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At least 847 records · Page 47Linked to original sources
USGS1998

Non-water-ice constituents in the surface material of the icy Galilean satellites from the Galileo near-infrared mapping spectrometer investigation

We present evidence for several non‐ice constituents in the surface material of the icy Galilean satellites, using the reflectance spectra returned by the Galileo near infrared mapping spectrometer (NIMS) experiment. Five new absorption features are described at 3.4, 3.88, 4.05, 4.25, and 4.57 μm for Callisto and Ganymede, and some seem to exist for Europa as well. The four absorption bands strong enough to be mapped on Callisto and Ganymede are each spatially distributed in different ways, indicating different materials are responsible for each absorption. The spatial distributions are correlated at the local level in complex ways with surface features and in some cases show global patterns. Suggested candidate spectrally active groups, perhaps within larger molecules, producing the five absorptions include C‐H, S‐H, SO 2 , CO 2 , and C≡N. Organic material like tholins are candidates for the 4.57‐ and 3.4‐μm features. We suggest, based on spectroscopic evidence, that CO 2 is present as a form which does not allow rotational modes and that SO 2 is present neither as a frost nor a free gas. The CO 2 , SO 2 , and perhaps cyanogen (4.57 μm) may be present as very small collections of molecules within the crystal structure, perhaps following models for radiation damage and/or for comet and interstellar grain formation at low temperatures. Some of the dark material on these surfaces may be created by radiation damage of the CO 2 and other carbon‐bearing species and the formation of graphite. These spectra suggest a complex chemistry within the surface materials and an important role for non‐ice materials in the evolution of the satellite surfaces.

Journal of Geophysical Research E: Planets↗
USGS2012

Mineralogy and geochemistry of a sediment‐hosted hydrothermal sulfide deposit from the Southern Trough of Guaymas Basin, Gulf of California

Samples dredged from a 15‐m‐high hydrothermal mound atop the flat turbidite pond in the Southern Trough of Guaymas Basin consist of pyrrhotite‐rich massive sulfide, barite, barite + calcite, talc, and opaline silica as well as substrate material composed of fossiliferous, clay‐rich ooze. An 11‐m‐long sediment core taken near the dredge site shows increasing hydrothermal alteration with depth; anhydrite‐filled fractures near the base of the core appear to be channels for hydrothermal discharge. Oxidation of the sulfide‐rich samples to an assemblage of geothite, lepidocrocite, and amorphous Fe oxyhydroxide is ubiquitous. Compared to other massive sulfide deposits on sediment‐starved oceanic ridges, the hydrothermal deposit dredged in Guaymas Basin has a high pyrrhotite/pyrite ratio, a low Zn sulfide and combined ore metal (Cu + Zn + Pb + Ag + Cd) content, and a greater abundance of sulfate, carbonate, and silicate phases. Venting hydrothermal solutions are alkaline with moderately high p H; high Ca, Ba, and SiO 2 content; low ƒS 2 and ƒo 2 ; and very low transition metal content. Disequilibrium assemblages of pyrrhotite and sulfate minerals form during rapid mixing of this evolved vent fluid with ambient bottom waters at the discharge site. Talc is formed at a temperature near 270°C by mixing or entrainment of Mg‐rich bottom water or pore fluid with upwelling hydrothermal fluid that is saturated with silica. Calcite may precipitate from the alkaline, Ca‐rich fluid during degassing of CO 2 . The minimum temperature range for sulfide and nonsulfide deposition is approximately 190°–326°C. The composition of hydrothermal deposits, vent solutions, and altered sediment requires that circulating fluids evolve during deep penetration into the basaltic basement complex, further interaction with the organic‐and carbonate‐rich sediment pile, and near‐surface mixing with ambient seawater. Although the stable assemblage albite‐epidote‐clinochlore present at depth in the sediment pile requires very low dissolved Mg and Fe in the altering fluid, the addition of Mg to deeply buried sediment indicates significant recharge of the system by Guaymas Basin bottom water.

