Magmatic fluid segregation and overprinting hydrothermal processes in gabbro pegmatites of the Neotethyan ophiolitic Szarvaskö Complex (Bükk Mountains, NE Hungary)

Attila Péntek, F. Molnár, David H. Watkinson

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Pegmatites of the Szarvaskö Ophiolite Complex, Bükk Mts, NE Hungary were classified according to their shape (pockets, dykes) and texture (zoned, homogeneous), representing different stages of fluid enrichment during crystallization of the host gabbro. Local assimilation of adjacent sedimentary rocks increased the volatile-, and incompatible-element content of the melt. Most pegmatites crystallized from a locally segregated hydrous silicate melt, but some were intruded later. Pegmatites have mineral contents similar to their host gabbro, but are enriched in amphibole, biotite, Fe-Ti-oxides, quartz, and apatite. During formation of the pegmatites a fluid phase separated and caused deuteric alteration under magmatic-submagmatic conditions. Post-magmatic sea-floor hydrothermal activity is recognized by intense alteration and formation of a greenschist facies mineral assemblage at temperatures of 250-400 °C. Fluid inclusion studies revealed two aqueous fluid types related to this polyphase hydrothermal process. Alpine regional metamorphism caused intense deformation of the rocks, accompanied by veining of a low-grade metamorphic mineral assemblage. Primary fluid inclusions in vein-filling minerals and chlorite thermometry were used to obtain proposed conditions of 270-285 °C and 150-200 MPa for this process.

Original languageEnglish
Pages (from-to)433-446
Number of pages14
JournalGeologica Carpathica
Volume57
Issue number6
Publication statusPublished - Dec 2006

Fingerprint

overprinting
gabbro
mountain
fluid
mineral
fluid inclusion
silicate melt
regional metamorphism
hydrothermal activity
greenschist facies
ophiolite
amphibole
apatite
chlorite
biotite
sedimentary rock
crystallization
seafloor
texture
melt

Keywords

  • Alpine metamorphism
  • Bükk Mts
  • Deuteric alteration
  • Gabbro pegmatite
  • Hungary
  • Magmatic fluid
  • Sea-floor hydrothermal alteration

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

Magmatic fluid segregation and overprinting hydrothermal processes in gabbro pegmatites of the Neotethyan ophiolitic Szarvaskö Complex (Bükk Mountains, NE Hungary). / Péntek, Attila; Molnár, F.; Watkinson, David H.

In: Geologica Carpathica, Vol. 57, No. 6, 12.2006, p. 433-446.

Research output: Contribution to journalArticle

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