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Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 466219 bytes)
GEOPHYSICAL RESEARCH LETTERS,
VOL. 35,
L07201,
doi:10.1029/2008GL033311,
2008
Non-ideal liquidus curve in the Fe-S system and Mercury's snowing core
Bin Chen
Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
Jie Li
Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
Steven A. Hauck II
Department of Geological Sciences, Case Western Reserve University, Cleveland, Ohio, USA
Abstract
We conducted multi-anvil experiments to investigate the melting behavior of the iron-sulfur system at moderate pressures.
Our data reveal a positive departure from ideal solution behavior at 14 GPa, as indicated by the presence of two inflection
points on the liquidus curve of iron-rich compositions. In contrast, the shape of the liquidus curve at 10 GPa is consistent
with nearly ideal mixing between end-member components. Combined with existing data at lower pressures and above 20 GPa, our
results suggest a negative liquidus temperature gradient under conditions found at shallow depths in Mercury's core. At the
present time, the core is most likely precipitating solid iron in the form of snow, at a single depth or in two distinct zones.
Formation and segregation of iron snow would alter the thermal and chemical state of the core and influence the origin and
surface expression of the planet's magnetic field.>
Received 21
January
2008;
accepted 5
March
2008;
published 3
April
2008.
Keywords: melting behavior;
Fe-S;
Mercury.
Index Terms: 1060 Geochemistry: Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008); 1507 Geomagnetism and Paleomagnetism: Core processes (1213, 8115); 6235 Planetary Sciences: Solar System Objects: Mercury; 3924 Mineral Physics: High-pressure behavior.
Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 466219 bytes)
Citation: Chen, B., J. Li, and S. A. Hauck II
(2008),
Non-ideal liquidus curve in the Fe-S system and Mercury's snowing core,
Geophys. Res. Lett.,
35,
L07201,
doi:10.1029/2008GL033311.
Copyright 2008 by the American Geophysical Union.
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