What is the significance of the 10Be in Cascadian volcanics?
Seema Sutarwala
Dear Seema,
10Be is a radioactive nuclide (half-life 1.5 million years) that forms by
spallation of oxygen and nitrogen in the atmosphere. It rapidly becomes
concentrated in clay rich sediments. Most magmas associated with
subduction have markedly higher 10Be relative to magmas from mid-ocean
ridges and ocean islands. The higher 10Be of subduction zone magmas
suggest recent incorportation of a young sediments. 10Be/Be values for
Cascade volcanics (undated samples from Mount St. Helens and Indian
Heaven) are low relative to young (since 1741 AD) volcanics from the
Aleutians, Central America, and Melanesia. The low 10Be in Cascade
volcanics may reflect a contribution from subducted sediment that is
older than about 6 millon years.
To learn more about 10Be you might want to read "Mantle and Slab
Contribution in Arc Magmas" by Hawkesworth and others in Annual Review of
Earth and Planetary Sciences, 1993, v. 21, p. 175-204.
Thanks for forcing me to brush up on 10Be.
Steve Mattox, University of North Dakota
Other Categories
Other Questions
To VolcanoWorld