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Le district aurifère de Challant (Val d'Aoste-Italie) : gîtologie, géochimie et métallogénie de l'or

Abstract : In the auriferous Monte Rosa Province , the Challant district appears as a geological unit and is situated near the Arcesa island. These rocks are paleozoic gneiss surrounded by the Piemonte ophiolite nappe. The district extends South of Ranzola major fault which is the North limit of gneiss . They are typical epigenetic lodes : it may be assumed that their period of deposition fell between 50 and 30 My. It is possible to range the hundred of deposits in two types : quartz, native gold and low sulfides (mean gold grade 12 g/t), quartz and pyrite (mean gold grade 7g/t) . We may assume that the gold stores equal at least 1 t , and possibly even 5 t . Various analytical methods have been used such as Spark Source Mass Spectrometrywe have studied all elements (major, minor and trace) in gneiss, quartz , native gold, listvenites and pyrites coming from differents deposits. Auriferous pyrites are easily distinguished from non auriferous pyrites on the basis of trace elements . In this district, some trace elements such as Sb, As, Ag, Cu , Hg, Bi, Te may be gold indicators and their use in systematic soil prospection is proposed . From geological, ore deposit and geochemical data, a secretion metamorphic origin for gold of the Challant district is discussed.
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Contributor : Pascale Talour <>
Submitted on : Friday, October 12, 2012 - 11:12:43 AM
Last modification on : Wednesday, November 29, 2017 - 3:02:13 PM
Long-term archiving on: : Saturday, December 17, 2016 - 12:26:48 AM


  • HAL Id : tel-00741254, version 1



Annick Richard. Le district aurifère de Challant (Val d'Aoste-Italie) : gîtologie, géochimie et métallogénie de l'or. Géologie appliquée. Universite Scientifique et Médicale de Grenoble, 1981. Français. ⟨tel-00741254⟩



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