Publications

The Chesapeake Bay impact structure, formed by a comet or meteorite that struck the Virginia continental shelf about 35.5 million years ago, is the focus of an extensive coring project by the U.S. Geological Survey and its cooperators. Organic-walled dinocysts recovered from impact-generated deposits in a deep core inside the 85-90 km-wide crater include welded organic clumps and fused...

Diffuse reflectance spectra of 15 mineral species commonly associated with sulphide-bearing mine wastes show diagnostic absorption bands related to electronic processes involving ferric and/or ferrous iron, and to vibrational processes involving water and hydroxyl. Many of these absorption bands are relatively broad and overlapping; however, spectral analysis methods, including continuum...

Inferred reserves are expected additions to proved reserves of oil and gas fields discovered as of a certain date. Inferred reserves accounted for 65 percent of the total oil and 34 percent of the total gas assessed in the U.S. Geological Survey's 1995 National Assessment of oil and gas in onshore and State offshore areas. The assessment predicted that over the 80-year period from 1992...

Epsomite (MgSO4·7H2O) and hexahydrite (MgSO4·6H2O) are common minerals found in marine evaporite deposits, in saline lakes as precipitates, in weathering zones of coal and metallic deposits, in some soils and their efflorescences, and possibly on the surface of Europa as evaporite deposits. Thermodynamic properties of these two minerals reported in the literature are in poor agreement...

The digital magnetic anomaly database and map for the North American continent is the result of a joint effort by the Geological Survey of Canada (GSC), U. S. Geological Survey (USGS), and Consejo de Recursos Minerales of Mexico (CRM). This integrated, readily accessible, modern digital database of magnetic anomaly data is a powerful tool for further evaluation of the structure, geologic...

The United States uses large quantities of natural aggregate to build and maintain a continuously expanding infrastructure. In recent years, per capita demand for aggregate in the United States has grown to about 9.7 metric tons (10.7 tons) per person per year. Over the next 25 years, the aggregate industry expects to mine quantities equivalent to all aggregate mined in the United States...

This publication includes maps, grids, and flightline databases of a detailed aerial survey and maps and grids of satellite data in Berrien County, Michigan. The purpose of the survey was to map aquifers in glacial terrains. This was accomplished by using a DIGHEMVRES mufti-coil, mufti-frequency electromagnetic system supplemented by a high sensitivity cesium magnetometer and 256-channel

No abstract available.

Bedrock, forest floor, and mineral soil sampling in Voyageurs National Park (VNP), Minnesota in 2000 and 2001 is part of a multidisciplinary project that includes the U. S. Geological Survey, National Park Service, University of Wisconsin – La Crosse, Minnesota Pollution Control Agency, and the Minnesota Department of Natural Resources. The joint project is examining the distribution of...

Since the beginning of economic geology as a subdiscipline of the geological sciences, economic geologists have tended to classify mineral deposits on the basis of geological, mineralogical, and geochemical criteria, in efforts to systematize our understanding of mineral deposits as an aid to exploration. These efforts have led to classifications based on commodity, geologic setting (Cox...

No abstract available.

During middle Miocene time, western North America was subject to flood-basalt volcanism, dike-swarm injection, and broad-scale fracturing and folding of the crust. We propose a simple model to account for these events and for a regional pattern of geologic and geophysical features. Aeromagnetic maps reveal some of the most important elements of this pattern, which are several narrow...