Gardner, Joe 
ORCID: 0000-0002-8593-0201, Wheeler, John ORCID: 0000-0002-7576-4465 and Mariani, Elisabetta ORCID: 0000-0002-0585-5265
(2021)
Interactions between deformation and dissolution-precipitation reactions in plagioclase feldspar at greenschist facies.
Lithos, 396-39.
p. 106241.
|
Text
GardnerWheelerMariani2021.pdf - Author Accepted Manuscript Download (6MB) | Preview |
Abstract
Rocks often undergo deformation and metamorphism simultaneously. However, relatively little research has been carried out on the interactions between deformation, fluid influx and a recently identified type of metamorphic reaction, termed interface-coupled dissolution-precipitation. In this study, optical microscopy and electron backscatter diffraction (EBSD) were used to investigate the interactions between deformation and dissolution-precipitation reactions in feldspar from metagabbros deformed at mid-crustal conditions. Fracturing and fluid influx promoted two types of dissolution-precipitation reactions that worked in tandem to convert Ca-bearing plagioclase to pure albite. Conventional dissolution and precipitation, here defined as dissolution precipitation reactions involving a transport step, worked to heal fractures and produce fine-grained albite. In parts of original grains that were not fractured, interface-coupled dissolution-precipitation occurred to albitize mm-cm scale grain fragments. Because interface-coupled replacement displays fast kinetics, reaction fronts were not preserved, so coupled dissolution-precipitation was identified using the following microstructural criteria: a lack of preserved zoning, indicating a fast reaction mechanism; orientation inheritance during reaction indicating epitaxial nucleation/topotactic replacement; intracrystalline strain containing Burgers vectors that indicate distortion was not derived from crystal plasticity; intragranular microporosity and second phase inclusions which share orientations with twin and cleavage planes of their parent grains. These criteria could be applied to any system to identify interface-coupled replacement in the absence of preserved reaction fronts. Brittle fracturing and dissolution-precipitation resulted in an overall grain size reduction, and a transition from dominantly brittle to dominantly viscous deformation, producing mylonites at greenschist facies, and contributing to the development of a regional-scale shear zone.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Greenschist-facies deformation, Fluid-rock interaction, Dissolution-precipitation, Interface-coupled replacement reactions, Epitaxy, Electron backscatter diffraction |
| Divisions: | Faculty of Science and Engineering > School of Environmental Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 08 Jun 2021 14:48 |
| Last Modified: | 02 May 2023 10:47 |
| DOI: | 10.1016/j.lithos.2021.106241 |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3125593 |
Dimensions
Dimensions
