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At least 307 records · Page 17Linked to original sources
USGS2020

Pyrrhotite distribution in the conterminous United States, 2020

In parts of Connecticut and Massachusetts, foundations of some homes are cracking and crumbling. Failing foundations can reduce the market value of a home and lifting a house to replace and repour a foundation is an expensive undertaking. In response, some homeowners are defaulting on their mortgages and abandoning their homes. The culprit is pyrrhotite, which occurs in construction aggregate (crushed stone) that was used as a filler in concrete. When pyrrhotite is naturally exposed to water and oxygen, it breaks down to produce sulfuric acid and secondary minerals, including gypsum, which have larger volumes than the pyrrhotite they replace. The expanded volume of the secondary minerals cracks and degrades concrete. Pyrrhotite occurs in rocks in many areas of the United States. To help assess the national risk of pyrrhotite in aggregate, the fiscal year 2019 appropriations bill for the U.S. Geological Survey’s (USGS) Mineral Resources Program allocated funds to develop a map showing the distribution of pyrrhotite across the United States. The purpose of this fact sheet is to (1) present a nationwide map that shows where pyrrhotite may occur in rocks in the United States, (2) describe and discuss the factors that control the presence and abundance of pyrrhotite in rocks, (3) provide information on geographic information system datasets that deliver more detailed information on these distributions, and (4) describe U.S. and international standards on aggregate that are designed to prevent failing concrete. While this map and fact sheet provide general information about the possible distribution of pyrrhotite in the United States, they are no substitute for site-specific characterization and quality control programs designed to ensure that aggregate used in concrete is of appropriate quality for its intended purpose.

Conterminous United States↗
USGS2011

Bedrock geologic map of the Seward Peninsula, Alaska, and accompanying conodont data

This 1:500,000-scale geologic map depicts the bedrock geology of Seward Peninsula, western Alaska, on the North American side of the Bering Strait. The map encompasses all of the Teller, Nome, Solomon, and Bendeleben 1:250,000-scale quadrangles, and parts of the Shishmaref, Kotzebue, Candle, and Norton Bay 1:250,000-scale quadrangles (sh. 1; sh. 2). The geologic map is presented on Sheet 1. The pamphlet includes an introductory text, detailed unit descriptions, tables of geochronologic data, and an appendix containing conodont (microfossil) data and a text explaining those data. Sheet 2 shows metamorphic and tectonic units, conodont color alteration indices, key metamorphic minerals, and locations of geochronology samples listed in the pamphlet. The map area covers 74,000 km 2 , an area slightly larger than West Virginia or Ireland.

Alaska↗
USGS2015

Offshore geology and geomorphology from Point Piedras Blancas to Pismo Beach, San Luis Obispo County, California

Marine geology and geomorphology were mapped along the continental shelf and upper slope between Point Piedras Blancas and Pismo Beach, California. The map area is divided into the following three (smaller) map areas, listed from north to south: San Simeon, Morro Bay, and Point San Luis. Each smaller map area consists of a geologic map and the corresponding geophysical data that support the geologic mapping. Each geophysical data sheet includes shaded-relief multibeam bathymetry, seismic-reflection-survey tracklines, and residual magnetic anomalies, as well as a smaller version of the geologic map for reference. Offshore geologic units were delineated on the basis of integrated analysis of adjacent onshore geology, seafloor-sediment and rock samples, multibeam bathymetry and backscatter imagery, magnetic data, and high-resolution seismic-reflection profiles. Although the geologic maps are presented here at 1:35,000 scale, map interpretation was conducted at scales of between 1:6,000 and 1:12,000. Sea level was approximately 120 to 130 m lower during the Last Glacial Maximum (about 21 ka). This approximate depth corresponds to the modern shelf break, a lateral change from the gently dipping (0.8° to 1.0°) outer shelf to the slightly more steeply dipping (about 1.5° to 2.5°) upper slope in the central and northern parts of the map area. South of Point San Luis in San Luis Bay, deltaic deposits offshore of the mouth of the Santa Maria River (11 km south of the map area) have prograded across the shelf break and now form a continuous low-angle (about 0.8°) ramp that extends to water depths of more than 160 m. The shelf break defines the landward boundary of slope deposits. North of Estero Bay, the shelf break is characterized by a distinctly sharp slope break that is mapped as a landslide headscarp above landslide deposits. Multibeam imagery and seismic-reflection profiles across this part of the shelf break show evidence of slope failure, such as slumping, sliding, and soft-sediment deformation, along the entire length of the scarp. Notably, this shelf-break scarp corresponds to a west splay of the Hosgri Fault that dies out just north of the scarp, suggesting that faulting is controlling the location (and instability) of the shelf break in this area.

