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At least 649 records · Page 36Linked to original sources
USGS1977

Enthalpies of formation of low albite (NaAlSi 3 O 8 ), gibbsite (Al(OH) 3 ), and NaAlO 2 ; revised values for Δ H ° f,298 and Δ G ° f,298 of some aluminosilicate minerals

The enthalpies of formation from the elements Δ H ° t , of low albite, analbite, NaAlSi 3 O 8 glass, gibbsite (Al(OH) 3 ), and NaAlO 2 , have been determined by hydrofluoric acid solution calorimetry from measurements of the heats of solution, Δ H ° soln , of low albite, NaAlO 2 , SiO 2 , Al(OH) 3 , Al, H 2 O, NaCl, and HC1-12.731H 2 O in 20.1 weight percent HF(aq) at temperatures between 303.15 and 348.15 K. At 298.15 K the enthalpies of formation, Δ H ° f,298 , for low albite, analbite, NaAlSi 3 O 8 glass, gibbsite ( Al(OH) 3 ), and NaAlO 2 are -3 935 115±3415, -3 924 235±3640, -3 875 455±3700, ±1293130±1190, and 1135 990±1255 J mol -1 , respectively. Our values for the enthalpies of formation of low albite, analbite, and for NaAlSi 3 O 8 glass are approximately 13 810 J mol -1 more negative than the values calculated by D. R. Waldbaum in 1968. Our value for the enthalpy of formation of gibbsite at 298.15 K is 11234 J more negative than the value of R. Barany and K. K. Kelley obtained in 1961. The standard Gibbs free energies of formation, Δ G ° f,298 for low albite, analbite, and gibbsite calculated from the above enthalpies and the appropriate entropy data are -3 711 715±3435, -3 706 500±3660, and -1154 890±1200 J mol -1 , respectively. The enthalpy of solution of Standard Reference Material 1654, α-quartz (37 to 74 μm), in 20.1 wt percent HF(aq) is -137 737±209 J mol -1 at 333.15 K. This value is approximately 1255 J less negative than the value obtained by King in 1951 and 1952 for material that has a mean particle diameter of less than 5 μm and that has been used by the U.S. Bureau of Mines in their determinations of the enthalpies of formation of many silicates. Revised values of the enthalpies and Gibbs free energies of formation are presented for some aluminosilicate minerals, based upon this new data for Δ H ° f,298 of gibbsite and the heat of solution of α-quartz.

Journal of Research of the U.S. Geological Survey↗
USGS1977

Chemical dissolution of sulfide minerals

Chemical dissolution treatments involving the use of aqua regia, 4 N HNO 3 , H 2 O 2 -ascorbic acid, oxalic acid, KClO 3 +HCl, and KClO 3 +HCl followed by 4 N HNO 3 were applied to specimens of nine common sulfide minerals (galena, chalcopyrite, cinnabar, molybdenite, orpiment, pyrite, stibnite, sphalerite, and tetrahedrite) mixed individually with a clay loam soil. The resultant decrease in the total sulfur content of the mixture, as determined by using the Leco induction furnace, was used to evaluate the effectiveness of each chemical treatment. A combination of KClO 3 +HCl followed by 4 N HNO 3 boiling gently for 20 min has been shown to be very effective in dissolving all the sulfide minerals. This treatment is recommended to dissolve metals residing in sulfide minerals admixed with secondary weathering products, as one step in a fractionation scheme whereby metals in soluble and adsorbed forms, and those associated with organic materials and secondary oxides, are first removed by other chemical extractants.

Journal of Research of the U.S. Geological Survey↗
USGS1977

Microwave radiometric survey of the San Joaquin nuclear project site, Kern County, California

An airborne microwave survey was made in the region of the San Joaquin nuclear project site near Bakersfield, Calif. The purpose of the study was to determine if the variability of soil emissivity due to moisture content is a valid near-surface expression of buried fault systems. The results showed the existence of linear-emissivity anomalies paralleling, and to some extent, overlying the Greeley and Pond-Poso Creek faults. The anomalies seem to be direct expressions of silt-filled, northwesterly trending channels of the Pond-Poso Creek-Tulare Lake distributary system. The location, orientation, and linearity of the distributary channels suggest an association with buried faults, but no relationship has yet been determined.

