SCANDIUM MINERALOGY: PRETULITE WITH SCANDIAN ZIRCON AND XENOTIME-(Y) WITHIN AN APATITE-RICH OOLITIC IRONSTONE FROM SAINT-AUBIN-DES-CHATEAUX, ARMORICAN MASSIF, FRANCE

2002 ◽  
Vol 40 (6) ◽  
pp. 1657-1673 ◽  
Author(s):  
Y. Moelo ◽  
Y. Lulzac ◽  
O. Rouer ◽  
P. Palvadeau ◽  
E. Gloaguen ◽  
...  
Keyword(s):  
Armorican Massif ◽  
Oolitic Ironstone

scholarly journals Polygenic chamosite from a hydrothermalized oolitic ironstone (Saint-Aubin-des-Châteaux, Armorican Massif, France): crystal chemistry, visible–near-infrared spectroscopy (red variety) and geochemical significance

Clay Minerals ◽  
2020 ◽  
Vol 55 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Yves Moëlo ◽  
Emmanuel Fritsch ◽  
Eric Gloaguen ◽  
Olivier Rouer
Keyword(s):  
Near Infrared ◽  
Vanadium Content ◽  
Published Data ◽  
Octahedral Sheet ◽  
New Variety ◽  
Intervalence Charge Transfer ◽  
Geochemical Significance ◽  
Red Variety ◽  
Armorican Massif ◽  
Oolitic Ironstone

AbstractSeveral generations of chamosite, including a red variety, occur in the Ordovician hydrothermalized oolitic ironstone from Saint-Aubin-des-Châteaux (Armorican Massif, France). Their chemical re-examination indicates a low Mg content (0.925 < Fe/(Fe + Mg) < 0.954), but a significant variation in IVAl. Minor vanadium is present at up to 1.1 wt.% oxide. Variations in IVAl, the vanadium content and the colour of chamosite are related to the hydrothermal reworking of the ironstone. Taking into account other published data, the ideal composition of chamosite is (Fe5–xAl1+x)(Si3–xAl1+x)O10(OH)8, with 0.2 < x < 0.8 (0.2: equilibrium with quartz; 0.8: SiO2 deficit). The red chamosite (IIb polytype) has a mean composition of (Fe3.87Mg0.23Mn0.01□0.07Al1.74V0.07)(Si2.33Al1.67)O10(OH)8. This chamosite is strongly pleochroic, from pale yellow (E || (001)) to deep orange red (E ⊥ (001)). Visible–near-infrared absorbance spectra show a specific absorption band centred at ~550 nm for E ⊥ (001), due to a proposed new variety of Fe/V intervalence charge-transfer mechanism in the octahedral sheet, possibly Fe2+ – V4+ → Fe3+ – V3+. While the formation of green chamosite varieties is controlled by reducing conditions due to the presence of organic matter as a buffer, that of red chamosite would indicate locally a weak increase of fO2 related to oxidizing hydrothermal solutions.

scholarly journals Palaeozoic oolitic ironstone of the French Armorican Massif: a chemical and structural trap for orogenic base metal–As–Sb–Au mineralisation during Hercynian strike-slip deformation

2007 ◽  
Vol 42 (4) ◽  
pp. 399-422 ◽  
Author(s):  
Eric Gloaguen ◽  
Yannick Branquet ◽  
Philippe Boulvais ◽  
Yves Moëlo ◽  
Jean-Jacques Chauvel ◽  
...  
Keyword(s):  
Base Metal ◽  
Strike Slip ◽  
Structural Trap ◽  
Slip Deformation ◽  
Armorican Massif ◽  
Oolitic Ironstone

scholarly journals Large-scale relief development related to Quaternary tectonic uplift of a Proterozoic-Paleozoic basement: The Armorican Massif, NW France

2000 ◽  
Vol 105 (B8) ◽  
pp. 19273-19288 ◽  
Author(s):  
Stéphane Bonnet ◽  
François Guillocheau ◽  
Jean-Pierre Brun ◽  
Jean Van Den Driessche
Keyword(s):  
Large Scale ◽  
Tectonic Uplift ◽  
Paleozoic Basement ◽  
Armorican Massif

