Michael Stock

Michael Stock
Trinity College Dublin | TCD · Department of Geology

PhD

About

37
Publications
7,056
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547
Citations
Introduction
Geochemist, igneous petrologist and volcanologist, studying the structure and dynamics of magmatic systems. Assistant Professor in Geochemistry at Trinity College Dublin. Director of the Earth Surface Research Laboratory, conducting geochemical analyses for the GSI Tellus ground survey.
Additional affiliations
September 2019 - present
Trinity College Dublin
Position
  • Professor (Assistant)
June 2016 - September 2019
University of Cambridge
Position
  • Fellow
March 2014 - present
University of Oxford
Position
  • Tutor in Volcanoes and the Environment
Education
October 2012 - March 2016
University of Oxford
Field of study
  • Earth Sciences
September 2007 - June 2011
University of Southampton
Field of study
  • Geology

Publications

Publications (37)
Article
Full-text available
Fluorine and chlorine X‑ray count rates are known to vary significantly during electron probe mi-croanalysis (EPMA) of apatite. Since the rate, timing, and magnitude of this variation are a function of apatite orientation and composition, as well as EPMA operating conditions, this represents a signifi-cant problem for volatile element analysis in a...
Article
Magma reservoirs are thought to grow relatively slowly, assembling incrementally under volatile-saturated conditions. Eruptions may be triggered by injections of volatile-rich melt, or generation of over-pressure due to protracted crystallization. Here, we analyse fluorine, chlorine and water in apatite crystals trapped at different stages of magma...
Article
Full-text available
Volatile elements play an important role in many aspects of the physicochemical architecture of sub-volcanic plumbing systems, from the liquid line of descent to the dynamics of magma storage and eruption. However, it remains difficult to constrain the behaviour of magmatic volatiles on short timescales before eruption using established petrologic...
Article
The 2015 eruption of Wolf volcano was one of the largest eruptions in the Galápagos Islands since the onset of routine satellite‐based volcano monitoring. It therefore provides an excellent opportunity to combine geophysical and petrological data, to place detailed constraints on the architecture and dynamics of sub‐volcanic systems in the western...
Article
Full-text available
Many volcanoes erupt compositionally homogeneous magmas over timescales ranging from decades to millennia. This monotonous activity is thought to reflect a high degree of chemical homogeneity in their magmatic systems, leading to predictable eruptive behaviour. We combine petrological analyses of erupted crystals with new thermodynamic models to ch...
Article
Full-text available
Multidisciplinary investigations are widely considered by the scientific community to be the key strategy for understanding the interplay between magmatic processes and volcanic structures as a primary task for volcanological research. Integrating geophysical, geochemical and geological datasets has the potential to provide accurate constraints on...
Article
Full-text available
Magma is commonly thought to be stored as a crystal-rich mush within vertically extensive, crustal storage regions. A key unknown is how to remobilise and erupt such crystal-rich material, and whether the growth of gas bubbles within the mush could promote remobilisation. In order to investigate this, we need improved constraints on the timing of v...
Article
Despite their relatively low concentration in most oceanic basalts, volatile species (e.g. H2O, CO2 and S) have a disproportionately large influence on a wide range of mantle and magmatic processes. However, constraining the concentration of H2O (and other volatiles) in basaltic magmas is not straightforward as submarine glass analyses are influenc...
Preprint
Despite their relatively low concentration in most oceanic basalts, volatile species (e.g. H2O, CO2 and S) have a disproportionately large influence on a wide range of mantle and magmatic processes. However, constraining the concentration of H2O (and other volatiles) in basaltic magmas is not straightforward as submarine glass analyses are influenc...
Article
Full-text available
Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence. However, a scarcity o...
Article
The physicochemical characteristics of sub-volcanic magma storage regions have important implications for magma system dynamics and pre-eruptive behaviour. The architecture of magma storage regions located directly above high buoyancy flux mantle plumes (such as Kīlauea, Hawai’i and Fernandina, Galápagos) are relatively well understood. However, fa...
Preprint
The physicochemical characteristics of sub-volcanic magma storage regions have important implications for magma system dynamics and pre-eruptive behaviour. The architecture of magma storage regions located directly above high buoyancy flux mantle plumes (such as Kīlauea, Hawaii and Fernandina, Galápagos) are relatively well understood. However, far...
Article
The migration and accumulation of immiscible silicate liquids may play a significant role in the differentiation of crustal magma bodies and the formation of some economic mineral deposits. However, our understanding of the processes that control the segregation of these liquids is currently limited by the short timescales of petrological experimen...
Article
Full-text available
The Upper Zone of the Rustenburg Layered Suite of the Bushveld Complex contains the world's largest Fe-Ti-V±P deposit and formed from the last major injection of magma into the chamber. Quantitative textural analysis of Upper Zone rocks was undertaken to constrain the processes operating during mush formation and solidification, focussing on horizo...
Article
Full-text available
The Upper Zone of the Rustenburg Layered Suite of the Bushveld Complex contains the world’s largest Fe–Ti–V ± P deposit and formed from the last major injection of magma into the chamber. Quantitative textural analysis of Upper Zone rocks was undertaken to constrain the processes operating during mush formation and solidification, focussing on hori...
Article
Full-text available
Despite its relatively temperate climate and stable geography, natural hazards present multiple risks to human activity in the UK. These range from small-scale local occurrences, such as landslides, through regional incidents, such as flooding, to major high impact, low probability events, such as space weather. The impacts of such hazards can be w...
Article
