Birth of the Kaapvaal Tectosphere 3.08 Billion Years Ago

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Science  19 Jan 2001:
Vol. 291, Issue 5503, pp. 465-468
DOI: 10.1126/science.291.5503.465

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The crustal remnants of Earth's Archean continents have been shielded from mantle convection by thick roots of ancient mantle lithosphere. The precise time of crust-root coupling (tectosphere birth) is poorly known but is needed to test competing theories of continental plate genesis. Our mapping and geochronology of an impact-generated section through the Mesoarchean crust of the Kaapvaal craton indicates tectosphere birth at 3.08 ± 0.01 billion years ago, roughly 0.12 billion years after crust assembly. Growth of the southern African mantle root by subduction processes occurred within about 0.2 billion years. The assembly of crust before mantle may be common to the tectosphere.

  • * To whom correspondence should be addressed. E-mail: demoser{at}

  • Present address: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Boston, MA 02139, USA.

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