气候变化领域集成服务门户(CCPortal): A model for evolving crust on 4 Vesta through combined compositional and thermal modelling

CCPortal

DOI	10.1016/j.epsl.2021.117105
	A model for evolving crust on 4 Vesta through combined compositional and thermal modelling
	Mitchell J.T.; Tomkins A.G.; Newton C.; Johnson T.E.
发表日期	2021
ISSN	0012821X
卷号	571
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.
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
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203224
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
推荐引用方式 GB/T 7714	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],2021,571.
APA	Mitchell J.T.,Tomkins A.G.,Newton C.,&Johnson T.E..(2021).A model for evolving crust on 4 Vesta through combined compositional and thermal modelling.Earth and Planetary Science Letters,571.
MLA	Mitchell J.T.,et al."A model for evolving crust on 4 Vesta through combined compositional and thermal modelling".Earth and Planetary Science Letters 571(2021).