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At least 649 records · Page 36Linked to original sources
USGS2020

Batch extraction method to estimate total dissolved solids (TDS) release from coal refuse and overburden

A rapid batch extraction method was evaluated to estimate potential for total dissolved solids (TDS) release by 65 samples of rock from coal and gas-bearing strata of the Appalachian Basin in eastern USA. Three different extractant solutions were considered: deionized water (DI), DI equilibrated with 10% CO 2 atmosphere (DI + CO 2 ), or 30% H 2 O 2 under 10% CO 2 (H 2 O 2 +CO 2 ). In all extractions, 10 g of pulverized rock (<0.5-mm) were mixed with 20 mL of extractant solution and shaken for 4 h at 50 rpm and 20–22 °C. The 65 rock samples were classified as coal (n=3), overburden (n = 17), coal refuse that had weathered in the field (n = 14), unleached coal refuse that had oxidized during indoor storage (n = 20), gas-bearing shale (n = 10), and pyrite (n = 1). Extracts were analyzed for specific conductance (SC), TDS, pH, and major and trace elements, and subsequently speciated to determine ionic contributions to SC. The pH of extractant blanks decreased in the order DI (6.0), DI + CO 2 (5.1), and H 2 O 2 +CO 2 (2.6). The DI extractant was effective for mobilizing soluble SO 4 and Cl salts. The DI + CO 2 extractant increased weathering of carbonates and resulted in equivalent or greater TDS than the DI leach of the same material. The H 2 O 2 +CO 2 extractant increased weathering of sulfides (and carbonates) and resulted in the greatest TDS production and lowest pH values. Of the 65 samples, 19 had leachate chemistry data from previous column experiments and 35 were paired to 10 field sites with leachate chemistry data. When accounting for the water-to-rock ratio, TDS from DI and DI + CO 2 extractions were correlated to TDS from column experiments while TDS from H 2 O 2 +CO 2 extractions was not. In contrast to column experiments, field SC was better correlated to SC measured from H 2 O 2 +CO 2 extractions than DI extractions. The field SC and SC from H 2 O 2 +CO 2 extractions were statistically indistinguishable for 7 of 9 paired data sets while SC from DI extractions underestimated field SC in 5 of 9 cases. Upscaling comparisons suggest that (1) weathering reactions in the field are more aggressive than DI water or synthetic rainwater extractants used in batch or column tests, and (2) a batch extraction method utilizing 30% H 2 O 2 (which is mildly acidic without CO 2 enrichment) could be effective for identifying rocks that will release high amounts of TDS.

Applied Geochemistry↗
USGS2009

The Sudbury impact layer in the paleoproterozoiciron ranges of northern Michigan, USA

A layer of breccia that contains fragments of impact ejecta has been found at 10 sites in the Paleoproterozoic iron ranges of northern Michigan, in the Lake Superior region of the United States. Radiometric age constraints from events predating and postdating deposition of the breccia are ca. 1875 Ma and 1830 Ma. The major bolide impact that occurred at 1850 Ma at Sudbury, Ontario, 500–700 km east of these sites, is the likely causative event. The Michigan sites described here, along with previously described sites in Minnesota and Ontario, define an extensive ejecta-bearing deposit throughout the Paleoproterozoic iron ranges of the Lake Superior region that we refer to as the Sudbury impact layer. The layer at the sites in Michigan exhibits a range of thicknesses, lithologic characters, and sedimentary settings. The diversity of rock types and internal stratigraphic details of the layer imply that several different processes of transport and deposition are represented, but the detailed investigations needed to document them are incomplete. Many of the sites had been described and interpreted previously as products of common terrestrial processes, but the presence of relict shock-induced planar deformation features in quartz indicates that the breccia layer is in fact the product of an extraterrestrial impact. At most localities, this layer also contains relict fragments of altered devitrified glass and/or accretionary lapilli. One immediate use of the impact layer is as an ultraprecise time line that ties together the well-known stratigraphic sequences of the various geographically separated iron ranges, the correlation of which has remained controversial for many decades. The Sudbury impact layer most commonly lies at a horizon that records a significant change in the character of sediments across the region. The impact layer marks the end of a major period of banded iron formation deposition that was succeeded by deposition of fine clastic rocks, commonly black shales. The impact may have produced regional, if not global, changes in the environment that resulted in this widespread synchronous change in sedimentation style.

Geological Society of America Bulletin↗
USGS2004

The geochemical and magnetic record of coal combustion products in West Virginia reservoir sediments and soils

