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| Titel |
Thermal damage in Westerly granite investigated by means of Synchrotron radiation based microtomography |
| VerfasserIn |
F. Fusseis, C. E. Schrank, J. Liu |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067244
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| Zusammenfassung |
| During heating of rocks, material- and orientation induced differences in the thermal expansivity and elastic behavior cause mismatch and heterogeneous stresses between expanding grains. Given sufficient heating, these thermal-elastic stresses cause inelastic deformation, mostly extensive cracking. A special case of thermally induced deformation in natural rocks is the decrepitation of fluid inclusions.
Westerly granite, from Maine (USA) is often used as ’model granite’ in rock deformation experiments. A number of these experiments investigate the effects of heating on the granite’s bulk properties, in particular its strength, elastic properties, and permeability (e.g., Fredrich & Wong, 1986, Wang et al., 1989, Nasseri et al., 2007). Most thermally induced deformation is ascribed to the formation of grain boundary- and intragranular cracks. The contribution of decrepitating fluid inclusions is rarely considered (Hall & Bodnar, 1989). The relative importance of both deformation processes remains to be quantified.
This contribution reports on a heating experiment conducted inside a microtomograph at sector 2-BM at the Advanced Photon Source (USA). We heated an unconfined 1 mm diameter, 8 mm long cylinder of Westerly granite in 15 K intervals from room temperature to 668 K. During heating, we acquired 26 three-dimensional microtomographic datasets documenting the evolution of the sample over the entire temperature span with sub-micron resolution. These data permit the most detailed temperature-resolved documentation of thermal cracking and fluid inclusion decrepitation to date. We examine (a) how absolute temperature affects the mechanisms by which thermal damage is accommodated in Westerly granite; (b) the evolution of geometrical characteristics of thermal damage; and (c) the effects of a retrograde overprint on deformation localisation.
Fredrich & Wong (1986), JGR 91/B12, 12743-12764.
Hall & Bodnar (1989), Tectonophysics 168, 283-296.
Nasseri et al. (2007), Int J Rock Mech Min Sci, 44/4, 601-616.
Wang et al. (1989), JGR 94/B2, 1745-1758. |
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