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USGS1999

Geologic datasets for weights of evidence analysis in northeast Washington: 3. Minerals-related permits on national forests, 1967 to 1998

Permits to explore for and (or) develop mineral resources on forest land can be used to indicate locations and types of mineral-related activities on national forests. Permits for these activities require filing at the Forest Service a Notice of Intention (Notice) to conduct mineral exploration activities and (or) a Plan of Operation (Plan). A Plan of Operation is required is significant activities are anticipated. This compilation of Notices and Plans for the Colville, Kaniksu, Okanogan, and Wenatchee National Forests between 1967 and 1998 is intended for use in combination with geologic and economic information to predict future mineral-related activities in the region.

Washington↗

USGS1999

Geologic datasets for weights-of-evidence analysis in northeast Washington: 3. Minerals-related permits on national forests, 1967-1998

Washington↗

USGS2010

Geologic Map of the House Rock Valley Area, Coconino County, Northern Arizona

This geologic map is a cooperative effort of the U.S. Geological Survey (USGS), the Bureau of Land Management, the National Park Service, and the U.S. Forest Service to provide a geologic database for resource management officials and visitor information services. This map was produced in response to information needs related to a proposed withdrawal of three segregated land areas near Grand Canyon National Park, Arizona, from new hard rock mining activity. House Rock Valley was designated as the east parcel of the segregated lands near the Grand Canyon. This map was needed to provide connectivity for the geologic framework of the Grand Canyon segregated land areas. This geologic map of the House Rock Valley area encompasses approximately 280 mi2 (85.4 km2) within Coconino County, northern Arizona, and is bounded by longitude 111 degrees 37'30' to 112 degrees 05' W. and latitude 36 degrees 30' to 36 degrees 50' N. The map area is in the eastern part of the Arizona Strip, which lies within the southern Colorado Plateaus geologic province (herein Colorado Plateau). The Arizona Strip is the part of Arizona lying north of the Colorado River. The map is bound on the east by the Colorado River in Marble Canyon within Grand Canyon National Park and Glen Canyon National Recreation Area, on the south and west by the Kaibab National Forest and Grand Canyon National Game Preserve, and on the north by the Vermilion Cliffs Natural Area, the Paria Canyon Vermilion Cliffs Wilderness Area, and the Vermilion Cliffs National Monument. House Rock State Buffalo Ranch also bounds the southern edge of the map area. The Bureau of Land Management Arizona Field Office in St. George, Utah, manages public lands of the Vermilion Cliffs Natural Area, Paria Canyon - Vermilion Cliffs Wilderness and Vermilion Cliffs National Monument. The North Kaibab Ranger District in Fredonia, Arizona, manages U.S. Forest Service land along the west edge of the map area and House Rock State Buffalo Ranch. Other lands include about 13 sections of Arizona State land, about ? of a section of private land along House Rock Wash, and about 1? sections of private land at Cliff Dwellers Lodge, Vermilion Cliffs Lodge, and Marble Canyon, Arizona. Landmark features within the map area include the Vermilion Cliffs, Paria Plateau, Marble Canyon, and House Rock Valley. Surface drainage in House Rock Valley is to the east toward the Colorado River in Marble Canyon. Large tributaries of Marble Canyon from north to south include Badger Canyon, Soap Creek, Rider Canyon, North Canyon, Bedrock Canyon, and South Canyon. Elevations range from about 2,875 ft (876 m) at the Colorado River in the southeast corner of the map to approximately 7,355 ft (2,224 m) on the east rim of Paria Plateau along the north-central edge of the map area. Three small settlements are in the map area along U.S. Highway 89A, Cliff Dwellers Lodge, Vermilion Cliffs Lodge, and Marble Canyon, Arizona. The community of Jacob Lake is about 9 mi (14.5 km) west of House Rock Valley on the Kaibab Plateau. Lees Ferry is 5 mi (8 km) north of Marble Canyon and marks the confluence of the Paria and Colorado Rivers and the beginning of Marble Canyon. U.S. Highway 89A provides access to the northern part of the map area. Dirt roads lead south into House Rock Valley from U.S. Highway 89A and are collectively maintained by the Bureau of Land Management, the U.S. National Forest Service, and the Grand Canyon Trust. House Rock Valley is one of the few remaining areas where uniform geologic mapping is needed for connectivity to the regional Grand Canyon geologic framework. This information is useful to Federal and State resource managers who direct environmental and land management programs that encompass such issues as range management, biological studies, flood control, water, and mineral-resource investigations. The geologic information will support future and ongoing geologic investigations and scientific studies