Western West Virginia lies downwind from numerous coal-fired power plants along the Ohio River Valley. To test whether geochemical and mineralogical impacts from these power plants are detectable on the West Virginia landscape, we obtained reservoir cores, soils, and rocks from two separate sites in West Virginia, one in Harrison County (Hinkel and Deegan Reservoirs) and the other in Roane County (Miletree Run Reservoir). Both have small drainage basins that have the effect of maximizing atmospheric inputs relative to weathering inputs. Sediments from Hinkel Reservoir were dated using the 137 Cs method, and by knowledge of the age of the base of the sedimentary section. Major elements in Hinkel Reservoir sediments do not vary systematically over time, suggesting that the depositional history of these sediments has been relatively constant. In contrast, minor elements and sulfur do show dramatic shifts. Zn, Pb, As, S, Cd, Ge, and Hg all peak during the late 1960s and early 1970s. Polyaromatic hydrocarbons associated with combustion processes likewise show this same behavior. Coincident with these maxima is a peak in isothermal remnant magnetization (IRM), a parameter that is proportional to magnetite abundance. We separated the magnetic fraction of the sediments and examined this fraction petrographically. It is dominated by magnetite with a spherical morphology, which is characteristic of magnetite produced by combustion processes. Chemical analyses on local rocks showed that they were not the likely source for the trace element and magnetite enrichments. To compare soils and reservoir sediments, we normalized geochemical data to Ti; the underlying assumption is that Ti will track physical inputs of soil materials into the reservoir sediments. The normalized sediment data for the elements Zn, Pb, As, and S are all higher for sediments deposited during the late 1960s and early 1970s compared to normalized soil data, implying that soils are not the source for the element enrichments. We thus attribute the enrichment to atmospheric inputs. However, a coal-burning zinc smelter within 10 km of the reservoir site that operated until 1971 may have supplied some or all of the anomalous input: There are no nearby major atmospheric pollution sites near Miletree Run Reservoir. A core from this reservoir was dated based on knowledge of the time it was impounded. Like Hinkel Reservoir, there are no systematic shifts in major element contents over its depositional history. Like Hinkel Reservoir, there are also significant shifts in trace elements and IRM that cannot be explained by local soil sources. Magnetic separates from this reservoir are also dominated by spherical combustion-produced magnetite. Covariance over the period 1930-1980 between magnetite and sulfur with US SO 2 production (which comes dominantly from coal combustion) is strongly suggestive of a significant atmospheric input into Miletree Run Reservoir sediments. The nearest upwind power plants are between 50 and 75 km distant. Thus, relatively long distance transmission of particulate matter from the power plants of the Ohio River Valley is likely in this case.

West Virginia↗
USGS2013

Macroinvertebrate diets reflect tributary inputs and turbidity-driven changes in food availability in the Colorado River downstream of Glen Canyon Dam

Physical changes to rivers associated with large dams (e.g., water temperature) directly alter macroinvertebrate assemblages. Large dams also may indirectly alter these assemblages by changing the food resources available to support macroinvertebrate production. We examined the diets of the 4 most common macroinvertebrate taxa in the Colorado River through Glen and Grand Canyons, seasonally, at 6 sites for 2.5 y. We compared macroinvertebrate diet composition to the composition of epilithon (rock and cliff faces) communities and suspended organic seston to evaluate the degree to which macroinvertebrate diets tracked downstream changes in resource availability. Diets contained greater proportions of algal resources in the tailwater of Glen Canyon Dam and more terrestrial-based resources at sites downstream of the 1st major tributary. As predicted, macroinvertebrate diets tracked turbidity-driven changes in resource availability, and river turbidity partially explained variability in macroinvertebrate diets. The relative proportions of resources assimilated by macroinvertebrates ranged from dominance by algae to terrestrial-based resources, despite greater assimilation efficiencies for algal than terrestrial C. Terrestrial resources were most important during high turbidity conditions, which occurred during the late-summer monsoon season (July–October) when tributaries contributed large amounts of organic matter to the mainstem and suspended sediments reduced algal production. Macroinvertebrate diets were influenced by seasonal changes in tributary inputs and turbidity, a result suggesting macroinvertebrate diets in regulated rivers may be temporally dynamic and driven by tributary inputs.

Arizona↗
USGS2006

Crater gradation in Gusev crater and Meridiani Planum, Mars

The Mars Exploration Rovers investigated numerous craters in Gusev crater and Meridiani Planum during the first ???400 sols of their missions. Craters vary in size and preservation state but are mostly due to secondary impacts at Gusev and primary impacts at Meridiani. Craters at both locations are modified primarily by eolian erosion and infilling and lack evidence for modification by aqueous processes. Effects of gradation on crater form are dependent on size, local lithology, slopes, and availability of mobile sediments. At Gusev, impacts into basaltic rubble create shallow craters and ejecta composed of resistant rocks. Ejecta initially experience eolian stripping, which becomes weathering-limited as lags develop on ejecta surfaces and sediments are trapped within craters. Subsequent eolian gradation depends on the slow production of fines by weathering and impacts and is accompanied by minor mass wasting. At Meridiani the sulfate-rich bedrock is more susceptible to eolian erosion, and exposed crater rims, walls, and ejecta are eroded, while lower interiors and low-relief surfaces are increasingly infilled and buried by mostly basaltic sediments. Eolian processes outpace early mass wasting, often produce meters of erosion, and mantle some surfaces. Some small craters were likely completely eroded/buried. Craters >100 m in diameter on the Hesperian-aged floor of Gusev are generally more pristine than on the Amazonian-aged Meridiani plains. This conclusion contradicts interpretations from orbital views, which do not readily distinguish crater gradation state at Meridiani and reveal apparently subdued crater forms at Gusev that may suggest more gradation than has occurred. Copyright 2006 by the American Geophysical Union.

