Selected elastic moduli of single-crystal olivines from ultrasonic experiments to mantle pressures

Science

Volumn 272, Issue 5264, 1996, Pages 979-980

  Chen, Ganglin ^a   Li, Baosheng ^a   Liebermann, Robert C ^a  

^a STONY BROOK UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; CHEMICAL ANALYSIS; PRESSURE MEASUREMENT; PRIORITY JOURNAL; SOIL; ULTRASOUND;

ELASTIC MODULUS; MANTLE; OLIVINE; P/T CONDITIONS;

EID: 0029768630     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.272.5264.979     Document Type: Article

References (15)

1. M. Kumazawa and O. L Anderson, J. Geophys. Res. 74, 5961 (1969).
2. E. K. Graham and G. R. Barsch, ibid., p. 5949.
3. T. S. Duffy and D. L. Anderson,ibid 94, 1895 (1989).
4. S. L. Webb, Phys. Chem. Minerals 16, 684 (1989).
5. J. M. Zaug et al., Science 260, 1487 (1993).
6. C. S. Duffy et al., Nature 378, 170 (1995).
7. C. S. Zha et al., J. Geophys. Res., in press.
8. A. Yoneda and M. Morioka, in High-Pressure Research: Application to Earth and Planetary Sciences, Y. Syono and M. H. Manghnani, Eds. (American Geophysical Union, Washington, DC, 1992), pp. 207-214.
9. B. Li et al., in preparation. For the ultrasonic measurements in the multi-anvil apparatus, the sample is surrounded by lead on the sides. On the bottom, it is backed by a Teflon disk (to enhance acoustic impedance mismatch) and then again by lead. The lead provides a pseudohydrostatic pressure environment and protects the sample from cracking at high pressures. Optical and transmission electron microscope (TEM) examination of the recovered sample after an experiment to a pressure P > 10 GPa revealed no cracks and no increase in the dislocation density, thereby demonstrating the absence of any significant deviatoric stress. To prevent the lead from extruding to the gasket area between the cubes while applying pressure, we inserted the sample and the surrounding lead into a steel sleeve. Bismuth and ZnTe, which were embedded in the Teflon disk backing the sample, served as in situ pressure markers because the change in their resistance with pressure could be monitored. Therefore, the pressure scale in each individual run could be obtained from the observed phase transformations in Bi (I to II, 2.55 GPa; III to V, 7.7 GPa) [M. Nomura et al., Jpn. J. Appl. Phys. 21, 936 (1982); E. C. Lloyd, Natl. Bur. Standards Spec. Publ. 326 (1971), pp. 1-3] and ZnTe (I, 9.6 GPa; II, 12.0 GPa) [K. Kusaba et al., Pure Appl. Geophys. (Schreiber Memorial Volume, R. C. Liebermann and C. H. Sondergeld, Eds.) 141, 644 (1993)]. The reproducibility of the cell pressure is better than 1% for the same ram force, and the pressure gradient is about 0.25 GPa/mm across the sample.
10. B. Li et al., in preparation. For the ultrasonic measurements in the multi-anvil apparatus, the sample is surrounded by lead on the sides. On the bottom, it is backed by a Teflon disk (to enhance acoustic impedance mismatch) and then again by lead. The lead provides a pseudohydrostatic pressure environment and protects the sample from cracking at high pressures. Optical and transmission electron microscope (TEM) examination of the recovered sample after an experiment to a pressure P > 10 GPa revealed no cracks and no increase in the dislocation density, thereby demonstrating the absence of any significant deviatoric stress. To prevent the lead from extruding to the gasket area between the cubes while applying pressure, we inserted the sample and the surrounding lead into a steel sleeve. Bismuth and ZnTe, which were embedded in the Teflon disk backing the sample, served as in situ pressure markers because the change in their resistance with pressure could be monitored. Therefore, the pressure scale in each individual run could be obtained from the observed phase transformations in Bi (I to II, 2.55 GPa; III to V, 7.7 GPa) [M. Nomura et al., Jpn. J. Appl. Phys. 21, 936 (1982); E. C. Lloyd, Natl. Bur. Standards Spec. Publ. 326 (1971), pp. 1-3] and ZnTe (I, 9.6 GPa; II, 12.0 GPa) [K. Kusaba et al., Pure Appl. Geophys. (Schreiber Memorial Volume, R. C. Liebermann and C. H. Sondergeld, Eds.) 141, 644 (1993)]. The reproducibility of the cell pressure is better than 1% for the same ram force, and the pressure gradient is about 0.25 GPa/mm across the sample.
11. B. Li et al., in preparation. For the ultrasonic measurements in the multi-anvil apparatus, the sample is surrounded by lead on the sides. On the bottom, it is backed by a Teflon disk (to enhance acoustic impedance mismatch) and then again by lead. The lead provides a pseudohydrostatic pressure environment and protects the sample from cracking at high pressures. Optical and transmission electron microscope (TEM) examination of the recovered sample after an experiment to a pressure P > 10 GPa revealed no cracks and no increase in the dislocation density, thereby demonstrating the absence of any significant deviatoric stress. To prevent the lead from extruding to the gasket area between the cubes while applying pressure, we inserted the sample and the surrounding lead into a steel sleeve. Bismuth and ZnTe, which were embedded in the Teflon disk backing the sample, served as in situ pressure markers because the change in their resistance with pressure could be monitored. Therefore, the pressure scale in each individual run could be obtained from the observed phase transformations in Bi (I to II, 2.55 GPa; III to V, 7.7 GPa) [M. Nomura et al., Jpn. J. Appl. Phys. 21, 936 (1982); E. C. Lloyd, Natl. Bur. Standards Spec. Publ. 326 (1971), pp. 1-3] and ZnTe (I, 9.6 GPa; II, 12.0 GPa) [K. Kusaba et al., Pure Appl. Geophys. (Schreiber Memorial Volume, R. C. Liebermann and C. H. Sondergeld, Eds.) 141, 644 (1993)]. The reproducibility of the cell pressure is better than 1% for the same ram force, and the pressure gradient is about 0.25 GPa/mm across the sample.
12. 3) was bonded to a truncated, stress-free corner of one of the tungsten carbide cubes, which served as an acoustic buffer rod and in addition transmitted pressure to the cell assembly. The sample was coupled to the buffer rod with a 2-μm gold foil.
13. 55 versus pressure by T. S. Duffy is based on the data in figure 1 of Zaug et al. (5).
14. W. A. Basset et al., in High-Pressure Research in Geophysics, S. Akimoto and M. H. Manghnani, Eds. (Center for Academic Publications, Tokyo, 1982), pp. 115-124.
15. We thank A. Yoneda for supplying the forsterite samples. We thank J. Ando who performed the TEM study on one of the recovered olivine samples to examine the dislocation density and helped to orient the San Carlos olivine samples. We thank T. Duffy and C. Zha who shared data on forsterite with us. Discussions with D. J. Weidner and Y. Wang led to improvements in this report. These high-pressure experiments were conducted in the Stony Brook High Pressure Laboratory, which is jointly supported by the State University of New York at Stony Brook and the NSF Science and Technology Center for High Pressure Research (EAR-89-20239). This research was also supported by EAR-93-04502. Mineral Physics Institute contribution 171.