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At least 793 records · Page 44Linked to original sources
USGS1976

Bootstrap window, Elko and Eureka Counties, Nevada

The Bootstrap window in the Roberts Mountains thrust of north-central Nevada contains a 1,500-ft (460-m)- thick autochthonous section of carbonate assemblage rocks. These carbonate rocks include the upper part of the Roberts Mountains Formation and an unnamed limestone of Devonian age. They contain abundant material that must have been deposited in or near a reef. Allochthonous chert and shale of the siliceous assemblage, presumably Ordovician and Silurian in age, are present around the window and in a north-trending graben within the window. The Paleozoic rocks contain altered dikes, most of which may originally have been granodioritic. The localized recrystallization in the Paleozoic rocks probably occurred during dike emplacement. Sometime after the intrusion; both the dikes and their host rocks were epithermally altered. Some gold has been mined, and relatively high gold values (≥1 ppm) occur in rocks of the siliceous assemblage in and near the northern part of the steep north-trending fault zone on the west side of the graben. Areas of secondary alteration and of high values of silver and mercury are more widespread than the area of high gold values. The highest concentrations of silver and mercury, however, are also found near the same gold-bearing fault zone.

Nevada↗
USGS1976

Stratigraphic and hydrologic relationship of the Piney Point aquifer and the Alloway Clay Member of the Kirkwood Formation in New Jersey

Coarse quartzose (clastic) sediments of middle and late Eocene age in the subsurface of southern New Jersey are identified in this report as the Piney Point aquifer. The sediments are as thick as 220 feet (67 metres) and form a freshwater aquifer which is laterally continuous with the Piney Point aquifer of the Delmarva Peninsula. The Piney Point aquifer, in the area of Newport in Cumberland County, consists of fine to coarse glauconitic sand that is suggestive of deposition in a marginal marine beach environment. The aquifer tends to become finer grained with depth; coarse sand is dominant near the top of the aquifer, whereas, silt and clay are dominant near the base. The top of the aquifer- is marked by an angular unconformity. The hiatus between the upper Eocene sediments and the overlying Kirkwood Formation of middle Miocene age represents erosion during Oligocene and early Miocene time. The Alloway Clay Member, the basal unit of the Kirkwood Formation, rests unconformably on the Piney Point aquifer. It is a silty clay, dark brown to light tan, and contains abundant shell fragments and reworked greensand from the underlying Piney Point aquifer. The Alloway Clay Member, where present, acts as a confining unit for the Piney Point aquifer in southern New Jersey. Chemical analyses of water samples from the Piney Point aquifer in Cumberland County indicate a potential chloride problem in the aquifer near Delaware Bay. A water sample taken in 1973 at the Gandys Beach well contained 516 milligrams per litre of chloride, and a water sample taken in 1973 at the Money Island Marina well contained 73 milligrams per litre of chloride. Scant water-level data indicate the possibility of declining water levels in Cumberland County near Delaware Bay due to pumping from the Piney Point aquifer in Delaware. The altitude of the water level at well 16 is -3 feet (-1 metre), and the water-level altitude at well 11 is +23 feet (+7 metres).

New Jersey↗
USGS1976

Land subsidence and aquifer-system compaction in the San Jacinto Valley, Riverside County, California - A progress report

Widespread subsidence continues in the San Jacinto structural trough as water levels continue to decline. Subsidence is due principally to the compaction of water-bearing deposits as effective stresses are increased by artesian-head decline. Other possible contributory causes of subsidence are (1) local or regional tectonic adjustments and graben downfaulting, (2) natural compaction of deep water-bearing deposits below the bottom of well casings, and (3) continuing compaction of surficial deposits due to causes other than artesian-head decline. A careful analysis of 4 yr of correlative records of waterlevel, extensometer, and land-surface changes suggests three types of vertical ground movement occurring at the 4S/1W-21N2 recorder site near the San Jacinto reservoir site. The reservoir was drained in October 1973. Listed in descending order of magnitude these are (1) an elastic undulation of the land surface of about 0.06 ft (0.02 m) per year in close response to the roughly 50 ft (15 m) of seasonal water-level fluctuations, (2) a long-term permanent compaction of the deposits in the 0-1,237-ft (0-377-m) zone of about 0.04 ft (0.01 m) per year, and (3) a deep settlement of deposits below the 1,237-ft (377-m) extensometer anchor of 0.01-0.02 ft (0.003-0.006 m) per year, probably caused by continuing downfaulting in the graben trough. The specific compaction of the aquifer system at this site from 1970 to 1974 was about 1.3x 10 -2 (units of compaction per unit of increase in applied stress). The specific, expansion during this period decreased progressively from 1.29x 10 -3 (units of expansion per unit of stress decrease) in 1970-71 to 0.95x10 -3 in 1973-74, suggesting that excess pore pressures in the slow-draining aquitards were not completely dissipated each year.

