USGS Science⌕ Search

SEARCH · USGS Science

Results for “Preliminary Report”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
USGS1980

Preliminary report on the mineral resources of the Powderhorn Instant study area, Gunnison and Hinsdale counties, Colorado

The Powderhorn Instant Study Area covers approximately 51,000 acres of land under BLM administration located about 80 km (50 mi) southwest of Gunnison, Colorado. A mineral resource survey, made in 1979 by the U.S. Geological Survey and the U.S. Bureau of Mines, indicates that both the mineral potential and the energy potential for the Powderhorn Instant Study Area are low. This report is based on geologic and geochemical investigations, examination of prospects, and an aeromagnetic survey. Spectrographic analyses were made of approximately 120 stream-sediment and rock samples. No mining districts are located within the study area.

Colorado↗
USGS1980

Preliminary report on the geology of the continental slope adjacent to OCS Lease Sale 55, eastern Gulf of Alaska: Petroleum resource implications

Forty samples of Tertiary and Cretaceous outcrop or suspected outcrop were dredged along the 250-km-long northwest-trending continental slope between long 138°00' W. and 142°30' W. These samples, from water depths of 3,150 m to 200 m, combined with seismic reflection data, identify seven rock units in apparently normal stratigraphic position. From oldest to youngest they are: Unit A: Hard graywacke, argillite, and possible intrusive rocks of inferred Late Cretaceous age that crop out in the eastern part of the slope and probably underlie much of the Fairweather Ground. Unit B: At least 900 m of sandstone, conglomerate, shale, and subordinate basaltic volcanic rocks west of Yakutat Seavalley between 142° W. and 143° W. that is not dated but is probably of late Paleocene to early Eocene age. Unit C: 1,300 m of basaltic flow and pyroclastic rocks with associated clastic marine sedimentary rocks that makes up much of the rugged lower slope throughout the area. This sequence is largely, or entirely, of early Eocene age. Unit D: Up to 2,100 m of early and middle Eocene sandstone, conglomerate, siltstone, and tuffaceous organic-rich shale that partly overlies, and partly intertongues with, the volcanic unit. Unit E: 800 m of early to late Eocene and early Oligocene(?) organic-rich shale, tuffaceous shale, siltstone, and sandstone that partly intertongues with, and partly overlies units C and D. Unit F: 300+ m of siltstone, at least in part of late Oligocene age, that crops out locally along the upper slope where it unconformably overlies Unit E. Unit G: Up to 2,000 m of late Cenozoic (middle Miocene? and younger) clastic sedimentary rocks including abundant glaciomarine deposits that unconformably overlie all the older units. The early Tertiary sequence sampled on the continental slope differs strikingly in lithology and structure from coeval rocks exposed onshore or penetrated in unsuccessful exploratory wells on the adjacent mainland. Units B, D, and E include abundant source rocks that have undergone a thermal history resulting in local generation of hydrocarbons. Sandstones from Units D and E locally have secondary porosities up to 31 percent and permeabilities to 36 md. Seismic reflection data indicate that the sequence with the most favorable source and reservoir potential (Units B, D, E) dips northeastward beneath OCS Lease Sale 55 where it could be a favorable exploratory target if involved in suitable traps. Young anticlinal folds are not present, but other important traps are likely to include drape structures, horsts, and faults within the early Tertiary sequence and pinchouts, fault traps, or combination structural/stratigraphic traps along the northeastern margin of the early Tertiary basin.

Alaska↗
USGS1980

Channel erosion and sediment transport in Pheasant Branch basin near Middleton, Wisconsin; a preliminary report

The purpose of this 5-year study is to (1) evaluate the sediment transport, streamflow characteristics, and stream-channel morphology, (2) relate the above to land-use practices; and (3) evaluate the effect that changes in land-use practices will have on Pheasant Branch basin near Middleton, Wis. This report presents findings of sediment transport, streamflow characteristics, and stream-channel morphology from the first year of the study and documents historical erosion. The study is being conducted by the U.S. Geological Survey in cooperation with the city of Middleton and the Wisconsin Geological and Natural History Survey. Pheasant Branch, a tributary to Lake Mendota, drains 23.1 square miles of glacial drift. Channel erosion is severe within Middleton, requiring extensive use of erosion-control structures. Occasionally, channel dredging near the mouth and into Lake Mendota is required for boating. Comparison of stream-channel surveys of 1971 and 1977 shows the lowest part of the channel lowered 3 to 4 feet at some sites in the urban reach from U.S. Highway 12 downstream to Century Avenue. Downstream from Century Avenue, channel width increased from about 35 to 48 feet and channel cross-section area increased about 86 percent. A survey of Pheasant Branch in 1971 provided data for quantification of stream-channel changes since that time. Six erosion-control structures previously installed appear to have had some benefit in controlling head cutting in the channel. (USGS).

