Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)
This grant supports acquisition of an Infrared (IR) imaging microscope at Lamont Doherty Earth Observatory (LDEO) for research focused primarily on the measurement of water and carbon dioxide (CO2) in glasses and crystals. The instrument will support faculty and student research at Columbia University, the American Museum of Natural History, other universities in the region and high school teachers and students. Water and CO2 analysis is an increasingly important tool in research on volatile element effects on mantle processes, volcanic activity and the environment. Detailed understanding of the distribution and chemical behavior of water and carbon dioxide in a range of rock types and conditions will be enabled by the acquisition. Students will be trained in instrumental procedures and the instrument will serve regional institutions in the Mid-Atlantic states and New England. The acquisition will also support faculty outreach efforts to engage regional K-12 and community college students in societally relevant environmental and geohazards research. This support is congruent with NSF's mission of promoting the progress of science and advancing the national health, prosperity and welfare and training the next generation scientific workforce. The past years have seen a leap in understanding of the incorporation and diffusion of water in silicate minerals. Recent laboratory experiments have revealed infrared (IR) band-specific diffusivities in both clinopyroxene and olivine, meaning that the rate of water loss from a crystal depends on the specific defect that hosts H. Different defects can lose water at rates that vary over orders of magnitude. IR imaging becomes necessary to illuminate the zonation profiles for specific defects. Recent work finds pervasive H zonation profiles in volcanic crystals with rapid mapping, and potentially each crystal can tell its specific ascent history. Magma ascent rate is a parameter otherwise difficult to constrain, but one that may be critical to the vigor of eruption. Water zonation in minerals found in mantle xenoliths also records the timing of magma ascent and xenolith re-equilibration, essential for understanding the water content, and thus strength, of mantle lithosphere. IR imaging of water zonation in crystals and melts, at higher resolution and for greater populations of samples, has the capability to provide a new understanding of not only the volatile history of tectonic plates, but also the volatile budget, migration rate and explosive potential of magmas.