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Research about Colorado, Wyoming

Source-linked reports with geographic coverage including Colorado, Wyoming.

At least 55 records · Page 3Linked to original sources
USGS1989

Zircon geochronology of Precambrian rocks in southeastern Wyoming and northern Colorado

Archean gneisses and Early Proterozoic metasedimentary rocks of the Wyoming Province are separated from Proterozoic eugeoclinal metamorphic rocks by a major east-west–trending shear zone called the Cheyenne belt. U-Pb zircon ages of Archean tonalites north of the Cheyenne belt denote an intrusive event at 2,700 Ma. Detrital zircons from Proterozoic metasedimentary rocks north of the Cheyenne belt define an apparent age of 2,450 Ma for the source rock, similar to an age of 2,430 Ma obtained for a local granite. A metagabbro plug, which intruded the metasedimentary rocks about 2,100 Ma, constrains their deposition within this 350 m.y. period. Ages for key units just south of the Cheyenne belt in Wyoming delineate at least three magmatic events at 1,780; 1,750; and 1,625 Ma. Ages for large plutons in the northern Colorado area define pulses of granodioritic to granitic intrusions at approximately 1,720 and 1,670 Ma. A U-Pb zircon age of 1,792 ± 15 Ma for a Proterozoic metavolcanic rock in the Sierra Madre is greater than ages reported for other Proterozoic metavolcanic rocks in the U.S. Rockies. However, ages for Proterozoic plutons in southeastern Wyoming are similar to other ages for plutonism and volcanism for rocks exposed in the central Colorado Rockies and are coeval with suturing of Proterozoic crust with the Archean Wyoming Province along the Cheyenne belt. Although at present the accretionary history for these Early Proterozoic rocks is not well understood, it is evident that there exists a progressive decrease in age for volcanism as well as plutonism from north to south.

Colorado, Wyoming↗
USGS1987

Hydrology of area 59, northern Great Plains and Rocky Mountain coal provinces, Colorado and Wyoming

Hydrologic information and analysis aid in decisions to lease federally owned coal and to prepare necessary Environmental Assessments and Impact Study reports. This need has become even more critical with the enactment of Public Law 95-87, the "Surface Mining Control and Reclamation Act of 1977." This act requires an appropriate regulatory agency to issue permits, based on the review of permit-application data to assess hydrologic impacts. This report, which partially fulfills this requirement, is one in a series of nationwide coal province reports that present information thematically, through the use of a brief text and accompanying maps, graphs, charts, or other illustrations for single hydrologic topics. The report broadly characterizes the hydrology of Area 59 in north-central Colorado and southeastern Wyoming. The report area, located within the South Platte River basin, covers a 16,000-square-mile area of diverse geology, topography, and climate. This diversity results in contrasting hydrologic characteristics. The South Platte River, the major stream in the area, and most of its tributaries originate in granitic mountains and flow into and through the sedimentary rocks of the Great Plains. Altitudes range from less than 5,000 feet to more than 14,000 feet above sea level. Precipitation in the mountains may exceed 40 inches annually, much of it during the winter, and produces deep snowpacks. Snowmelt during the spring and summer produces most streamflow. Transmountain diversion of water from the streams on the western slope of the mountains also adds to the streamflow. Precipitation in the plains is as little as 10 inches annually. Streams that originate in the plains are ephemeral. Streamflow quality is best in the mountains, where dissolved-solids concentrations are generally small. Concentrations increase in the plains as streams flow through sedimentary basins, and as urbanization and irrigation increase. The quality of some mountain streams is affected by drainage from previous metalmining areas, as indicated by greater trace-element concentrations and smaller pH values. However, the large trace-element concentrations decrease rapidly downstream from the metal-mining areas. Because the climate is semiarid in most of the area, the soils are not adequately leached; therefore, flows in ephemeral streams usually have larger concentrations of dissolved solids than flows in perennial streams. Ground water is available throughout the area; yields range from less than 0.1 gallons per minute in the fractured granite aquifer in the mountains to more than 2,000 gallons per minute in the alluvial aquifer of the South Platte River valley. Major bedrock aquifers in order of decreasing age are the Laramie-Fox Hills, Arapahoe, Denver, and Dawson; these aquifers are used for municipal, domestic, and livestock supplies. Alluvial aquifers supply the high-yield irrigation wells. The best quality ground water is found at the center of the major bedrock aquifers, where dissolved-solids concentrations are less than 200 milligrams per liter. The poorest-quality water is usually found near the edges of these aquifers. Water in the coal-bearing Laramie and Denver Formations is locally affected by coal deposits, causing dissolved-solids concentrations to be relatively large. Only one coal mine is now operating in Area 59, the Coors Energy Company surface coal mine, which produced 100,000 short tons of subbituminous coal from the Upper Cretaceous Laramie Formation in 1982. Past coal-mining operations removed more than 130 million tons of coal and lignite from Area 59,99 percent of which came from underground mines. The largest coal production was in Weld and Boulder Counties, Colorado. Hydrologic problems related to surface mining are erosion, sedimentation, decline in water levels, disruption of aquifers, and degradation of water quality. Because the semiarid mine areas have very little runoff, and the major streams have large buffer and dilution capacities, the effects of mining on surface water is minimal. However, effects on ground water may be much more severe and long-lasting.

