|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
,1
,2
,3
1 Department of Earth Sciences, University of Arkansas at Little Rock, 2801 S. University Avenue, Little Rock, Arkansas 72204, USA
2 Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006, Laramie, Wyoming 82071, USA
3 Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012 NHB MRC 121, Washington, DC 20013, USA
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.
Key Words: Cenozoic • tectonic uplift • climate change • incision • Rocky Mountains • Colorado Plateau
This article has been cited by other articles:
|
|
 |
|
  S. J. Davis, H. T. Mix, B. A. Wiegand, A. R. Carroll, and C. P. Chamberlain Synorogenic evolution of large-scale drainage patterns: Isotope paleohydrology of sequential Laramide basins Am J Sci, September 1, 2009; 309(7): 549 - 602. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. A. Riihimaki, P. W. Reiners, and E. L. Heffern Climate control on Quaternary coal fires and landscape evolution, Powder River basin, Wyoming and Montana Geology, March 1, 2009; 37(3): 255 - 258. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Moucha, A. M. Forte, D. B. Rowley, J. X. Mitrovica, N. A. Simmons, and S. P. Grand Mantle convection and the recent evolution of the Colorado Plateau and the Rio Grande Rift valley Geology, June 1, 2008; 36(6): 439 - 442. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. C. Clyde, W. Hamzi, J. A. Finarelli, S. L. Wing, D. Schankler, and A. Chew Basin-wide magnetostratigraphic framework for the Bighorn Basin, Wyoming Geological Society of America Bulletin, July 1, 2007; 119(7-8): 848 - 859. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