Wiscoonsin↗
USGS1980

A preliminary report of the geohydrology of the Mississippi salt-dome basin

The U.S. Department of Energy is investigating the suitability of salt domes in the Mississippi salt-dome basin as repositories for storing radioactive wastes. The Department of Energy has requested that the U.S. Geological Survey describe the groundwater hydrology of the Mississippi salt-dome basin, giving special attention to direction and rate of movement of water. In this first part of a continuing investigation the data obtained from one year of extensive literature search and data compilation are summarized. The regional groundwater hydrology in the salt-dome basin is defined with respect to (1) groundwater flow, (2) facies changes, (3) geological structure, (4) recharge and discharge, (5) freshwater-saltwater relations, and (6) identification of localities where additional data are needed. From the 50 piercement-type salt domes in the Mississippi salt-dome basin three domes (Richton, Cypress Creek, and Lampton) were selected for more intensive study. To further evaluate the geohydrology of Richton, Lampton, and Cypress Creek domes as possible sites for storage of radioactive waste, an intensive geohydrologic study based on a comprehensive test drilling program near the domes is planned. (USGS)

Mississippi↗
USGS1982

Preliminary report on the geology and gold mineralization of the Gold Basin-Lost Basin mining districts, Mohave County, Arizona

The Gold Basin-Lost Basin mining districts are adjacent to each other in northwestern Arizona, south of Lake Mead, and just west of the Grand Wash Cliffs. Most recorded production from lode deposits is credited to mines in the Gold Basin district, which is in the southern White Hills, whereas the bulk of the placer production has been from placers worked along the eastern flank of the Lost Basin range, about 16 km to the northeast across Hualapai Valley. Gold in quartz veins apparently was first discovered in the 1870's. Recorded production from the districts between 1901 and 1942 includes 13,508 oz gold and 6,857 oz silver, and this recorded production has a dollar value of about $359,000 of which 98 percent is credited to gold. Most known occurrences of lode gold in the districts are associated with widespread quartz-cored pegmatite-vein systems, presumably emplaced episodically during Proterozoic X, Proterozoic Y, and Late Cretaceous time into Proterozoic X metamorphic and igneous rocks. The bulk of the veins apparently were emplaced during the Late Cretaceous, and they were localized along both high- and low-angle structures in the Proterozoic X terrane. These veins appear to be associated genetically with presumably Late Cretaceous, two-mica magmatism. A Late Cretaceous two-mica monzogranite crops out in an approximately 4 to 5 km 2 area in the southern part of the Gold Basin district and includes some facies of episyenite. Some gold is found also in small episyenitic alteration pipes, or in veins caught up tectonically along a regionally extensive, low-angle detachment surface which crops out prominently in the southern White Hills, and has been traced for at least 30 km along the western flank of the White Hills. Hydrothermal micas from selected veins in the districts give K-Ar ages of 822, 712, 69, 68, and 65 m.y. (million years), and from the pipes, ages of 130 and 127 m.y. The oldest ages (822 and 712 m.y.) presumably reflect resetting of veins that probably were emplaced penecontemporaneous with emplacement of the 1,400-m.y. granite of Gold Butte, which crops out just to the north of Lake Mead. The latter ages (130 and 127 m.y.) must reflect either the presence of excess radiogenic argon in the hydrothermal environment of the evolving pipes, or contamination of the dated mineral separates by Proterozoic mica and (or) feldspar. Primary white mica from the two-mica monzogranite gives a K-Ar age of 72 m.y.. Most occurrences of gold in the veins and pipes probably reflect either remobilization of gold from gold-bearing, near-surface Proterozoic source areas, or anatectic incorporation of gold into Late Cretaceous, two-mica magmas from very deep gold-bearing Proterozoic sources. Deposition of gold occurred in a mesothermal environment during the galena-, chalcopyrite-, ferroan-carbonate-bearing stages of the veins. Homogenization studies of fluid inclusions prominent in the veins and pipes yield temperatures mostly in the range 150 to 280°C. Early-stage, trapping temperatures at the pipes probably were about 330°C and pressures in the range 500 to 700 bars can be inferred. Fluids were moderately saline, mostly 4 to 16 weight percent NaC1 equivalent, nonboiling, and also contain appreciable amounts of carbon dioxide and, in places, fluorine. Such fluids associated with the deposition of gold in these districts largely bridge the fluid composition interval between many other epithermal precious-metal and porphyry coper deposits. Approximately 350 compositional analyses obtained from native-gold samples from 20 mines in the Gold Basin district and 48 veins in the Lost Basin district show silver contents that range from 6 to approximately 50 weight percent, and copper from 0.01 to 0.5 weight percent. Metal zonation and possible relation to a porphyry copper system at depth can be inferred from some of these chemical data. The differences in the composition of placer gold from 24 occurrences in the Lost Basin district from that of nearby lode sources suggest that other sources contributed gold to the placers or that locally derived grains were enriched by oxidation and weathering of the lodes.

