ORCID Profile
0000-0002-4726-5714
Current Organisation
Curtin University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Geology | Geochemistry | Structural Geology | Mineralogy and Crystallography | Ore Deposit Petrology | Geotectonics | Isotope Geochemistry | Geochronology And Isotope Geochemistry | Mineralogy And Crystallography | Igneous and Metamorphic Petrology | Geochronology | Functional Materials | Structural Geology | Geochronology | Composite Materials | Chemical Oceanography | Extraterrestrial Geology | Earth Sciences not elsewhere classified | Nanotechnology | Metals and Alloy Materials | Geochemistry not elsewhere classified | Condensed Matter Physics—Structural Properties | Inorganic Geochemistry | Geomagnetism | Exploration Geochemistry | Nanoscale Characterisation | Organic Geochemistry | Geophysics Not Elsewhere Classified | Nanofabrication, Growth and Self Assembly
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Earth Sciences | Mineral Exploration not elsewhere classified | Earth sciences | Precious (Noble) Metal Ore Exploration | Expanding Knowledge in Engineering | Energy Exploration not elsewhere classified | Climate change | Solid Oxide Fuel Cells | Mining and Extraction of Precious (Noble) Metal Ores | Ecosystem Assessment and Management of Coastal and Estuarine Environments | Primary Mining and Extraction of Mineral Resources not elsewhere classified | Integrated circuits and devices | Machined products | Oil and Gas Exploration | Cement and concrete materials | "Stone, ceramics and clay materials" | Titanium Minerals, Zircon, and Rare Earth Metal Ore (e.g. Monazite) Exploration | Expanding Knowledge in the Biological Sciences |
Related Links
Publications
A review of the geology and geodynamic evolution of the Palaeoproterozoic Earaheedy Basin, Western Australia
Publisher: Elsevier BV
Date: 05-2009
Pre-nucleation geochemical heterogeneity within glassy anatectic inclusions and the role of water in glass preservation
Publisher: Springer Science and Business Media LLC
Date: 21-08-2021
Unravelling complex geologic histories using U–Pb and trace element systematics of titanite
Publisher: Elsevier BV
Date: 2019
Hall–Petch Slope in Ultrafine Grained Al-Mg Alloys
Publisher: Springer Science and Business Media LLC
Date: 25-06-2019
Response of cathodoluminescence to crystal-plastic deformation in zircon
Publisher: Elsevier BV
Date: 04-2009
Kinematic reworking and exhumation within the convergent Alpine Orogen
Publisher: Elsevier BV
Date: 04-2003
The source of Dalradian detritus in the Buchan Block, NE Scotland: application of new tools to detrital datasets
Publisher: Geological Society of London
Date: 05-05-2016
DOI: 10.1144/JGS2016-019
Time-resolved, defect-hosted, trace element mobility in deformed Witwatersrand pyrite
Publisher: Elsevier BV
Date: 2018
An investigation of the laser-induced zircon 'matrix effect'
Publisher: Elsevier BV
Date: 11-2016
Cubic zirconia in >2370 °C impact melt records Earth's hottest crust
Publisher: Elsevier BV
Date: 11-2017
Bayesian geological and geophysical data fusion for the construction and uncertainty quantification of 3D geological models
Publisher: Copernicus GmbH
Date: 15-01-2019
DOI: 10.5194/SE-2019-4
Abstract: Abstract. Traditional approaches to develop 3D geological models employ a mix of quantitative and qualitative scientific techniques, which do not fully provide quantification of uncertainty in the constructed models and fail to optimally weight geological field observations against constraints from geophysical data. Here, we demonstrate a Bayesian methodology to fuse geological field observations with aeromagnetic and gravity data to build robust 3D models in a 13.5 × 13.5 km region of the Gascoyne Province, Western Australia. Our approach is validated by comparing model results to independently-constrained geological maps and cross-sections produced by the Geological Survey of Western Australia. By fusing geological field data with magnetics and gravity surveys, we show that at 89 % of the modelled region has 95 % certainty. The boundaries between geological units are characterized by narrow regions with
Mechanical twinning of monazite expels radiogenic lead
Publisher: Geological Society of America
Date: 25-11-2021
DOI: 10.1130/G48400.1
Abstract: Mechanical twins form by the simple shear of the crystal lattice during deformation. In order to test the potential of narrow twins in monazite to record the timing of their formation, we investigated a ca. 1700 Ma monazite grain (from the Sandmata Complex, Rajasthan, India) deformed at ca. 980 Ma, by electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), and atom probe tomography (APT). APT 208Pb/232Th ages indicate that the twin was entirely reset by radiogenic Pb loss during its formation at conditions far below the monazite closure temperature. The results are consistent with a model where Pb is liberated during rupture of rare earth element–oxygen (REE-O) bonds in the large [REE]O9 polyhedra during twinning. Liberated Pb likely migrated along fast diffusion pathways such as crystal defects. The combination of a quantitative microstructural investigation and nanogeochronology provides a new approach for understanding the history of accessory phases.
The geometry and timing of orogenic extension: an example from the Western Italian Alps
Publisher: Wiley
Date: 09-1999
Phase equilibria modelling constraints on P?T conditions during fluid catalysed conversion of granulite to eclogite in the Bergen Arcs, Norway
Publisher: Wiley
Date: 20-12-2018
DOI: 10.1111/JMG.12294
Structural evolution of the High Himalayan Gneiss sequence, Langtang Valley, Nepal
Publisher: Geological Society of London
Date: 1993
Mesoarchaean–Palaeoproterozoic stratigraphic record of the Singhbhum crustal province, eastern India: a synthesis
Publisher: Geological Society of London
Date: 2012
DOI: 10.1144/SP365.3
Construction and systematic assessment of relative deformation histories
Publisher: Elsevier BV
Date: 08-1999
Palaeoproterozoic to Eoarchaean crustal growth in southern Siberia: a Nd-isotope synthesis
Publisher: Geological Society of London
Date: 2009
DOI: 10.1144/SP323.6
Microstructural, trace element and geochronological characterization of TiO2 polymorphs and implications for mineral exploration
Publisher: Elsevier BV
Date: 2018
The IGCP 509 database system: design and application of a tool to capture and illustrate litho- and chrono-stratigraphic information for Palaeoproterozoic tectonic domains, large igneous provinces and
Publisher: Geological Society of London
Date: 2009
DOI: 10.1144/SP323.2
Palaeoproterozoic supercontinents and global evolution: correlations from core to atmosphere
Publisher: Geological Society of London
Date: 2009
DOI: 10.1144/SP323.1
Atom probe tomography analysis of the reference zircon gj-1: An interlaboratory study
Publisher: Elsevier BV
Date: 09-2018
The effects of deformation-induced microstructures on intragrain 40Ar/39Ar ages in potassium feldspar
Publisher: Geological Society of America
Date: 1999
Solar wind contributions to Earth’s oceans
Publisher: Springer Science and Business Media LLC
Date: 29-11-2021
The golden ark: Arsenopyrite crystal plasticity and the retention of gold through high strain and metamorphism
Publisher: Wiley
Date: 21-03-2016
DOI: 10.1111/TER.12206
Cretaceous age, composition, and microstructure of pseudotachylyte in the Otago Schist, New Zealand
Publisher: Informa UK Limited
Date: 03-2010
Superimposed microstructures of pyrite in auriferous quartz veins as fingerprints of episodic fluid infiltration in the Wulong Lode gold deposit, NE China
Publisher: Springer Science and Business Media LLC
Date: 30-03-2022
Rutile compositions in the Kalgoorlie Goldfields and their implications for exploration
Publisher: Informa UK Limited
Date: 10-2011
Compositional modification and trace element decoupling in rutile: Insight from the Capricorn Orogen, Western Australia
Publisher: Elsevier BV
Date: 08-2020
Trace‐element heterogeneity in rutile linked to dislocation structures: Implications for Zr‐in‐rutile geothermometry
Publisher: Wiley
Date: 08-2022
DOI: 10.1111/JMG.12686
Abstract: 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, we investigate trace‐element migration in low‐angle boundaries formed by dislocation creep in rutile within an omphacite vein of the Lago di Cignana unit (Western Alps, Italy). Zr‐in‐rutile thermometry and inclusions of quartz in rutile and of coesite in omphacite constrain the conditions of rutile deformation to around the prograde boundary from high pressure to ultra‐high pressure (~2.7 GPa) at temperatures of 500–565°C. Crystal‐plastic deformation of a large rutile grain results in low‐angle boundaries that generate a total misorientation of ~25°. Dislocations constituting one of these low‐angle boundaries are enriched in common and uncommon trace elements, including Fe and Ca, providing evidence for the diffusion and trapping of trace elements along the dislocation cores. The role of dislocation microstructures as fast‐diffusion pathways must be evaluated when applying high‐resolution analytical procedures as compositional disturbances might lead to erroneous interpretations for Ca and Fe. In contrast, our results indicate a trapping mechanism for Zr.