California↗
USGS1976

Effects of air injection at Prompton Lake, Wayne County, Pennsylvania

Air injected into the hypolimnion of Prompton Lake at a maximum rate of 210 cubic feet per minute (6 cubic metres per minute) during a 65-day period (July 27 to September 30, 1973) produced the following results: (1) With cooler air temperatures prevailing, the mean subsurface temperature increased by 4.0° C compared with the same period in 1972, (2) although chemical and thermal destratiflcation was incomplete, 6 weeks of air injection increased the dissolved-oxygen concentration of the entire tropholytic zone to more than 4 milligrams per litre, (3) concentrations of nitrogen increased in the trophogenic zone during air injection, and (4) Anabaena flos-aquae attained cell concentrations in excess of 4,500 per millilitre during air injection.

Pennsylvania↗
USGS1978

Spectrophotometric determination of tungsten in rocks by using zinc-dithiol

Tungsten is determined in 11 USGS standard rocks by a spectrophotometric procedure that measures the absorbance of the tungsten-dithiol complex. The results are compared with those obtained by other methods. After the samples are dissolved in HClO 4 and HF, the tungsten-dithiol complex is extracted into isoamyl acetate and then back-extracted into isoamyl acetate. The determination of 0.1 part per million in a 500-mg sample can be made routinely.

Journal of Research of the U.S. Geological Survey↗
USGS1978

Solubility of highly soluble salts in aqueous media - Part 1, NaCl, KCl, CaCl 2 , Na 2 SO 4 , and K 2 SO 4 solubilities to 100°C

A modified visual method for determining the solubility of highly soluble salts in aqueous media up to 100° C is presented. The solubilities of NaCl, KCl, CaCl 2 , Na 2 SO 4 , and K 2 SO 4 were determined up to 100° C. The tabulated experimental data and the fitted equations describing the data indicate that the previous literature data for the solubility of these salts were generally high by 0.05 to 2.0 weight percent salt.

Journal of Research of the U.S. Geological Survey↗
USGS1978

Iron-titanium oxide minerals and associated alteration phases in some uranium-bearing sandstones

Detrital iron-titanium (Fe-Ti) oxide minerals of the ulvospinel-magnetite (titanomagnetite) and ilmenite-hematite (titanohematite) solid solution series are common in uranium-bearing sandstones. Alteration of Fe-Ti oxide minerals in oxidizing environments formed secondary products (primarily hematite) that are distinct from those produced under reducing conditions (iron disulfide minerals). Oxidation of sulfidized Fe-Ti oxide minerals, by the processes that formed uranium rolls, produced ferric oxide minerals (limonite) having textures that mimic those of the iron disulfides. Titanomagnetite and titanohematite have been severely depleted in the ore-bearing zones of some uranium deposits. The alteration of detrital Fe-Ti oxide minerals near uranium ore deposits may produce characteristic signatures in the magnetization of the sandstone. Knowledge of the distribution and magnetic properties of these minerals can aid in interpreting data from total magnetic-field and magnetic-susceptibility surveys of uranium deposits.