California↗
USGS1977

Magnitude, distance, and intensity data for C.I.T. strong motion records

The site Modified Mercalli intensities and epicentral distances of strong motion records published by the California Institute of Technology are reported, as well as the magnitude, focal depth, and maximum Modified Mercalli intensity of the event associated with each record. These data were obtained from original sources. The use of the data to derive ground motion relations for design is discussed; possible biases in the data which might affect such relations are described.

Journal of Research of the U.S. Geological Survey↗
USGS1977

Spherulitic rhyolite dike from Goat Island, southeastern Alaska

Spherulites, as much as 4 mm in diameter, locally constitute almost 50 percent by volume of a dark-red rhyolite dike that intrudes porphyritic pyroxene gabbro along the northeast coast of Goat Island, 3.2 km northwest of Hydaburg, southeastern Alaska. The largest spherulites are composed mainly of o-quartz, whereas the smallest consist of a microcrystalline intergrowth of tridymite and alkali feldspar. Textural relations indicate that the radial and concentrically zoned structures are the products.of devitrification of glassy lava. The mineralogy of the dike is similar to that of other spherulitic rhyolites except that quartz occurs to the exclusion of cristobalite. The posteruptive formation of the spherulites has also resulted in alkali transfer, the groundmass of the dike being enriched in both sodium and potassium relative to the spherulites.

Alaska↗
USGS1977

A new curved baculite from the Upper Cretaceous of Wyoming

Baculites reduncus , n. sp., is a moderately large ammonite that has a curved shell, a large angle of taper, and a stout ovate cross section. Conspicuous broad, arcuate ribs cross the upper two-thirds of the flank. The suture, which is fairly complex, has a distinctive lateral lobe. All the types are from the lower part of the Rock River Formation near Rock River, Wyo. The species is of late Campanian age and marks a zone between the Zones of Baculites gregoryensis Cobban and B. scotti Cobban

Wyoming, Colorado↗
USGS1977

Miospore diversity and its relationship to lithology in the Coker Formation (Upper Cretaceous) of western Alabama

A multiple-regression procedure was applied to samples from two cores of the Coker Formation (Upper Cretaceous) of western Alabama in an attempt to characterize the relationship between the diversity of miospore species and selected lithologic factors. The resulting prediction equations suggest that the number of miospore species in these samples is inversely related to changes in median grain size and to other as yet undefined factors not reflected by lithology. In addition, it appears that the degree of sorting of the sediment has no effect on species diversity. A plot of these prediction equations shows that changes in the number of miospore species are negligible in samples of clay and silt size but that the number of species decreases rapidly in sediments of fine sand size or coarser. The results presented here agree with those presented by other workers for the relationship between grain size and the absolute abundance of miospores.

Alabama↗
USGS1977

Hydrologic characteristics of the Madison Limestone, the Minnelusa Formation, and equivalent rocks as determined by well-logging formation evaluation, Wyoming, Montana, South Dakota, and North Dakota

Geophysical logs from wells distributed throughout the Powder River Basin were digitized, processed, and interpreted to get a regional understanding of the lithologic and ground-water characteristics of aquifers in the Madison Limestone and Minnelusa Formation. The percentage of sand, porosity, and apparent ground-water resistivity of the Minnelusa closely follow structural trends in the basin. Values increase from the structural axis of the basin toward the flanks. Close correlations between the water resistivities in the Madison and the Minnelusa indicate possible hydrologic connection between the two units. The low primary porosity from geophysical logs in the Madison indicates that secondary porosity is necessary to develop water supplies of economic importance from the Madison. Because of increased porosity and better water quality, the flanks of the basin appear to be the most favorable places for water production from either the Madison or the Minnelusa.

