References of "Duchesne, Jean-Clair"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailShort note: Synthetic ilmenite as a blank to XRF trace element determination
Duchesne, Jean-Clair ULg; Bologne, Guy

in Geologica Belgica (2011), 14(1-2), 103-106

Detailed reference viewed: 11 (0 ULg)
Full Text
Peer Reviewed
See detailXRF major and trace element determination in Fe-Ti oxide minerals
Duchesne, Jean-Clair ULg; Bologne, Guy

in Geologica Belgica (2009), 12(3-4), 205-212

Detailed reference viewed: 39 (5 ULg)
Full Text
Peer Reviewed
See detailA-type magmatic suites as tracers of the lower crust
Vander Auwera, Jacqueline ULg; Bogaerts, Michel; Liégeois, Jean-Paul et al

in AGC/GAC – AMC/MAC – SEG – SGA Abstract Volume (2008), 33

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
See detailThe Grader layered intrusion (Havre-Saint-Pierre anorthosite, Québec) and genesis of nelsonite and other Fe-Ti-P ores
Charlier, Bernard ULg; Sakoma, Emmanuel; Sauvé, Martin et al

in Lithos (2008), 101(3-4), 359-378

The Grader layered intrusion is part of the Havre-Saint-Pierre anorthosite in the Grenville Province (Quebec, Canada). This intrusion has a basin-like morphology and contains significant resources of ... [more ▼]

The Grader layered intrusion is part of the Havre-Saint-Pierre anorthosite in the Grenville Province (Quebec, Canada). This intrusion has a basin-like morphology and contains significant resources of Fe–Ti–P in ilmenite and apatite. Outcropping lithologies are massive oxide alternating with anorthosite layers, banded ilmenite–apatite–plagioclase rocks and layered oxide apatite (gabbro-)norites. Drill cores provide evidence for stratigraphic variations of mineral and whole rock compositions controlled by fractional crystallization with the successive appearance of liquidus phases: plagioclase and ilmenite followed by apatite, then orthopyroxene together with magnetite, and finally clinopyroxene. This atypical sequence of crystallization resulted in the formation of plagioclase–ilmenite–apatite cumulates or “nelsonites” in plagioclase-free layers. Fine-grained ferrodiorites that cross-cut the cumulates are shown to be in equilibrium with the noritic rocks. The high TiO2 and P2O5 contents of these assumed liquids explains the early saturation of ilmenite and apatite before Fe–Mg silicates, thus the nelsonites represent cumulates rather than crystallized Fe–Ti–P-rich immiscible melts. The location of the most evolved mineral and whole rock compositions several tens of meters below the top of the intrusion, forming a sandwich horizon, is consistent with crystallization both from the base and top of the intrusion. The concentrations of V and Cr in ilmenite display a single fractionation path for the different cumulus assemblages and define the cotectic proportion of ilmenite to 21 wt.%. This corresponds to bulk cotectic cumulates with ca. 8 wt.% TiO2, which is significantly lower than what is commonly observed in the explored portion of the Grader intrusion. The proposed mechanism of ilmenite-enrichment is the lateral removal of plagioclase due to its relative buoyancy in the dense ferrodiorite melt. This plagioclase has probably accumulated in other portions of the intrusion or has not been distinguished from the host anorthosite. [less ▲]

Detailed reference viewed: 138 (7 ULg)
Full Text
Peer Reviewed
See detailPost-collisional melting of crustal sources: constraints from geochronology, petrology and Sr, Nd isotopes geochemistry of the Variscan Sichevita and Poniasca granitoid plutons
Duchesne, Jean-Clair ULg; Liégeois, Jean-Paul; Iancu, Viorica et al

in International Journal of Earth Sciences (2008), 97

Detailed reference viewed: 30 (10 ULg)
Full Text
Peer Reviewed
See detailIlmenite composition in the Tellnes Fe–Ti deposit, SW Norway: fractional crystallization, postcumulus evolution and ilmenite–zircon relation
Charlier, Bernard ULg; Skar, Oyvind; Korneliussen, Are et al

in Contributions to Mineralogy & Petrology (2007), 154(2), 119-134

Major and trace element XRF and in situ LA-ICP-MS analyses of ilmenite in the Tellnes ilmenite deposit, Rogaland Anorthosite Province, SW Norway, constrains a two stage fractional crystallization model of ... [more ▼]