Scientific Investigations Map↗

USGS2007

Introduction

The inevitable increase in demand and continuing depletion of accessible oil and gas resources during the 21st century will cause greater dependence on energy minerals such as coal, uranium, and unconventional sources of oil and natural gas to satisfy our increasing energy needs. The Energy Minerals Division (EMD) of the American Association of Petroleum Geologists (AAPG) is a membership-based technical interest group with goals to: (1) advance the science of geology, especially as it relates to exploration, discovery, and production of mineral resources and subsurface gas and liquids (other than conventional oil and gas) for energy-related purposes; (2) foster the spirit of scientific research; (3) disseminate information related to the geology of energy minerals and the associated technology of energy mineral resources extraction; and (4) advance the professional wellbeing of its members. This article contains a brief summary of some of the 2006 annual committee reports presented to the EMD Leadership. These reports are available to the EMD Membership at http://emd.aapg.org/members_only. This collection of short reports is presented here by the EMD as a service to the general geologic community and to simulate interest in the focus technical areas of EMD.

Natural Resources Research↗

USGS1986

Quantitative estimation of undiscovered mineral resources: A case study of US Forest Service Wilderness tracts in the Pacific Mountain system

The need by land managers and planners for more quantitative measures of mineral values has prompted scientists at the U.S. Geological Survey to test a probabilistic method of mineral resource assessment on a portion of the wilderness lands that have been studied by the Survey during the past 20 years. A quantitative estimate of undiscovered mineral resources is made by linking the techniques of subjective estimation, geologic mineral deposit models, and Monte Carlo simulation. The study, which uses grade-tonnage and occurrence models for 21 geologic deposit types, considers 91 U.S. Forest Service wilderness tracts in California, Nevada, Oregon, and Washington. Estimates of the amounts of the 11 metals contained in undiscovered mineral deposits of the types studied range from negligible to several years of U.S. consumption. Although these estimates are limited to metals contained in undiscovered deposits of a small number of metallic mineral deposit types, the assessment procedure can be expanded by the use of additional deposit models and by using information about identified mineral resources. This will allow models of economic processes such as exploration, development, and production to be applied.

Economic Geology↗

USGS2002

Preliminary cellular-automata forecast of permit activity from 1998 to 2010, Idaho and Western Montana

For public land management in Idaho and western Montana, the U.S. Forest Service (USFS) has requested that the U.S. Geological Survey (USGS) predict where mineral-related activity will occur in the next decade. Cellular automata provide an approach to simulation of this human activity. Cellular automata (CA) are defined by an array of cells , which evolve by a simple transition rule, the automaton . Based on exploration trends, we assume that future exploration will focus in areas of past exploration. Spatial-temporal information about mineral-related activity, that is permits issued by USFS and Bureau of Land Management (BLM) in the last decade, and spatial information about undiscovered resources, provide a basis to calibrate a CA. The CA implemented is a modified annealed voting rule that simulates mineral-related activity with spatial and temporal resolution of 1 mi 2 and 1 year based on activity from 1989 to 1998. For this CA, the state of the economy and exploration technology is assumed constant for the next decade. The calibrated CA reproduces the 1989–1998-permit activity with an agreement of 94%, which increases to 98% within one year. Analysis of the confusion matrix and kappa correlation statistics indicates that the CA underestimates high activity and overestimates low activity. Spatially, the major differences between the actual and calculated activity are that the calculated activity occurs in a slightly larger number of small patches and is slightly more uneven than the actual activity. Using the calibrated CA in a Monte Carlo simulation projecting from 1998 to 2010, an estimate of the probability of mineral activity shows high levels of activity in Boise, Caribou, Elmore, Lincoln, and western Valley counties in Idaho and Beaverhead, Madison, and Stillwater counties in Montana, and generally low activity elsewhere.

Idaho, Montana↗

USGS2002

What are parasitologists doing in the United States Geological Survey?

The United States Geological Survey (USGS) was formed in 1879 as the nation's primary natural science and information agency. The mission of the agency is to provide scientific information to a??describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.a?? Prior to 1996, the USGS comprised 3 divisions or disciplines: geology, mapping, and water. Historically, the agency was most noted for cartographic products that were used widely by both government and private sector. With the inclusion of the National Biological Service into the USGS in 1996 as the Biological Resource Discipline (BRD), a living resources dimension was added to the earth sciences character of the USGS. With the addition of BRD, the bureau is able now to contribute both the physical and biological sciences to address the nation's resource management problems.

