Creation of a continent recorded in zircon zoning
Geology
By: D.E. Moser, J. R. Bowman, J. Wooden, J.W. Valley, F. Mazdab, and N. Kita
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Abstract
We have discovered a robust microcrystalline record of the early genesis of North American lithosphere preserved in the U-Pb age and oxygen isotope zoning of zircons from a lower crustal paragneiss in the Neoarchean Superior province. Detrital igneous zircon cores with ??18O values of 5.1???-7.1??? record creation of primitive to increasingly evolved crust from 2.85 ?? 0.02 Ga to 2.67 ?? 0.02 Ga. Sharp chemical unconformity between cores and higher ??18O (8.4???-10.4???) metamorphic overgrowths as old as 2.66 ?? 0.01 Ga dictates a rapid sequence of arc unroofing, burial of detrital zircons in hydrosphere-altered sediment, and transport to lower crust late in upper plate assembly. The period to 2.58 ?? 0.01 Ga included ???80 m.y. of high-temperature (???700-650 ??C), nearly continuous overgrowth events reflecting stages in maturation of the subjacent mantle root. Huronian continental rifting is recorded by the youngest zircon tip growth at 2512 ?? 8 Ma (??? 600 ??C) signaling magma intraplating and the onset of rigid plate behavior. This >150 m.y. microscopic isotope record in single crystals demonstrates the sluggish volume diffusion of U, Pb, and O in zircon throughout protracted regional metamorphism, and the consequent advances now possible in reconstructing planetary dynamics with zircon zoning. ?? 2008 The Geological Society of America.
Suggested Citation
Moser, D., Bowman, J.R., Wooden, J., Valley, J., Mazdab, F., Kita, N., 2008, Creation of a continent recorded in zircon zoning: Geology, v. 36, no. 3, p. 239-242, https://doi.org/10.1130/G24416A.1.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Creation of a continent recorded in zircon zoning |
| Series title | Geology |
| DOI | 10.1130/G24416A.1 |
| Volume | 36 |
| Issue | 3 |
| Year Published | 2008 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geology |
| First page | 239 |
| Last page | 242 |