Denis Fougerouse

• PhD
• Senior Research Fellow at Curtin University

Understanding elements uptake and release from minerals in source rocks is crucial for comprehending critical metals accumulation, yet the mechanisms and kinetics of element mobilization at the atomic scale remain mostly unknown. Here, we analyzed the distribution of cobalt (Co) in natural pyrite from a Cu-Co ore deposit and found that metals distr...

In natural corundum, a strong geochemical correlation is sometimes observed between Be and heavy high field strength elements (HHFSEs) such as Nb, Ta and W, and it has been hypothesized that trace elements are hosted in primary inclusions. However, no known mineral enriched in both Be and HHFSEs stable at these geological conditions can explain thi...

Atom probe tomography (APT) of ²³⁸U and ²⁰⁶Pb has been applied to baddeleyite crystals from the Hart Dolerite (1791±1 Ma) and the Great Dyke of Mauritania (2732±2 Ma) in an effort to constrain the average nuclear recoil distance of ²³⁸U series daughter nuclei and correct alpha-recoil-induced Pb loss on U–Pb ages from small baddeleyite crystals. The...

Finding direct evidence for hydrous fluids on early Mars is of interest for understanding the origin of water on rocky planets, surface processes, and conditions essential for habitability, but it is challenging to obtain from martian meteorites. Micro- to nanoscale microscopy of a unique impact-shocked zircon from the regolith breccia meteorite NW...

The causes of U-Pb isotopic discordance documented by Paquette et al. (2004) in monazite grains from the ultra-high temperature (UHT) granulite of the Andriamena unit of Madagascar are re-evaluated in the light of nanoscale crystal-chemical characterization utilising Atom Probe Tomography (APT) and state-of-the-art Scanning Transmission Electron Mi...

Understanding the complex interplay between the processes of mineral crystallization and the incorporation of trace elements, particularly in economically significant deposits like Carlin-type gold systems, is essential for unraveling geological processes. This study investigates the microscale to nanoscale texture and composition of weakly deforme...

The mechanisms responsible for invisible gold enrichment driven by coupled dissolution-reprecipitation reaction (CDR) are debated. Here we report the micro- to nano-scale textures of arsenian pyrite in a high-grade (>10 g/t) gold ore from the Chang’an deposit to trace the gold enrichment process. Our study records a CDR-driven evolution of mineral...

Atom probe tomography (APT) of 238U and 206Pb has been applied to baddeleyite crystals from the Hart Dolerite (1791 ± 1 Ma) and the Great Dyke of Mauritania (2732 ± 2 Ma) in an effort to map U and Pb concentration at the nanometre scale. The purpose was to constrain the average nuclear recoil distance of 238U-series daughter nuclei in order to corr...

Accessory minerals like zircon, rutile and monazite are routinely studied to inform about the timing and nature of geological processes. These studies are underpinned by our understanding of the transfer processes of trace elements and the assumption that the isotopic systems remain undisturbed. However, the presence of microstructures or Pb-bearin...

The mineral zircon is used widely to constrain the age of rocks and the processes that formed them. Although zircon is robust to a range of physical and chemical processes, it may show evidence for rapid re-equilibration that is generally considered to reflect interaction with hydrous fluids. Here, we show that zircon grains that crystallized from...

Samples returned from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 mission revealed that Ryugu is composed of materials consistent with CI chondrites and some types of space weathering. We report detailed mineralogy of the fine‐grained Ryugu samples allocated to our “Sand” team and report additional space weathering features found on t...

Argyle is the world’s largest source of natural diamonds, yet one of only a few economic deposits hosted in a Paleoproterozoic orogen. The geodynamic triggers responsible for its alkaline ultramafic volcanic host are unknown. Here we show, using U-Pb and (U-Th)/He geochronology of detrital apatite and detrital zircon, and U-Pb dating of hydrotherma...

Atom probe tomography of 238U and 206Pb has been applied to baddeleyite crystals from the Hart Dolerite (1791 ± 1 Ma) and the Great Dyke of Mauritania (2732 ± 2 Ma) in an effort to constrain the average nuclear recoil distance of U-series daughter nuclei and thereby correct U-Pb ages determined on small baddeleyite crystals for alpha-recoil loss of...

