ORCID Profile
0000-0002-0778-5811
Current Organisation
Macquarie University
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Archaeological Science | Inorganic Geochemistry | Geochemistry | Isotope Geochemistry
Expanding Knowledge in the Earth Sciences | Understanding Australia's Past | Mineral Exploration not elsewhere classified |
Publisher: Elsevier BV
Date: 10-2019
Publisher: Springer Science and Business Media LLC
Date: 09-08-2023
Publisher: Elsevier BV
Date: 11-2021
Publisher: Research Square Platform LLC
Date: 28-02-2023
DOI: 10.21203/RS.3.RS-2610331/V1
Abstract: We present results from high-pressure, high-temperature experiments that generate incipient carbonate melts at mantle conditions (~90km depth and temperatures between 900 - 1050℃). We show that these melts can effectively sequester sulfur, in its oxidised form of sulfate, platinum group elements, and first-row transition metals from mantle lithologies of peridotite and pyroxenite. These primitive oxidised melts may be effective agents to dissolve, redistribute and concentrate sulfur as well as chalcophile metals within the mantle, and from the mantle to shallower regions within the Earth, where localised dynamic physio-chemical processes can lead to ore genesis at various crustal depths. It is proposed that these carbonate-sulfur rich melts may be more widespread than previously thought, and may play a first order role in the metallogenic enhancement of localised and predictable lithospheric domains.
Publisher: MDPI AG
Date: 03-09-2021
DOI: 10.3390/GEOSCIENCES11090372
Abstract: Subduction of oceanic crust buries an average thickness of 300–500 m of sediment that eventually dehydrates or partially melts. Progressive release of fluid/melt metasomatizes the fore-arc mantle, forming serpentinite at low temperatures and phlogopite-bearing pyroxenite where slab surface reaches 700–900 °C. This is sufficiently high to partially melt subducted sediments before they approach the depths where arc magmas are formed. Here, we present experiments on reactions between melts of subducted sediments and peridotite at 2–6 GPa/750–1100 °C, which correspond to the surface of a subducting slab. The reaction of volatile-bearing partial melts derived from sediments with depleted peridotite leads to separation of elements and a layered arrangement of metasomatic phases, with layers consisting of orthopyroxene, mica-pyroxenite, and clinopyroxenite. The selective incorporation of elements in these metasomatic layers closely resembles chemical patterns found in K-rich magmas. Trace elements were imaged using LA-ICP-TOFMS, which is applied here to investigate the distribution of trace elements within the metasomatic layers. Experiments of different duration enabled estimates of the growth of the metasomatic front, which ranges from 1–5 m/ky. These experiments explain the low contents of high-field strength elements in arc magmas as being due to their loss during melting of sedimentary materials in the fore-arc.
Publisher: Research Square Platform LLC
Date: 28-08-2023
DOI: 10.21203/RS.3.RS-2610331/V2
Abstract: We present results from high-pressure, high-temperature experiments that generate incipient carbonate melts at mantle conditions (~ 90 km depth and temperatures between 900–1050°C). We show that these primitive carbonate melts can sequester sulfur in its oxidized form of sulfate, as well as base and precious metals from mantle lithologies of peridotite and pyroxenite. It is proposed that these carbonate-sulfur-rich melts may be more widespread than previously thought, and that they may play a first order role in the metallogenic enhancement of localized lithospheric domains. They act as effective agents to dissolve, redistribute and concentrate metals within discrete domains of the mantle and into shallower regions within the Earth, where dynamic physico-chemical processes can lead to ore genesis at various crustal depths. Green metals could be transported and concentrated into ores by their interaction with low temperature carbonate rich melts.
Publisher: AIP Publishing
Date: 05-2023
DOI: 10.1063/5.0129417
Abstract: The accurate and precise determination of the compositions of silicate glasses formed from melts containing volatile components H2O and CO2 recovered from high-pressure, high-temperature experiments is essential to our understanding of geodynamic processes taking place within the planet. Silicate melts are often difficult to analyze chemically because the formation of quench crystals and overgrowths on silicate phases is rapid and widespread upon quenching of experiments, preventing the formation of glasses in low-SiO2 and volatile-rich compositions. Here, we present experiments conducted in a novel rapid quench piston cylinder apparatus on a series of partially molten low-silica alkaline rock compositions (l roite, basanite, and calk-alkaline basalt) with a range of water contents between 3.5 and 10 wt %. Quench modification of the volatile-bearing silicate glasses is significantly reduced compared to those produced in older piston cylinder apparatuses. The recovered glasses are almost completely free of quench modification and facilitate the determination of precise chemical compositions. We illustrate significantly improved quench textures and provide an analytical protocol that recovers accurate chemical compositions from both poorly quenched and well-quenched silicate glasses.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Springer Science and Business Media LLC
Date: 26-02-2021
DOI: 10.1038/S41467-021-21657-8
Abstract: Sediments play a key role in subduction. They help control the chemistry of arc volcanoes and the location of seismic hazards. Here, we present a new model describing the fate of subducted sediments that explains magnetotelluric models of subduction zones, which commonly show an enigmatic conductive anomaly at the trenchward side of volcanic arcs. In many subduction zones, sediments will melt trenchward of the source region for arc melts. High-pressure experiments show that these sediment melts will react with the overlying mantle wedge to produce electrically conductive phlogopite pyroxenites. Modelling of the Cascadia and Kyushu subduction zones shows that the products of sediment melting closely reproduce the magnetotelluric observations. Melting of subducted sediments can also explain K-rich volcanic rocks that are produced when the phlogopite pyroxenites melt during slab roll-back events. This process may also help constrain models for subduction zone seismicity. Since melts and phlogopite both have low frictional strength, damaging thrust earthquakes are unlikely to occur in the vicinity of the melting sediments, while increased fluid pressures may promote the occurrence of small magnitude earthquakes and episodic tremor and slip.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-05-2019
Abstract: We demonstrate the formation of highly saline mantle fluids by the reaction of subducted sediment with peridotite.
