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Research about South Dakota

Source-linked reports with geographic coverage including South Dakota.

At least 451 records · Page 25Linked to original sources
USGS1955

Geology of the Fourmile pegmatite area, Custer County, South Dakota

The Fournile pegmatite area covers 32 sq. mi. in the western part of the Custer pegmatite mining district, Custer County, South Dakota. This area has been one of the major sources of sheet mica in the United States, especially between 1906 and 1911, and it has been a significant source of potash-feldspar, beryl and spodumene. The area is part of the much larger area of pegmatites and metamorphic rocks to the north and east that surround Harney Peak and extend throughout the southern part of the pre-Cambrian core of the Black Hills. Paleozoic rocks underlie the western part of the Fourmile area.

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USGS1955

Geology and beryl deposits of the Peerless pegmatite, Pennington County, South Dakota

The Peerless pegmatite, half a mile south of Keystone, Pennington County, S. Dak., has been a large source of scrap mica and beryl. Feldspar, amblygonite, tantalite-columbite, and cassiterite also have been recovered. The pegmatite is intrusive into Precambrian quartz-mica schist. Much of the schist contains staurolite and chlorite. Staurolite has been partly altered to mica, quartz, and chlorite, especially near pegmatite contacts. The pegmatite is generally discordant with the schist, but in many places secondary schistosity has been developed parallel to the contact. Tourmaline and muscovite, presumably introduced by pegmatitic solutions, are characteristic of the wall rock near discordant contacts. At the surface the pegmatite is tadpole-shaped and is 580 feet long and 360 feet wide. In cross-section the pegmatite has an anticlinal form that suggests control of the intrusion by fractures bearing N. 30°W. and dipping 45°NE. and SW. Dike-like apophyses extending from the main pegmatite have various attitudes. The Peerless pegmatite is a complex pegmatite consisting of seven zones, two replacement units, and two types of fracture-fillings. These are: Zone 1, quartz-muscovite-plagioclase pegmatite (border zone); Zone 2, albite-quartz-muscovite pegmatite (wall zone); Zone 3, cleavelandite-quartz-muscovite pegmatite (first intermediate zone); Zone 4, perthite-cleavelandite-quartz pegmatite (second intermediate zone); Zone 5, clevelandite-quartz pegmatite (third intermediate zone); Zones 6a and b, quartz-microcline pegmatite and quartz pegmatite (fourth intermediate zone); Zone 7, lithia mica-cleavelandite pegmatite (core); lithia mica-cleavelandite-quartz replacement unit; muscovite-cleavelandite replacement unit; quartz fracture-fillings; and tourmaline-quartz fracture-fillings. Zones 1 and 2 consist of alternating layers of different texture and mineralogy that are parallel to the contact. The layers contain differing proportions of quartz, plagioclase, muscovite, perthite, and accessory minerals. Sugary albite-quartz aggregates are important constituents of some layers. Layers of similar composition may occur two, three, or perhaps more times. The overall mineralogic composition of Zones 1 and 2 is similar to the composition of wall zones in many other Black Hills pegmatite, Zones 3 to 7 are in the normal sequence of zones in Black Hills pegmatites. The structural, textural, and mineralogic data confirm previously published evidence from other Black Hills pegmatites that indicates crystallization of a magma-like fluid from the wall inward. Repetition of layers in Zones 1 and 2 indicates changes in composition of the fluid at the crystallizing face. These changes may have been caused by addition of new material from below, by loss of material to the wall rocks, or by failure of convection to maintain equilibrium throughout the fluid in the pegmatite chamber. Zone 3 to 7 are in the normal sequence of zoned pegmatites that indicates crystallization from a restricted or nearly closed system. The lithia mica-cleavelandite replacement unit, which extends outward from the core, shows that in, the very late stages of crystallization a pneumatolytic or hydrothermal fluid escaped outward and replaced previously crystallized pegmatite. Accessory minerals of the pegmatite include tourmaline, beryl, apatite, amblygonite (variety, montebrasite), lithia mica, cassiterite, tantalite-columbite, garnet, spodumene, svanbergite, loellingite (?), vivianite (?), triploidite (?), dahllite, and vari-colored phosphate minerals of the lithiophilitetriphylite group and their alteration products. The chemical composition of the pegmatite has been determined by estimating the mineral, constitution of the various units and by calculating the tonnage of these units by use of successive geologic sections. The principal constituents are: SiO 2 (77.0 percent), Al 2 O 3 (13.7 percent), Na 2 O (5.0 percent), and K 2 O (1.7 percent). Chemical composition has also been determined for four subdivisions of the pegmatite: (A) Zones 1 and 2, (B) Zones 3 and 4, (C) Zone 5, and (D) Zones 6 and 7 and the replacement units. The content of Si0 2 increases and the content of Al 2 O 3 decreases from the outer pan of the pegmatite inward. Na 2 O forms only 0.4 percent of the inner subdivision (D), but 4 .7 to 6.5 percent of the other subdivisions. K 2 O forms 4.0 percent of subdivision (B), but only 0.7 to 1.3 percent of the other subdivisions. Zone 3, the principal minable unit, contains 1. 7 percent beryl and 28 percent scrap mica. Beryl also constitutes more than 1 percent of parts of the wall zone, especially albite-rich layers of the inner part of the unit in the upper part of the pegmatite. Beryl is a less important constituent of other units of the pegmatite. Potash feldspar is mined chiefly from Zone 4. Clevelandite that can be hand-cobbed and sold as soda-feldspar occurs in Zones 3, 4, and 5. Amblygomlte forms between 0.5 and 1.0 percent of Zone 5. Reserves of beryl, scrap mica, potash feldspar, and amblygonite are one to six times past production.

