image: View into a high-pressure diamond cell of the mineral called hydrous ringwoodite (blue crystal). The crystal measures approximately 0.1 mm across and contains around one weight percent H2O in its crystal structure. At pressures corresponding to greater than 700 km depth (or over 400 miles below the surface), when heated with a laser (orange spots) a dehydration reaction occurred when ringwoodite transformed to higher pressure minerals. That dehydration reaction was then observed beneath North America by using seismic waves to image pockets of melt just below 700 km depth. This image relates to a paper that appeared in the 13 June, 2014, issue of Science, published by AAAS. The paper, by B. Schmandt at the University of New Mexico in Albuquerque, N.M., and colleagues was titled, "Dehydration melting at the top of the lower mantle." view more
Credit: [Credit: Steve Jacobsen / Northwestern University]