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At least 1,423 records · Page 79Linked to original sources
USGS1985

Stream-sediment and panned-concentrate geochemical maps of the Buffalo Peaks Wilderness Study Area, Lake, Park, and Chaffee counties, Colorado

Under provisions of the Wilderness Act (Public Law 88-577, September 3, 1964), the U.S. Geological Survey and the U.S. Bureau of Mines have been conducting mineral surveys of areas selected for possible inclusion in the National Wilderness Preservation System. This report presents results of geochemical studies carried out in June and July, 1982, as part of the investigation of the Buffalo Peaks Wilderness Study Area, Colo. Stream-sediment and panned-concentrate samples were collected from about 80 sites on streams draining the study area. Analytical results and a sample locality map were published by Domenico and others (1984). The geologic and mineral resource potential maps of the study area were prepared by Hedlund and others (1983). The Buffalo Peaks Wilderness Study Area encompasses a major portion of the Mosquito Range, which is structurally part of the east flank of the north-northwest-trending Sawatch anticline. Bedrock in the west two-thirds of the study area is made up of Precambrian igneous and metamorphic rocks of the core of the anticline, whereas bedrock in the east one-third is mostly east dipping Paleozoic sedimentary rocks. In the vicinity of East and West Buffalo Peaks, the sequence of Paleozoic sedimentary rocks is covered by Tertiary extrusive rocks. Major faults generally run parallel to the north-northwest trend of the Arkansas River Valley, which is an expression of the Arkansas River segment of the Rio Grande depression, and the Sawatch anticline in the study area. Some faults are probably of late Precambrian age; major recurrent displacement is known to have occurred on most faults during Laramide time and in the Pliocene and Miocene. The study area is bounded by several areas of known mineralization (Hedl und and others, 1983). Vein and bedding replacement deposits of silver, zinc, and lead were mined from 1890 until about 1918 in the vicinity of Weston Pass (map A), on the northeastern border of the study area. Gold and silver were mined from about 1860 until about 1880 from veins in the Granite area (map A), on the northwestern border of the study area; minor prospecting activity continues today. From 1935 to 1937, veins of gold, silver, and base metals were mined in the vicinity of Fourmile Creek, on the southwestern border of the study area (map A). Recently, active uranium prospecting has been taking place in the vicinity of the Middle Fork of Salt Creek, on the southeastern border of the study area (map A).

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USGS1985

Maps showing water geochemistry of the Buffalo Peaks Wilderness Study Area, Lake, Park, and Chaffee Counties, Colorado

This report presents results of geochemical studies carried out in June and July of 1982 in the Buffalo Peaks Wilderness Study Area, Colo. (see index map). Samples of water were collected from 84 streams and 18 springs draining the study area. Tabulations of the analyses and a sample locality map are in Ficklin and others (1984). The geochemistry of stream sediments and panned concentrates of the study area is in Nowlan and Gerstel (1985). The geology of the study area and vicinity is in Hedlund (1985). The mineral resource potential of the study area is described in Hedlund and others (1983). This report (1) assists in the assessment of the mineral resource potential of the Buffalo Peaks Wilderness Study Area; and (2) compares analyses of water samples with analyses of stream-sediment and panned-concentrate samples (Nowlan and Gerstel, 1985).

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USGS1985

Mineral resource potential map of the Fossil Ridge Wilderness Study Area, Gunnison County, Colorado

Parts of the Fossil Ridge Wilderness Study Area have a high resource potential for gold and silver in small deposits, uranium in medium-size deposits, and high-calcium limestone in large deposits. Parts have a moderate to high potential for uranium, thorium, and light rare-earth elements in small- to medium-size deposits, a moderate potential for copper, lead, and zinc in small deposits, a low potential for molybdenum in small deposits, and an unknown potential for molybdenum in deposits of unknown size. Parts of the area have a low potential for cobalt, chromium, tungsten, beryllium, boron, and tin in small deposits. And, depending on the extraction of precious metals, parts of the area could have a low potential for arsenic in small deposits. Tungsten, rare-earth elements, and tin could not be considered resources except for coexisting base metals, thorium, and uranium. Areas that immediately adjoin the Fossil Ridge Wilderness Study Area have a high potential for molybdenum in large deposits, lead in medium-size deposits, and zinc -in small- to medium-size deposits. Depending on the extraction of base metals, parts of the adjoining areas could have a low resource potential for bismuth and cadmium as byproducts in medium-size deposits.

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USGS1985

Gravity and aeromagnetic maps of the Maroon Bells-Snowmass Wilderness and additions, Pitkin and Gunnison counties, Colorado

Aeromagnetic and complete Bouguer gravity anomaly maps have been prepared for the Maroon Bells-Snowmass Wilderness and additions, near Aspen, Colorado. An extreme gravity low, which may be indicative of mineralization, occurs over the White Rock pluton in the southeastern part of the study area. Modeling of the gravity and magnetic anomalies shows that the Sopris, Snowmass, and White Rock plutons are probably all stocks connected to a single batholith at depth. Both Sopris and Snowmass stocks seem to be shaped like spikes bristling out of this common batholith; the Snowmass spike is vertical, the Sopris spike is inclined. The Snowmass spike has a westward-extending flange, possibly related to the Elk Range thrust zone. The White Rock stock is a massive conical lump on top of the underlying batholith. Its complicated aeromagnetic signature seems partly due at least two magnetically distinct regions, which may represent altered zones or separate intrusions within the stock. These regions occur under the Conundrum Creek and East Maroon Creek valleys and may represent favorable locations for mineralization.