Ore minerals provide important insights into the complex interplay of magmatic, tectonic and hydrothermal processes that lead to the formation of mineral deposits. Besides their main economic constituents, ore minerals also contain trace elements that are valuable for modeling the space-time evolution of a mineralizing system, for dating ore minera...

Constraining the age of many types of ore deposits remains challenging due to the lack of radiogenic isotopes incorporated into common ore-forming minerals. The timing of pre-Caledonian-hosted Cu mineralization along the entire ∼1200 km-long East Greenland Caledonides remains virtually unknown, hampering our knowledge of ore deposit timing and gene...

Understanding radionuclides mass transfer mechanisms in monazite (LREEPO4) and the resulting features, from the micro- to the nanoscale, is critical to its use as a robust U–Th–Pb geochronometer. A detailed multiscale characterisation of discordant monazite grains from a granulite which records a polymetamorphic history explores the mechanisms of T...

Constraining precise ages for impact events is crucial in establishing Earth’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 imp...

This study focuses on the low-temperature mineralogical response of xenotime, a phosphate mineral routinely used as a geochronometer, to fluid-assisted alteration. The studied xenotime grain (z6413) comes from a ~1000 Ma pegmatite from the Grenville Province, Canada, and is commonly used as reference material for U-Pb analyses. At the microscale, t...

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 asteroid...

Tellurium (Te) is a critical commodity, essential for renewable energies and high-tech applications. Most Te is currently recovered from copper smelters, but rising demand requires sourcing from alternative supplies. However, the mineralogy of Te-rich ores is poorly understood and hinders their economic potential. Here, we investigate the distribut...

Chemical heterogeneities along grain boundaries in garnet occur across a wide range of metamorphic conditions, yet the processes underlying their development remain poorly understood. Here we integrate electron backscattered diffraction (EBSD) and atom probe tomography (APT) to evaluate the mechanisms driving nanoscale trace element mobility to def...

The emplacement of large igneous provinces (LIPs) has been linked to catastrophic mass extinctions in Earth’s history, but some LIPs are only associated with less severe oceanic anoxic events, and others have negligible environmental effects. Although it is widely accepted that massive magma outpouring can affect the environment through volatile de...

Economic gold deposits result from a 100- to 10,000-fold enrichment in gold relative to crustal background. In hydrothermal systems, this enrichment is achieved through the transport and accumulation of metals via deeply sourced fluids to a site of deposition. However, the generally low metal solubility of Au in aqueous solutions in orogenic system...

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

Complex microstructures of pyrite induced by superimposed deformation and fluid infiltration in lode gold deposits can record time-integrated physicochemical changes of ore-forming fluids. This study used a combination of techniques (EBSD, μ-XRF, EMPA, APT, and TEM) to characterize and decode the microstructures of pyrite in an optically homogeneou...

The discordance of U–Th–Pb isotopic systems in geochronometers, and how such data are interpreted, are still major issues in the geosciences. To better understand the disturbance of isotopic systems, and how this impacts the derivation of geologically-meaningful ages, previously studied discordant monazite from the ultrahigh temperature paragneiss...

To understand the controls of basin paleogeographic evolution on sediment-hosted gold metallogenesis, a study was undertaken of pyrite texture and geochemistry of the Jinya, Nakuang, and Gaolong gold deposits in the Youjiang Basin, SW China. Syn-sedimentary/diagenetic pyrite and three generations of hydrothermal pyrite (As-Au-poor core, anomalously...

The southern part of the West African Craton includes the Baoulé-Mossi Domain, the world’s premier Paleoproterozoic gold province (~10,000 metric ton gold endowment). Structural, metamorphic, and geochronological data suggest gold mineralisation occurred during three episodes that span much of the Eoeburnean and Eburnean orogenic cycles. Eoeburnean...

Element mobility is a critical component in all geological processes and understanding the mechanisms responsible for element mobility in minerals is a fundamental requirement for many geochemical and geochronological applications. Volume diffusion of elements is a commonly assumed process. However, linear defects (dislocations) are an essential co...

The isotopic composition of water in Earth’s oceans is challenging to recreate using a plausible mixture of known extraterrestrial sources such as asteroids—an additional isotopically light reservoir is required. The Sun’s solar wind could provide an answer to balance Earth’s water budget. We used atom probe tomography to directly observe an averag...

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 dat...

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 zirc...