Publisher: MDPI AG
Date: 29-05-2018
DOI: 10.3390/MIN8060234
Publisher: Wiley
Date: 03-2022
DOI: 10.1111/GGR.12421
Publisher: American Astronomical Society
Date: 13-06-2003
DOI: 10.1086/377074
Publisher: Springer Science and Business Media LLC
Date: 22-07-2021
DOI: 10.1038/S41467-021-24750-0
Abstract: Remobilization of sedimentary carbonate in subduction zones modulates arc volcanism emissions and thus Earth’s climate over geological timescales. Although limestones (or chalk) are thought to be the major carbon reservoir subducted to subarc depths, their fate is still unclear. Here we present high-pressure reaction experiments between impure limestone (7.4 wt.% clay) and dunite at 1.3–2.7 GPa to constrain the melting behaviour of subducted natural limestone in contact with peridotite. The results show that although clay impurities significantly depress the solidus of limestone, melting will not occur whilst limestones are still part of the subducting slab. Buoyancy calculations suggest that most of these limestones would form solid-state diapirs intruding into the mantle wedge, resulting in limited carbon flux to the deep mantle ( ~10 Mt C y −1 ). Less than 20% melting within the mantle wedge indicates that most limestones remain stable and are stored in subarc lithosphere, resulting in massive carbon storage in convergent margins considering their high carbon flux (~21.4 Mt C y −1 ). Assimilation and outgassing of these carbonates during arc magma ascent may dominate the carbon flux in volcanic arcs.
Publisher: Elsevier BV
Date: 04-2017
Publisher: Research Square Platform LLC
Date: 03-11-2021
DOI: 10.21203/RS.3.RS-1029408/V1
Abstract: Silicate melts in arc environments are dominated by mafic (low-silica) and silicic (high-silica) compositions, often generating a characteristic bimodal pattern. We investigate the whole arc crust and show that the plutonic lower crust shares the bimodal pattern of melts from volcanoes. This key observation reveals that, contrary to some explanations of bimodal volcanism, variation in mantle source and mantle processes must fundamentally control bimodalism. We also recognise bimodalism in Th/La composition of the whole arc crust and suggest a new working hypothesis: bimodalism originates by melting of distinct sub-arc mantle sources, one dominated by relatively dry peridotite and the other by hydrous pyroxenite. The two groups of primary melts fractionate along distinct liquid lines of descent that lead to relatively dry mafic melts (Th/La~0.1) versus hydrous silicic melts (Th/La .2) by 65–80% fractional crystallisation. Common crustal processes such as crystal fractionation, assimilation, reactive flow and/or magma mixing may also lead to differentiation of both groups.
Publisher: Wiley
Date: 28-12-2020
DOI: 10.1111/GGR.12370
Publisher: Wiley
Date: 08-08-2020
DOI: 10.1002/JQS.3134
Publisher: Elsevier BV
Date: 2018
Publisher: Informa UK Limited
Date: 06-02-2022
Publisher: Elsevier BV
Date: 12-2023
Publisher: Elsevier BV
Date: 11-2021
Publisher: MDPI AG
Date: 31-12-2019
DOI: 10.3390/MIN10010041
Abstract: The generation of strongly potassic melts in the mantle requires the presence of phlogopite in the melting assemblage, while isotopic and trace element analyses of ultrapotassic rocks frequently indicate the involvement of subducted crustal lithologies in the source. However, phlogopite-free experiments that focus on melting of sedimentary rocks and subsequent hybridization with mantle rocks at pressures of 1–3 GPa have not successfully produced melts with K2O wt%–6 wt%, while ultrapotassic igneous rocks reach up to 12 wt% K2O. Accordingly, a two-stage process that enriches K2O and increases K/Na in intermediary assemblages in the source prior to ultrapotassic magmatism seems likely. Here, we simulate this two-stage formation of ultrapotassic magmas using an experimental approach that involves re-melting of parts of an experimental product in a second experiment. In the first stage, reaction experiments containing layered sediment and dunite produced a modally metasomatized reaction zone at the border of a depleted peridotite. For the second-stage experiment, the metasomatized dunite was separated from the residue of the sedimentary rock and transferred to a smaller capsule, and melts were produced with 8 wt%–8.5 wt% K2O and K/Na of 6–7. This is the first time that extremely K-enriched ultrapotassic melts have been generated experimentally from sediments at low pressure applicable to a post-collisional setting.
Publisher: Wiley
Date: 25-02-2021
DOI: 10.1111/GGR.12373
Publisher: Elsevier BV
Date: 07-2016
Start Date: 07-2022
End Date: 06-2024
Amount: $344,864.00
Funder: Australian Research Council
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