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USGS1955

Reconnaissance of geology and ground water in the lower Grand River valley, South Dakota, with a section on Chemical quality of the ground water

The area described in this report is the flood plain of the Grand River and the bordering benchlands in Perkins and Corson Counties, S. Dak., from a point about 6 miles west of the town of Shadehill to the confluence of the Grand and Missouri Rivers near Mobridge. The exposed bedrock formations include the Pierre shale, the Fox Hills sandstone, and the Hell Creek formation of Late Cretaceous age, and-the Ludlow member of the Fort Union formation of Tertiary (Paleocene) age. Some stringers of the Cannonball formation probably interfinger with beds of the Ludlow member but none of the former was identified during the field investigations. The Pierre shale is exposed from the mouth of the Grand River to approximately the center of the area. Although a few wells in the area obtain water from this formation, it is not generally considered to be a source of supply. The Fox Hills sandstone, the Hell Creek formation, and the Ludlow member of the Fort Union formation are exposed successively upstream and, where saturated, yield small to moderate quantities of water to wells. Unconsolidated deposits of silt, sand, and gravel occur in several physiographic positions; they underlie the high benchland on both sides of the river, the poorly defined terraces along the river, and the flood plain throughout its entire length. Possibly all these unconsolidated deposits are water bearing; however, where the deposits on the benchland and in the terraces are dissected by streams, they probably contain little or no water. The average depth to ground water along the lower Grand River valley is about 17 feet. Probably, the flow of ground water in the bottom lands is nearly parallel to and slightly toward the surface stream. The measurements of the water level in observation wells for the period 1946-48 indicate that the fluctuations of the water table are small. The results of analyses of 13 samples of ground water from the alluvium and the Hell Creek formation show that the suitability of the ground water for use varies because of the considerable range in mineralization and composition. Dissolved solids ranged from 343 to 4,250 parts per million (ppm), hardness from 11 to 1,130 ppm, and percentage of sodium from 25 to 98. Concentrations of some of the individual constituents exceed standards of the United States Public Health Service. The water is moderately hard and contains undesirable amounts of iron and moderate to large amounts of dissolved solids. In general, the water quality ranges from excellent to unsuitable for irrigation use. The result of the mixing of the ground water with recharge water from Shadehill Reservoir cannot be predicted on the basis of available data. The geologic and hydrologic data in this report were obtained from earlier reports and from field observations during the period 1946-48. The report includes a geologic map and tabulated well records.

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USGS1954

Geology of the Eureka pegmatite, Pennington County, South Dakota

The Eureka Pegmatite, two miles southeast of Keystone, Pennington County, South Dakota, is a small but possibly valuable zoned body containing more than 85,000 tons of coarse-grained granite-pegmatite rock. The mica in the pegmatite is probably not of any great importance, but the potash feldspar and beryl may comprise a considerable tonnage of valuable reserves. If the pegmatite can be exploited at a profit in spite of the graphite-damaged feldspar, it may yield substantial amounts of strategically important beryl by open-cut mining of the entire body. This report contains complete, megascopic mineralogical and structural details of the pegmatite, which are supplemented with drill core logs and a geologic map and cross-sections.

