Book contents
- Chondrules
- Cambridge Planetary Science
- Chondrules
- Copyright page
- Contents
- Contributors
- 1 Introduction
- Part I Observations of Chondrules
- 2 Multiple Mechanisms of Transient Heating Events in the Protoplanetary Disk
- 3 Thermal Histories of Chondrules
- 4 Composition of Chondrules and Matrix and Their Complementary Relationship in Chondrites
- 5 The Chondritic Assemblage
- 6 Vapor–Melt Exchange
- 7 Chondrules in Enstatite Chondrites
- 8 Oxygen Isotope Characteristics of Chondrules from Recent Studies by Secondary Ion Mass Spectrometry
- 9 26Al–26Mg Systematics of Chondrules
- 10 Tungsten Isotopes and the Origin of Chondrules and Chondrites
- 11 The Absolute Pb–Pb Isotope Ages of Chondrules
- 12 Records of Magnetic Fields in the Chondrule Formation Environment
- Part II Possible Chondrule-Forming Mechanisms
- Index
- Plate Section (PDF Only)
- References
7 - Chondrules in Enstatite Chondrites
from Part I - Observations of Chondrules
Published online by Cambridge University Press: 30 June 2018
- Chondrules
- Cambridge Planetary Science
- Chondrules
- Copyright page
- Contents
- Contributors
- 1 Introduction
- Part I Observations of Chondrules
- 2 Multiple Mechanisms of Transient Heating Events in the Protoplanetary Disk
- 3 Thermal Histories of Chondrules
- 4 Composition of Chondrules and Matrix and Their Complementary Relationship in Chondrites
- 5 The Chondritic Assemblage
- 6 Vapor–Melt Exchange
- 7 Chondrules in Enstatite Chondrites
- 8 Oxygen Isotope Characteristics of Chondrules from Recent Studies by Secondary Ion Mass Spectrometry
- 9 26Al–26Mg Systematics of Chondrules
- 10 Tungsten Isotopes and the Origin of Chondrules and Chondrites
- 11 The Absolute Pb–Pb Isotope Ages of Chondrules
- 12 Records of Magnetic Fields in the Chondrule Formation Environment
- Part II Possible Chondrule-Forming Mechanisms
- Index
- Plate Section (PDF Only)
- References
Summary
We review silicate chondrules and metal-sulfide nodules in unequilibrated enstatite chondrites (EH3 and EL3). Their unique mineral assemblages, with a wide diversity of opaque phases, nitrides, and nearly FeO-free enstatite, testify to exceptionally reduced conditions. While those have long been ascribed to a condensation sequence at supersolar C/O ratios, with the oldhamite-rich nodules among the earliest condensates, evidence for relatively oxidized local precursors suggests that their peculiarities may have been acquired during the chondrule-forming process itself. Silicate phases may have been then sulfidized in an O-poor and S-rich environment; whereas metal-sulfide nodules in EH3 chondrites could have originated in the silicate chondrules, those in EL3 may be impact products. The astrophysical setting (nebular or planetary) where such conditions were achieved, whether by depletion in water or enrichment in dry organics-silicate mixtures, is uncertain, but was most likely sited inside the snow line, consistent with the Earth-like oxygen isotopic signature of most EC silicates, with little data constraining its epoch yet.
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- ChondrulesRecords of Protoplanetary Disk Processes, pp. 175 - 195Publisher: Cambridge University PressPrint publication year: 2018
References
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