Geochronological and provenance constraints on the sedimentary rocks hosting the Abra polymetallic deposit, Capricorn Orogen, Western Australia
Publisher: Elsevier BV
Date: 11-2020
In situ multiple sulfur isotope analysis by SIMS of pyrite, chalcopyrite, pyrrhotite, and pentlandite to refine magmatic ore genetic models
Publisher: Elsevier BV
Date: 12-2016
Disorientation control on trace element segregation in fluid-affected low-angle boundaries in olivine
Publisher: Springer Science and Business Media LLC
Date: 07-2021
Constraining absolute deformation ages: the relationship between deformation mechanisms and isotope systematics
Publisher: Elsevier BV
Date: 08-1999
Palaeoproterozoic Supercontinents and Global Evolution
Publisher: Geological Society of London
Date: 2009
DOI: 10.1144/SP323
Electron backscatter diffraction analysis and orientation mapping of monazite
Publisher: Mineralogical Society
Date: 06-2010
DOI: 10.1180/MINMAG.2010.074.3.493
Abstract: Electron backscatter diffraction (EBSD) analysis of monazite requires a comparison of empirically collected electron backscatter patterns (EBSPs) with theoretical diffraction data, or ‘match units’, derived from known crystallographic parameters. Published crystallographic data derived from compositionally varying natural and synthetic monazite are used to calculate ten different match units for monazite. These match units are used to systematically index EBSPs obtained from four natural monazite s les with different compositions. Analyses of EBSD data, derived from the indexing of five and six diffraction bands using each of the ten match units for 10,000 EBSPs from each of the four s les, indicate a large variation in the ability of the different match units to correctly index the different natural s les. However, the use of match units derived from either synthetic Gd or Eu monazite crystallographic data yield good results for three of the four analysed monazites. Comparison of s le composition with published monazite compositions indicates that these match units are likely to yield good results for the EBSD analysis of metamorphic monazite. The results provide a clear strategy for optimizing the acquisition and analysis of EBSD data from monazite but also indicate the need for the collection of new crystallographic structure data and the subsequent generation of more appropriate match units for natural monazite.
Nanoscale constraints on the shock-induced transformation of zircon to reidite
Publisher: Elsevier BV
Date: 03-2019
Nanoscale features revealed by a multiscale characterisation of discordant monazite highlight mobility mechanisms of Th and Pb
Publisher: Springer Science and Business Media LLC
Date: 29-04-2023
Gold, arsenic, and copper zoning in pyrite: A record of fluid chemistry and growth kinetics
Publisher: Geological Society of America
Date: 02-05-2019
DOI: 10.1130/G46114.1
Neoproterozoic hydrothermal activity in the West Australian Craton related to Rodinia assembly or breakup?
Publisher: Elsevier BV
Date: 04-2019
Open-system behaviour of magmatic fluid phase and transport of copper in arc magmas at Krakatau and Batur volcanoes, Indonesia
Publisher: Elsevier BV
Date: 11-2016
A pressure-temperature phase diagram for zircon at extreme conditions
Publisher: Elsevier BV
Date: 02-2017
Constraining kinematic rotation axes in high-strain zones: a potential microstructural method?
Publisher: Geological Society of London
Date: 2005
Assessing the mechanisms of common Pb incorporation into titanite
Publisher: Elsevier BV
Date: 04-2018
The structure of and origin of nodular chromite from the Troodos ophiolite, Cyprus, revealed using high-resolution X-ray computed tomography and electron backscatter diffraction
Publisher: Elsevier BV
Date: 03-2015
Microstructural constraints on magma emplacement and sulfide transport mechanisms
Publisher: GeoScienceWorld
Date: 12-12-2018
DOI: 10.1130/L743.1
Automated mapping of K-feldspar by electron backscatter diffraction and application to 40Ar/39Ar dating
Publisher: Elsevier BV
Date: 10-2008
Atomic worlds: Current state and future of atom probe tomography in geoscience
Publisher: Elsevier BV
Date: 04-2018
Crystal-plastic deformation of zircon: A defect in the assumption of chemical robustness
Publisher: Geological Society of America
Date: 2006
DOI: 10.1130/G22110.1
Isotopic constraints on the cooling history of the Nanga Parbat‐Haramosh Massif and Kohistan arc, western Himalaya
Publisher: American Geophysical Union (AGU)
Date: 04-1995
DOI: 10.1029/94TC02906
Mechanisms of deformation-induced trace element migration in zircon resolved by atom probe and correlative microscopy
Publisher: Elsevier BV
Date: 12-2116
The evolution of the footwall to the Ronda subcontinental mantle peridotites: insights from the Nieves Unit (western Betic Cordillera)
Publisher: Geological Society of London
Date: 22-04-2013
DOI: 10.1144/JGS2012-105
The effect of grain orientation on secondary ion mass spectrometry (SIMS) analysis of rutile
Publisher: Elsevier BV
Date: 03-2012
Thermal history of the Sonnblick Dome, south-east Tauern Window, Austria: Implications for heterogeneous uplift within the Pennine basement
Publisher: Springer Science and Business Media LLC
Date: 12-1993
DOI: 10.1007/BF00191494
Nanogeochronology of discordant zircon measured by atom probe microscopy of Pb-enriched dislocation loops
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-09-2016
Abstract: Atom probe yields geologically meaningful ages from nanoscale Pb-enriched dislocation loops in discordant zircon.
Redistribution of Iron and Titanium in High‐Pressure Ultramafic Rocks
Publisher: American Geophysical Union (AGU)
Date: 11-2017
DOI: 10.1002/2017GC007145
Trench-parallel fast axes of seismic anisotropy due to fluid-filled cracks in subducting slabs
Publisher: Elsevier BV
Date: 06-2009
The geochemical and geochronological implications of nanoscale trace-element clusters in rutile
Publisher: Geological Society of America
Date: 21-07-2020
DOI: 10.1130/G48017.1
Abstract: The geochemical analysis of trace elements in rutile (e.g., Pb, U, and Zr) is routinely used to extract information on the nature and timing of geological events. However, the mobility of trace elements can affect age and temperature determinations, with the controlling mechanisms for mobility still debated. To further this debate, we use laser-ablation–inductively coupled plasma–mass spectrometry and atom probe tomography to characterize the micro- to nanoscale distribution of trace elements in rutile sourced from the Capricorn orogen, Western Australia. At the & µm scale, there is no significant trace-element variation in single grains, and a concordant U-Pb crystallization age of 1872 ± 6 Ma (2σ) shows no evidence of isotopic disturbance. At the nanoscale, clusters as much as 20 nm in size and enriched in trace elements (Al, Cr, Pb, and V) are observed. The 207Pb/206Pb ratio of 0.176 ± 0.040 (2σ) obtained from clusters indicates that they formed after crystallization, potentially during regional metamorphism. We interpret the clusters to have formed by the entrapment of mobile trace elements in transient sites of radiation damage during upper hibolite facies metamorphism. The entrapment would affect the activation energy for volume diffusion of elements present in the cluster. The low number and density of clusters provides constraints on the time over which clusters formed, indicating that peak metamorphic temperatures are short-lived, & m.y. events. Our results indicate that the use of trace elements to estimate volume diffusion in rutile is more complex than assuming a homogeneous medium.
Direct age constraints on the magnetism of Jack Hills zircon
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-01-2023
Abstract: A potential record of Earth’s magnetic field going back 4.2 billion years (Ga) ago is carried by magnetite inclusions in zircon grains from the Jack Hills. This magnetite may be secondary in nature, however, meaning that the magnetic record is much younger than the zircon crystallization age. Here, we use atom probe tomography to show that Pb-bearing nanoclusters in magnetite-bearing Jack Hills zircons formed during two discrete events at 3.4 and Ga. The older population of clusters contains no detectable Fe, whereas roughly half of the younger population of clusters is Fe bearing. This result shows that the Fe required to form secondary magnetite entered the zircon sometime after 3.4 Ga and that remobilization of Pb and Fe during an annealing event occurred more than 1 Ga after deposition of the Jack Hills sediment at 3 Ga. The ability to date Fe mobility linked to secondary magnetite formation provides new possibilities to improve our knowledge of the Archean geodynamo.
