Nb-Ta fractionation in peraluminous granites: A marker of the magmatic-hydrothermal transition - Archive ouverte HAL Access content directly
Journal Articles Geology Year : 2016

Nb-Ta fractionation in peraluminous granites: A marker of the magmatic-hydrothermal transition

(1) , (1) , (1) , (2, 1, 3) , (4, 5) , (6)
1
2
3
4
5
6

Abstract

In their late stages of evolution, peraluminous granitic melts exsolve large amounts of fluidswhich can modify the chemical composition of granitic whole-rock samples. The niobium/tantalum (Nb/Ta) ratio is expected to decrease during the magmatic differentiation of graniticmelts, but the behavior of both elements at the magmatic-hydrothermal transition remainsunclear. Using a compilation of whole-rock geochemical data available in the literature, wedemonstrate that fractional crystallization alone is not sufficient to explain the distribution ofNb-Ta in most peraluminous granites. However, we notice that most of the granitic samplesdisplaying evidence of interactions with fluids have Nb/Ta < 5. We propose that the decreaseof the Nb/Ta ratio in evolved melts is the consequence of both fractional crystallization andsub-solidus hydrothermal alteration. We suggest that the Nb/Ta value of ~5 fingerprints themagmatic-hydrothermal transition in peraluminous granites. Furthermore, a Nb/Ta ratio of ~5appears to be a good marker to discriminate mineralized from barren peraluminous granites.
Fichier principal
Vignette du fichier
GEOLOGY-S-15-01034.pdf (1.64 Mo) Télécharger le fichier
Origin : Files produced by the author(s)

Dates and versions

insu-01270578 , version 1 (17-12-2021)

Identifiers

Cite

Christophe Ballouard, Marc Poujol, Philippe Boulvais, Yannick Branquet, Romain Tartese, et al.. Nb-Ta fractionation in peraluminous granites: A marker of the magmatic-hydrothermal transition. Geology, 2016, 44 (3), pp.231-234. ⟨10.1130/G37475.1⟩. ⟨insu-01270578⟩
378 View
101 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More