Luc-Serge Doucet

Curtin University · The Institute for Geoscience Research (TIGeR)

The Earth’s mantle is divided by the circum-Pacific subduction girdle into the African and Pacific domains, each featuring a large low-shear-wave-velocity province (LLSVP) in the lower mantle. However, how this hemispherical-scale mantle structure links to Earth’s plate tectonic evolution remains unclear. Previous geochemical work has suggested the...

Plate tectonics drives the compositional diversity of Earth’s convecting mantle through subduction of lithosphere. In this context, the role of evolving global geodynamics and plate (re)organization on the spatial and temporal distribution of compositional heterogeneities in the convecting mantle is poorly understood. Here, using the geochemical co...

Earth’s mantle isotopic composition is highly heterogeneous, with enriched and depleted regions1–3 shaped by a complex history of depletion and re-enrichment over 4.5 billion years. The spatial configuration of large-scale heterogeneity in the mantle is not random4,5, but the timing and mechanisms that caused such heterogeneity are still debated2,6...

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...

Technological progress and the rapid increase in geochemical data often create bottlenecks in many studies , because current methods are designed using limited number of data and cannot handle large data-sets. In geoscience, tectonic discrimination illustrates this issue, using geochemical analyses to define tectonic settings when most of the geolo...

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...

Keywords: UHT metamorphism partial melting crustal differentiation granulite zircon Variscan orogeny Lower crustal ultra-high temperature (UHT) metamorphism and the resulting production and transfer of granitic magmas represent key processes of intracrustal differentiation. The timescales of these phenomena are debated, due to the complexity of the...

The present-day mantle is divided into the African and Pacific domains by the circum-Pacific subduction girdle. Very little is known about the mantle composition of the Pacific Domain before 120 Ma due to the scarcity of the oceanic record, having mostly been destroyed by subduction processes. Accreted oceanic lithosphere (ophiolites) in orogens al...

Highly siderophile elements (HSEs), including Re and Os, are used extensively as geochemical tracers and geochronometers to investigate the formation and evolution of Earth’s crust and mantle. Mantle rocks are commonly serpentinized, but the effect of serpentinization on the distribution of HSEs is controversial because HSEs are commonly hosted by...

The tectonic evolution of the Neoproterozoic Arabian-Nubian Shield (ANS) is widely held as an example of crustal growth processes. The ANS consists of continental crust formed prior to and during the collision between East and West Gondwana. In this contribution, we compile, review, and synthesize published whole-rock Nd-Sr isotopic and zircon U-Pb...

Basalts are ubiquitous, mantle-derived mafic rocks found within all tectonic settings. Studying the chemical composition of basalts has proven to be an effective way to understand tectonics-related mantle processes for more recent periods of Earth history when other geological and tectonic records are still well preserved. However, using basalt geo...

Tonalite-trondhjemite-granodiorite (TTG) rocks consitute the dominant felsic lithology of the Archean crust in most cratons, but their petrogenesis and geodynamic setting are still matters of great debate. Here, we report new Fe isotopic analyses for ca. 2.5 Ga diorites and TTGs with compositions typically interpreted to reflect a high-pressure aff...

The formation and differentiation of the crust of Mars in the first tens of millions of years after its accretion can only be deciphered from incredibly limited records. The martian breccia NWA 7034 and its paired stones is one of them. This meteorite contains the oldest martian igneous material ever dated: ~4.5 Ga old. However, its source and geol...

Improvements in analytical techniques over the past decades have led to an exponential growth of scientific data. The EarthChem Portal is the most comprehensive and popular open access online database in Earth sciences. This portal “operates a suite of data systems that assist geoscientists with accessing, sharing, and using geochemical, petrologic...

Improvements in analytical techniques over the past decades have led to an exponential growth of scientific data. The EarthChem Portal is the most comprehensive and popular open access online database in Earth sciences. This portal “operates a suite of data systems that assist geoscientists with accessing, sharing, and using geochemical, petrologic...

The impact flux over the last 3 Ga in the inner Solar System is commonly assumed to be constant through time due to insufficient data to warrant a different choice for this range of time. However, asteroid break-up events in the main belt may have been responsible for cratering spikes over the last ∼2 Ga on the Earth-Moon system. Due to its proximi...

The impact flux over the last 3 Ga in the inner Solar System is commonly assumed to be constant through time. However, asteroid break-up events in the main belt may have been responsible for cratering spikes over the last ~2 Ga on the Earth-Moon system. We investigate here the possible variations of the size frequency distributions of impactors fro...

The only martian rock samples on Earth are meteorites ejected from the surface of Mars by asteroid impacts. The locations and geological contexts of the launch sites are currently unknown. Determining the impact locations is essential to unravel the relations between the evolution of the martian interior and its surface. Here we adapt a Crater Dete...

Rare oceanic diamonds are believed to have a mantle transition zone origin like super-deep continental diamonds. However, oceanic diamonds have a homogeneous and organic-like light carbon isotope signature (δ13C − 28 to − 20‰) instead of the extremely variable organic to lithospheric mantle signature of super-deep continental diamonds (δ13C − 25‰ t...