Southern Trough of Guaymas Basin↗
USGS2009

Use of airborne and terrestrial lidar to detect ground displacement hazards to water systems

We investigate the use of multiepoch airborne and terrestrial lidar to detect and measure ground displacements of sufficient magnitude to damage buried pipelines and other water system facilities that might result, for example, from earthquake or rainfall-induced landslides. Lidar scans are performed at three sites with coincident measurements by total station surveying. Relative horizontal accuracy is evaluated by measurements of lateral dimensions of well defined objects such as buildings and tanks; we find misfits ranging from approximately 5 to 12 cm, which is consistent with previous work. The bias and dispersion of lidar elevation measurements, relative to total station surveying, is assessed at two sites: (1) a power plant site (PP2) with vegetated steeply sloping terrain; and (2) a relatively flat and unvegetated site before and after trenching operations were performed. At PP2, airborne lidar showed minimal elevation bias and a standard deviation of approximately 70 cm, whereas terrestrial lidar did not produce useful results due to beam divergence issues and inadequate sampling of the study region. At the trench site, airborne lidar showed minimal elevation bias and reduced standard deviation relative to PP2 (6-20 cm), whereas terrestrial lidar was nearly unbiased with very low dispersion (4-6 cm). Pre- and posttrench bias-adjusted normalized residuals showed minimal to negligible correlation, but elevation change was affected by relative bias between epochs. The mean of elevation change bias essentially matches the difference in means of pre- and posttrench elevation bias, whereas elevation change standard deviation is sensitive to the dispersion of individual epoch elevations and their correlation coefficient. The observed lidar bias and standard deviations enable reliable detection of damaging ground displacements for some pipelines types (e.g., welded steel) but not all (e.g., concrete with unwelded, mortared joints). ?? ASCE 2009.

Journal of Surveying Engineering↗
USGS1996

Interannual climate variability and snowpack in the western United States

An important part of the water supply in the western United States is derived from runoff fed by mountain snowmelt Snow accumulation responds to both precipitation and temperature variations, and forms an interesting climatic index, since it integrates these influences over the entire late fall-spring period. Here, effects of cool season climate variability upon snow water equivalent (SWE) over the western part of the conterminous United States are examined. The focus is on measurements on/and 1 April, when snow accumulation is typically greatest. The primary data, from a network of mountainous snow courses, provides a good description of interannual fluctuations in snow accumulations, since many snow courses have records of five decades or more. For any given year, the spring SWE anomaly at a particular snow course is likely to be 25%–60% of its long-term average. Five separate regions of anomalous SWE variability are distinguished, using a rotated principal components analysis. Although effects vary with region and with elevation, in general, the anomalous winter precipitation has the strongest influence on spring SWE fluctuations. Anomalous temperature has a weaker effect overall, but it has great influence in lower elevations such as in the coastal Northwest, and during spring in higher elevations. The regional snow anomaly patterns are associated with precipitation and temperature anomalies in winter and early spring. Patterns of the precipitation, temperature, and snow anomalies extend over broad regional areas, much larger than individual watersheds. These surface anomalies are organized by the atmospheric circulation, with primary anomaly centers over the North Pacific Ocean as well as over western North America. For most of the regions, anomalously low SWE is associated with a winter circulation resembling the PNA pattern. With a strong low in the central North Pacific and high pressure over the Pacific Northwest, this pattern diverts North Pacific storms northward, away from the region. Both warm and cool phases of El Niño-Southern Oscillation tend to produce regional patterns with out-of-phase SWE anomalies in the Northwest and the Southwest.

Arizona, California, Colorado, Idaho, Montana, Nev↗
USGS1995

Intraglacial volcanism in the Wells Gray–Clearwater volcanic field, east-central British Columbia, Canada

Small-volume, subaerial, subaqueous and subglacial basaltic eruptions occurred in the Wells Gray–Clearwater area during Quaternary time. Part of this time, significant thicknesses of glacial ice were present. Dating of intraglacial volcanic features corroborates other evidence of an Early Pleistocene, Cordilleran-wide ice sheet. Of the intraglacial volcanoes investigated, three were studied in detail and of these, two probably erupted during the Fraser glaciation (11–20 ka), when maximum ice level exceeded 2100 m elevation. Major-element and sulphur concentrations were measured in glass from the volcanoes to provide insight into vent conditions at the time of eruption. Hyalo Ridge (2102 m elevation, whole-rock K–Ar age of 0.02 ± 0.01 Ma) is a small volcanic edifice capped by lava flows with coherent pillowed lavas and interbedded hyaloclastite exposed over nearly 400 m altitude on its east flank. Low sulphur content (<0.03 wt.%) in pillow rim glasses indicates that the lavas are degassed. It is interpreted that the vent built above the water (or ice) surface then fed lava flows that crossed a shoreline and produced pillowed flows. Pyramid Mountain is a volcanic cone 240 m high, comprised of glassy, vesicular, lapilli-tuff breccia. The highly alkalic glass contains 0.1 wt.% S (considered high), and indicates a high original volatile content and drastic quenching, probably during phreatomagmatic eruption from a meltwater-flooded vent. East of the Clearwater River a sequence of massive pillowed flows and pillow joint-block breccias is exposed from 880 to 1320 m elevation (0.27 ± 0.05 Ma). The vent location is unknown. Moderate S content (0.040–0.055 wt.%) indicates that the lavas were erupted in shallow water and are largely degassed. The S content of glass in dykes cutting the pillow breccias is low. The dykes are interpreted as lava that has flowed laterally or down into cracks

