Mineral dissolution and reprecipitation mediated by an amorphous phase
Journal article, 2018

Fluid-mediated mineral dissolution and reprecipitation processes are the most common mineral reaction mechanism in the solid Earth and are fundamental for the Earth's internal dynamics. Element exchange during such mineral reactions is commonly thought to occur via aqueous solutions with the mineral solubility in the coexisting fluid being a rate limiting factor. Here we show in high-pressure/low temperature rocks that element transfer during mineral dissolution and reprecipitation can occur in an alkali-Al-Si-rich amorphous material that forms directly by depolymerization of the crystal lattice and is thermodynamically decoupled from aqueous solutions. Depolymerization starts along grain boundaries and crystal lattice defects that serve as element exchange pathways and are sites of porosity formation. The resulting amorphous material occupies large volumes in an interconnected porosity network. Precipitation of product minerals occurs directly by repolymerization of the amorphous material at the product surface. This mechanism allows for significantly higher element transport and mineral reaction rates than aqueous solutions with major implications for the role of mineral reactions in the dynamic Earth.

Author

Matthias Konrad-Schmolke

University of Gothenburg

Ralf Halama

Keele University

Richard Wirth

German Research Centre for Geosciences (GFZ)

Aurélien Thomen

Chalmers, Chemistry and Chemical Engineering

Nico Klitscher

German Research Centre for Geosciences (GFZ)

Luiz Morales

Swiss Federal Institute of Technology in Zürich (ETH)

Anja Schreiber

German Research Centre for Geosciences (GFZ)

Franziska D.H. Wilke

German Research Centre for Geosciences (GFZ)

Nature Communications

2041-1723 (ISSN)

Vol. 9 1 1637

Subject Categories

Mineral and Mine Engineering

Inorganic Chemistry

Geochemistry

DOI

10.1038/s41467-018-03944-z

More information

Latest update

1/16/2019