Journal of Geophysical Research E: Planets↗
USGS2012

Volcanism, isostatic residual gravity and regional tectonic setting of the Cascade volcanic province

A technique to locate automatically boundaries between crustal blocks of disparate densities was applied to upward continued isostatic residual gravity data. The boundary analysis delineates a narrow gravitational trough that extends the length of the Pliocene and Quaternary volcanic arc from Mount Baker in northern Washington to Lassen Peak in California. Gravitational highs interrupt the trough at two localities: a northwest trending high in southern Washington and a northeast trending high between Mount Shasta and Lassen Peak. The latter anomaly is one of a set of northeast trending anomalies that, within the Quaternary arc, appear related to volcanic segmentation proposed previously on the basis of spatial and compositional distributions of volcanoes. These northeast trending anomalies extend hundreds of kilometers northeast of the arc, are caused by sources in the upper crust, and in some cases are related to exposed pre-Tertiary rocks. Segmentation models invoke geometric characteristics of the subducting plate as the primary factor controlling location and chemistry of volcanism, and these northeast trending gravity sources also may be a product of disturbance of the upper crust by the subduction process. More likely, the gravity sources may reflect upper crustal structures older than the High Cascades, possibly relicts from earlier accretionary events or more recent crustal deformation, that have actively influenced the spatial location of more recent volcanism. Much of the Pliocene and Quaternary volcanism of the Cascade arc has concentrated on or near contacts between crustal blocks of disparate density. These contacts may promote the ascension of magma to the Earth's surface.

Journal of Geophysical Research Solid Earth↗
USGS1978

Origin of a South Texas roll-type uranium deposit; I, Alteration of iron-titanium oxide minerals

The detrital Fe-Ti oxide minerals and their authigenic alteration products in samples from cores spanning 1.7 km across a roll-type uranium deposit in the mid-Tertiary Catahoula Tuff, south Texas, record important information on host-rock preparation and on development of the altered tongue of the deposit. In reduced rock, in front of and enveloping the altered tongue, iron disulfide minerals (pyrite and marcasite) have partially to completely replaced titanomagnetite and, to a lesser extent, titanohematite. Subsequent oxidation of these sulfidized Fe-Ti oxides, by processes that formed the altered tongue and uranium roll, produced ferric oxide and hydroxide phases (limonite) pseudomorphous after the sulfides. Fe-Ti oxides 1.0 km updip from the roll front were never sulfidized; titanomagnetite (partly replaced by hematite) and martite constitute nearly half of the heavy mineral fraction and limonite is absent. Oxidized rocks 210 m and closer to the nose of the roll front, however, are nearly devoid of titanomagnetite and contain abundant limonite. The redox interface that bounds the altered tongue, therefore, moved more than 210 m but less than 1.0 km. Detrital Fe-Ti oxide minerals are increasingly sulfidized in the downdip direction indicating that initial sulfidizaton was more intense in that direction. Organic carbon content is uniformly very low throughout the host sandstone, which implies that heterotrophic sulfate-reducing bacteria were not involved in the generation of sulfide. The H 2 S for the initial sulfidization may have been derived from oil and gas in formations that underlie the Catahoula Tuff. The H 2 S probably invaded the Catahoula along a fault that is 1.5 km downdip from the present roll front.

Texas↗
USGS1980

Intrusions and intrusive complexes in an ophiolite near San Luis Obispo; a chemical and petrologic study

The San Luis Obispo ophiolite is a sequence of mafic and ultramafic rocks that lie as a thrust-like slice on top of Franciscan melange in the southern California Coast Range. The ophiolite comprises the classic Steinmann Trinity of basal serpentinized ultramafic rocks overlain sequentially by spilitized pillow lavas and cherts. The ophiolite is intruded by numerous diabasic dikes and several large intrusive complexes that contain peridotite, gabbro, diabase and felsic rocks. Field relations indicate that this ophiolite originated as a sequence of submarine volcanic flows and breccia units extruded onto an ultramafic basement. Later the volcanic and ultramafic rocks were intruded along their contact by mafic magma that crystallized as a stratiform complex of cumulate peridotite and gabbro. Next, this stratiform complex was intruded by diorite and albite-granite (trondhjemite) sills, which may have been produced by partial melting of gabbros in the upper levels of the stratiform complex. Finally all earlier units were intruded by diabasic sills and dikes that probably were late feeders for the pre-existing volcanic unit. All the ophiolite rocks underwent subsequent highly localized brecciation, under greenschist-facies conditions, in which felsic rocks were incipiently melted by frictional heating. The host rocks and intrusions were metamorphosed at low temperature and the mafic rocks were altered by Na- and Si-metasomatism. Despite this pervasive alteration, evidences of the formational stages of the ophiolite are preserved in disequilibrium mineral assemblages, primarily within mafic and ultramafic rocks of the intrusive complexes. Whole-rock analyses of the ophiolite suite indicate that alteration has obscured but not obliterated the original chemical character of the mafic rocks. The ophiolite diabases and basalts contain up to 6 weight percent Na 2 0 and 58 percent Si0 2 , in contrast to normal Si0 2 contents of 50 percent or less and Na 2 0 contents of less than 3 percent for unaltered oceanic and continental tholeiite basalts. However, the low K 2 0 contents (less than 0.8 percent) of all units in the ophiolite suite indicate that these rocks are not part of an alkalic kindred, but rather are altered tholeiites. Compositions of relict amphibole and plagioclase in the mafic rocks indicate that the ophiolite formed in a high-temperature environment and the deep seated rocks were metamorphosed under amphibolite-facies conditions. A later change in the environmental conditions allowed subsequent low-temperature (greenschist facies) metamorphism and metasomatism. The structure and chemistry of the San Luis Obispo ophiolite support the hypothesis that this body may represent a fragment of oceanic crust and mantle. The volcanic rocks and the intrusive complexes probably formed at a mid-ocean ridge, where conditions of high heat-flow provided the requisite high-temperature environment and promoted the production of mafic magmas. The change to low-temperature conditions probably was due to inception or acceleration of crustal spreading at that portion of the ridge where this ophiolite formed. The nature of brecciation in the ophiolite indicates that the low-temperature environment also was one of greater tectonic disturbance, relative to conditions at the ridge. This tectonically active environment probably corresponds to an island arc where the ophiolite-bearing plate was subducted in an adjacent trench. The absence of a high-pressure mineral assemblage in the San Luis Obispo ophiolite suggests that this segment of ocean-crust and upper mantle was not buried in a subduction zone, but rather was rafted on top of subduction melange (Franciscan Formation) into its present position.

