Castagna, A;
Ougier-Simonin, A;
Benson, PM;
Browning, J;
Walker, RJ;
Fazio, M;
Vinciguerra, S;
(2018)
Thermal Damage and Pore Pressure Effects of the Brittle‐Ductile Transition in Comiso Limestone.
Journal of Geophysical Research: Solid Earth
, 123
(9)
pp. 7644-7660.
10.1029/2017JB015105.
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Abstract
Volcanic edifices are commonly unstable, with magmatic and non‐magmatic fluid circulation, and elevated temperature gradients having influence on the mechanical strength of edifice and basement rocks. We present new mechanical characterization of the Comiso limestone of the Mount Etna Volcano (Italy) basement to constrain the effects of regional ambient conditions associated with the volcanic system: the effects of pore fluid on rock strength and the effects of distal magmatic heating (~20 °C to 600 °C) at a range of simulated depths (0.2 to 2.0 km). The presence of water promotes ductile behaviour at shallow depths and causes a significant reduction in brittle rock strength compared to dry conditions. Thermal stressing, in which specimens were heated and cooled before mechanical testing at room temperature, has a variable effect for dry and saturated cases. In dry conditions, thermal stressing up to 450 °C homogenizes the strength of the specimen such that the majority of the specimens exhibit the same peak stress; at 600 °C, the brittle failure is promoted at lower differential stress. The presence of water in thermally‐stressed specimens promotes ductile behaviour and reduces peak strength. Acoustic emission monitoring suggests that accumulated damage is associated with the heating–cooling sequence, particularly in the 300–450‐600°C. Based on conduction modeling, we estimate this temperature range could affect basement rocks up to 300 m away from minor sheet intrusions and much further with larger bodies. Considering the dyke spacing beneath Etna, these conditions may apply to a significant percentage of the basement, promoting ductile behaviour at relatively shallow depths.
| Type: | Article |
|---|---|
| Title: | Thermal Damage and Pore Pressure Effects of the Brittle‐Ductile Transition in Comiso Limestone |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1029/2017JB015105 |
| Publisher version: | https://doi.org/10.1029/2017JB015105 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Carbonates, Thermal treatment, Mechanical strength, Triaxial experiments, Pore fluid pressure, Ultrasonic wave velocities |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10094982 |
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