ceinture de roches vertes
- Domaine
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- géologie
Note :
Roches vertes : Expression désignant d'une manière générale l'ensemble des [roches magmatiques] plutoniques et effusives, basiques et ultrabasiques, dont le teinte verte est due au développement de chlorite, épidote, amphibole, et serpentine, du fait de l'altération et, plus souvent, du métamorphisme (cf. prasinite, amphibolite, serpentine).
Termes :
Termes associés :
- bande volcano-sédimentaire n. f. Canada
- ceinture volcano-sédimentaire n. f. Canada
- sillon volcano-sédimentaire n. m. Canada
- ceinture aurifère n. f.
- greenstone belt critiqué
- ceinture à greenstones critiqué
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[greenstone belt] Emprunt lexical.
[greenstone belt | ceinture à greenstones] Termes utilisés en France.
[ceinture à greenstones] Calque lexical.
Traductions
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anglais
Auteur : Université Laval,Définition
Elongate or beltlike area within Precambrian shields that contain the deformed and metamorphosed rocks of one or more volcano-sedimentary piles, in each of which there is typically a trend from mafic to felsic volcanics.
Notes :
Greenstone: A field term applied to any compact dark green altered or metamorphosed basic igneous rock (e.g. spilite, basalt, gabbro, diabase) that owes its color to the presence of chlorite, actinolite, or epidote.
Gold-quartz veins and Algoma-type banded iron-formations are present in nearly all greenstone belts, but volcanogenic massive sulfide deposits are most abundant in some of the younger belts such as the Canadian. Archean massive sulfides are the largest of their class, accumulating over submarine fumarolic alteration pipes atop the felsic rocks which close an eruptive cycle. A typical greenstone volcanic pile shows repeated cyclical mafic to felsic assemblages, locally containing more than one ore zone.Termes :
- greenstone belt
- belt