The 1982 and 2015 eruptions were the first at Wolf volcano, Galápagos Archipelago, with eyewitness accounts and satellite imagery. Both eruptions were characterized by a rapid and intense initial phase, with multiple eruptive vents, leading to the formation of large ‘a‘ā lava fields and scarce pāhoehoe mostly associated with the waning phases. The...
Article
The injection of hot magma into a sill can lead to heating and melting of the walls and roof of the reservoir while the injected magma cools and crystallizes. If the crystals are relatively dense, they will try to sediment from the injected magma to form a cumulate layer. In this cumulate layer, the crystals form a porous framework which traps the...
Article
There are clear microstructural differences between mafic plutonic rocks that formed in a dynamic liquid-rich environment, in which crystals can be moved and re-arranged by magmatic currents, and those in which crystal nucleation and growth are essentially in situ and static. Crystalline enclaves, derived from deep crustal mushy zones and erupted i...
Article
Magmatic conditions prior to explosive eruption are often investigated using geochemical signatures in glassy components of pyroclastic deposits and related to magmatic processes at depth. One important process is fractional crystallization, which causes systematic changes to the SiO2/Al2O3 ratio of the residual melt as can be determined by observa...
Preprint
The 1982 and 2015 eruptions are the first at Wolf volcano, Galápagos Archipelago, with eyewitness accounts and satellite imagery. Both eruptions are characterized by a rapid, intense initial phase and multiple eruptive vents leading to the formation of large ‘a‘ā lava fields with scarce pāhoehoe deposits, mostly associated with the waning phases. T...
Conference Paper
A fundamental geochemical signature in a high proportion of volcanic rock components is the SiO2/Al2O3 ratio. The process of fractional crystallization at depth causes predictable, systematic differentiation of SiO2/Al2O3 between crystallizing minerals and the accompanying residual melt, as evidenced in lava mineralogy, experimental and theoretical...
Article
The Campi Flegrei caldera (southern Italy) is one of the most hazardous volcanic systems on Earth, having produced >60 eruptions in the past 15 ka. The caldera remains active and its potential for future eruptions is high, posing a danger to the dense population living nearby. Despite this, our understanding of pre-eruptive processes and the archit...
Article
Volatile elements play an important role in many aspects of the physicochemical architecture of sub-volcanic plumbing systems, from the liquid line of descent to the dynamics of magma storage and eruption. However, it remains difficult to constrain the behaviour of magmatic volatiles on short timescales before eruption using established petrologic...
Article
The Main Ethiopian Rift hosts a number of peralkaline volcanic centres, several of which show signs of recent unrest. Due to the low number of historical eruptions recorded in the region and lack of volcanic monitoring, conditions of magma storage in the Main Ethiopian Rift remain poorly constrained. Aluto is one of these restless volcanic centres...
Conference Paper
Full-text available
Apatite is capable of incorporating all major magmatic volatile species (H2O, CO2, S, Cl and F) into its crystal structure. Analysis of apatite volatile contents can be related to parental magma compositions through the application of pressure and temperature-dependent exchange reactions (Piccoli and Candela, 1994). Once included within phenocrysts...
Data
Here we present the compositons of apatites and hydrous glasses in different "textural associations" from the Astroni 1 eruption of Campi Flegrei. Apatites occur as inclusions within clinopyroxene and biotite phenocrysts and as a microphenocryst phase, surrounded by silicate melt. Hydrous glass analyses include clinopyroxe- and biotite-hosted melt...
Presentation
The apatite crystal structure is capable of incorporating H2O, F and Cl, as well as trace CO2 and sulphur. These can be related to parental magma compositions through application of a series of pressure and temperature-dependent exchange reactions (Piccoli and Candela, 1994), permitting apatite crystals to preserve a record of all major volatile sp...
Article
Full-text available
The mineral apatite can incorporate all of the major magmatic volatile species into its structure. Where melt inclusions are not available, magmatic apatite may therefore represent an opportunity to quantify volatile concentrations in the pre-eruptive melt. We analysed apatites and matrix glasses from andesites and dacites erupted from Santiaguito...
Presentation
Traditionally, magmatic volatile contents have been assessed through interpretation of phase assemblages or analysis of quenched glass or melt inclusions. However, the fidelity of these methods can be compromised by post-entrapment processes such as volatile leakage, devitrification or volatile exchange with their host. This inhibits the use of mel...
Article
Full-text available
The East Scotia Ridge is an active back-arc spreading centre located to the west of the South Sandwich island arc in the Southern Ocean. Initial exploration of the ridge by deep-tow surveys provided the first evidence for hydrothermal activity in a back-arc setting outside of the western Pacific, and we returned in 2010 with a remotely operated veh...
Article
Apatite incorporates variable and significant amounts of halogens (mainly F and Cl) in its crystal structure, which can be used to determine the initial F and Cl concentrations of magmas. The amount of chlorine in the apatite lattice also exerts an important compositional control on the degree of fission-track annealing. Chlorine measurements in ap...
Article
Full-text available
Major overturn within a magma chamber can bring together felsic and mafic magmas, prompting de-volatilisation and acting as the driver for Plinian eruptions. Until now identification of mixing has been limited to analysis of lavas or individual crystals ejected during eruptions. We have recovered partially developed cumulate material ('live' cumula...

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Projects

Projects (2)
Project
Using integrated petrological, geochemical and geophysical techniques to understand magma processing beneath Galápagos volcanoes.
Project
We have been using tephrochronology to constrain the tempo and and magnitude of eruptions from Campi Flegrei caldera, Italy. Mapping the tephra deposits allows us to further constrain the dispersal and provides information on eruption processes. The composition of the deposits (glass and crystals) are also being used to understand more about the magmatic system feeding the eruptions.