scholarly journals Sharp and seismically transparent inner core boundary region revealed by an entire network observation of near-vertical PKiKP

2006 ◽  
Vol 58 (7) ◽  
pp. 855-863 ◽  
Author(s):  
Hitoshi Kawakatsu
Keyword(s):  
Inner Core ◽  
Boundary Region ◽  
Network Observation ◽  
Core Boundary ◽  
Entire Network

Measuring the melting curve of iron at super-Earth core conditions

Science ◽  
2022 ◽  
Vol 375 (6577) ◽  
pp. 202-205
Author(s):  
Richard G. Kraus ◽  
Russell J. Hemley ◽  
Suzanne J. Ali ◽  
Jonathan L. Belof ◽  
Lorin X. Benedict ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Inner Core ◽  
Melting Curve ◽  
Radiation Shielding ◽  
Metal Core ◽  
Earth Core ◽  
Core Boundary ◽  
Earth Like Planets ◽  
Earth’S Inner Core ◽  
Core Conditions

Terapascal iron-melting temperature The pressure and temperature conditions at which iron melts are important for terrestrial planets because they determine the size of the liquid metal core, an important factor for understanding the potential for generating a radiation-shielding magnetic field. Kraus et al . used laser-driven shock to determine the iron-melt curve up to a pressure of 1000 gigapascals (see the Perspective by Zhang and Lin). This value is about three times that of the Earth’s inner core boundary. The authors found that the liquid metal core lasted the longest for Earth-like planets four to six times larger in mass than the Earth. —BG

scholarly journals Melting of iron determined by X-ray absorption spectroscopy to 100 GPa

2015 ◽  
Vol 112 (39) ◽  
pp. 12042-12045 ◽  
Author(s):  
Giuliana Aquilanti ◽  
Angela Trapananti ◽  
Amol Karandikar ◽  
Innokenty Kantor ◽  
Carlo Marini ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Absorption Spectroscopy ◽  
Inner Core ◽  
Solid Phase ◽  
Melting Curve ◽  
X Ray ◽  
Core Boundary ◽  
Diamond Anvil ◽  
Laser Heated ◽  
X Ray Absorption

Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa.

Revised velocities in the Earth's core

1973 ◽  
Vol 63 (3) ◽  
pp. 1073-1105 ◽  
Author(s):  
Anthony Qamar
Keyword(s):  
Transition Zone ◽  
Inner Core ◽  
Velocity Model ◽  
Outer Core ◽  
Travel Times ◽  
Zone Boundary ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Core Boundary ◽  
Velocity Jump

abstract Travel times and amplitudes of PKP and PKKP from three earthquakes and four underground nuclear explosions are presented. Observations of reflected core waves at nearly normal angles of incidence provide new constraints on the average velocities in the inner and outer core. Interpretation of these data suggests that several small but significant changes to Bolt's (1962) core velocity model (T2) are necessary. A revised velocity model KOR5 is given together with the derived travel times that are consistent with the 1968 tables for P. Model KOR5 possesses a velocity in the transition zone which is 112 per cent lower than that in model T2. In addition, KOR5 has a velocity jump at the transition zone boundary (r = 1782 km) of 0.013 km/sec and a jump at the inner core boundary (r = 1213 km) of 0.6 km/sec. These values are, respectively, 1/20 and 2/3 of the corresponding model T2 values.

Melting in the Fe-FeO system to 204 GPa: Implications for oxygen in Earth's core

2019 ◽  
Vol 104 (11) ◽  
pp. 1603-1607 ◽  
Author(s):  
Kenta Oka ◽  
Kei Hirose ◽  
Shoh Tagawa ◽  
Yuto Kidokoro ◽  
Yoichi Nakajima ◽  
...  
Keyword(s):  
Inner Core ◽  
Liquid Core ◽  
Light Element ◽  
Liquid Immiscibility ◽  
Eutectic Liquid ◽  
Core Boundary ◽  
Diamond Anvil ◽  
Rich Liquid ◽  
Melting Experiments ◽  
Carbon Concentrations

Abstract We performed melting experiments on Fe-O alloys up to 204 GPa and 3500 K in a diamond-anvil cell (DAC) and determined the liquidus phase relations in the Fe-FeO system based on textural and chemical characterizations of recovered samples. Liquid-liquid immiscibility was observed up to 29 GPa. Oxygen concentration in eutectic liquid increased from >8 wt% O at 44 GPa to 13 wt% at 204 GPa and is extrapolated to be about 15 wt% at the inner core boundary (ICB) conditions. These results support O-rich liquid core, although oxygen cannot be a single core light element. We estimated the range of possible liquid core compositions in Fe-O-Si-C-S and found that the upper bounds for silicon and carbon concentrations are constrained by the crystallization of dense inner core at the ICB.

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