References of "Duchesne, Jean-Clair"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailSource constraints on the genesis of Danubian granites in the South Carpathians Alpine Belt (Romania)
Duchesne, Jean-Clair ULiege; Laurent, Oscar; Gerdes, Axel et al

in Lithos (2017), 294-295

The pre-Alpine basement of the Lower Danubian nappes in the South Carpathians is made up of two Precambrian terranes (Drăgşan and Lainici-Păiuş) that were intruded by Pan-African/Cadomian and Variscan ... [more ▼]

The pre-Alpine basement of the Lower Danubian nappes in the South Carpathians is made up of two Precambrian terranes (Drăgşan and Lainici-Păiuş) that were intruded by Pan-African/Cadomian and Variscan granitoid massifs. We focus on the major and trace element geochemistry (1) in the Drăgşan terrane, of the Variscan Retezat and Parâng intrusions; (2) in the Lainici-Păiuş terrane, of the Variscan Furcǎtura, Petreanu and Frumosu intrusions and of the Pan-African Vârful Pietrii, Şuşiţa and Olteţ granites and granitic leucosomes of migmatites; and (3) in the Upper Danubian nappes basement, of the Variscan Muntele Mic, Sfârdin, Cherbelezu and Ogradena intrusions. For each intrusion, in which a range of composition is observed, we decipher the differentiation mechanisms (fractional crystallization, hybridization, melt laden with restite minerals, etc.) in order to define the parental liquid compositions. The latter are calc-alkaline to alkali-calcic (except Olteţ that is calcic) and medium to high-K in composition. With [La/Yb]N>10 and Sr/Y >15, most melts display the so-called “continental adakite” affinities. The parental melt compositions are compared with experimental data to determine the melting conditions and the nature of the source rock. When the P-T conditions can be estimated, the temperatures range between 850°C and 875°C and the pressure between 5 and 15 kbar regardless of the ages of the granites and the terrane in which they have intruded. The source rock composition is dominated by a variety of mafic igneous compositions or metasediments rich in volcanic components. Clay-rich (pelitic) protoliths have not been identified. We confirm a Variscan age (c. 300 Ma) for the Frumosu intrusion granite and inherited Precambrian ages (c. 1.7-1.9 and 2.6-2.9 Ga) for the Motru dyke swarm. Thus, both Drăgşan and Lainici-Păiuş together with the Upper Danubian basement terranes were affected by Variscan post-collisional granitic plutonism. In the South Carpathians, both Pan-African and Variscan granites were generated in a crust thickened by stacking of terranes. The source of the Pan-African granites in Lainici-Păiuş is different from that of the Variscan granites (from Lainici-Păiuş and Drăgşan terranes and from the Upper Danubian nappe basement), but all these sources were notably depleted in metapelite component. [less ▲]

Detailed reference viewed: 13 (1 ULiège)
Full Text
Peer Reviewed
See detailThe jotunites of the Korosten AMCG complex (Ukrainian shield): Crust or mantle-derived?
Duchesne, Jean-Clair ULiege; Schumlyanaskyy, Leonid; Mytrokhyn, Oleksandr

in Precambrian Research (2017), 299

Detailed reference viewed: 23 (0 ULiège)
Full Text
See detailGeochemistry of Lower Devonian terrigenous sedimentary rocks from the Belgian Ardenne: Source proxy and paleogeographic reconstruction
Duchesne, Jean-Clair ULiege; Boulvain, Frédéric ULiege

Poster (2016, July 04)

Major and trace element (Rb, Sr, Ba, Zr, Ni, V, Zn, Cr, Y, Ce) compositions are studied in Lower Devonian terrigenous sediments from the Dinant Synclinorium and Ardenne Anticline (Belgian Ardenne). Five ... [more ▼]

