Title

Archean Asteroid Impacts on Earth: Stratigraphic and Isotopic Age Correlations and Environmental Consequences

Abstract

It is generally agreed that the Archean Earth was subject to a higher impact flux then on the present day Earth, however the rate and influence of large impacts on early Earth environments is still poorly understand. Here we present an overview of the evidence from the rock record for early impacts using the best-studied sequences containing impact layers in the Kaapvaal and Pilbara cratons, ranging in age from 3.47 to 2.49 Ga. A summary of correlations of individual spherule deposits is presented from within and between the two cratons using stratigraphy, petrography, zircon geochronology, platinum-group element (PGE) and Cr isotope geochemistry, and shocked mineralogy. We then evaluate the results of several studies that have suggested environmental and tectonic consequences of the impacts as predicted by impact modeling and discuss outstanding questions.

Publisher

Elsevier

Editor

Martin Van Kranendonk, Vickie Bennett, Elis Hoffmann

Publication Date

9-27-2018

Publication Title

Earth's Oldest Rocks

Department

Geology

Document Type

Book Chapter

DOI

10.1016/B978-0-444-63901-1.00008-3

Notes

Chapter 8.

Keywords

Archean bombardment, Impacts, Shocked minerals, Spherules

ISBN

9780444639011

Language

English

Format

text

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