Petrologic monitoring of 1981 and 1982 eruptive products from mount st. Helens.

@article{Cashman1983PetrologicMO,
  title={Petrologic monitoring of 1981 and 1982 eruptive products from mount st. Helens.},
  author={Katharine V Cashman and J E Taggart},
  journal={Science},
  year={1983},
  volume={221 4618},
  pages={1385-7}
}
New material from the dacite lava dome of Mount St. Helens, collected soon after the start of each successive extrusion, is subjected to rapid chemical and petrologic analysis. The crystallinity of the dacite lava produced in 1981 and 1982 is 38 to 42 percent, about 10 percent higher than for products of the explosive 1980 eruptions. This increase in crystallinity accompanies a decrease in the ratio of hornblende to hornblende plus orthopyroxene, which suggests that the volatile-rich, crystal… CONTINUE READING