Wyoming, Montana, South Dakota, North Dakota↗
USGS1977

Relation of surflcial erosion on hillslopes to profile geometry

Differences in erosion rates in relation to the geometry of hillslope profiles were hypothesized by R. E. Horton in 1945. Experimental testing of this hypothesis is described for natural hillslopes in western Colorado using a rainfall simulator to apply five "storms" each having an intensity of 1.85 inches per hour (47 millimeters per hour). Erosion from straight hillslope segments was about twice the amount from convex and concave segments along nine hillslope transects. Standard deviations of erosion measurements for each segment show that the greatest variation occurs in concave slope segments. This is probably because the concave segment is the only place on the profile where deposition occurs. Analysis of variance indicates that the amount of erosion is significant at the 1-percent level of confidence between convex and straight slope segments and at the 5-percent level of confidence between straight and convex slope segments.

Colorado↗
USGS1977

A Galerkin, finite-element analysis of steady-state flow and heat transport in the shallow hydrothermal system in the East Mesa area, Imperial Valley, California

A steady-state simulation model was applied to the shallow hydrothermal system in the East Mesa area of Imperial Valley, Calif. The steady-state equations of flow and heat transport were solved by use of a Galerkin, finite-element method. A solution was obtained by iterating between the temperature and pressure equations, using updated densities and viscosities. Temperature and pressure were obtained for each node, and corresponding head values were calculated. The simulated temperature and pressure patterns correlated well with the observed patterns. Additional data, mainly from test drilling, would be required for construction of a similar model of the deep hydrothermal system.

California↗
USGS1977

Solubility of natural fluorite at 25°C

The solubility products of two samples of natural fluorite from Rosiclare, Ill., and from Madoc, Ontario, were determined at 25°C by analyses of calcium and fluoride in sodium perchlorate solutions of varying ionic strength over a period of 3 years. Calcium concentrations were analyzed by atomic absorption spectrophotometry, fluoride concentrations were measured colorimetrically, and fluoride activities were measured using a specific ion electrode. The solubility products at the end of 3 years were determined by extrapolation to zero ionic strength. The final solubility product was found to be 10 -10.58±0.17 .

Journal of Research of the U.S. Geological Survey↗
USGS1977

Benthic invertebrates in an arctic mountain stream, Brooks Range, Alaska

A 1-day, late-summer reconnaissance of the Dietrich River, Alaska, determined species composition and diversity of benthic invertebrates and examined the correlation between stream order and invertebrate distribution. Benthic invertebrates were collected by dip net, drift net, and 10-rock collections, and results were combined for each station. Forty-nine taxa were identified from 5 stations representing stream orders 1 through 5. Aquatic insects comprised 88 percent of all taxa and 97 percent of all individuals from the Dietrich River. Diptera, especially Chironomidae, was the most abundant, followed by Plecoptera. Diamesinae was abundant at the headwaters, decreasing downstream; Orthocladiinae exhibited the reverse distribution pattern. Diversity of collections generally increased downstream. The station collections were compared using coefficients of similarity, cluster analysis, and taxonomy. Collections from adjacent stations were most similar and similarity decreased with increasing distance. The fauna was tentatively divided into zones with characteristic communities: a Diamesinae-Simuliidae fauna in zone I (stream order 1), zone II, a region of transition (orders 2-4), and an Orthocladiinae-Plecoptera-Ephemeroptera fauna in zone III (order 5). The fauna compares closely with that of other arctic streams. Although not conclusive, the benthic invertebrate results are consistent with the hypothesis that stream order is related to lotic biological communities.

Alaska↗
USGS1974

Major chemical characteristics of Mesozoic Coast Range ophiolite in California

Sixty-four major element analyses of rocks representative of the Coast Range ophiolite in California were compared with analyses of other onland ophiolite sequences and those of rocks from oceanic ridges. The rocks can be classed in five groups harzburgite-dunite, clinopyroxenite-wehrlite, gabbro, basalt-spilite, and keratophyre-quartz keratophyre which on various diagrams occupy nonoverlapping fields. The harzburgite-dunite from onland ophiolite and ocean ridges are comparable and very low in alkalies. Possible differentiation trends defined on AFM diagrams by other rocks from onland ophiolites and ocean ridges suggest two lines of descent: (1) A trend much like the calc-alkalic trend, though shifted somewhat toward higher iron, and (2) an iron-enrichment trend defined chiefly by the more iron-rich gabbros and amphibolite. MgO-variation diagrams for rocks from the Coast Range ophiolite further distinguish the iron-rich gabbros and amphibolite from the other rock groups and indicate that the iron enrichment, unlike that of the Skaergaard trend, is related to the formation of amphibole. Ophiolite sequences that include the most silicic rock types, such as quartz keratophyre, also exhibit the most pronounced dual lines of descent, suggesting that the silicic rocks and the amphibole-rich gabbros are somehow related. Although the major element chemistry of the Coast Range ophiolite is clearly like that of rocks dredged from oceanic ridges, it is not sufficiently diagnostic to discriminate among the choices of a spreading ridge, an interarc basin, or perhaps even the root zone of an island arc as the site of ophiolite formation.