California↗
USGS1990

Hydrology and land use in Grand Traverse County, Michigan

Glacial deposits are the sole source of ground-water supplies in Grand Traverse County. These deposits range in thickness from 100 to 900 feet and consist of till, outwash, and materials of lacustrine and eolian origin. In some areas, the deposits fill buried valleys that are 500 feet deep. Sedimentary rocks of Paleozoic age, which underlie the glacial deposits, are mostly shale and are not used for water supply. Of the glacial deposits, outwash and lacustrine sand are the most productive aquifers. Most domestic wells obtain water from sand and gravel at depths ranging from 50 to 150 feet and yield at least 20 gallons per minute. Irrigation, municipal, and industrial wells capable of yielding 250 gallons per minute or more are generally greater than 150 feet deep. At places in the county where moranial deposits contain large amounts of interbedded silt and clay, wells are generally deeper and yields are much lower. Areal variations in the chemical and physical characteristics of ground and surface water are related to land use and chemical inputs to the hydrologic system. Information on fertilizer application, septic-tank discharges, animal wastes, and precipitation indicate that 40 percent of nitrogen input is from precipitation, 6 percent from septic tanks, 14 percent from animal wastes, and 40 percent from fertilizers. Streams and lakes generally have a calcium bicarbonate-type water. The dissolved-solids concentration of streams ranged from 116 to 380 milligrams per liter, and that of lakes, from 47 to 170 milligrams per liter. Water of streams is hard to very hard; water of lakes ranges from soft to hard. The maximum total nitrogen concentration found in streams was 4.4 milligrams per liter. Water of lakes have low nitrogen concentrations; the median nitrate concentration is less than 0.01 milligrams per liter. Pesticides (Parathion and Simazine) were detected in low concentrations at six stream sites; 2,4-D was detected in low concentrations in water of two lakes. Relationships between land use and the yield of dissolved and suspended substances could not be established for most stream basins. Calcium and bicarbonate are the principal dissolved substances in ground water. Dissolved-solids concentrations ranged from 70 to 700 milligrams per liter; the countywide mean concentration is 230 milligrams per liter. The mean nitrate concentration is 1.3 milligrams per liter; about 1.6 percent of the county's ground water has nitrate concentrations that exceed the U.S. Environmental Protection Agency's maximum drinking water level of 10 milligrams per liter. An effect of fertilizer applications on ground-water quality is evident in some parts of the county.

Michigan↗
USGS2002

Preliminary geophysical characterization of two oil production sites, Osage County, Oklahoma - Osage Skiatook Petroleum Environmental Research Project

Ground electromagnetic and dc resistivity geophysical surveys were used to interpret the subsurface distribution of salinized soil, water, and bedrock at two sites (A and B) and to characterize the larger scale hydrologic setting. Measurements were made on grids of about 1000 square meters using a very shallow penetrating (less than 10 m) electromagnetic (EM) geophysical system (EM31). At site A, high subsurface conductivities (more than 100 millisiemens per meter) found below disposal ponds extended down the local hydrologic gradient to below the normal level of near by Lake Skiatook. At site B, areas of highest subsurface electrical conductivity were offset about 10 m from the center of salt scars. The area of high subsurface electrical conductivity extends in the subsurface below the normal level of Skiatook Lake. DC resistivity soundings were made in and around the two sites in order to characterize deeper (30-60 m) electrical properties of the subsurface lithology and ground water. These soundings indicate that the tight shale that dominates the local lithology is moderately electrically conductive (5 milliseimems per meter). DC soundings done in several areas at the Skiatook Lake shoreline indicate an electrically conductive (less than 10 millisiemens per meter) zone exists below the shore even away from the oil production sites. This conductive zone may indicate a mixing between fresh lake water and local ground water that has high dissolved solids. Borehole geophysical logs at site B and laboratory rock property measurements are currently being used to refine interpretation of ground geophysical measurements.

Oklahoma↗
USGS2004

Selenium loading through the Blackfoot River watershed--linking sources to ecosystem

The upper Blackfoot River watershed in southeast Idaho receives drainage from 11 of 16 phosphate mines that have extracted ore from the Phosphoria Formation, three of which are presently active. Toxic effects from selenium (Se), including death of livestock and deformity in aquatic birds, were documented locally in areas where phosphatic shales are exposed ( Piper et al., 2000 ; Presser et al., Chapter 11). Current drainage conditions are leading to Se bioaccumulation at concentrations that pose a risk to fish in the Blackfoot River and its tributaries (Hamilton et al., Chapter 18). A gaging station on the Blackfoot River was re-activated in April 2001 to assess hydrologic conditions and concentration, load, and speciation for Se discharges on a watershed scale. The gaging-station data are considered to represent regional drainage conditions in the upper Blackfoot River water- shed because of its location near the outlet of the watershed and directly upstream of the Blackfoot Reservoir. Watershed discharges for 2001 and 2002 were below minimum hydrologic conditions for the gage as documented by the historical record. Drought emergencies were declared in the area in both 2001 and 2002. Unmonitored diversions for irrigation that routinely take place during the snowmelt season also affected conditions downstream. Annual cycles in Se concentration, load, and selenate (Se 6+ ) reached maxima in the spring during the period of maximum flow at the gaging station. Thirty-seven to 44% of annual flow occurred dur- ing the three-month high-flow season (April through June) in 2001 and 56% of annual flow occurred during that time period in 2002. Extrapolation from historical hydrographs for average and wet years and a limited data set of regional Se concentrations for 2001 and 2002 indicated potential for a 3.6- to 7.4-fold increase in Se loading because of increased seasonal flows in the Blackfoot River watershed. Supplementation data indicate that: (a) the difference between total Se and dissolved Se, as a measure of the contribution of particulate Se, was < 10% except at the peak of con- centration when total Se was 18% more than dissolved Se; (b) selenite (Se 4+ ) represented less than 10% of the dissolved species during all months of 2001; and (c) dissolved Se was approximately a 50:50 mixture of selenate and organic selenide (operationally defined Se 2- ) during summer 2001 (June through August). Ecological risk based on regional Se drainage occurred during both the high- and low-flow seasons. Seventy to 83% of the Se load occurred during the high-flow season. During early May of both years, dissolved-Se concentrations exceeded the criterion for the protection of aquatic life and the ecological threshold of 5 gL 1 Se at which sub- stantive risk occurs. During the majority of the three-month high-flow season, dissolved- Se concentrations exceeded the 2 gL 1 Se concern level for aquatic biota. The Se concentration in suspended material during high flow in 2002 was within the range of marginal risk to aquatic life (2-4 gg 1 Se, dry weight). Selenate was the major species during peak flows, with both selenate and organic selenide being major species during relatively low-flow periods in summer. A change in speciation to reduced Se may indicate elevated biotic productivity during summer months and could result in enhanced Se uptake in food webs. In addition to the magnitude of regional Se release in the Blackfoot River watershed, Se concentrations in individual source drains and waste-rock seeps, and those predicted by experimental column leaching of proposed mining overburden materials, also indicate that drainage options that currently meet existing demands for phosphate mining cause eco- logical risk thresholds to be exceeded. At times, the drinking-water Se standard (50 g L 1 Se) and the criterion for hazardous Se waste (1000 L -1 Se) ( US Department of the Interior, 1998 ; US Environmental Protection Agency, 1987 ) are also exceeded. For water-years 2001 and 2002, seasonal increased input of water in the mining area resulted in increased Se transport, suggesting a mechanism of contamination that involves a significant Se reservoir. Hence, recognition and monitoring of Se loading to the envi- ronment on a mass balance basis (i.e. inputs, fluxes and storage within environmental media, and outputs) are essential to evaluating how to control Se concentrations within environmentally protective ranges ( Presser and Piper, 1998 ). In areas where release of Se to aquatic systems is anticipated as a product of future expansion of phosphate mining, continuous monitoring of flow and development of seasonal Se loading patterns would help to model watersheds in terms of sources, flow periods, and environmental-Se con- centrations that most influence bioavailability. These data, in turn, could be linked to Se- bioaccumulation models specific to food webs and vulnerable species of the impacted areas to accurately project ecological effects. Gaging at this site on the Blackfoot River is planned to continue in order to establish a long-term (>10 year) record of hydrologic conditions.

Idaho↗
USGS2019

The Kulanaokuaiki-3 tephra, 900 CE: Products of a remarkably energetic pyroclastic eruption at Kīlauea Volcano, Hawaiʻi, USA

Eruptions of Kīlauea Volcano, Hawaiʻi, USA, can be more powerful than previously recognized. The Kulanaokuaiki-3 (K-3) eruption, ca. 900 CE, consisted of two episodes that dispersed lithic wall-rock clasts (Episode 1) and dominantly scoria (Episode 2; VEI-3) across >65 km 2 southeast of the summit. Dense 12 cm blocks of Episode 1 fell 8–10 km from the summit vent, and 2–4 cm lithic lapilli reached the coastline, 17 km from the vent. The Episode 2 deposit is chemically zoned, indicating orderly eruption from a layered magma body analogous to the 1959 Kīlauea Iki lava lake. Olivine-hosted melt inclusions suggest a magma body within 1 km of the surface. Some Episode 1 lithic clasts have magmatic rinds chemically similar to the early Episode 2 scoria, suggesting a genetic link, although each had a distinct eruption mechanism. Southeastward tephra dispersal counter to NE trade winds implies dispersal by jet-stream winds. The dispersal of lithic clasts in Episode 1 cannot be explained by ballistic trajectories or by transport in a buoyant plume. Calculations instead indicate that a jet from a vent with a minimum diameter of 50 m, a velocity of at least 300 m/s, and a duration of ∼60 s could have lifted the lithic clasts into the jet stream. Isopach and isopleth maps for Episode 2 indicate a subplinian column height of 14–18 km and a duration of 2–3 h, assuming constant flux. The Episode 1 conduit probably intersected or otherwise lowered pressure within a compositionally zoned magma body, triggering eruption of the Episode 2 scoria.

