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GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 158-9
Presentation Time: 10:20 AM

MULTIDISCIPLINARY APPROACH TO CHARACTERIZE TECTONIC HISTORY OF THE MIDCONTINENT USA CRATONIC PLATFORM: THE OZARK PLATEAU - ILLINOIS BASIN BOUNDARY


DELUCIA, Michael S.1, MARSHAK, Stephen2, GUENTHNER, William R.1, MURPHY, Benjamin S.3, EGBERT, Gary4, PAVLIS, Gary5, GILBERT, Hersh6, HAMBURGER, Michael W.7, CHEN, Chen8, YANG, Xiaotao9, LARSON, Timothy10 and RUPP, John A.11, (1)Department of Geology, University of Illinois at Urbana-Champaign, 3081 Natural History Building, 1301 W. Green St., Urbana, IL 61801, (2)Dept. of Geology, University of Illinois, Natural History Building, 1301 W. Green St., Urbana, IL 61801, (3)College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Building, Corvallis, OR 97331-5503, (4)College of Earth, Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin. Bldg, Corvallis, OR 97331-5503, (5)Earth and Atmospheric Sciences, Indiana University, Bloomington, IN 47405, (6)Dept. of Geoscience, University of Calgary, 2500 University Dr. NW, Calgary, BC T2N 1N4, Canada, (7)Dept. of Geological Sciences, Indiana University, Bloomington, IN 47405, (8)Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, (9)Department of Geosciences, University of Massachusetts Amherst, 627 N. Pleasant St., Amherst, MA 01003, (10)Illinois State Geological Survey, University of Illinois, Champaign, IL 61820, (11)School of Public and Environmental Affairs, Indiana University, Bloomington, IN 47405

The Midcontinent USA cratonic platform was modified by several tectonic events, producing basins and domes and fault-and-fold zones. Data from EarthScope arrays and other sources covering the Ozark Plateau (Missouri) and Illinois Basin exemplifies how a multidisciplinary study can provide insight into the history of this tectonism. The Ozark Plateau, underlain by the structural Ozark Dome (OD), rises 0.7 km above the adjacent Illinois Basin (IB). Structural relief across this boundary, as defined by a DEM of the Great Unconformity, locally exceeds 7 km. Since the same suite of 1.47 Ga felsic extrusive rocks underlie the Great Unconformity of both provinces, the top of crystalline basement lay at the Earth's surface then. Subsequent rifting established a rectilinear array of steep fault zones cutting across basement. EarthScope MT data reveals a distinct NW-trending zone of low electrical resistance (the Missouri High-Conductivity Belt) across Missouri, suggesting some zones focused fluid flow in the past. Notably, this belt correlates with the Missouri Gravity Low, with magnetic anomalies, and with local fault traces. Thermal history modeling of zircon (U-Th)/He dates constrains protracted reheating during the Mesoproterozoic, indicating sedimentary burial in excess of 6 km (perhaps by Grenville foreland deposits), followed by Neoproterozoic cooling (i.e. exhumation) to form the Great Unconformity prior to Rodinia breakup. The OD and IB developed due to differential vertical motion that began in the Cambrian. Seismic data (including OIINK results) suggests that differential subsidence may be influenced by Moho-depth variations. Structure-contour maps, surface-geology maps, and seismic-reflection profiles emphasize that fault-and-fold zones reactivated multiple times, and that epeirogenic movement was localized by faulting. The seismically active Ste. Genevieve fault represents the surface manifestation of the OD-IB boundary. Apatite thermochronology suggests that Mesozoic exhumation removed post-Pennsylvanian cover prior to Pangaea breakup. The association of exhumation with supercontinent breakup suggests a link between mantle phenomena and uplift. Post-Pangaea river incision of OD bedrock and ongoing seismicity along the plateau’s borders suggest that uplift slowly continues.

Session No. 158

T64. Beyond EarthScope in the Eastern U.S.—What We've Learned and What Needs Doing Next
Tuesday, 6 November 2018: 8:00 AM-12:00 PM
Room 238-239 (Indiana Convention Center)
Geological Society of America Abstracts with Programs. Vol. 50, No. 6
doi: 10.1130/abs/2018AM-322267
© Copyright 2018 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
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