Michel Cuney

French National Centre for Scientific Research | CNRS · Institut national des sciences de l'univers (INSU)

The Bohemian Massif hosts significant hydrothermal U-deposits associated with shear zones in the high-grade metamorphic basement. But there is a lack of evidence of a genetic link between mineralization and U-fertile igneous rocks. This contribution provides constraints on the major U source of the vein-type U-deposits, the timing of ore formation...

Multi-element EMP maps and analyses of major accessory phases and their possible alteration products from ultrapotassic rocks (durbachites), in combination with LA-ICP-MS analyses of hydrothermal U-mineralization, provided constraints on potential U source of vein-type U-deposits in the Moldanubian Zone of the Bohemian Massif. The extensive metal m...

The southeastern French Massif Central represents an ideal area to study the linkage between regional metamorphism, crustal partial melting, emplacement of granitic magmas, and hydrothermal Sn-W mineralization in a polyphase tectono-metamorphic setting related to the late-Variscan orogeny. Here, we describe the mineralogical, structural, geochemica...

The Bafq district, well-known in the world, is the most important iron province in Central Iran. The Early Cambrian volcano-sedimentary sequence in this district, hosts a lot of mineral deposits such as Kiruna-type iron oxide-apatite (IOA), Fe-Mn exhalative and Pb-Zn SEDEX types. Th-U-REE mineralisation in the Bafq IOA deposits occurs in a variety...

The Baishuizhai, Shituling and Zhushanxia deposits from the Xiazhuang district represent to date the only known occurrences of early Yanshanian (Middle to Upper Jurassic) granite-related high-temperature hydrothermal uranium deposits (175–145 Ma) in the Nanling Metallogenic Belt, South China. Whole-rock geochemistry of ore samples combined with che...

The giant Huayangchuan deposit in the Qinling Orogen is a newly discovered U-Nb-polymetallic deposit mainly hosted in Triassic carbonatite. Petrographic, elemental, and isotopic composition analyses of uraninite were conducted to determine the formation and evolution of this deposit. At Huayangchuan, four types of uraninite are identified. Pristine...

The Kitongo uranium deposit is located in the northwestern margin of the post-tectonic alkaline batholith of Kogué emplaced at ca. 550–530 Ma. The hydrothermal alteration system that affected the Kitongo granite is manifested by two albitization events characterized by the development of aegirine–albitites (Na-metasomatites). These albitization eve...

In the Xiangshan volcanic complex, South China, U-(Th) mineralization occurred in two major stages: (i) an early Cretaceous (ca. 120-105 Ma), magmatic-related high temperature hydrothermal stage characterized by structurally controlled Th-rich brannerite and pitchblende associated with ThREE -Y-Nb-Zr-rich mineral phases in albitized zones; and (ii)...

The Gleibat Lafhouda dolomite carbonatites of the Moroccan Sahara occur as three separate cone-shaped plugs intruding an autochthonous succession of Archean supracrustal basement rocks. Geochemically, the Gleibat Lafhouda dolomite carbonatites are characterized by a compositional range of 11.3–27.1 wt% MgO, 3.1–29.7 wt% CaO, 3.5–38.0 wt% FeOtot and...

The Mayo-Kebbi massif (Chad) exposes a Neoproterozoic juvenile crustal segment that has been tectonically accreted in the Central African Orogenic Belt and reworked during the Pan-African orogeny. It comprises a syntectonic high-K magmatic suite including the Zabili A-type granitic pluton. The Zabili pluton is made of a highly differentiated granit...

This thematic issue is in memory of Thomas Kurtis Kyser who died tragically in 2017. Kurt’s contribution to our understanding of the geochemistry of uranium deposits and the application of stable and radiogenic isotope studies to uranium ore systems is incalculable. His research on uranium deposits included the world-class unconformity-related uran...

