On the origin of zoned grossular-andradite garnets in hydrothermal systems

Journal article

Grossular-andradite (grandite) garnets from contact skarns and hydrothermal veins commonly show extensive intracrystalline zonation of major and trace elements. The paper examines some of the factors that may affect the garnet composition at equilibrium and non-equilibrium conditions. Grandite-solution - aqueous-solution equilibria have been evaluated by using a general form of Lippmann's solutus equation. The grandite composition is very sensitive to variations in temperature and the pH, fO2 and salinity of the hydrothermal solution due to the difference in the aqueous complexation behaviour between Al and Fe. Pressure variation has little effects on the aqueous complexation, but may indirectly affect the garnet composition through pressure-sensitive equilibria that involve other minerals. The effects of variable kinetic dispersion in a hydrothermal system with fluctuations in the fluid flow rate are illustrated though a low-order reaction and transport model. -from Authors

Authors: Jamtveit, B; Ragnarsdottir, K; Wood, B

• Publication status: Published
• Journal: EUROPEAN JOURNAL OF MINERALOGY
• Volume: 7
• Issue: 6
• Pages: 1399-1410
• Publication date: 1995-01-01
• DOI: 10.1127/ejm/7/6/1399
• ISSN: 0935-1221
• Language: English
• Keywords: hydrothermal garnets; equilibrium; non-equilibrium; zonation