Colorado, Wyoming↗
USGS1983

Biostratigraphic correlation chart of some Upper Cretaceous rocks from the Lost Soldier area, Wyoming to west of Craig, Colorado

This chart depicts the time-stratigraphic relations of some Upper Cretaceous rocks along the eastern and southeastern margins of the Greater Green River Basin, south-central Wyoming and northwestern Colorado. The purpose of this report is to release a preferred set of correlations based upon marine mollusk biostratigraphy. The senior author, with the help of B. E. Law, has acquired, synthesized, compiled, and interpreted data from various sources. These include selected published documents (see "References Cited") and unpublished reports of fossil identifications by W. A. Cobban who examined collections made by the late J. R. Gill. Numerous measured sections of Gill's were also utilized. It must be emphasized that all interpretations on this chart are based on information obtained from these sources and the senior author has yet to substantiate these correlations in the field. Not all data from the area of this study is included herein because it is either repetitive in nature or its reliability is uncertain. This uncertainty is due to the ambiguity inherent in both fossil identification and stratigraphic interpretation. Questionable unpublished material has been omitted while published data which is inconsistent with the senior author's correlations may be found in the footnotes portion of this report. The rock units are assigned to a range of ammonites that have been related to an absolute time scale. The ammonite zonation and age boundaries are adapted from Obradovich and Cobban (1975). "D" numbers are provided for each geographic locality where fossils were collected and described by personnel of the U.S. Geological Survey. These fossils may be accessed at the offices of the Survey in Lakewood, Colorado.

Colorado, Wyoming↗
USGS1983

Hydrology of area 54, northern Great Plains, and Rocky Mountain coal provinces, Colorado and Wyoming

