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Science 24 January 1997:
Vol. 275. no. 5299, pp. 521 - 523
DOI: 10.1126/science.275.5299.521
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Reports

Niobium/Uranium Evidence for Early Formation of the Continental Crust

Paul J. Sylvester, * Ian H. Campbell, Deborah A. Bowyer

Niobium/uranium ratios in greenstone-belt basalts and gabbros indicate that parts of the Late Archean mantle beneath Western Australia underwent a level of melt extraction, resulting in formation of the continental crust, comparable to that seen in the present mantle. The implication is either that (i) the amount of continental crust that formed before 2.7 × 109 years ago was much greater than generally thought or (ii) crustal growth occurred by severe depletion of small volumes of the mantle rather than by moderate depletion of a large volume of mantle.

Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia.
*   To whom correspondence should be addressed.

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Geochemical and petrological evidence for a suprasubduction zone origin of Neoarchean (ca. 2.5 Ga) peridotites, central orogenic belt, North China craton.
A. Polat, C. Herzberg, C. Munker, R. Rodgers, T. Kusky, J. Li, B. Fryer, and J. Delaney (2006)
Geological Society of America Bulletin 118, 771-784
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Secular variations of N-isotopes in terrestrial reservoirs and ore deposits.
R. Kerrich, Y. Jia, C. Manikyamba, and S.M. Naqvi (2006)
Geological Society of America Memoirs 198, 81-104
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Geochemistry of Neoarchean (ca. 2.55-2.50 Ga) volcanic and ophiolitic rocks in the Wutaishan greenstone belt, central orogenic belt, North China craton: Implications for geodynamic setting and continental growth.
A. Polat, T. Kusky, J. Li, B. Fryer, R. Kerrich, and K. Patrick (2005)
Geological Society of America Bulletin 117, 1387-1399
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Constraints on continental growth models from Nb/U ratios in the 3.5 Ga Barberton and other Archaean basalt-komatiite suites.
I. H. Campbell (2003)
Am J Sci 303, 319-351
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Late Palaeozoic Ultramafic Lavas in Yunnan, SW China, and their Geodynamic Significance.
N. FANG and Y. NIU (2003)
J. Petrology 44, 141-158
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The oldest rocks on Earth: time constraints and geological controversies.
B. S. Kamber, S. Moorbath, and M. J. Whitehouse (2001)
Geological Society, London, Special Publications 190, 177-203
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Evolution of the Continents and the Atmosphere Inferred from Th-U-Nb Systematics of the Depleted Mantle.
K. D. Collerson and B. S. Kamber (1999)
Science 283, 1519-1522
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