural samples, allow derivation of a simple relationship between magma oxidation state and sulphur speciation. For a number of highly oxidized Central Andean volcanic rocks fO2 has been calculated using magnetite-ilmenite or olivine-spinel pairs and the sulphur valence in glasses has been measured using the peak shift of S-Kα radiation relative to a pyrite standard. Previously published experimental and natural data have been incorporated with a wider range in fO2 and S valence. The variation in sulphur speciation (as S2- or SO42-) as a function of log fO2 is described by an empirical polynomial fit which reproduces the data to within ±0.5 log units and allows use of electron microprobe measurements of the S-Kα wavelength shift for estimation of magmatic oxygen fugacities. This approach is applicable for fO2 between FMQ-2 and FMQ+6, en...

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How to build a legacy of scientific leadership: the HR formula

Goldschmidt2022 abstracts, 2022

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Petrologic experimental data on Vesuvius and Campi Flegrei magmatism

Vesuvius, Campi Flegrei, and Campanian Volcanism, 2020

Abstract Experimental studies of compositions relevant to magmatism at Vesuvius and Campi Flegrei... more Abstract Experimental studies of compositions relevant to magmatism at Vesuvius and Campi Flegrei (CF) provide constraints on the pressure, temperature, and magmatic volatile activities prevailing during various phases of eruption. Such information helps to define pressures (depths) of origin for some well-studied eruptions and differentiation trends that link magma compositions potentially related by crystal–liquid differentiation processes. The presence of mixed magmas and zoned eruptions (magma chambers) may complicate some interpretations, but the phase equilibrium constraints are robust for magma compositions not strongly affected by mixing. Similarly, studies of volatile solubilities in the relatively alkali-rich melt composition characteristic of Vesuvius and CF magmatism can provide valuable constraints for interpreting the composition of melt inclusions (MIs) in phenocrysts of many eruptive products. These experimental data can help to estimate pressures of MI entrapment, the possible importance of hydrosaline brines in some magmas, and degassing processes or CO2-fluxing experienced by melt compositions preserved in MIs.

Tectonic influence on hydrothermal fluid flow in the Laga foredeep Basin (Marche, Italy)

convegno "Natural Silicate Glasses

Crystallization Kinetics of Alkali Feldspar in Peralkaline Rhyolitic Melts: Implications for Pantelleria Volcano

Frontiers in Earth Science, 2020

Peralkaline rhyolites, associated with extensional tectonic settings, are medium to low viscosity... more Peralkaline rhyolites, associated with extensional tectonic settings, are medium to low viscosity magmas that often produce eruptive styles ranging from effusive to highly explosive eruptions. The role of pre-eruptive conditions and crystallization kinetics in influencing the eruptive style of peralkaline rhyolitic magmas has been investigated and debated considering equilibrium conditions. However, experimental constraints on the effect of disequilibrium in crystallization in such magmas are currently lacking in the literature. Therefore, we performed isobaric cooling experiments to investigate alkali feldspar crystallization kinetics in peralkaline rhyolitic melts. Experiments were performed under water-saturated, water-undersaturated, and anhydrous conditions between 25 and 100 MPa, at 670-790 • C and with experimental durations ranging from 0.5 to 420 h. Here we present the first data on crystallization kinetics of alkali feldspar, which is the main crystal phase in peralkaline rhyolitic melts, in order to improve our understanding of the evolutionary timescales of these melts and their ability to shift between effusive and explosive activity. Our experimental results indicate that the alkali feldspar nucleation delay can range from hours to several days as a function of undercooling and H 2 O content in the melt. Thus, a peralkaline rhyolitic magma can be stored at the pre-eruptive conditions for days without important variations of its crystal fraction. This suggests that crystallization may not necessarily play the main role in triggering fragmentation during explosive eruptions of peralkaline rhyolitic magmas.