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USGS1954

Uranium deposits in Fall River County, South Dakota

In 1951 uranium deposits contained carnotite were discovered in the southern Black Hills near Edgemont, Fall River County, S. Dak. Numerous carnotite deposits have since been found in sandstones in the Inyan Kara group of early Cretaceous age, and uranium-bearing material has been discovered in the Pennsylvania Minnelusa sandstone of Pennsylvanian age and the Deadwood formation of Cambrian age in the southern Black Hills. Ore has been produced only from the Inyan Kara group, mostly within an area of about 30 square miles along the southwest flank of the Black Hills uplift between Dewey and Hot Springs in Custer and Fall River Counties. In addition, occurrences of uranium in other parts of the Black Hills and the surrounding area are known or reported from sedimentary, igneous, and metamorphic rocks of pre-Cambrian to Tertiary age. The upper and lowermost formations of the Inyan Kara group - the Fall River and Lakota sandstones - contain the productive uranium deposits. These terrestrial formations are composed predominantly of massive sandstone lenses within units of thinly bedded sandstone and mudstone, but locally these formations contain abundant mudstone and thinly bedded sandstone. Massive sandstone lenses in the Lakota sandstone commonly overlap and truncate underlying lenses. The lenses are separated by thin units of thinly bedded sandstone and mudstone. Iron stain, carbonaceous material, thin seams of gypsum, ripple marks, concretions, and fossil roots are common in the mudstone and thinly bedded portions of these formations. Some high angle normal faults of small displacement are found in the area containing the largest number of uranium occurrences in the Inyan Kara group. Although no ore deposits seen were cut by faults, high-angle fractures parallel and at right angles to the faults contain carnotite for short distances. The productive uranium deposits are most common where the Fall River and Lakota sandstones locally contain a large proportion of mudstone and thinly bedded sandstone. Other deposits are in the massive sandstone lenses of the Lakota sandstone and in the thin units between the lenses. Although carnotite is the most conspicuous and important mineral in most deposits, corvusite is an important constituent of some deposits. Other uranium minerals in the deposits are tyuyamunite, rauvite, and autunite. Ore produced in 1952 from the Fall River and Lakota sandstones contained about 0.2 percent U 3 O 8 and 0.6 percent V 2 O 5 . In general, deposits in the Fall River and Lakota sandstones contain about the same percentage of U 3 O 8 , but the deposits in the Fall River sandstone appear to have a higher percentage of vanadium. The grade of individual deposits, however, is highly variable. Most deposits are small, but a few have yielded as much as a thousand tons of ore.

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USGS1954

Carnotite-bearing sandstone in Cedar Canyon, Slim Buttes, Harding County, South Dakota

Carnotite-bearing sandstone and clay have been found in the Chadron formation of the White River group of Oligocene age in the southern part of the Slim Buttes area, Harding County, S. Dak. Locally the mineralized sandstone contains as much as 0.23 percent uranium. The uranium and vanadium ions are believed to have been derived from the overlying mildly radioactive tuffaceous rocks of the Arikaree formation of Miocene age. Analyses of water from 26 springs issuing from the Chadron and Arikaree formations along the margins of Slim Buttes show uranium contents of as much as 200 parts per billion. Meteoric water percolating through tuffaceous rocks is thought to have brought uranium and other ions into environments in the Chadron formation that were physically and chemically favorable for the deposition of carnotite.

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USGS1954

The stratigraphic and structural controls of the uranium deposits on Long Mountain, Fall River County, South Dakota

Numerous occurrences of uranium have been found in the Long Mountain area, Fall River County, S. Dak. Correlation diagrams prepared from drill, cores obtained from the U.S. Atomic Energy Commission indicate that the uranium is most abundant in two sandstone units, separated by mudstone in the Lakota sandstone of Early Cretaceous age. The lower uraniferous unit is composed of thick beds of very fine- to fine-grained sandstone with a few interfingering lentils of mudstone. The upper uraniferous unit is composed of interfingering beds of very fine-, fine-, and coarse-grained sandstone and mudstone. The uranium deposits on Long Mountain and in the area to the west are most numerous in a northeast-trending zone about a mile wide between two normal faults. The deposits between these faults are in two groups of different trend; the northern group has been incompletely explored. The sedimentary structures of the upper and lower mineralized sandstone between the faults have controlled the deposition of uranium and vanadium.