A nationwide need for information characterizing hydrologic conditions in mined and potential mine areas has become paramount with the enactment of the Surface Mining Control and Reclamation Act of 1977. This report, one in a series covering the coal provinces nationwide, presents information thematically by describing single hydrologic topics through the use of brief texts and accompanying maps, graphs, or other illustrations. The summation of the topical discussions provides a description of the hydrology of the area. Area 54, in north-central Colorado and south-central Wyoming, is 1 of 20 hydrologic reporting areas of the Northern Great Plains and Rocky Mountain coal provinces. Part of the Southern Rocky Mountains and Wyoming Basin physiographic provinces, the 8,380-square-mile area is one of contrasting geology, topography, and climate. This results in contrasting hydrologic characteristics. The major streams, the North Platte, Laramie, and Medicine Bow Rivers, and their principal tributaries, all head in granitic mountains and flow into and through sedimentary basins between the mountain ranges. Relief averages 2,000 to 3,000 feet. Precipitation in the mountains may exceed 40 inches annually, much of it during the winter, which produces deep snowpacks. Snowmelt in spring and summer provides most streamflow. Precipitation in the basins averages 10 to 16 inches annually, insufficient for sustained streamflow; thus, streams originating in the basins are ephemeral. Streamflow quality is best in the mountains where dissolved-solids concentrations generally are least. These concentrations increase as streams flow through sedimentary basins. The increases are mainly natural, but some may be due to irrigation in and adjacent to the flood plains. In the North Platte River, dissolved-solids concentrations are usually less than 300 milligrams per liter; in the Laramie and the Medicine Bow Rivers, the concentrations may average 500 to 850 milligrams per liter. However, water-quality stations on the Laramie and the Medicine Bow Rivers are farther removed from the mountain sources than the stations in the North Platte drainage. Because of the semiarid climate of the basins, soils are not adequately leached. Consequently, flow in ephemeral streams usually has a larger concentration of dissolved solids than that in perennial streams, averaging 1,000 to 1,600 milligrams per liter. Aquifers containing usable ground water are combined into three groups: (1) consolidated and unconsolidated non-coal-bearing Quaternary and Upper Tertiary deposits, (2) Mesozoic and Paleozoic sedimentary rocks, and (3) Lower Tertiary and Upper Cretaceous sedimentary rocks containing coal. These aquifers are used for municipal, domestic, irrigation, and stock supplies. Well yields range from about 5 to 1,000 gallons per minute, and depend on type of aquifer, saturated thickness, and degree of fracturing. The best quality ground water usually comes from the non-coal-bearing Quaternary and Upper Tertiary rocks or the Mesozoic and Paleozoic rocks; often it is dominated by calcium and bicarbonate ions. The coal-bearing formations have a large variability in water chemistry; dominant ions may be bicarbonate or sulfate and sodium, calcium, or magnesium. Dissolved-solids concentrations are generally larger than in the former two groups. The U.S. Geological Survey operates a network of hydrologic stations to observe the streamflow and groundwater conditions. This network currently includes 31 surface-water stations and 35 observation wells; information is available for many other sites observed in the past. Data available include rate of flow, water levels, and water quality; much of the data are available in published reports or from computer storage through the National Water Data Exchange (NAWDEX) or the National Water Data Storage and Retrieval System (WATSTORE). Five formations of Late Cretaceous and early Tertiary age contain coal.

Colorado, Wyoming↗
USGS1981

Assessment of impacts of proposed coal-resource and related economic development on water resources, Yampa River basin, Colorado and Wyoming: A summary

