Identification and measurement of neutron-absorbing elements on Mercury’s surface

Lawrence, D. J.; Feldman, W. C.; Goldsten, J.; McCoy, Timothy J.; Blewett, D. T.; Boynton, W. V.; Evans, L. G.; Nittler, L. R.; Rhodes, E. A.; Solomon, Sean C.

doi:10.1016/j.icarus.2010.04.005

Cited by 52 publications

(60 citation statements)

References 40 publications

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“…The inferred neutron absorption cross-section is broadly consistent with that produced by soils returned by the Luna 16, 20, and 24 missions, although the apparent lack of FeO in silicates at Mercury's surface led Lawrence et al (2010) to suggest a high abundance of Fe-Ti oxides, consistent with earlier interpretations of color observations (Denevi et al, 2009). If the observed neutron absorption is due to Fe and Ti in ilmenite, for instance, the NS data are consistent with ilmenite abundances of 7-18% (Lawrence et al, 2010). The GRS-derived upper bounds on Fe/Si and Ti/Si ratios are consistent with this range (Fig.…”

Section: Discussionsupporting

confidence: 81%

“…Fluxes of thermal neutrons measured by MESSENGER's NS during the three Mercury flybys (Lawrence et al, 2010) indicate a relatively high abundance of neutron-absorbing elements, interpreted as most likely consisting of some combination of Fe and Ti. The inferred neutron absorption cross-section is broadly consistent with that produced by soils returned by the Luna 16, 20, and 24 missions, although the apparent lack of FeO in silicates at Mercury's surface led Lawrence et al (2010) to suggest a high abundance of Fe-Ti oxides, consistent with earlier interpretations of color observations (Denevi et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…The GRS errors, although large, also allow for a similar (Taylor and Scott, 2004). Squares are lunar samples, including a ferroan anorthosite, FAN (Lawrence et al, 2010), and lunar meteorite MacAlpine Hills 88105 (MAC), a lunar anorthositic breccia (Jarosewich, 1990). Diamonds are calculated ratios for compositions with indicated abundances of ilmenite (wt%) and an assumed bulk Si abundance of 18 wt%.…”

Section: Discussionmentioning

confidence: 99%

“…As constrained by color and spectral observations of Mercury, the equilibrium and fractional crystallization models of Stockstill-Cahill and McCoy (2010) suggest that compositions based on those of lunar high-Ti picritic glasses (but with reduced FeO abundances) may be a possible starting magma composition for volcanic material on Mercury's surface. End products of such magmas must be capable of satisfying the lack of a spectral absorption feature attributable to FeO in Mercury's surface silicates (McClintock et al, 2008); the need for a spectrally neutral opaque phase as a constituent of intermediate terrain, lowreflectance blue plains, and low-reflectance material (Denevi et al, 2009); and the Feþ Ti abundances inferred from MESSENGER NS observations (Lawrence et al, 2010). High-Ti lunar picritic glasses have an average Si of 17.370.9% (Papike et al, 1998).…”

Section: Determination Of Elemental Abundances From Count Ratesmentioning

confidence: 99%

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Analysis of MESSENGER Gamma-Ray Spectrometer data from the Mercury flybys

Rhodes

Evans²,

Nittler

et al. 2011

Planetary and Space Science

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Determination Of Elemental Abundances From Count Ratesmentioning

confidence: 99%

See 2 more Smart Citations

Analysis of MESSENGER Gamma-Ray Spectrometer data from the Mercury flybys

Rhodes

Evans²,

Nittler

et al. 2011

Planetary and Space Science

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“…The low iron content confirms previous interpretations based on multispectral images (Blewett et al, 1997;McClintock et al, 2008) but the low titanium contents do not support a significant contribution by Ti-oxides in producing low-reflectance materials (Denevi et al, 2009;Riner et al, 2009Riner et al, , 2010Riner et al, , 2011Sprague et al, 2009;Lawrence et al, 2010). The SiO 2 content is high and ranges from 52 to 60 wt%.…”

