Looking for:
Colorado plateauColorado plateau. Geology of the Colorado Plateau: Grand Canyon National Park
Rebecca M. Flowers; The enigmatic rise of the Colorado Plateau. Geology ;; 38 7 : — This problem is most dramatically manifest when standing on the rim of the Grand Canyon, viewing the extraordinary m-deep gorge carved into nearly horizontal sedimentary rocks that were deposited during the m. What caused the elevation gain of this previously stable cratonic region in Cenozoic time?
Did the source of buoyancy for plateau uplift arise from the crust, lithospheric mantle, or asthenosphere, or through some combination of the three?
Why did this low-relief plateau escape significant upper crustal strain during uplift, in contrast to the Cenozoic surface deformation that is so strikingly apparent in the high-relief landscape of the surrounding Rocky Mountain, Rio Grande Rift, and Basin and Range provinces Fig.
The answers to these contentious questions are significant for understanding how deep-seated processes control the elevation change and topographic evolution of Earth's surface. These relationships are particularly cryptic within continental interior settings like the Colorado Plateau.
Although there is a first-order understanding of vertical motions in areas close to plate boundaries, there is comparatively little consensus on the causes of such motions distal from these margins.
The Colorado Plateau exemplifies this problem. The protracted history of Cordilleran orogenesis affords numerous opportunities for how and when uplift of the Colorado Plateau might have occurred. The region is last known to have been at sea level in Late Cretaceous time, based on the widespread occurrence of marine sediments of this age. Elevation gain could have occurred in Early Tertiary time associated with Sevier-Laramide contraction, mid-Tertiary time synchronous with the proposed demise of the Laramide flat slab, or Late Tertiary time coeval with regional extensional tectonism in adjacent provinces.
Hypothesized mechanisms include partial removal of the lithospheric mantle e. It is clear that there is no shortage of mechanisms that could explain the plateau's origin. The core challenge is determining which mechanism, or combination of mechanisms, is indeed the cause. Crucial for solving this problem are constraints on the plateau's elevation history, erosional evolution, magmatism patterns, and modern lithospheric structure. Liu and Gurnis , p. Liu and Gurnis focus on an explanation for the Late Cretaceous through mid-Cenozoic uplift history of the southwestern plateau, whereas van Wijk et al.
In the first study, Liu and Gurnis employ an inverse mantle convection model to compute the changing dynamic topography, the vertical motion of Earth's surface in response to mantle flow. This model of dynamic uplift linked to Farallon slab evolution predicts an initial phase of subsidence associated with flat slab development, followed by two phases of uplift in Late Cretaceous and Eocene times due to progressive slab removal.
Liu and Gurnis invoke mantle upwellings to induce the remainder of the plateau's uplift in the Oligocene. A distinctive result of the model is the prediction that the plateau was tilted to the northeast in Late Cretaceous—Early Tertiary time, with later differential elevation gain of the plateau interior that diminished or reversed this tilt.
The authors note that their results compare favorably with the conclusions of two recent investigations on the southwestern plateau Flowers et al. In the second study, van Wijk et al. The lithospheric thickness contrast is observed seismically and attributed to Cenozoic extension of the adjoining regions.
This work finds that asthenospheric upwelling and lithospheric mantle removal along the plateau edges can account for Neogene—Quaternary patterns of magmatism, distinctive shallow mantle seismic anomalies, and several hundred meters of differential uplift along the plateau margins. One question arising from these two studies is: are their conclusions compatible? Van Wijk et al. Their results do not exclude earlier uplift.
Thus, to first order, the results of these two studies do not appear to be mutually exclusive. When integrated, they would predict a complex spatio-temporal progression of uplift migrating from southwest to northeast in Late Cretaceous through mid-Cenozoic time, with a late Cenozoic uplift phase and development of differential topography along the plateau edges.
The other obvious question that emerges from these efforts is both more important and far more difficult to answer. Do the proposed models accurately describe the true origin and evolution of Colorado Plateau elevation? Both studies are significant in advancing potentially important and viable mechanisms to explain key features of the plateau. They are therefore serious contenders among the suite of competing models for plateau elevation gain.
However, determining the extent to which these models approximate reality must in part await additional constraints on the uplift history with which to further test the predictions of each study. One reason why resolving the cause of plateau uplift is such a tough problem is that deciphering the paleoelevation of continents is extremely difficult, and the plateau's elevation history is critically important for isolating the correct uplift mechanism.
Dated marine deposits can determine when an area was at sea level, but no direct, reliable proxy yet exists for the past altitude of an elevated region. Strategies for addressing this problem commonly involve estimating paleotemperature, constraining paleorelief, deciphering paleohydrology, and reconstructing erosional and depositional histories.
Paleotemperature estimates for inferring paleoelevation are typically made by stable isotope and paleobotany studies. Application of the new clumped isotope thermometer on the Colorado Plateau Huntington et al. The past amount of relief in a landscape imposes a minimum constraint on paleoelevation, and resolving the carving of the Grand Canyon is an obvious target for constraining Colorado Plateau paleorelief.
