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At least 343 records · Page 19Linked to original sources
USGS1976

Preliminary report on uranium-, thorium-, and rare-earth-bearing rocks near Golovin, Alaska

Uranium-, thorium-, and rare-earth bearing rocks were found by a U.S. Geological Survey field party 15 miles northeast of Golovin, Alaska, in the southeastern Seward Peninsula (fig. 1) in June 1976. The mineralized areas occur in syenite and appear to be concentrated along the margins of alkaline dikes, with allanite tentatively identified as the principal mineral containing the uranium-, thorium-, and rare-earths. Samples contain as much as 0.15 percent U 3 0 8 and 1.05 percent Th0 2 , and over 2 percent rare-earth elements. These mineralized rocks are closely associated with alkaline dikes which are part of a dike swarm that crops out over at least 250 km 2 (100 mi 2 ). This large dike swarm is thus of considerable economic interest. These uranium-, thorium-, and rare-earth-rich rocks occur near the west end of the western Alaska uranium-thorium province (West, 1953; Clark and others, 1975; Miller, 3976) and were found during a regional investigation of this province by the Geological Survey. The alkaline dikes were known from previous mapping by the two senior authors (Miller and others, 1972) to be anomalously radioactive. The mineralized areas described in this report were found while making a brief study of (1) alteration and/or mineralization associated with these dikes and (2) their relation to similar dikes and rocks which occur elsewhere in the province (Miller, 1972).

Alaska↗
USGS1977

Interpretation of Landsat images: Qatar (preliminary report)

The Emirate of Qatar is shown on this mosaic of two Landsat images. Before mosaicking, false-color composites of each of the two images were printed on Cibachrome material. Some of the surficial and bedrock units, as well as some cultural features, are easily detected on land.

Open-File Report↗
USGS1977

Interpretation of Landsat images: Kuwait (preliminary report)

Two Landsat Images, 1153-06514 and 1153-06521, show all of Kuwait except the extreme western part. They were taken on December 23, 1972, only two days after the winter solstice. Sun elevation at that time is 30° which approaches the minimum value for Kuwait's latitude, a condition that enhances shadows and maximizes contrasts in a land of low relief and high desert reflectance. False-color composites of both images have been printed on Cibachrome material.

Open-File Report↗
USGS1977

Preliminary report on the lignite resources of the Niobe area, Burke and Ward counties, North Dakota

Two lignite beds, the Niobe and the Bonus, occur at strippable depths within the Niobe area. The Niobe bed averages 5 feet (1.5 meters) in thickness and the Bonus bed averages 8 feet (2.4 meters) in thickness. These beds lie in the lower part of the Sentinel Butte Member of the Fort Union Formation (Paleocene). The demonstrated resources of both beds combined is 122 million tons (110 million tonnes), all of which are under less than 120 feet (37 meters) of overburden. The overburden consists of glacial till and shale. The lateral continuity of the coal has been locally interrupted by faulting, glacial outwash channels, and erosion. Folding and/or faulting occurs parallel to the Missouri Coteau escarpment and faulting occurs roughly perpendicular to the escarpment.

Open-File Report↗
USGS1977

Preliminary report on the coal resources of the Dickinson area, Billings, Dunn, and Stark Counties, North Dakota

The Dickinson area is underlain by the coal-bearing Fort Union Formation (Paleocene). The Fort Union in this area contains nine potentially economic coal beds. Five of these beds are, either all or in part, shallow enough to be economically extracted by conventional strip-mining methods, while the remaining four deeper beds represent future possible strip-mining, in situ, or shaft-mining coal resources. The Fort Union coal beds in the Dickinson area are relatively flat lying (dips are less than 1½°) and only slightly influenced by faulting and both depositional and post-depositional channeling. Topography, coal thickness, and minimum overburden all combine to give the Dickinson area an excellent future coal resource development potential.

North Dakota↗
USGS1977

Uranium and thorium in the middle Precambrian Estes Conglomerate, Nemo District, Lawrence County, South Dakota: a preliminary report

The Estes Conglomerate, which is exposed in the Nemo District on the northeastern flank of the Black Hills, South Dakota, is inferred to be of early middle Precambrian age (early Precambrian X or Paleoaphebian) and to be resting on late early Precambrian (late Precambrian W) granitic continental crust. The Estes contains beds of quartzite and quartz-pebble conglomerate (oligomictic conglomerate) with matrices of micaceous quartzite that locally contain 5 to 25 percent dispersed pyrite. Highly oxidized outcrop samples of the oligomictic conglomerate have anomalously high contents of both uranium (10 to 40 ppm) and thorium (20 to 800 ppm). High thorium values in the oligomictic conglomerate favor a placer mechanism for the concentration of radioactive minerals and appear to eliminate the possibility of epigenetic processes, such as reduction of uranium by pyrite. The presence of abundant old prospect pits and of several abandoned mines suggests that these conglomerates may also contain some gold. Early prospectors may have been attracted by the gossan produced by oxidation of pyrite. Uranium in the Estes Conglomerate may be of similar origin to the economically very important uranium deposits in the Matinenda Formation of the Elliot Lake District, Ontario. Because uranium is rapidly dissolved in acidic, oxygenated ground water, such as is present where pyrite is weathering, most of the uranium originally present in the analyzed samples has probably been leached out. Conglomerate located below the zone of weathering and oxidation has good potential for economic uranium deposits.

Open-File Report↗
USGS1977

Mineralogical, chemical, and physical properties of the regolith overlying crystalline rocks, Fairfax County, Virginia: a preliminary report

Undisturbed cores of saprolite developed on crystalline rocks of the Piedmont Province in Fairfax County, Virginia have been obtained using a combination of Shelby tubes, Denison sampler, and modified diamond core-drilling. The principal purpose of the core study is to correlate variations in chemistry, mineralogy and texture with engineering properties throughout the weathering profile. Coring sites were chosen to obtain a maximum depth of weathering on diverse lithologies. The rocks investigated include pelitic schist, metagraywacke, granite, diabase and serpentinite. Four to twelve samples per core were selected, depending on thickness of 1) the weathering profile (from about 1 m in serpentinite to more than 30 m in pelitic schist) and on 2) megascopic changes in saprolite character for analysis of petrography, texture, clay mineralogy andd major element chemistry. Shear strength and compressibility were determined on corresponding segments of core. Standard penetration tests were performed adjacent to coring sites to evaluate engineering properties in situ. Geochemical changes of saprolite developed from each rock type follow predictable trends from fresh rock to soil profile, with relative Increases in Si, Ti, Al, Fe3+ and H20; variable K; and relative loss of Fe 2+, Mg, Ca, and Na. These variations are more pronounced in the weathering profiles over mafic and ultramafic rocks than metagraywacke. Clay minerals in granite, schist and metagraywacke saprolite are kaolinite, dioctahedral vermiculite, interlayered micavermiculite, and minor illite. Gibbsite is locally developed in near-surface samples of schist. Standard penetration test data for the upper 7 m of saprolite over schist and metagraywacke suggest alternations between stronger and weaker horizons than probably reflect variations in lithology including the presence of quartz lenses. Results for granite saprolite are most consistent but indicate lower strength. Shear strength increases fairly regularly downward in the weathering profile. The engineering behavior of diabase saprolite is controlled by a dense, plastic, near-surface clay layer (montmorillonite and kaolinite)overlying rock which is weathered to a granular state (grus), while engineering properties of serpentinite are determined by a very thin weathering profile.

Open-File Report↗