The growth of continental crust through melt extraction from the mantle is a critical component of the chemical evolution of the Earth and the development of plate tectonics. However, the mechanisms involved remain debated. Here, we conduct petrological and geochemical analyses on a large (up to 5000 km 2) granitoid body in the Arabian-Nubian shiel...

Island-arc accretion during the assembly of Gondwana has been widely regarded as the main mechanism for Neoproterozoic crustal growth in the Arabian-Nubian Shield (ANS). However, processes involved to transform the newly accreted juvenile terranes into a typical continental crust remain unclear. Here, we present geochemical, isotopic, and U-Pb geoc...

An emerging consensus suggests that large igneous provinces (LIPs) are a significant driver of dramatic global environmental and biological changes, including several Phanerozoic mass extinctions, leading to plausible links with geological time scale (GTS) boundaries. LIP- induced environmental changes are now being identified in the Precambrian re...

The Archean continental lithosphere consists of a dominantly felsic continental crust, made of tonalite-trondhjemite-granodiorite (TTG) and subordinate granitoids, and a cratonic lithospheric mantle, made of highly refractory peridotites. Whether they stemmed from the same process of differentiation from the primitive mantle, or were two distinct c...

The status of Pannotia as an Ediacaran supercontinent, or even its mere existence as a coherent large landmass, is controversial. The effect of its hypothesized amalgamation is generally ignored in mantle convection models claiming the transition from Rodinia to Pangaea represents a single supercontinent cycle. We apply three geodynamic scenarios t...

The Earth’s mantle is currently divided into the African and Pacific domains, separated by the circum-Pacific subduction girdle, and each domain features a large low shear-wave velocity province (LLSVP) in the lower mantle. However, it remains controversial as to whether the LLSVPs have been stationary through time or dynamic, changing in response...

Nickel stable isotope ratios have attracted a growing interest across the (bio)geochemical and environmental sciences since the late 2000s. Accuracy and precision of Multi-Collector Inductively Coupled-Plasma Mass Spectrometry (MC-ICP-MS) measurements depend crucially on efficient chemical purification of the target analyte to avoid spectral and no...

Progressive mantle melting during the Earth's earliest evolution led to the formation of a depleted mantle and a continental crust enriched in highly incompatible elements. Re-enrichment of Earth's mantle can occur when continental crustal materials begin to founder into the mantle by either subduction or, to a lesser degree, by delamination proces...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Water and iron are believed to be key constituents controlling the strength and density of the lithosphere and, therefore, play a crucial role in the long-term stability of cratons. On the other hand, metasomatism can modify the water and iron abundances in the mantle and possibly triggers thermo-mechanical erosion of cratonic keels. Whether local...

Subduction at convergent margins introduces a range of sedimentary and crustal materials into the mantle, providing the most dominant form of heterogeneity in the source of oceanic basalts. Yet, the relationship between geochemical variability and lithologic heterogeneities in the Earth's mantle remains controversial. In this paper, we comprehensiv...

The most dominant features in the present-day lower mantle are the two antipodal African and Pacific large low-shear-velocity provinces (LLSVPs). How and when these two structures formed, and whether they are fixed and long lived through Earth history or dynamic and linked to the supercontinent cycles, remain first-order geodynamic questions. Hotsp...

Plate tectonics and mantle plumes are two of the most fundamental solid-Earth processes that have operated through much of Earth history. For the past 300 million years, mantle plumes are known to derive mostly from two large low shear velocity provinces (LLSVPs) above the core-mantle boundary, referred to as the African and Pacific superplumes, bu...

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/...

The two dominant features in the present-day mantle are the antipodal African and Pacific Large Low Shearwave Velocity Provinces (LLSVPs), or superplumes. How were these two structures formed? Are they fixed and long-lived through Earth history, or dynamic and linked to the supercontinent cycles? Such first-order questions concerning how geodynamic...

Chemical diversity in Archaean tonalite–trondhjemite– granodiorite (TTG) rocks has been commonly proposed to reflect variable depth of melting [1]. TTGs preserving ‘highpressure’ signatures have been associated with deep subduction to >70 km depth [2,3] or overthickening of mafic plateaus [4]. However, the residual TTG source rocks are mostly absen...

Mantle stable isotope heterogeneities resulting from high-temperature processes have been reported for a growing number of elements. Among them, Zn is of great interest due to its single valence state (Zn 2+) in compounds or complex ions which makes it insensitive to redox conditions. Zn isotopic compositions (δ 66 Zn, relative to JMC-Lyon) in igne...

Full text link: https://authors.elsevier.com/a/1XRj65aRZOEdY Sun et al. (2017) reported petrographic, chemical and Os isotope data on eleven mantle xenoliths from the Obnazhennaya kimberlite and claimed that their results enable them to establish “the character of the lithospheric mantle beneath the northern Siberian craton” . Here we show that th...