Rb–Sr and 40Ar/39Ar ages in blueschists from the Ile de Groix (Armorican Massif, France): Implications for closure mechanisms in isotopic systems

2005 ◽  
Vol 220 (1-2) ◽  
pp. 21-45 ◽  
Author(s):  
Valérie Bosse ◽  
Gilbert Féraud ◽  
Michel Ballèvre ◽  
Jean-Jacques Peucat ◽  
Michel Corsini
Keyword(s):  
Armorican Massif

Planalvus (Brachiopoda, Athyridida) from the Lower Devonian of the Armorican Massif, northwest France

1994 ◽  
Vol 68 (3) ◽  
pp. 451-460 ◽  
Author(s):  
Patrick R. Racheboeuf ◽  
Paul Copper ◽  
Fernando Alvarez
Keyword(s):  
New Species ◽  
North America ◽  
Lower Devonian ◽  
Eastern North America ◽  
Lower Carboniferous ◽  
Armorican Massif ◽  
A New Species

Cryptonella? cailliaudi Barrois, 1889, from the Lower Devonian of the Armorican Massif, is tentatively assigned to the athyridid brachiopod genus Planalvus Carter, thus far known only from the Lower Carboniferous of eastern North America. In addition, a new species, Planalvus rufus, is described from the Bois-Roux Formation (Pragian) of Brittany, France. These French species are small brachiopods with complex spiralial and jugal structures, which permit assignment to the order Athyridida.

Palaeozoic history of the Armorican Massif: Models for the tectonic evolution of the suture zones

2009 ◽  
Vol 341 (2-3) ◽  
pp. 174-201 ◽  
Author(s):  
Michel Ballèvre ◽  
Valérie Bosse ◽  
Céline Ducassou ◽  
Pavel Pitra
Keyword(s):  
Tectonic Evolution ◽  
History Of ◽  
Armorican Massif

Fingerprinting the provenance of building stones: a case study on the Louvigné and Lanhélin granitic rocks (Armorican massif, France)

2014 ◽  
Vol 185 (1) ◽  
pp. 13-31 ◽  
Author(s):  
Claudine Malfilatre ◽  
Erwan Hallot ◽  
Philippe Boulvais ◽  
Marc Poujol ◽  
Annick Chauvin ◽  
...  
Keyword(s):  
Building Stone ◽  
Granitic Rocks ◽  
Magnetic Characteristics ◽  
Building Stones ◽  
Intrinsic Variability ◽  
Geological Unit ◽  
Qualitative Variables ◽  
Identity Cards ◽  
Armorican Massif

Abstract Two examples of granitic stones from Brittany (western France) commercialized under the names of “gris-bleu de Louvigné” and “bleu de Lanhélin” were characterized in order to explore how the provenance of a building stone can be traced back with a maximum of confidence. For this purpose, petrographical, geochemical and magnetic characteristics, representing more than 70 quantitative and qualitative variables, were compiled for a total of 32 samples. We have defined two reference populations for these building stones and have extracted their discriminative characteristics. We have then compared four randomly selected samples and two foreign commercial counterparts of these stones to the reference populations. Discriminative variables differ from one case of comparison to the other, which indicates that a combination of various tools and variables will be generally required to unequivocally fingerprint the origin of a given granitic stone. Where several quarries are mining a single geological unit within a composite intrusion, the provenance of a granitic rock can be defined at the scale of the intrusion. In addition, stones coming from two different intrusions from the same batholith can be distinguished. We conclude that the provenance of any granitic building stone is identifiable, especially if the intrinsic variability of a population of samples representative of that stone has been previously circumscribed. This study underlines that the compilation of databases for building stone identity cards is an essential first step toward the creation of official labels guaranteeing stone provenances.

Sign in / Sign up

Export Citation Format

Share Document