British Columbia↗
USGS2023

Four decades of regional wet deposition, local bulk deposition, and stream-water chemistry show the influence of nearby land use on forested streams in Central Appalachia☆

Hydrologic monitoring began on two headwater streams (<1 km 2 ) on the University of Kentucky's Robinson Forest in 1971. We evaluated stream-water (1974–2013) and bulk-deposition (wet + dust) (1984–2013) chemistry in the context of regional wet-deposition patterns that showed decreases in both sulfate and nitrate concentrations as well as proximal surface-mine expansion. Decadal time steps (1974–83, 1984–93, 1994–2003, 2004–2013) were used to quantify change. Comparison of the first two decades showed similarly decreased sulfate (minimum flow-adjusted annual-mean concentration of ≈13.5 mg/L in 1982 to 8.8 mg/L in 1992) and increased pH (6.6–6.8) in both streams, reflecting contemporaneous changes in both bulk and wet deposition. In contrast, concentrations of nitrate (0.14 to >0.25 mg/L) and base cations increased between these two decades, coinciding with expansion of surface mining between 1985 and 1995. In 2004, stream-water pH (6.7 in 2004), sulfate (9.2 mg/L), and nitrate (>0.11 mg/L) were similar to 1982, despite wet-deposition concentrations being lower. Base-cation concentrations were higher in the stream adjacent to ongoing surface mining relative to the stream situated near the middle of the experimental forest. However, pH decreased to approximately 5.7 by 2013 for both streams, which, combined with a shift in dominant cations from calcium to magnesium and potassium, indicates that the soil-buffering capacity of this landscape has been exceeded. Ratios of bulk deposition and stream-water concentrations indicate enrichment of sulfate (1.7–25.2) and cations (0.5–64.8), but not nitrogen (0.1–5.6), indicating that the Forest is not nitrogen saturated and that ongoing changes in water-quality are sulfate driven. When concentrations were adjusted to account for changes in streamflow (climate) over the 4 decades, external influences (land management/regulation) explained most change. The amount and direction of change differed among constituents, both between consecutive decades and between the first and last decades, reflecting the influence of localized surface mining even as regional wet deposition continued to improve due to the Clean Air Act. The implication is that localized stressors have the potential to out-pace the benefits of national environmental policies for communities that depend on local water-resources in similar environments.

Kentucky↗
USGS2012

Permeability of fault gouge under confining pressure and shear stress

The permeability of both clay-rich and non-clay gouges, as well as several pure clays, was studied as a function of confining pressures from 5 to 200 MPa and shear strain to 10. Permeability ranged over four orders of magnitude, from around 10 −22 to 10 −18 m 2 (1 darcy = 0.987 × 10 −12 m 2 ). The lowest values were characteristic of the montmorillonite-rich and finer grained non-clay gouges. Illite, kaolinite, and chlorite had intermediate permeabilities, while the highest values were typical of the serpentine and coarser grained non-clay gouges. Grain size was an important factor in determining permeability, particularly for the clay-rich samples. The coarse grained gouges were the most permeable and decreased in permeability after shearing. Conversely, the fine grained gouges had characteristically lower permeabilities that did not vary significantly after various amounts of shearing. The permeabilities of the non-clay samples were not significantly different than those of the clays. Therefore, comminuted rock flours can be equally as effective in reducing the flow of water as the characteristically low permeability clay gouges. The strengths of the samples were quite variable. The non-clay gouges were consistently the strongest, with yield points (beginning of nonelastic behavior) around 850 MPa, while montmorillonite had an anomalously low strength in relation to all the other gouges at 250 MPa. Strength of the saturated samples under drained (low pore pressure) conditions did not correlate with high or low permeability. However, the low permeabilities of these gouges could be a factor in the measured low shear stresses along fault regions if excess pore pressures were created as a result of shearing or compaction, and this pressure was unable to dissipate through a thick section of the material.

