TY - JOUR
T1 - Nature of opaque components on Mercury
T2 - Insights into a Mercurian magma ocean
AU - Riner, M. A.
AU - Lucey, P. G.
AU - Desch, Steven
AU - McCubbin, F. M.
PY - 2009/1/28
Y1 - 2009/1/28
N2 - Analysis of Mariner 10 and MESSENGER data sets reveal the importance of opaque components on Mercury's surface. A global darkening agent, suggested to be ilmenite or other Fe-, Ti-bearing opaque mineral, has been invoked to explain the lower albedo of Mercury relative to the lunar highlands. Separately, a low-reflectance material (LRM) has been recognized as one of three dominant color terrains. We present laboratory reflectance spectra of ilmenite size separates and other candidate Fe-, Ti-bearing oxide minerals. These oxides cannot sufficiently darken Mercury without violating neutron spectrometer constraints on surface iron content. The spectra of all samples exhibit negative spectral slopes shortward of 500 nm, consistent with the LRM. We review models of crystallization of an FeO-poor Mercurian magma ocean and show that lack of a plagioclase flotation crust could lead to a thin quench crust with near surface layers of incompatible- and Ti-rich late stage cumulates, consistent with Mercury's albedo and LRM.
AB - Analysis of Mariner 10 and MESSENGER data sets reveal the importance of opaque components on Mercury's surface. A global darkening agent, suggested to be ilmenite or other Fe-, Ti-bearing opaque mineral, has been invoked to explain the lower albedo of Mercury relative to the lunar highlands. Separately, a low-reflectance material (LRM) has been recognized as one of three dominant color terrains. We present laboratory reflectance spectra of ilmenite size separates and other candidate Fe-, Ti-bearing oxide minerals. These oxides cannot sufficiently darken Mercury without violating neutron spectrometer constraints on surface iron content. The spectra of all samples exhibit negative spectral slopes shortward of 500 nm, consistent with the LRM. We review models of crystallization of an FeO-poor Mercurian magma ocean and show that lack of a plagioclase flotation crust could lead to a thin quench crust with near surface layers of incompatible- and Ti-rich late stage cumulates, consistent with Mercury's albedo and LRM.
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U2 - 10.1029/2008GL036128
DO - 10.1029/2008GL036128
M3 - Article
AN - SCOPUS:62749166456
VL - 36
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 2
M1 - L02201
ER -