'Water' in quartz from various rhyolitic pyroclastic horizons: A new correlation tool?
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Tartalom: http://real.mtak.hu/29461/
Archívum: MTA Könyvtár
Gyűjtemény: Status = Published





Type = Conference or Workshop Item
Cím:
'Water' in quartz from various rhyolitic pyroclastic horizons: A new correlation tool?
Létrehozó:
Biró, Tamás
Kovács, István János
Király, Edit
Falus, György
Karátson, Dávid
Bendő, Zsolt
Fancsik, Tamás
Sándorné Kovács, Judit
Dátum:
2015
Téma:
QD05 Crystallography / kristálytan
QD06 Mineralogy / ásványtan
QE Geology / földtudományok
QE02 Geochemistry / geokémia
QE06 Petrology. Petrography / kőzettan, petrográfia
Tartalmi leírás:
Structural hydroxyl contents of quartz grains from various
rhyolitic pyroclastic density current (PDC) deposits from the
Bükk Foreland Volcanic Area, Hungary, were determined by
using micro-FTIR spectrometry. Additional trace element
analysis and SEM cathodoluminescence imaging were also
performed. Structural hydroxyl content (expressed in water
equivalent) of volcanic quartz ranges from ~2,0 to ~4,1 ppm,
which is lower than those in quartz of igneous, metamorphic
and hydrothermal origin. The incorporation of structural
hydroxyl is mainly due to coupled H+ + Al3+ substitutions into
Si-tetrahedral vacancies of quartz. In addition, the presence of
molecular water is also obvious in (nano-)inclusions. The
water fugacity (?H2O) just prior to the eruption seems to be
the main factor controlling the concentration of structural
hydroxyl as manifested in its almost homogeneous distribution
regardless to the zonation of Al- or Ti-content. Quartz grains
from the studied volcanic units are characterized by diagnostic
absorption features between 3000 and 3550 cm-1, structural
hydroxyl, molecular water, Al- and Ti-contents. This suggests
the potential application of water content, the way of hydrogen
incorporation and trace element chemistry of volcanic quartz
as potential correlation tools.
Moreover, a reasonable linear correlation is observed
between the integrated area of Si-O bonds-related IR
absorption features (between 2110 and 1440 cm-1) and sample
thickness up to ~300 ?m by studying unoriented quartz
crystals. This may enable the analysis of separated quartz
crystals without the need for preparing oriented thin sections.
Típus:
Conference or Workshop Item
PeerReviewed
Formátum:
text
Azonosító:
Biró, Tamás and Kovács, István János and Király, Edit and Falus, György and Karátson, Dávid and Bendő, Zsolt and Fancsik, Tamás and Sándorné Kovács, Judit (2015) 'Water' in quartz from various rhyolitic pyroclastic horizons: A new correlation tool? In: Goldschmidt Conference, 2015. augusztus 15-21., Prága, Csehország.
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