History and causes of post-Laramide relief in the Rocky Mountain orogenic plateau

Abstract

Research Article| March 01, 2006 History and causes of post-Laramide relief in the Rocky Mountain orogenic plateau Margaret E. McMillan; Margaret E. McMillan 1Department of Earth Sciences, University of Arkansas at Little Rock, 2801 S. University Avenue, Little Rock, Arkansas 72204, USA Search for other works by this author on: GSW Google Scholar Paul L. Heller; Paul L. Heller 2Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006, Laramie, Wyoming 82071, USA Search for other works by this author on: GSW Google Scholar Scott L. Wing Scott L. Wing 3Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012 NHB MRC 121, Washington, DC 20013, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Margaret E. McMillan 1Department of Earth Sciences, University of Arkansas at Little Rock, 2801 S. University Avenue, Little Rock, Arkansas 72204, USA Paul L. Heller 2Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006, Laramie, Wyoming 82071, USA Scott L. Wing 3Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012 NHB MRC 121, Washington, DC 20013, USA Publisher: Geological Society of America Received: 29 Oct 2004 Revision Received: 28 May 2005 Accepted: 31 Aug 2005 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2006) 118 (3-4): 393–405. https://doi.org/10.1130/B25712.1 Article history Received: 29 Oct 2004 Revision Received: 28 May 2005 Accepted: 31 Aug 2005 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Margaret E. McMillan, Paul L. Heller, Scott L. Wing; History and causes of post-Laramide relief in the Rocky Mountain orogenic plateau. GSA Bulletin 2006;; 118 (3-4): 393–405. doi: https://doi.org/10.1130/B25712.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Rocky Mountain orogenic plateau has the highest mean elevation and topographic relief in the contiguous United States. The mean altitude exceeds 2 km above sea level and relief increases from 30 m in the river valleys of the Great Plains to more than 1.6 km deep in the canyons and basins of the Rocky Mountains and Colorado Plateau. Despite over a century of study, the timing and causes of elevation gain and incision in the region are unclear. Post-Laramide development of relief is thought to either result from tectonic activity or climatic change. Interpretation of which of these causes dominated is based upon reconstruction of datums developed from, and supported by, paleoelevation proxies and interpretations of landscape incision. Here we reconstruct a datum surface against which regional incision can be measured in order to evaluate late Cenozoic tectonic and climatic influences. The distribution, magnitude, and timing of post-Laramide basin filling and subsequent erosion are constrained by depositional remnants, topographic markers, and other indicators across the region. We suggest that post-Laramide basin filling resulted from slow subsidence during Oligocene to Miocene time. Incision into this basin fill surface began in late Miocene time and continues today. The pattern of incision is consistent with control by localized extensional tectonism superimposed upon regional domal surface uplift. Localized extension is associated with the projection of the Rio Grande Rift into the central Rockies, and the domal uplift generally coincides with the position of buoyant mantle anomalies interpreted at depth. If the magnitudes of incision directly reflect magnitudes of surface elevation gain, they are less than can be resolved by existing paleoelevation proxy methods. In addition, the combination of post-Laramide subsidence followed by regional surface uplift reduces the net magnitude of surface elevation change since Laramide time. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.