Journal of Geophysical Research Solid Earth↗
USGS1975

Silurian and Devonian miogeosynclinal and transitional rocks of the Fish Creek Reservoir window, central Idaho

Documentation of Devonian continental-shelf shallow-water carbonate rocks in the core of the Fish Creek Reservoir window shifts the known westernmost limit of the Devonian miogeosyncline 50 km (30 mi) southwest across the structural grain from the well-known miogeosynclinal sequence in the Lost River Range. The miogeosynclinal carbonate sequence in the window has a minimum thickness of 450 m (1,500 ft). It comprises the upper Lower Devonian (Emsian) and lower Middle Devonian (Eifelian) Carey Dolomite (new), the upper Middle Devonian (Givetian) and Upper Devonian Jefferson Formation, and the Upper Devonian Picabo Formation (new). Conodont faunas precisely date the Carey. The Picabo Formation, composed of interbedded sandy dolomite-pebble conglomerate and dolomitic quartzose sandstone, is unlike any previously described formation of Late Devonian or Early Mississippian age in central Idaho. It resembles parts of the Stansbury, Beirdneau, Leatham, and Victoria Formations, which reflect areas of local Late Devonian uplift and erosion of older shelf rocks in northern Utah and southeastern Idaho. Transitional (continental-slope) rocks of the Roberts Mountains Formation representing reef and offreef facies are thrust over the Devonian shelf sequence within the Fish Creek Reservoir window. The Roberts Mountains Formation here is precisely dated as latest Silurian (Pridolian, eosteinhornensis Zone) through earliest Devonian (Lochkovian) by a sequence of conodont faunas. The easternmost known exposures of possible Devonian siliceous facies rocks assigned to the Milligen(?) Formation are present less than 4.8 km (3 mi) southwest of the shelf sequence. Structural relations and paleotectonic reconstructions suggest that they have a minimum eastward translation of 32 km (20 mi). The Devonian continent-ocean basin interface, along which the Antler orogenic belt developed at this latitude, probably was located near the east edge of the present Idaho batholith.

Idaho↗
USGS2005

Spatiotemporal patterns in community structure of macroinvertebrates inhabiting calcareous periphyton mats

Calcareous floating periphyton mats in the southern Everglades provide habitat for a diverse macroinvertebrate community that has not been well characterized. Our study described this community in an oligotrophic marsh, compared it with the macroinvertebrate community associated with adjacent epiphytic algae attached to macrophytes in the water column, and detected spatial patterns in density and community structure. The floating periphyton mat (floating mat) and epiphytic algae in the water column (submerged epiphyton) were sampled at 4 sites (???1 km apart) in northern Shark River Slough, Everglades National Park (ENP), in the early (July) and late (November) wet season. Two perpendicular 90-m transects were established at each site and ???100 samples were taken in a nested design. Sites were located in wet-prairie spikerush-dominated sloughs with similar water depths and emergent macrophyte communities. Floating mats were sampled by taking cores (6-cm diameter) that were sorted under magnification to enumerate infauna retained on a 250-??m-mesh sieve and with a maximum dimension >1 mm. Our results showed that floating mats provide habitat for a macroinvertebrate community with higher densities (no. animals/g ash-free dry mass) of Hyalella azteca, Dasyhelea spp., and Cladocera, and lower densities of Chironomidae and Planorbella spp. than communities associated with submerged epiphyton. Densities of the most common taxa increased 3x to 15x from early to late wet season, and community differences between the 2 habitat types became more pronounced. Floating-mat coverage and estimated floating-mat biomass increased 20 to 30%, and 30 to 110%, respectively, at most sites in the late wet season. Some intersite variation was observed in individual taxa, but no consistent spatial pattern in any taxon was detected at any scale (from 0.2 m to 3 km). Floating mats and their resident macroinvertebrate communities are important components in the Everglades food web. This community should be included in environmental monitoring programs because degradation and eventual loss of the calcareous periphyton mat is associated with P enrichment in this ecosystem. ?? 2005 by The North American Benthological Society.

Journal of the North American Benthological Societ↗
USGS2001

Modeling consolidation and dewatering near the toe of the northern Barbados accretionary complex

At the toe of the northern Barbados accretionary complex, temperature and pore water chemistry data indicate that fluid flow is channeled along the décollement and other shallow thrust faults. We examine mechanisms that may prevent consolidation and maintain high permeability over large sections of the décollement. High-resolution bulk density data from five boreholes show that the décollement is well consolidated at some sites while other sites remain underconsolidated. Underconsolidated décollement behavior is associated with kilometer-scale negative-polarity seismic reflections from the décollement plane that have been interpreted to be fluid conduits. We use a coupled fluid flow/consolidation model to simulate the loading response of a 10-km-long by 680-m-thick slice of sediment as it enters the accretionary complex. The simulations capture 185 ka (5 km) of subduction, with a load function representing the estimated effective stress of the overriding accretionary prism (3.8° taper angle). Simulation results of bulk density in the décollement 3.2 km arcward of the deformation front are compared with observations. The results show that persistent high pore pressures at the arcward edge of the simulation domain can explain underconsolidated behavior. The scenario is consistent with previous modeling results showing that high pore pressures can propagate intermittently along the décollement from deeper in the complex. Simulated seaward fluxes in the décollement (1–14 cm yr −1 ) lie between previous estimates from modeling studies of steady state (<1 cm yr −1 ) and transient (>1 m yr −1 ) flow. Maximum simulated instantaneous fluid sources (2.5×10 −13 s −1 ) are comparable to previous estimates. The simulations show minor swelling of incoming sediments (fluid sources ∼−3×10 −15 s −1 ) up to 3 km before subduction that may help to explain small-scale shearing and normal faulting proximal to the protodécollement.