Colorado, New Mexico, Texas, Wyoming↗
USGS1978

Significance of age relations above and below upper jurassic ophiolite in the Geysers-Clear Lake region, California

In The Geysers-Clear Lake area of northern California, a fragmented Upper Jurassic ophiolite overlain depositionally by the Great Valley sequence is juxtaposed over deformed and metomorphosed rocks of the Franciscan assemblage along the Coast Range thrust. The basal strata of the Great Valley sequence consist of thick breccias of mafic clasts, identical in composition to the upper part of the ophiolite. These breccias and their contact relations suggest that more than 1 km of the upper part of the ophiolite was locally eroded in early Tithonian time. On the basis of their radiolarian faunas, cherts in the Franciscan assemblage below the ophiolite range in age from Late Jurassic (early Tithonian) to Late Cretaceous (early Cenomanian). Of particular significance is an individual chert body (= The Geysers chert) of this age range. The early Cenomanian radiolarians, except for two occurrences associated with pelagic limestone, are significantly younger than those previously reported from the Franciscan assemblage. The existence of a sequence of Late Jurassic to Late Cretaceous radiolarian chert places critical constraints on subduction models for emplacement of the Franciscan assemblage beneath the Coast Range ophiolite and Great Valley sequence in The Geysers-Clear Lake area. From early Tithonian to post-early Cenomanian time, the Franciscan assemblage received pelagic sedimentation far from any site of subduction. By other data, blueschist metamorphism of subducted Franciscan strata also occurred during this time. The radiolarian data from The Geysers area permit a correlation with Upper Cretaceous pelagic limestones in the Laytonville area northwest of The Geysers and also imply that the Great Valley sequence was never depositionally in contact with the Franciscan assemblage.

California↗
USGS1978

Age and composition of igneous rocks, Edna Mountain quadrangle, Humboldt County, Nevada

Six pulses of igneous activity ranging in age from Jurassic to Pliocene have been identified in the Edna Mountain quadrangle, Humboldt County, Nev. Porphyritic syenite am! quartz monzonite of Jurassic age (146-164 million years) at Buffalo Mountain are highly potassic through a wide range in SiO 2 content from olivine-bearing syenite to quartz-rich monzonite, and their composition contrasts sharply with plutons elsewhere in north-central Nevada. Granodiorite and quartz monzonite plutons of Cretaceous age (88- 106 m.y.) are chemically and mineralogically similar to other calc-alkaline plutons in north-central Nevada. Four episodes of Tertiary volcanism include rhyolite ashflow tuffs and slightly younger andesitic basalt flows and tuffs of Oligocene age, rhyolite vitrophyre of late Miocene age, and olivine basalt flows of Pliocene age. Their age and mineralogical and chemical compositions are similar to other Tertiary volcanic rocks in north-central Nevada.

Nevada↗
USGS1978

Pressure gradients and boiling as mechanisms for localizing ore in porphyry systems

Fluid inclusions in ore zones of porphyry systems indicate that extensive boiling of hydrothermal fluids accompanies deposition of ore and gangue minerals. The boiling commonly accompanied a change from a lithostatic to a hydrostatic environment during evolution of an epizonal stock. Pressure gradients near the margin of the stock can determine whether ore or only a diffuse zone of mineralization is formed. A sharp drop in pressure in an epizonal environment is more likely to cause extensive boiling than a comparable change in a deeper environment, as the slope of the boiling curve steepens with an increase 'in pressure. The drop in pressure causes the hydrothermal fluids to boil and creates a crackle (stockwork) breccia, which hosts the veinlets of gangue quartz and ore minerals. The boiling selectively partitions CO 2 , H 2 S, and HCl into the vapor phase, changing the pH, composition, ionic strength, and thus the solubility product of metal complexes in the remaining liquid and causing the ore and gangue to come out of solution. Fluid inclusions trapped from boiling solutions can exhibit several forms, depending on the physical and chemical conditions of the hydrothermal fluid from which they were trapped. In one case, inclusions when heated can homogenize to either liquid or vapor at the same temperature, which is the true boiling temperature. In another case, homogenization of various inclusions can occur through a range of temperatures. The latter case results from the trapping of mixture of liquid and vapor. Variations in salinity can result from boiling of the hydrothermal fluid, or intermittent incorporation of high-salinity fluids from the magma, or trapping of fluids of varying densities at pressure-temperature conditions above the critical point of the fluid. In places, paleopressure-temperature transition zones can be recognized by fluid-inclusion homogenization temperatures and phase relationships and by the presence of anhydrite daughter minerals. Boiling of a hydrothermal fluid in the porphyry environment affects light stable isotopes. Hydrogen is preferentially fractionated into the vapor phase from water boiling below 223°C; above this temperature deuterium is selectively enriched in the vapor phase. In certain environments boiling creates a vapor-dominated system in which the condensate is swept away by meteoric waters and the H/D in the residual fluids is progressively increased through time.

Utah↗
USGS1978

Phosphorus in hydrothermal waters of Yellowstone National Park, Wyoming

Ninety-seven hot-spring and geyser samples (field acidified to pH<1.4 with HCl or HNO 3 ) from Yellowstone National Park, Wyo., were analyzed for PO 4 -P using reduced molybdenum-blue and the selective arsenate reducing agent, metabisulfite-thiosulfate. The PO 4 -P concentrations ranged from below detection limit (~1-73 micrograms per liter). Twenty-five springs had PO 4 -P concentrations exceeding 6.8 &mu; g/L; seven spring samples exceeded 20 &mu;g/L. Elevated PO 4 -P contents were invariably associated with mixed springs, as evidenced by diluted chloride concentrations and, commonly, subboiling temperatures, low pH's, and elevated calcium concentrations. Alkaline high-chloride (>400 milligrams per liter) hydrothermal waters from Upper and Norris Geyser Basins had PO 4 -P concentrations below 2 &mu;g/L and represent the low end of the range of PO 4 -P contents in natural waters.

Wyoming↗
USGS1978

Conductive heat flows in research drill holes in thermal areas of Yellowstone National Park, Wyoming

In convection systems with boiling springs, geysers, fumaroles, and other thermal features, the modes of heat flow become increasingly complex as a single liquid phase at depth rises into the near-surface environment where heat flows by convection of liquid and vapor and by conduction in high thermal gradients. This paper is mainly concerned with the changing patterns of conductive heat flow as related to channels of subsurface convective flow and to horizontal distance from spring vents. The primary data consist of temperatures measured in 13 cored drill holes as drilling progressed. Some temperatures plot convincingly on straight-line segments that suggest conductive gradients in rocks of nearly constant thermal conductivity. Temperature gradients and the conductive component of total heat flow nearly always decrease drastically downward; the gradient and heat flow of the lowest depth interval recognized in each hole is commonly only about 10 percent of the highest interval; the changes in gradient at interval boundaries are commonly interpreted as channels of near-boiling water or of cooler meteoric water. Temperature reversals are probably related to inflowing cooler water rather than to transient effects from recent changes. Some temperatures plot on curved segments that probably indicate dispersed convective upflow and boiling of water in ground penetrated by the drill hole. Other similar curved segments are too low in temperature for local boiling and are probably on the margins of hot upflow zones, reflecting conductive cooling of flowing water. The conifers of Yellowstone National Park (mainly lodgepole pine) seem to have normal growth characteristics where near-surface conductive heat flow is below about 200 heat-flow units (1 HFU = 10 -6 cal/cm 2 = 41.8 mW/m 2 ). Most areas of abnormal "stunted" trees (low ratio of height to base diameter, and low density of spacing) are characterized by conductive heat flows of about 250 to 350 HFU. The critical factor affecting growth is probably the seasonal maximum soil temperature at the root depths preferred by each form, rather than the heat flow as such. Heat flows up to 300 HFU are greatly dominated near the surface by conduction and are little affected by convection within the measured intervals. With increasing total heat flow above 300 HFU, the convection component, as indicated by snowfall calorimetry, becomes increasingly important. Snowfall calorimetry and tree growth as related to heat flow are calibrated by the heat-flow data considered here. Both snowfall calorimetry and tree growth patterns can be extrapolated rapidly, although without high precision, to thermal areas that lack subsurface data.

Wyoming↗
USGS1978

Upper Devonian radiolarians separated from chert of the Ford Lake Shale, Alaska

Leaching of black bedded chert from the Ford Lake Shale, Kandik Basin, Alaska, with dilute hydrofluoric acid resulted in the complete separation of moderately well preserved radiolarians. Preliminary study of an assemblage obtained from the lower half of the formation revealed six to eight forms apparently identical to specimens previously known from the Tournaisian of southern France and northwestern Turkey, including four genera not previously described from North America. Sparse, poorly preserved conodonts in the same sample are of Late Devonian age. We conclude that certain radiolarian species, hitherto known only from the early Carboniferous, span the Devonian-Carboniferous boundary. The radiolarian assemblage of the Ford Lake Shale sample contrasts markedly with Late Devonian assemblages known from the Canol Shale of northern Canada and the Huron Member of the Ohio Shale; the Ford Lake Shale fauna may reflect greater oceanic influences than these other localities, which lie farther inland from the Devonian continental margin.