Major and trace element XRF and in situ LA-ICP-MS analyses of ilmenite in the Tellnes ilmenite deposit, Rogaland Anorthosite Province, SW Norway, constrains a two stage fractional crystallization model of a ferrodioritic Fe-Ti-P rich melt. Stage 1 is characterized by ilmenite-plagioclase cumulates, partly stored in the lower part of the ore body (Lower Central Zone, LCZ), and stage 2 by ilmenite-plagioclase-orthopyroxene-olivine cumulates (Upper Central Zone, UCZ). The concentration of V and Cr in ilmenite, corrected for the trapped liquid effect, (1) defines the cotectic proportion of ilmenite to be 17.5 wt% during stage 1, and (2) implies an increase of D VIlm during stage 2, most likely related to a shift in fO2. The proportion of 17.5 wt% is lower than the modal proportion of ilmenite (ca. 50 wt%) in the ore body, implying accumulation of ilmenite and flotation of plagioclase. The fraction of residual liquid left after crystallization of Tellnes cumulates is estimated at 0.6 and the flotation of plagioclase at 26 wt% of the initial melt mass. The increasing content of intercumulus magnetite with stratigraphic height, from 0 to ca. 3 wt%, results from differentiation of the trapped liquid towards magnetite saturation. The MgO content of ilmenite (1.4–4.4 wt%) is much lower than the expected cumulus composition. It shows extensive postcumulus re-equilibration with trapped liquid and ferromagnesian silicates, correlated with distance to the host anorthosite. The Zr content of ilmenite, provided by in situ analyses, is low (<114 ppm) and uncorrelated with stratigraphy or Cr content. The data demonstrate that zircon coronas observed around ilmenite formed by subsolidus exsolution of ZrO2 from ilmenite. The U-Pb zircon age of 920 ± 3 Ma probably records this exsolution process. [less ▲]

Detailed reference viewed: 111 (22 ULg)
Full Text
See detailIsotopic and geochemical constraints on the evolution of the Mazury granitoids (NE Poland)
Baginski, Boguslaw; Duchesne, Jean-Clair ULg; Martin, Hervé et al

in Koslowski, A.; Wiszniewska, Janina (Eds.) Granitoids in Poland (2007)

Detailed reference viewed: 17 (1 ULg)
Full Text
Peer Reviewed
See detailMagma chamber processes in the Tellnes ilmenite deposit (Rogaland Anorthosite Province, SW Norway) and the formation of Fe-Ti ores in massif-type anorthosites
Charlier, Bernard ULg; Duchesne, Jean-Clair ULg; Vander Auwera, Jacqueline ULg

in Chemical Geology (2006), 234(3-4), 264-290

The origin of igneous Fe-Ti oxide ores associated with massif-type anorthosites is investigated through a detailed study of the world-class Tellnes ilmenite deposit, part of the late-Proterozoic (930-920 ... [more ▼]

The origin of igneous Fe-Ti oxide ores associated with massif-type anorthosites is investigated through a detailed study of the world-class Tellnes ilmenite deposit, part of the late-Proterozoic (930-920 Ma) AMC series of the Rogaland Anorthosite Province (SW Norway). More than 100 samples from drill cores reveal significant petrographical and compositional variations within the ore body. Four zones are defined, based on variations in modal proportions and cumulus mineral assemblages: the Lower and Upper Central Zones and the Lower and Upper Marginal Zones. Plagioclase and whole-rock compositions discriminate the zones and display patterns interpreted as a result of mixing of either plagioclase-ilmenite or plagioclase-ilmenite-orthopyroxene-olivine cumulates with a melt of ferrodioritic (jotunitic) composition with a content decreasing from 80 to 20% from the margins to the central part of the ore body. Phase diagrams for a jotunitic parental magma reproduce the crystallization sequence at 5 kb. The orthopyroxene-olivine liquidus boundary is a peritectic in the Bjerkreim-Sokndal layered intrusion and a cotectic in Tellnes and this explains the differences in the sequence of crystallization of the two intrusions. The high concentration of ilmenite, well above cotectic proportions, resulted from gravity-sorting in the Tellnes ore body, which represents the lower part of a larger magma chamber. Uniform Sr isotope ratios do not support magma mixing. The cryptic layering of the ore body precludes injection as a crystal mush but favours in situ crystallization from an evolving magma in a sill-like magma chamber. The present trough-shape and mineral orientations result from deformation during gravity-induced subsidence and by up-doming of the anorthosite. Fractional crystallization of a TiO2-rich magma with ilmenite as an early liquidus mineral and plagioclase buoyancy are the principal mechanisms responsible for the formation of Fe-Ti deposits in Proterozoic massif-type anorthosites. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 106 (9 ULg)
Full Text
Peer Reviewed
See detailThe Fedorivka layered intrusion (Korosten Pluton, Ukraine): An example of highly differentiated ferrobasaltic evolution
Duchesne, Jean-Clair ULg; Shumlyanskyy, L.; Charlier, Bernard ULg