Developing Atom Probe Tomography of Phyllosilicates in Preparation for Extra‐Terrestrial Sample Return
Publisher: Wiley
Date: 07-05-2021
DOI: 10.1111/GGR.12382
Abstract: Hydrous phyllosilicate minerals, including the serpentine subgroup, are likely to be major constituents of material that will be bought back to Earth by missions to Mars and to primitive asteroids Ryugu and Bennu. Small quantities ( 60 g) of micrometre‐sized, internally heterogeneous material will be available for study, requiring minimally destructive techniques. Many conventional methods are unsuitable for phyllosilicates as they are typically finely crystalline and electron beam‐sensitive resulting in amorphisation and dehydration. New tools will be required for nanoscale characterisation of these precious extra‐terrestrial s les. Here we test the effectiveness of atom probe tomography (APT) for this purpose. Using lizardite from the Ronda peridotite, Spain, as a terrestrial analogue, we outline an effective analytical protocol to extract nanoscale chemical and structural measurements of phyllosilicates. The potential of APT is demonstrated by the unexpected finding that the Ronda lizardite contains SiO‐rich nanophases, consistent with opaline silica that formed as a by‐product of the serpentinisation of olivine. Our new APT approach unlocks previously unobservable nanominerals and nanostructures within phyllosilicates owing to resolution limitations of more established imaging techniques. APT will provide unique insights into the processes and products of water/rock interaction on Earth, Mars and primitive asteroids.
Time-strain evolution of shear zones from petrographically constrained Rb–Sr muscovite analysis
Publisher: Elsevier BV
Date: 2023
Inclusion-localised crystal-plasticity, dynamic porosity, and fast-diffusion pathway generation in zircon
Publisher: Elsevier BV
Date: 02-2012
Etching of fission tracks in monazite: An experimental study
Publisher: Wiley
Date: 19-03-2019
DOI: 10.1111/TER.12382
Nanoscale processes of trace element mobility in metamorphosed zircon
Publisher: Springer Science and Business Media LLC
Date: 24-10-2019
Post-accretionary exhumation of the Meguma terrane relative to the Avalon terrane in the Canadian Appalachians
Publisher: Elsevier BV
Date: 11-2018
Deformation in a complex crustal-scale shear zone
Publisher: Geological Society of London
Date: 2004
Atom probe microscopy of zinc isotopic enrichment in ZnO nanorods
Publisher: AIP Publishing
Date: 02-2017
DOI: 10.1063/1.4976299
Abstract: We report on atomic probe microscopy (APM) of isotopically enriched ZnO nanorods that measures the spatial distribution of zinc isotopes in sections of ZnO nanorods for natural abundance natZnO and 64Zn and 66Zn enriched ZnO nanorods. The results demonstrate that APM can accurately quantify isotopic abundances within these nanoscale structures. Therefore the atom probe microscope is a useful tool for characterizing Zn isotopic heterostructures in ZnO. Isotopic heterostructures have been proposed for controlling thermal conductivity and also, combined with neutron transmutation doping, they could be key to a novel technology for producing p-n junctions in ZnO thin films and nanorods.
High-strain zone deformation in the southern Capricorn Orogen, Western Australia: kinematics and age constraints
Publisher: Elsevier BV
Date: 2004
The initiation and development of metamorphic foliation in the Otago Schist, Part 2: evidence from quartz grain‐shape data
Publisher: Wiley
Date: 21-07-2005
Evolution of the Singhbhum Craton and supracrustal provinces from age, isotopic and chemical constraints
Publisher: Elsevier BV
Date: 06-2019
Footprint of a large intracontinental rifting event: Coupled detrital zircon geochronology and geochemistry from the Mesoproterozoic Collier Basin, Western Australia
Publisher: Elsevier BV
Date: 11-2018
Nebula sulfidation and evidence for migration of free-floating refractory metal nuggets revealed by atom probe microscopy
Publisher: Geological Society of America
Date: 26-07-2017
DOI: 10.1130/G39075.1
Atom Probe Tomography: Development and Application to the Geosciences
Publisher: Wiley
Date: 26-02-2020
DOI: 10.1111/GGR.12313
A distant magmatic source for Cretaceous karst bauxites of Southern Apennines (Italy), revealed through SHRIMP zircon age dating
Publisher: Wiley
Date: 12-04-2012
Nanoscale gold clusters in arsenopyrite controlled by growth rate not concentration: Evidence from atom probe microscopy
Publisher: Mineralogical Society of America
Date: 08-2016
Subsurface deposition of Cu-rich massive sulphide underneath a Palaeoproterozoic seafloor hydrothermal system—the Red Bore prospect, Western Australia
Publisher: Springer Science and Business Media LLC
Date: 02-2018
Best practices for reporting atom probe analysis of geological materials
Publisher: Wiley
Date: 12-2018
Temporal constraints on Fe mobility in Jack Hills zircon
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-14336
Abstract: Ancient detrital zircon grains containing magnetite inclusions have the potential to record the Earth& #8217 s magnetic field as far back as the Hadean. However, this requires magnetite to be either a primary inclusion or to be a secondary inclusion that forms shortly after zircon crystallization. Microstructural and TEM analysis of Jack Hills zircon show that magnetite, the magnetic recorder in these zircon crystals, is secondary in nature and is associated with the mobility of Fe. However, the timing of Fe mobility within Jack Hills zircon is poorly constrained. Here we undertake nanoscale characterization of highly magnetic zones of zircon, identified by quantum diamond microscopy (QDM), using atom probe tomography (APT). The APT data show the presence of Pb-bearing nanoclusters and these record isotopic compositions consistent with formation during two discrete thermal events at 3.4 Ga and 2 Ga. The older population of clusters contain no detectable Fe. However, the younger population of clusters are Fe-bearing. This result shows that the Fe required to form secondary magnetite was not present in the zircon prior to 3.4 Ga and that remobilization of Pb and Fe, the latter associated with magnetite formation, took place after 2 Ga, during an annealing event that took place more than one billion years after deposition of the Jack Hills sediment at 3 Ga. This use of APT to date Fe mobility provides a novel approach to temporally constrain the formation of intragranular secondary magnetite inclusions in highly magnetic areas of zircon grains.
A new method for dating impact events – Thermal dependency on nanoscale Pb mobility in monazite shock twins
Publisher: Elsevier BV
Date: 12-2021
Application of younging tables to the construction of relative deformation histories—1: Fracture systems
Publisher: Elsevier BV
Date: 10-2000
Trace-element segregation to dislocation loops in experimentally heated zircon
Publisher: Mineralogical Society of America
Date: 12-2021
DOI: 10.2138/AM-2021-7654
Abstract: To evaluate the mechanisms driving nanoscale trace element mobility in radiation-damaged zircon, we analyzed two well-characterized Archean zircons from the Kaapvaal Craton (southern Africa): one zircon remained untreated and the other was experimentally heated in the laboratory at 1450 °C for 24 h. Atom probe tomography (APT) of the untreated zircon reveals homogeneously distributed trace elements. In contrast, APT of the experimentally heated zircon shows that Y, Mg, Al, and Pb+Yb segregate to a set of two morphologically and crystallographically distinct cluster populations that range from 5 nm tori to 25 nm toroidal polyhedra, which are confirmed to be dislocation loops by transmission electron microscopy (TEM). The dislocation loops lie in {100} and {001} planes the edges are aligned with & & , & & , and & & . The largest loops (up to 25 nm diameter) are located in {100} and characterized by high concentrations of Mg and Al, which are aligned with & & . The 207Pb/206Pb measured from Pb atoms located within all of the loops (0.264 ± 0.025 1σ) is consistent with present-day segregation and confirms that the dislocation loops formed during our experimental treatment. These experimentally induced loops are similar to clusters observed in zircon affected by natural geologic processes. We interpret that differences in cluster distribution, density, and composition between experimentally heated and geologically affected zircon are a function of the radiation dose, the pressure-temperature-time history, and the original composition of the zircon. These findings provide a framework for interpreting the significance of clustered trace elements and their isotopic characteristics in zircon. Our findings also suggest that the processes driving cluster formation in zircon can be replicated under laboratory conditions over human timescales, which may have practical implications for the mineralogical entrapment of significant nuclear elements.