Alaska↗
USGS1978

A reexamination of the Pennsylvanian trace fossil Olivellites

The original interpretation of Olivellites plummeri Fenton and Fenton as the trace of an infaunal gastropod, is reconsidered and rejected. The original slab bearing several examples of O. plummeri has been reexamined and reillustrated. The slab came from the type-locality of O. plummeri in Eastland County, Tex., and is a shallow sub tidal sandstone of the Graham Formation; the sandstone, which has yielded additional specimens, is presumably a reworked delta-front deposit. Olivellites was also observed in the Caddo Creek Formation in Stephens County, Tex., but, to date, it has not been found elsewhere in north-central Texas. Interpretation of Paleozoic ichnofossils by analogy with modern traces is limited; behavioral characteristics may be the products of post-Paleozoic innovation. The internal morphology and path of Olivellites are unlike those of any modern gastropod trail, and the genus is removed from the Mollusca.

Texas↗
USGS1978

lowaphyllum (rugose coral) from the Upper Devonian of Arizona

The rugose coral genus lowaphyllum is uncommon but widely distributed in rocks of Devonian age. It is here reported for the first time from western North America (Late Devonian). lowaphyllum is also known from the late Middle and Late Devonian of Eastern North America, but the lack of Early and early Middle Devonian species anywhere in North America leaves open the question of derivation of these forms and their relationship to Early Devonian species in Europe and Australia.

Arizona↗
USGS1978

Inventory of land use and land cover of the Puget Sound region using Landsat digital data

Landsat multispectral scanner digital data from four bands were analyzed using computers to produce land use and land cover information of the Puget Sound region, Wash., for use by agencies in that area. The data were first geographically registered to map coordinates. This registration enabled samples of known land cover types to be digitized from the maps. Samples of the same land cover were grouped together and then subdivided by cluster analysis into spectrally similar classes. Spectral categories were associated with specific land cover classes and used to determine spectral signatures for classification of the entire region. Reclustering and reclassification techniques were developed and then employed to minimize certain classification errors. The classified data were displayed in color using a film recorder. This color image was enlarged photographically to a 1:100000 scale to match new base maps of the region. Although the result resembles a conventional polygonal land use and land cover map, certain image-like qualities remain and yield additional information about the landscape.

Washington↗
USGS1978

Application of four input-output models for nutrients in Lake Okeechobee, Florida

R. A. Vollenweider's (1975) nonconservative model described concentrations of nitrogen and phosphorus for 1969-70 in Lake Okeechobee, Fla., better than the models of F. Biffi in 1963, R. H. Rainey in 1967, and R. Piontelli and V. Tonolli in 1964. Vollenweider's model predicted concentrations of 1.4 milligrams per liter of total nitrogen and 0.09 mg/L of total phosphorus in the lake. The concentration of nitrogen could be approximated with conservation models but phosphorus required a nonconservative model. Unless variations in input concentrations and flow rate of the tributaries are modeled, only short-term predictions of lake concentrations can be made because of variations in inflow concentrations and because of the short time required (400 days) for the lake to be flushed by its inflow.

Florida↗
USGS1978

Reconnaissance for microbial activity in the Magothy aquifer, Bay Park, New York, four years after artificial recharge

Tertiary-treated sewage effluent was injected into the Magothy aquifer at Bay Park, Long Island, N.Y., between 1968 and 1973. In 1977, the microbial flora in water samples from the injection well and from three nearby wells were surveyed. Differences in the composition of the microbial flora among the four wells were found. A bacterial community dominated by facultative and obligate anaerobes, including two Clostridium species and methanogenic bacteria, was found at a well 6.1 m from the injection well. By contrast, except for isolation of Clostridium sphenoides from a well 30 m away, only obligate aerobes and facultative anaerobes were found in water from the injection well and the 30 m well. Only a small number of obligate aerobes were found in samples from a well 61 m away. These results suggest that nutrients in the recharge water formed an organically enriched zone to at least a distance of 6.1 m from the point of injection but not as far as 61 m. Extensive pumping at the end of the injection program apparently removed exogeneous nutrients near the injection well.

New York↗