Hawaii↗
USGS1994

Seawater as the source of minor elements in black shales, phosphorites and other sedimentary rocks

Many of the minor elements in seawater today have a concentration-depth profile similar to that of the biologically essential nutrients, NO-3 and PO3-4. They show a relative depletion in the photic zone and enrichment in the deep ocean. The difference between their surface- and deep-ocean values, normalized to the change in PO3-4, approaches the average of measured minor-element: P ratios in marine plankton, although individual analyses of the latter show extreme scatter for a variety of reasons. Despite this scatter in the minor-element analyses of plankton, agreement between the two sets of data shows unequivocally that an important marine flux of many minor elements through the ocean is in the form of biogenic matter, with a composition approaching that of plankton. This interpretation is further supported by sediment studies, particularly of sediments which accumulate in shelf-slope environments where biological productivity in the photic zone is exceptionally high and organic carbon contents of the underlying sediment elevated. The interelement relations observed for some of these sediments approach the average values of plankton. These same interelement relations are observed in many marine sedimentary rocks such as metalliferous black shales and phosphorites, rocks which have a high content of marine fractions (e.g., organic matter, apatite, biogenic silica and carbonates). Many previous studies of the geochemistry of these rocks have concluded that local hydrothermal activity, and/or seawater with an elemental content different from that of the modern ocean, was required to account for their minor-element contents. However, the similarity in several of the minor-element ratios in many of these formations to minor-element ratios in modern plankton demonstrates that these sedimentary rocks accumulated in environments whose marine chemistry was virtually identical to that seen on continental shelf-slopes, or in marginal seas, of the ocean today. The accumulation of the marine fraction of minor elements on these ancient sea floors was determined largely by the accumulation of organic matter, settling from the photic zone and with a composition of average plankton. A second marine fraction of minor elements in these rocks accumulated through precipitation and adsorption from seawater. The suite of elements in this fraction reflects redox conditions in the bottom water, as determined by bacterial respiration. For example, high Mn, high Cr+V and high Mo concentrations, above those which can be attributed to the accumulation of planktonic matter, characterize accumulation under bottom-water oxidizing, denitrifying and sulfate-reducing conditions, respectively. ?? 1994.

Chemical Geology↗
USGS1967

Shock effects in certain rock-forming minerals

Shock effects in quartz, plagioclase, biotite, amphibole, and some accessory minerals have been observed in rocks subjected to various degrees of meta morphism by meteoritic impact. The shock features described are unique; they are never observed in rocks from normal geologic environments. Such features are described: 1) Multiple sets of closely spaced planar microstructures occur in quartz, plagioclase, and other rock-forming minerals. Those characteristic of shock consist of alternating platelets, with a range of reduced mean index of re fraction and birefringence; they con sist of platelets that have been partially or completely transformed to an amor phous phase. 2) Quartz and plagioclase are selec tively and completely transformed to silica glass and plagioclase glass in the solid state, whereas the associated mafic minerals remained crystalline. There is no reaction between adjacent minerals. 3) High-pressure polymorphs occur, such as coesite or stishovite. Coesite oc Curs exclusively within silica glass; it has not been observed as a reaction or breakdown product. 4) Nickel-iron spherules occur in the fused glass or impactites. 5) The occurrence of droplets of ilmenite, rutile, pseudobrookite, and baddaleyite in impactites indicates a temperature of formation exceeding 150°C. 6) Dense glass occurs, similar in composition to bulk rock, in which iron oxide, such as fine particles of mag netite, is completely dissolved. All these features are characteristic of a process involving the rapid rise and fall of extremiiely high pressures and temperatures. Minerals and mineral as semblages experiencing such high strain rates and sudden changes of pressures and temperatures react and change in dependently to the bulk chemical com position, under nonequilibrium condi tions. Many aspects of shock features re quire careful study. Kink bands in biotite and deformation lamellae in quartz occur in tectonically deformed rocks. These features should be studied with great care in order to determine whether reduction in mean index of refraction and total birefringence along the planar structures have resulted from vitrification or phase transition; their presence is additional evidence in favor of a shock mechanism. Vitreous phases or glasses formed by shock also have many unique prop erties; they have not been studied by such methods as thermoluminescence, electron spin resonance, low-angle x ray diffraction, or infrared spectroscopy. Shock-fused glass of high density needs to be studied in detail in carefully con trolled laboratory conditions. Experimental shock-wave studies of the equation-of-state of single minerals and mineral assemblages, under care fully controlled conditions, must pre cede estimates of peak pressures and peak and residual temperatures of shocked natural mineral assemblages. Detailed petrographic and mineralogic studies, however, have provided useful and definitive criteria for characteriza tion of impact events. Such data should be of paramount importance in the study of samples brought back from Moon.

Science↗
USGS2005

Hydrogeologic framework, ground-water quality, and simulation of ground-water flow at the Fair Lawn Well Field Superfund site, Bergen County, New Jersey

