Cara Vennari

Cara Vennari is an NSF EAR Postdoctoral Fellow who studies the physical and chemical behavior of the mantle. Specifically, she studies how volatile elements (e.g., carbon, hydrogen, nitrogen) affect the Earth’s mantle. By conducting high pressure and temperature experiments, she can simulate the extreme conditions present in the mantle (pressure range of 0 to 135 GPa and temperature from 0 to ~4000 K). She investigates how bonding, the structure of solid phases, and melt composition/generation changes at these extreme conditions. In a recent paper, she investigated the structural changes to the carbonate ion to high pressures using Raman spectroscopy. In this paper, she observed an intermediate coordination between 3- and 4-fold coordination of the carbonate ion: this distortion is indicative of a change to the behavior of carbonate ions in the deep Earth. With an increase in coordination number for the carbonate ion, carbonatite (carbon-rich) magmas are more likely to be higher viscosity at depth, and hence carbon might have a longer residence time in the mantle than previously thought.