Laser-probe 40Ar/39Ar investigation of a pseudotachylyte and its host rock from the Outer Isles thrust, Scotland
Publisher: Geological Society of America
Date: 1994
Neoproterozoic reworking of the Palaeoproterozoic Capricorn Orogen of Western Australia and implications for the amalgamation of Rodinia
Publisher: Geological Society of London
Date: 2009
DOI: 10.1144/SP327.18
Deformation-related microstructures in magmatic zircon and implications for diffusion
Publisher: Springer Science and Business Media LLC
Date: 05-08-2008
Xenotime at the Nanoscale: U‐Pb Geochronology and Optimisation of Analyses by Atom Probe Tomography
Publisher: Wiley
Date: 18-07-2021
DOI: 10.1111/GGR.12398
Abstract: Xenotime (YPO 4 ) is an accessory phase common in low to high‐temperature geological environments. Xenotime is an established geochronometer, though its small size, low modal abundance and textural complexity make it more difficult to analyse with traditional techniques but makes a prime candidate for nanoscale analysis. In this study, we develop an atom probe tomography (APT) protocol to determine the 206 Pb/ 238 U and 207 Pb/ 206 Pb ages of micro‐scale xenotime crystals with analytical volumes four to six orders of magnitude smaller than typical geochronology techniques. A linear correlation between the 206 Pb/ 238 U fractionation and 238 UO 2 2+ / 238 UO 2+ was used to correct for the atom probe instrument parameters variability between specimens. For 207 Pb/ 206 Pb ages, we employed two methods of background correction owing to the 206 Pb 2+ thermal tail contribution to the 207 Pb 2+ counts: A constant background correction for the younger (˜ 1000 Ma) Y1 reference material and a variable correction of background for Archaean age reference material xtc to correct for the thermal tail influence. This contribution also proposes strategies for optimisation of xenotime analysis using APT and permits us to explore the various geological problems in the nanoscale realm. This methodology potentially allows determining the age of small xenotime crystals in sedimentary rocks, low metamorphic grade settings and deformation microstructures.
Quantitative characterization of plastic deformation of zircon and geological implications
Publisher: Springer Science and Business Media LLC
Date: 06-01-2007
Electron backscatter diffraction analysis of zircon: A systematic assessment of match unit characteristics and pattern indexing optimization
Publisher: Mineralogical Society of America
Date: 2008
DOI: 10.2138/AM.2008.2658
A terrestrial perspective on usingex situshocked zircons to date lunar impacts
Publisher: Geological Society of America
Date: 10-2015
DOI: 10.1130/G37059.1
Relationship between microstructures and grain-scale trace element distribution in komatiite-hosted magmatic sulphide ores
Publisher: Elsevier BV
Date: 2014
Quartz inclusions in garnet from high-temperature metamorphic rocks change their shape
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-4143
Abstract: & & Trapped and sheltered inside other crystals, mineral inclusions preserve fundamental and otherwise lost information on the geological history of our planet. In the last decade, quartz inclusions in garnet have become a fundamental tool to estimate pressure and temperature of metamorphic rocks at the time of inclusion entrapment. In these approaches, as well as in all other applications, inclusions are regarded as immutable objects and the possibility of a change in their shape has never been considered.& & & & With a detailed characterization of s les from greenschist and granulite facies, performed by optical and electron microscopy, EBSD, X-ray tomographic microscopy, laser Raman spectroscopy and FIB serial slicing, we show that after being trapped with irregular (& #8220 scalloped& #8221 ) shape in low-temperature rocks, quartz inclusions in garnet from granulites formed at 750-900 & #176 C and various pressures acquired a polyhedral & #8220 negative crystal& #8221 shape imposed by the host garnet, and almost exclusively defined by the facets of dodecahedron and icositetrahedron. A similar behaviour is also observed in biotite inclusions. The 3-fold and 4-fold morphological symmetry axes of the polyhedral negative crystals are parallel to corresponding crystallographic axes in the host garnet.& & & & The systematic presence of a fluid film at the quartz-garnet boundary is not supported by Raman and FIB investigation.& & & & Strengthened by microstructures indicating the process of & #8220 necking down& #8221 of polycrystalline quartz inclusions, our data support that - like in fluid inclusions changing shape to negative crystals - shape maturation of mineral inclusions occurs by temperature-assisted dissolution-precipitation via grain boundary diffusion. This process tends to minimize the surface free energy of the host-inclusion system by forming energetically favored facets and by decreasing the inclusion surface/volume and aspect ratios.& & & & Optical investigation of numerous s les of worldwide provenance suggests that the negative crystal shape of quartz inclusions in garnet from granulites is a widespread microstructure that underpins a systematic phenomenon so far overlooked.& &
Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements
Publisher: Elsevier BV
Date: 04-2021
Detecting Micro‐ and Nanoscale Variations in Element Mobility in High‐Grade Metamorphic Rocks
Publisher: Wiley
Date: 12-2017
The Optimization of Zircon Analyses by Laser-Assisted Atom Probe Microscopy: Insights from the 91500 Zircon Standard
Publisher: Wiley
Date: 12-2018
Proterozoic cooling and exhumation of the northern central Halls Creek Orogen, Western Australia: constraints from a reconnaissance 40Ar/39Ar study
Publisher: Wiley
Date: 08-2004
Crystallographic Texture and Substructural Phenomena in 316 Stainless Steel Printed by Selective Laser Melting
Publisher: MDPI AG
Date: 09-06-2023
DOI: 10.3390/MA16124289
Abstract: There is a fast-growing interest in the use of selective laser melting (SLM) for metal/alloy additive manufacturing. Our current knowledge of SLM-printed 316 stainless steel (SS316) is limited and sometimes appears sporadic, presumably due to the complex interdependent effects of a large number of process variables of the SLM processing. This is reflected in the discrepant findings in the crystallographic textures and microstructures in this investigation compared to those reported in the literature, which also vary among themselves. The as-printed material is macroscopically asymmetric in terms of both structure and crystallographic texture. The and crystallographic directions align parallel with the SLM scanning direction (SD) and build direction (BD), respectively. Likewise, some characteristic low-angle boundary features have been reported to be crystallographic, while this investigation unequivocally proves them to be non-crystallographic, since they always maintain an identical alignment with the SLM laser scanning direction, irrespective of the matrix material’s crystal orientation. There are also 500 ± 200 nm columnar or cellular features, depending on the cross-section, which are generally found all over the s le. These columnar or cellular features are formed with walls made of dense packing of dislocations entangled with Mn-, Si- and O-enriched amorphous inclusions. They remain stable after ASM solution treatments at a temperature of 1050 °C, and therefore, are capable of hindering boundary migration events of recrystallization and grain growth. Thus, the nanoscale structures can be retained at high temperatures. Large 2–4 μm inclusions form during the solution treatment, within which the chemical and phase distribution are heterogeneous.
Enhanced diffusion of Uranium and Thorium linked to crystal plasticity in zircon
Publisher: Springer Science and Business Media LLC
Date: 12-2006
Ion-probe dating of 1.2Ga collision and crustal architecture in the Namaqua-Natal Province of southern Africa
Publisher: Elsevier BV
Date: 09-2007
Analysis of Natural Rutile (TiO2) by Laser-assisted Atom Probe Tomography
Publisher: Oxford University Press (OUP)
Date: 02-2019
DOI: 10.1017/S1431927618015477
Abstract: Since the introduction of laser-assisted atom probe, analysis of nonconductive materials by atom probe tomography (APT) has become more routine. To obtain high-quality data, a number of acquisition variables needs to be optimized for the material of interest, and for the specific question being addressed. Here, the rutile (TiO 2 ) reference material ‘Windmill Hill Quartzite,’ used for secondary ion mass spectrometry U–Pb dating and laser-ablation inductively coupled plasma mass spectrometry, was analyzed by laser-assisted APT to constrain optimal running conditions. Changes in acquisition parameters such as laser energy and detection rate are evaluated in terms of their effect on background noise, ionization state, hit-multiplicity, and thermal tails. Higher laser energy results in the formation of more complex molecular ions and affects the ionization charge state. At lower energies, background noise and hit-multiplicity increase, but thermal tails shorten. There are also correlations between the acquisition voltage and several of these metrics, which remain to be fully understood. The results observed when varying the acquisition parameters will be discussed in detail in the context of utilizing APT analysis of rutile within geology.