Share Link: https://authors.elsevier.com/a/1WVH73p4ZCXbu The Obnazhennaya kimberlite in the NE Siberian craton hosts a most unusual cratonic xenolith suite, with common rocks rich in pyroxenes and garnet, and no sheared peridotites. We report petrographic and chemical data for whole rocks (WR) and minerals of 20 spinel and garnet peridotites from O...

The Zn isotope data (expressed as δ66Zn) of 25 Archean crustal rocks (3.4–2.7 Ga) from the Pietersburg block in the northern part of the Kaapvaal craton (South Africa) exhibit a range from + 0.26 ± 0.04‰ to + 0.46 ± 0.04‰. This indicates the existence of resolvable Zn isotope heterogeneity in the continental lithosphere. Because the samples are rep...

To investigate metal fractionation in mantle differentiation processes, Zn stable isotopes in peridotites have a great potential as sensitive tracer of mantle partial melting, metasomatism and mineral segregation. Yet, Zn isotope data on mantle peridotites remain scarce and exclusively originating from continental settings (e.g. cratonic, off-crato...

ABSTRACT (270 words): The study presents major and trace element compositions of whole-rocks and minerals of 24 spinel harzburgite xenoliths from the Lac Michèle locality in the northern part of the Kerguelen Archipelago (South Indian Ocean). The samples are modally homogeneous and large enough to provide representative whole-rock samples. Their Mg...

We present new Zn elemental and isotope data on seventeen fertile and refractory mantle peridotite xenoliths. Eleven fertile peridotites are garnet and spinel lherzolites from Vitim and Tariat (Siberia and Mongolia) and represent some of the most pristine fertile peridotites available. Six refractory peridotites are spinel harzburgites from the Uda...

Ureilites are highly fractionated ultramafic achondrites that also have some primitive characteristic, such as heterogeneous ∆ 17 O values. They are usually considered to be derived from a single parent body (UPB). The chemical composition and texture of ureilites indicate that they could be mantle residues after ~15-30% basaltic melt extraction du...

Ureilites are the second largest group of differentiated meteorites (260 specimens) after the HED (Howardite-Eucrite-Diogenite) meteorite group. These meteorites are currently considered coming from the same parent body called the "ureilite parent body" (UPB) that has not been discovered yet. Actually, it has been proposed that the UPB has been des...

The formation age of the lithospheric mantle of the Siberian craton (one of the largest on Earth) is not well established; nearly all published whole-rock Re–Os data are for mantle xenoliths from a single kimberlite in the center of the craton (Udachnaya). We report Re–Os isotope and PGE concentration data for 19 spinel and garnet peridotite xenoli...

The formation age of the Siberian cratonic mantle is not well established. Re-Os data on various mantle-derived materials brought up by kimberlite magmas have shown that it contains Archean components, but the reported ages range broadly (3.4 to <1 Ga). We report Re-Os isotope and PGE concentration data for a suite of 29 fresh, well-characterized x...

The formation age of the Siberian cratonic mantle is not well established. Re–Os data on various mantle-derived materials brought up by kimberlite magmas have shown that it contains Archean components, but the reported ages range broadly (3.4 to <1 Ga). We report Re–Os isotope and PGE concentration data for a suite of 29 fresh, well-characterized x...

Mantle processes fractionate transition metal stable isotopes as documented by distinct Fe isotope compositions of peridotite xenoliths in comparison to basalts. Partial melting and oxidation state control transition metal isotopic compositons, although their respective roles remain to be quantified. In contrast with Fe, Zn with an unique valence s...

The authors regret that incorrect values were reported in the abscissa axis of Fig. 10 of the original version of this paper. The correct Fig. 10 with scale ranging from 0 to 4 Ga is given here.

Ureilites are the second largest group of differentiated meteorites (260 specimens) after the HED (Howardite-Eucrite-Diogenite) meteorite group. These meteorites are currently considered coming from the same parent body called the "ureilite parent body" (UPB) that has not been discovered yet. Actually, it has been proposed that the UPB has been des...

We present Zn isotope data on fresh garnet and spinel peridotite xenoliths from Vitim and Tariat (central Asia) to explore potential heterogeneities of fertile mantle, which is currently assumed to be unaffected by Zn isotope fractionation, i.e. homogeneous, as inferred from studies of MORB, OIB and serpentinized orogenic peridotites [1]. The 13 pe...

http://www.sciencedirect.com/science/article/pii/S0016703714002348 The processes that control water distribution in nominally anhydrous minerals from peridotites are twofold. Melt depletion will remove water while metasomatism can potentially add water to these minerals. These processes can lead to a wide range of outcomes in water contents, which...

Water is believed to be a key factor controlling the long-term stability of cratonic lithosphere [1], but mechanisms responsible for the water content distribution in the mantle remain poorly constrained. Water contents were obtained by FTIR in olivine, pyroxene and garnet for 20 well-characterized peridotite xenoliths from the Udachnaya kimberlite...