California↗
USGS1974

Ultramafic rocks of the Eagle quadrangle, east-central Alaska

More than 97 separate occurrences of ultramafic rocks, some of which are included in a north west-trending zone of alpine-type ultramafic rocks, have been mapped in the Eagle quadrangle, east-central Alaska. They are divided into three groups primarily on the basis of degree of serpentinization. Group I consists of lens-shaped bodies of serpentinite 1 m 2 (10 ft 2 ) to several 100 m 2 (1,000 ft 2 ) in area. Relict textures and presence of bastite indicate that the original rock was harzburgite and dunite. Group II consists of bodies composed of partially serpentinized harzburgite and dunite and includes the large Mount Sorenson and American Creek bodies. Group III is dominantly hornblendite and pyroxenite, probably intrusive and not genetically related to groups I and II. The authors believe that the ultramafic bodies of groups I and II are alpine-type peridotites and may include dismembered ophiolitc. The Tintina fault system could have provided a zone of weakness along which mantle material was tectonically emplaced or it may have been a plate boundary in late Paleozoic time. If it represents a plate boundary, the metamorphic terrane which lies between the Tintina and Denali fault systems would have to be allochthonous, perhaps originating as a northward-moving slice of continental crustal material. During the course of the movement as the two continental masses approached and perhaps collided, mantle peridotite and oceanic crustal material were squeezed up along the continental margin onto the continental slice.

Alaska↗
USGS1974

Barium in hybrid granitoid rocks of the southern Snake Range, Nevada

In a magmatic environment, barium usually substitutes for potassium in the crystallizing silicates, and the two increase together in rocks late in the differentiation sequence. Results of this study show the opposite trend in an equivalent of a large part (63-76 percent SiO 2 ) of the classic differentiation sequence that resulted mainly from assimilation of chemically distinct host rocks. The barium content of the hybrid granitoid rock appears to be controlled mainly by the barium contents of the various sedimentary rock types assimilated.

Nevada↗
USGS1974

Distribution and occurrence of rare earths in the thorium veins on Hall Mountain, Idaho

Rare earths, although equal to or more abundant than thorium in many thorium veins, are much less abundant than thorium in the veins on Hall Mountain, Idaho. Total rare-earth content of these veins ranges from 0.00111 to 0.197 percent in 12 samples from 10 veins; the thoria (ThO 2 ) content, from 0.011 to 5.84 percent. The rare-earth oxide to thoria ratios range from 0.0019 to 3.22. Only two samples contained more rare earths than thorium, and these two samples came from veins related to a fault near the base of a thick sill; the others came from veins near the top of the same sill. The relative amounts of the individual lanthanides are remarkably similar in the Hall Mountain veins, although cerium, gadolinium, or dysprosium are the most abundant in different samples. These veins differ in lanthanide distribution both from the Earth's crust and from the thorium veins of the Lemhi Pass district, Idaho and Montana, in that they contain chiefly yttrium-group rare earths. Most of the rare earths occur in thorite, whose atomic structure will accommodate wide-ranging proportions of the rare earths. Cenosite, one of the few minerals with a high content of the yttrium group of rare earths, was found in one vein.

Idaho↗
USGS1974

Origin of spongy cherts

The spongy-textured surface in some cherts, visible on electron micrographs, is inherited from authigenic cristobalite. Spongy bedded cherts were originally bedded porcelanites similar to the porcelanite in the Miocene Monterey Formation of California.

Journal of Research of the U.S. Geological Survey↗