Direct Observation of Nanoparticulate Goethite Recrystallization by Atom Probe Analysis of Isotopic Tracers
Publisher: American Chemical Society (ACS)
Date: 28-10-2019
Abstract: Goethite (α-FeOOH) is dispersed throughout the earth's surface, and its propensity to recrystallize in aqueous solutions determines whether this mineral is a source or sink for critical trace elements in the environment. Under reducing conditions, goethite commonly coexists with aqueous Fe(II) (Fe(II)
Rubble pile asteroids are forever
Publisher: Proceedings of the National Academy of Sciences
Date: 23-01-2023
Abstract: Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much more abundant than previously thought in the solar system. Although monolithic asteroids that are a kilometer in diameter have been predicted to have a lifespan of few 100 million years, it is currently not known how durable rubble pile asteroids are. Here, we show that rubble pile asteroids can survive ambient solar system bombardment processes for extremely long periods and potentially 10 times longer than their monolith counterparts. We studied three regolith dust particles recovered by the Hayabusa space probe from the rubble pile asteroid 25143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, atom probe tomography, and 40 Ar/ 39 Ar dating techniques. Our results show that the particles have only been affected by shock pressure of ca. 5 to 15 GPa. Two particles have 40 Ar/ 39 Ar ages of 4,219 ± 35 and 4,149 ± 41 My and when combined with thermal and diffusion models these results constrain the formation age of the rubble pile structure to ≥4.2 billion years ago. Such a long survival time for an asteroid is attributed to the shock-absorbent nature of rubble pile material and suggests that rubble piles are hard to destroy once they are created. Our results suggest that rubble piles are probably more abundant in the asteroid belt than previously thought and provide constrain to help develop mitigation strategies to prevent asteroid collisions with Earth.
Trace-element migration during crystal-plastic deformation in UHP rutile: dislocations in low-angle boundaries as high-diffusivity pathways.
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-9404
Abstract: & & The trace-element composition of rutile is commonly used to constrain & em& P-T-t& /em& conditions for a wide range of metamorphic systems. Recent studies have highlighted the importance of micro- and nanostructures in the redistribution of trace elements in rutile via high-diffusivity pathways and dislocation-impurity associations. In this contribution, we investigate the effect of crystal-plastic deformation of rutile on its composition by combining microstructural and petrological analyses with atom probe tomography. The studied s le is from an omphacite vein of the ultrahigh-pressure metamorphic Lago di Cignana unit, Western Alps, Italy. Zr-in-rutile thermometry and inclusions of quartz in rutile and of coesite in omphacite constrain rutile deformation to around the prograde HP-UHP boundary at 500& #8211 & #176 C. Crystal-plastic deformation of a large rutile grain resulted in low-angle boundaries that generate a total misorientation of ~25& #176 . Dislocations constituting the low-angle boundary are enriched in common (Fe, Zr) and uncommon trace elements (Ca). The Ca is interpreted to be derived from the grain exterior, suggesting diffusion of trace elements along the dislocation cores. The potential for dislocation microstructures to act as fast diffusion pathways must be evaluated when applying traditional geochemical analyses as compositional disturbances caused by the presence of dislocation might lead to erroneous interpretations.& &
Relationship among titanium, rare earth elements, U-Pb ages and deformation microstructures in zircon: Implications for Ti-in-zircon thermometry
Publisher: Elsevier BV
Date: 2011
Isotopic constraints on fluid evolution and ore precipitation in a sediment-hosted Pb-Ag-Ba-Zn-Cu-Au deposit in the Capricorn Orogen, Western Australia
Publisher: Elsevier BV
Date: 09-2018
Precambrian reidite discovered in shocked zircon from the Stac Fada impactite, Scotland
Publisher: Geological Society of America
Date: 21-08-2015
DOI: 10.1130/G37066.1
Cr-spinel records metasomatism not petrogenesis of mantle rocks
Publisher: Springer Science and Business Media LLC
Date: 08-11-2019
DOI: 10.1038/S41467-019-13117-1
Abstract: Mantle melts provide a window on processes related to global plate tectonics. The composition of chromian spinel (Cr-spinel) from mafic-ultramafic rocks has been widely used for tracing the geotectonic environments, the degree of mantle melting and the rate of mid-ocean ridge spreading. The assumption is that Cr-spinel’s core composition (Cr# = Cr/(Cr + Al)) is homogenous, insensitive to post-formation modification and therefore a robust petrogenetic indicator. However, we demonstrate that the composition of Cr-spinel can be modified by fluid/melt-rock interactions in both sub-arc and sub-mid oceanic mantle. Metasomatism can produce Al-Cr heterogeneity in Cr-spinel that lowers the Cr/Al ratio, and therefore modifies the Cr#, making Cr# ineffective as a geotectonic and mantle melting indicator. Our analysis also demonstrates that Cr-spinel is a potential sink for fluid-mobile elements, especially in subduction zone environments. The heterogeneity of Cr# in Cr-spinel can, therefore, be used as an excellent tracer for metasomatic processes.
Deformed monazite yields high-temperature tectonic ages
Publisher: Geological Society of America
Date: 05-2015
DOI: 10.1130/G36533.1
Metallogeny and its link to orogenic style during the Nuna supercontinent cycle
Publisher: Geological Society of London
Date: 07-2015
DOI: 10.1144/SP424.5
Nanoscale distribution of Pb in monazite revealed by atom probe microscopy
Publisher: Elsevier BV
Date: 02-2018
Nanoscale resetting of the Th/Pb system in an isotopically-closed monazite grain: A combined atom probe and transmission electron microscopy study
Publisher: Elsevier BV
Date: 2019
Defining the Potential of Nanoscale Re-Os Isotope Systematics Using Atom Probe Microscopy
Publisher: Wiley
Date: 07-06-2018
DOI: 10.1111/GGR.12216
40Ar/39Ar ages in deformed potassium feldspar: evidence of microstructural control on Ar isotope systematics
Publisher: Springer Science and Business Media LLC
Date: 05-2001
A 40Ar/39Ar laser probe study of micas from the Sesia Zone, Italian Alps: implications for metamorphic and deformation histories
Publisher: Wiley
Date: 07-1996
Extensional episodes in the Paleoproterozoic Capricorn Orogen, Western Australia, revealed by petrogenesis and geochronology of mafic–ultramafic rocks
Publisher: Elsevier BV
Date: 03-2018
Bayesian geological and geophysical data fusion for the construction and uncertainty quantification of 3D geological models
Publisher: Elsevier BV
Date: 2021
Resolution of impact‐related microstructures in lunar zircon: A shock‐deformation mechanism map
Publisher: Wiley
Date: 16-12-2011
Mineral inclusions are not immutable: Evidence of post-entrapment thermally-induced shape change of quartz in garnet
Publisher: Elsevier BV
Date: 02-2021
Nanoscale deformation twinning in xenotime, a new shocked mineral, from the Santa Fe impact structure (New Mexico, USA)
Publisher: Geological Society of America
Date: 23-08-2016
DOI: 10.1130/G38179.1
Heterogeneous excess argon and Neoproterozoic heating in the Usagaran Orogen, Tanzania, revealed by single grain 40Ar/39 Ar thermochronology
Publisher: Elsevier BV
Date: 06-2004
Nanoscale evidence of metamorphism – insights from natural and experimentally-treated zircon 
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-3036
Abstract: & & Nanoscale analyses of zircon have demonstrated that trace elements, including Pb, can be mobilized to discrete sites in radiation damaged zircon. Although several mechanisms for trace element mobility and segregation in zircon have been proposed, most of this work has been conducted on zircon grains with complex geologic histories, making it difficult to directly determine the mechanisms driving trace element mobility and segregation in zircon. To test among the existing hypotheses for mechanisms driving trace element mobility and segregation, we analyzed both untreated and experimentally heated (1450& #176 C for 24h) Archean zircon using atom probe tomography and transmission electron microscopy (TEM). The s le has a simple, well-characterized thermal history, with no significant thermal events since original crystallization. Despite a high calculated radiation dose (& x 10& sup& & /sup& a/g), the untreated zircon does not contain anomalous nanoscale features. In contrast, the experimentally heated zircon contains abundant clusters of Y, Mg, Al, Pb + Yb that range from 5 nm to 25 nm in diameter with toroidal polyhedral morphologies. The & sup& & /sup& Pb/& sup& & /sup& Pb measured from Pb atoms located within these features is consistent with present-day segregation, thus confirming that these nanoscale features were produced by experimental heating in the laboratory. TEM analysis determined that the clusters are dislocation loops, and that cluster morphology is therefore crystallographically controlled. The largest loops are located in {100} and contain high concentrations of Mg and Al.