Arizona↗
USGS1981

Preliminary report on geophysics ground follow-up of the 1977 airborne survey in the Wadi Bidah District, Kingdom of Saudi Arabia

Reconnaissance geologic and geochemical sampling was made during the 1978 field season at most of the 50 or so electromagnetic anomalies detected in the 1977 airborne electromagnetic (AEM) survey of the Wadi Bidah district. These Phase 1 studies also included reconnaissance geophysical traverses of nine of the AEM conductors. In addition the AEM anomalies were classified on the basis of this reconnaissance work into a list of priority targets for use in economic studies, and six AEM anomalies were selected for further studies. During Phase 2 conducted in the 1979 field season, ground geophysical work consisting of electromagnetic (EM), self-potential (SP), and selected magnetic surveys were carried out in the six targets selected in the Phase 1 studies. These target areas in aggregate cover about 30 km 2, and are approximately half of the Wadi Bidah Class 1 and Class 2 priority targets found during the 1977 airborne electromagnetic (AEM) survey of parts of the Arabian Shield. The results indicate possible extension of known reserves at the Rabathan area (AEM anomaly B-29), with possible potential for mineralization in the area extending 15-20 km north (anomaly B-13), where the geologic and geophysical environment is similar. An important observation is that mineralization in the B-29 (Rabathan) zone is coincident with narrow SP anomalies superimposed on the larger, broader, and more formational-type SP anomalies encountered in both areas B-29 and B-13. AEM anomaly B-25-26 areahas geophysical characteristics that show in the groundwork and that make it an attractive drill target. EM and SP anomalies are associated, in part, with magnetic anomalies and with exposures of significant limonitic gossan. Wadi al Khadra prospect, not included in the 1977 AEM survey, and the AEM anomaly B-25-26 area were also high-mineralization-potential products of the Phase 2 studies. Target area B-35 remains an unknown quantity, and AEM anomaly B-24 is almost certainly due to a carbonaceous schist. Geochemical results, along with detailed geologic mapping and the geophysical data, indicate several potential mineralized targets. Further detailed geophysics (EM and SP) will assist in understanding the geophysical data thus far collected. Further ground follow-up studies are recommended.

Open-File Report↗
USGS1983

Preliminary report on near-surface lignite occurrences, Cleveland County, Arkansas

Four cross sections were constructed from lithologic descriptions of 43 drill holes in Cleveland County, Ark., in order to illustrate the occurrence of lignite and to relate the lignite beds to the regional stratigraphic framework. Of 43 holes drilled, 8 contained beds of lignite, but only two had beds greater than 30 in. thick. These beds are apparently lenticular and are restricted to the upper 60 ft. of the Cockfield Formation of the Claiborne Group of Middle Eocene age. The Cockfield Formation is at or near the surface west of the Saline River.

Open-File Report↗
USGS1984

Evaluation of the ground-water resources of coastal Georgia; preliminary report on the data available as of July 1983

A compilation of ground-water data that have been collected for nearly 100 years in the coastal area of Georgia as part of cooperative activities between the U.S. Geological Survey and other agencies is presented in this report. The compilation of pertinent data indicates that information is available for use in the evaluation of the ground-water resources of the 13 counties of coastal Georgia. Included in this report is a fairly complete discussion of previous and ongoing investigations and monitoring networks, and an extensive list of references. Maps at 1:24,000, 1:100,000; and 1:1000,000 scales contain well locations and identifers for all wells in the Ground Water Site Inventory (GWSI) data base of the National Water Data Storage and Retrieval System (WATSTORE). Tabular summaries of selected site information from GWSI, including well identifiers and names , latitude-longitude location, depth of well, altitude of land surface, and use of water are presented. Water-use data from the National Water Use Data System, and water use for irrigation from the University of Georgia, Department of Agriculture survey , are tabulated. Also included are pertinent information on geophysical surveys and data obtained, and proposed project activities, particularly test-monitor well drilling.

Georgia↗
USGS1985

Preliminary report on a study to estimate flood volumes of small rural streams in Ohio: Methods, site selection, and data base

In 1981, the U.S. Geological Survey, in cooperation with the Ohio Department of Transportation and the Federal Highway Administration, began a 7-year flood-volume study of small rural basins in Ohio. This report summarizes the methods of study and describes reconnaissance and site-selection procedures, locations and characteristics of the stations, instrumentation, and methods of collecting and storing data. The first phase of this study involved an intensive field reconnaissance of about 7,000 sites, of which 32 basins were selected for detailed analysis. Drainage areas for the basins varied from 0.13 to 6.45 square miles, and main-channel slopes ranged from 7.6 to 276 feet per mile. Five years of 5-minute rainfall-runoff data will be colledted for each study site. These data will be used to calibrate and verify a rainfall-runoff model for each basin. The calibrated model will be used in conjunction with 80 years of National Weather Service 5-minute precipitation data to synthesize a representative 80-year streamflow record at each site. A Log-Pearson Type III frequency distribution will be applied to each record to define the magnitudes and frequencies of flood volumes at each site. These data will be used to develop regionalized multiple regression models for estimating flood-volume magnitudes and frequencies at small rural ungaged sites in Ohio. The report also summarizes rainfall-runoff data collected from July 1981 through September 1983, but does not interpret the data. An average of eleven event periods per site were monitored where maximum 5-minute rainfall intensities varied from 0.02 to .067 inches and maximum peak discharges varied from 1 to 1,130 cubic feet per second.

Ohio↗