Examining Magma History from Grains of Olivine

Darlene and Ian at Mt. Tabor; Amber Olivine Grains

Vogt Scholar Darlene Gilroy reports: “I am currently in the picking stage of lab work. In this stage, I am using a microscope to look at crushed scoria and “pick” out specific grains of olivine. The scoria is from the Boring Volcanic Mt. Tabor. After finishing the Mount Tabor samples I will move on to my other sample sites, also Boring Volcanic: Prune Hill, Mount Scott, and Battle Ground Lake. The olivine grains will be mounted in epoxy and sent off for electron microprobe and Fourier-transform infrared spectroscopy to establish the rate of ascent and storage depth of magma for the Boring volcanics. I recently sent samples from all four locations to WSU for bulk geochemical analysis.” Photo left: Darlene and retired DOGAMI geologist/GSOCer Ian Madin at her Mt. Tabor field site reconning for our 2023 Boring Buttes field trip. Photo right: view under a microscope showing olivine which are the “amber colored” grains among the darker scoria.