Experimental investigation of the brittle-viscous transition in mafic rocks – Interplay between fracturing, reaction, and viscous deformation

Sina Marti; Holger Stünitz; Renée Heilbronner; Oliver Plumper; Martyn Drury

Experimental investigation of the brittle-viscous transition in mafic rocks – Interplay between fracturing, reaction, and viscous deformation

Sina Marti ¹ Holger Stünitz ^{2, 3, 4} Renée Heilbronner ¹ Oliver Plumper ⁵ Martyn Drury ⁵

1 Department of Environmental Sciences, University Basel

2 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327

3 Department of Geosciences

4 Géodynamique - UMR7327

BRGM - Bureau de Recherches Géologiques et Minières (BRGM), ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327 : UMR7327, INSU - CNRS - Institut national des sciences de l'Univers , UO - Université d'Orléans : UMR7327

5 Utrecht University [Utrecht]

Abstract : Rock deformation experiments are performed on fault gouge fabricated from ‘Maryland Diabase’ rock powder to investigate the transition from dominant brittle to dominant viscous behaviour. At the imposed strain rates of View the MathML sourceγ˙=3·10−5−3·10−6 s−1, the transition is observed in the temperature range of (600 °C < T < 800 °C) at confining pressures of (0.5 GPa ≤ Pc ≤ 1.5 GPa). The transition thereby takes place by a switch from brittle fracturing and cataclastic flow to viscous dissolution-precipitation creep and grain boundary sliding. Mineral reactions and resulting grain size refinement by nucleation are observed to be critical processes for the switch to viscous deformation, i.e., grain size sensitive creep. In the transitional regime, the mechanical response of the sample is a mixed-mode between brittle and viscous rheology and microstructures associated with both brittle and viscous deformation are observed. As grain size reduction by reaction and nucleation is a time dependent process, the brittle-viscous transition is not only a function of T but to a large extent also of microstructural evolution.

Keywords : Polyphase rheology Grain boundary sliding Rock deformation experiments Brittle-viscous transition Dissolution-precipitation

Document type :

Journal articles

Domain :

Sciences of the Universe [physics]

Complete list of metadatas

https://hal-insu.archives-ouvertes.fr/insu-01636815
Contributor : Nathalie Pothier <>
Submitted on : Friday, November 17, 2017 - 9:05:15 AM
Last modification on : Friday, May 10, 2019 - 1:54:18 PM

Experimental investigation of the brittle-viscous transition in mafic rocks – Interplay between fracturing, reaction, and viscous deformation

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Experimental investigation of the brittle-viscous transition in mafic rocks – Interplay between fracturing, reaction, and viscous deformation

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