& & & & These experimentally induced, trace-element-enriched clusters are similar in size, morphology, composition, and crystallographic orientation to clusters observed in zircon affected by natural geologic processes (cf. Valley et al., 2015 Peterman et al., 2016). Although the calculated radiation doses for all analyzed grains are high, comparison of the nanoscale features indicates no apparent correlation between the radiation dose and the density or distribution of clusters. We also observe that trace-element-enriched clusters are conspicuously absent from zircon grains that lack younger igneous or metamorphic rims. These findings suggest that the pressure-temperature-time (P-T-t) history and the dT/dt significantly impact both the nanoscale redistribution of trace elements and the density of these features within zircon. Systematic evaluation of the composition and distribution of these features provides a framework for understanding the nanoscale record of metamorphism.& & & & & & & & & References:& & & & Peterman, E.M., Reddy, S.M, Saxey, D.W., Snoeyenbos, D.R., Rickard, W.D.A., Fougerouse, D., and Kylander-Clark, A.R.C. (2016) Nanogeochronology of discordant zircon measured by atom probe microscopy of Pb-enriched dislocation loops. Science Advances, 2, e:1601218.& & & & Valley, J.W., Reinhard, D.A., Cavosie, A.J., Ushikubo, T., Lawrence, D.F., Larson, D.J., Kelly, T.F., Snoeyenbos, DR., and Strickland, A. (2015) Nano-and micro-geochronology in Hadean and Archean zircons by atom-probe tomography and SIMS: New tools for old minerals. American Mineralogist, 100, 1355-1377.& &
Shocker: xenotime can date impacts
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-1082
Abstract: Constraining precise ages for impact events is crucial in establishing Earth& #8217 s history, and several geochronometers have been developed to date impacts. We present electron backscatter diffraction (EBSD), sensitive high-resolution ion microprobe (SHRIMP) and atom probe tomography (APT) data from shocked xenotime [(Y,HREE)PO4] collected from two impact sites to investigate the potential of xenotime as an impact geochronometer. A detrital xenotime grain from the Vredefort dome (South Africa) contains planar fractures, planar deformation bands and {112} twinning, the latter of which are diagnostic shock microstructures. However, APT analysis from the twin domains and also from the host yielded no evidence of Pb mobility at the nanometer scale during the impact. SHRIMP analysis (n=24) on the grain yielded a discordia with an upper intercept of 3136 & #177 110 Ma and an imprecise lower intercept of 1793 & #177 280 Ma. These correspond, respectively, to the bedrock age and a post-impact, cryptic terrane-wide fluid infiltration event. Three neoblastic grains from the Araguainha dome (Brazil) experienced partial to complete recrystallisation. The least recrystallised grain yields the oldest 238U/206Pb age of 479 & #177 26 Ma, whereas a completely recrystallised neoblastic grain gave an age of 257 & #177 11 Ma. & APT analysis on the latter grain showed different nanoscale features that shed light on Pb mobility during shock deformation and recrystallisation. & Based on observations of nanoscale Pb mobility and the correlation between recrystallisation and isotopic resetting, and prior published ages, we interpret 257 & #177 11 Ma to date the impact event. These data confirm that recrystallised neoblastic xenotime is a useful impact geochronometer.&
Kinematic linkage between internal zone extension and shortening in more external units in the NW Alps
Publisher: Geological Society of London
Date: 05-2001
Abstract: In the Alps a major extensional shear zone unroofed eclogites in its footwall from 30 kbar to c. 10 kbar, implying of the order of 60 km of relative vertical movement in the period 45–36 Ma. The horizontal component of ergence was of the order of 100 km. We use the foreland basin sedimentary record to prove that the extension was contemporaneous with thrusting in units structurally beneath the eclogites (the Briançonnais and/or External Zones). This thrust-related convergence during that time period was of the order of 44–56 km and therefore of the same order of magnitude as internal zone ergence. Extension may have been driven by internal density contrasts. Buoyant continental crust underneath the mafic eclogites, or dense subducted slab offset from the orogen, can induce extension. Any dynamic model must account for the comparable magnitudes of extension and shortening in adjacent parts of the orogen: relative plate motions in the period 45–36 Ma played a subsidiary role.
Crystallography of refractory metal nuggets in carbonaceous chondrites: A transmission Kikuchi diffraction approach
Publisher: Elsevier BV
Date: 11-2017
Gold nuggets: supergene or hypogene?
Publisher: Informa UK Limited
Date: 10-2007
Effects of geodynamic setting on the redox state of fluids released by subducted mantle lithosphere
Publisher: Elsevier BV
Date: 04-2020
Computer vision-based framework for extracting tectonic lineaments from optical remote sensing data
Publisher: Informa UK Limited
Date: 11-10-2019
The carbonate tectonic units of northern Calabria (Italy): a record of Apulian palaeomargin evolution and Miocene convergence, continental crust subduction, and exhumation of HP–LT rocks
Publisher: Geological Society of London
Date: 15-10-2007
Shocked monazite chronometry: integrating microstructural and in situ isotopic age data for determining precise impact ages
Publisher: Springer Science and Business Media LLC
Date: 16-02-2017
Microstructural constraints on the mechanisms of the transformation to reidite in naturally shocked zircon
Publisher: Springer Science and Business Media LLC
Date: 2017
Tracing Highly Siderophile Elements through Subduction: Insights from High-pressure Serpentinites and ‘Hybrid’ Rocks from Alpine Corsica
Publisher: Oxford University Press (OUP)
Date: 02-2020
DOI: 10.1093/PETROLOGY/EGAA030
Abstract: The highly siderophile elements (HSE) include the economically critical platinum group elements (PGE Os, Ir, Ru, Rh, Pt, Pd, Au and Re), gold and rhenium. The HSE are redox sensitive in mantle and seafloor environments and have a strong affinity to iron and sulphur, therefore their distribution within the subducted mantle lithosphere record changes to oxidation state and sulphidation. The mobility of the HSE during subduction has important implications for Re–Os isotopic signatures in the mantle, and the formation of Cu–Au arc-related ore deposits. In this study, subducted rock s les from Alpine Corsica are used to track the HSE in serpentinites and hybrid ultramafic–mafic rocks through the subduction cycle. A comparison of bulk-rock HSE concentrations with those in pre-subduction analogues provides insights into the transfer of the HSE throughout the subduction cycle. Serpentinites subducted to blueschist–eclogite-facies conditions have similar HSE concentrations to primitive upper mantle (PUM) concentrations, therefore it is concluded that the HSE are not mobilized from serpentinites on the scale of the whole-rock or greater. Therefore, as suggested in previous studies, crustal lithologies may be more important contributors of the HSE to the sub-arc mantle, particularly Pt, Pd and Re. In contrast, HSE concentrations in hybrid rocks (talc schist and chlorite schist) deviate from protolith concentrations. Rhenium is higher in the talc schist, and Ir and Ru are lower in the chlorite schist than in the PUM, or possible mafic protoliths. Mineral parageneses place temporal constraints on the growth of hosts to the HSE (sulphides, oxides and metal alloys), and record changes to the activities of oxygen and sulphur (aO2–aS2), and hence redox conditions, from pre-subduction to exhumation. Laser ablation inductively coupled plasma mass spectrometry was used to determine the HSE concentrations in sulphides and oxides, and the detection of small (∼2–25 µm2) platinum group minerals utilized high-resolution SEM mapping techniques. The prograde and retrograde sulphides have lower HSE concentrations compared with sulphides from pre-subduction settings. Therefore, the redistribution of the HSE on a mineral scale from sulphides to alloys and/or other sulphides has occurred within the serpentinites, which may reflect more reducing conditions during serpentinization or subduction, consistent with the results of thermodynamic modelling. In contrast, the mineral assemblages in the hybrid rocks imply an increase in the extent of sulphidation and oxidation, and higher fluid:rock ratios during exhumation, coincident with Re enrichment in the talc schist, and a decrease in the concentrations of Ir and Ru in the chlorite schist, at length scales greater than those of the rock s les. Therefore, hybridization of lithologies at the slab–mantle interface may enhance the transfer of the HSE to the sub-arc mantle. If Re transfer from the slab to the sub-arc mantle is possible, this questions the robustness of Re–Os isotope signatures as tracers of crustal recycling.