California↗
USGS1877

Topographical atlas sheets

The following topographical atlas maps, published during the year, accompany the copies of Appendix N.N. of the Annual Report of the Chief of Engineers for 1877, beinig Annual Report of Lieut. Geo. M. Wheeler, Corps of Engineers, in charge of U. S. Geographical Surveys, are in continuation of the series ninety-five in number, on a scale of 1 inch to 8 miles, embracing the territory of the United States lying west of the 100th meridian.

California;Colorado;New Mexico↗
USGS1981

New maps of Federal coal

Compilation and analysis of publicly available data on Federal coal are resulting in voluminous map sets showing coal isopachs, structure contours, and overburden isopachs on each known minable coal bed. As of the spring of 1981, there are available from the U.S. Geological Survey Open-File Services Section in Denver map sets at 1:24,000 scale or microfiche sets covering approximately 470 of the ultimately 1,400 quadrangles in the program. Because Congress in 1976 mandated the prompt “inventorying” of all unleased Federal coal for Government land-use planning, and because dollars but not employee positions were provided for the work, the U.S. Geological Survey was obliged to contract for the compilations. A typical map set has a short text and about 20 plates, including a data sheet; a Federal mineral ownership map; and correlation charts. For each coal bed, there are isopachs, structure contours, stripping limits, and mining ratios extending as far as the data will permit, regardless of coal ownership. Reserve base tonnages and relative development potentials are calculated, but only for unleased Federal coal areas. Termed “minable” are coal beds at least 1.524 m (5 ft) thick and less than 914.4 m (3,000 ft) deep. For conventional underground mining methods, beds dipping more than 15° are excluded; also excluded are all but 3.66 m (12 ft) of thick beds. For in situ conversion methods, the minimum dip is 15° except for the deep thick beds in the Powder River Basin. Arbitrary parameters classify the development potential of each unleased 16.19-hectare (40-acre) tract as high, moderate, low, unknown, or negative. The former Secretary of the Interior announced his intention to restrict leasing in general to tracts classified as having high to moderate potential for development. Many geologists will find these systematic map compilations to be useful bases for adding new data points and making their own interpretations, correlations, extrapolations, and reserve estimates.

Geological Society of America Bulletin↗
USGS2008

Surficial Geologic Map of the Worcester North-Oxford- Wrentham-Attleboro Nine-Quadrangle Area in South- Central Massachusetts

The surficial geologic map layer shows the distribution of nonlithified earth materials at land surface in an area of nine 7.5-minute quadrangles (417 mi2 total) in south-central Massachusetts (fig. 1). Across Massachusetts, these materials range from a few feet to more than 500 ft in thickness. They overlie bedrock, which crops out in upland hills and in resistant ledges in valley areas. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (such as grain size and sedimentary structures), constructional geomorphic features, stratigraphic relationships, and age. Surficial materials also are known in engineering classifications as unconsolidated soils, which include coarse-grained soils, fine-grained soils, or organic fine-grained soils. Surficial materials underlie and are the parent materials of modern pedogenic soils, which have developed in them at the land surface. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for water resources, construction aggregate resources, earth-surface hazards assessments, and land-use decisions. The mapped distribution of surficial materials that lie between the land surface and the bedrock surface is based on detailed geologic mapping of 7.5-minute topographic quadrangles, produced as part of an earlier (1938-1982) cooperative statewide mapping program between the U.S. Geological Survey and the Massachusetts Department of Public Works (now Massachusetts Highway Department) (Page, 1967; Stone, 1982). Each published geologic map presents a detailed description of local geologic map units, the genesis of the deposits, and age correlations among units. Previously unpublished field compilation maps exist on paper or mylar sheets and these have been digitally rendered for the present map compilation. Regional summaries based on the Massachusetts surficial geologic mapping studies discuss the ages of multiple glaciations, the nature of glaciofluvial, glaciolacustrine, and glaciomarine deposits, and the processes of ice advance and retreat across Massachusetts (Koteff and Pessl, 1981; papers in Larson and Stone, 1982; Oldale and Barlow, 1986; Stone and Borns, 1986; Warren and Stone, 1986). This compilation of surficial geologic materials is an interim product that defines the areas of exposed bedrock and the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This surficial geologic map layer covering nine quadrangles revises previous digital surficial geologic maps (Stone and others, 1993; MassGIS, 1999) that were compiled on base maps at regional scales of 1:125,000 and 1:250,000. The purpose of this study is to provide fundamental geologic data for the evaluation of natural resources, hazards, and land information within the Commonwealth of Massachusetts.

Open-File Report↗
USGS1999

Digital Map of Surficial Geology, Wetlands, and Deepwater Habitats, Coeur d'Alene River Valley, Idaho

The Coeur d'Alene (CdA) River channel and its floodplain in north Idaho are mostly covered by metal-enriched sediments, partially derived from upstream mining, milling and smelting wastes. Relative to uncontaminated sediments of the region, metal-enriched sediments are highly enriched in silver, lead, zinc, arsenic, antimony and mercury, copper, cadmium, manganese, and iron. Widespread distribution of metal-enriched sediments has resulted from over a century of mining in the CdA mining district (upstream), poor mine-waste containment practices during the first 80 years of mining, and an ongoing series of over-bank floods. Previously deposited metal-enriched sediments continue to be eroded and transported down-valley and onto the floodplain during floods. The centerpiece of this report is a Digital Map Surficial Geology, Wetlands and Deepwater Habitats of the Coeur d'Alene (CdA) River valley (sheets 1 and 2). The map covers the river, its floodplain, and adjacent hills, from the confluence of the North and South Forks of the CdA River to its mouth and delta front on CdA Lake, 43 linear km (26 mi) to the southwest (river distance 58 km or 36 mi). Also included are the following derivative theme maps: 1. Wetland System Map; 2. Wetland Class Map; 3. Wetland Subclass Map; 4. Floodplain Map; 5. Water Regime Map; 6. Sediment-Type Map; 7. Redox Map; 8. pH Map; and 9. Agricultural Land Map. The CdA River is braided and has a cobble-gravel bottom from the confluence to Cataldo Flats, 8 linear km (5 mi) down-valley. Erosional remnants of up to four alluvial terraces are present locally, and all are within the floodplain, as defined by the area flooded in February of 1996. High-water (overflow) channels and partly filled channel scars braid across some alluvial terraces, toward down-valley marshes and (or) oxbow ponds, which drain back to the river. Near Cataldo Flats, the river gradient flattens, and the river coalesces into a single channel with a large friction-dominated central sand bar at Cataldo Landing. Metal-enriched sediments that were dredged from the central sand bar were deposited on Cataldo Flats, to form extensive dredge-spoil deposits. From the central sand bar to CdA Lake, thick deposits of metal-enriched sand partially fill the middle of the pre-mining-era channel along straight reaches, and form point-bars along the inside margins of meander bends. Metal-enriched sand and silt form oxidized bank-wedge deposits along riverside margins of pre-mining-era levees of gray silty mud. Metal-enriched levee sand deposits extend across bank wedges and natural levees, generally thinning and fining away from the river, toward lateral marshes and lakes, where dark gray metal-enriched silt and mud overlie silty peat, deposited before the mining era. Distributary streams and man-made canals locally diverge from the river, connecting it to lateral marshes and lakes, and metal-enriched sand splays locally fan out across the floodplain. At the mouth of the river, a bouyancy-dominated river-mouth bar crests beyond the ends of the emergent levees. Thick delta-front deposits of metal-enriched sand slope from the river-mouth bar to the bottom of CdA Lake.

Open-File Report↗
USGS2024

Mapping the resistivity structure of Walker Ridge 313 in the Gulf of Mexico using the marine CSEM method

A marine controlled source electromagnetic (CSEM) campaign was carried out in the Gulf of Mexico to further develop marine electromagnetic techniques in order to aid the detection and mapping of gas hydrate deposits. Marine CSEM methods are used to obtain an electrical resistivity structure of the subsurface which can indicate the type of substance filling the pore space, such as gas hydrates which are more resistive. Results from the Walker Ridge 313 study (WR 313) are presented in this paper and compared with the Gulf of Mexico Gas Hydrate Joint Industry Project II (JIP2) logging while drilling (LWD) results and available seismic data. The hydrate, known to exist within sheeted sand deposits, is mapped as a resistive region in the two dimensional (2D) CSEM inversion models. This is consistent with the JIP2 LWD resistivity results. CSEM inversions that use seismic horizons provide more realistic results compared to the unconstrained inversions by providing sharp boundaries and architectural control on the location of the resistive and conductive regions in the CSEM model. The seismic horizons include: 1) the base of the gas hydrate stability zone (BGHSZ), 2) the top of salt, and 3) the top and bottom of a fine grained marine mud interval with near vertical hydrate filled fractures, to constrain the CSEM inversion model. The top of salt provides improved location for brines, water saturated salt, and resistive salt. Inversions of the CSEM data map the occurrence of a ‘halo’ of conductive brines above salt. The use of the BGHSZ as a constraint on the inversion helps distinguish between free gas and gas hydrate as well as gas hydrate and water saturated sediments.

Louisiana↗
USGS2015

Recent trends in Cuba’s mining and petroleum industries

In response to recent diplomatic developments between Cuba and the United States, the National Minerals Information Center compiled available information on the mineral industries of Cuba. This fact sheet highlights a new map and table that identify mines, mineral processing facilities, and petroleum facilities as well as information on location, operational status, and ownership. It also addresses the current status of known mineral industry projects, historical developments, and trends of the Cuban economy with an emphasis on mineral industries, and the supply and demand for Cuba’s mineral resources. In 2013, Cuba was estimated to be among the world’s top ten producers of cobalt and nickel, which are the country’s leading exports. Cuba’s current crude oil and associated natural gas production from onshore and shallow water coastal reservoirs is approximately 50,000 barrels per day of liquids and about 20,000 barrels per day oil equivalent of natural gas. In 2013, the value of mining and quarrying activities accounted for 0.6 percent of Cuba’s gross domestic product (GDP), compared with 1.4 percent in 2000. The value of production from Cuba’s industrial manufacturing sector increased by 88 percent between 1993 and 2013, whereas the sector’s share in the GDP decreased by about 3 percent during the same time period reflecting economic growth in other sectors of the economy.

Fact Sheet↗
USGS1981

Preliminary composite magnetic anomaly map of part of the Northwestern United States

The magnetic anomaly data open-filed in this report represent part of a much larger data set covering most of the conterminous United States. The anomaly map consists of 10 sheets covering an area in the northwestern United States. These were prepared primarily from existing aeromagnetic data, and secondarily from ground data, the latter located primarily in North Dakota and South Dakota.

Open-File Report↗
USGS2008

Three-Dimensional Geologic Map of the Hayward Fault Zone, San Francisco Bay Region, California

A three-dimensional (3D) geologic map of the Hayward Fault zone was created by integrating the results from geologic mapping, potential field geophysics, and seismology investigations. The map volume is 100 km long, 20 km wide, and extends to a depth of 12 km below sea level. The map volume is oriented northwest and is approximately bisected by the Hayward Fault. The complex geologic structure of the region makes it difficult to trace many geologic units into the subsurface. Therefore, the map units are generalized from 1:24,000-scale geologic maps. Descriptions of geologic units and structures are offered, along with a discussion of the methods used to map them and incorporate them into the 3D geologic map. The map spatial database and associated viewing software are provided. Elements of the map, such as individual fault surfaces, are also provided in a non-proprietary format so that the user can access the map via open-source software. The sheet accompanying this manuscript shows views taken from the 3D geologic map for the user to access. The 3D geologic map is designed as a multi-purpose resource for further geologic investigations and process modeling.

Scientific Investigations Map↗