Atlantic Ocean, Northern Barbados Accretionary Com↗
USGS2006

Recharge processes drive sulfate reduction in an alluvial aquifer contaminated with landfill leachate

Natural attenuation of contaminants in groundwater depends on an adequate supply of electron acceptors to stimulate biodegradation. In an alluvial aquifer contaminated with leachate from an unlined municipal landfill, the mechanism of recharge infiltration was investigated as a source of electron acceptors. Water samples were collected monthly at closely spaced intervals in the top 2 m of the saturated zone from a leachate-contaminated well and an uncontaminated well, and analyzed for δ 18 O, δ 2 H, non-volatile dissolved organic carbon (NVDOC), SO 4 2− , NO 3 − and Cl − . Monthly recharge amounts were quantified using the offset of the δ 18 O or δ 2 H from the local meteoric water line as a parameter to distinguish water types, as evaporation and methanogenesis caused isotopic enrichment in waters from different sources. Presence of dissolved SO 4 2− in the top 1 to 2 m of the saturated zone was associated with recharge; SO 4 2− averaged 2.2 mM, with maximum concentrations of 15 mM. Nitrate was observed near the water table at the contaminated site at concentrations up to 4.6 mM. Temporal monitoring of δ 2 H and SO 4 2− showed that vertical transport of recharge carried SO 4 2− to depths up to 1.75 m below the water table, supplying an additional electron acceptor to the predominantly methanogenic leachate plume. Measurements of δ 34 S in SO 4 2− indicated both SO 4 2− reduction and sulfide oxidation were occurring in the aquifer. Depth-integrated net SO 4 2− reduction rates, calculated using the natural Cl − gradient as a conservative tracer, ranged from 7.5 × 10 − 3 to 0.61 mM·d − 1 (over various depth intervals from 0.45 to 1.75 m). Sulfate reduction occurred at both the contaminated and uncontaminated sites; however, median SO 4 2− reduction rates were higher at the contaminated site. Although estimated SO 4 2− reduction rates are relatively high, significant decreases in NVDOC were not observed at the contaminated site. Organic compounds more labile than the leachate NVDOC may be present in the root zone, and SO 4 2− reduction may be coupled to methane oxidation. The results show that sulfur (and possibly nitrogen) redox processes within the top 2 m of the aquifer are directly related to recharge timing and seasonal water level changes in the aquifer. The results suggest that SO 4 2− reduction associated with the infiltration of recharge may be a significant factor affecting natural attenuation of contaminants in alluvial aquifers.

Journal of Contaminant Hydrology↗
USGS2016

Reconstructing surface ocean circulation with 129 I time series records from corals

The long-lived radionuclide 129 I (half-life: 15.7 × 10 6 yr) is well-known as a useful environmental tracer. At present, the global 129 I in surface water is about 1–2 orders of magnitude higher than pre-1960 levels. Since the 1990s, anthropogenic 129 I produced from industrial nuclear fuels reprocessing plants has been the primary source of 129 I in marine surface waters of the Atlantic and around the globe. Here we present four coral 129 I time series records from: 1) Con Dao and 2) Xisha Islands, the South China Sea, 3) Rabaul, Papua New Guinea and 4) Guam. The Con Dao coral 129 I record features a sudden increase in 129 I in 1959. The Xisha coral shows similar peak values for 129 I as the Con Dao coral, punctuated by distinct low values, likely due to the upwelling in the central South China Sea. The Rabaul coral features much more gradual 129 I increases in the 1970s, similar to a published record from the Solomon Islands. The Guam coral 129 I record contains the largest measured values for any site, with two large peaks, in 1955 and 1959. Nuclear weapons testing was the primary 129 I source in the Western Pacific in the latter part of the 20th Century, notably from testing in the Marshall Islands. The Guam 1955 peak and Con Dao 1959 increases are likely from the 1954 Castle Bravo test, and the Operation Hardtack I test is the most likely source of the 1959 peak observed at Guam. Radiogenic iodine found in coral was carried primarily through surface ocean currents. The coral 129 I time series data provide a broad picture of the surface distribution and depth penetration of 129 I in the Pacific Ocean over the past 60 years.