Volcanic SiO$_\textrm2$-cristobalite: A natural product of chemical vapor deposition
Publisher: Mineralogical Society of America
Date: 04-2020
DOI: 10.2138/AM-2020-7236
Abstract: Cristobalite is a low-pressure, high-temperature SiO2 polymorph that occurs as a metastable phase in many geologic settings, including as crystals deposited from vapor within the pores of volcanic rocks. Such vapor-phase cristobalite (VPC) has been inferred to result from silica redistribution by acidic volcanic gases but a precise mechanism for its formation has not been established. We address this by investigating the composition and structure of VPC deposited on plagioclase substrates within a rhyolite lava flow, at the micrometer to nanometer scale. The VPC contains impurities of the form [AlO4/Na+]0—coupled substitution of Al3+ charge-balanced by interstitial Na+—which are typical of cristobalite. However, new electron probe microanalysis (EPMA) element maps show in idual crystals to have impurity concentrations that systematically decline from crystal cores-to-rims, and atom probe tomography reveals localized segregation of impurities to dislocations. Impurity concentrations are inversely correlated with degrees of crystallinity [observed by electron backscatter diffraction (EBSD), hyperspectral cathodoluminescence, laser Raman, and transmission electron microscopy (TEM)], such that crystal cores are poorly crystalline and rims are highly ordered tetragonal α-cristobalite. The VPC-plagioclase interfaces show evidence that dissolution-reprecipitation reactions between acidic gases and plagioclase crystals yield precursory amorphous SiO2 coatings that are suitable substrates for initial deposition of impure cristobalite. Successive layers of cubic β-cristobalite are deposited with impurity concentrations that decline as Al-bearing gases rapidly become unstable in the vapor cooling within pores. Final cooling to ambient temperature causes a displacive transformation from β→α cristobalite, but with locally expanded unit cells where impurities are abundant. We interpret this mechanism of VPC deposition to be a natural proxy for dopant-modulated Chemical Vapor Deposition, where halogen-rich acidic gases uptake silica, react with plagioclase surfaces to form suitable substrates and then deposit SiO2 as impure cristobalite. Our results have implications for volcanic hazards, as it has been established that the toxicity of crystalline silica is positively correlated with its purity. Furthermore, we note that VPC commonly goes unreported, but has been observed in silicic lavas of virtually all compositions and eruptive settings. We therefore suggest that despite being metastable at Earth's surface, cristobalite may be the most widely occurring SiO2 polymorph in extrusive volcanic rocks and a useful indicator of gas-solid reaction having occurred in cooling magma bodies.
Constraining mountain front tectonic activity in extensional setting from geomorphology and Quaternary stratigraphy: A case study from the Matese ridge, southern Apennines
Publisher: Elsevier BV
Date: 09-2019
Zircon upb geochronology and hfo isotope characteristics of granitoids from the capricorn orogen, western australia
Publisher: Oxford University Press (OUP)
Date: 30-09-2021
DOI: 10.1093/PETROLOGY/EGAB083
Abstract: The Capricorn Orogen, Western Australia, is a complex orogenic zone that records the convergence and collision of the Archaean Yilgarn and Pilbara cratons in forming the West Australian Craton (WAC), then over one billion years of subsequent intracontinental reworking. Granites associated with these tectonothermal events (the Dalgaringa, Bertibubba, Moorarie, Durlacher and Thirty Three supersuites) are exposed in the western part of the Capricorn Orogen. This study integrates radiogenic (U–Pb and Hf) and stable isotope (O) analysis of zircon grains from granitic rocks in the Capricorn Orogen to determine their ages and magmatic sources, including the relative contributions of mantle versus crustal material. Granites from the margin of the Yilgarn Craton record periods of crustal growth and reworking during the Archaean that influenced later Proterozoic magmatic events. Components of the Capricorn Orogen, collectively termed the Glenburgh Terrane, have previously been considered to be exotic to the adjacent Pilbara and Yilgarn cratons. However, new U–Pb zircon geochronology and Lu–Hf isotope compositions of basement rocks in the Glenburgh Terrane (the Halfway Gneiss) have similarities to some terranes of the Yilgarn Craton, and are interpreted to represent a reworked portion of the craton that was re-accreted during the Glenburgh Orogeny. Arc magmatism during the Ma Glenburgh Orogeny resulted in a period of crustal growth, with magmas representing a mixture of 50–90 % mantle-derived magmas and 50–10 % magmas derived from an evolved crustal component with an isotopic composition equivalent to that of the Halfway Gneiss. Following assembly of the WAC, granite magmatism in the Capricorn Orogen records a significant change from one dominated by mantle-derived magmatism to one dominated by crustal melting and an increased contribution from metasedimentary material. This transition reflects a geodynamic evolution from subduction–accretion to collision and intracratonic reworking. The isotopic characteristics of granites from the Moorarie Supersuite indicate three distinct sources: (1) a metasedimentary component (2) an evolved crustal component, comparable with the Glenburgh Terrane (3) a mafic juvenile component. Following this, the Hf–O compositions of the Durlacher Supersuite indicate that they were derived from reworking of the Moorarie Supersuite granites, and require no juvenile contribution or any additional sedimentary source. The isotopic compositions of the Thirty Three Supersuite pegmatites indicate that they were largely derived from reworking of the Moorarie and Durlacher supersuites.
Nanoscale Isotopic Dating of Monazite
Publisher: Wiley
Date: 27-07-2020
DOI: 10.1111/GGR.12340
Empirical constraints on shock features in monazite using shocked zircon inclusions
Publisher: Geological Society of America
Date: 08-07-2016
DOI: 10.1130/G37979.1
Antimony in rutile as a pathfinder for orogenic gold deposits
Publisher: Elsevier BV
Date: 03-2019
Mantle deformation during rifting: Constraints from quantitative microstructural analysis of olivine from the East African Rift (Marsabit, Kenya)
Publisher: Elsevier BV
Date: 11-2013
Lunar samples record an impact 4.2 billion years ago that may have formed the Serenitatis Basin
Publisher: Springer Science and Business Media LLC
Date: 09-06-2021
DOI: 10.1038/S43247-021-00181-Z
Abstract: Impact cratering on the Moon and the derived size-frequency distribution functions of lunar impact craters are used to determine the ages of uns led planetary surfaces across the Solar System. Radiometric dating of lunar s les provides an absolute age baseline, however, crater-chronology functions for the Moon remain poorly constrained for ages beyond 3.9 billion years. Here we present U–Pb geochronology of phosphate minerals within shocked lunar norites of a boulder from the Apollo 17 Station 8. These minerals record an older impact event around 4.2 billion years ago, and a younger disturbance at around 0.5 billion years ago. Based on nanoscale observations using atom probe tomography, lunar cratering records, and impact simulations, we ascribe the older event to the formation of the large Serenitatis Basin and the younger possibly to that of the Dawes crater. This suggests the Serenitatis Basin formed unrelated to or in the early stages of a protracted Late Heavy Bombardment.
Extreme plastic deformation and subsequent Pb loss in shocked xenotime from the Vredefort Dome, South Africa
Publisher: Geological Society of America
Date: 02-08-2021
Abstract: Accessory mineral U-Pb geochronometers are crucial tools for constraining the timing of deformation in a wide range of geological settings. Despite the growing recognition that intragrain age variations within deformed minerals can spatially correlate to zones of microstructural damage, the causal mechanisms of Pb loss are not always evident. Here, we report the first U-Pb data for shock-deformed xenotime, from a detrital grain collected at the Vredefort impact structure in South Africa. Orientation mapping revealed multiple shock features, including pervasive planar deformation bands (PDBs) that accommodate up to 40° of lattice misorientation by & & {010} slip, and also an ~50-µm-wide intragrain shear zone that contains {112} deformation twin lamellae in two orientations. Twenty-nine in situ secondary ion mass spectrometry (SIMS) U-Pb analyses from all microstructural domains yielded a well-defined discordia with upper-intercept age of 2953 ± 15 Ma (mean square of weighted deviates [MSWD] = 0.57, n = 29, 2σ), consistent with derivation from Kaapvaal craton bedrock. However, the 1754 ± 150 Ma lower concordia intercept age falls between the 2020 Ma Vredefort impact and ca. 1100 Ma Kibaran orogenesis and is not well explained by multiple Pb-loss episodes. The pattern and degree of Pb loss (discordance) correlate with increased [U] but do not correlate to microstructure (twin, PDB) or to crystallinity (band contrast) at the scale of SIMS analysis. Numerical modeling of the Pb-loss history using a concordia-discordia-comparison (CDC) test indicated that the lower concordia age is instead best explained by an alteration episode at ca. 1750 Ma, rather than a multiple Pb-loss history. In this ex le, the U-Pb system in deformed xenotime does not record a clear signature of impact age resetting rather, the implied high dislocation density recorded by planar deformation bands and the presence of deformation twins facilitated subsequent Pb loss during a younger event that affected the Witwatersrand basin. Microstructural characterization of xenotime targeted for geochronology provides a new tool for recognizing evidence of deformation and can provide insight into complex age data from highly strained grains, and, as is the case in this study, elucidate previously unrecognized alteration events.
