Shallow level low-sulphidation type epithermal systems in the Regec caldera, Central Tokaj Mts., NE-Hungary

B. Bajnoczi, F. Molnár, K. Maeda, E. Izawa

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Detailed investigation of the Regec caldera in the Central Tokaj Mts. revealed several types of hydrothermal centers of low-sulphidation type formed at different paleolevels. At the paleosurface, a hydrothermal eruption breccia and layered siliceous deposit of opal-C and -CT material with cinnabar and anomalous enrichments of Hg and Sb were formed from a hot spring. Silicified tuff horizons with alunite-kaolinite alteration indicate steam-heated zones. This type of alteration was formed in the near surface zone, probably above the paleowater table. Stable isotope data for large-sized alunite crystals in brecciated tuff may also indicate a magmatic steam origin. In the deeper zone, around 90-140 m minimal paleodepth, adularia-sericite alteration with quartz veining in andesite formed with anomalous Sb, As and Ba concentrations. Two stages of K-feldspar formation can be recognized: 1. metasomatic K-feldspar, replacing plagioclase phenocrysts, and 2. late adularia in quartz-pyrite-veinlets. Intensive brecciation and adularia formation suggest a pressure drop and boiling of the mineralizing fluids. Late stage quartz crystals show frequent homogenization temperatures between 170 and 190°C and a maximum salinity of 3 wt. % NaCl equiv. Stable isotope data for quartz crystals suggest that the dominant mineralizing fluid was meteoric water that underwent exchange reaction with the host rock and/or mixed with magmatic water.

Original languageEnglish
Pages (from-to)217-227
Number of pages11
JournalGeologica Carpathica
Volume51
Issue number4
Publication statusPublished - 2000

Fingerprint

caldera
adularia
quartz
alunite
crystal
tuff
feldspar
stable isotope
siliceous deposit
paleosurface
cinnabar
fluid
opal
thermal spring
pressure drop
meteoric water
breccia
andesite
host rock
kaolinite

Keywords

  • Epithermal systems
  • Fluid inclusions
  • Low-sulphidation type
  • Stable isotopes
  • Tokaj Mountains

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

Shallow level low-sulphidation type epithermal systems in the Regec caldera, Central Tokaj Mts., NE-Hungary. / Bajnoczi, B.; Molnár, F.; Maeda, K.; Izawa, E.

In: Geologica Carpathica, Vol. 51, No. 4, 2000, p. 217-227.

Research output: Contribution to journalArticle

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