Hydrothermal alteration of plagioclase in granitic rocks from Proterozoic basement of SE Sweden

S. Morad, M. A K El-Ghali, M. A. Caja, M. Sirat, K. Al-Ramadan, H. Mansurbeg

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Petrographic examinations and electron microprobe analyses of Proterozoic granitic rocks, SE Sweden aimed to characterize and unravel the mechanisms and conditions of plagioclase alterations. These alterations include saussuritization, albitization and replacement of plagioclase by K-feldspar. The hydrothermal alterations, which are inferred to have occurred at ca. 250-400°C, resulted in concomitant formation of Alrich titanite, epidote, calcite, pumpellyite, prehnite and iron oxides. Replacement of plagioclase by K-feldspar occurs in red-stained zones, which have developed close to thin fractures owing to the precipitation of tiny Fe-oxide pigment particles within the altered plagioclase, whereas saussuritized plagioclase has less systematic spatial relationships to these fractures. Albitization of plagioclase occurred in rocks that are poor in biotite compared to rocks that suffered extensive saussuritization. The chemical and textural characterization of various types of plagioclase alterations allows elucidation of the granitic hydrothermal systems. Features of feldspar alteration in the granitic rocks are similar to those encountered in feldspathic sandstones and should hence be considered in studies on diagenetic changes of siliciclastic successions during basin evolution.

Original languageEnglish
Pages (from-to)105-116
Number of pages12
JournalGeological Journal
Volume45
Issue number1
DOIs
Publication statusPublished - Jan 2010

Fingerprint

hydrothermal alteration
Proterozoic
plagioclase
rock
albitization
feldspar
replacement
pumpellyite
prehnite
titanite
epidote
hydrothermal system
basin evolution
electron probe analysis
iron oxide
pigment
biotite
calcite
sandstone
oxide

Keywords

  • Albitization
  • Granite
  • Hydrothermal alteration
  • Saussuritization
  • Secondary K-feldspar

ASJC Scopus subject areas

  • Geology

Cite this

Hydrothermal alteration of plagioclase in granitic rocks from Proterozoic basement of SE Sweden. / Morad, S.; El-Ghali, M. A K; Caja, M. A.; Sirat, M.; Al-Ramadan, K.; Mansurbeg, H.

In: Geological Journal, Vol. 45, No. 1, 01.2010, p. 105-116.

Research output: Contribution to journalArticle

Morad, S. ; El-Ghali, M. A K ; Caja, M. A. ; Sirat, M. ; Al-Ramadan, K. ; Mansurbeg, H. / Hydrothermal alteration of plagioclase in granitic rocks from Proterozoic basement of SE Sweden. In: Geological Journal. 2010 ; Vol. 45, No. 1. pp. 105-116.
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