Glassy melt inclusions are unique geological repositories that preserve evidence of the formation and evolution of mantle and crustal-derived magmas. However, the mechanisms responsible for their preservation in slowly cooled crustal rocks remain contentious, in some part due to their small size (commonly < 10 µm) and the technical difficulty in qu...

To test the potential of deformation twins to record the age of impact events, micrometre-scale size mechanical twins in shocked monazite grains from three impact structures were analyzed by atom probe tomography (APT). Shocked monazite from Vredefort (South Africa; ∼300 km crater diameter), Araguainha (Brazil; ∼40 km diameter), and Woodleigh (Aust...

The geometry and composition of deformation-related low-angle boundaries in naturally deformed olivine were characterized by electron backscattered diffraction (EBSD) and atom probe tomography (APT). EBSD data show the presence of discrete low-angle tilt boundaries, which formed by subgrain rotation recrystallisation associated with the (100)[001]...

A 10- to 10 000-fold enrichment is required to form economic metal deposits. Such enrichment is achieved through the accumulation of metals transported in hydrothermal fluids from their source to the deposit. The contribution of gold nanoparticle suspensions in fluids is required to form bonanza gold grades. However, as the source of gold is spatia...

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 quanti...

Impact cratering on the Moon and the derived size-frequency distribution functions of lunar impact craters are used to determine the ages of unsampled planetary surfaces across the Solar System. Radiometric dating of lunar samples provides an absolute age baseline, however , crater-chronology functions for the Moon remain poorly constrained for age...

Xenotime (YPO4) 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 nano‐scale analysis. In this study, we develop a...

Gold (Au) is largely hosted by pyrite in a variety of hydrothermal systems, but the incorporation of Au into pyrite under disequilibrium conditions remains poorly understood. We integrate synchrotron X-ray fluorescence microscopy, electron backscatter diffraction, nanoscale secondary ion mass spectrometry, and laser ablation–multicollector–inductiv...

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 destru...

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), tran...

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-abl...

Monazite U‐Th‐Pb geochronology is widely used for dating geological processes, but current analytical techniques are limited to grains greater than 5 μm in diameter. This limitation precludes the analysis of both micrometre‐scale discrete monazite grains and fine textures within monazite crystals that are commonly found. Here, we analyse reference...

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 it...

Atom probe tomography (APT) is used to quantify atomic-scale elemental and isotopic compositional variations within a very small volume of material (typically <0.01 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...

Carbonaceous matter (CM) plays a critical role in the formation of sediment-hosted ore deposits, but metal partitioning between CM and associated sulfides remains unclear. Here we use synchrotron X-ray fluorescence microscopy (SXRF), laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS), and nanoscale secondary ion mass spectromet...

Vertebrate fossils embedded in amber represent a particularly valuable paleobiological record as amber is supposed to be a barrier to the environment, precluding significant alteration of the animals’ body over geological time. The mode and processes of amber preservation are still under debate, and it is questionable to what extent original materi...

Atom probe tomography is an analytical technique that provides quantitative three‐dimensional elemental and isotopic analyses at sub‐nanometre resolution across the whole periodic table. Although developed and mostly used in the materials science and semiconductor fields, recent years have seen increasing development and application in the geoscien...

Unravelling complex microbial activity in modern hydrothermal vents can provide crucial insights into the evolution of ancient life on Earth. It is well established that microorganisms in hydrothermal vents have a significant impact on the cycling of metals and mineral formation. However, the detailed roles played by microorganisms in driving sulfi...

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/...

Goethite (α-FeOOH) is dispersed throughout 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 co-exists with aqueous Fe(II) (Fe(II)aq), which accelerates recrystallization by coupled...

Several examples of zircon grains from high- to ultrahigh-pressure (UHP) and ultrahigh-temperature (UHT) metapelites exhibit a characteristic, yet atypical, core–rim interface domain < 5-μm wide observed in cathodoluminescence (CL) imaging. The interface domain is located immediately against the magmatic core and is comprised of an irregular, 0–2-μ...

Spatial Reconstruction of Atom Probe Data from Zircon - Volume 25 Supplement - D.W. Saxey, D. Fougerouse, W.D.A. Rickard, S.M. Reddy

Chemical zoning in minerals records fluid-rock interaction and crystal growth kinetics via texturally complex features, the genesis of which remains a subject of debate. Here, we combined nanoscale secondary ion mass spectrometry (NanoSIMS) and atom probe tomography to better characterize trace-element zoning in a gold (Au)–rich pyrite crystal from...