Evolution of zircon deformation mechanisms in a shear zone (Lanzo massif, Western-Alps)
Publisher: Elsevier BV
Date: 12-2011
Standardizing Spatial Reconstruction Parameters for the Atom Probe Analysis of Common Minerals
Publisher: Oxford University Press (OUP)
Date: 08-2022
DOI: 10.1017/S1431927621013714
Abstract: Well-defined reconstruction parameters are essential to quantify the size, shape, and distribution of nanoscale features in atom probe tomography (APT) datasets. However, the reconstruction parameters of many minerals are difficult to estimate because intrinsic spatial markers, such as crystallographic planes, are not usually present within the datasets themselves. Using transmission and/or scanning electron microscopy imaging of needle-shaped specimens before and after atom probe analysis, we test various approaches to provide best-fit reconstruction parameters for voltage-based APT reconstructions. The results demonstrate that the length measurement of evaporated material, constrained by overlaying pre- and post-analysis images, yields more consistent reconstruction parameters than the measurement of final tip radius. Using this approach, we provide standardized parameters that may be used in APT reconstructions of 11 minerals. The adoption of standardized reconstruction parameters by the geoscience APT community will alleviate potential problems in the measurement of nanoscale features (e.g., clusters and interfaces) caused by the use of inappropriate parameters.
The two-component regulator WalKR provides an essential link between cell wall homeostasis with DNA replication inStaphylococcus aureus
Publisher: Cold Spring Harbor Laboratory
Date: 28-02-2023
DOI: 10.1101/2023.02.27.530350
Abstract: Among the 16 two-component systems (TCSs) in the opportunistic human pathogen Staphylococcus aureus , only WalKR is essential. Like orthologous systems in other Bacillota, S. aureus WalKR controls autolysins involved in peptidoglycan remodelling and is therefore intimately involved in cell ision. However, despite the importance of WalKR in S. aureus , the basis for its essentiality is not understood and the regulon poorly defined. Here, we defined a consensus WalR DNA-binding motif and the direct WalKR regulon by using functional genomics, including ChIP-seq, with a panel of isogenic walKR mutants that had a spectrum of altered activities. Consistent with prior findings, the direct regulon includes multiple autolysin genes. However, this work also revealed that WalR directly regulates at least five essential genes involved in lipoteichoic acid synthesis ( ltaS ) translation (rplK ) DNA compaction ( hup ) initiation of DNA replication ( dnaA, hup ) and purine nucleotide metabolism ( prs ). Thus, WalKR in S. aureus serves as a polyfunctional regulator that contributes to fundamental control over critical cell processes by co-ordinately linking cell wall homeostasis with purine biosynthesis, protein biosynthesis, and DNA replication. Collectively, our findings address the essentiality of this locus and highlight the importance of WalKR as a bona fide target for novel anti-staphylococcal therapeutics.
Quantitative microstructural characterization of natrojarosite scale formed during high-pressure acid leaching of lateritic nickel ore
Publisher: Mineralogical Society of America
Date: 08-2009
DOI: 10.2138/AM.2009.3104
Zircon U–Pb strain chronometry reveals deep impact-triggered flow
Publisher: Elsevier BV
Date: 2009
A new kind of invisible gold in pyrite hosted in deformation-related dislocations
Publisher: Geological Society of America
Date: 24-06-2021
DOI: 10.1130/G49028.1
Abstract: Mining of “invisible gold” associated with sulfides in gold ores represents a significant proportion of gold production worldwide. Gold hosted in sulfide minerals has been proposed to be structurally bound in the crystal lattice as a sulfide-gold alloy and/or to occur as discrete metallic nanoparticles. Using a combination of microstructural quantification and nanoscale geochemical analyses on a pyrite crystal from an orogenic gold deposit, we show that dislocations hosted in a deformation low-angle boundary can be enriched in Ni, Cu, As, Pb, Sb, Bi, and Au. The cumulative trace-element enrichment in the dislocations is 3.2 at% higher compared to the bulk crystal. We propose that trace elements were segregated during the migration of the dislocation following the dislocation-impurity pair model. The gold hosted in nanoscale dislocations represents a new style of invisible gold.
A scanning ion imaging investigation into the micron-scale U-Pb systematics in a complex lunar zircon
Publisher: Elsevier BV
Date: 11-2016
Earth's oldest mantle fabrics indicate Eoarchaean subduction
Publisher: Springer Science and Business Media LLC
Date: 16-02-2016
DOI: 10.1038/NCOMMS10665
Abstract: The extension of subduction processes into the Eoarchaean era (4.0–3.6 Ga) is controversial. The oldest reported terrestrial olivine, from two dunite lenses within the ∼3,720 Ma Isua supracrustal belt in Greenland, record a shape-preferred orientation of olivine crystals defining a weak foliation and a well-defined lattice-preferred orientation (LPO). [001] parallel to the maximum finite elongation direction and (010) perpendicular to the foliation plane define a B-type LPO. In the modern Earth such fabrics are associated with deformation of mantle rocks in the hanging wall of subduction systems an interpretation supported by experiments. Here we show that the presence of B-type fabrics in the studied Isua dunites is consistent with a mantle origin and a supra-subduction mantle wedge setting, the latter supported by compositional data from nearby mafic rocks. Our results provide independent microstructural data consistent with the operation of Eoarchaean subduction and indicate that microstructural analyses of ancient ultramafic rocks provide a valuable record of Archaean geodynamics.
Morphology and microstructure of chromite crystals in chromitites from the Merensky Reef (Bushveld Complex, South Africa)
Publisher: Springer Science and Business Media LLC
Date: 29-12-2013
An atmospheric source of S in Mesoarchaean structurally-controlled gold mineralisation of the Barberton Greenstone Belt
Publisher: Elsevier BV
Date: 10-2016
Novel Applications of FIB-SEM-Based ToF-SIMS in Atom Probe Tomography Workflows
Publisher: Oxford University Press (OUP)
Date: 09-03-2020
DOI: 10.1017/S1431927620000136
Abstract: Atom probe tomography (APT) is used to quantify atomic-scale elemental and isotopic compositional variations within a very small volume of material (typically .01 µ m 3 ). The small analytical volume ideally contains specific compositional or microstructural targets that can be placed within the context of the previously characterized surface in order to facilitate a correct interpretation of APT data. In this regard, careful targeting and preparation are paramount to ensure that the desired target, which is often smaller than 100 nm, is optimally located within the APT specimen. Needle-shaped specimens required for atom probe analysis are commonly prepared using a focused ion beam scanning electron microscope (FIB-SEM). Here, we utilize FIB-SEM-based time-of-flight secondary ion mass spectrometry (ToF-SIMS) to illustrate a novel approach to targeting nm compositional and isotopic variations that can be used for targeting regions of interest for subsequent lift-out and APT analysis. We present a new method for high-spatial resolution targeting of small features that involves using FIB-SEM-based electron deposition of platinum “buttons” prior to standard lift-out and sharpening procedures for atom probe specimen manufacture. In combination, FIB-ToF-SIMS analysis and application of the “button” method ensure that even the smallest APT targets can be successfully captured in extracted needles.
Naturally Occurring Gold Nanoparticles and Nanoplates
Publisher: Geological Society of America
Date: 2008
DOI: 10.1130/G24749A.1
Geochronology of Paleoproterozoic Augen Gneisses in the Western Gneiss Region, Norway: Evidence for Sveconorwegian Zircon Neocrystallization and Caledonian Zircon Deformation
Publisher: University of Chicago Press
Date: 03-2013
DOI: 10.1086/669229
Grampian migmatites in the Buchan Block, NE Scotland
Publisher: Wiley
Date: 20-07-2015
DOI: 10.1111/JMG.12147
Temporal constraints on Palaeoproterozoic eclogite formation and exhumation (Usagaran Orogen, Tanzania)
Publisher: Elsevier BV
Date: 07-2004
Complex high-strain deformation in the Usagaran Orogen, Tanzania: structural setting of Palaeoproterozoic eclogites
Publisher: Elsevier BV
Date: 11-2003
Microstructural evolution and trace element mobility in Witwatersrand pyrite
Publisher: Springer Science and Business Media LLC
Date: 24-07-2013
Micro- and nano-scale textural and compositional zonation in plagioclase at the Black Mountain porphyry Cu deposit: Implications for magmatic processes
Publisher: Mineralogical Society of America
Date: 03-2019
DOI: 10.2138/AM-2019-6609
Zircon geochronology reveals polyphase magmatism and crustal anatexis in the Buchan Block, NE Scotland: Implications for the Grampian Orogeny
Publisher: Elsevier BV
Date: 11-2017
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