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Experimental study of monazite solubility in haplogranitic melts: a new model for peraluminous and peralkaline melts

European Journal of Mineralogy, 2019

H2O solubility in pantelleritic melts: pressure and alkali effects

Neues Jahrbuch für Mineralogie - Abhandlungen, 2017

H2O solubility has been experimentally investigated in pantelleritic glasses at 850 °C in the ran... more H2O solubility has been experimentally investigated in pantelleritic glasses at 850 °C in the range 0.5-2.5 kbar. Using a synthetic glass analogue of pantelleritic magma from the Kenya Rift Valley (Ebu-1 in Scaillet &amp; MacDonald 2006) as starting composition, the molar Na/(Na+K) ratio was varied from 0 (Ebu-C) to 0.66 (Ebu-B) and 1 (Ebu-N) at constant total alkali content. The compositional dependence of water solubility as function of Na/(Na+K) was mainly investigated at 850 °C in the pressure interval 0.5-1.5 kbar. H2O solubility in rhyolitic systems is strongly dependent on the Na/(Na+K) ratio (HOLTZ et al. 1995, VETERE et al. 2014), yet such effects for pantellerites are still poorly constrained. Our new results suggest that higher Na favours higher H2O solubility (determined by KFT measurements). This alkali effect has important implications also for other chemical and physical properties of pantelleritic melts such as viscosity (e.g. Stabile et al. 2016). Our new data demonstrate a nearly linear positive correlation between water solubility (wt%) and pressure between 0.5 and 1.5 kbar at 850 °C (slightly above the water-saturated liquidus of the starting composition mixed alkali Ebu-B). The results we present aim to enlarge the experimental water solubility dataset for alkali- and silica-rich melts in order to improve existing predictive models of H2O solubility and eruptive processes (e.g. magma ascent, saturation and degassing). © 2017 E. Schweizerbart&#39;sche Verlagsbuchhandlung, Stuttgart, Germany.

Interactions among magmas and rocks in subduction zone regions: experimental studies from slab to mantle to crust

European Journal of Mineralogy, 1989

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Experimental Study of Silicate-Sulfide Metal Equilibria in Basalts

Preliminary insights from the Acquasanta thermal area (Marche, Italy)

Acquasanta Terme is a thermal area located in the southern part of Marche region (Central Italy),... more Acquasanta Terme is a thermal area located in the southern part of Marche region (Central Italy), within a positive structure in the footwall of the main Central Apennine thrust front. Our preliminary studies on structural analyses, water chemical analyses of major and minor elements, and quantification of water stable isotopes of oxygen and deuterium allowed to: i) distinguish the major fracture sets and the possible reservoir and seal formations; ii) establish a water infiltration altitude; iii) suggest water circulation paths.

Petrological and volcanological constraints on volcanic sulfur emissions to the atmosphere

Volcanism and the Earth's Atmosphere, 2003

ABSTRACT A review of current knowledge about the physics of volcanic eruptions and the experiment... more ABSTRACT A review of current knowledge about the physics of volcanic eruptions and the experimental constraints on sulfur behavior in magmas is presented with the aim of evaluating the range of sulfur yields from major explosive eruptions based on petrological and volcanological data. The so-called petrologic method, used to evaluate syn-eruptive melt degassing, is expanded by also considering the role of a pre-emptive gas phase. It is shown that more than 90% of the atmospheric sulfur loading may come from release of the pre-emptive gas phase during eruptions of intermediate to silicic magmas at subduction-related volcanoes. In contrast, the role of a pre-emptive gas phase may be much less important in more mafic magmas empted in other tectonic settings. Bulk sulfur contents are weakly (spreading-ridges and hot spots) to non-correlated (subduction-zones) with bulk-rock composition. With the exception of some persistently active volcanoes, bulk sulfur contents generally do not exceed 0.5 wt %. The sulfur yields are positively correlated with mass of erupted magma, but the dispersion in sulfur emission for a given empted mass increases progressively as the empted mass decreases. The sulfur yields of single emptive events retrieved from this improved petrologic method are shown to closely agree with independent estimates obtained from analysis of ice cores, optical-depth measurements, and remote-sensing spectroscopic techniques (TOMS and COSPEC).

The Influence of H2O on Volcanic Degassing of Aerosol Forming Elements S, Cl, and F

Special issue-Colston Research Society conference-The degassing history of the Earth-Bristol, UK, 29-31 August 1996-Preface

Quaternary ice sheet thickness, jokulhlaups and rapid depressurization of pillow basalts(on Iceland)

Experimental investigations on the role of sulfur in magmas

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