Skip to main content
Advanced Search

Filters: Tags: paleoclimate (X)

36 results (274ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
thumbnail
During the Pliocene to middle Pleistocene, pluvial lakes in the western Great Basin repeatedly rose to levels much higher than those of the well-documented late Pleistocene pluvial lakes, and some presently isolated basins were connected. Sedimentologic, geomorphic, and chronologic evidence at sites shown on the map indicates that Lakes Lahontan and Columbus-Rennie were as much as 70 m higher in the early-middle Pleistocene than during their late Pleistocene high stands. Lake Lahontan at its 1400-m shoreline level would submerge present-day Reno, Carson City, and Battle Mountain, and would flood other now-dry basins. To the east, Lakes Jonathan (new name), Diamond, Newark, and Hubbs also reached high stands during...
During the last glacial maximum (LGM), the western Uinta Mountains of northeastern Utah were occupied by the Western Uinta Ice Field. Cosmogenic Be-10 surface-exposure ages from the terminal moraine in the North Fork Provo Valley and paired Al-26 and Be-10 ages from striated bedrock at Bald Mountain Pass set limits on the timing of the local LGM. Moraine boulder ages suggest that ice reached its maximum extent by 17.4 +/- 0.5 ka (+/- 2 sigma). Be-10 and Al-26 measurements on striated bedrock from Bald Mountain Pass, situated near the former center of the ice field, yield a mean Al-26/Be-10 ratio of 5.7 +/- 0.8 and a mean exposure age of 14.0 +/- 0.5 ka, which places a minimum-limiting age on when the ice field melted...
This study provides a detailed pedogenic evaluation of two Upper Triassic (Late Norian through Rhaetian) stratigraphic intervals in New Mexico in order to assess the climate and ecology of the Latest Triassic, which ended in a mass extinction. The two study areas are located in north?central and east-central New Mexico and are separated by 200 km. Each section contains abundant paleosols of varying maturity with features that reflect an arid to semiarid climate. There is little pedogenic variation throughout the strata at each location, and a typical paleosol profile is about 1 m thick and has an AB?Bw?Bk?BC horizon succession. Bkm, Bss, Bssk, or Bssg horizons are present in some paleosols. Micromorphological features...
thumbnail
The drilling project at Owens Lake commenced in April,1991. This Open-File Report represents an effort to makeavailable to other researchers our preliminary datacollected during the first year of study followingcompletion of the core-drilling phase. Nineteen datacollections and preliminary interpretations are presentedin the following sections. They are the work of fifteenfirst-authors and their numerous co-authors. Broadly,their topics include a field log of the core(1 contribution), sedimentological analyses (1), clay-mineral identification (1), geochemical analyses (5),dating and age estimates of the cored sediments (4), andidentifications of fossil materials (7).
thumbnail
Great thicknesses of eolian dune deposits of early Oligocene age crop out in the Chuska Mountains of northwestern New Mexico-Arizona (as much as 535 m thick) and in the Mogollon-Datil volcanic field of western New Mexico-Arizona (as much as 300 m thick). 40Ar/39Ar ages of intercalated volcanic rocks indicate eolian deposition in these areas was approximately synchronous, with eolian accumulation beginning regionally at ca. 33.5 Ma and ending at ca. 27 Ma. Probable eolian sandstone of Oligocene age 483 m thick is also present in the subsurface of the Albuquerque Basin of the Rio Grande rift. The beginning of eolian deposition on the Colorado Plateau corresponds closely to the beginning of eolian (loessic) deposition...
Clastic and organic sediments exposed in two stream cutbanks above modern timberline in the headwaters of the Henrys Fork drainage record multiple episodes of fluvial, lacustrine and wetland deposition. The location of the upper Henrys Fork at the boundary between modern summer-wet/winter-dry and summer dry/winter-wet precipitation regimes suggests that changes in vegetation during the Holocene were due primarily to variations in growing-season temperature. A radiocarbon date of 9310 6 70 BP on a Salix fragment from the base of one exposure indicates that the upper reaches of the Henrys Fork were vegetated by riparian willows by the early Holocene. Four other dates on wood and bulk organics ranging up to 4070 6...
Understanding and modeling precipitation isotope (?18O and ?D) patterns for large regions of the globe requires quantifying processes governing continental-scale climatology and hydrology. In this study, we have evaluated the extent to which inclusion of monthly moisture source temperature and moisture source locations in the Rayleigh distillation model aid in reproducing the relationships between monthly time series of precipitation isotope (?18O) values and temperature across the contiguous United States. The steepest isotope-temperature slopes (0.5??0.6? ?18O/�C) and greatest ?18O value correlations with temperature (r2 = 0.5?0.8), derived from 5 continuous years of the data from the United States Network for...
