Lyderic France

University of Lorraine | UdL · CRPG - Centre de Recherches Pétrographiques et Géochimiques

Time constraints on igneous processes related to eruption triggering, e.g., magma mixing or ascent in the conduit, are needed in any risk mitigation attempt. In this context, magma ascent rate and kinetics are key parameters as they may correspond to the response time available to civil protection during volcanic unrest. Several tools available to...

At oceanic spreading centers, the interactions between the igneous system that builds the crust, and the hydrothermal system that cools it govern the plumbing system architecture and its thermokinetic evolution. At fast‐spreading centers, most of those interactions occur around the axial magma lens (AML) that feeds the upper crust, and possibly par...

Carbonatites are unusual C-rich alkaline magmas that have been reported throughout the geological record. Nevertheless, there is only one currently active carbonatite system on Earth: Oldoinyo Lengai stratovolcano in northern Tanzania (God's mountain in Maasai culture). Present-day Lengai carbonatites are natrocarbonatites, peculiar Na-rich carbona...

In a classic model of evolution of the non-cratonic continental mantle lithosphere, harzburgites represent the refractory (<5% clinopyroxene) residues of high degrees of partial melting of fertile mantle, while lherzolites (>5% clinopyroxene) represent residues of lesser degrees of partial melting. However, partial melting is not the only process t...

Volcanism is the surface expression of extensive magmatic systems, with their intrusive counterpart representing ~80% of the total magma budget. Our knowledge of igneous processes therefore largely relies on our understanding of deep plutonic processes. In continental or oceanic environments, most of the intrusive igneous rocks bear geochemical cum...

The kinematics, modes of assembly, and the processes governing the evolution of magmas shape plutonic intrusions. Granite bodies have been suggested to emplace incrementally, with successive magmatic batches locally solidified as dikes or sills. Yet, the complexity and longevity of large-scale plutons hinders a unified model for their emplacement a...

Deciphering deep magmatic processes driving the onset of continental break-up is fundamental to constrain our understanding of plate tectonics. The East African Rift System (EARS) is the only currently active system on Earth to study distinct stages of rift evolution. We present a coupled analysis of melt and fluid inclusions in the Virunga Volcani...

The Afar region is one of the only places on Earth where magmatic continental rifting and associated ongoing break-up processes are exposed onshore. The several active magmatic segments there are characterized by contrasted morphologies, crustal thicknesses, magma production rates, and magma-tectonic styles. In the Erta Ale Range rift segment, exte...

Igneous microtextures are significant tracers of magmatic processes as these provide important information about magma evolution. Oxy-symplectite intergrowth of orthopyroxene (host) with Fe-Ti oxide (lamellae) is described from the Atlantis Bank, an Oceanic Core Complex (OCC) along the ultraslow spreading Southwest Indian Ridge (SWIR). This texture...

Carbonatites, carbon-rich magmatic rocks, are thought to form by low-degree partial melting of a relatively carbon-poor mantle followed by protracted differentiation and immiscibility. However, the nature of parental magmas and the characteristics of the early stages of differentiation that shape the subsequent crystal and liquid lines of descent r...

Active volcanic craters are highly dynamic geological features that undergo morphological changes on a broad range of spatial and temporal scales. Such changes have implications for the stability of the edifice, the eruptive style and the associated hazards. However, monitoring the morphological evolution of active craters at high spatial resolutio...

Trace-element partitioning between gregoryite, nyerereite, and natrocarbonatite melt is primordial for understanding trace-element distribution and fractionation in alkali-rich carbonatites. However, trace-element data are scarce for gregoryite and nyerereite. Here, we provide the first partition coefficients and lattice strain model parameters for...

Brown amphibole is a minor but common mineral component in lower oceanic crust. It is generally interpreted as products of migrating SiO2 and H2O-rich fluids or melts, which can be either residual melts from advanced magmatic differentiation of Mid-Ocean Ridge Basalt (MORB), or hydrothermal fluids including a seawater component. Within the lower oc...

Owing to the lack of persistent magma chamber and the complex interplay between magmatism and tectonism at slow- to ultraslow-spreading ridges, the likeliness of fractional crystallization being the predominant process of evolution of crustal magmas is weak. Here, we report a detailed petro-geochemical investigation from the lower crustal gabbroic...

Lithium and hydrogen are volatile elements which diffuse rapidly in crystals and melt, making them powerful geochemical tools to reconstruct geological processes that take place on short time scales, such as syn- and post-eruptive degassing. Although the dynamics of hydrogen are fairly well understood to better constrain such processes, the assessm...

The mechanism governing the kinetic growth of olivine in dynamic volcanic settings has been the subject of considerable attention in recent years. Under variable cooling rate (CR) and undercooling (−ΔT) regimes, the textual maturation of olivine proceeds from skeletal/dendritic crystals to polyhedral morphologies by infilling of the crystal framewo...

Reactive porous or focused melt flows are common in crystal mushes of mid-ocean ridge magma reservoirs. Although they exert significant control on mid-ocean ridge magmatic differentiation, their role in metal transport between the mantle and the ocean floor remains poorly constrained. Here we aim to improve such knowledge for oceanic crust formed a...