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USGS1985

Map showing gravel-bearing surficial deposits and basaltic rocks near Trinidad, Las Animas County, Colorado

This map of the Trinidad area is considered to be a special purpose map, as it shows only gravel-bearing alluvial deposits laid down by streams and a series of stacked lava flows erupted from local volcanoes. Nongravelly surficial deposits and Cretaceous bedrock, which would be on a standard geologic map, are not shown. The map has two purposes: a scientific one to show the distribution, character, and age of the alluvial deposits and a practical one, to map the distribution of deposits of gravel and crushable rock for use as construction materials.

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USGS1985

Runoff characteristics and washoff loads from rainfall-simulation experiments on a street surface and a native pasture in the Denver metropolitan area, Colorado

Rainfall-runoff simulation studies were conducted in conjunction with the Denver Regional Urban Runoff Program to: (1) Compare runoff characteristics from two different intensities of simulated rainfall on street-surface plots, (2) document a first flush of constituent washoff loads in runoff from 1,000-sq-ft street-surface plots, (3) compare runoff characteristics from the street surface plots with those from a 69-acre urban mixed land use subjected to natural rainfall, (4) perform statistical analysis of washoff loads, and (5) compare quantity and quality of runoff from 400-sq-ft plots of native pasture subjected to simulated rainfall and from a 405-acre basin of native pasture subjected to natural rainfall. Experiments on the street surface showed that higher intensity simulated rainfall produced a higher percentage of runoff than lower intensity rainfall, and a first flush of constituent loads occurred for most constituents. The event mean constituent concentrations in the street-surface runoff from simulated storms were generally much smaller than those in the runoff from an adjacent urban basin. Simulated rainfall in small native pasture plots produced runoff-to-rainfall ratios similar to runoff-to-rainfall ratios from a larger native pasture subject to natural rainfall. (USGS)

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USGS1985

Calibration procedure for a daily flow model of small watersheds with snowmelt runoff in the Green River coal region of Colorado

A calibration procedure was developed for the U.S. Geological Survey 's Precipitation-Runoff Modeling System for watersheds in which snowmelt is the major contributor to runoff. The model uses daily values of air temperature and precipitation as input and the output is mean daily discharge. The procedure appears sufficient to calibrate both streamflow volume and the timing of mean daily discharge if other model parameters are reasonably estimated. Model structure and sensitivity analysis suggest that one of the most important parameters is the available water-holding capacity of the soil (SMAX). Changing this parameter through a series of iterations, the calibration procedure minimizes the error between observed and predicted annual discharge. The calibration suggests that the single parameter SMAX may be sufficient for optimizing both the volumes and the timing of runoff, assuming other model parameters are adequately estimated. Additional optimization on parameters sensitive to timing does not appear to improve prediction. This indicates that these parameters were estimated accurately prior to calibration. Further investigation is needed on more watersheds to determine SMAX 's ability to calibrate volume and timing with a constant set of other model parameter values.

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USGS1985

A summary of urban runoff studies in the Denver Metropolitan area, Colorado

The Denver metropolitan area has been the subject of urban-runoff studies for several years. The first studies, started in about 1968, usually were concerned only with the quantity of urban runoff. In 1974, studies were begun that included both quantity and quality of urban runoff. In 1979, Denver was selected as one of the cities to be included in the Nationwide Urban Runoff Program. The Denver study was called the Denver Regional Urban Runoff Program and was a cooperative study between the Denver Regional Council of Governments and the U.S. Geological Survey. This report presents the major conclusions of the pre-Denver Regional Urban Runoff Program studies and a summary of the various elements of the Denver Regional Urban Runoff Program. The report summarizes and references urban-runoff studies in the Denver metropolitan area and is a reference guide for planners and other persons interested in urban runoff.

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USGS1985

Discharge and water quality of springs in Roan and Parachute Creek basins, northwestern Colorado, 1981-83

This report is a compilation and interpretation of discharge, water-quality, and radiochemical data collected at springs in the oil-shale regions of Roan and Parachute Creek basins, Colorado, from 1981 to 1983. Springs located on upland plateaus and ridges are mixed-cation bicarbonate water types with 216 to 713 milligrams per liter dissolved solids. Calcite and dolomite dissolution are dominant chemical reactions in upland springs. Springs located in the canyons contain greater concentrations of sodium and sulfate and have 388 to 3,970 milligrams per liter dissolved solids. Gypsum dissolution is an important chemical reaction in canyon spring water. The only trace constituents with mean concentration greater than 10 micrograms per liter in the study area were barium, boron, lithium and strontium. None of the canyon springs investigated represent discharge from the lower aquifer in the Green River Formation. Analysis of chemical and discharge data for streams in the Roan Creek drainage showed evidence of lower-aquifer discharge into the canyons. Springs located near an oil-shale mine or processing plant could be used for monitoring groundwater quality and quantity. Bicarbonate, fluoride, arsenic, boron, lithium, mercury, ammonia, and organic carbon may be chemical indicators of mine or process-water contamination of shallow aquifers near an oil-shale plant or mine.

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USGS1985

The Dakota aquifer near Pueblo, Colorado: Faults and flow patterns

The Dakota Sandstone and the underlying Purgatoire Formation consisting of the Glencairn Shale and Lytle Sandstone Members form a board outcrop at the southeastern margin of the Canon City Embankment. The two formations form the Dakota aquifer, which supplies water to many domestic, stock, and irrigation wells in addition to a few municipal wells in the 12-township study area. Five large faults and several small faults, all apparently of high angle, are found in the study area. Analysis of water levels and water quality shows that parts of some of these faults restrict the flow of groundwater in the Dakota aquifer. Lithology of the rocks, particularly in the Dakota Sandstone and in the Glencairn Shale Member, is extremely variable. The lithology appears to affect the flow regime, possibly by determining how a particular segment of a fault affects flow. (USGS)

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