Comparative Parasitology↗

USGS1975

A brief history of the U.S. Geological Survey

Established by an Act of Congress in 1879 and charged with responsibility for "classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain," the U. S. Department of the Interior's Geological Survey has been the Nation's principal source of information about its physical resources the configuration and character of the land surface, the composition and structure of the underlying rocks, and the quality, extent, and distribution of water and mineral resources. Although primarily a research and fact-finding agency, it has responsibility also for the classification of Federal mineral lands and waterpower sites, and since 1926 it has been responsible for the supervision of oil and mining operations authorized under leases on Federal land. From the outset, the Survey has been concerned with critical land and resource problems. Often referred to as the Mother of Bureaus, many of its activities led to the formation of new organizations where a management or developmental function evolved. These included the Reclamation Service (1902), the Bureau of Mines (1910), the Federal Power Commission (1920), and the Grazing Service (1934, since combined with other functions as the Bureau of Land Management). Mrs. Rabbitt's summary of the Survey's history in the following pages brings out well the development of these diverse activities and the Survey's past contributions to national needs related to land and resources.

General Information Product↗

USGS1999

Map showing the potential for mineral deposits associated with Precambrian mafic and ultramafic rocks in the Blacktail and Henrys Lake Mountains and the Greenhorn and Ruby Ranges of southwestern Montana

In response to requests from the Bureau of Land Management (BLM) and the U.S. Forest Service (USFS), the U.S. Geological Survey (USGS) conducted a mineral resource assessment in the Dillon BLM Resource Area in Beaverhead and Madison Counties, southwestern Montana. These agencies use mineral resource data in creating and updating land-use management plans for federal lands for the reasonably foreseeable future. Mineral resources that have not been developed in the past may be developed in the future, based on changing commodity demands and market conditions. Therefore, federal land managers need geologic information on known mineral occurrences as well as on areas that are permissive for the occurrence of undiscovered mineral resources. This map was prepared to provide this type of geologic information for mineral deposits that can be associated with ultramafic rocks. Areas of exposed Precambrian ultramafic rocks are labeled with uppercase letters (A-F). Sources of geologic maps used to compile this map are shown on the smaller index map ("Index to Geologic Mapping"); lowercase letters (a-m) on the index map are keyed to the reference list.

Montana↗

USGS2009

Rock slope stability analysis along the North Carolina section of the Blue Ridge Parkway: Using a geographic information system (GIS) to integrate site data and digital geologic maps

In 2008, the North Carolina Geological Survey (NCGS) completed a five-year geologic and geohazards inventory of the 406-km long North Carolina segment of the Blue Ridge Parkway (BRP). The ArcGIS™ format deliverables for rock slopes include a slope movement and slope movement deposit database and maps and site-specific rock slope stability assessments at 158 locations. Database entries for known and potential rock slope failures include: location data, failure modes and dimensions, activity dates and levels, structural and lithologic data, the occurrence of sulfide minerals and acid-producing potential test results. Rock slope stability assessments include photographs of the rock cuts and show locations and orientations of rock data, seepage zones, and kinematic stability analyses. Assigned preliminary geologic hazard ratings of low, moderate and high indicate the generalized relative probability of rock fall and/or rock slide activity at a given location. Statistics compiled based on the database indicate some general patterns within the data. This information provides the National Park Service with tools that can aid in emergency preparedness, and in budgeting mitigation, maintenance and repair measures.

Conference Paper↗

USGS1987

Geochemical survey maps of the wildernesses and roadless areas in the White Mountains National Forest, Coos, Grafton, and Carroll counties, New Hampshire

