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The mass of continental crust has not changed significantly since the early Archean

The mass of continental crust has not changed significantly since the early Archean. The mass of continental crust has not changed significantly since the early Archean. Proto-Archean. Formation of continental crust. Differenciation of primitive mantle. Enriched continental crust.

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The mass of continental crust has not changed significantly since the early Archean

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  1. The mass of continental crust has not changed significantly since the early Archean

  2. The mass of continental crust has not changed significantly since the early Archean

  3. Proto-Archean Formation of continental crust Differenciation of primitive mantle Enriched continental crust Undifferenciated primitive mantle Depleted mantle Formation of the bulk of the continental crust in the Proto-Archean Proto-Archean depleted mantle

  4. Geochemical evidence Nb/U Both incompatible elements U more incompatible than Nb Differenciation  higher Nb/U in continental crust lower Nb/U in depleted mantle Primitive mantle Nb/U ~30 Continental crust Nb/U ~10 Modern MORB Nb/U ~47 Archean basalts Nb/U ~ 30 - 47

  5. Late Archean basalts Lunnon Formation Yilgarn Craton Crustal contamination curve  Depleted mantle source  Amount of continental crust extracted is the same as today Sylvester et al. (1997)

  6. 3.5 Ga basalts and komatiites Barberton Montain Land, South Africa Average Nb/U : 43 Suggest an early depleted mantle and and amount of continental crust extracted similar as today Campbell (2003)

  7. 3.5 Ga Basalts from Pilbara Craton Sylvester ()

  8. ? Isotopic evidence Porpoise Cove 3.8 Ga Isua 3.8 Ga Depleted mantle at 3.8 Ga

  9. Recycling McCulloch and Bennett (1994)

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