Bulletin of Volcanology

, Volume 51, Issue 3, pp 161–176

Crystallization history of Obsidian Dome, Inyo Domes, California


  • Samuel E. Swanson
    • Geology and Geophysics Department and Geophysical InstituteUniversity of Alaska
  • Michael T. Naney
    • Chemistry DivisionOak Ridge National Laboratory
  • H. R. Westrich
    • Geochemistry DivisionSandia National Laboratory
  • J. C. Eichelberger
    • Geochemistry DivisionSandia National Laboratory

DOI: 10.1007/BF01067953

Cite this article as:
Swanson, S.E., Naney, M.T., Westrich, H.R. et al. Bull Volcanol (1989) 51: 161. doi:10.1007/BF01067953


Samples obtained by U.S. Department of Energy research drilling at the 600-year-old Obsidian Dome volcano provide the rare opportunity to examine the transition from volcanic (dome) to plutonic (intrusion) textures in a silicic magma system. Textures in the lavas from Obsidian Dome record multiple periods of crystallization initiated in response to changes in undercooling (ΔT) related to variable degassing in the mag-ma. Phenocr)ysts formed first at low ΔT. A drastic increase in ΔT, related to loss of a vapor phase during initial stages of eruption, caused nucleation of microlites. All of the lavas thus contain phenocrysts and microlites. Extrusion and subsequent devitrification of the dry (0.1 wt% H2O) magma crystallized spherulites and fine-grained rhyolite at high ΔT. A granophyric texture, representing crystallization at a moderate ΔT, formed in the intrusions beneath Obsidian Dome. Textures in the intrusion apparently represent crystallization of hydrous (1–2 wt% H2O) rhyolitic magma at shallow depths.

Copyright information

© Springer-Veriag 1989