Major and trace element (Rb, Sr, Ba, Zr, Ni, V, Zn, Cr, Y, Ce) compositions are studied in Lower Devonian terrigenous sediments from the Dinant Synclinorium and Ardenne Anticline (Belgian Ardenne). Five cross sections encompassing 148 samples in19 formations have been studied. In the conventional [Al2O3+Fe2O3-K2O-Na2O]–[K2O]–[FeO+MgO] triangle, the rock compositions plot on the illite – chlorite tie line. This suggests that (1) the mineral association has reached equilibrium in the pressure and temperature range of the postdepositional evolution of the sediments; (2) the chemical system was open and K was a mobile component. Although the original composition of the sediment was modified, the AAFM = Al2O3/Al2O3+FeOt+MgO parameter that reflects the illite - chlorite proportions can be used as a proxy of the source composition. A principal component analysis of the major and trace element compositions permits to define the behaviour of various elements currently used as proxies of various processes. Noteworthy it is shown that Ti, V and part of Cr are correlated with the illite proportion and part of Cr, together with Zr, with resistate minerals such as quartz, chromite and zircon. The evolution with stratigraphic age in the 5 cross sections of the AAFM proxy reveals that there is a major change in the northern part of the Ardenne Anticline at the limit between the Mirwart Formation and younger formations, corresponding approximately to the Lochkovian to Pragian transition. There is a clear shift from an aluminium-rich source to a more conventional chlorite-rich source. In the paleogeographic evolution of this region the only possible source of the aluminium-rich sediment is the Rocroi Massif. This conclusion confirms sedimentological and palynological evidence that a “Rocroi Island” existed in the Lochkovian Sea. A decrease in Zr concentrations with distance to the Rocroi Massif also supports this hypothesis. The stratigraphic evolution of several parameters shows local variations that can be attributed to variable streams and depositional conditions in an alluvial deltaic or shallow sea environment. [less ▲]

Detailed reference viewed: 8 (0 ULiège)
Full Text
Peer Reviewed
See detailThe origin of nelsonite and high-Zr ferrodiorite associated with Proterozoic anorthosite
Duchesne, Jean-Clair ULiege; Liégeois, Jean-Paul

in Ore Geology Reviews (2015), 71

A petrological and geochemical (major and trace elements, Sr-Nd isotopes) study of two nelsonite occurrences (the Kydlandsvatn and Hestnes deposits) in the Rogaland anorthosite province (Southern Norway ... [more ▼]

A petrological and geochemical (major and trace elements, Sr-Nd isotopes) study of two nelsonite occurrences (the Kydlandsvatn and Hestnes deposits) in the Rogaland anorthosite province (Southern Norway) reveals that both deposits are cumulates but were generated from strikingly different magmas and processes. The Kydlandsvatn deposit was formed from a primitive jotunite similar to the Bjerkreim-Sokndal parental magma by crystal accumulation. By contrast, the Hestnes cumulate, with high REE and Zr contents, negative Eu anomaly, Cr-rich magnetite, Nb-rich ilmenite and high Nb/Ta and Zr/Hf whole-rock ratios appears to result from the crystallization of an immiscible Fe-rich and Si-poor melt under highly oxidized conditions. Other jotunites/ferrodiorites with high Zr-contents are typically associated with anorthosites in the Rogaland, Laramie and Adirondacks anorthosite complexes. In Rogaland, they also have an identical Sr-Nd isotope signature as the Hestnes nelsonite. These high-Zr jotunites cannot have been produced through extreme differentiation of ordinary jotunite magmas. Their formation from direct melting of a crustal source or assimilation of a nelsonite cumulate is highly unlikely. Occurrence of a high-Zr jotunite at the margin of a quartz mangerite dyke is evidence that immiscibility takes place, though furtively, along the jotunite liquid line of descent. It is suggested here that high-Zr jotunites in dyke rocks or parental to high Zr-nelsonites resulted from fractional crystallization of a Fe-rich immiscible melt formed at higher pressures in the polybaric evolution of anorthosites, conditions that are not yet explored experimentally. [less ▲]

Detailed reference viewed: 20 (2 ULiège)
Full Text
Peer Reviewed
See detailShort note: Synthetic ilmenite as a blank to XRF trace element determination
Duchesne, Jean-Clair ULiege; Bologne, Guy

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

Detailed reference viewed: 17 (0 ULiège)
Full Text
Peer Reviewed
See detailXRF major and trace element determination in Fe-Ti oxide minerals
Duchesne, Jean-Clair ULiege; Bologne, Guy

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

Detailed reference viewed: 43 (5 ULiège)
Full Text
Peer Reviewed
See detailA-type magmatic suites as tracers of the lower crust
Vander Auwera, Jacqueline ULiege; Bogaerts, Michel; Liégeois, Jean-Paul et al

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

Detailed reference viewed: 11 (0 ULiège)
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 ULiege; 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: 155 (7 ULiège)
Full Text
Peer Reviewed
See detailEmpirical calibration of the V partitioning between magnetite and ilmenite as an oxybarometer
Duchesne, Jean-Clair ULiege; Vander Auwera, Jacqueline ULiege; Charlier, Bernard

in EOS : Transactions, American Geophysical Union (2007), 88(52), 54-08

Detailed reference viewed: 10 (0 ULiège)