The August-September 2014 issue of American Mineralogist features three papers by, and of interest to, deep carbon scientists. In the first, Jun Wu and Peter Buseck from Arizona State University, USA, extend their previous work on carbon nanocontainers . To probe the effects of extreme temperature and pressure on the physical properties of carbon, the authors used transmission electron microscopy with near atomic resolution. Their experiments suggest a new means for storing carbon deep in Earth’s mantle.
DCO’s Sami Mikhail (Carnegie Institution of Washington, USA) and colleagues investigated a collection of diamondite samples to understand formation conditions of this carbon-rich mineral . The authors used infrared spectroscopy to probe sample nitrogen composition. The data suggest that mantle residence times among each diamondite sample vary considerably, pointing to multiple growth events distinct from those involved in diamond formation.
In the third paper, Codi Lazar (Carnegie Institution of Washington, USA) and colleagues, including DCO’s Craig Manning (UCLA, USA), describe the effects of decreasing oxygen fugacity at forearc conditions . With oxygen fugacity influencing carbon mobility in the mantle, it is important to understand the factors that cause it to change during processes such as subduction. Indeed, the authors show that despite the potential for graphite saturation, carbon may remain mobile in active subduction zones. Their work also has important implications for the study of abiotic methanogenesis, a process that may well be ubiquitous at subduction zones.
All three papers are currently featured as Notable Papers on the American Mineralogist website (25 August 2014).