Journal of Environmental Radioactivity↗
USGS2011

Evaluation of offshore stocking of Lake Trout in Lake Ontario

Restoration stocking of hatchery-reared lake trout Salvelinus namaycush has occurred in Lake Ontario since 1973. In U.S. waters, fish stocked through 1990 survived well and built a large adult population. Survival of yearlings stocked from shore declined during 1990–1995, and adult numbers fell during 1998–2005. Offshore stocking of lake trout was initiated in the late 1990s in response to its successful mitigation of predation losses to double-crested cormorants Phalacrocorax auritus and the results of earlier studies that suggested it would enhance survival in some cases. The current study was designed to test the relative effectiveness of three stocking methods at a time when poststocking survival for lake trout was quite low and losses due to fish predators was a suspected factor. The stocking methods tested during 2000–2002 included May offshore, May onshore, and June onshore. Visual observations during nearshore stockings and hydroacoustic observations of offshore stockings indicated that release methods were not a direct cause of fish mortality. Experimental stockings were replicated for 3 years at one site in the southwest and for 2 years at one site in the southeast. Offshore releases used a landing craft to transport hatchery trucks from 3 to 6 km offshore out to 55–60-m-deep water. For the southwest site, offshore stocking significantly enhanced poststocking survival. Among the three methods, survival ratios were 1.74 : 1.00 : 1.02 (May offshore : May onshore : June onshore). Although not statistically significant owing to the small samples, the trends were similar for the southeast site, with survival ratios of 1.67 : 1.00 : 0.72. Consistent trends across years and sites indicated that offshore stocking of yearling lake trout during 2000–2002 provided nearly a twofold enhancement in survival; however, this increase does not appear to be great enough to achieve the 12-fold enhancement necessary to return population abundance to restoration targets.

North American Journal of Fisheries Management↗
USGS1919

The oil fields of Allen County, Kentucky, with notes on the oil geology of adjoining counties

This report is based on a reconnaissance investigation of the oil field of Allen County, Ky., which was part of a broader study of the oil and gas fields of Kentucky, Tennessee, and Alabama, on which a general report is planned. Most of the field work was done by Mr. Mather, who spent three and a half weeks in and around the county. Mr. Shaw visited Scottsville, the county seat of Allen County, a few years ago and spent a few days in that vicinity at the beginning of the recent field work, which extended from the middle of April to the middle of May, 1917 He prepared also the first draft of the report and reviewed the literature, including reports in oil and gas journals. The purpose of the field work was to investigate the geology of the county, particularly the structure or lay of the oil-bearing strata and the results of drilling to date. Structural conditions in the producing fields were determined by running level lines to the wells and correlating the data recorded in the well logs generously furnished by the operators. Traverses were made of outcrops, and observations of the dip and strike were made in different parts of the county. Lack of a topographic base map and of time and funds for making an accurate topographic survey render the results of the work somewhat incomplete, but it is hoped they will form a valuable contribution to the knowledge of the geology of this relatively little known region, for little detailed geologic work has been done heretofore within 50 miles of Scottsville. The dips are generally too low to be read by the clinometer, but in some localities unmistakable dips can be observed in extensive outcrops along creek banks and can be measured with a level or hand transit. Few of the beds of this region can be followed any considerable distance, though by means of fossils the stratigraphic position of beds outcropping many miles apart can be determined within a few feet. The black shale is the best horizon marker, but it outcrops in only a few places and is reached in only a few wells outside the oil fields. The field work thus consisted largely in observations on out- , cropping beds in different localities and in estimating the altitude of those identified, in collecting fossils for use in future detailed work, and in obtaining from oil operators data concerning the wells and their output. It included the determination of the general lay of the rocks in the county and surrounding territory and details of structure in certain areas. The rocks lie so nearly flat that without topographic data only the general dip could be made out for a large part of the area examined. A complete set of logs of wildcat wells in the region would have thrown much light on the structure and oil possibilities, but little is known of many of the earlier wells drilled in the region, especially of those altogether unsuccessful. An unsuccessful test is soon forgotten, though the data thus obtained concerning the depth at which different beds were found and the yield of porous strata, whether water, oil, or gas, is of great value to the geologist and oil prospector.

