Detrital Zircon Provenance of the Mesoproterozoic Midcontinent Rift, Lake Superior Region, U.S.A
We report the ages of detrital zircons (207Pb/206Pb LA-ICPMS; ) from 12 clastic units that are representative of the Mesoproterozoic Midcontinent Rift System (MRS) of North America. Magmatism of the MRS spanned 1115–1085 Ma. The Puckwunge, Nopeming, and Bessemer basal sandstones and the Oronto and B...
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| Published in: | The Journal of geology Vol. 121; no. 1; p. 000 |
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| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Chicago
University of Chicago Press
01-01-2013
University of Chicago, acting through its Press |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | We report the ages of detrital zircons (207Pb/206Pb LA-ICPMS;
) from 12 clastic units that are representative of the Mesoproterozoic Midcontinent Rift System (MRS) of North America. Magmatism of the MRS spanned 1115–1085 Ma. The Puckwunge, Nopeming, and Bessemer basal sandstones and the Oronto and Bayfield Group sandstones received a predominance of Keweenaw Rift–Grenville (1.3–1.0 Ga) zircons but also contributions of Wolf River (1.45 Ga), Yavapai (1.75 Ga), Penokean (1.8 Ga), and Archean (2.6–3.6 Ga) ages. Interflow sedimentary rocks in the North Shore Volcanic Group received only rift-aged zircons. The maximum depositional ages derived from detrital zircons also better constrain the age-stratigraphic relationship of the unfossiliferous rift section, in comparison to the overlying fossiliferous Franconia (
zircons), Mt. Simon (
), and Munising (
) late Cambrian transgressive sands. We also report the date of a granite xenolith (∼1 km3) in the Beaver Bay Complex, which has a rift age (1091 Ma;
) and is therefore not a rafted inclusion of Archean basement as previously suspected. |
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| ISSN: | 0022-1376 1537-5269 |
| DOI: | 10.1086/668635 |