Production wells in the Westmoreland well field, Fair Lawn, Bergen County, New Jersey (the 'Fair Lawn well field Superfund site'), are contaminated with volatile organic compounds, particularly trichloroethylene, tetrachloroethylene, and 1,1,1-trichloroethane. In 1983, the U.S. Environmental Protection Agency (USEPA) placed the Westmoreland well field on its National Priority List of Superfund sites. In an effort to determine ground-water flow directions, contaminant-plume boundaries, and contributing areas to production wells in Fair Lawn, and to evaluate the effect of present pump-and-treat systems on flowpaths of contaminated ground water, the U.S. Geological Survey (USGS), in cooperation with the USEPA, developed a conceptual hydrogeologic framework and ground-water flow model of the study area. MODFLOW-2000, the USGS three-dimensional finite-difference model, was used to delineate contributing areas to production wells in Fair Lawn and to compute flowpaths of contaminated ground water from three potential contaminant sources to the Westmoreland well field. Straddle-packer tests were used to determine the hydrologic framework of, distribution of contaminants in, and hydrologic properties of water-bearing and confining units that make up the fractured-rock aquifer underlying the study area. The study area consists of about 15 square miles in and near Fair Lawn. The area is underlain by 6 to 100 feet of glacial deposits and alluvium that, in turn, are underlain by the Passaic Formation. In the study area, the Passaic Formation consists of brownish-red pebble conglomerate, medium- to coarse-grained feldspathic sandstone, and micaceous siltstone. The bedrock strata strike N. 9o E. and dip 6.5o to the northwest. The bedrock consists of alternating layers of densely fractured rocks and sparsely fractured rocks, forming a fractured-rock aquifer. Ground-water flow in the fractured-rock aquifer is anisotropic as a result of the interlayering of dipping water-bearing and confining units. Wells of similar depth aligned along the strike of the bedding intersect the same water-bearing units, but wells aligned along the dip of the bedding may intersect different water-bearing units. Consequently, wells aligned along strike are in greater hydraulic connection than wells aligned along dip. The Borough of Fair Lawn pumps approximately 770 million gallons per year from 13 production wells. Hydrographs from six observation wells ranging in depth from 162 to 505 feet in Fair Lawn show that water levels in much of the study area are affected by pumping. Straddle packers were used to isolate discrete intervals within six open-hole observation wells owned by the Fair Lawn Water Department. Transmissivity, water-quality, and static-water-level data were obtained from the isolated intervals. Measured transmissivity ranged from near 0 to 8,900 feet squared per day. The broad range in measured transmissivity is a result of the heterogeneity of the fractured-rock aquifer. Eight water-bearing units and eight confining units were identified in the study area on the basis of transmissivity. The water-bearing units range in thickness from 21 to 95 feet; the mean thickness is 50 feet. The confining units range in thickness from 22 to 248 feet; the mean thickness is 83 feet. Water-level and water-quality data indicate effective separation of water-bearing units by the confining units. Water-quality samples were collected from the six observation wells at 16 depth intervals isolated by the straddle packers in 2000 and 2001. Concentrations of volatile organic compounds generally were low in samples from four of the wells, but were higher in samples from a well in Fair Lawn Industrial Park and in a well in the Westmoreland well field. The digital ground-water flow model was used to simulate steady-state scenarios representing conditions in the study area in 1991 and 2000. These years were chosen because during the intervening period,

Scientific Investigations Report↗
USGS2003

Potential for deep basin-centered gas accumulation in Travis Peak (Hosston) Formation, Gulf Coast Basin, U.S.A.

The potential of Lower Cretaceous sandstones of the Travis Peak Formation in the northern Gulf Coast Basin to harbor a basin-centered gas accumulation was evaluated by examining (1) the depositional and diagenetic history and reservoir properties of Travis Peak sandstones, (2) the presence and quality of source rocks for generating gas, (3) the burial and thermal history of source rocks and time of gas generation and migration relative to tectonic development of Travis Peak traps, (4) gas and water recoveries from drill-stem and formation tests, (5) the distribution of abnormal pressures based on shut-in-pressure data, and (6) the presence or absence of gas-water contacts associated with gas accumulations in Travis Peak sandstones. The Travis Peak Formation (and correlative Hosston Formation) is a basinward-thickening wedge of terrigenous clastic sedimentary rocks that underlies the northern Gulf Coast Basin from eastern Texas across northern Louisiana to southern Mississippi. Clastic influx was focused in two main fluvial-deltaic depocenters—one located in northeastern Texas and the other in southeastern Mississippi and northeastern Louisiana. Across the main hydrocarbon-productive trend in eastern Texas and northern Louisiana, the Travis Peak Formation is about 2,000 ft thick. Most Travis Peak hydrocarbon production in eastern Texas comes from drilling depths between 6,000 and 10,000 ft. Significant decrease in porosity and permeability occurs through that depth interval. Above 8,000-ft drilling depth in eastern Texas, Travis Peak sandstone matrix permeabilities often are significantly higher than the 0.1-millidarcy (mD) cutoff that characterizes tight-gas reservoirs. Below 8,000 ft, matrix permeability of Travis Peak sandstones is low because of pervasive quartz cementation, but abundant natural fractures impart significant fracture permeability. Although pressure data within the middle and lower Travis Peak Formation are limited in eastern Texas, overpressured reservoirs caused by thermal generation of gas, typical of basin-centered gas accumulations, are not common in the Travis Peak Formation. Significant overpressure was found in only one Travis Peak sandstone reservoir in 1 of 24 oil and gas fields examined across eastern Texas and northern Louisiana. The presence of gas-water contacts is perhaps the most definitive criterion indicating that a gas accumulation is conventional rather than a “sweet spot” within a basin-centered gas accumulation. Hydrocarbon-water contacts within Travis Peak sandstone reservoirs were documented in 17 fields and probably occur in considerably more fields across the productive Travis Peak trend in eastern Texas and northern Louisiana. All known hydrocarbon-water contacts in Travis Peak reservoirs in eastern Texas, however, occur within sandstones in the upper 500 ft of the formation. Although no gas-water contacts have been reported within the lower three-fourths of the Travis Peak Formation in northeastern Texas, gas production from that interval is limited. The best available data suggest that most middle and lower Travis Peak sandstones are water bearing in northeastern Texas. Insufficient hydrocarbon charge relative to permeability of Travis Peak reservoirs might be responsible for lack of overpressure and basin-centered gas within the Travis Peak Formation. Shales interbedded with Travis Peak sandstones in eastern Texas are primarily oxidized flood-plain deposits with insufficient organic-carbon content to be significant sources of oil and gas. The most likely source rocks for hydrocarbons in Travis Peak reservoirs are two stratigraphically lower units, the Jurassic-age Bossier Shale of the Cotton Valley Group, and laminated, lime mudstones of the Jurassic Smackover Formation. Hydrocarbon charge, therefore, might be sufficient for development of conventional gas accumulations, but it is insufficient for development of basin-centered gas as a result of the absence of proximal source rocks and a lack of effective migration pathways from stratigraphically or geographically distant source rocks.