The Wilderness Act (Public Law 88-577, September 3, 1964) and related acts require the U.S. Geological Survey and the U.S. Bureau of Mines to survey certain areas on Federal lands to determine what mineral values, if any, may be present. Results must be made available to the public and be submitted to the President and the Congress. This report presents the results a geochemical survey of the Great Gulf and Presidential Range-Dry River Wilderness Areas; the Dartmouth Range, Wild River, Pemigewasset, Kinsman Mountain, Mount Wolf-Gordon Pond, Jobildunk, Carr Mountain, Sandwich Range, and the Dry River Extention (2 parcels) Roadless Areas; and the intervening and immediately surrounding areas in the White Mountain National Forest, Coos, Grafton, and Carroll Counties, New Hampshire. The Great Gulf Wilderness was established when the Wilderness Act was passed in 1964, and the Presidential Range-Dray Wiver Wilderness was established by Public Law 93-622, January 3, 1975. The Dartmouth Range, Wild River, Pemigewasset, Kinsman Mountain, Mount Wolf-Gordon Pond, Carr Mountain, and Jobildunk areas were classified as a further planning area during the Second Roadless Area Review and Evaluation (RARE II) by the U.S. Forest Service, January 1979. The White Mountain National Forest contains two established wilderness areas and ten additional RARE II roadless areas, covering a total of about 380 square miles. The location of these areas is shown on figure 1 and further information about them is contained in table 2. In order to treat all these separate areas as a single entity, they, along with the immediately surrounding areas, were combined into one study area, hereafter referred to as the study area, of about 1,300 square miles. This map is based on joint investigations by the U.S. Geological Survey and the Office of the State Geologists of New Hampshire. The geochemical survey was conducted in the summer of 1980 and was integrated with an on-going multidisciplinary study of mineral resources of the Sherbrooke and Lewiston 1°x2° quadrangles under the Conterminous United States Mineral Assessment Program (CUSMAP).

New Hampshire↗

USGS2000

Northeastern Gulf of Mexico Coastal and Marine Ecosystem Program: Coastal Characterization: an overview and update

The U.S. Geological Surveys Biological Resources Division (BRD) mission is to provide leadership in gathering, analyzing, and disseminating biological information as support for sound management of the Nation's natural resources. Since becoming operational in October of 1996 through the transfer of programs from various bureaus within the Department of the Interior, the BRD, in cooperation with other Federal, State, and local partners, has begun research, inventory and monitoring, information sharing, and technology transfer. Through these activities, the BRD is fostering an understanding of biological systems and their benefits to society, and providing the essential scientific support and technical assistance required for management and policy decisions. The role of BRD' s National Wetlands Research Center (NWRC) in Lafayette, Louisiana, with project offices in Baton Rouge, LA and Gulf Breeze, FL, is to provide leadership in research and development related to the Nation's natural resources for the Southeast. The research focuses on wetlands ecology, animal ecology, and the development and application of spatial analysis techniques for natural resource related studies. Current geographic information system (GIS) technologies in use at NWRC are designed to provide natural resource managers with the on-line data and computerized techniques necessary to make informed decisions. Major GIS activities at NWRC include: compilation and analysis of digital databases for monitoring of natural resources; integration and transfer of databases with existing digital databases from various sources into a comprehensive GIS; and development of multifunctional decision support systems for natural resource managers using these data. NWRC is also an active participant in the National Information Infrastructure (NIT), in particular the National Spatial Data Infrastructure (NSDI) and the National Biological Information Infrastructure (NBTI), which will facilitate the dissemination of research results and other knowledge and information gained from these efforts. This summary and the three summaries that follow provides an overview and update of a four year study entitled, Northeastern Gulf of Mexico Coastal and Marine Ecosystem Program: Coastal Characterization.

Minerals Management Service↗

USGS1976

United States Geological Survey Annual Report, Fiscal Year 1975

The Survey resumes the practice of annually summarizing the progress it has made in identifying the Nation's land, water, energy, and mineral resources, classifying federally owned mineral lands and waterpower sites, and in supervising the exploration and development of energy and mineral resources on Federal and Indian lands. The Annual Report for 1975 consists of five parts: * The Year in Review - a review of the issues and events which affected Survey programs and highlights of program accomplishments. * Perspectives - several short papers which address major resource issues and summarize recent advances in the earth sciences. * A description of the Survey's budget, programs, and accomplishments. * A set of statistical tables and related information which documents program trends, workloads, and accomplishments. * A compendium of Survey publications and information services available to the public. One purpose of this report is to increase public awareness and understanding of the Geological Survey's programs and, more generally, of the role of earth sciences information in helping to resolve many of the natural resource conflicts that face our society now and in the years ahead. To be useful, however, information must be available and readily accessible to those responsible for natural resource policy at the time that the decisions are made. This report emphasizes the types of information products and services provided by the Survey and tells how to obtain additional information.

Annual Report↗

USGS2004

Chapter G: Tentative Correlation Between CIPW Normin pl (Total Plagioclase) and Los Angeles Wear in Precambrian Midcontinental Granites-Examples from Missouri and Oklahoma, with Applications and Limitations for Use

The normative chemical classification of Cross, Iddings, Pirsson, and Washington (CIPW) is commonly used in igneous petrology to distinguish igneous rocks by comparing their magmatic chemistries for similar and dissimilar components. A potential use for this classification other than in petrologic studies is in the rapid assessment of aggregate sources, possibly leading to an economic advantage for an aggregate producer or user, by providing the opportunity to determine whether further physical testing of an aggregate is warranted before its use in asphalt or concrete pavement. However, the CIPW classification currently should not be substituted for the physical testing required in specifications by State departments of transportation. Demands for physical testing of aggregates have increased nationally as users seek to maximize the quality of the aggregate they purchase for their pavements. Concrete pavements are being laid with increased thicknesses to withstand increasing highway loads. New pavement mixes, most notably Superior Performance Asphalt Pavement ('Superpave'), are designed for additional service life. For both concrete and asphalt, the intent is to generate a durable pavement with a longer service life that should decrease overall life-cycle costs. Numerous aggregate producers possess chemical-composition data available for examination to answer questions from the potential user. State geological surveys also possess chemical-composition data for stone sources. Paired with the results of physical testing, chemical- composition data provide indicative information about stone durability and aggregate strength. The Missouri Department of Transportation has noted a possible relation among coarse-grained Precambrian granites of the midcontinental region, correlating the results of abrasion testing with the contents of normative minerals, also known as normins, calculated from chemical composition data. Thus, normin pl ( total plagioclase) can predict, by way of simple regression, the Los Angeles wear for granite samples collected in Missouri. The results of this abrasion testing were extended to another granite in Oklahoma where normin pl predicted Los Angeles wear to within 0.6 percent. This relation may also exist for granitic rocks outside the Oklahoma-Missouri region, as well as for other igneous-rock types.

Bulletin↗

USGS1991

Water-resources investigations in Pennsylvania; programs and activities of the U.S. Geological Survey, 1990-91

The U.S. Geological Survey (USGS) was established by an act of Congress on March 3, 1879, to provide a permanent Federal agency to conduct the systematic and scientific 'classification of the public lands, and examination of the geological structure, mineral resources, and products of national domain'. Since 1879, the research and fact-finding role of the USGS has grown and has been modified to meet the changing needs of the Nation it serves. Moneys for program operation of the USGS in Pennsylvania come from joint-funding agreements with State and local agencies , transfer of funds from other Federal agencies, and direct Federal allotments to the USGS. Funding is distributed among the following programs: National Water Quality Assessment; water quality programs; surface water programs; groundwater programs; logging and geophysical services; computer services; scientific publication and information; hydrologic investigations; and hydrologic surveillance. (Lantz-PTT)

Open-File Report↗

USGS2007

Earth science and public health: Proceedings of the Second National Conference on USGS Health-Related Research

The mission of the U.S. Geological Survey (USGS) is to serve the Nation by providing reliable scientific information to describe and understand the earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life. As the Nation?s largest water, earth, and biological science and civilian mapping agency, the USGS can play a significant role in providing scientific knowledge and information that will improve our understanding of the relations of environment and wildlife to human health and disease. USGS human health-related research is unique in the Federal government because it brings together a broad spectrum of natural science expertise and information, including extensive data collection and monitoring on varied landscapes and ecosystems across the Nation. USGS can provide a great service to the public health community by synthesizing the scientific information and knowledge on our natural and living resources that influence human health, and by bringing this science to the public health community in a manner that is most useful. Partnerships with health scientists and managers are essential to the success of these efforts. USGS scientists already are working closely with the public health community to pursue rigorous inquiries into the connections between natural science and public health. Partnering agencies include the Armed Forces Institute of Pathology, Agency for Toxic Substances Disease Registry, Centers for Disease Control and Prevention, U.S. Environmental Protection Agency, Food and Drug Administration, Mine Safety and Health Administration, National Cancer Institute, National Institute of Allergy and Infectious Disease, National Institute of Environmental Health Sciences, National Institute for Occupational Safety and Health, U.S. Public Health Service, and the U.S. Army Medical Research Institute of Infectious Diseases. Collaborations between public health scientists and earth scientists can lead to improved solutions for existing and emerging environmental health problems. This report summarizes the presentations and discussions held at the Second National Conference on USGS Health-Related Research, held at the USGS national headquarters in Reston, Virginia. The report presents 68 abstracts of technical presentations made at the conference and summaries of six topical breakout sessions. The abstracts cover a broad range of issues and demonstrate connections between human health and the quality and condition of our environment and wildlife. The summaries of the topical breakout sessions present ideas for advancing interdisciplinary science in areas of earth science and human health.