Expanded mining and use of coal resources in the Rocky Mountain region of the western United States will have substantial impacts on water resources, environmental amenities, and social and economic conditions. The U.S. Geological Survey has completed a 3-year assessment of the Yampa River basin, Colorado and Wyoming, where increased coal-resource development has begun to affect the environment and quality of life. Economic projections of the overall effects of coal-resource development were used to estimate water use and the types and amounts of waste residuals that need to be assimilated into the environment. Based in part upon these projections, several physical-based models and other semiquantitative assessment methods were used to determine possible effects upon the basin's water resources. Depending on the magnitude of mining and use of coal resources in the basin, an estimated 0.7 to 2.7 million tons (0.6 to 2.4 million metric tons) of waste residuals may be discharged annually into the environment by coal-resource development and associated economic activities. If the assumed development of coal resources in the basin occurs, annual consumptive use of water, which was approximately 142,000 acre-feet (175 million cubic meters) during 1975, may almost double by 1990. In a related analysis of alternative cooling systems for coal-conversion facilities, four to five times as much water may be used consumptively in a wet-tower, cooling-pond recycling system as in once-through cooling. An equivalent amount of coal transported by slurry pipeline would require about one-third the water used consumptively by once-through cooling for in-basin conversion. Current conditions and a variety of possible changes in the water resources of the basin resulting from coal-resource development were assessed. Basin population may increase by as much as threefold between 1975 and 1990. Volumes of wastes requiring treatment will increase accordingly. Potential problems associated with ammonia-nitrogen concentrations in the Yampa River downstream from Steamboat Springs were evaluated using a waste-load assimilative-capacity model. Changes in sediment loads carried by streams due to increased coal mining and construction of roads and buildings may be apparent only locally; projected increases in sediment loads relative to historic loads from the basin are estimated to be 2 to 7 percent. Solid-waste residuals generated by coal-conversion processes and disposed of into old mine pits may cause widely dispersed ground-water contamination, based on simulation-modeling results. Projected increases in year-round water use will probably result in the construction of several proposed reservoirs. Current seasonal patterns of streamflow and of dissolvedsolids concentrations in streamflow will be altered appreciably by these reservoirs. Decreases in time-weighted mean-annual dissolved-solids concentrations of as much as 34 percent are anticipated, based upon model simulations of several configurations of proposed reservoirs. Detailed statistical analyses of water-quality conditions in the Yampa River basin were made. Regionalized maximum waterquality concentrations were estimated for possible comparison with future conditions. Using Landsat imagery and aerial photographs, potential remote-sensing applications were evaluated to monitor land-use changes and to assess both snow cover and turbidity levels in streams. The technical information provided by the several studies of the Yampa River basin assessment should be useful to regional planners and resource managers in evaluating the possible impacts of development on the basin's water resources.

Colorado, Wyoming↗
USGS1980

Effective and bankfull discharges of streams in the Yampa River basin, Colorado and Wyoming

The effective discharge is defined as the increment of discharge that transports the largest fraction of the annual sediment load over a period of years. Increments of the average annual total sediment load transported by various discharges were calculated by the flow-duration, sediment-transport-curve method for 15 gaging stations in the Yampa River basin of Colorado and Wyoming. A total sediment-transport curve was constructed for each gaging station by adding measured instantaneous suspended-sediment discharges to bedload-sediment discharges computed by the Meyer-Peter and Mueller relation. The streamflow durations were compiled from the respective gaging-station records. The quantity of sediment transported by discharges having various frequencies may be computed by combining these two relations. The 15 gaging stations had diverse hydraulic and sediment characteristics. Contributing drainage area ranged from 51.8 to 9,960 km 2 , and mean-annual discharge ranged from 0.040 to 43.9 m 3 /s. The median diameter of bed material ranged from 0.4 to 86 mm. Mean-annual sediment load from the drainage basins studied ranged from 500 to 1.3·10 6 metric tons per year. The effective discharges at the 15 gaging stations were equaled or exceeded on the average of between 1.5 days per year (0.4% of the time) and 11 days per year (3.0% of the time). The recurrence interval of the effective discharges ranged from 1.18 to 3.26 yr. on the annual flood series. To compare the effective discharge with the bankfull discharge, cross-sections were surveyed in a self-formed reach of the channel in the vicinity of each gaging station. The bankfull discharge was defined as the discharge which filled the channel to the level of the floodplain. At all gaging stations, the effective discharge and the bankfull discharge were nearly equal. Thus, the stream channels appear to be adjusted to their effective discharge.

Colorado, Wyoming↗
USGS1978

Minor and trace element contents of kimberlites of the Front Range, Colorado and Wyoming

