Detrital zircon provenance of the Mesoproterozoic Midcontinent Rift, Lake Superior region, U.S.A

John P. Craddock, Alex Konstantinou, Jeffrey D. Vervoort, Karl R. Wirth, Cam Davidson, Lee Finley-Blasi, Natalie A. Juda, Erin Walker

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


We report the ages of detrital zircons (207Pb/206Pb LA-ICPMS; n p 1188) 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 (n p 99 zircons), Mt. Simon (n p 116), and Munising (n p 110) 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; n p 19) and is therefore not a rafted inclusion of Archean basement as previously suspected.

Original languageEnglish
Pages (from-to)57-73
Number of pages17
JournalJournal of Geology
Issue number1
Publication statusPublished - Jan 2013


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