The West Qinling Orogen is endowed with more than 100 sediment-hosted gold deposits with an estimated resource of > 2000 t Au. Previous radiometric dating results have shown that most deposits formed during a Late Triassic to Early Jurassic period of contractional deformation over the orogen. However, here we show that the newly discovered Daqiao g...

In a hypervelocity impact event, the temperatures and pressures generated by the shock waves far exceed the values produced by endogenic processes. The shock-induced processes can modify the distribution of trace elements in zircon grains located in target rocks, potentially affecting the geochemical reliability of zircon, but also providing an opp...

In our study we explore the applicability of rutile as a pathfinder for orogenic gold deposits, which are an important source of this metal worldwide. We analysed rutile associated with orogenic Au deposits from three different Precambrian terranes, the Capricorn Orogen, the Barberton Greenstone Belt and the Ashanti Belt, all of which formed under...

Textural and compositional microscale (10-100 μm) and nanoscale (10-100 nm) zoning in a plagioclase phenocryst from a fresh, syn-mineralization diorite porphyry (Black Mountain porphyry Cu-Au deposit, Philippines) was characterized for major and trace elements using electron microprobe, laser ablation-inductively coupled plasma-mass spectrometry, a...

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 materia...

Understanding the mechanisms of parent-daughter isotopic mobility at the nanoscale is key to rigorous interpretation of U–Th–Pb data and associated dating. Until now, all nanoscale geochronological studies on geological samples have relied on either Transmission Electron Microscope (TEM) or Atom Probe Microscopy (APM) characterizations alone, thus...

Mineral-scale episodic replacement of auriferous pyrite by texturally-complex pyrite, marcasite and minor arsenopyrite occurred in breccia ores from the Daqiao epizonal orogenic gold deposit, West Qinling Orogen, China. This study uses a novel combination of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), Nanoscale secondar...

The West Qinling Orogen (WQO) in Central China Orogenic Belt contains numerous metasedimentary rock-hosted gold deposits (>2000 t Au), which mainly formed during two pulses: one previously recognized in the Late Triassic to Early Jurassic (T3eJ1) and one only recently identified in the Late Jurassic to Early Cretaceous (J3eK1). Few studies have foc...

The West Qinling Orogen (WQO) in Central China Orogenic Belt contains numerous metasedimentary rock-hosted gold deposits (>2000 t Au), which mainly formed during two pulses: one previously recognized in the Late Triassic to Early Jurassic (T3–J1) and one only recently identified in the Late Jurassic to Early Cretaceous (J3–K1). Few studies have foc...

In recent years, atom probe tomography (APT) has been increasingly used to study minerals, and in particular the mineral zircon. Zircon (ZrSiO4) is ideally suited for geochronology by utilising the U-Th-Pb isotope systems, and trace element compositions are also widely used to constrain petrogenetic processes. However, while standard geoanalytical...

Atom probe microscopy (APM) is a relatively new in situ tool for measuring isotope fractions from nanoscale volumes (< 0.01 μm³). We calculate the theoretical detectable difference of an isotope ratio measurement result from APM using counting statistics of a hypothetical dataset to be ± 4δ or 0.4% (2s). However, challenges associated with APM meas...

The Pb isotopic composition of rocks is widely used to constrain the sources and mobility of melts and hydrothermal fluids in the Earth's crust. In many cases, the Pb isotopic composition appears to represent mixing of multiple Pb reservoirs. However, the nature, scale and mechanisms responsible for isotopic mixing are not well known. Additionally,...

Common Pb, the portion of non-radiogenic Pb within a U bearing mineral, needs to be accurately accounted for in order to subtract its effect on U-Pb isotopic ratios so that meaningful ages can be calculated. The propensity to accommodate common Pb during crystallization, or later, is different across the range of U bearing minerals used for geochro...

The widespread use of monazite (LREEPO4) in U-Pb geochronology is underpinned by the assumption that it incorporates negligible amounts of Pb during initial growth, and that radiogenic Pb remains immobile after formation. We have investigated the nanoscale distribution of Pb in monazite from granulite facies rocks of the Sandmata Metamorphic Comple...