Skip to main content
Advanced Search

Filters: Tags: Magnetic properties (X)

9 results (10ms)   

View Results as: JSON ATOM CSV
The recognition and characterization of aeolian dust in soil contribute to a better understanding of landscape and ecosystem dynamics of drylands. Results of this study show that recently deposited dust, sampled in isolated, mostly high-ground settings, is chemically and mineralogically similar on varied geologic substrates over a large area (15 000 km2) in the Mojave Desert. The silt-plus-clay fraction (fines) on these isolated surfaces is closely alike in magnetic-mineral composition, in contrast to greatly dissimilar magnetic compositions of rock surfaces of vastly different lithologies, on which the fines have accumulated. The fines, thus, are predominantly deposited dust. The amounts of potential nutrients...
thumbnail
The U.S. Geological Survey (USGS) collected over 1,840 physical property measurements on selected plutons in the Great Basin, primarily in California and Nevada. Data include station identifier, geographic coordinates, rock type, density, magnetic susceptibility, remanent magnetization, declination, and inclination where available. Data are presented in ASCII format and include density and magnetic property data in pluton_data.csv, a data dictionary describing the data fields in data_dictionary.csv, and a rock data dictionary listing rock types in rock_dictionary.csv. Preliminary results and interpretation were described by Ponce and others (2010) and some samples are from Sikora and others (1991). References: Ponce,...
The U.S. Geological Survey (USGS) has collected or incorporated over 20,000 physical property measurements into an ASCII database. These data are primarily from the western U.S. and Alaska and are dominated by granitic rock samples from the Sierra Nevada (compiled by Sikora and others, 1991), but also include a range of other commonly found rocks types. The data include density, magnetic susceptibility, and in some cases, remanent magnetic properties. Density data for more recently collected samples include grain, dry-bulk, and saturated-bulk density measurements. Sample locations are in the North American Datum of 1927 (NAD27) and elevations are in the National Geodetic Vertical Datum of 1929 (NGVD29). These physical...
The recognition and characterization of aeolian dust in soil contribute to a better understanding of landscape and ecosystem dynamics of drylands. Results of this study show that recently deposited dust, sampled in isolated, mostly high-ground settings, is chemically and mineralogically similar on varied geologic substrates over a large area (15 000 km2) in the Mojave Desert. The silt-plus-clay fraction (fines) on these isolated surfaces is closely alike in magnetic-mineral composition, in contrast to greatly dissimilar magnetic compositions of rock surfaces of vastly different lithologies, on which the fines have accumulated. The fines, thus, are predominantly deposited dust. The amounts of potential nutrients...
thumbnail
Aeolian dust strongly influences ecology and landscape geochemistry over large areas that span several desert ecosystems of the southwestern United States. This study evaluates spatial and temporal variations and trends of the physical and chemical properties of dust in the southwestern United States by examining dust deposited in natural depressions on high isolated surfaces along a transect from the Mojave Desert to the central Colorado Plateau. Aeolian dust is recognized in these depressions on the basis of textural, chemical, isotopic, and mineralogical characteristics and comparisons of those characteristics to the underlying bedrock units. Spatial and temporal trends suggest that although local dust sources...
thumbnail
Efforts by the USGS to characterize regional geology of the southeastern Mojave Desert near Mountain Pass, California, include 1,061 rock samples collected along the southern California/Nevada border. Rock property measurements include density, magnetic susceptibility, and radiometric concentrations to understand structural and geophysical relationships associated with rare earth element mineral deposits. Notable rock types sampled include, but are not limited to, carbonatite, dolomite, gneiss, granite, granodiorite, limestone, quartzite, sandstone, shonkinite, syenite, and volcanic rocks spanning the study area.
thumbnail
Rock-derived nutrients in soils originate from both local bedrock and atmospheric dust, including dust from far-distant sources. Distinction between fine particles derived from local bedrock and from dust provides better understanding of the landscape-scale distribution and abundance of soil nutrients. Sandy surficial deposits over dominantly sandstone substrates, covering vast upland areas of the central Colorado Plateau, typically contain 5–40% silt plus clay, depending on geomorphic setting and slope (excluding drainages and depressions). Aeolian dust in these deposits is indicated by the presence of titanium-bearing magnetite grains that are absent in the sedimentary rocks of the region. Thus, contents of...
Sediments in Marshall and Hidden Lakes in the Uinta Mountains of northeastern Utah contain records of atmospheric mineral-dust deposition as revealed by differences in mineralogy and geochemistry of lake sediments relative to Precambrian clastic rocks in the watersheds. In cores spanning more than a thousand years, the largest changes in composition occurred within the past approximately 140 years. Many elements associated with ore deposits (Ag, As, Bi, Cd, Cu, In, Mo, Pb, S, Sb, Sn, and Te) increase in the lake sediments above depths that correspond to about AD 1870. Sources of these metals from mining districts to the west of the Uinta Mountains are suggested by (1) the absence of mining and smelting of these...
The recognition and characterization of aeolian dust in soil contribute to a better understanding of landscape and ecosystem dynamics of drylands. Results of this study show that recently deposited dust, sampled in isolated, mostly high-ground settings, is chemically and mineralogically similar on varied geologic substrates over a large area (15 000 km2) in the Mojave Desert. The silt-plus-clay fraction (fines) on these isolated surfaces is closely alike in magnetic-mineral composition, in contrast to greatly dissimilar magnetic compositions of rock surfaces of vastly different lithologies, on which the fines have accumulated. The fines, thus, are predominantly deposited dust. The amounts of potential nutrients...
    map background search result map search result map Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients Compositional trends in aeolian dust along a transect across the southwestern United States Density and magnetic properties of selected plutons (granitoids) in the Great Basin, parts of Arizona, California, Idaho, Nevada, Oregon, and Utah Whole Rock Density, Magnetic Susceptibility, and Radiometric Measurements of a Rare Earth Element Terrane, Southeastern Mojave Desert, California and Nevada Density and Magnetic Properties of Selected Rock Samples from the Western U.S. and Alaska Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients Whole Rock Density, Magnetic Susceptibility, and Radiometric Measurements of a Rare Earth Element Terrane, Southeastern Mojave Desert, California and Nevada Compositional trends in aeolian dust along a transect across the southwestern United States Density and magnetic properties of selected plutons (granitoids) in the Great Basin, parts of Arizona, California, Idaho, Nevada, Oregon, and Utah Density and Magnetic Properties of Selected Rock Samples from the Western U.S. and Alaska