Nitrogen Diffusion in Calcite

Abstract

Diffusion of N has been measured in natural calcite. For diffusion normal to the {10Ī4} cleavage surface, an activation energy for diffusion of 222 ± 17 kJ mol-1 and pre-exponential factor of 1.92 × 10-9 m 2 sec-1 are obtained. Diffusion parallel to c is slightly faster than diffusion normal to {10Ī4}. These data indicate that N contained in inclusions in calcite will diffuse through the calcite lattice at Earth's upper crustal and surface conditions slowly enough so that calcite may faithfully retain a passive signature of its formation environment for billions of years, providing much needed insight into the cycling of nitrogen between atmosphere, crust, and mantle.