Holocene Age Dike-fed Silicic Domes and Flows in Oregon and California

Silicic Domes

Pre-meeting field trip, August 9-12th; max/min participants, 15/7

Oregon and California contain some of the world’s best exposed and most carefully studied chains of dike-fed, glassy lava domes and flows. This kind of extrusive-explosive assemblage, which has never been observed while active, contains key structural, chemical, and textural information about the volatile evolution and associated hazards of silicic magmatic systems. This four-day pre-conference field trip will examine sets of domes at Newberry and South Sister Volcanoes in central Oregon, and Medicine Lake Volcano in northern California. Our emphasis will be on how the physical and chemical processes responsible for the textural and structural diversity of these domes and associated explosive products can be inferred from field relations and laboratory simulations. We will visit Newberry on August 9, South Sister on August 10, and Medicine Lake on August 11-12. Participants will hike over some rough dome surfaces and flow fronts and will have the option of either a strenuous climb to the top of South Sister Volcano or a chairlift ride to the summit of nearby Mount Bachelor. Good boots and leather gloves are recommended. The route should also offer excellent views of Mount Hood, Mount Jefferson, North and Middle Sister, Mount Washington, Mount Thielsen, Mount McLoughlin, and Mount Shasta.

Participants will need to arrive in Portland on Tuesday, August 8, and will have Sunday, August 13, to explore Portland before the start of the meeting. The trip will leave Portland on Wednesday morning, August 9, spend two nights in Bend, one night in or near Klamath Falls, and return to Portland on Saturday evening.

Estimated cost:
$650/person.  Includes transportation, double occupancy rooms*, breakfast (except for August 9th), lunch and snacks.  Participants are responsible for their own dinners each night. (* A few single occupancy rooms may be available for an additional $100.)

Jonathan Fink, Portland State University
Steven Anderson, University of Northern Colorado