Ductile deformation during carbonation of serpentinized peridotite.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35710547.
- Also identified by DOI 10.1038/s41467-022-31049-1 and PMC identifier 9203755.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Carbonated serpentinites (listvenites) in the Samail Ophiolite, Oman, record mineralization of 1-2 Gt of CO<sub>2</sub>, but the mechanisms providing permeability for continued reactive fluid flow are unclear. Based on samples of the Oman Drilling Project, here we show that listvenites with a penetrative foliation have abundant microstructures indicating that the carbonation reaction occurred during deformation. Folded magnesite veins mark the onset of carbonation, followed by deformation during carbonate growth. Undeformed magnesite and quartz overgrowths indicate that deformation stopped before the reaction was completed. We propose deformation by dilatant granular flow and dissolution-precipitation assisted the reaction, while deformation in turn was localized in the weak reacting mass. Lithostatic pore pressures promoted this process, creating dilatant porosity for CO<sub>2</sub> transport and solid volume increase. This feedback mechanism may be common in serpentinite-bearing fault zones and the mantle wedge overlying subduction zones, allowing massive carbonation of mantle rocks.