Wolframite has been proposed as a U/Pb geochronometer for direct dating of W mineralisation events, but its isotopic analysis may be hampered by highly variable and low U contents (<200 ppm) and low ²⁰⁶Pb/²⁰⁴Pb ratios (〈300), heterogenous common Pb compositions, post-crystallisation alteration, and the presence of non-cogenetic mineral and fluid in...

Sandstone type deposits are the most common type of uranium deposits in the world. A large variety of sub-types have been defined, based either on the morphology of the deposits (e.g. tabular, roll front, etc), or on the sedimentological setting (e.g. paleovalley, paleochannel, unconformity), or on tectonic or lithologic controls (e.g. tectonolitho...

In the Xiazhuang and Zhuguang uranium ore fields of the Nanling Metallogenic Belt, southeast China, granite-related hydrothermal uranium deposits formed in two major mineralisation stages: (i) an early Yanshanian high-temperature stage (175-145 Ma) concomitant with the regional post-orogenic Jurassic intraplate magmatism; and (ii) a late Yanshanian...

The Puy-les-Vignes W deposit, located in the northwestern French Massif Central (FMC), is a rare occurrence of a wolframite-mineralized hydrothermal breccia pipe hosted in high-grade metamorphic gneisses. We present an integrated study of this deposit aiming to characterize the ore-forming hydrothermal system in link with the Variscan late-orogenic...

We describe the multi-scale distribution of K, Th and U in the ca. 3.1 Ga Heerenveen batholith of the Barberton Granite-Greenstone Terrain. Data were obtained with a combination of tools, including a portable gamma-ray spectrometer from the scale of the whole batholith to the scale of outcrops, and autoradiography for the thin section scale. U is c...

The Volcanic-related Be-U-Mo Baiyanghe deposit is located in the Paleozoic Xuemisitan Volcanic Belt in West Junggar (NW China). It is the largest Be deposit in Asia which is dominantly hosted in late Devonian rhyolitic tuff and in the late Carboniferous Yangzhuang granite (313±2 Ma) that were emplaced after the closure of the Junggar oceanic domain...

The stabilization of Archaean cratons is accompanied by a transition from juvenile granitic magmatism, to reworking of the pre-existing crust. In this work, we examine the granitoids associated to the ca. 3.1 Ga stabilization of the Kaapvaal Craton of Southern Africa, and investigate the origin and petrogenesis of the granodiorite-monzogranite-syen...

The new whole-rock geochemistry and Sr-Nd-Pb isotope data obtained for U-bearing Na-metasomatites (albitites) in the Central Ukrainian Uranium Province (CUUP) are presented and discussed in terms of the possible contribution of different sources of elements to this type of uranium deposit. When compared with the host granite, albitites demonstrate...

The Longshoushan Metallogenic Belt (northwestern China) is known for its word-class Jinchuan Ni-Cu sulfide (Pt) deposit and is also an important uranium metallogenic belt. The Jiling uranium deposit in this belt is a typical Na-metasomatic uranium deposit, which rarely occurs in China. Mineralization in the Jiling uranium deposit is hosted in grani...

Volcanic-related hydrothermal U deposits from the Xiangshan ore field are situated within the Gan-Hang Metallogenic Belt in South China. These deposits are dominantly hosted in late Yanshanian felsic volcanic rocks that were emplaced during the Yanashanian post-orogenic extension. The host volcanic rocks are moderately fractionated high-K calc-alka...

The W-Sn Maoping deposit and related W-Sn deposits from the world-class Nanling Range in Southeast China formed at ca. 160 Ma and experienced several phases of metal addition and metal redistribution between 160 and 130 Ma. Isotopic dating of ore mineral (wolframite) of Maoping demonstrates that W was deposited first, during a hydrothermal event at...

Nuclear geology is the application of the physics of the nucleus, and of the effects of particles and radiation emitted by the nucleus, to geology. It includes the study of the effects of the interaction of nuclear particles and radiation with geological materials. A variety of techniques are used to measure the physical and chemical properties of...

