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The Hadean Crust: Evidence from >4 Ga Zircons

The Hadean Crust: Evidence from >4 Ga Zircons A review of continental growth models leaves open the possibilities that Earth during the Hadean Eon (∼4.5–4.0 Ga) was characterized by massive early crust or essentially none at all. Without support from the rock record, our understanding of pre-Archean continental crust must largely come from investigating Hadean detrital zircons. We know that these ancient zircons yield relatively low crystallization temperatures and some are enriched in heavy oxygen, contain inclusions similar to modern crustal processes, and show evidence of silicate differentiation at ∼4.5 Ga. These observations are interpreted to reflect an early terrestrial hydrosphere, early felsic crust in which granitoids were produced and later weathered under high water activity conditions, and even the possible existence of plate boundary interactions—in strong contrast to the traditional view of an uninhabitable, hellish world. Possible scenarios are explored with a view to reconciling this growing but fragmentary record with our knowledge of conditions then extant in the inner solar system. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Annual Review of Earth and Planetary Sciences Annual Reviews

The Hadean Crust: Evidence from >4 Ga Zircons

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References (168)

Publisher
Annual Reviews
Copyright
Copyright © 2009 by Annual Reviews. All rights reserved
ISSN
0084-6597
eISSN
1545-4495
DOI
10.1146/annurev.earth.031208.100151
Publisher site
See Article on Publisher Site

Abstract

A review of continental growth models leaves open the possibilities that Earth during the Hadean Eon (∼4.5–4.0 Ga) was characterized by massive early crust or essentially none at all. Without support from the rock record, our understanding of pre-Archean continental crust must largely come from investigating Hadean detrital zircons. We know that these ancient zircons yield relatively low crystallization temperatures and some are enriched in heavy oxygen, contain inclusions similar to modern crustal processes, and show evidence of silicate differentiation at ∼4.5 Ga. These observations are interpreted to reflect an early terrestrial hydrosphere, early felsic crust in which granitoids were produced and later weathered under high water activity conditions, and even the possible existence of plate boundary interactions—in strong contrast to the traditional view of an uninhabitable, hellish world. Possible scenarios are explored with a view to reconciling this growing but fragmentary record with our knowledge of conditions then extant in the inner solar system.

Journal

Annual Review of Earth and Planetary SciencesAnnual Reviews

Published: May 30, 2009

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