Kentucky↗
USGS2008

Sources and fate of nitrate in the Illinois River Basin, Illinois

We conducted a two-year investigation into the sources and fate of nitrate (NO3-) in the Illinois River from the Chicago area to the river's confluence with the Mississippi River. Samples from waterways in the Chicago area (Des Plaines River and the Sanitary and Ship Canal) had relatively high concentrations of nitrogen (N) species and NO3- isotopic compositions indicative of treated wastewater (TWW). Downstream of the Brandon Road Lock and Dam, NO3- in tributaries discharging to the Illinois River primarily comes from tiles draining row crops. Nitrate isotopic signatures from these tributaries as well as drain tiles were indicative of synthetic fertilizer and/or soil organic matter (SOM) at various stages of denitrification. Nitrate-N concentrations generally decreased in the Illinois River with distance from the Chicago area primarily due to dilution. The decrease in NO3-N concentrations was especially conspicuous during the summer, when there is minimal discharge from drain tiles and NO3-N concentrations in the tributaries were low. In August 2005, when conditions were very dry, NO3-N concentrations decreased from 7.4 mg/L in the Chicago area to less than 1 mg/L near where the Illinois River discharges to the Mississippi River. The isotopic composition of NO3- in water samples from the Illinois River were a mixture of three end members: (1) fertilizer and/or SOM in drain tile water, typically showing the least amount of denitrification, (2) fertilizer and/or SOM in deeper ground water, showing the highest degree of denitrification, and (3) TWW. There was seasonal variability, depending on the volume of water flowing in the Illinois River. During high flow periods, river water samples plotted closest to those of tile drain samples; during low flow periods, a greater influence of TWW was observed in the isotopic composition. A subset of summer samples from the Chicago waterways had isotopic values plotting near and within the domain that characterizes manure and sewage. Nitrate in the Chicago area is primarily derived from TWW, with its isotopic signature evident downstream at least as far as Pekin during most of the year and all the way to the Mississippi River during periods of low flow. Denitrification occurs predominantly in groundwater between and away from drain tiles, although there is evidence that in-stream denitrification and/or biological uptake of NO3- occurs in the Peoria Lake reach of the Illinois River, at least during periods of low flow in the summer. We calculated that the river was losing about half of its NO3-N load in Peoria Lake in August 2005 (a period of very low flow), at a rate of about 7500 kg/day.

Journal of Hydrology↗
USGS2006

Multiple edifice-collapse events in the Eastern Mexican Volcanic Belt: The role of sloping substrate and implications for hazard assessment

The Citlalte??petl-Cofre de Perote volcanic chain forms an important physiographic barrier that separates the Central Altiplano (2500??masl) from the Gulf Coastal Plain (GCP) (1300??masl). The abrupt eastward drop in relief between these provinces gives rise to unstable conditions and consequent gravitational collapse of large volcanic edifices built at the edge of the Altiplano. Eastward sloping substrate, caused by the irregular configuration of the basement rocks, is the dominant factor that controls the direction of collapsing sectors in all major volcanoes in the region to be preferentially towards the GCP. These collapses produced voluminous debris avalanches and lahars that inundated the well-developed drainages and clastic aprons that characterize the Coastal Plain. Large catastrophic collapses from Citlalte??petl, Las Cumbres, and Cofre de Perote volcanoes are well documented in the geologic record. Some of the avalanches and transformed flows have exceptionally long runouts and reach the Gulf of Mexico traveling more than 120??km from their source. So far, no direct evidence has been found for magmatic activity associated with the initiation of these catastrophic flank-collapses. Apparently, instability of the volcanic edifices has been strongly favored by very intense hydrothermal alteration, abrupt topographic change, and intense fracturing. In addition to the eastward slope of the substrate, the reactivation of pre-volcanic basement structures during the Late Tertiary, and the E-W to ENE-SSW oriented regional stress regimes may have played an important role in the preferential movement direction of the avalanches and flows. In addition to magmatic-hydrothermal processes, high amounts of rainfall in the area is another factor that enhances alteration and eventually weakens the rocks. It is very likely that seismic activity may be the principal triggering mechanism that caused the flank collapse of large volcanic edifices in the Eastern Mexican Volcanic Belt. However, critical pore water pressure from extraordinary amounts of rainfall associated with hurricanes or other meteorological perturbation cannot be ruled out, particularly for smaller volume collapses. There are examples in the area of small seismogenic debris flows that have occurred in historical times, showing that these processes are not uncommon. Assessing the stability conditions of major volcanic edifices that have experienced catastrophic sector collapses is crucial for forecasting future events. This is particularly true for the Eastern Mexican Volcanic Belt, where in many cases no magmatic activity was associated with the collapse. Therefore, edifice failure could occur again without any precursory warning. ?? 2006 Elsevier B.V. All rights reserved.