Volcanism is the surface expression of extensive magmatic systems, with their intrusive counterpart representing~80% of the total magma budget. Our knowledge of igneous processes therefore largely relies on our understanding of deep plutonic processes. In continental or oceanic environments, most of the intrusive igneous rocks bear geochemical cumu...

L'ophiolite d'Oman montre une coupe complète de lithosphère océanique générée au niveau d'une ride rapide. Dans la partie supérieure de la croûte, sous les basaltes en coussins, les dykes du complexe filonien s'enracinent dans les gabbros isotropes. Dans ces derniers, des contacts sécants gabbro dans gabbro matérialisent des nombreuses injections m...

Magma migration and differentiation processes are key to understanding the development and evolution of oceanic magma reservoirs. To provide new quantitative geochemical constraints on these processes, we applied a high‐resolution approach to study an interlayered section of the lower oceanic crust sampled at Atlantis Bank, on the (ultra)slow‐sprea...

The exposure of gabbroic sequences at Oceanic Core Complexes (OCC) along ultraslow- to slow-spreading ridges permits the study of the processes forming the lower oceanic crust. On top of the Atlantis Bank OCC along the ultraslow-spreading Southwest Indian Ridge, IODP Expedition 360 drilled Hole U1473A, mainly composed of primitive olivine gabbros i...

In order to elucidate the kinetic partitioning of cations between olivine and basalt, we performed undercooling (−ΔT) and cooling rate (CR) experiments at atmospheric pressure and QFM-2 buffer. Starting from the superliquidus temperature of 1250 °C, a Hawaiian tholeiitic basalt was cooled at the rates of 4 (CR4), 20 (CR20), and 60 (CR60) °C/h to th...

Beneath slow‐spreading ridges, melt bodies are generally considered to represent ephemeral magma reservoirs filled with crystal mushes. Formation of the oceanic crust requires at least partial extraction of melts from these crystal mushes. However, melts collection and extraction are processes yet to be fully constrained. We investigate olivine gab...

Quantifying water contents in the lithospheric mantle is key to our understanding of global geodynamics, mantle composition, and related physical properties. Most mantle lithologies (peridotite) contain little water (~50 ppm), but petrological heterogeneities such as pyroxenites are more hydrous (~300 ppm) relative to the mantle rocks. Pyroxenites...

Mineral-hosted melt inclusions have become an important source of information on magmatic processes. As the number of melt inclusion studies increases, so does the need to establish recommended practice guidelines for collecting and reporting melt inclusion data. These guidelines are intended to ensure certain quality criteria are met and to achiev...

Studying processes involved in magma accumulation and transfer is one of the keys to understand the architecture and evolution of volcanic plumbing systems. One of the main processes, magma differentiation, governs the thermal evolution and chemical composition of the melt-crystal assemblage (magma or mush depending on the relative proportions), an...

Several ODP-IODP expeditions drilled oceanic core complexes interpreted as exhumed portions of lower crust close to the ridge axis, and provide the community with invaluable sampling opportunity for further constraining magmatic processes involved in the formation of the slow-spreading lower oceanic crust. ODP Hole 735B presents the most primitive...

Carbonatites are unusual, carbon-rich magmas thought to form either by the melting of a carbon-rich mantle source or by low-degree partial melting of a carbon-poor (<80 ppm C) mantle followed by protracted differentiation and/or immiscibility. Carbonate-bearing mantle xenoliths from Oldoinyo Lengai (East African Rift), the only active volcano erupt...

Radiogenic isotope compositions of bulk lavas have been used for decades to infer the extent and length scale of mantle heterogeneity resulting from extraction of partial melts and subduction recycling processes. However, owing to melt mixing, fractional crystallisation, and assimilation, lavas do not reliably record the mantle compositional hetero...

Excel spreadsheet for prediction of rare earth element partitioning between clinopyroxene and alkaline melts

Trace element partitioning between minerals and liquids provides crucial constraints on igneous processes. We quantified trace element concentrations in clinopyroxene (Cpx) phenocrysts and their phonolite melt inclusions from the 2007–08 eruption of Oldoinyo Lengai (Tanzania), and report Cpx-melt partition coefficients (D) and corresponding partiti...

809 deep IODP Hole U1473A at Atlantis Bank, SWIR, is 2.2 km from 1,508‐m Hole 735B and 1.4 from 158‐m Hole 1105A. With mapping, it provides the first 3‐D view of the upper levels of a 660‐km² lower crustal batholith. It is laterally and vertically zoned, representing a complex interplay of cyclic intrusion, and ongoing deformation, with kilometer‐s...

Oceanic crust accreted at mid-ocean ridges represents ~70% of Earth's surface; nevertheless magmatic processes implicated in the formation of the lower crust remain poorly understood. Fossilized sections document its complexity in structure and composition, and recent studies show that melt migration and interactions within a crystallizing mush are...