Louisiana, Mississippi, Texas↗
USGS1967

Ground water in the Eola-Amity Hills area, northern Willamette Valley, Oregon

The Eola-Amity Hills area ,comprises about 230 square miles on the west side of the Willamette Valley between Salem and McMinnville, Oreg. The area is largely rural, and agriculture is the principal occupation. Rocks ranging in age from Eocene to Recent underlie the area. The oldest rocks are a sequence more than 5,000 feet thick of marine-deposited shale and siltstone strata, with thin interbeds of sandstone that range in age from Eocene to middle Oligocene. They are widely exposed in and west of the Eola-Amity Hills and underlie younger sedimentary and volcanic rocks throughout the study area. In the Eola-Amity Hills and Red Hills of Dundee, the Columbia River Group, a series of eastward-dipping basaltic lava flows locally of Miocene age, and conformably overlies the marine sedimentary rocks. The Columbia River Group ranges in thickness from less than 1 foot to about 900 feet and has an average thickness of about 200 feet. The formation is exposed in the Eola-Amity Hills and Red Hills of Dundee and, at places, extends to the east beneath younger rocks. Overlying the Columbia River Group and marine sedimentary rocks are nonmarine sedimentary deposits that range in thickness from less than 1 foot, where they lap up (to an altitude of about 200 ft) on the flanks of the higher hills, to several hundred feet along the east margin of the study area. These deposits include the Troutdale Formation of Pliocene age, the Willamette Silt of late Pleistocene age, and alluvium of the Willamette River and its tributaries. The Troutdale Formation and the alluvium of the Willamette River contain the most productive aquifers in the Eola-Amity Hills area. These aquifers, which consist mainly of sand and gravel, generally yield moderate to large quantities of water to properly constructed wells. Basalt of the Columbia River Group yields small to moderate quantities of water to wells, and the marine sedimentary rocks and Willamette Silt generally yield small but adequate quantities of water for domestic and stock supplies. Ground water from the Columbia River Group and nonmarine sedimentary rocks is chemically suitable for irrigation and other uses, as is the water from shallow depths in the marine sedimentary rocks. However, water from depths of more than several hundred feet in the marine sedimentary rocks contains large amounts of chloride and other dissolved mineral constitutents that make it unsuitable for most uses. Samples from three fairly closely spaced wells obtaining water from depth zones of 50 to 77, 191 to 201, and about 2,000 feet contained 172, 1,160, and 26,000 ppm (parts per million) of chloride, respectively. About 6,100 acre-feet of ground water was pumped from wells and withdrawn from springs for various uses during 1964; of this amount about 4,800 acre-feet was used for irrigation. The total volume of ground water withdrawn and put to beneficial use each year is small compared with the amount that discharges naturally by evapotranspiration and through undeveloped seeps and springs. Much of the natural discharge could be intercepted and put to beneficial use by pumping from wells. Major problems affecting the development of ground water in the area include a) uneven areal distribution of permeable rocks, (b) undesirable chemical quality of the ground water locally in the marine sedimentary rocks, and (c) fine sand entering wells that tap the Troutdale Formation and thereby causing loss of well efficiency and costly wear on pumps and water-supply systems.

Water Supply Paper↗
USGS2004

Preliminary geologic map of the Big Bear City 7.5' Quadrangle, San Bernardino County, California

This data set maps and describes the geology of the Big Bear City 7.5' quadrangle, San Bernardino County, California. Created using Environmental Systems Research Institute's ARC/INFO software, the data base consists of the following items: (1) a rock-unit coverage and attribute tables (polygon and arc) containing geologic contacts, units and rock-unit labels as annotation which are also included in a separate annotation coverage, bbc_anno (2) a point coverage containing structural point data and (3) a coverage containing fold axes. In addition, the data set includes the following graphic and text products: (1) A PostScript graphic plot-file containing the geologic map, topography, cultural data, a Correlation of Map Units (CMU) diagram, a Description of Map Units (DMU), an index map, a regional geologic and structure map, and an explanation for point and line symbols; (2) PDF files of the Readme (including the metadata file as an appendix), and a screen graphic of the plot produced by the PostScript plot file. The geologic map describes a geologically complex area on the north side of the San Bernardino Mountains. Bedrock units in the Big Bear City quadrangle are dominated by (1) large Cretaceous granitic bodies ranging in composition from monzogranite to gabbro, (2) metamorphosed sedimentary rocks ranging in age from late Paleozoic to late Proterozoic, and (3) Middle Proterozoic gneiss. These rocks are complexly deformed by normal, reverse, and thrust faults, and in places are tightly folded. The geologic map database contains original U.S. Geological Survey data generated by detailed field observation and by interpretation of aerial photographs. The map data was compiled on base-stable cronoflex copies of the Big Bear City 7.5' topographic map, transferred to a scribe-guide and subsequently digitized. Lines, points, and polygons were edited at the USGS using standard ARC/INFO commands. Digitizing and editing artifacts significant enough to display at a scale of 1:24,000 were corrected. Within the database, geologic contacts are represented as lines (arcs), geologic units as polygons, and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify each geologic datum.

Open-File Report↗