Melting relations in the iron-sulfur system at ultra-high pressures: Implications for the thermal state of the earth
- Univ. of California, Berkeley (USA)
The melting temperatures of FeS-troilite and of a 10 wt % sulfur iron alloy have been measured to pressures of 120 and 90 GPa, respectively. Results document that FeS melts at a temperature of 4,100 ({plus minus}300) K at the pressure of the core-mantle boundary. Eutectic-like behavior persists in the iron-sulfur system to the highest pressures of the measurements, in marked contrast to the solid-solution-like behavior observed at high pressures in the iron-iron oxide system. Iron with 10 wt % sulfur melts at a similar temperature as FeS at core-mantle boundary conditions. If the sole alloying elements of iron within the core are sulfur and oxygen and the outer core is entirely liquid, the minimum temperature at the top of the outer core is 4,900 ({plus minus}400) K. Calculations of mantle geotherms dictate that there must be a temperature increase of between 1,000 and 2,000 K across thermal boundary layers within the mantle. If D{double prime} is compositionally stratified, it could accomodate the bulk of this temperature jump.
- OSTI ID:
- 5320108
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 95:B12; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EARTH MANTLE
THERMODYNAMIC PROPERTIES
IRON BASE ALLOYS
MELTING POINTS
IRON SULFIDES
TROILITE
BOUNDARY CONDITIONS
EARTH CORE
PRESSURE DEPENDENCE
STRATIFICATION
SULFUR COMPOUNDS
TEMPERATURE GRADIENTS
ULTRAHIGH TEMPERATURE
VERY HIGH PRESSURE
ALLOYS
CHALCOGENIDES
IRON ALLOYS
IRON COMPOUNDS
MINERALS
PHYSICAL PROPERTIES
PYRRHOTITE
SULFIDE MINERALS
SULFIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
580000* - Geosciences