Skip to Main Content
Book Chapter

Strange partners: formation and survival of continental crust and lithospheric mantle

By
Nicholas T. Arndt
Nicholas T. Arndt
1
LCGA, UMR 5025 CNRS, 1381 rue de la Piscine, 3840 Grenoble, France
Search for other works by this author on:
Éric Lewin
Éric Lewin
1
LCGA, UMR 5025 CNRS, 1381 rue de la Piscine, 3840 Grenoble, France
Search for other works by this author on:
Francis Albarède
Francis Albarède
2
ENS-Lyon, place d’Italie, Lyon, France
Search for other works by this author on:
Published:
January 01, 2002

Abstract

Continental lithosphere is a sandwich of two layers, each composed of materials that are rare in the upper parts of the Earth. Continental crust consists of low-temperature distillates produced during a succession of melting events; the underlying lithosphere is a remarkably pure concentrate of high-temperature, highly refractory minerals. Material with intermediate compositions, which should have been far more abundant, is missing. The two dominant components of Archaean lithospheric mantle, olivine with 92–94% forsterite and similarly magnesian orthopyroxene, form only a small proportion of the residue of large-scale mantle melting. Their accumulation to form the lithosphere requires efficient sorting, to separate them from the products of lower-degree melting. This sorting, which is driven by the buoyancy of these low-density phases and their high viscosity, takes place during: (1) plume ascent through the segregation of residues of high- and low-degree melting; (2) recycling of the residues through the mantle; (3) crystallization in the crust of a Hadean magma ocean. The higher-than-normal orthopyroxene content in the Kaapvaal and other cratons is due in part to density sorting and in part to exsolution of majorite, a residual phase during komatiite melting. Secular variation in lithosphere composition (a decrease in the proportion of magnesian olivine and orthopyroxene and an increase in clinopyroxene and spinel) reflects a progressive decline in high-degree melting, a consequence of falling mantle temperatures.

You do not currently have access to this article.

Figures & Tables

Contents

Geological Society, London, Special Publications

The Early Earth: Physical, Chemical and Biological Development

C. M. R. Fowler
C. M. R. Fowler
University of London, UK
Search for other works by this author on:
C. J. Ebinger
C. J. Ebinger
University of London, UK
Search for other works by this author on:
C. J. Hawkesworth
C. J. Hawkesworth
University of Bristol, UK
Search for other works by this author on:
Geological Society of London
Volume
199
ISBN electronic:
9781862394476
Publication date:
January 01, 2002

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal