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Publications scientifiques

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Modélisation d’équilibre de phase prédictive des faciès d’altération associés aux gîtes à oxydes de fer-cuivre-or dans les terrains de hauts grades métamorphiques

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général - core.ac.uk - PDF: publications.polymtl.ca

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Patterns of albitization in the montgenèvre ophiolite, western alps

...The principal product of the albitization reaction, which affects all sea-floor rocks, is normally assumed to be pure, ordered albite. In the feldspathic rocks of the Montgenèvre ophiolitic complex (western Alps), the product is albite s.l. ; its An content and the extent of its departure from the ordered state can be monitored by its cell parameters. In terms of the β* - γ* plot, the gabbroic and basaltic rocks now contain albite of composition between An₀ and An₁₀. Most data-points indicate a slight disorder in the product. In contrast, the albite in leucocratic dyke-rocks (now albitite) characteristically is in the range An₀ to An₃, and better ordered. The euhedral albite that was deposited in an alpine cleft in red shale, in the top part of the complex, is An₅, not An₃ as expected. Important mineralogical gradients occur in the case of juxtaposed lithologies. Perhaps because of the overwhelming quantity of the reactant, anorthositic gabbro typically contains a more calcic albite, implying limited circulation of seawater in these assemblages. The two dominant feldspathic lithologies seem to define distinct paths of albitization, presumably as a result of different bulk compositions of the original plagioclase. The finer the grain size of a rock, the closer is the albite likely to be to the equilibrium product. The general lack of attainment of equilibrium indicated implies that the episode of regional greenschist-facies ocean-floor metamorphism (Jurassic) was short-lived....

général - core.ac.uk -

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Évolution géodynamique des zones internes des cordillères bétiques (andalousie, espagne) : apports d’une étude pluridisciplinaire du complexe alpujárride

...The Betic-Rif Cordillera, located in the western Mediterranean region, forms a narrow, arcuate orogenic belt. By comparison with other orogenic belts in the Mediterranean realm, its geodynamic evolution is higly controversial because of a long and complex tectono-metamorphic history, including the Mesozoic rifting and the Alpine orogenesis where subduction, collisional and post-orogenic extensional events are successively recorded. This Ph.D.thesis aims to address two major issues about the geodynamic evolution of the Alpujárride Complex, a group of metamorphic units that belong to the Internal Zones of the Betic Cordillera.Two study areas have been investigated with (i) the peridotitic massifs located in the western part of this complex whose mechanisms and timing of exhumation remain unclear and (ii) the tectonic units located further east that display well-preserved high pressurelow temperature (HP/LT) mineral parageneses related to the Alpine subduction episode but with high uncertainties regarding the age of this metamorphic event.This work has been carried out by following a multi-scale and multi-disciplinary approach, from the outcrop- to the regional-scale, including detailed field mapping, structural measurements, petrographic observations, Raman thermometry and 40Ar/39Ar dating....

général - core.ac.uk - PDF: tel.archives-ouvertes.fr

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