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摘要
In this study we performed high-temperature, dynamic (i.e. sinusoidal), three-point bending experiments of quartz single crystals and quartzite samples within the frequency range of seismic surveys (i.e. 0.1-20 Hz). At constant temperature close to the alpha-beta phase transition we observed a unique complex elastic behaviour of both quartz and quartzite. We find a frequency dependence of the complex Young's modulus of alpha-quartz, including a dissipation maximum at ae1 Hz supposedly related to the formation and variation of Dauphin, twin domains. Based on our experimental results for different crystallographic directions and additional modelling, we are able to describe the complex Young's modulus of quartz at its alpha-beta phase transition in a 3D diagram. We derive a frequency-dependent elasticity tensor, using a three-element equivalent circuit, composed of two springs E (1) and E (2) as well as a dashpot eta. E (1) and eta are connected parallel to each other, E (2) is added in series. Compliance coefficients yield (S (11)) E (1) = 572 GPa, E (2) = 70.0 GPa, eta = 64.6 GPa.s, (S (33)) E (1) = 127 GPa, E (2) = 52.1 GPa, eta = 22.9 GPa.s, (S (44)) E (1) = 204 GPa, E (2) = 37.5 GPa, eta = 26.4 GPa.s, (S (12)) E (1) = 612 GPa, E (2) = 106.7 GPa, eta = 78.5 GPa.s, (S (13)) E (1) = 1546 GPa, E (2) = 284 GPa, eta = 200 GPa.s; S (14) ae-0.0024 GPa(-1). We use the derived direction-dependent coefficients to predict the frequency-dependent complex elastic properties of isotropic polycrystalline quartz. These predictions agree well with the experimental results of the investigated quartzite. Finally, we explore the potential of using the anomalous frequency-dependent complex elastic properties of quartz at the alpha-beta phase transition that we observed as an in situ temperature probe for seismic studies of the Earth's continental crust.
- 出版日期2017-10
