TEMPERATURES IN THE EARTHS CORE FROM MELTING-POINT MEASUREMENTS OF IRON AT HIGH STATIC PRESSURES

被引:525
作者
BOEHLER, R
机构
[1] Max-Planck-Institut für Chemie, 6500 Mainz
关键词
D O I
10.1038/363534a0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
THE temperature distribution in the Earth's core places important constraints on the Earth's internal heat budget and on models of the geodynamo. The solid inner core crystallizes from a liquid outer core, consisting mainly of iron alloyed with a lighter element, at a depth of about 5,100 km (corresponding to a pressure of about 3.3 Mbar). Thus, the most reliable means of determining the temperature gradient in the core is to estimate the melting temperature of iron and iron-rich compounds at the pressure of the inner core boundary. Current estimates range from about 4,000 to 8,000 K; but these estimates, obtained from shock compression1-3, theory (discussed in ref. 4) and extrapolation of static pressure data2,3,5 are poorly constrained. Here I present melting-point measurements on iron and iron-oxygen compounds at static pressures of up to 2 Mbar. Extrapolation of these results to 3.3 Mbar yields a temperature at the inner-core boundary of 4,850+/-200 K. A weak change in optical absorption observed above 2,000 K may correspond to the solid-solid phase transition found in shock experiments at 2 Mbar (ref. 1).
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页码:534 / 536
页数:3
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