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Extrapolation of bulk rock elastic moduli of different rock types to high pressure conditions and comparison with texture-derived elastic moduli
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SYSNO ASEP 0490796 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Extrapolation of bulk rock elastic moduli of different rock types to high pressure conditions and comparison with texture-derived elastic moduli Tvůrce(i) Ullemeyer, K. (DE)
Lokajíček, Tomáš (GLU-S) RID, SAI, ORCID
Vasin, R.N. (RU)
Keppler, R. (DE)
Behrmann, J. H. (DE)Zdroj.dok. Physics of the Earth and Planetary Interiors. - : Elsevier - ISSN 0031-9201
Roč. 275, FEB 2018 (2018), s. 32-43Poč.str. 12 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. NL - Nizozemsko Klíč. slova anisotropy ; calcite ; crystallography ; elastic moduli ; elasticity ; extrapolation ; marble ; neutron diffraction ; rock pressure ; seismic waves ; Shear waves ; single crystals ; structural geology ; velocity Vědní obor RIV DB - Geologie a mineralogie Obor OECD Geology CEP GA13-13967S GA ČR - Grantová agentura ČR GA16-03950S GA ČR - Grantová agentura ČR Institucionální podpora GLU-S - RVO:67985831 UT WOS 000425070400004 EID SCOPUS 85044668142 DOI 10.1016/j.pepi.2018.01.001 Anotace In this study elastic moduli of three different rock types of simple (calcite marble) and more complex (amphibolite, micaschist) mineralogical compositions were determined by modeling of elastic moduli using texture (crystallographic preferred orientation, CPO) data, experimental investigation and extrapolation. 3D models were calculated using single crystal elastic moduli, and CPO measured using time-of-flight neutron diffraction at the SKAT diffractometer in Dubna (Russia) and subsequently analyzed using Rietveld Texture Analysis. To define extrinsic factors influencing elastic behaviour, P-wave and S-wave velocity anisotropies were experimentally determined at 200, 400 and 600 MPa confining pressure. Functions describing variations of the elastic moduli with confining pressure were then used to predict elastic properties at 1000 MPa, revealing anisotropies in a supposedly crack-free medium. In the calcite marble elastic anisotropy is dominated by the CPO. Velocities continuously increase, while anisotropies decrease from measured, over extrapolated to CPO derived data. Differences in velocity patterns with sample orientation suggest that the foliation forms an important mechanical anisotropy. The amphibolite sample shows similar magnitudes of extrapolated and CPO derived velocities, however the pattern of CPO derived velocity is closer to that measured at 200 MPa. Anisotropy decreases from the extrapolated to the CPO derived data. In the micaschist, velocities are higher and anisotropies are lower in the extrapolated data, in comparison to the data from measurements at lower pressures. Generally our results show that predictions for the elastic behavior of rocks at great depths are possible based on experimental data and those computed from CPO. The elastic properties of the lower crust can, thus, be characterized with an improved degree of confidence using extrapolations. Anisotropically distributed spherical micro-pores are likely to be preserved, affecting seismic velocity distributions. Compositional variations in the polyphase rock samples do not significantly change the velocity patterns, allowing the use of RTA-derived volume percentages for the modeling of elastic moduli. Pracoviště Geologický ústav Kontakt Jana Popelková, popelkova@gli.cas.cz, Sabina Janíčková, Tel.: 233 087 272 Rok sběru 2019
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