Mineral reaction kinetics constrain the length scale of rock matrix diffusion

Wogelius, R.A.; Milodowski, A.E.; Field, L.P.; Metcalfe, R.; Lowe, T.; van Veelen, A.; Carpenter, G.; Norris, S.; Yardley, B.. 2020 Mineral reaction kinetics constrain the length scale of rock matrix diffusion. Scientific Reports, 10 (1), 8142. https://doi.org/10.1038/s41598-020-65113-x

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Official URL: http://dx.doi.org/10.1038/s41598-020-65113-x

Abstract/Summary

Mass transport by aqueous fluids is a dynamic process in shallow crustal systems, redistributing nutrients as well as contaminants. Rock matrix diffusion into fractures (void space) within crystalline rock has been postulated to play an important role in the transient storage of solutes. The reacted volume of host rock involved, however, will be controlled by fluid-rock reactions. Here we present the results of a study which focusses on defining the length scale over which rock matrix diffusion operates within crystalline rock over timescales that are relevant to safety assessment of radioactive and other long-lived wastes. Through detailed chemical and structural analysis of natural specimens sampled at depth from an active system (Toki Granite, Japan), we show that, contrary to commonly proposed models, the length scale of rock matrix diffusion may be extremely small, on the order of centimetres, even over timescales of millions of years. This implies that in many cases the importance of rock matrix diffusion will be minimal. Additional analyses of a contrasting crystalline rock system (Carnmenellis Granite, UK) corroborate these results.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1038/s41598-020-65113-x
ISSN:	2045-2322
Date made live:	08 Jun 2020 14:54 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/527892

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1038/s41598-020-65113-x

ISSN:

2045-2322

Date made live:

08 Jun 2020 14:54 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/527892