Detrital zircon U-Pb geochronology of the Precambrian Middle Run Formation (Eastern North America Basement): Implications for Grenvillian foreland basin evolution and Midcontinent Rifting

J. M. Clay, D. P. Moecher, J. R. Bowersox

Research output: Contribution to journalArticlepeer-review

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Abstract

The Grenvillian orogeny and formation of the Midcontinent Rift system (MRS) are the primary tectonic events that modified Mesoproterozoic basement of eastern Laurentia prior to Neoproterozoic breakup of Rodinia. Trends of the Grenville Front Tectonic Zone (GFTZ), the cratonward limit of Grenvillian crustal reworking, and the East Continent Rift, an extension of the MRS, appear to converge in the subsurface of central Kentucky and southwestern Ohio. The Middle Run Formation (MRF) is a terrestrial clastic sequence that accumulated in the region of convergence and was interpreted as either a foreland basin or rift-fill deposit. Detrital zircon U-Pb geochronology for MRF feldspathic litharenites from three locations with varying proximity to the GFTZ provides the following constraints on the origin of the MRF and potential GFTZ-MRS interaction. (1) Youngest detrital zircon ages of 1.00 to 1.04 Ga limit the maximum depositional age of the Middle Run Formation to ~1.0 Ga, requiring the MRF to be a latest Grenvillian foreland deposit and not a syn-rift deposit. (2) The abundance of Midcontinent Rift System-age detrital zircon grains attests to the presence of rift-related felsic volcanism in the East Continent Rift and/or recycling of rift-fill sediments from the East Continent Rift into the MRF basin. (3) Detrital zircon age distributions reflect an actively unroofing Grenville orogen as represented by crustal components corresponding to Shawinigan (Geon 11), Elzevirian (Geon 12), and pre-Elzevirian (Geon 13) phases of the Grenville Orogenic Cycle, with significant Eastern Granite-Rhyolite Province basement (Geon 14) input. (4) The presence of only a minor Ottawan (Geon 10) detrital age component indicates that deeper Ottawan crust in the Grenville orogen had not been significantly exhumed. (5) Age modes in four of five samples correlated with the East Continent Rift magmatic interval (1117–1110 Ma) are only slightly older than the early phase of felsic Midcontinent Rift System magmatism (1109–1106 Ma) indicating that magmatism in the East Continent Rift was contemporaneous with the early phase of magmatism in the MRS. The MRF is confirmed to constitute the most proximal region of a Grenvillian clastic wedge that is only preserved or exposed in more distal regions of Laurentia.

Original languageEnglish
Article number106332
JournalPrecambrian Research
Volume364
DOIs
StatePublished - Sep 15 2021

Bibliographical note

Funding Information:
Supported by NSF EAR 1551342 and 1624663 and by the Ferm Fund of the UK Department of Earth and Environmental Sciences. We appreciate the guidance and support of the staff of the Arizona Laserchron Center. Samples were provided by the Kentucky Geological Survey and the Ohio Department of Natural Resources, Division of Geological Survey. We appreciate the counsel and support from Dave Harris and John Hickman of the Kentucky Geological Survey, and the staff at the Earth Analysis Research Library. Journal reviews by Rob Rainbird and Chris Spencer significantly improved the organization and clarity of the manuscript.

Funding Information:
Supported by NSF EAR 1551342 and 1624663 and by the Ferm Fund of the UK Department of Earth and Environmental Sciences . We appreciate the guidance and support of the staff of the Arizona Laserchron Center. Samples were provided by the Kentucky Geological Survey and the Ohio Department of Natural Resources, Division of Geological Survey. We appreciate the counsel and support from Dave Harris and John Hickman of the Kentucky Geological Survey, and the staff at the Earth Analysis Research Library. Journal reviews by Rob Rainbird and Chris Spencer significantly improved the organization and clarity of the manuscript.

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

  • Detrital zircon U-Pb geochronology
  • Grenville foreland basin
  • Midcontinent Rift System
  • Middle Run Formation
  • Provenance

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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