in Lithos (2006), 89(3-4), 353-376

This study documents the petrography and whole-rock major and trace element geochemistry of 38 samples mainly from a drill core through the entire Fedorivka layered intrusion (Korosten Pluton), as well as ... [more ▼]

This study documents the petrography and whole-rock major and trace element geochemistry of 38 samples mainly from a drill core through the entire Fedorivka layered intrusion (Korosten Pluton), as well as mineral compositions (microprobe analyses and separated mineral fraction analyses of plagioclase, iltnenitc, magnetite and apatite) of 10 samples. The Fedorivka layered intrusion can be divided into 4 lithostratigraphic units: a Lower Zone (LZ, 72 to thick), a Main Zone (MZ, 160 m thick), and an Upper Border Zone, itself subdivided into 2 sub-zones (UBZ(2), 40 m thick; UBZ(1), 50 m thick). Igneous lamination defines the cumulate texture, but primary cumulus minerals have been affected by trapped liquid crystallization and subsolidus recrystallization. The dominant cumulus assemblage in MZ and UBZ(2) is andesine (An(39-42)), iron-rich olivine (Fo(32-42)), augite (En(29-35)Fs(24-29)Wo(42-44)), ilmenite (Hem(1-6)), Ti-magnetite (Usp(52-78)), and apatite. The data reveal a continuous evolution from the floor of the intrusion (LZ) to the top of MZ, due to fractional crystallization, and an inverse evolution in UBZ, resulting from crystallization downwards from the roof. The whole-rock Fe/Mg ratio and incompatible element contents (e.g. Rb, Nb, Zr, REE) increase in the fractionating magma, whereas compatible elements (e.g. V, Cr) steadily decrease. The intercumulus melt remained trapped in the UBZ cumulates due to rapid cooling and lack of compaction, and cumulus mineral compositions re-equilibrated (e.g. olivine, Fe-Ti oxides). In LZ, the intercumulus melt was able to partially or totally escape. The major element composition of the MZ cumulates can be approximated by a mixing (linear) relationship between a plagioclase pole and a mafic pole, the latter being made up of all mafic minerals in (nearly) constant relative proportions. By analogy with the ferrobasaltic/jotunitic liquid line of descent, defined in Rogaland, S. Norway, and its conjugated cumulates occurring in the Transition Zone of the Bjerkreim-Sokndal intrusion (Rogaland, a monzonitic (57% SiO2) melt is inferred to be in equilibrium with the MZ cumulates. The conjugated cumulate composition falls (within error) on the locus of cotectic compositions fixed by the 2-pole linear relationship. Ulvospinel is the only Ti phase in some magnetites that have been protected from oxidation. QUIlF equilibria in these samples show that magnetite and olivine in MZ have retained their liquidus compositions during subsolidus cooling. This permits calculation of liquidus fO(2) conditions, which vary during fractionation from Delta FMQ=0.7 to -1.4 log units. Low fO(2) values are also evidenced by the late appearance of cumulus magnetite (Fo(42)) and the high V3+-content of the melt, reflected in the high V-content of the first liquidus magnetite (up to 1.85% V). (C) 2006 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 87 (3 ULg)
Full Text
Peer Reviewed
See detailMarginal mafic intrusions as indicators of downslope draining of dense residual melts in anorthositic diapirs?
Vander Auwera, Jacqueline ULg; Weis, Dominique; Duchesne, Jean-Clair ULg

in Lithos (2006), 89(3-4), 329-352

Geochemical and isotopic investigation of three small mafic intrusions (Loyning: 1250 X 150 m, Hogstad: 2000 X 200 m, Koldal: 1250 X 500 m) in the marginal zones of the Egersund-Ogna (Loyning, Koldal) and ... [more ▼]

