Skip to Main Content
Book Chapter

Large-scale impacts and the evolution of the Earth's crust: The early years

By
Richard A.F. Grieve
Richard A.F. Grieve
Earth Sciences Sector, Natural Resources Canada, Ottawa, Ontario K1A 0E4, Canada
Search for other works by this author on:
Mark J. Cintala
Mark J. Cintala
NASA Johnson Space Center, Houston, Texas 77055, USA
Search for other works by this author on:
Ann M. Therriault
Ann M. Therriault
Earth Sciences Sector, Natural Resources Canada, Ottawa, Ontario K1A 0E4, Canada
Search for other works by this author on:
Published:
January 01, 2006

Modeling the effects of differential scaling of impact melt and transient cavity volumes indicates that impact melt volumes exceed transient cavity volumes at transient cavity diameters greater than ∼500 km on the Earth. This condition is not realized on the Moon until transient cavity diameters are greater than ∼3000 km. A reasoned case is made that because of this “differential scaling,” the large impact “basins” comparable in size to such lunar basins as Orientale, which must have been formed on the Hadean Earth, did not have an Orientale-like form. While their exact form is unknown, they were likely shallow structures, and they would have been characterized by voluminous central impact pools. These melt pools with their closed-system environment would likely differentiate, leading to the crystallization of more felsic rocks. This reprocessing of the Hadean crust by large-scale impacts provides a mechanism to produce pre–3.9 Ga zircons, without calling for plate-tectonic–related or other mechanisms of crustal recycling to produce felsic rocks. While the impact melting at a single one of such Hadean impact “basins” would be impressive, the cumulative effects would be potentially staggering, particularly if impact velocities during Hadean time were, as believed, lower than current velocities. Based on the number of large multi-ring basins on the Moon scaled to terrestrial conditions, cumulative melt production on the Hadean Earth by such basins alone would reach ∼1011−1012 km3. With the assumption that the impact melt pools were basaltic in composition, modeling with the crystalmelt fractionation software MELTS suggests the cumulative volume of felsic rocks potentially produced through the evolution of such impact melt pools could be significant.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

Processes on the Early Earth

Wolf Uwe Reimold
Wolf Uwe Reimold
Search for other works by this author on:
Roger L. Gibson
Roger L. Gibson
Search for other works by this author on:
Geological Society of America
Volume
405
ISBN print:
9780813724058
Publication date:
January 01, 2006

References

Related

Citing Books via

A comprehensive resource of eBooks for researchers in the Earth Sciences

Related Articles
Related Book Content
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal