SEARCH · Search USGS

Results for “Scanning”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

USGS1989

Side-scan sonar mapping of lake trout spawning habitat in northern Lake Michigan

Native stocks of lake trout Salvelinus namaycush were virtually or completely extirpated from the lower four Great Lakes by the early 1960s. The failure of early attempts to reestablish self-sustaining populations of lake trout was attributed partly to the practice of stocking hatcheryreared juveniles at locations and over substrates that had not been used in the past for spawning by native fish. Subsequent attempts to improve the selection of stocking locations were impeded by the lack of reliable information on the distribution of substrates on historical spawning grounds. Here we demonstrate the potential of side-scan sonar to substantially expand the data base needed to pinpoint the location of substrates where lake trout eggs, fry, or juveniles could be stocked to maximize survival and help ensure that survivors returning to spawn would encounter suitable substrates. We also describe the substrates and bathymetry of large areas on historical lake trout spawning grounds in the Fox Island Lake Trout Sanctuary in northern Lake Michigan. These areas could be used to support a contemporary self-sustaining lake trout population in the sanctuary and perhaps also in adjacent waters.

Great Lakes↗

USGS2026

An assessment of the quality of microanalysis of natural silicate glass using scanning electron microscope-based energy dispersive spectrometry (SEM-EDS)

The composition of volcanic glass records important clues into the origin and evolution of magmatic systems. However, the analysis of volcanic glass presents challenges when performed using electron-beam techniques, particularly due to Na mobility. While microanalysis of geological materials is usually performed using electron probe microanalyzer-based wavelength-dispersive spectrometry (EPMA-WDS), we present here results of glass analysis using energy-dispersive spectrometry with a scanning electron microscope (SEM-EDS). We use three U.S. Geological Survey (USGS) whole-rock reference materials (i.e., RGM-1, STM-1, QLO-1) that were fused into glass using a double-fusion technique. Results for 12 sessions over two months using the SEM-EDS reveal excellent reproducibility, agreement with the expected values for RGM-1 and STM-1, and excellent counting statistics when using live acquisition times of 15 s; results for QLO-1 suggest that the fused material is somewhat inhomogeneous. For longer acquisition times (30, 60, 90 s), significant Na migration is observed; we conclude that minimal Na migration takes place with acquisition times of 15 s using our analytical instrumentation. We also compile data for RGM-1 obtained using the same instrument over the last decade, and we further demonstrate the reliability of SEM-EDS for microanalysis of silicate glasses. Comparison of our results with EPMA-WDS results for a range of reference materials published by researchers at the USGS Alaska Volcano Observatory suggest that both EPMA-WDS and SEM-EDS can yield adequate analysis of volcanic glass, but SEM-EDS can potentially lead to higher precision for major elements (>1 wt.% concentration), while EPMA-WDS typically leads to higher precision for minor elements. The higher precision of SEM-EDS results for major elements, combined with the more widespread distribution, lower usage cost, and higher ease of use of such systems, makes analysis via SEM-EDS an attractive option for measuring major-element compositions of volcanic glass. However, it is critical to test the quality of each instrument given differences in hardware and software between SEM and EDS systems.

American Mineralogist↗

USGS2016

Modeling streamflow from coupled airborne laser scanning and acoustic Doppler current profiler data

The rating curve enables the translation of water depth into stream discharge through a reference cross-section. This study investigates coupling national scale airborne laser scanning (ALS) and acoustic Doppler current profiler (ADCP) bathymetric survey data for generating stream rating curves. A digital terrain model was defined from these data and applied in a physically based 1-D hydraulic model to generate rating curves for a regularly monitored location in northern Sweden. Analysis of the ALS data showed that overestimation of the streambank elevation could be adjusted with a root mean square error (RMSE) block adjustment using a higher accuracy manual topographic survey. The results of our study demonstrate that the rating curve generated from the vertically corrected ALS data combined with ADCP data had lower errors (RMSE = 0.79 m 3 /s) than the empirical rating curve (RMSE = 1.13 m 3 /s) when compared to streamflow measurements. We consider these findings encouraging as hydrometric agencies can potentially leverage national-scale ALS and ADCP instrumentation to reduce the cost and effort required for maintaining and establishing rating curves at gauging station sites similar to the Röån River.

Hydrology Research↗

USGS2026

A scanning electron microscope-energy dispersive spectrometry (SEM-EDS) method for the quantitative analysis of common volcanic phases

In situ microanalysis by X-ray spectrometry is a fundamental geochemical technique for volcanology and the geosciences generally and typically performed using an electron microprobe (EPMA) equipped with wavelength dispersive spectrometers (WDS). The related technique of energy dispersive spectrometry (EDS), implemented using either EPMA or a scanning electron microscope (SEM), offers advantages in throughput, simplicity, and cost, yet has historically been relegated to qualitative tasks. We present a quantitative EDS procedure implemented using a W-source SEM and a moderate size silicon drift EDS detector applied to common volcanic materials. Glass and mineral standard data demonstrate that the accuracy and precision of this method is comparable to EPMA–WDS. We show that electron beam damage can be mitigated in volcanic glass through sample-specific optimizations without the need for a time-dependent intensity correction. Our implementation using a relatively inexpensive instrument can potentially increase the accessibility of high-quality, quantitative X-ray microanalysis of major and minor elements.

Volcanica↗

USGS2017

Scanning and georeferencing historical USGS quadrangles

The U.S. Geological Survey (USGS) National Geospatial Program is scanning published USGS 1:250,000-scale and larger topographic maps printed between 1884, the inception of the topographic mapping program, and 2006. The goal of this project, which began publishing the Historical Topographic Map Collection in 2011, is to provide access to a digital repository of USGS topographic maps that is available to the public at no cost. For more than 125 years, USGS topographic maps have accurately portrayed the complex geography of the Nation. The USGS is the Nation’s largest producer of traditional topographic maps, and, prior to 2006, USGS topographic maps were created using traditional cartographic methods and printed using a lithographic process. The next generation of topographic maps, US Topo, is being released by the USGS in digital form, and newer technologies make it possible to also deliver historical maps in the same electronic format that is more publicly accessible.

Fact Sheet↗

USGS2010

Examination of Libby, Montana, Fill Material for Background Levels of Amphibole from the Rainy Creek Complex Using Scanning Electron Microscopy and X-Ray Microanalysis

Natural background levels of Libby-type amphibole in the sediment of the Libby valley in Montana have not, up to this point, been determined. The purpose of this report is to provide the preliminary findings of a study designed by both the U.S. Geological Survey and the U.S. Environmental Protection Agency and performed by the U.S. Geological Survey. The study worked to constrain the natural background levels of fibrous amphiboles potentially derived from the nearby Rainy Creek Complex. The material selected for this study was sampled from three localities, two of which are active open-pit sand and gravel mines. Seventy samples were collected in total and examined using a scanning electron microscope equipped with an energy dispersive x-ray spectrometer. All samples contained varying amounts of feldspars, ilmenite, magnetite, quartz, clay minerals, pyroxene minerals, and non-fibrous amphiboles such as tremolite, actinolite, and magnesiohornblende. Of the 70 samples collected, only three had detectable levels of fibrous amphiboles compatible with those found in the rainy creek complex. The maximum concentration, identified here, of the amphiboles potentially from the Rainy Creek Complex is 0.083 percent by weight.

Open-File Report↗

USGS2022

Results of automated scanning electron microscope (SEM) analyses of rock and stream sediment samples from the Taurus porphyry copper deposit area, Tanacross quadrangle, eastern Alaska

Numerous porphyry copper-molybdenum-gold and epithermal deposits define a belt that extends from Eastern Alaska to western Yukon, Canada. An orientation study conducted near the Taurus porphyry deposit was designed to test methods that require minimal sample collection, preparation, and analytical time to determine the viability of indicator mineral studies as a reconnaissance exploration method. Bulk stream sediments and altered and mineralized rocks were sieved to the 0.105−0.25 millimeter fraction (+140, −60 mesh) and passed over a shaking table to create a moderate to heavy mineral separate that was mounted in epoxy and subsequently analyzed using automated scanning electron microscope (SEM) techniques. Seven polished thin sections of core were also analyzed. Among the advantages of automated SEM techniques compared to visual mineral identification are that thousands of grains can be rapidly identified in each sample (about 1 hour per sample) and small quantities of indicator minerals that may be missed during traditional visual analyses can be detected. Automated SEM analyses of stream sediment and rock samples show that specific minerals (chalcopyrite, bornite, and jarosite) are indicators of potential mineralized areas. Svanbergite, an aluminum sulfate phosphate mineral, was identified in mineralized rocks and in nearly all stream sediment samples (up to 9 kilometers) downstream from the Taurus and other porphyry occurrences but not epithermal occurrences. It was not identified in areas with no known mineralization and thus it is possibly one of the best indicator minerals for porphyry copper (+/- molybdenum, gold) occurrences.

Alaska↗

USGS1968

Dispersive multispectral scanning; a feasibility study

Optical-mechanical line scanners can be used from aircraft and satellites to obtain strip maps of the surface over which the vehicle passes. The feasibility of combining wavelength dispersing techniques with such scanning techniques has been studied. This combination makes it possible to obtain spectral and spatial information simultaneously. Appropriate data processing techniques will then permit us to interpret the spectral data to produce surface maps of various kinds, such as maps of crop type or of surface geology. Parametric equations representing a generalized dispersive multispectral scanner are developed and discussed in the light of subsystem and component state of the art and from the point of view of prospective users such as geologists and agriculturalists.

Open-File Report↗

USGS1978

High resolution seismic profiles, side scan sonar records, and sampling locations from lower Cook Inlet and Kodiak Shelf, R/V SEA SOUNDER cruise S7-77-WG, September - October, 1977

During the period from September 14 through October 10, 1977 the second U.S. Geological Survey geo-environmental cruise was conducted in lower Cook Inlet and on the Kodiak shelf and adjacent upper continental slope, Gulf of Alaska, aboard the R/V SEA SOUNDER (Figure 1, Tables 1, 2 and 3). The objective of this cruise was to study in detail specific potentially hazardous environmental conditions identified as a result of the first reconnaissance geo-environmental cruise conducted from June 18 through July 30, 1976 (Bouma and Hampton, 1976; Hampton and Bouma, 1976). In particular, the distribution and movement of seafloor bedforms were studied in lower Cook Inlet, and sediment dispersal patterns and submarine sediment slides were investigated on the Kodiak shelf and slope. High resolution seismic profiling (sparker, uniboom, minisparker, 3.5 khz, 12 khz) and side-scanning sonar surveys formed the basis for selecting stations for observations with bottom television and 70 mm bottom camera as well as for different types of sampling of surficial sediments (piston corer, gravity corer, hydroplastic corer, Soutar grab sampler). The success of the 1977 cruise was limited by adverse weather conditions.

Alaska↗

USGS1979

Single-Channel Seismic-Reflection Profiles and Side-Scan Sonar Records Collected During June 8-14, 1977, in the Middle Atlantic Shelf Area

A cruise aboard the R/V OCEANUS (Cruise 027) was completed by the U.S. Geological Survey during June 8-14, 1977evaluate the presence, extent, and activity of potentially mobile bedforms on the Middle Atlantic Continental Shelf, eastern United States. Based on information collected by the U.S. Geological Survey during·a geophysical survey in 1975, seven sites showing possible bedforms were selected for detailed study. At each of the seven study areas, single-channel high-resolution seismic profiling and side-scan sonar techniques were used to identify and map the size, distribution, and orientation of the different types of bedforms that were present.

Open-File Report↗

USGS1993

Oxygen-isotope, X-ray-diffraction and scanning-electron-microscope examinations of authigenic-layer-silicate minerals from Mississippian and Pennsylvanian sandstones in the Michigan Basin

Oxygen-isotope compositions of authigenic-layer silicates (<2-micrometer fraction) extracted from Mississippian and Pennsylvanian sandstones in the Lower Peninsula of Michigan were determined. Petrographic and scanning-electron-microscope examinations, and X-ray diffractograms show that chlorite and kaolinite are the most common authigenic-layer silicates in Mississippian sandstones. The range of oxygen-isotope compositions of chlorite and kaolinite are +10.3 to +11.9 and +12.9 to +19.3 pars per thousand (per mil) (relative to Standard Mean Ocean Water), respectively. Kaolinite is the only authigenic-isotopic compositions of kaolinite range from +16.8 to +19.0 per mil.

Michigan↗

USGS1998

MORPH-I (Ver 1.0) a software package for the analysis of scanning electron micrograph (binary formatted) images for the assessment of the fractal dimension of enclosed pore surfaces

MORPH-I is a set of C-language computer programs for the IBM PC and compatible minicomputers. The programs in MORPH-I are used for the fractal analysis of scanning electron microscope and electron microprobe images of pore profiles exposed in cross-section. The program isolates and traces the cross-sectional profiles of exposed pores and computes the Richardson fractal dimension for each pore. Other programs in the set provide for image calibration, display, and statistical analysis of the computed dimensions for highly complex porous materials. Requirements: IBM PC or compatible; minimum 640 K RAM; mathcoprocessor; SVGA graphics board providing mode 103 display.

