The ocean of water locked in the rocks of Earth’s mantle can influence geological processes such as melting and mineral deformation. Traditionally, researchers have used the mineral olivine to study the water in Earth’s upper mantle, but evolving technology has offered scientists the ability to use other minerals as well.
Warren and Hauri suggest using the mineral pyroxene to study water content of the mantle. The authors analyzed several samples of peridotite, a rock that contains both olivine and different types of pyroxenes, from continental and oceanic locations. The authors found that the pyroxene samples retained water content better than olivine, including those sampled from ocean trenches and ridges. As a result, the authors conclude that pyroxenes can be used to estimate the concentration and location of water bound in minerals in the upper mantle and can be “powerful tools” in investigating how the presence of water influences upper mantle processes such as deformation and melting. (Journal of Geophysical Research: Solid Earth, doi:10.1002/2013JB010328, 2014)
—JoAnna Wendel, Staff Writer