Recent approaches to determine the history of canyon incision include U-Pb dating of carbonate cave deposits Polyak et al. The reorganization of plateau paleodrainage systems in part reflects the plateau's topographic development; deciphering this history has been the target of numerous stratigraphic, geochronologic, and isotopic studies e. Stratigraphic and thermochronologic efforts have been used to resolve the plateau's erosional and depositional evolution that is linked with its history of elevation change e.
A basalt vesicularity study differs from the investigations above in its attempt to directly constrain paleoatmospheric pressure, and therefore paleoelevation, from the size of vesicles in plateau lavas Sahagian et al. Not surprisingly, contradictory interpretations regarding the uplift history of the Colorado Plateau often arise from the diverse information yielded by the many studies in this region.
The two geodynamic studies in this issue of Geology underscore the probable complexity of the plateau's history. They especially highlight the unlikelihood of the entire plateau undergoing a single spatially uniform phase of surface uplift, and emphasize the potential for significant geographic and temporal heterogeneity in elevation gain.
Such a history would only exacerbate the challenge of accurately reconstructing the plateau's evolution from the geological record. Perhaps some of the geological data that seemingly conflict in the context of simpler uplift models can be reconciled when evaluated in the framework of the more complex patterns of elevation gain predicted by these geodynamic studies.
The inventive new approaches for deciphering the plateau's history coupled with testable predictions from geodynamic models are yielding fresh insights into the perplexing story behind the topographic rise of the Colorado Plateau.
Sign In or Create an Account. User Tools Dropdown. Sign In. Search Dropdown Menu. Advanced Search. Skip Nav Destination Article Navigation. Research Article July 01, The enigmatic rise of the Colorado Plateau Rebecca M. Flowers Rebecca M. Google Scholar. Geology 38 7 : — Article history first online:. Figure 1. View large Download slide. Topographic map of the Colorado Plateau and adjacent provinces.
Close Modal. This site uses cookies. By continuing to use our website, you are agreeing to our privacy policy.
Colorado Plateaus Province (U.S. National Park Service)
Originally named by John Wesley Powell, the Colorado Plateau comprises a series of tablelands plateaus colorado plateau mesas located within an immense basin surrounded by highlands. Stream valleys that are typically narrow and widely spaced dissect the colorado plateau, as do larger valleys, including the most spectacular — the Grand Canyon. Prehistorically, many of these valleys were the homes of prehistoric farmers. The environment colorado plateau the canyon bottoms was so different from the rest of the Plateau, however, that it is colorado plateau separately.
Temperature: At the lower elevations of the Plateau, temperatures range from the low 20s to the mids F. At higher elevations, summer temperatures rarely exceed 70 degrees, and winter temperatures in the single перейти are common.
Elevation: The mean elevation on the Plateau is 1, meters 6, feetbut the elevational range of Plateau includes canyon bottoms at less than meters 2, feet and mountain /56230.txt a staggering 3, meters 12, feet above sea level. Vegetation: At low elevations, the Plateau is covered with arid shrublands and grasses, with sagebrush as the dominant plant species. Higher elevations bear woodlands dominated by pinyon pine, juniper, and shrubs.
Higher still, montane forests plateai by ponderosa pine, Douglas fir, lodgepole pine, and aspen cover the land. Geology: Primarily sedimentary rocks formed tens to hundreds of millions of years ago. Sandstones, shales, and limestones are common, as are fantastic rock formations molded by wind and water. Volcanic rocks are also common in продолжить чтение areas of the Plateau with volcanic history, such as the Hopi Buttes, Sunset Crater and the San Francisco Peaks.
Part of a series of articles titled Collorado the Southwest. Previous: Environmental Definitions colorado plateau the Southwest. Next: Transition Highlands and the Mogollon Rim.
National Park Service Search Search. Exiting nps. Contact Us. The Colorado Plateau. Caldon Prehistorically, many of these valleys were the homes of prehistoric farmers. Area:sq. Precipitation: Averages 20 cm адрес in colorado plateau year. You Might Also Like. Loading results Tags arches national park aztec ruins national monument bandelier national monument canyon de chelly national monument canyonlands national park capitol reef national park chaco culture national /30132.txt park el malpais national monument el morro national monument glen canyon national recreation area grand colorado plateau national park hovenweep national monument hubbell trading post national historic site mesa verde national park natural bridges national monument нажмите для продолжения national monument petrified forest colorado plateau park petroglyph national monument rainbow bridge national monument colorado plateau pueblo missions national monument sunset crater volcano national platea walnut canyon colorado plateau monument wupatki national monument yucca house national monument swscience american southwest southwest definitions ancestral puebloan pinyon-juniper woodlands pllateau forests geology sinagua cohonina fremont.
Last updated: December 1,
Comments
Post a Comment