Layered portions of gabbros were described at slow-spreading environments in at least two different Oceanic Core Complexes (OCC), which are interpreted as exhumed portions of lower crust at the ridge axis. Two ODP-IODP Holes drilled into the Atlantis Bank OCC (SW Indian Ridge) present locally such features, which provide essential insights on melts...

Magma evolution in the lower oceanic crust affects the metal contents in the derivative magmas and the formation of seafloor massive sulfides. At spreading segments with low magma supply, sulfide differentiate primarily by melt-mantle reaction, with subordinate role of fractional crystallization 1,2. At spreading segments with high magma supply, di...

We report field observation, age, chemical (major and trace elements), and isotope (Sr-Nd-Pb) data for felsic volcanic rocks from Central Afar and adjacent western margin. Investigated volcanic rocks are dominantly rhyolites with minor trachytes, and they are geochemically similar. Their ages range from ~30 Ma (prerift stage), ~20 Ma (early synrift...

Felsic rocks are minor in abundance but occur ubiquitously in International Ocean Discovery Program Hole U1473A, Southwest Indian Ridge. The trace element abundances of high-Ti brown amphibole, plagioclase, and zircon in veins, as well as the presence of myrmekitic texture in the studied felsic rocks support crystallization origin from highly-evolv...

Oldoinyo Lengai is the only volcano on Earth currently erupting natrocarbonatites, of which the source and genesis remain controversial. Cognate xenoliths and fumaroles were sampled at the summit of Oldoinyo Lengai, and deep crustal xenoliths from Oltatwa maar, in 2010 and 2014, after the 2007-2008 sub-Plinian eruption. The summit cognate xenoliths...

Although the axial melt lens (AML) beneath fast-spreading mid-ocean ridges has been detected by seismic reflection for decades, its nature and role in the accretion of lower oceanic crust and the evolution and eruption of mid-ocean ridge basalts (MORB) are still poorly constrained. Plutonic rocks consisting of quartz-bearing gabbros, diorites and t...

Mantle metasomatism by percolating melts/fluids can significantly modify the geochemical and mineralogical compositions of the sub-continental lithospheric mantle (SCLM). We present a detailed study of water contents and Li concentrations and isotopic compositions in mantle minerals from a suite of peridotite xenoliths entrained by a Cenozoic Strom...

At fast-spreading mid-ocean ridges (MORs), the horizon between the axial melt lens (AML) and the overlying sheeted dikes is characterized by extensive anatectic processes. The heat flux of the AML in combination with hydrothermal fluids from above causes high-grade contact metamorphism, which may result in anatexis of the roof rocks above the AML....

The existence of narrow axial volcanic zones of mid-oceanic ridges testifies of the underlying concentration of both melt distribution and tectonic strain. As a result of repeated diking and faulting, axial volcanic zones therefore represent a spectacular topographic expression of plate divergence. However, the submarine location of oceanic ridges...

The modal, chemical, and isotopic compositions of mantle peridotite are largely modified by metasomatic processes, which may affect them repeatedly. Xenoliths are commonly used to characterize those metasomatic processes along with the structure, and chemical and isotopic compositions of mantle domains. Nevertheless, the original mantle signatures...

The two main magmatic properties associated with explosive eruptions are high viscosity of silica-rich magmas and/or high volatile contents. Magmatic processes responsible for the genesis of such magmas are differentiation through crystallization, and crustal contamination (or assimilation) as this process has the potential to enhance crystallizati...

At oceanic spreading centers, interactions between magma and hydrothermal convecting systems trigger major physical, thermal, and chemical exchanges. The two-pyroxene hornfels recovered from the base of the sheeted dike sequence at Integrated Ocean Drilling Program (IODP) Site 1256 (equatorial Eastern Pacific) is interpreted as a conducting boundar...

International Ocean Discovery Program (IODP) Expedition 360 was the first leg of Phase I of the SloMo (shorthand for "The nature of the lower crust and Moho at slower spreading ridges") Project, a multiphase drilling program that proposes to drill through the outermost of the global seismic velocity discontinuities, the Mohorovičić seismic disconti...

The aim of this paper is to provide a report on the IODP expedition 360 to the Polish geoscientific community. Expedition 360 to the Atlantis Bank along the Southwest Indian Ridge was Leg 1 of the SloMo Project. The primary objective of the SloMo Project is to test competing hypotheses on the nature of the Moho at the slow-spreading oceanic lithosp...

The genesis and evolution of carbonatitic magmas, and the origin of their extreme enrichment in rare earth elements (REE), remain poorly understood. The Oldoinyo Lengai volcano, located in northern Tanzania is the only active volcano which produces such magmas. A set of new samples collected from the flanks of Oldoinyo Lengai allows the processes o...

The oxydation state of Earth’s upper mantle (OSEUM) is a key thermodynamic parameter as it influences, among other variables, the depth of melting initiation, the liquidus/solidus temperatures and the composition of mantle melts, the speciation of numerous species (e.g., Fe, S, V…), the phase relations, the trace element partitionning, the volcanic...