Der OH-Gehalt von Kluftquarzen aus den österreichischen Alpen
- Autor(en)
- Birgit Hertweck, Anton Beran, Gerhard Niedermayr
- Abstrakt
Quartz is sometimes not only rich in fluid inclusions, quartz also contains traces of hydrogen which are incorporated in its crystal structure in form of OH groups. OH contents in dry mineral systems are of geologic interest as they could be used as an indicator for the H2O- activity prevailing during the formation of the crystal. IRspectroscopy provides an extremely sensitive method for the determination of very low OH contents down to the range of few tenths of wt.ppm H2O. IR-spectroscopic measurements have been performed on 124 usually slightly zoned crystal plates cut perpendicular to the c-axis of quartz from Alpine veins in the Penninic Zone, the Greywacke Zone, and the Central Alpine nappes. Four OH spectra types can be discerned which are based on the intensity ratios of three absorption bands: an absorption band at 3380 cm-1 due to Al-OH defects, a band at 3480 cm-1 caused by Li-OH defects and a band at 3595 cm-1 created by B-OH defects. Type A is characterized by a dominating Al-OH band and a Li-OH band with half the Al-OH band intensity and a weak B-OH band. In type B the Li-OH band shows an intensity even to that of the Al-OH band. In type C Al-OH and weaker Li-OH bands are present, no B-OH band can be observed. In type D only the Al-OH band is present. Spectra type A is dominating in quartz with relatively low OH contents (between 1 and 3 wt.ppm H2O). Type D has been observed in quartz crystals containing less than 2 ppm OH. Type C covers the region between 3 and 6 ppm OH followed by type B with OH contents up to 20 ppm. Quartz crystals rich in OH which belong to type B are apparently related to high concentrations of Li-OH defects. Those crystals preferentially occur in the Ankogel-group region. The practically “dry” type D quartz crystals show a preferred occurrence in the region of the Venediger-group and in the Lungau.
- Organisation(en)
- Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- Naturhistorisches Museum Wien (NHM)
- Journal
- Mitteilungen der Österreichischen Mineralogischen Gesellschaft
- Band
- 165
- Seiten
- 99-117
- Anzahl der Seiten
- 19
- ISSN
- 1609-0144
- Publikationsdatum
- 09-2019
- ÖFOS 2012
- 105116 Mineralogie, 104026 Spektroskopie
- Link zum Portal
- https://ucris.univie.ac.at/portal/de/publications/der-ohgehalt-von-kluftquarzen-aus-den-oesterreichischen-alpen(e9d9d4b3-18cd-452e-9c13-0f760aa619aa).html