Limitations on silicon in the outer core: Ultrasonic measurements at high temperatures and high dK/dP values of Fe-Ni-Si liquids at high pressures

被引:9
作者
Williams, Quentin [1 ]
Manghnani, Murli H. [2 ]
Secco, Richard A. [3 ]
Fu, Shunsheng [2 ]
机构
[1] Univ Calif Santa Cruz, Dept Earth & Planetary Sci, Santa Cruz, CA 95064 USA
[2] Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Honolulu, HI USA
[3] Univ Western Ontario, Dept Earth Sci, London, ON, Canada
基金
美国国家科学基金会; 加拿大自然科学与工程研究理事会;
关键词
iron alloys; ultrasonics; liquid properties; core properties; EQUATION-OF-STATE; SOUND-VELOCITY MEASUREMENTS; EARTHS CORE; ISOTOPE FRACTIONATION; ALLOYS; IRON; DENSITY; METAL; SYSTEM; MODEL;
D O I
10.1002/2015JB012270
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
The sound velocities of four iron-nickel-silicon liquids (Fe-5wt%Ni-6wt%Si, Fe-5wt%Ni-10wt%Si, Fe-5wt%Ni-14wt%Si, and Fe-5wt%Ni-20wt%Si) are measured between 1460 and 1925K at ambient pressures using ultrasonic interferometry. The results constrain both the dependence on Si content of the bulk modulus of these liquids and the temperature dependence of their elasticity. These elastic data are utilized to assess both relatively low pressure (to 12GPa) compressional data on Fe-Si liquids and to extrapolate to higher-pressure and higher-temperature conditions. If a single equation of state for Fe-Ni-Si liquids of a given composition applies from low pressure to near core conditions, then our results imply that the isothermal pressure derivative of the bulk modulus of these liquids is high: likely 8 and above at high temperatures. This high value of the pressure derivative of the bulk modulus at low pressures in Fe-Si liquids causes marked stiffening at higher pressures, leading to notable incompressibility and apparent low values of the pressure derivative of the bulk modulus at core conditions. These results reinforce the conclusion that silicon is not a major alloying component of Earth's core.
引用
收藏
页码:6846 / 6855
页数:10
相关论文
共 60 条
[1]   AN EQUATION OF STATE FOR LIQUID-IRON AND IMPLICATIONS FOR THE EARTHS CORE [J].
ANDERSON, WW ;
AHRENS, TJ .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1994, 99 (B3) :4273-4284
[2]   Silicon isotopes in meteorites and planetary core formation [J].
Armytage, R. M. G. ;
Georg, R. B. ;
Savage, P. S. ;
Williams, H. M. ;
Halliday, A. N. .
GEOCHIMICA ET COSMOCHIMICA ACTA, 2011, 75 (13) :3662-3676
[3]   Shock compression of liquid silicates to 125 GPa: The anorthite-diopside join [J].
Asimow, Paul D. ;
Ahrens, Thomas J. .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2010, 115
[4]   Reference data for the density and viscosity of liquid aluminum and liquid iron [J].
Assael, MJ ;
Kakosimos, K ;
Banish, RM ;
Brillo, J ;
Egry, I ;
Brooks, R ;
Quested, PN ;
Mills, KC ;
Nagashima, A ;
Sato, Y ;
Wakeham, WA .
JOURNAL OF PHYSICAL AND CHEMICAL REFERENCE DATA, 2006, 35 (01) :285-300
[5]   A seismologically consistent compositional model of Earth's core [J].
Badro, James ;
Cote, Alexander S. ;
Brodholt, John P. .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2014, 111 (21) :7542-7545
[6]   SHOCK COMPRESSION OF 2 IRON-SILICON ALLOYS TO 2.7 MEGABARS [J].
BALCHAN, AS ;
COWAN, GR .
JOURNAL OF GEOPHYSICAL RESEARCH, 1966, 71 (14) :3577-+
[7]   Estimation of the Thermodynamic Characteristics of the Earth's Core Using the Embedded Atom Model [J].
Belashchenko, D. K. .
GEOCHEMISTRY INTERNATIONAL, 2014, 52 (06) :456-466
[8]   FINITE STRAIN ISOTHERM AND VELOCITIES FOR SINGLE-CRYSTAL AND POLYCRYSTALLINE NACL AT HIGH-PRESSURES AND 300-DEGREE-K [J].
BIRCH, F .
JOURNAL OF GEOPHYSICAL RESEARCH, 1978, 83 (NB3) :1257-1268
[9]   Thermal Evolution and Magnetic Field Generation in Terrestrial Planets and Satellites [J].
Breuer, Doris ;
Labrosse, Stephane ;
Spohn, Tilman .
SPACE SCIENCE REVIEWS, 2010, 152 (1-4) :449-500
[10]   PHASE-TRANSITIONS, GRUNEISEN-PARAMETER, AND ELASTICITY FOR SHOCKED IRON BETWEEN 77-GPA AND 400-GPA [J].
BROWN, JM ;
MCQUEEN, RG .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1986, 91 (B7) :7485-7494