DOI: 10.1016/j.epsl.2021.117105
论文题名: A model for evolving crust on 4 Vesta through combined compositional and thermal modelling
作者: Mitchell J.T. ; Tomkins A.G. ; Newton C. ; Johnson T.E.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 571 语种: 英语
中文关键词: diogenite
; eucrite
; melts
; thermal modelling
; THERMOCALC
; Vesta
英文关键词: Calcium
; Metal melting
; $+26$/Al
; Diogenite
; Eucrite
; Evolution modeling
; Melt
; Orthopyroxene
; Thermal evolution
; Thermal model
; Thermocalc
; Vesta
; Meteorites
; accretion
; aluminum
; asteroid
; calcium
; diogenite
; eucrite
; magma
; melting
; orthopyroxene
; petrology
; Asteroidea
英文摘要: Combined phase equilibrium and thermal modelling has been used to investigate the evolution of asteroid 4 Vesta. Orthopyroxene compositions of 200 natural diogenite meteorites are used as a basis for constructing a staged mantle melting model for Vesta, which is then used to develop a staged thermal evolution model. Our pMELTS models find that removal of 15–20% of a mean eucrite component from an initial Vestan mantle composition allows a second stage of melting that crystallises low-calcium orthopyroxenes that match the observed compositions of those in natural diogenites, whereas single stage melting produces orthopyroxenes that are too calcic. Using the compositions generated by the pMELTS modelling, THERMOCALC models were created for an initial Vestan mantle composition and an evolved composition generated by a melt extraction stage. These models suggest that melt production for second-stage diogenite generation required considerably hotter temperatures (>1340 °C) than for eucrites (<1240 °C). Staged and layered thermal evolution models developed using these composition and temperature constraints, based on the decay of 26Al and 60Fe, suggest that Vesta accreted 1.50 to 1.75 Myr after calcium-aluminium inclusion (CAI) formation. Earlier accretion results in conditions that are inconsistent with the petrology of the HED meteorites, whereas later accretion predicts temperatures that are insufficient to produce diogenites. We suggest that upward migration of 26Al-rich melt initially created a convecting shallow magma ocean of <20 km depth that rapidly crystallised to form a 26Al-rich eucritic crust that acted as a hot insulating lid. The second stage of crust formation began once the depleted mantle residue reached high enough temperatures to produce diogenite-forming magmas. These results further support the view that diogenites likely formed as crustal intrusions rather than as magma ocean cumulates. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165602
Appears in Collections: 气候变化与战略
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作者单位: School of Earth, Atmosphere & Environment, Monash University, Melbourne, Australia; School of Physics & Astronomy, Monash University, Melbourne, Australia; School of Earth & Planetary Sciences, The Institute for Geoscience Research, Curtin University, Perth, Australia
Recommended Citation:
Mitchell J.T.,Tomkins A.G.,Newton C.,et al. A model for evolving crust on 4 Vesta through combined compositional and thermal modelling[J]. Earth and Planetary Science Letters,2021-01-01,571