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USGS1954

Results of core drilling for uranium-bearing lignite, Mendenhall area, Harding County, South Dakota

Core drilling for data on uranium-bearing lignite in the Mendenhall area, Harding County, S. Dak. , was conducted by the U. S. Bureau of Mines during the period October 1952 to July 1953. Forty-two core holes totaling 9, 683 feet drilled in an area of about six square miles indicate a reserve of about 127/000,000 tons of lignite of which about 49,000,000 tons contain an average of 0.005 percent uranium or more. The Mendenhall area is near the center of the Slim Buttes, which are about 30 miles long from north to south. The uranium-bearing lignite averages, 5. 4 feet in thickness and occurs in the Ludlow member of the Fort Union formation of Paleocene age. Fuel analyses of about 130 samples indicate that the lignite contains about 15 percent ash, 36.7 percent moisture, 24r percent fixed carbon, 23.9 percent volatile matter, and 1.5 percent sulfur and has heating values of about 5,800 btu (as received). Uranium analyses of about 700 samples of lignite core indicate that about 2, 790 tons of uranium are present in the Mendenhall area. Inferred uranium reserves of 2,335 and .1. 050 tons are indicated by grade cutoffs of 0. 005 and 0. 01 percent uranium in the lignites, and 2, 065 and l s 35Stons are indicated by grade cutoffs of 0.03 and 0.05 percent uranium in the lignite ash. The above grade cutoffs have been incorporated on maps showing areal distribution: and thickness of mineralized beds.

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USGS1953

Ground-water resources of the Rapid Valley unit, Cheyenne Division, South Dakota, with a section on the surface waters of Rapid Valley

The Rapid Valley unit is in Pennington County, S. Dak., and extends from the east city limits of Rapid City southeastward for 21 miles along Rapid Creek. The bedrock formations that underlie the region are chiefly marine in origin, and they generally dip eastward from the center of the Black Hills uplift. The exposed formations are of Cretaceous age and consist of the Greenhorn limestone, the Carlile shale, the Niobrara formation, and the Pierre shale. The Pierre shale, which underlies the unconsolidated flood plain and terrace deposits in much Of the region is exposed in the erosional slopes along the south side of the valley and in the deeper draws on the north side. The areas in which the other formations are exposed are relatively small and are restricted to the western part of-the region. Four terraces are present on the north side of Rapid Creek. The lowest terrace and the flood plain in the western half of the region are irrigated at the present time, and the two lower terraces and the flood plain in the eastern half have been proposed for irrigation. Abundant supplies of ground water occur in the flood plain and terrace deposits where they are now irrigated. Because the waterbearing materials consist of interfingering layers of differing permeability, the ground water is under water-table conditions in some places whereas it is confined in others. Locally, where there is a confining layer below other water-bearing materials or where a confined layer is itself saturated, the ground water may occur under both water-table and artesian conditions. Seepage from irrigation canals, which is the principal source of recharge, causes high ground-water levels from June to November; as a result, parts of the areas have become waterlogged. In the parts of the region that are not now affected by irrigation, the surface of the ground water is only a few feet above the bedrock surface and 6 ft to 42 ft below land surface; its position is relatively constant throughout the year. Harmful concentrations of salt in the soil are in part due to evaporation of ground water. These are found only locally in the Rapid Valley region and do not present a serious problem at this time. It is thought, however, that the fine-grained materials underlying the Rapid terrace may contain sufficient salt to cause detrimental salt accumulations in the soil if the proposed irrigation causes ground-water levels to rise close to the surface. Lining of the irrigation canals would reduce the amount of seepage and would effect a lowering of ground-water levels, if irrigation practices are extended to other areas, drainage facilities will be necessary both to avoid aggravating the existing conditions of waterlogging and to prevent the waterlogging of other low-lying lands. The flow of Rapid Creek is affected by a variety of conditions. A few miles west of Rapid City, where Rapid Creek flows over the Englewood and Pahasapa limestones and the Minnelusa sandstone, there is a loss of about 8 cfs of water in a distance of a few miles. In the 3-mile reach of Rapid Creek between the Canyon Lake stream-gaging station and the Rapid City stream-gaging station there is a gain of about 20 cfs; much of this gain in flow may be attributed to the inflow from Cleghorn and Jackson springs and to the addition of water from the State-owned cement plant. In the Rapid Valley unit, the flow of the creek during the irrigation season is affected largely by the amount of water diverted for irrigation. The irrigation canals act as bypass channels, much of the water being returned to Rapid Creek by way of spillage into normally dry tributary creek channels and by movement through ground-water bodies that discharge into Rapid Creek.

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USGS1953

Chemical quality of water and sedimentation in the Moreau River drainage basin, South Dakota

This report gives the results of an investigation by the U. S. Geological Survey of the sediments and dissolved minerals that are transported by the Moreau River. The Moreau River drainage basin is a narrow basin in northwestern South Dakota that covers about 5, 360 square miles of rolling, grassy plains, which are broken by buttes and by some small areas of badlands. It is underlain by shales, sandstones, siltstones, and limestones that are primarily of Cretaceous age. Precipitation averages about 16 inches per year. Average annual runoff is about 0. 7 inch but varies widely from year to year.

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