Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Iizuka, T. Articles by Maruyama, S. Search for Related Content GeoRef GeoRef Citation

U-Pb and Lu-Hf isotope systematics of zircons from the Mississippi River sand: Implications for reworking and growth of continental crust

¹ Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ookayama Meguro-ku, Tokyo 152-8551, Japan
² Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA
³ Department of Igneous Petrology, Rio de Janeiro State University, Rua Sao Francisco Xavier 524, Sala A-4023, Maracana, Rio de Janeiro, Brazil
⁴ Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ookayama Meguro-ku, Tokyo 152-8551, Japan

We carried out in situ U-Pb and Lu-Hf isotope analyses of detrital zircons from the Mississippi River in order to understand crustal reworking and continental growth rates. The U-Pb analyses for 416 zircons reveal three major peaks of crust formation at 2.8–2.6 Ga, 1.8–0.9 Ga, and after 0.2 Ga. Initial Hf isotope ratios were obtained for 402 of the dated zircons, and only 8% of the zircons have _Hf(T)DM values less negative than –2.5. These data correspond to a crustal residence time of <120 m.y. This finding indicates that crustal reworking was a very important process in continental crust formation. The _Hf(T)DM population demonstrates that reworking was predominant at 2.5–2.0 Ga and after 0.9 Ga, whereas juvenile crust formation dominated between 2.0 and 1.6 Ga. We calculated the mantle-extraction model ages to estimate the continental growth rate. Approximately half of the grains have model ages between 2.0 and 1.3 Ga, indicating rapid crustal growth during this time. The continental growth rate suggests that 15% and 78% crust in the source region of the zircons formed by 2.5 and 1.3 Ga, respectively.

Key Words: zircon • U-Pb • Lu-Hf • continental growth • crustal reworking • laser ablation–ICP-MS

This article has been cited by other articles:

				X. Liu, S. Gao, C. Diwu, and W. Ling Precambrian crustal growth of Yangtze Craton as revealed by detrital zircon studies Am J Sci, April 1, 2008; 308(4): 421 - 468. [Abstract] [Full Text] [PDF]

				A. Zeh, A. Gerdes, R. Klemd, and J. M. Barton Jr Archaean to Proterozoic Crustal Evolution in the Central Zone of the Limpopo Belt (South Africa-Botswana): Constraints from Combined U-Pb and Lu-Hf Isotope Analyses of Zircon J. Petrology, August 1, 2007; 48(8): 1605 - 1639. [Abstract] [Full Text] [PDF]

				P. A. Mueller, D. A. Foster, D. W. Mogk, J. L. Wooden, G. D. Kamenov, and J. J. Vogl Detrital mineral chronology of the Uinta Mountain Group: Implications for the Grenville flood in southwestern Laurentia Geology, May 1, 2007; 35(5): 431 - 434. [Abstract] [Full Text] [PDF]

				T. Iizuka, K. Horie, T. Komiya, S. Maruyama, T. Hirata, H. Hidaka, and B. F. Windley 4.2 Ga zircon xenocryst in an Acasta gneiss from northwestern Canada: Evidence for early continental crust Geology, April 1, 2006; 34(4): 245 - 248. [Abstract] [Full Text] [PDF]