Section: Calculations On An Oxide Basissupporting

confidence: 83%

Phase equilibria of ultramafic compositions on Mercury and the origin of the compositional dichotomy

Charlier

Grove

Zuber

2013

Earth and Planetary Science Letters

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a b s t r a c tMeasurements of major element ratios obtained by the MESSENGER spacecraft using x-ray fluorescence spectra are used to calculate absolute element abundances of lavas at the surface of Mercury. We discuss calculation methods and assumptions that take into account the distribution of major elements between silicate, metal, and sulfide components and the potential occurrence of sulfide minerals under reduced conditions. These first compositional data, which represent large areas of mixed highreflectance volcanic plains and low-reflectance materials and do not include the northern volcanic plains, share common silica-and magnesium-rich characteristics. They are most similar to terrestrial volcanic rocks known as basaltic komatiites. Two compositional groups are distinguished by the presence or absence of a clinopyroxene component. Melting experiments at one atmosphere on the average compositions of each of the two groups constrain the potential mineralogy at Mercury's surface, which should be dominated by orthopyroxene (protoenstatite and orthoenstatite), plagioclase, minor olivine if any, clinopyroxene (augite), and tridymite. The two compositional groups cannot be related to each other by any fractional crystallization process, suggesting differentiated source compositions for the two components and implying multi-stage differentiation and remelting processes for Mercury. Comparison with high-pressure phase equilibria supports partial melting at pressure o10 kbar, in agreement with last equilibration of the melts close to the crust-mantle boundary with two different mantle lithologies (harzburgite and lherzolite). Magma ocean crystallization followed by adiabatic decompression of mantle layers during cumulate overturn and/or convection would have produced adequate conditions to explain surface compositions. The surface of Mercury is not an unmodified quenched crust of primordial bulk planetary composition. Ultramafic lavas from Mercury have high liquidus temperatures (1450-1350 1C) and very low viscosities, in accordance with the eruption style characterized by flooding of pre-existing impact craters by lava and absence of central volcanoes.

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Detection and characterization of 0.5–8 MeV neutrons near Mercury: Evidence for a solar origin

et al. 2014

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[1] Data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Neutron Spectrometer (NS) have been used to identify energetic neutrons (0.5-8 MeV energy) associated with solar events that occurred on 4 June 2011. Multiple lines of evidence, including measurements from the NS and the MESSENGER Gamma-Ray Spectrometer, indicate that the detected neutrons have a solar origin. This evidence includes a lack of time-coincident, energetic (>45 MeV) charged particles that could otherwise create local neutrons from nearby spacecraft material and a lack of proton-induced gamma rays that should be seen if energetic protons were present. NS data cannot rule out the presence of lower-energy ions (<30 MeV) that can produce local neutrons. However, the ion spectral shape required to produce the measured neutron count rate locally is softer than any known ion spectral shape. The neutron energy spectrum shows a relative enhancement in the energy range 0.8-3 MeV compared with cosmic-ray-generated neutrons from the spacecraft or Mercury. The spectral shape of the measured neutron fluence spectrum is consistent with a previously modeled fluence spectrum of neutrons that originate at the Sun and are propagated through the MESSENGER spacecraft to the NS. These measurements provide strong evidence for a solar origin of the detected neutrons and suggest that a large number of low-energy threshold ion evaporation reactions were taking place on the Sun during the neutron event.

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Identification and measurement of neutron-absorbing elements on Mercury’s surface

Cited by 52 publications

References 40 publications

Analysis of MESSENGER Gamma-Ray Spectrometer data from the Mercury flybys

Analysis of MESSENGER Gamma-Ray Spectrometer data from the Mercury flybys

Phase equilibria of ultramafic compositions on Mercury and the origin of the compositional dichotomy

Detection and characterization of 0.5–8 MeV neutrons near Mercury: Evidence for a solar origin

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