Peraluminous pegmatoids (PGDs) from the central Grenville Province show LREE enrichments up to 7435 ppm hosted in monazite or allanite. These PGD are compared with their migmatitic metapelitic source to elaborate a petrogenetic model for these peculiar magmas. The leucosome has low ΣREE content (39 ppm) consistent with its Pl+K-Fsp-dominated assemb...

The Early Cretaceous (ca. 130 Ma) Nb-rich and Ta-poor Huangshan suite, South China, includes a series of medium-grained granites that contain Nb-rich mica and very low columbite contents, which are indicative of a potential Nb resource. In addition, the Huangshan suite contains fine-grained granites and aplo-pegmatites in which disseminated Nb–Ta c...

Southern India and Sri-Lanka are the places where “incipient charnockites”, i.e. the local transformation of amphibolite-facies gneisses into orthopyroxene-bearing, igneous looking charnockites, have been discovered in the early sixties. The fact that some incipient charnockites occur along a network of brittle fractures, together with CO 2 remnant...

A database of European granite-related uranium deposits containing the average grade and resources for individual ore deposits has been constituted from the resources declared by the countries available in the literature and in the UDEPO website of the IAEA. This database was used to evaluate the statistical distribution of deposit size and grade a...

This paper aims at providing new insights into the W-Sn ore-forming processes within one of the largest granitic provinces in the world (Nanling Range, South China), which was emplaced during the Jurassic-Cretaceous period. The origin, composition and pressure-temperature conditions of fluids involved in the W-Sn ore-forming processes have been inv...

In rare-metal granites, niobium and tantalum are generally hosted by Nb-Ta oxides. However, in SE China, the Nb-specialized Huangshan granites are a unique occurrence in which Nb is essentially hosted by LiFe micas. The Huangshan granites are part of the Early Cretaceous (Late Yanshanian) Lingshan granite complex and belong to the A-type granite se...

Silurian organic-rich black shales are widespread and serve as basic source for most U mineralization throughout the entire Variscan Orogen of Central and Western Europe. In particular the lowermost unit of Silurian black shales is regionally strongly enriched in U. The strong U-enrichment of these shales is the result of the Hirnantian glaciation...

At present, the Comisión Nacional de Energía Atómica, in cooperation with the National University of Córdoba, is carrying out the project entitled Melallogenesis of Granite-Related Uranium Deposits in Argentina within the framework of an IAEA coordinated research project which is Geochemical and Mineralogical Characterization of Uranium and Thorium...

In the French Armorican Variscan belt, most of the economically significant hydrothermal U deposits are spatially associated with peraluminous leucogranites emplaced along the south Armorican shear zone (SASZ), a dextral lithospheric scale wrench fault that recorded ductile deformation from ca. 315 to 300 Ma. In the Pontivy-Rostrenen complex, a com...

The Uranium exploration history of the Central African Republic (CAR) extends on two periods separated by the independence in 1960, of the ex-Ubangi-Chari, a colony of French Equatorial Africa. The uranium research is contemporary of theFrench Atomic Energy Commission (CEA) implementation in this country in 1947 and done by the CEA. There began the...

This publication defines a new classification scheme that is simple and descriptive but flexible enough to encompass the recent advances in the understanding of uranium geology and deposit genesis. Improved definitions of the deposit types, supported by examples for which good data are available, but which are not well described in previous literat...

We present a complete dataset for major, minor and trace elements in wolframite ([Fe,Mn]WO4) based on the example of several peribatholitic hydrothermal W deposits located in the Variscan French Massif Central (FMC). The wolframite samples were characterized down to the micrometer scale by combining scanning electron microscopy observations and in...

Many studies have proved the usefulness of Li-mica and chlorite geochemistry as indicators of the chemical and thermal evolution of magmatic systems. This study highlights the suitability of Li-micas as tracers of hydrothermal mineralizing events in world-class W-Sn deposits associated with Jurassic (190–150 Ma) granites in China through the comple...

