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Low-Frequency Measurements of Seismic Moduli and Attenuation in Antigorite Serpentinite

David, EC; Brantut, N; Hansen, LN; Jackson, I; (2019) Low-Frequency Measurements of Seismic Moduli and Attenuation in Antigorite Serpentinite. Geophysical Research Letters , 46 (4) pp. 1993-2002. 10.1029/2018GL081271. Green open access

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Abstract

Laboratory measurements of seismic moduli and attenuation in antigorite serpentinite at a confining pressure of 200 MPa and temperatures up to 550 °C provide new results relevant to the interpretation of geophysical data in subduction zones. A polycrystalline antigorite specimen was tested via forced oscillations at small strain amplitudes and seismic frequencies (millihertz to hertz). The shear modulus has a temperature sensitivity, ∂G/∂T, averaging −0.017 GPa/K. Increasing temperature above 500 °C results in more intensive shear attenuation ( equation/grl58579-math-0001.png) and associated modulus dispersion, with equation/grl58579-math-0002.png increasing monotonically with increasing oscillation period and temperature. This “background” relaxation is adequately captured by a Burgers model for viscoelasticity and possibly results from intergranular mechanisms. Attenuation is higher in antigorite ( equation/grl58579-math-0003.png at 550 °C and 0.01 Hz) than in olivine ( equation/grl58579-math-0004.png below 800 °C), but such contrast does not appear to be strong enough to allow robust identification of antigorite from seismic models of attenuation only.

Type: Article
Title: Low-Frequency Measurements of Seismic Moduli and Attenuation in Antigorite Serpentinite
Open access status: An open access version is available from UCL Discovery
DOI: 10.1029/2018GL081271
Publisher version: https://doi.org/10.1029/2018GL081271
Language: English
Additional information: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. https://creativecommons.org/licenses/by/4.0/
Keywords: antigorite serpentinite, subduction zones, seismic velocity, seismic attenuation, viscoelastic relaxation
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/10071224
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