Origin, Internal Structure and Evolution of 4 Vesta

Zuber, M. T.; McSween, H. Y.; Binzel, Richard P.; Elkins-Tanton, Linda T.; Konopliv, Alexander S.; Pieters, C. M.; Smith, David E.

doi:10.1007/978-1-4614-4903-4_6

Cited by 3 publications

(3 citation statements)

References 91 publications

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“…In addition, it is difficult to understand how a Vesta-like object could retain sufficient heat to create secondary melting and near-surface extrusions of lava late enough in Vesta's evolution for the flows or major parts of them to survive impact battering into the present day (e.g. Zuber et al, 2011;McSween et al, 2011;Russell et al, 2012Russell et al, , 2013. On the other hand, there is morphological evidence of impact melt deposits on Vesta that have low reflectance (Denevi et al, 2012;Yingst et al, 2014;Williams et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The geological nature of dark material on Vesta and implications for the subsurface structure

Jaumann

Naß

Otto

et al. 2014

Icarus

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a b s t r a c tDeposits of dark material appear on Vesta's surface as features of relatively low-albedo in the visible wavelength range of Dawn's camera and spectrometer. Mixed with the regolith and partially excavated by younger impacts, the material is exposed as individual layered outcrops in crater walls or ejecta patches, having been uncovered and broken up by the impact. Dark fans on crater walls and dark deposits on crater floors are the result of gravity-driven mass wasting triggered by steep slopes and impact seismicity. The fact that dark material is mixed with impact ejecta indicates that it has been processed together with the ejected material. Some small craters display continuous dark ejecta similar to lunar dark-halo impact craters, indicating that the impact excavated the material from beneath a higher-albedo surface. The asymmetric distribution of dark material in impact craters and ejecta suggests non-continuous distribution in the local subsurface. Some positive-relief dark edifices appear to be impact-sculpted hills with dark material distributed over the hill slopes. Dark features inside and outside of craters are in some places arranged as linear outcrops along scarps or as dark streaks perpendicular to the local topography. The spectral characteristics of the dark material resemble that of Vesta's regolith. Dark material is distributed unevenly across Vesta's surface with clusters of all types of dark material exposures. On a local scale, some craters expose or are associated with dark material, while others in the immediate vicinity do not show evidence for dark material. While the variety of surface exposures of dark material and their different geological correlations with surface features, as well as their uneven distribution, indicate a globally inhomogeneous distribution in the subsurface, the dark material seems to be correlated with the rim and ejecta of the older Veneneia south polar basin structure. The origin of the dark material is still being debated, however, the geological analysis suggests that it is exogenic, from carbon-rich low-velocity impactors, rather than endogenic, from freshly exposed mafic material or melt, exposed or created by impacts.

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Section: Introductionmentioning

confidence: 99%

The geological nature of dark material on Vesta and implications for the subsurface structure

Jaumann

Naß

Otto

et al. 2014

Icarus

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“…Asteroids are considered to be remnants of such planetesimals. Asteroid 4 Vesta, which is the second largest in the asteroid belt with a radius of $250 km, is widely believed to be the parent body of howardite-eucrite-diogenite (HED) achondrites (e.g., Ruzicka et al, 1997) and is known as a differentiated object with a basaltic surface composition and central metallic core (e.g., Zuber et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Wetting property of Fe‐S melt in solid core: Implication for the core crystallization process in planetesimals

Matsubara,

Terasaki,

Yoshino

et al. 2024

Meteorit & Planetary Scien

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In differentiated planetesimals, the liquid core starts to crystallize during secular cooling, followed by the separation of liquid–solid phases in the core. The wetting property between liquid and solid iron alloys determines whether the core melts are trapped in the solid core or they can separate from the solid core during core crystallization. In this study, we performed high‐pressure experiments under the conditions of the interior of small bodies (0.5–3.0 GPa) to study the wetting property (dihedral angle) between solid Fe and liquid Fe‐S as a function of pressure and duration. The measured dihedral angles are approximately constant after 2 h and decrease with increasing pressure. The dihedral angles range from 30° to 48°, which are below the percolation threshold of 60° at 0.5–3.0 GPa. The oxygen content in the melt decreases with increasing pressure and there are strong positive correlations between the S + O or O content and the dihedral angle. Therefore, the change in the dihedral angle is likely controlled by the O content of the Fe‐S melt, and the dihedral angle tends to decrease with decreasing O content in the Fe‐S melt. Consequently, the Fe‐S melt can form interconnected networks in the solid core. In the obtained range of the dihedral angle, a certain amount of the Fe‐S melt can stably coexist with solid Fe, which would correspond to the “trapped melt” in iron meteorites. Excess amounts of the melt would migrate from the solid core over a long period of core crystallization in planetesimals.

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“…Asteroid 4 Vesta is the second most massive body in the asteroid belt and is the only largely preserved asteroid that has a fully differentiated core, mantle, and basaltic crust (Zuber et al 2011). Despite its relatively small size (r = 263 km; Russell et al 2012), 4 Vesta is an excellent proxy to allow understanding of early magmatism and differentiation processes occurring on planets and moons.…”

Section: Introductionmentioning

confidence: 99%

End of magmatism in the upper crust of asteroid 4 Vesta

Jourdan

Forman

Kennedy

et al. 2021

Meteorit & Planetary Scien

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Asteroid 4 Vesta is the only largely preserved differentiated asteroid and thus is an excellent proxy to study early magmatism occurring on planets and moons. In this study, we focus on eucrite Pecora Escarpment (PCA) 82502, a medium-to fine-grained eucrite which chemical analyses suggest belongs to the main howardite-eucrite-diogenite clan, albeit with some peculiarities. We carried out backscattered electron and electron backscattered diffraction microscopy analyses of the meteorite along with step-heating 40 Ar/ 39 Ar dating analyses of various types of groundmass aliquots. We show that Pecora Escarpment 82502 is composed of medium-grained igneous crystalline clasts and smaller fractured satellite clasts surrounded by approximately 50 µm wide impact melt veins of the same composition. Our results show that the large crystalline clasts and fine-grained veins both display little evidence of shock processes. Six groundmass aliquots from large crystalline clasts returned concordant plateau (>70% of 39 Ar) or mini-plateau (50-70% of 39 Ar) 40 Ar/ 39 Ar ages with a weighted mean of 4531 AE 6 Ma (P = 0.67). Thermodynamic cooling and 40 Ar diffusion models suggest that the K/Ar system recorded and preserved the igneous age despite subsequent infiltration of hot and quickly quenched melt veins. Our new igneous age, combined with evidence for four other young volcanic and plutonic eucrites of similar age, shows that Vesta was still magmatically active around 4531 Ma. The lack of younger ages suggests that this age might well represent the end of the magmatic activity in the upper crust of Vesta. When combined with existing paleomagnetic constraints, our data suggest that 4 Vesta had an active dynamo that was still active~35 Ma after accretion. 620F. Jourdan et al.

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Origin, Internal Structure and Evolution of 4 Vesta

Cited by 3 publications

References 91 publications

The geological nature of dark material on Vesta and implications for the subsurface structure

The geological nature of dark material on Vesta and implications for the subsurface structure

Wetting property of Fe‐S melt in solid core: Implication for the core crystallization process in planetesimals

End of magmatism in the upper crust of asteroid 4 Vesta

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