Chemical and boron isotopic variations of tourmaline in the Hnilec granite-related hydrothermal system, Slovakia: Constraints on magmatic and metamorphic fluid evolution

Shao Yong Jiang, Martin Radvanec, Eizo Nakamura, Martin Palmer, Katsura Kobayashi, Hai Xiang Zhao, Kui Dong Zhao

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Multi-stage formation of tourmaline occurs in the Hnilec granite-related hydrothermal tin mineralisation system from the Western Carpathians, Slovakia. The tourmalines belong to the schorl-dravite series and have two major stages of formation: the majority crystallized during the first stage (defined as M-stage), forming zoned tourmaline crystals with the cores being generally more Fe, Al, and Mn rich than the rims. During the second stage (defined as L-stage), tourmaline formed as small veins or irregular patches along fractures and cracks in the M-stage tourmaline grains. In the contact metapelites near the granite body, the L-stage tourmalines are more Mg-rich and Fe, Al, Mn depleted than the M-stage tourmalines. In the granites, the L-stage tourmalines have generally similar compositions to those of the M-stage tourmaline rims. The boron isotopic compositions of the M-stage tourmalines vary from - 10.3‰ to - 15.4‰; with no clear variation between the cores and the rims, however, some of the tourmaline grains from the contact metapelites show a slightly higher δ11B in the cores than in the rims. The L-stage tourmalines have lower δ11B value of - 16.0‰ to - 17.1‰. We suggest that these trends reflect a changing fluid source from a dominant magmatic-hydrothermal fluid derived from the granites to a late-stage metamorphic fluid derived from the regional metamorphism (chlorite and biotite zone) in the metapelites. The significantly higher Fe3+ in the L-stage than the M-stage tourmalines reflect changing redox conditions towards a more oxidising environment. This redox condition change may have important implications for the hydrothermal tin mineralisation in the area.

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalLITHOS
Volume106
Issue number1-2
DOIs
Publication statusPublished - Nov 1 2008

Keywords

  • Boron isotopes
  • Hydrothermal mineralisation
  • Magmatic
  • Metamorphic
  • Tourmaline
  • Western Carpathia

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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