Diffusion of Noble Gases in Minerals

Abstract

The study of the diffusion of the six noble gas elements, helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) in minerals has spanned many decades with the primary geoscience focus on argon and helium (see below). The primary aim of this chapter is to acquaint the reader with the breadth of themes and perspectives that have accompanied the study of noble gas diffusion in minerals, and in addition, to attempt to bring the reader up to date with a focus on the most recent data and ideas from the literature of the past decade wherever possible. In this chapter, the available data for the diffusivity of each noble gas will be reviewed in turn, beginning with helium, then argon, followed by the rest of the gases. For specific minerals that have received considerably more attention than others, individual sections of this paper will be devoted to them. The data tables which accompany this chapter list the diffusion data cited herein; these tables are also available as an online supplement and from the author in excel format upon request. In general, every effort was made to compile all modern data where diffusivities have been quantified (i.e., where robust measurements of both activation energy and pre-exponential factor have been derived), though some early studies which have been superseded by more recent work will not be discussed. To begin, the first section describes the interpretive challenges associated with the most common method of observation for evaluation of noble gas diffusion in minerals: bulk degassing experiments. Then, following the review of the noble gas diffusion data, the remaining sections of the chapter focus on several broad themes that arise from the data that may span several noble gases or many minerals. The applicability of noble gases and noble gas …