Since 1960 about 90 separate occurrences of kimberlite have been discovered in the Front Range of northern Colorado and southern Wyoming, and in the Laramie Range, Wyoming (e.g., McCallum, Eggler, and Burns, 1975; McCallum, Eggler, Coopersmith, Smith, and Mabarak, 1977; Smith and others, 1977 and in press). All but two of the known kimberlites occur in the Colorado-Wyoming State Line district or in the Iron Mountain, Wyoming, district (fig. 1). A single kimberlite dike is located at Estes Park, Colo., and a small pipe-like body occurs immediately west of Boulder, Colo. (fig. 1). Continuous research for the purpose of locating and characterizing kimberlite in the Front Range has been conducted from 1960 to the present, primarily by M. E. McCallum, D. H. Eggler, and Colorado State University graduate students. The Boulder kimberlite specifically has been studied by Kridelbaugh and others, 1972; Kridelbaugh and Meyer, 1973; Moyer and Kridelbaugh, 1977; and Boctor and Meyer, 1977. As part of the overall kimberlite project directed by M. E. McCallum, the U.S. Geological Survey has provided the whole-rock minor and trace element analyses reported herein. Although primarily semiquantitative, the analyses show that minor and trace element contents of kimberlites in the Front Range are similar to those of kimberlites elsewhere in the world.

Colorado, Wyoming↗
USGS1976

An environmental assessment of impacts of coal development on the water resources of the Yampa River basin, Colorado and Wyoming; Phase I work plan

Coal resources of the western United States are being developed at ever-increasing rates, causing concerns of the effects of mining and associated activities on the environment. The Yampa River basin in northwestern Colorado and south-central Wyoming is undergoing economic development of its coal, oil and gas, and uranium resources. The Yampa River basin assessment is a 21-year program of the U.S. Geological Survey. It is designed primarily to assess the availability and quality of the basin's water resources. The basin assessment also will evaluate potential environmental and selected socioeconomic impacts of energy-resource development plans proposed by mining and power companies. This report serves as a project work plan for the basin assessment's first-phase work activities. Economic development in the Yampa River basin will result in higher levels of residuals (noneconomic byproducts) being discharged into the environment. Residuals-management encompasses the technological and economic interrelationships that should be considered in order to comply with Federal and State environmental-control regulations regarding air quality, water quality, and disposal of solid wastes. The basin assessment, the first phase that is described by this report, is designed to provide Federal, State, and local decision-makers with the basic environmental information needed to formulate and to evaluate policies for the development of energy resources. The techniques applied and conclusions reached in the Yampa River basin assessment should aid similar studies of other energy-rich basins in the western United States.

Colorado, Wyoming↗
USGS1976

An environmental assessment of impacts of coal development on the water resources of the Yampa River basin, Colorado and Wyoming; Phase II work plan

Coal resources of the western United States are being developed at everincreasing rates, causing concerns of the effects of mining and associated activities on the environment. The Yampa River basin in northwestern Colorado and south-central Wyoming is undergoing economic development of its coal, oil and gas, and uranium resources. By 1990, the annual coal mining in the basin is expected to increase to 20 million tons (18 million tonnes), or more than 4 times the 1975 level. As a result, the regional population is expected to at least double over the same period. Power-generation plants fueled by coal are being expanded or constructed in the basin and will have a combined generating capacity of nearly 1,200 megawatts by 1980. The Yampa River Basin Assessment is a 2-year program of the U.S. Geological Survey. It is designed primarily to assess the availability and quality of the basin's water resources. The basin assessment also will evaluate potential environmental and selected socioeconomic impacts of energy-resource development plans proposed by mining and power companies. This report serves as a project work plan for the basin assessment. It describes the program objectives, and the various approaches of analysis and evaluation. Environmental studies are outlined for analyzing both the direct effects of various proposals regarding coal mining, transportation, and conversion, and the secondary effects resulting from increased population and urban growth. Economic development in the Yampa River basin will generate higher levels of residuals which are discharged into the environment. Residuals-management encompasses the technological and economic interrelationships that should be considered to comply with Federal and State environmental-control regulations regarding air quality, water quality, and disposal of solid wastes. The basin assessment described by this report is designed to provide Federal, State, and local decision-makers with the basic environmental information needed to formulate and to evaluate policies for the development of energy resources. The techniques applied and conclusions reached in the Yampa River Basin Assessment should aid similar studies in other energy-rich basins in the western United States.

Colorado, Wyoming↗