The relation of mantle heterogeneity to the bulk composition and origin of the earth
Abstract
The heterogeneity of the mantle can be viewed in the context of models for accretion of the terrestrial planets from the solar nebula. Oxygen isotope ratios and mineralogy indicate the existence of hot planetesimals of diverse compositions. Assuming that nebular condensates range from a reduced state near the sun to an oxidized state near Jupiter, a new model is proposed for heterogeneous accretion of the earth beginning with hot, reduced condensates and ending with cool, oxidized condensates. The Ganapathy-Anders cosmochemical model for the bulk composition of the earth was tested by summing measured compositions for the three outer zones and likely compositions for the inner zones. Revisions are suggested, including reduction of the content of the early condensate from that suggested by taking the U concentration as 30 ng/g, as suggested by the naive interpretation of the heat flow.
- Publication:
-
Philosophical Transactions of the Royal Society of London Series A
- Pub Date:
- July 1980
- DOI:
- 10.1098/rsta.1980.0207
- Bibcode:
- 1980RSPTA.297..139S
- Keywords:
-
- Chemical Composition;
- Earth Mantle;
- Geochemistry;
- Planetary Evolution;
- Terrestrial Planets;
- Abundance;
- Astronomical Models;
- Deposition;
- Earth Core;
- Earth Crust;
- Heterogeneity;
- Particle Size Distribution;
- Lunar and Planetary Exploration;
- CHEMICAL COMPOSITION;
- EARTH MANTLE;
- GEOCHEMISTRY;
- PLANETARY EVOLUTION;
- TERRESTRIAL PLANETS;
- ABUNDANCE;
- ASTRONOMICAL MODELS;
- DEPOSITION;
- EARTH CORE;
- EARTH CRUST;
- HETEROGENEITY;
- PARTICLE SIZE DISTRIBUTION