Journal of Volcanology and Geothermal Research↗
USGS2005

Estimation of nutrient sources and transport for New Zealand using the hybrid mechanistic-statistical model SPARROW

The hybrid mechanistic-statistical catchment model SPARROW was applied to predict the mean annual load of nitrogen and phosphorus in streams throughout New Zealand (270,000 km2). The loads from land areas, point sources, and erosion are routed through the drainage network (576,300 reaches) with first-order stream decay and attenuation in lakes and reservoirs. Model parameters were determined by calibration against loads measured in the national water quality network (77 sites). For nitrogen, the model predicted the measured loads well (R2 of 0.956 and RMSE of 0.33 in natural-log space), while for phosphorus the model fit was not as good (R2 of 0.900 and RMSE of 0.58). The predictions of exported yields for streams with catchments > 20 km2 are broadly comparable with previous compilations of yields for various land-use classes for nitrogen, but are larger than the previous measurements for phosphorus. The calibrated stream attenuation and lake/reservoir rates were broadly consistent with previous measurements. The predicted load of total nitrogen (TN) delivered to the coast was 167,700 t yr-1, which is 45% of the loads entering the streams. For total phosphorus (TP) the predicted load to the coast was 63,100 t yr-1, 44% of the load entering the streams. Reservoir/lake attenuation makes a relatively small contribution to the overall attenuation compared with in-stream attenuation (3.5% for nitrogen and 8.5% for phosphorus). The largest contribution of total nitrogen is from pastoral land uses, together accounting for 70% of the total nitrogen load to the coast. Land used for dairying makes a disproportionately large contribution to the load of total nitrogen in relation to the area of land (37% of the load versus 6.8% of the land). For total phosphorus, the highest contribution of the load to the coast is from erosion (53.2%). Point sources contribute only a small proportion of the load to the coast (3.2% for nitrogen, 1.8% for total phosphorus). The monitoring network does not include streams with catchments smaller than 10 km2, so model predictions for streams smaller than 10 km2 should be used with caution. ?? New Zealand Hydrological Society (2005).

Journal of Hydrology New Zealand↗
USGS2022

Scientific results of the Hydrate-01 Stratigraphic Test Well Program, Western Prudhoe Bay Unit, Alaska North Slope

The United States Department of Energy, the MH21-S Research Consortium of Japan, and the United States Geological Survey are collaborating to enable gas hydrate scientific drilling and extended-duration reservoir response testing on the Alaska North Slope. To feasibly execute such a test, a location is required that is accessible from existing roads and gravel pads and that can be occupied without disrupting ongoing industry operations. A review of potential locations meeting these criteria determined the likely occurrence of gas hydrate in two fine-grained marginal-marine sands of Tertiary age in the vicinity of the inactive “Kuparuk State 7-11-12” exploration pad in the western Prudhoe Bay Unit (PBU). Existing well and seismic data for that site were insufficient to preclude the potential for free gas occurrence within the deeper (and most prospective) target sand. Therefore, with support from the PBU Working Interest Owners, Alaska Department of Natural Resources, and Petrotechnical Resources Alaska, the Hydrate-01 Stratigraphic Test Well (STW) was drilled in December 2018 to confirm the suitability of the site for future gas hydrate scientific testing. The Hydrate-01 well was successfully drilled to −3290 ft (1003 m) subsea vertical depth at a bottom hole location of approximately 900 ft (∼275 m) east of the surface location. The drilling program featured acquisition of a full suite of logging while drilling data, the collection of side-wall pressure cores, and the installation of distributed temperature and distributed acoustic sensor fiber-optic cables. The log data acquired confirmed the occurrence of gas hydrate at high saturation in two target sands. Integrated evaluation of log and sidewall core data provide petrophysical and geomechanical property information that allow for potential reservoir response to depressurization to be simulated. The deeper “B1 sand” is deemed to be most favorable for reservoir response testing as a result of confirmed gas hydrate occurrence in sediments of high intrinsic permeability, location within 100 ft (30 m) of the base of gas hydrate stability, and minimal risk for direct communication with permeable water-bearing (hydrate-free) zones. The shallower “D1 sand” provides a secondary target that is differentiated by colder in situ temperatures and the interpreted direct hydraulic communication to a lower section of non-hydrate-bearing, water-saturated sand. The Hydrate-01 log data also confirm the occurrence of at least one sub-seismic fault in close proximity to the B1 sand reservoir. To better image the distribution of the gas-hydrate-bearing reservoir sections and associated faults, a three-dimensional (3D) vertical seismic profile was conducted in early 2019 using the distributed acoustic sensors installed as part of the Hydrate-01 STW completion. Detailed two-dimensional (2D) and 3D geologic models have been constructed to enable numerical simulations to inform the planning for potential future scientific tests of reservoir response to depressurization at the site.

Alaska↗