Scientific Investigations Report↗

USGS2011

Development of soil properties and nitrogen cycling in created wetlands

Mitigation wetlands are expected to compensate for the loss of structure and function of natural wetlands within 5–10 years of creation; however, the age-based trajectory of development in wetlands is unclear. This study investigates the development of coupled structural (soil properties) and functional (nitrogen cycling) attributes of created non-tidal freshwater wetlands of varying ages and natural reference wetlands to determine if created wetlands attain the water quality ecosystem service of nitrogen (N) cycling over time. Soil condition component and its constituents, gravimetric soil moisture, total organic carbon, and total N, generally increased and bulk density decreased with age of the created wetland. Nitrogen flux rates demonstrated age-related patterns, with younger created wetlands having lower rates of ammonification, nitrification, nitrogen mineralization, and denitrification potential than older created wetlands and natural reference wetlands. Results show a clear age-related trajectory in coupled soil condition and N cycle development, which is essential for water quality improvement. These findings can be used to enhance N processing in created wetlands and inform the regulatory evaluation of mitigation wetlands by identifying structural indicators of N processing performance.

Wetlands↗

USGS1999

Stratigraphic framework and heavy minerals of the continental shelf of Onslow and Long Bays, North Carolina

One hundred fourteen vibracores from the Atlantic continental shelf offshore of southeastern North Carolina were opened, described, and processed over several contract years (years 6-9) of the Minerals Management Service-Association of American State Geologists Continental Margins program. Reports for years 9 and 10 of the program compiled the results of the work and assembled the data for release as an interactive CD-ROM report, respectively. The continental shelf of Onslow and Long Bays consists predominantly of outcropping Cretaceous through late Tertiary geologic units. Nearshore these units are covered and incised by late Tertiary and Quaternary units. From oldest to youngest, formally recognized geologic units mapped as part of this study are the Late Cretaceous Peedee Formation-a muddy, fine- to medium-grained quartz sand with trace amounts of glauconite and phosphate; the Paleocene Beaufort Formation-a muddy, fine- to medium-grained glauconitic quartz sand with locally occurring turritelid-mold biosparrudite; the middle Eocene Castle Hayne Formation-a sandy bryozoan biomicrudite and biosparrudite; the Oligocene River Bend Formation-a sandy molluscan-mold biosparrudite; and the Miocene Pungo River Formation-a medium-grained, poorly sorted slightly shelly phosphatic sand. Informal units include a very widespread, unnamed fine- to very fine grained, well-sorted, dolomitic muddy quartz sand that is biostratigraphically equivalent to the Oligocene River Bend Formation; several large valley-fill lithosomes composed of biomicrudite, biomicrite, and biosparrudite of Plio/Pleistocene age; muddy, shelly sands and silty clays of Pliocene, Pleistocene, or mixed Plio/Pleistocene age; and loose, slightly shelly, medium- to coarse-grained sands assigned a Holocene age. Heavy minerals (SG > 2.96) comprise an average of 0.54 wt% (on a bulk-sample basis) of the sediments in 306 samples derived from the 114 vibracores. Heavy-mineral content ranges from <0.01 to 3.69 wt%. The economic heavy mineral content (EHM = ilmenite + zircon + rutile + aluminosilicates + leucoxene [altered ilmenite] + monazite) of the bulk samples averages 0.26 wt% in a range of <0.01-1.70 wt%. As a percentage of the heavy-mineral concentrate, the average EHM value is 45.78% in a range of 0.27-68.60%. The distribution of heavy minerals offshore of southeastern North Carolina is controlled by the lithostratigraphic framework. The unnamed Oligocene sand unit has the highest heavy-mineral content, averaging 0.86 wt% on a bulk-sample basis. The remaining geologic units and their heavy-mineral content (in decreasing order of abundance) are Beaufort (0.64%), Holocene sand (0.60%), Plio-Pleistocene muddy sand and silty clay (0.59%), Peedee (0.42%), River Bend (0.34%), Plio-Pleistocene carbonate (0.12%), and Castle Hayne (0.08%). The heavy-mineral assemblage is fairly consistent throughout the different units. Significantly smaller percentages of heavy minerals correlate with increased amounts of CaCO 3 in the sediments. The sediments analyzed in this study have significantly lower overall heavy-mineral content, as well as lower EHM content than sediments that are known to host commercially important heavy-mineral deposits in the southeastern United States. The potential for economic deposits of heavy minerals in the area of this study, therefore, appears to be limited.

Marine Georesources and Geotechnology↗