We present U-Pb thermal ionization mass spectrometer (TIMS) ages of wolframite from several granite-related hydrothermal W±Sn deposits in the French Massif Central (FMC) located in the internal zone of the Variscan belt. The studied wolframite samples are characterized by variable U and Pb contents (typically <10 ppm) and show significant variation...

We present U-Pb thermal ionization mass spectrometer (TIMS) ages of wolframite from several granite-related hydrothermal W±Sn deposits in the French Massif Central (FMC) located in the internal zone of the Variscan belt. The studied wolframite samples are characterized by variable U and Pb contents (typically <10 ppm) and show significant variation...

The Beauvoir granite (Massif Central, France) represents an exceptional case in the European Variscan belt of a peraluminous rare-metal granite crosscutting an early W stockwork. The latter was strongly overprinted by rare-metal magmatic-hydrothermal fluids derived from the Beauvoir granite, resulting in a massive topazification of the quartz-ferbe...

Granite-related hydrothermal U deposits from the Xiazhuang and Zhuguang ore fields are located within the Nanling Metallogenic Belt in South China. These deposits are hosted in Triassic and Jurassic granites that were emplaced during the Indosinian orogeny and the Yanshanian post-orogenic extension. Four main types of granitic host rocks were ident...

Granite-related vein-type uranium deposits from the world-class Xiazhuang and Zhuguang ore fields are located within the Nanling Metallogenic Belt in SE China. These deposits are mainly hosted in peraluminous Indosinian and Yanshanian granites, which also represent the main uranium source rocks for the mineralization. Amongst the five deposits that...

The highest grade unconformity-type uranium deposits in the world occur in the Athabasca Basin, Canada. They are considered to be the result of mixing between oxidized basinal brines and basement-derived reduced fluids/gases, and/or reduced basement rocks. Meta-sedimentary basement rocks of the Dufferin Lake Zone, directly underlying the Athabasca...

Carboniferous–Permian, Triassic and Jurassic igneous basement rocks around the Erlian Basin in northeast China have been investigated through detailed mineralogical, whole-rock geochemistry, geochronological data and Sm–Nd isotope studies. Carboniferous–Permian biotite granites and volcanic rocks belong to a calc-alkaline association and were empla...

Most of the hydrothermal uranium (U) deposits from the European Hercynian belt (EHB) are spatially associated with Carboniferous peraluminous leucogranites. In the southern part of the Armorican Massif (French part of the EHB), the Guérande peraluminous leucogranite was emplaced in an extensional deformation zone at ca. 310 Ma and is spatially asso...

Uranium deposits are characterized by their extreme diversity in size, grade, shape, geological environment, mineralogy, etc. They form at conditions ranging from deep high-grade metamorphic to surficial environments and from Neoarchean times to the Quaternary Period. The classification of uranium deposits has been improved in the past few years us...

The Baxingtu deposit is a typical redox front tabular-shaped uranium deposit hosted in sandstones of the Late Cretaceous Yaojia Formation deposited within a braided river environment during the post-rift stage of the Songliao Basin, in north- east China. This study proposes the first metallogenic model for the Baxingtu deposit and provides new data...

Li-micas have been used as indicators of the evolution of granites. However, hydrothermal Li-micas are less documented. World-class W-Sn deposits associated with Early Yanshanian granites (South Jiangxi, China) show magmatic and hydrothermal Li-micas which could help unravelling the magmatic-hydrothermal evolution of rare metal deposits. Six types...

Dans la chaîne hercynienne européenne, la majorité des minéralisations uranifères (filons ou épisyenites) est représentée par des gisements hydrothermaux spatialement associés à des leucogranites peralumineux d’âge Carbonifère. Ainsi, dans le Massif armoricain, 20000 t d’uranium ont été extraites principalement des trois districts uranifères associ...