Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 31 July 2009:
Vol. 325. no. 5940, pp. 545 - 546
DOI: 10.1126/science.1176882
Prev | Table of Contents | Next

Perspectives

Geochemistry:

Ironing Out the Oxidation of Earth's Mantle

Marc M. Hirschmann

Lavas from island arc volcanoes form when the crust is recycled into the mantle at subduction zones (see the figure). These lavas are more oxidized than those produced at mid-ocean ridge volcanoes. On page 605 of this issue, Kelley and Cottrell (1) use a high–spatial resolution method to determine iron oxidation states of glasses from a suite of volcanic rocks, including a broad sampling of tiny inclusions trapped in minerals from arc volcanoes that have not undergone degassing. They correlate these measurements with dissolved water and trace element concentrations determined by other microanalytical techniques, and link the oxidation of arc volcano magmas with oxidants in the fluids that infiltrate the mantle wedge above subduction zones, as opposed to other processes, such as volcanic degassing in surface regions.

Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, USA.

E-mail: marc.m.hirschmann-1{at}umn.edu

Read the Full Text

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)