Proceedings of the U.S. Geological Survey (USGS) Sediment Workshop, February 4-7, 1997


Smith, David B.,
U.S. Geological Survey,
Denver Federal Center, MS 973,
Denver, CO 80225

The USGS Mineral Resources Program (MRP) has been collecting stream sediment samples in support of mineral resource assessments of public lands since the 1960s. Geochemical data on these sediment samples are archived in digital databases managed by MRP and the samples themselves are stored at USGS facilities in Denver, Colorado. In addition, in 1985, the Mineral Resources Program became the curator for samples and data collected during the National Uranium Resource Evaluation (NURE) Program conducted by the Department of Energy (DOE) during the middle 1970s to early 1980s. These USGS and DOE databases constitute a valuable resource for anyone who needs information on the geochemistry of stream sediments.

USGS Databases

Stream sediment geochemical data accumulated by USGS investigators are currently housed in two databases-RASS and PLUTO. RASS (an acronym for Rock Analysis Storage System) was developed in the late 1960s to provide a computerized data storage and retrieval system for geochemical data generated by the analytical laboratories of the Geologic Division. Participation in efforts to evaluate the potential for undiscovered mineral deposits on public lands meant the collection and chemical analysis of hundreds of thousands of stream sediment samples over the period of time from the late 1960s until the present day. The scale of these studies ranged from 1:24,000 for small wilderness study areas on BLM or Forest Service land to 1:500,000 or 1:1,000,000 for regional studies. The RASS database contains geochemical data for approximately 700,000 samples. The sample media are primarily stream sediments, but also include rocks, soils, heavy-mineral concentrates, waters, and plants. The RASS database became inactive in the late 1980s when all geochemical data generated by the Geologic Division laboratories were entered into the PLUTO database. PLUTO contains data for approximately 500,000 samples with stream sediments being second in quantity to rock samples.

NURE Database

The NURE program began in 1973 with a primary goal of identifying uranium resources in the United States. The Hydrogeochemistry and Stream Sediment Reconnaissance (HSSR) component of NURE was initiated in 1975. Planned systematic sampling of the entire U.S. began in 1976 under the responsibility of four regional laboratories, each with the authority to develop their own collection, analytical, and data management methods. Funding for the program ended in the early 1980s long before national coverage was achieved. The NURE sample archive was transferred from the Oak Ridge Gaseous Diffusion Plant to the USGS Mineral Resources Program in 1985. The archive is reported to contain about 380,000 original sediment samples from all four laboratories and about 250,000 replicates, splits, size fractions, or other samples. The data tapes were transferred to the USGS EROS Data Center, although, as discussed below, the data are now available on CD-ROMs produced by MRP.

Data Availability

Because of the potential importance of NURE samples and data to ongoing and future studies conducted within MRP, high priority has been placed on making the NURE data easily accessible. A CD-ROM containing data from the Western U.S. was published in 1991 (Hoffman and others, 1991). This has subsequently been superseded by two CD-ROMs containing data for the lower 48 states plus Alaska (Hoffman and Buttleman, 1994; 1996). There is currently a beta-test CD-ROM containing most of the PLUTO database that may be published in 1997. The entire PLUTO database and the RASS database are on "in-house" CD-ROMs available to scientists within MRP. Programs interested in using information from these two USGS databases should contact MRP in the early planning stages to establish staffing and funding necessary for obtaining the data and interpretations.

Use of Archival Stream Sediment Data

> The original use, and the original reason for the collection of stream sediment samples in MRP, was for geochemical exploration purposes in evaluating the mineral resource potential of Federal lands. As MRP expanded more into environmental issues during the 1980s and 90s, investigators realized that a nationally consistent geochemical database, and its representation in map form, was critical for the success of these studies. Such a database can provide baseline information on the natural abundance and spatial variation of chemical elements to which changes caused by agricultural and irrigation practices, waste disposal, urbanization, industrial pollution, mineral exploration and mining activities, and other land use practices can be compared. MRP researchers have used the databases extensively in conducting minerals-related environmental assessments of Colorado and Montana, in establishing a first-approximation of geochemical baselines for the Greater Yellowstone Ecosystem, and in determining the effects of abandoned mine lands on the geochemical landscape.

Opportunities for Enhancing and Improving the Databases

Efforts are currently underway within MRP to consolidate the data in the NURE, RASS, and PLUTO databases under one relational database management system (ORACLE). Once complete, the data will be more easily accessible and queries will be much easier than at present. In addition, there is currently a potentially important opportunity to greatly enhance and improve the database. This opportunity exists under the current international effort to establish global geochemical baselines under the auspices of the International Union of Geological Sciences Working Group on Continental Geochemical Baselines. The national-global scale effort will be carried out under the protocols developed by the International Geological Correlation Program's (IGCP) Project 259 and published in their final report entitled "A Global Geochemical Database for Environmental and Resource Management" (Darnley and others, 1995).

IGCP Project 259, International Geochemical Mapping, terminated in 1994 and was succeeded by Project 360, Global Geochemical Baselines, where internationally agreed upon protocols and procedures for geochemical baseline mapping continue to be developed. The initial phase of determining global geochemical baselines will be to establish a geochemical reference network through the collection of a variety of materials (drainage basin sediments, regolith, surface humus, surface water) from approximately 5,000 cells, each 160 x 160 km, over the entire surface of the earth. About 365 of these cells contain at least bits of U.S. lands. Through the cooperation of the USGS, State geological surveys, and other interested agencies such as the Department of Agriculture and the Environmental Protection Agency, the establishment of a consistent and comprehensive geochemical database based on stream sediments as a primary sample medium, is a very reachable goal.


Darnley, A.G., Bjorklund, A., Bolviken, B., Gustavsson, N., Koval, P.V., Plant, J.A., Steenfelt, A. , Tauchid, M., and Xie Xuejing, 1995, A Global Geochemical Database for Environmental and Resource Management; Recommendations for International Geochemical Mapping , Final Report of IGCP 259: UNESCO Publishing, 122p.

Hoffman, J.D., Gunells, G.B., and McNeal, J.M, 1991, National Geochemical Data Base: National Uranium Resource Evaluation Data for the Conterminous Western United States: U.S. Geological Survey Digital Data Series DDS-1.

Hoffman, J.D., and Buttleman, Kim, 1994, National Geochemical Data Base: National Uranium Resource Evaluation Data for the Conterminous United States: U.S. Geological Survey Digital Data Series DDS- 18-A.

Hoffman, J.D., and Buttleman, Kim, 1996, National Geochemical Data Base: 1. National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) data for Alaska, formatted for GSSEARCH data base search software, 2. NURE HSSR data formatted as dBASE files for Alaska and the conterminous United States, 3. NURE HSSR data as originally compiled by the Department of Energy for Alaska and the conterminous United States: U. S. Geological Survey Digital Data Series DDS-18-B.


Smith, David B., U.S. Geological Survey, Lakewood, CO: Currently serves as a specialist in exploration and regional geochemistry with the Mineral Resources Program (MRP). Previous experience during 21 years with the USGS includes research in geochemical exploration techniques using, predominantly, stream sediments and heavy-mineral concentrates derived from stream sediments as sample media in the western U.S. and western China. Current activities include coordinating the geochemical database project in MRP; research on establishing geochemical baselines in areas of past, current, or future mining activities; completing a soil geochemical map for the conterminous U.S.; and acting as liaison to the International Union of Geological Sciences Working Group on Continental Geochemical Baselines.
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