Open-File Report↗

USGS2023

Scanning electron microscope images of sand and silt from the early MIS4–MIS3 Roxana Silt, Phillips Bayou, Arkansas

The age and source of the late Pleistocene Roxana Silt in the Mississippi Valley have been studied since the middle 1800s. Published age and paleoenvironmental data for the Roxana Silt in the Mississippi Valley show that deposition occurred from late marine isotope stage 5 (MIS5) through late marine isotope stage 3 (MIS3) (80–30 kilo-annum [ka]), when the warm to hot interglacial climate of early to middle MIS5 (about 130 to about 80 ka) was transitioning to a considerably cooler and wetter climate. Scanning electron microscopy/energy dispersive X-ray (SEM/EDS) analysis of silt and sand grains from the Roxana Silt exposed in an abandoned borrow pit near Phillips Bayou, Arkansas, was performed as part of a 1990s study of late middle and late Pleistocene loess in the unglaciated lower Mississippi Valley. Results from that study were summarized in 1990s publications, but the data for sand and silt grain morphology and mineralogy were not published. Some of the SEM/EDS analyses of the Roxana Silt from that late 1990s study are presented in this report. Combined with previously published chronostratigraphic and pedostratigraphic data for the Roxana Silt at Phillips Bayou, the SEM/EDS data indicate some degree of syndepositional weathering and pedogenic alteration during and after gradual eolian deposition in late marine isotope stage 4 (MIS4) and MIS3 (about 60 to about 30 ka). Results from the SEM/EDS analyses support previously published paleoclimate interpretations indicating that at least as far south as northern Mississippi, the climate of the Mississippi Valley in MIS4 and MIS3 (about 70 to about 30 ka) was cool to cold and humid to wet.

Arkansas↗

USGS1996

Using a geographic information system and scanning technology to create high-resolution land-use data sets

A geographic information system (GIS) procedure was developed to compile low-altitude aerial photography, digitized data, and land-use data from U.S. Department of Agriculture Consolidated Farm Service Agency (CFSA) offices into a high-resolution (approximately 5 meters) land-use GIS data set. The aerial photography consisted of 35-mm slides which were scanned into tagged information file format (TIFF) images. These TIFF images were then imported into the GIS where they were registered into a geographically referenced coordinate system. Boundaries between land use were delineated from these GIS data sets using on-screen digitizing techniques. Crop types were determined using information obtained from the U.S. Department of Agriculture CFSA offices. Crop information not supplied by the CFSA was attributed by manual classification procedures. Automated methods to provide delineation of the field boundaries and land-use classification were investigated. It was determined that using these data sources, automated methods were less efficient and accurate than manual methods of delineating field boundaries and classifying land use.

Water-Resources Investigations Report↗

USGS2021

Using fission-track radiography coupled with scanning electron microscopy for efficient identification of solid-phase uranium mineralogy at a former uranium pilot mill (Grand Junction, Colorado)

At a former uranium pilot mill in Grand Junction, Colorado, mine tailings and some subpile sediments were excavated to various depths to meet surface radiological standards, but residual solid-phase uranium below these excavation depths still occurs at concentrations above background. The combination of fission-track radiography and scanning electron microscope energy-dispersive X-ray spectroscopy (SEM-EDS) provides a uniquely efficient and quantitative way of determining mineralogic associations of uranium that can influence uranium mobility. After the creation of sample thin sections, a mica sheet is placed on those thin sections and irradiated in a nuclear research reactor. Decay of the irradiated uranium creates fission tracks that can be viewed with a microscope. The fission-track radiography images indicate thin section sample areas with elevated uranium that are focus areas for SEM-EDS work. EDS spectra provide quantitative elemental data that indicate the mineralogy of individual grains or grain coatings associated with the fission-track identification of elevated uranium. For the site in this study, the results indicated that uranium occurred (1) with coatings of aluminum–silicon (Al/Si) gel and gypsum, (2) dispersed in the unsaturated zone associated with evaporite-type salts, and (3) sorbed onto organic carbon. The Al/Si gel likely formed when low-pH waters were precipitated during calcite buffering, which in turn retained or precipitated trace amounts of Fe, As, U, V, Ca, and S. Understanding these mechanisms can help guide future laboratory and field-scale efforts in determining long-term uranium release rates to groundwater.

