DOI: 10.1016/j.epsl.2017.11.027
Scopus记录号: 2-s2.0-85035032382
论文题名: Closed system oxygen isotope redistribution in igneous CAIs upon spinel dissolution
作者: Aléon J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 482 起始页码: 324
结束页码: 333
语种: 英语
英文关键词: calcium–aluminum-rich inclusions
; early solar system
; meteorites
; O isotopes
Scopus关键词: Aluminum
; Calcium
; Cooling systems
; Dissolution
; Meteorites
; Silicate minerals
; Silicates
; Titanium compounds
; Titanium dioxide
; Cooling history
; Early solar systems
; Isotope exchange
; Isotopic composition
; Mass fractionations
; Mass-balance calculations
; Protoplanetary disks
; Temperature range
; Isotopes
; aluminum
; calcium
; chondrite
; dissolution
; igneous rock
; inclusion
; oxygen isotope
; solar system
; spinel
英文摘要: In several Calcium–Aluminum-rich Inclusions (CAIs) from the CV3 chondrites Allende and Efremovka, representative of the most common igneous CAI types (type A, type B and Fractionated with Unknown Nuclear isotopic anomalies, FUN), the relationship between 16O-excesses and TiO2 content in pyroxene indicates that the latter commonly begins to crystallize with a near-terrestrial 16O-poor composition and becomes 16O-enriched during crystallization, reaching a near-solar composition. Mass balance calculations were performed to investigate the contribution of spinel to this 16O-enrichment. It is found that a back-reaction of early-crystallized 16O-rich spinel with a silicate partial melt having undergone a 16O-depletion is consistent with the O isotopic evolution of CAI minerals during magmatic crystallization. Dissolution of spinel explains the O isotopic composition (16O-excess and extent of mass fractionation) of pyroxene as well as that of primary anorthite/dmisteinbergite and possibly that of the last melilite crystallizing immediately before pyroxene. It requires that igneous CAIs behaved as closed-systems relative to oxygen from nebular gas during a significant fraction of their cooling history, contrary to the common assumption that CAI partial melts constantly equilibrated with gas. The mineralogical control on O isotopes in igneous CAIs is thus simply explained by a single 16O-depletion during magmatic crystallization. This 16O-depletion occurred in an early stage of the thermal history, after the crystallization of spinel, i.e. in the temperature range for melilite crystallization/partial melting and did not require multiple, complex or late isotope exchange. More experimental work is however required to deduce the protoplanetary disk conditions associated with this 16O-depletion. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110120
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR 7590, Sorbonne Universités, Museum National d'Histoire Naturelle, CNRS, UPMC, IRD, 61 rue Buffon, Paris, 75005, France
Recommended Citation:
Aléon J.. Closed system oxygen isotope redistribution in igneous CAIs upon spinel dissolution[J]. Earth and Planetary Science Letters,2018-01-01,482