Theoretical and experimental estimation of thermal effect on elastic property of Bt-rich rocks
Abstract
The compressional wave velocities (Vp) of mafic high-grade metamorphic rocks are measured under middle-lower continental crust conditions. Biotite-rich rocks display a strong decrease in Vpwith increasing temperature. These samples illustrated a change of Vp-anisotropy with increasing temperature. While biotite-Free rocks do not show obvious Vpchanges. These experimental results suggest a large effect of biotite on Vp and Vp-anisotropy with increasing temperature under middle-to lower crustal conditions. We try to estimate the effect of biotite on Vp by Molecular dynamics (MD) simulations under high temperature condition. The results of MD simulation indicate that elastic constants of biotite are strongly influenced by temperature. We also calculated whole rock velocity and anisotropy by using physical properties of single minerals (plagioclase, hornblende and estimated biotite and c rystallographic preferred orientation data of those minerals. Estimated Vp of biotite-rich rocks illustrated obvious decrease with increasing temperature. These estimations are well consistent with measured Vp changes under high temperature conditions. We conclude that the physical properties of biotite-rich rocks are strongly controlled by elastic constant of biotite and temperature.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMMR31B0078K
- Keywords:
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- 3909 Elasticity and anelasticity;
- MINERAL PHYSICS;
- 3924 High-pressure behavior;
- MINERAL PHYSICS;
- 5139 Transport properties;
- PHYSICAL PROPERTIES OF ROCKS;
- 8124 Earth's interior: composition and state;
- TECTONOPHYSICS