thumbnail
The elevation history of Earth's surface is key to understanding the geodynamic processes responsible for the rise of plateaus. We investigate the timing of Colorado Plateau uplift by estimating depositional temperatures of Tertiary lake sediments that blanket the plateau interior and adjacent lowlands using carbonate clumped isotope paleothermometry (a measure of the temperature-dependent enrichment of 13C-18O bonds in carbonates). Comparison of modern and ancient samples deposited near sea level provides an opportunity to quantify the influence of climate and therefore assess the contribution of changes in elevation to the variations of surface temperature on the plateau. Analysis of modern lake calcite from 350...
thumbnail
The Colorado River is a crucial water source for millions of people in the Southwest. Warming temperatures, clearly documented in climate records for the Colorado River basin, are having an impact on the amount of annual streamflow yielded from rain and snow. Recent work has revealed that warming temperatures have played an increasingly important role over the past decades, both exacerbating droughts and dampening the effects of wet winters on high stream flows. Understanding and anticipating how warming temperatures will influence future water supply in the Colorado River basin is increasingly important for resource management, particularly in light of recent drought conditions. The overarching goals of this...
thumbnail
By collaborating with water managers and combining climate modeling and paleoclimate methods, the project team will incorporate prediction tools to assess risk of extreme wet/dry climate conditions for the next 10-15 years (i.e. decadal prediction). Our target area is the Wasatch Range Metropolitan Area that includes Salt Lake City one of the largest population centers within the Southern Rockies LCC. We will focus on projecting future water availability and quality with a specific goal for decadal prediction. The project team has partnered with numerous water agencies in the Wasatch Range who have made in-kind contributions towards this project. This partnership guarantees that the results will be disseminated,...
A quarry within the Cedar Mountain Formation in Mussentuchit Wash, Emery County, Utah, produced a fossil assemblage containing the remains of at least eight juvenile iguanodontid dinosaurs (Eolambia caroljonesa). The Cedar Mountain Formation lies stratigraphically between the Tithonian?Berriasian (Upper Jurassic) Brushy Basin Member of the Morrison Formation and the Cenomanian (Upper Cretaceous) Dakota Formation. Detailed stratigraphic, sedimentological, geochronological, palynological, and paleontological data have been collected along a measured section at the site of the Cifelli #2 Eolambia caroljonesa Quarry. These data provide a chronostratigraphic and a biostratigraphic framework for the Cedar Mountain Formation...
The Salt Lake City, Utah, region has a climate record dating from the mid-1800s that can be used to calibrate a tree ring record to climate and streamflows. A number of good candidate species for tree ring analysis include indigenous coniferous species that are signature species in tree ring analysis because their growth is sensitive to drought. However, these species represent different habitats. We will conduct controlled field studies to define the relationship between a suite of tree species native to the Wasatch range and drought stress and air temperature as well as to use tree ring data to understand and explain paleoclimate drought cycles and reconstruct streamflows in an innovative way. The research...


map background search result map search result map Influence of climate change and uplift on Colorado Plateau paleotemperatures from carbonate clumped isotope thermometry Back to the Future:  Innovative Tree Ring Analysis to Reconstruct Paleoclimate and Streamflows for Improved Urban Water Planning Under Climate Change - BOR Project, FY2011 The Chuska erg: Paleogeomorphic and paleoclimatic implications of an Oligocene sand sea on the Colorado Plateau Extent of Pleistocene Lakes in the Western Great Basin Core OL-92 from Owens Lake, southeast California WaterSMART: Building Decadal Prediction of Extreme Climate for Managing Water Supply in Intermountain West Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin The Chuska erg: Paleogeomorphic and paleoclimatic implications of an Oligocene sand sea on the Colorado Plateau WaterSMART: Building Decadal Prediction of Extreme Climate for Managing Water Supply in Intermountain West Influence of climate change and uplift on Colorado Plateau paleotemperatures from carbonate clumped isotope thermometry Extent of Pleistocene Lakes in the Western Great Basin Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin