Detailed crustal thickness variations beneath the Illinois Basin area: Implications for crustal evolution of the midcontinent

Xiaotao Yang, Gary L. Pavlis, Michael W. Hamburger, Stephen Marshak, Hersh Gilbert, John Rupp, Timothy H. Larson, Chen Chen, N. Seth Carpenter

Research output: Contribution to journalArticle

Abstract

We present high-resolution imaging results of crustal and upper mantle velocity discontinuities across the Illinois Basin area using both common conversion point stacking and plane wave migration methods applied to P wave receiver functions from the EarthScope Ozark, Illinois, Indiana, and Kentucky experiment. The images reveal unusually thick crust (up to 62 km) throughout the central and southeastern Illinois Basin area. A significant Moho gradient underlies the NW trending Ste. Genevieve Fault Zone, which delineates the boundary between the Illinois Basin and Ozark Dome. Relatively thinner crust (<45 km) underlies most of the Precambrian highlands surrounding the Illinois Basin and beneath the rift-related structures of the Reelfoot Rift and the Rough Creek Graben. We consider four hypotheses to explain the presence of thick crust under the central and southeastern Illinois Basin. Crustal thickening may have been produced (1) prior to its accretion to North America around 1.55 Ga and is an inherited characteristic of this crustal province; (2) by underthrusting or shortening during Proterozoic convergent margin tectonics around 1.55–1.35 Ga; (3) by Late Precambrian magmatic underplating at the base of older crust, associated with the creation of the Eastern Granite-Rhyolite Province around 1.3 Ga; and (4) through crustal “relamination” during an episode of Proterozoic flat-slab subduction beneath the Illinois Basin, possibly associated with the Grenville Orogeny.

Original languageEnglish (US)
Pages (from-to)6323-6345
Number of pages23
JournalJournal of Geophysical Research: Solid Earth
Volume122
Issue number8
DOIs
StatePublished - Aug 2017

Keywords

  • Illinois Basin
  • North American Midcontinent
  • crustal evolution
  • crustal thickness
  • magmatic underplating
  • seismic imaging

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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