The origin of the moon and the early history of the earth - a chemical model. Part 2: The earth

Journal Article · Mon Apr 01 00:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(91)90169-6· OSTI ID:5597978

O'Neill, H St.C. ^[1]

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1. Univ. Bayreuth (Germany)

The geochemical implications for the earth of a giant impact model for the origin of the earth-moon system are discussed, using a mass balance between three components: the proto-earth, the Impactor, and a late veneer. It is argued that the proto-earth accretes from material resembling a high temperature condensate from the solar nebula. Core formation takes place under very reducing conditions, resulting in the mantle of the proto-earth being completely stripped of all elements more siderophile than Fe, and partly depleted in the barely siderophile elements V, Cr, and perhaps Si. The Impactor then collides with the proto-earth, causing vaporisation of both the Impactor and a substantial portion of the earth's mantle. Most of this material recondenses to the earth, but some forms the moon. The Impactor adds most of the complement of the siderophile elements of the present mantle in an oxidized form. The oxidation state of the mantle is set near to its present, oxidized level. Finally, the addition of a late veneer, of composition similar to that of the H-group ordinary chondrites, accounts for the complement of the highly siderophile elements of the present mantle. The model accounts at least semi-quantitatively for the siderophile element abundances of the present mantle. Implications for the composition of the earth's core are discussed; the model predicts that neither S, O, nor Si should be present in sufficient quantities to provide the required light element in the core, whose identity, therefore, remains enigmatic.

• OSTI ID: 5597978
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 55:4; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EARTH MANTLE
GEOCHEMISTRY
EARTH PLANET
COSMOLOGICAL MODELS
PLANETARY EVOLUTION
LUNAR MATERIALS
MOON
CHEMICAL COMPOSITION
CHONDRITES
CHROMIUM
COMPARATIVE EVALUATIONS
ELEMENT ABUNDANCE
GEOLOGIC HISTORY
IRON
MASS BALANCE
ORIGIN
OXIDATION
SILICA
SOLAR NEBULA
VANADIUM
ABUNDANCE
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
ELEMENTS
MATERIALS
MATHEMATICAL MODELS
METALS
METEORITES
MINERALS
NEBULAE
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLANETS
SATELLITES
SILICON COMPOUNDS
SILICON OXIDES
SOLAR SYSTEM EVOLUTION
STONE METEORITES
TRANSITION ELEMENTS
580000* - Geosciences
640107 - Astrophysics & Cosmology- Planetary Phenomena