Geochemical and isotopic investigation of three small mafic intrusions (Loyning: 1250 X 150 m, Hogstad: 2000 X 200 m, Koldal: 1250 X 500 m) in the marginal zones of the Egersund-Ogna (Loyning, Koldal) and Ana-Sira massif-type anorthosites (Hogstad) (Rogaland Anorthositic Province, south Norway: 930 Ma) provides new insights into the late evolution of anorthositic diapirs. These layered mafic intrusions are essentially of norite, gabbronorite as well as leuconorite and display conspicuous evidence of subsolidus recrystallization. In Loyning and Hogstad, the modal layering is parallel to the subvertical foliation in the enclosing anorthosite. The northern part of the Koldal intrusion cuts across the foliation of the anolthosite, whereas in its southern part the subvertical layering is parallel to the anorthosite's foliation. The regularity of the layered structures suggests that the layering was initially acquired horizontally and later tilted during the final movements of the diapirs. The least differentiated compositions of plagioclase and otthopyroxene in the three intrusions (An(59)-En(68) in Loyning, An(49)-En(64) in Hogstad and An(44)-En(61) in Koldal) and the REE contents in apatite (Hogstad) indicate that their parent magmas were progressively more differentiated in the sequence Loyning-Hogstad-Koldal. Isotopic data (Loyning: Sr-87/Sr-86: 0.70376-0.70457, epsilon(Ndt): +6.8 to +2.7; Hogstad: Sr-87/Sr-86: 0.70537-0.70588, epsilon(Ndt): +2.1 to -0.5; Koldal: Sr-87/Sr-86: 0.70659-0.70911, epsilon(Ndt): +3.5 to - 1.6) also indicate that in this sequence, parent magmas were characterized by a progressively more enriched Sr and Nd isotopic signature. In Loyning, the parent magma was slightly more magnesian and anorthitic than a primitive jotunite; in Hogstad, it is a primitive jotunite; and, in Koldal, an evolved jotunite. Given that plagioclase and orthopyroxene of the three intrusions display more differentiated compositions than the orthopyroxene and plagioclase megacryts of the enclosing anorthosites, it is suggested that the parent magmas of the small intrusions are residual melts after anorthosite formation which were entrained in the anorthositic diapir during its rise from lower crustal chambers. Calculated densities of primitive jotunites (2.73-2.74 at FMQ, 0.15% H2O, 200 ppm CO2, 435 ppm F, 1150 degrees C, 3 kb) and evolved jotunites (2.75-2.76 at FMQ, 0.30% H2O, 400 ppm CO2, 870 ppm F, 1135 degrees C, 3 kb) demonstrate that they are much denser than the plagioclase of the surrounding anorthositic crystal mush (2.61-2.65). Efficient migration and draining of dense residual melts through the anorthositic crystal mush could have taken place along sloping floors (zones of lesser permeability in the mush), which occur along the margins of the rising anorthositic diapirs. This process takes into account the restricted occurrence of the mafic intrusions in the margins of the massif anorthosites. In a later stage, when the anorthosite was nearly consolidated, the residual melts were more differentiated (evolved jotunites) and could have been extracted into extensional fractures in the cooling and contracting anorthositic body in a similar way as aplitic dikes are emplaced in granitic plutons. As in the Rogaland Anorthositic Province, these dikes are much more abundant than the small mafic intrusions, collection and transport along dikes was probably more efficient than draining through the crystal mush. (C) 2006 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 49 (5 ULg)
Full Text
Peer Reviewed
See detailUtilisation de la microchimie de l'otolithe pour discriminer les populations de chabots au sein du bassin de la Meuse walonne
Sonny, Damien; Bologne, Guy; Duchesne, Jean-Clair ULg et al

in Cahiers d'Ethologie (2006), 22(2), 39-50

Detailed reference viewed: 57 (2 ULg)