Sur l'existence et la nature de l'apport chimique dans certaines series cristallophylliennes

1945 ◽  
Vol S5-XV (4-6) ◽  
pp. 255-310 ◽  
Author(s):  
Pierre Lapadu-Hargues
Keyword(s):  
Chemical Composition ◽  
Special Reference ◽  
Metamorphic Rocks ◽  
Calc Alkaline ◽  
Physicochemical Factors ◽  
Alkaline Material

Abstract Distinguishes seven groups of metamorphic rocks according to chemical composition, ranging from argillaceous schists to granites and granulites, and discusses the physicochemical factors involved in the transformation of the pre-existing rocks during metamorphism, with special reference to the addition of calc-alkaline material from deep-seated magmas, the behavior of component elements, and the migration of ions during alteration.

scholarly journals Chemical Composition of Vintage Preban Absinthe with Special Reference to Thujone, Fenchone, Pinocamphone, Methanol, Copper, and Antimony Concentrations

2008 ◽  
Vol 56 (9) ◽  
pp. 3073-3081 ◽  
Author(s):  
Dirk W. Lachenmeier ◽  
David Nathan-Maister ◽  
Theodore A. Breaux ◽  
Eva-Maria Sohnius ◽  
Kerstin Schoeberl ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Special Reference

Nappes de ponces du Cantal et du Mont-Dore; leurs aspects volcanologique, petrographique et mineralogique

1966 ◽  
Vol S7-VIII (2) ◽  
pp. 223-245 ◽  
Author(s):  
Robert Brousse ◽  
Christian Lefevre
Keyword(s):  
Calc Alkaline ◽  
Granulometric Analysis ◽  
Alkaline Material

Abstract In the volcanic massifs of Mont-Dore and Cantal (Central Massif of France), Villafranchian (Pleistocene) pumice 'nappes' occur. The pumice has an acidic and tholeiitic character and represents a type of ignimbrite. It originated from calc-alkaline material formed by remobilization of the gneissic basement of the large volcanoes, followed by a mixture of basalts and products of anatectic fusion. Granulometric analysis of the ignimbrite enables location of the calderas that were the centers of eruption. The temperature of the ignimbrites at the time of their emission is estimated at 900-1000 degrees C.

scholarly journals Uraninite, Coffinite and Ningyoite from Vein-Type Uranium Deposits of the Bohemian Massif (Central European Variscan Belt)

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 123 ◽  
Author(s):  
Miloš René ◽  
Zdeněk Dolníček ◽  
Jiří Sejkora ◽  
Pavel Škácha ◽  
Vladimír Šrein
Keyword(s):  
Chemical Composition ◽  
Electron Microprobe ◽  
Bohemian Massif ◽  
Uranium Deposit ◽  
Ore Deposits ◽  
Metamorphic Rocks ◽  
Uranium Deposits ◽  
Massif Central ◽  
Vein Type ◽  
Ore District

Uraninite-coffinite vein-type mineralisation with significant predominance of uraninite over coffinite occurs in the Příbram, Jáchymov and Horní Slavkov ore districts and the Potůčky, Zálesí and Předbořice uranium deposits. These uranium deposits are hosted by faults that are mostly developed in low- to high-grade metamorphic rocks of the basement of the Bohemian Massif. Textural features and the chemical composition of uraninite, coffinite and ningyoite were studied using an electron microprobe. Collomorphic uraninite was the only primary uranium mineral in all deposits studied. The uraninites contained variable and elevated concentrations of PbO (1.5 wt %–5.4 wt %), CaO (0.7 wt %–8.3 wt %), and SiO2 (up to 10.0 wt %), whereas the contents of Th, Zr, REE and Y were usually below the detection limits of the electron microprobe. Coffinite usually forms by gradual coffinitization of uraninite in ore deposits and the concentration of CaO was lower than that in uraninites, varying from 0.6 wt % to 6.5 wt %. Coffinite from the Jáchymov ore district was partly enriched in Zr (up to 3.3 wt % ZrO2) and Y (up to 5.5 wt % Y2O3), and from the Potůčky uranium deposit, was distinctly enriched in P (up to 8.8 wt % P2O5), occurring in association with ningyoite. The chemical composition of ningyoite was similar to that from type locality; however, ningyoite from Potůčky was distinctly enriched in REE, containing up to 22.3 wt % REE2O3.

Variation in the Composition of Muscovite and Biotite in some Metamorphic Rocks near Bancroft, Ontario

1973 ◽  
Vol 10 (6) ◽  
pp. 869-880 ◽  
Author(s):  
Ermanno R. Rambaldi
Keyword(s):  
Chemical Composition ◽  
Chemical Equilibrium ◽  
Element Distribution ◽  
Metamorphic Grade ◽  
Chemical Data ◽  
Metamorphic Rocks ◽  
Exchange Equilibrium ◽  
Metamorphic Terrain ◽  
Fe Content ◽  
Compositional Study

A study of mica composition in a metamorphic terrain which displays a variation in metamorphic grade from the garnet to the sillimanite–garnet–biotite zone, has revealed that muscovite and phengite occur over the whole range of metamorphic conditions that were encountered. The distribution of Mn, Li, Ti, Na, Fe, and Mg between these minerals and coexisting biotite shows many regularities which are interpreted in relation to exchange equilibrium. Two trends of element distribution are suggested, corresponding to the association phengite–biotite and muscovite–biotite. The chemical composition of the mica minerals is not correlative with metamorphic grade.A compositional study of phengite has revealed that the Fe2+/Fe3+ ratio in this mineral is higher in rocks that contain epidote than in rocks that are free of epidote.The distribution of Na and K between muscovite and plagioclase is affected by the Fe content of muscovite and the An content of plagioclase.Mineralogical and chemical data from the study area provide an indication that a generalized chemical equilibrium was established in the rocks during metamorphism.

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