Colorado↗

USGS2011

Hydrologic conditions and terrestrial laser scanning of post-firedebris flows in the San Gabriel Mountains, CA, U.S.A

To investigate rainfall-runoff conditions that generate post-wildfire debris flows, we instrumented and surveyed steep, small watersheds along the tectonically active front of the San Gabriel Mountains, California. Fortuitously, we recorded runoff-generated debris-flows triggered by one spatially restricted convective event with 28 mm of rainfall falling over 62 minutes. Our rain gages, nested hillslope overland-flow sensors and soil-moisture probes, as well as a time series of terrestrial laser scanning (TLS) revealed the effects of the storm. Hillslope overland-flow response, along two ~10-m long flow lines perpendicular to and originating from a drainage divide, displayed only a 10 to 20 minute delay from the onset of rainfall with accumulated totals of merely 5-10 mm. Depth-stratified soil-moisture probes displayed a greater time delay, roughly 20- 30 minutes, indicating that initial overland flow was Hortonian. Furthermore, a downstream channel-monitoring array recorded a pronounced discharge peak generated by the passage of a debris flow after 18 minutes of rainfall. At this time, only four of the eleven hillslope overland flow sensors confirmed the presence of surface-water flow. Repeat TLS and detailed field mapping using GPS document how patterns of rainsplash, overland-flow scour, and rilling contributed to the generation of metter-scale debris flows. In response to a single small storm, the debris flows deposited irregular levees and lobate terminal snouts on hillslopes and caused wide- spread erosion of the valley axis with ground surface lowering exceeding 1.5 m.

California↗

USGS2024

In situ lung dust analysis by automated Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy: A method for assessing inorganic particles in tissue from coal miners

Context.— Overexposure to respirable coal mine dust can cause severe lung disease including progressive massive fibrosis (PMF). Field emission scanning electron microscopy with energy dispersive x-ray spectroscopy (FESEM-EDS) has been used for in situ lung dust particle analysis for evaluation of disease etiology. Automating such work can reduce time, costs, and user bias. Objective.— To develop and test an automated FESEM-EDS method for in situ analysis of inorganic particles in coal miner lung tissue. Design.— We programmed an automated FESEM-EDS procedure to collect particle size and elemental data, using lung tissue from 10 underground coal miners with PMF and 4 control cases. A statistical clustering approach was used to establish classification criteria based on particle chemistry. Data were correlated to PMF/non-PMF areas of the tissue, using corresponding brightfield microscopy images. Results for each miner case were compared with a separate corresponding analysis of particles recovered following tissue digestion. Results.— In situ analysis of miner tissues showed higher particle number densities than controls and densities were generally higher in PMF than non-PMF areas. Particle counts were typically dominated by aluminum silicates with varying percentages of silica. Compared to digestion results for the miner tissues, in situ results indicated lower density of particles (number per tissue volume), larger size, and a lower ratio of silica to total silicates—probably due to frequent particle clustering in situ. Conclusions.— Automated FESEM-EDS analysis of lung dust is feasible in situ and could be applied to a larger set of mineral dust–exposed lung tissues to investigate specific histologic features of PMF and other dust-related occupational diseases.

Archives of Pathology↗

USGS2010

Observations of drainage network change in a recently burned watershed using terrestrial laser scanning

Wildfire enhances the geomorphic response of a watershed to precipitation events, effectively altering the form of the hillslope and channel drainage network. Typically, drainage networks expand following rainfall on a recently burned watershed. Expansion of drainage networks following wildfire increases in erosion and sediment transport rates, and the probability of flash-flooding and debris-flows at downstream locations. Observations of the response of hillslope and channel drainage to individual precipitation events are vital to unraveling the dynamics of erosion processes in recently burned watersheds. Here, we apply terrestrial laser scanning (TLS) methods to produce digital terrain models (DTMs) of a recently burned watershed at an unprecedented spatial resolution. The DTM data aid the quantification of changes in the hillslope and channel drainage networks at several spatial scales. Two TLS surveys were conducted, one survey between 28-30 September 2008 to document pre-rainfall conditions, and one between 18-21 December 2008, three days after 52 mm of rainfall over a period of 22 hours. A Leica Geosystems ScanStation 2 TLS was used to generate 1 cm resolution DTMs, from which the hillslope and channel drainage networks were derived. The location and magnitude of erosion and deposition for each pixel within the basin was determined by calculating the topographic differences between DTMs. Changes in the drainage network morphology were identified through the analysis of bifurcation ratio, drainage density (including rills), rill length, horizontal migration of rills, width-depth ratios and upstream migration of knickpoints. Comparisons of these measures were made between morphologically distinct sub-basins within the study area, and between surveys. Analyses of bifurcation ratios, and measures of rill position and gullyhead migration indicate an expansion of the rill network and upstream migration of knickpoints. These results suggest that expansion of the drainage network is a function of boundary conditions that exist at multiple spatial scales, including depth to bedrock, surface roughness, and contributing area. Additional predictive capability at this spatial and temporal resolution is going to require a physically-based model capable of combining high-resolution topographic changes and process information from in-situ measurements of flow dynamics.

Conference Paper↗